JP7829821B2 - System stabilization system and system stabilization method - Google Patents

Description

This disclosure relates to a grid stabilization system and a grid stabilization method.

Various technologies have been proposed for controlling power systems. For example, Patent Document 1 proposes a technology for calculating the reactive power that a power source should output in the event of a fault in a power system.

Japanese Patent Publication No. 2022-21919

When an accident occurs in a power system, a protective relay system is used to eliminate the accident to prevent its effects from spreading over a wide area. However, when transmission lines and transformers are opened as a result, the voltage and power flow conditions in the power system can change rapidly, potentially causing overload and abnormal voltage in the transmission lines. Therefore, to resolve such overload and abnormal voltage, power supply restriction or load restriction is performed by disconnecting generators or loads from the power system using a system stabilization system or similar means.

However, as power systems become more complex, conventional technology has the problem of not being able to properly determine which generators and loads should be interrupted and by what amount.

Therefore, this disclosure has been made in view of the above-mentioned problems, and aims to provide a technology that can appropriately determine the generator and load to be controlled, and the amount to be controlled.

The first grid stabilization system according to this disclosure includes: an acquisition unit that acquires measurement information of a power system including a generator and a load; an accident occurrence determination unit that determines whether or not an accident has occurred in the power system based on the measurement information; a model generation unit that generates a grid model based on the measurement information and the equipment information of the power system when it is determined that an accident has occurred; and a control content calculation unit that, when it is determined that an overload or abnormal voltage has occurred based on the grid model, calculates control content including a control target and a control amount of the control target by optimal power flow calculation with the control amount of the control target as a variable, based on the grid model and the equipment information, wherein the control content includes a break-off amount which is the control amount of at least one of the generator and the load that are the control targets; and further includes a sensitivity calculation unit that calculates the sensitivity of at least one of the power flow of the power transmission lines of the power system and the voltage of the busbars of the power system based on the control content .

The second grid stabilization system according to this disclosure comprises a central computing unit and a slave station unit capable of communicating with the central computing unit, wherein the central computing unit includes a first acquisition unit that acquires measurement information of a power system including generators and loads, a model generation unit that generates a grid model for each of the predetermined fault patterns based on the measurement information, equipment information of the power system, and a predetermined number of fault patterns, and when it is determined that an overload or abnormal voltage occurs based on the grid model of the fault pattern, it calculates control content including a controlled object and a controlled amount of the controlled object based on the grid model and equipment information by optimal power flow calculation with the controlled amount of the controlled object as a variable, and matches the fault pattern with the control content. The system includes a control content calculation unit that generates an attached control table, the control content including an interruption amount which is the control quantity of at least one of the generator and the load that are the control targets, the slave station device includes a second acquisition unit that acquires the measurement information and the control table, an accident occurrence determination unit that determines whether or not the accident pattern of the control table has occurred in the power system based on the measurement information, and a control content determination unit that determines the control content associated with the accident pattern determined to have occurred in the control table , and the central processing unit further includes a sensitivity calculation unit that calculates the sensitivity of at least one of the power flow of the power transmission lines of the power system and the voltage of the busbars of the power system based on the control content .

According to this disclosure, based on a system model and equipment information, the control content, including the controlled object and the controlled quantity of the controlled object, is calculated by optimal power flow calculation. The control content includes a break-off quantity, which is at least one of the controlled quantities of the generator and load that are the controlled objects. With such a configuration, the generator and load to be controlled and their controlled quantities can be appropriately determined.

The purpose, features, aspects, and advantages of this disclosure will become more apparent from the following detailed description and accompanying drawings.

This is a schematic diagram showing a power grid using the grid stabilization system according to Embodiment 1. This is a block diagram showing the configuration of the system stabilization system according to Embodiment 1. This figure shows the concept of the system model according to Embodiment 1. This is a flowchart showing the operation of the system stabilization system according to Embodiment 1. This is a block diagram showing the configuration of the system stabilization system according to Embodiment 2. This figure shows the model used in the sensitivity calculation unit according to Embodiment 2. This is a block diagram showing the configuration of the system stabilization system according to Embodiment 3. A flowchart showing the operation of the system stabilization system according to Embodiment 3. This is a schematic diagram showing a power grid using the grid stabilization system according to Embodiment 4. This is a block diagram showing the configuration of the central computing unit of the system stabilization system according to Embodiment 4. This is a block diagram showing the configuration of the slave station device of the grid stabilization system according to Embodiment 4. This is a flowchart showing the operation of the central computing unit of the system stabilization system according to Embodiment 4. This is a flowchart showing the operation of the slave station device of the system stabilization system according to Embodiment 4. This block diagram shows the hardware configuration of a system stabilization system relating to other variations. This block diagram shows the hardware configuration of a system stabilization system relating to other variations.

<Embodiment 1>
Figure 1 is a schematic diagram showing a power system using the grid stabilization system 8 according to this first embodiment. The power system in Figure 1 comprises a power transmission and distribution system 1, a generator 2, a load 3, a renewable energy source (hereinafter referred to as "renewable energy source") 4, a storage battery 5, a voltage control device 6, a measuring device 7, and a grid stabilization system 8.

The power transmission and distribution system 1 connects the generator 2, load 3, renewable energy source 4, storage battery 5, and voltage control equipment 6 so that power is transferred between them. The power transmission and distribution system includes, for example, transmission lines and busbars.

The generator 2 includes at least one of the following types of generators: a nuclear power generator, a thermal power generator, a hydroelectric power generator, etc. In this specification, for example, at least one of A, B, C, ..., and Z means any one of all combinations obtained by selecting one or more types from the groups A, B, C, ..., and Z.

Load 3 includes, for example, equipment of a consumer that uses power from the power grid. Renewable energy source 4 includes, for example, equipment with inverters such as solar power generators and wind power generators. Storage battery 5 includes, for example, a secondary battery system composed of lithium-ion batteries, NAS batteries, etc., or at least one of a flywheel battery and an electric double-layer capacitor. Voltage control equipment 6 is voltage control equipment other than renewable energy source 4 and storage battery 5, and includes, for example, phase adjustment equipment and FACTS (Flexile AC Transmission System) equipment such as SVC (Reactive Power Compensator) and STATCOM (Self-Commutated Reactive Power Compensator).

The measuring device 7 generates measurement information for the power system, including the generator 2, load 3, renewable energy source 4, storage battery 5, and voltage control equipment 6. The measurement information includes, for example, the voltage, current, power, frequency, and switching status of protective relays for each part of the power transmission and distribution system 1.

A protective relay (not shown) is installed, for example, in the transmission lines, busbars, generators 2, loads 3, and renewable energy sources 4 in the power transmission and distribution system 1. It detects overvoltage, overcurrent, etc., caused by an accident and electrically shuts off the power equipment at the location of the accident to prevent the accident from spreading to a wider area, thereby clearing the accident.

A power cutoff device or load cutoff device (not shown) is installed, for example, between the power transmission and distribution system 1 and the generator 2, load 3, and renewable energy source 4, and cuts off the connection between the power transmission and distribution system 1 and the generator 2, load 3, and renewable energy source 4 by a commanded amount. In the following description, unless otherwise distinguished, the generator 2, load 3, renewable energy source 4, storage battery 5, voltage control equipment 6, measuring device 7, power cutoff device, and load cutoff device will be referred to as "equipment."

The grid stabilization system 8 is connected to the equipment via the communication network shown by the dashed line in Figure 1. Based on the measurement results of the measuring device 7, if the grid stabilization system 8 determines that a fault has occurred in the power system, it calculates the control content, including the control target and the control quantity for the control target, which should be controlled in order to resolve the grid abnormal conditions such as overload and abnormal voltage that occur during fault removal. The grid stabilization system 8 then transmits (commands) the control content to the control target equipment, making it possible to resolve the grid abnormal conditions that occur after the fault is removed.

Figure 2 is a block diagram showing the configuration of the system stabilization system 8 according to this first embodiment. The system stabilization system 8 in Figure 2 comprises a communication unit 11 which is an acquisition unit, a recording unit 12, an accident occurrence determination unit 13, a model generation unit 14, and a control content calculation unit 15.

The communication unit 11 receives and acquires measurement information of the power system sequentially (for example, periodically) from the measuring device 7. The communication unit 11 also transmits (commands) the control content, which is the calculation result of the control content calculation unit 15, to the equipment to be controlled.

The recording unit 12 records measurement information acquired by the communication unit 11, power system equipment information, calculation results from the control content calculation unit 15, and the equipment's past control history (e.g., history of controlled quantities). The equipment information includes, for example, the connection relationships between equipment and the impedance and reactance between equipment.

The fault occurrence determination unit 13 determines whether or not a fault has occurred in the power system based on the measurement information. Generally, when a fault occurs in the power system, the voltage, current, and power flow change rapidly, and the protective relay activates. Therefore, the fault occurrence determination unit 13 may determine whether or not the protective relay has activated based on the measurement information, and if it determines that the protective relay has activated, it may determine that a fault has occurred in the power system.

The model generation unit 14 generates a system model based on measurement information and equipment information when the accident occurrence determination unit 13 determines that an accident has occurred. The system model is a model that shows the state of the power system. Conceptually, the system model is a model that shows the connection relationships and operating states of equipment, with impedance between equipment, generated power, and power consumption attached, as shown in Figures 3 <a> to <p>. In reality, the system model includes impedance between equipment, generated power, and power consumption, and is represented by multiple equations that show the relationships between equipment according to the physical laws of the power system.

According to the system model, for example, the voltage, current, and power flow status of the power system, the amount of power generated by generator 2, the load amount of load 3, and the operating status of renewable energy source 4, storage battery 5, and voltage control equipment 6 can be calculated. When the model generation unit 14 generates a system model based on measurement information and equipment information when an accident occurs in the power system, a system model is generated in which the transmission lines or transformers are opened to resolve the accident.

The control content calculation unit 15 determines whether or not an overload or abnormal voltage occurs based on the system model. For example, if the power system state indicated by the system model is a predetermined power system state (for example, a predetermined state where transmission lines are open), the control content calculation unit 15 may determine that an overload or abnormal voltage occurs. Alternatively, for example, if the calculation result of the system model using measurement information indicates predetermined voltage, current, and power flow states, and predetermined operating states of equipment, the control content calculation unit 15 may determine that an overload or abnormal voltage occurs.

When the control content calculation unit 15 determines that an overload or abnormal voltage has occurred, it calculates the control content, including the controlled object and the controlled quantity of the controlled object, based on the system model and equipment information, using optimal power flow calculation (hereinafter sometimes referred to as "OPF").

The control includes a tripping amount, which is the control variable of at least one of the generator 2 and load 3 that are being controlled. In other words, the control includes a tripping amount, which is the control variable of at least one of the generator 2 and load 3.

Furthermore, in this embodiment 1, the control content further includes at least one of the following: the interruption amount, which is the control amount of the renewable energy power source 4 that is the target of control; and the active power and reactive power, which are the control amounts of the renewable energy power source 4, the storage battery 5, and the voltage control device 6 that are the targets of control. In other words, the control content further includes at least one of the following: the interruption amount of the renewable energy power source 4; the active power of the renewable energy power source 4; the reactive power of the renewable energy power source 4; the active power of the storage battery 5; the reactive power of the storage battery 5; the active power of the voltage control device 6; and the reactive power of the voltage control device 6. The calculation of the control content will be explained in detail later.

The control content calculation unit 15 discretizes the control variable as needed. The discretization of the control variable will be explained in detail later.

<Calculation of control content>
Next, we will explain the calculation of the control content using the OPF in the control content calculation unit 15. The OPF is a calculation that finds the value of a variable that minimizes the objective function, which is expressed by the variable, under the constraints. In the following explanation, the objective function, constraints, and OPF will be explained in this order.

<Purpose Discount>
In the following explanation, the objective function is represented as f(x, u, z). The variable x is the set of voltage solutions, for example, a voltage vector composed of the magnitude and phase angle of the bus voltage.

The variable u is a control variable, and is a set of variables that can be controlled by a control system such as the grid stabilization system 8. In this embodiment 1, the variable u includes the amount of power cutoff to the generator 2, load 3, and renewable energy source 4 by the power cutoff device or load cutoff device, and the active power and reactive power of the renewable energy source 4, storage battery 5, and voltage control equipment 6.

The variable z is a dependent variable and is a set of variables determined by the determination of variable u. For example, variable z includes the active and reactive power flows of the transmission line, which are determined by the determination of the interruption amounts of generator 2, load 3, and renewable energy source 4.

The objective function f(x, u, z) in this embodiment 1 is a function for optimizing a certain item of a power system. Several examples of objective functions are described below.

<Objective function for the first example>
The objective function in the first example is an objective function for minimizing the amount of power cutoff to generator 2, load 3, and renewable energy source 4 by a power cutoff device or load cutoff device, and is expressed as shown in equation (1) below. Note that the variables x, u, and z are omitted on the right-hand side of equation (1), and similarly, the variables x, u, and z may be omitted on the right-hand side of other equations. Also, due to the notation constraints in the specification, letters that are expressed as subscripts in the equations are expressed as simple subscripts in the specification.

R ⁱ _Gcur , R ⁱ _Lcur , and R ⁱ _REScur are the interruption amounts for the generator (i), load (i), and renewable energy source (i). ^{P i} _G0 , P ⁱ _L0 , and P ⁱ _RES0 are the steady-state active power for the generator (i), load (i), and renewable energy source (i). _{K G1} , K _L1 , and K _RES1 are the weighting coefficients of the objective function. Since the interruption amount is expressed as the product of the interruption rate and the steady-state active power, the above objective function may also be expressed as shown in equation (2) below.

R ⁱ _G , R ⁱ _L , and R ⁱ _RES are the interruption rates for the generator (i), load (i), and renewable energy source (i).

<Objective function in the second example>
The objective function in the second example is an objective function for minimizing the amount of change in output of the renewable energy power source 4, the storage battery 5, and the voltage control equipment 6, whose output is controlled by output commands from the grid stabilization system 8, and is expressed as shown in equation (3) below. In this example, the voltage control equipment 6 includes, but is not limited to, phase adjustment equipment, SVC, and STATCOM.

P ⁱ _RES and P ⁱ _RES0 represent the active power and steady-state active power of the renewable energy source (i). ^{P i} _ESS and P ⁱ _ESS0 represent the active power and steady-state active power of the battery (i). Q ⁱ _RES , Q ⁱ _ESS , Q ⁱ _SCShS , Q ⁱ _SVC , and Q ⁱ _STATCOM represent the reactive power of the renewable energy source (i), battery (i), phase-shifting equipment (i), SVC (i), and STATCOM (i). ^{Q i} _RES0 , Q ⁱ _ESS0 , Q ⁱ _SCShS0 , Q ⁱ _SVC0 , and Q ⁱ _STATCOM0 represent the steady-state reactive power of the renewable energy source (i), battery (i), phase-shifting equipment (i), SVC (i), and STATCOM (i). K _{RES, P} , K _{RES, Q} , K _{ESS, P} , K _{ESS, Q} , K _{SCShR, Q} , K _{SVC, Q} , K _{STATCOM, Q} are the weight coefficients of the objective function.

<Objective function for the third example>
The objective function in the third example is the objective function for minimizing the voltage and power flow violations, and is expressed as shown in equation (4) below.

^Vi _vio , ^Vi , ^Vi _max , and ^Vi _min are the voltage violation, voltage, maximum voltage, and minimum voltage of node (i). ^Si _vio , ^Si , and ^Si _max are the apparent power flow violation, apparent power flow, and apparent power capacity of transmission line (i). Instead of the absolute values in equations (3) and (4) (e.g., |P ⁱ _RES0 - ^Pi _RES |), the squared values of the values inside the absolute values (e.g., (P ⁱ _RES0 - ^Pi _RES ) ^² ) may be used.

The above describes an example of an objective function according to this embodiment 1, but it is not limited to the above example. For example, the objective function according to this embodiment 1 may be an objective function for minimizing the fuel cost of the generator 2, an objective function for minimizing transmission losses, or an objective function for minimizing the voltage deviation from the target voltage. The objective function may be changed as appropriate according to the user's operational objectives. Furthermore, the objective function according to this embodiment 1 may be an objective function such as K _A f _A (x, u, z) + K _B f _B (x, u, z), which is a combination of two or more objective functions such as _{f A} (x, u, z) and f _B (x, u, z) using two or more weighting coefficients such as K A and K _B.

<Restrictions>
Constraints (also called constraint equations) are expressed by at least one of two inequalities, such as g _A (x, u, z) ≤ 0, or equalities, such as h _A (x, u, z) = 0, which the variables x, u, and z must satisfy. Examples of inequality constraints include capacity constraints for generator 2, renewable energy source 4, and battery 5, and upper limits on the amount of power cutoff for generator 2, load 3, and renewable energy source 4. An example of an equality constraint is the power flow equation (also called the state equation).

Note that constraints that can substitute for the objective function may be used. For example, instead of using the objective function in the third example, the upper and lower voltage limit constraint (V ⁱ _min ≤ V ⁱ ≤ V ⁱ _max ) and the apparent power flow constraint (0 ≤ Si ^≤ Si ⁱ _max ) may be used.

<OPF>
The objective function and constraints described above are described not only by the variable x, u, and z in the OPF, but also by the parameters that are fixed in the OPF. The fixed parameters include values based on the system model and equipment information, such as constants of the power system equipment, line impedance, upper and lower limits of the bus voltage, upper and lower limits of the active and reactive power output of generator 2, and upper and lower limits of the equipment capacity.

The control content calculation unit 15 performs an operation to find the variables x, u, and z that minimize the objective function under the constraints by performing an OPF (Operational Process Firmware). For the OPF solution, methods such as the simplex method, interior-point method, or principal-dual interior-point method may be used, or metaheuristics such as genetic algorithms and particle swarm optimization (PSO) may be used, or other solution methods may be used.

The variables x, u, and z obtained by the OPF (Output Process Filter) can be used to minimize the objective function. For example, the variables x, u, and z obtained by the OPF of an objective function combining the objective function of the first example and the objective function of the third example can reduce overload and abnormal voltage by minimizing voltage violations and power flow violations while minimizing the amount of cutoffs to the generator 2, load 3, and renewable energy source 4. The variables x, u, and z obtained by the OPF of the objective function of the first example and the constraints corresponding to the objective function of the third example (V ⁱ _min ≤ V ⁱ ≤ V ⁱ _max , 0 ≤ S ⁱ ≤ S ⁱ _max ) can also be similarly minimized and reduced.

For example, the variables x, u, and z obtained by the OPF of an objective function combining the objective function of the second example and the objective function of the third example can reduce overload and abnormal voltage by minimizing voltage violations and power flow violations while minimizing the change from the steady state of the active and reactive power outputs of the renewable energy source 4, the storage battery 5, and the voltage control device 6. The variables x, u, and z obtained by the OPF of the objective function of the second example and the constraints corresponding to the objective function of the third example (V ⁱ _min ≤ V ⁱ ≤ V ⁱ _max , 0 ≤ Si ^≤ Si ⁱ _max ) can also be minimized and reduced in a similar manner.

The variable u includes control content, which includes the controlled object and the controlled quantity of the controlled object. In this embodiment 1, it includes the interruption amounts of the generator 2, load 3, and renewable energy source 4, and the active power and reactive power of the renewable energy source 4, storage battery 5, and voltage control device 6. Since the interruption amount and the interruption rate have a one-to-one relationship and are substantially the same, the controlled quantity is substantially the same as the interruption amount of the generator 2, load 3, and renewable energy source 4 and the interruption rate of the generator 2, load 3, and renewable energy source 4. Therefore, the interruption amount may be a broader concept that includes the interruption rate.

The interruption rates of the generator 2, load 3, and renewable energy source 4 obtained by the OPF may be discrete values such as 0 or 1, or continuous values such as 0 to 1. Furthermore, when simulating by aggregating multiple generators 2, load 3, and renewable energy source 4, the interruption amounts of the generators 2, load 3, and renewable energy source 4 obtained by the OPF may be discrete values such as 0, the steady-state value of a single device, or the sum of combinations thereof, or continuous values such as 0 to the steady-state value after aggregation. Additionally, the active power and reactive power of the renewable energy source 4, storage battery 5, and voltage control device 6 obtained by the OPF may also be discrete or continuous values.

<Discretization of the controlled variable>
The control content calculation unit 15 discretizes the control quantity as needed. For example, the generator 2, load 3, and renewable energy source 4 will be controlled to either shut off (shutting off rate 1) or not shut off (shutting off rate 0). Also, when multiple generators 2, loads 3, and renewable energy source 4 are aggregated, control will be performed in increments of the shutoff amount corresponding to one piece of equipment. Furthermore, some renewable energy source 4, storage battery 5, and voltage control equipment 6 can output to any value, while others can only adjust the output in discrete values, such as in increments of 10 kW. In particular, the phase adjustment equipment of the voltage control equipment 6 can only adjust the output in increments of the capacity of each power capacitor and shunt reactor. In situations like the above, if the control quantity obtained by the OPF is a continuous value, the control content calculation unit 15 may discretize the control quantity and convert it into a discrete value control quantity actually used by the controlled object.

For example, _{the control content calculation unit 15 may discretize the control variable by rounding, setting RiG = 0 when 0 ≤ RiG < 0.5 and RiG =} ^{1 when} _0.5 ^{≤ RiG} _≤ 1, or it may discretize the control variable using a threshold different from the rounding threshold (0.5).

<Operation>
Figure 4 is a flowchart illustrating the operation of the power grid stabilization system 8 according to this embodiment 1, i.e., the power grid stabilization method.

In step S1, the communication unit 11 sequentially receives and acquires measurement information of the power system from the measuring device 7.

In step S2, the fault occurrence determination unit 13 determines whether or not a fault has occurred in the power system based on the measurement information. If it is determined that a fault has occurred in the power system, the process proceeds to step S3; if it is not determined that a fault has occurred in the power system, the process proceeds to step S1.

In step S3, the model generation unit 14 generates a system model based on the measurement information and equipment information.

In step S4, the control content calculation unit 15 determines whether an overload or abnormal voltage occurs based on the system model. If it is determined that an overload or abnormal voltage occurs, the process proceeds to step S5; if it is not determined that an overload or abnormal voltage occurs, the process proceeds to step S1.

In step S5, the control content calculation unit 15 calculates the control content, including the controlled object and the controlled quantity of the controlled object, using the OPF based on the system model and equipment information. In this embodiment 1, the control content includes the amount of power cutoff for the generator 2, load 3, and renewable energy source 4 by the power cutoff device or load cutoff device, and the active power and reactive power of the renewable energy source 4, storage battery 5, and voltage control equipment 6.

In step S6, the control content calculation unit 15 discretizes the control quantity as necessary.

In step S7, the communication unit 11 transmits the control content, including the discretized control quantity and the controlled object as needed, to the equipment determined to be the controlled object. As a result, the equipment determined to be the controlled object performs control based on the control quantity. After that, the operation shown in Figure 4 is completed.

<Summary of Embodiment 1>
According to the power grid stabilization system 8 of this embodiment 1 described above, when it is determined that an overload or abnormal voltage has occurred based on the power grid model, the control content, including the controlled object and the controlled amount, is calculated by optimal power flow calculation based on the power grid model and equipment information. The control content includes the interruption amount (interruption rate) of the generator 2 and the load 3. With this configuration, it is possible to appropriately determine the generator 2 and the load 3 to be controlled, and their interruption amount (interruption rate), while reducing the controlled amount and reducing voltage and power flow violations.

Furthermore, in this embodiment 1, the control content further includes at least one of the following: the amount of interruption (interruption rate) of the renewable energy power source 4, and the active power and reactive power of the renewable energy power source 4, the storage battery 5, and the voltage control device 6. With this configuration, it is possible to appropriately determine the amount of interruption (interruption rate) of the renewable energy power source 4 while reducing the amount of control, as well as the amount of voltage violations and power flow violations.

<Embodiment 2>
Figure 5 is a block diagram showing the configuration of the system stabilization system 8 according to this second embodiment. The configuration in Figure 5 is the same as the configuration in Figure 2, with the addition of a sensitivity calculation unit 16.

The sensitivity calculation unit 16 calculates the sensitivity of at least one of the power flow in the power transmission lines of the power system and the voltage of the busbars of the power system, based on the control content calculated by the control content calculation unit 15. For example, the sensitivity calculation unit 16 calculates the sensitivity to the control quantity of the controlled object included in the control content, or the sensitivity to the control quantity of the controlled object node included in the control content, by numerical analysis simulation.

In the following, the first calculation example explains how to calculate the sensitivity to the active power (P ⁽ⁱ⁾ _G ) and reactive power (Q ⁽ⁱ⁾ _G ) of the generator (i), and the second calculation example explains how to calculate the sensitivity to the active power (P ⁽ⁱ⁾ ) and reactive power (Q ⁽ⁱ⁾ ) of the controlled node (i). Note that even if the controlled object is not a generator but other equipment such as load 3 or renewable energy source 4, the sensitivity can be calculated in the same manner as below.

<First calculation example>
The sensitivity calculation unit 16 performs power flow calculations, which are system calculations, by changing the operating state (output state) of one controlled object in a system model where an overload or abnormal voltage is determined to occur. For example, if the controlled object of the control content is a generator (i) and the controlled amount of the control content is an active power (P ⁽ⁱ⁾ _G ) of 100 MW, the sensitivity calculation unit 16 may change the active power (P ⁽ⁱ⁾ _G ) to 10 MW or to 100 MW. In power flow calculations, unlike OPF, the generated power of generator 2 and the power consumption of load 3 are fixed values, and the power flow flowing through transmission lines, etc., as well as the voltage and phase of each part, are calculated based on these fixed values.

The sensitivity calculation unit 16 calculates the changes in power flow in the transmission line where overload occurs and the changes in voltage of the busbar where abnormal voltage occurs by performing the above power flow calculation in the simulation. For example, when the change in active power of the generator (i) is ΔP ⁽ⁱ⁾ _G , ΔP ^(k) _f , ΔQ(k) _f , and ΔS ^{(k )} _f are calculated as changes in active power flow, reactive power flow, and apparent power flow of the transmission line (k), and ΔV ^(j) is calculated as the voltage change of the busbar (j). In this case, the sensitivity calculation unit 16 calculates the sensitivity of ΔP ^(k) _f , ΔQ(k) _f , ΔS ^{( k} ) _f , and ΔV ^(j) to ΔP ⁽ⁱ⁾ _G using the following equation (5).

For example, consider a case where, when the active power of a generator (i) changes by ΔQ ⁽ⁱ⁾ _G , ΔP(k) _f , ΔQ(k ⁾ _f , and ΔS ^(k) _f are calculated as changes in the active power flow, reactive power flow, and apparent power flow of a transmission line ^(k ), and ΔV ^(j) is calculated as the voltage change of a busbar (j). In this case, the sensitivity calculation unit 16 calculates the sensitivity of ΔP ^(k) _f , ΔQ(k) _f , ΔS( ^{k )} _f , and ΔV ^(j) to ΔQ( ⁱ⁾ _G using the following equation (6).

The sensitivity calculation unit 16 calculates the sensitivity for each controlled object, each transmission line where an overload occurs, and each busbar where an abnormal voltage occurs. The sensitivity calculation unit 16 may perform the sensitivity calculation multiple times for each controlled object and each transmission line or busbar. For example, the sensitivity calculation unit 16 may perform the sensitivity calculation multiple times while adjusting the degree of change in the operating state of the equipment in the simulation, and obtain the average or median of the multiple sensitivities obtained from the multiple calculation results as the final sensitivity. Specifically, if the controlled object of the control content is a generator (i) and the controlled amount of the control content is an active power (P ⁽ⁱ⁾ _G ) of 100 MW, the sensitivity calculation unit 16 calculates nine sensitivities while changing the active power (P ⁽ⁱ⁾ _G ) from -200 MW to 200 MW in 50 MW increments. The sensitivity calculation unit 16 may then obtain the average value of the nine sensitivities as the final sensitivity.

<Second calculation example>
The sensitivity calculation unit 16 calculates a voltage sensitivity matrix that shows the change in the voltage of node (i) in response to changes in active power (P ⁽ⁱ⁾ ) and reactive power (Q ⁽ⁱ⁾ ) flowing into node (i) to be controlled. For example, the sensitivity calculation unit 16 calculates the voltage sensitivity matrix by calculating the partial derivative of the power flow equation. The power flow equation is an equation that shows the relationship between the active power and reactive power flowing into a node and the voltage of the node, and is expressed as shown in equation (7) below.

P ⁽ⁱ⁾ and Q ⁽ⁱ⁾ are the active and reactive powers flowing into node (i), respectively. V^ ⁽ⁱ⁾ (^* means that a dot is placed above the preceding letter) is the voltage at node (i) and is represented as V ⁽ⁱ⁾ exp(jV ⁽ⁱ⁾ ). Y^ _iik is the node admittance matrix.

When we partially differentiate equation (7), which represents the tidal equation, with respect to the real part and imaginary part with respect to V ⁽ⁱ⁾ and δ ⁽ⁱ⁾ , we obtain equation (8).

Equation (8) represents the changes in active and reactive power (ΔP ⁽ⁱ⁾ , ΔQ ⁽ⁱ⁾ ) at node (i) in response to the change in voltage (ΔV ⁽ⁱ⁾ , Δδ ⁽ⁱ⁾ ) at node (i). Matrix J is called the Jacobian matrix of the tidal equation. Multiplying equation (8) by the inverse matrix ^J⁻¹ of matrix J from the left yields equation (9).

Equation (9) represents the change in voltage at node (i) (ΔV ⁽ⁱ⁾ , Δδ ⁽ⁱ⁾ ) in response to the change in active and reactive power at node (i) (ΔP ⁽ⁱ⁾ , ΔQ ⁽ⁱ⁾ ). Therefore, the inverse matrix J ^-1 of the Jacobian matrix is the voltage sensitivity matrix. For example, if node (i) is the node to be controlled and node (j) is the node where an abnormal voltage occurs, the change in voltage at node (j) (ΔV( ^j )) in response to the change in active and reactive power at node (i) (ΔP ⁽ⁱ⁾ , ΔQ ⁽ⁱ⁾ ) is expressed as shown in equation (10).

The sensitivity calculation unit 16 not only calculates the voltage sensitivity matrix (J ^{- 1} ), but also calculates a power flow sensitivity matrix that represents the changes in active power flow and reactive power flow of the transmission line in response to changes in the voltage of the node. For example, in a model like the one in Figure 6, the following relationship (11) holds between the active power flow (P ^(k) _f ) and reactive power flow (Q ^(k) _f ) on the node (i) side flowing through the transmission line (k), the voltage of node (i) (V^・⁽ⁱ⁾ ), and the voltage of node (j) (V^・^(j) ).

y^ _k is the admittance of the transmission line (k). Partially differentiating equation (11) with respect to the real and imaginary parts with respect to V ⁽ⁱ⁾ , δ ⁽ⁱ⁾ , V ^(j) , and δ ^(j) , we obtain equation (12).

Equation (12) represents the changes in active and reactive power flow (ΔP ^{( k} ) _{f, ΔQ} ⁽ k) _f ) in the transmission line (k) in response to the change in voltage (ΔV(i), Δδ ⁽ i)) at node (i). Therefore, matrix P is the power flow sensitivity matrix.

Substituting equation (9) into equation (12), we obtain the following equation (13), which represents the changes in active power flow and reactive power flow (ΔP ^(k) _f , ΔQ ^(k) f) in the transmission line (k) with respect to the changes in active power and reactive power (ΔP ⁽ⁱ⁾ , ΔQ ⁽ⁱ ₎ ) in node (i).

The sensitivity calculation unit 16 calculates the sensitivity using equation (13), which combines the voltage sensitivity matrix (J ^{- 1} ) and the power flow sensitivity matrix (P). For example, if the node to be controlled is node (i) and the transmission line where the overload occurred is transmission line (k), the changes in active power flow and reactive power flow of transmission line (k) (ΔP ^(k) _f , ΔQ ^(k) _f ) in response to the changes in active power and reactive power of node (i) (ΔP ⁽ⁱ⁾ , ΔQ ⁽ⁱ⁾ ) are expressed as shown in equations (14) and (15).

<Summary of Embodiment 2>
The grid stabilization system 8 may control not only the facilities of the general transmission and distribution company (power company) that operates the grid stabilization system 8, but also the facilities of power generators and general consumers. When controlling the facilities of power generators and general consumers, the operator of the grid stabilization system 8 may have to explain the appropriateness of the control content to the power generators and consumers.

Therefore, in the grid stabilization system 8 according to this second embodiment, the sensitivity of at least one of the power flow in the power transmission lines of the power system and the voltage of the power busbars of the power system is calculated based on the control content. With this configuration, for example, the operator of the grid stabilization system 8 can explain the effectiveness and appropriateness of the control content in resolving overload and abnormal voltage by referring to the calculated sensitivity.

Furthermore, the sensitivity calculation unit 16 may also calculate sensitivity for equipment other than those mentioned above, such as power transmission lines and busbars. In this case, for example, the operator of the grid stabilization system 8 can refer to the calculated sensitivity to explain why the equipment in question was not included as a control target in resolving overload and abnormal voltage. In addition, the grid stabilization system 8 may use AI (Artificial Intelligence) to machine learn (train) an explanation of the validity of the control content based on the calculated sensitivity, so that it can present such an explanation to the operator of the grid stabilization system 8.

<Embodiment 3>
Figure 7 is a block diagram showing the configuration of the system stabilization system 8 according to this third embodiment. The configuration in Figure 7 is the same as the configuration in Figure 2, with the addition of a coefficient setting unit 17.

In this embodiment 3, the first to fourth configurations described below make it possible to suppress the concentration of control on a specific piece of equipment among the controlled objects, or to make a specific piece of equipment among the controlled objects more difficult or easier to control. Note that this embodiment 3 only needs to include at least one of the first to fourth configurations.

<First configuration>
In the first configuration, the coefficient setting unit 17 sets weight coefficients to adjust the control values, which are at least one of the control quantities and control counts for each of the multiple controlled objects, and the control content calculation unit 15 uses the objective function including the set weight coefficients in the OPF. For example, the coefficient setting unit 17 sets the weight coefficients ^WiPG , _WiPL , ^{and WiPRES} to adjust the control values of the generator 2, load ₃ , and renewable energy source ₄ ^, respectively. In the following description, if the weight coefficients ^WiPG , _WiPL , _and ^WiPRES are not distinguished _, they will be written as weight coefficient W. The control content calculation unit 15 _uses the objective function represented by the following equation (16), which includes equation (2) and the weight coefficients ^WiPG , ^WiPL , _and ^WiPRES _, in the OPF.

For example, the larger the weighting _coefficient ^WiPG in equation (16), the smaller the control value of generator (i), and the less likely generator (i) is to be controlled. Conversely, the smaller the weighting _coefficient ^WiPG in equation (16), the larger the control value of generator (i), and the more likely generator (i) is to be controlled.

Therefore, the coefficient setting unit 17 sets the weight coefficient W of the controlled object to a large value so that the control value of the controlled object decreases as its past control value increases. On the other hand, the coefficient setting unit 17 sets the weight coefficient W of the controlled object to a small value so that the control value of the controlled object increases as its past control value increases.

This first configuration makes it possible to suppress the concentration of control on specific equipment among the controlled objects, thereby making the control of the controlled objects fairer (more uniform).

Furthermore, the objective function including the weight coefficients set by the control content calculation unit 15 is not limited to equation (16), but may also include, for example, an objective function including equation (3) and the weight coefficients. In addition, the coefficient setting unit 17 may set the weight coefficients determined by trial and error by the operator of the system stabilization system 8, or it may set the weight coefficients calculated by the following equations (17) and (18), or it may set weight coefficients other than these.

P ⁱ _Gtotal is the cumulative control amount in the operation of generator (i) to date, and a _G , b _G , and c _G are parameters for calculating the weight coefficients.

<Second configuration>
In the second configuration, similar to the first configuration, the coefficient setting unit 17 sets weight coefficients W to adjust the control values of each of the multiple controlled objects, and the control content calculation unit 15 uses the objective function including the set weight coefficients W in the OPF. However, the coefficient setting unit 17 sets the weight coefficients W of the controlled objects in such a way that predetermined equipment is less likely to be selected as a controlled object or is more likely to be selected, or that the control value becomes smaller or larger when selected.

For example, if equipment is designated as equipment for which continued operation or stable power supply is desirable, the coefficient setting unit 17 sets the weighting coefficient W of the controlled equipment to a large value so that the equipment is less likely to be selected as a controlled equipment and the controlled value is smaller than that of other equipment. Equipment for which continued operation or stable power supply is desirable is, for example, a hospital or a mass transformer power supply necessary for stabilizing the power system.

On the other hand, if equipment is designated in advance as equipment that is preferable to be controlled, the coefficient setting unit 17 sets the weighting coefficient W of the equipment to be controlled to a small value so that the equipment is more likely to be selected as the equipment to be controlled and the control value is larger than that of other equipment. Equipment that is preferable to be controlled is, for example, a power plant that recovers quickly even after stopping, or the cost required for recovery is low.

This second configuration makes it possible to make certain pieces of equipment among those being controlled more difficult or easier to control.

<Third configuration>
In the third configuration, the control content calculation unit 15 generates an objective function to minimize the variation in the control quantities of multiple controlled objects and uses it in the OPF. For example, when the control content calculation unit 15 performs OPF using a certain objective function, it performs OPF using an objective function that minimizes the variation in the control quantities of multiple controlled objects. The objective function that minimizes the variation in the control quantities of multiple controlled objects can be expressed, for example, as shown in equation (19) below.

K _G3 , K _L3 , and K _RES3 are weighting coefficients of the objective function. These weighting coefficients may be constant or may be changed based on the history of the controlled quantities of multiple controlled objects. ^σ² _PG , ^σ² _PL , and ^σ² _PRES are variances that show the variation in the amount of interruption of the generator 2, load 3, and renewable energy source 4. The variance of the amount of interruption of the generator 2 can be expressed, for example, as shown in equation (20), and the variances of the amount of interruption of the load 3 and renewable energy source 4 can be expressed similarly.

In the above explanation, the variation in the controlled quantity across multiple controlled objects was the variation in the respective interruption amounts of generator 2, load 3, and renewable energy source 4. However, it is not limited to this, and could be, for example, the variation in the interruption amount of generator 2, load 3, and renewable energy source 4 as a whole. Also, in the above explanation, the variation in the controlled quantity was the variance of the controlled quantity, but it is not limited to this, and could be, for example, the standard deviation, mean deviation, or the difference between the maximum and minimum values of the controlled quantity.

This third configuration makes it possible to suppress the concentration of control on specific equipment among the controlled objects, thereby making the control of the controlled objects fairer (more uniform).

<Fourth configuration>
In the fourth configuration, the control content calculation unit 15 adjusts the control quantities of multiple controlled objects based on the history of the control quantities of multiple controlled objects when the control effects of multiple controlled objects correspond to each other. The correspondence of the control effects of multiple controlled objects includes, for example, at least one of the following: the electrical distance between the multiple controlled objects is below a threshold, and the difference between the power flow change and voltage change of the multiple controlled objects is below a threshold.

For example, if the control effect of the first controlled object corresponds to the control effect of the second controlled object, the control content calculation unit 15 may determine from the history of the control quantities whether the total value of the control quantities of the first controlled object up to date is greater than the first threshold, and whether the total value of the control quantities of the second controlled object up to date is less than the second threshold, which is less than the first threshold. If the control content calculation unit 15 determines that the total value of the first controlled object is greater than the first threshold and the total value of the second controlled object is less than the second threshold, it may replace the current control quantity of the first controlled object with the current control quantity of the second controlled object. Alternatively, the control content calculation unit 15 may set the average value of the control quantity of the first controlled object and the control quantity of the second controlled object obtained in the current OPF as the control quantities of the first and second controlled objects.

Furthermore, for example, if the control effect of the first controlled object corresponds to the control effect of the second controlled object, the control content calculation unit 15 may, according to the rotation table, replace the control amount of the first controlled object obtained in this OPF with the control amount of the second controlled object obtained in this OPF.

This fourth configuration makes it possible to suppress the concentration of control on specific equipment among the controlled objects, thereby making the control of the controlled objects fairer (more uniform).

<Operation>
Figure 8 is a flowchart illustrating the operation of the system stabilization system 8 according to this embodiment 3. The operation in Figure 8 is similar to the operation in Figure 4, but with step S11 added and steps S5 and S6 of Figure 4 changed to steps S5a and S6a. Therefore, the following explanation will mainly focus on steps S11, S5a, and S6a.

If it is determined in step S4 that an overload or abnormal voltage has occurred, the process proceeds to step S11. In step S11, the coefficient setting unit 17 sets the weight coefficients described in the first and second configurations. After that, the process proceeds to step S5a.

In step S5a, the control content calculation unit 15 calculates the control content, including the controlled object and the controlled quantity of the controlled object, using the OPF based on the system model and equipment information. The objective function used in the OPF includes, for example, at least one of the objective functions described in the first to third configurations.

In step S6a, the control content calculation unit 15 adjusts the control quantity as described in the fourth configuration, or discretizes the control quantity, if necessary.

<Summary of Embodiment 3>
As described above, the system stabilization system 8 according to this embodiment 3 can suppress the concentration of control on a specific piece of equipment among the controlled objects, or make a specific piece of equipment among the controlled objects difficult or easy to control, through the first to fourth configurations. Therefore, the controlled objects can be controlled appropriately.

<Embodiment 4>
Figure 9 is a schematic diagram showing a power system using the power system stabilization system 8 according to this fourth embodiment. The power system stabilization system 8 in Figure 9 comprises a central computing unit 8a and one or more slave station devices 8b capable of communicating with the central computing unit 8a. The power system in Figure 9 is the same as the power system in Figure 1, except for this point.

The central processing unit 8a acquires measurement information of the power system from the measurement device 7 via the slave station device 8b and generates a control table that associates predetermined fault patterns with control contents. Based on the measurement information, the slave station device 8b determines that a fault pattern from the control table has occurred in the power system, and then determines the control contents associated with that fault pattern in the control table. The slave station device 8b then transmits (commands) the control contents to the equipment to be controlled, making it possible to resolve the system abnormality state that occurs after the fault has been cleared.

<Central processing unit 8a>
Figure 10 is a block diagram showing the configuration of the central processing unit 8a. The central processing unit 8a in Figure 10 includes a first acquisition unit, which is a communication unit 21, a recording unit 22, a hypothetical accident setting unit 23, a model generation unit 24, and a control content calculation unit 25.

The communication unit 21 receives and acquires power system measurement information from the measurement device 7 sequentially (for example, periodically) via the slave station device 8b. The communication unit 21 also appropriately transmits the control table generated by the central processing unit 8a to the slave station device 8b.

The recording unit 22 records the measurement information collected by the communication unit 21, the equipment information of the power system, the calculation results of the control content calculation unit 25, and the equipment's past control history (for example, the history of the controlled quantity).

The assumed fault setting unit 23 sets multiple fault patterns that may occur in the current power system based on measurement information and equipment information. These fault patterns include, for example, a predetermined first transmission line experiencing a ground fault or short circuit due to a lightning strike, fallen tree, or contact with a flying object, and a predetermined second transmission line being opened to mitigate the effects of the ground fault or short circuit on the first transmission line. Note that the multiple fault patterns do not necessarily have to be predetermined by the assumed fault setting unit 23; they may also be predetermined by the operator of the system stabilization system 8.

The model generation unit 24 generates a system model for each of the multiple accident patterns based on measurement information, equipment information, and a predetermined set of accident patterns. The generation of system models by the model generation unit 24 is the same as the generation of system models by the model generation unit 14 in Figure 2. In the system models generated by the model generation unit 24, for example, the parts of the connection relationships between equipment that are disconnected differ depending on the accident pattern.

The control content calculation unit 25, similar to the control content calculation unit 15 described in Embodiment 1, determines whether an overload or abnormal voltage occurs based on the fault pattern system model. If the control content calculation unit 25 determines that an overload or abnormal voltage occurs, it calculates the control content using the OPF based on the system model and equipment information, similar to the control content calculation unit 15 described in Embodiment 1. The control content only needs to include a break-off amount, which is a control quantity of at least one of the controlled generator 2 and load 3, and may also include a break-off amount, which is a control quantity of the controlled renewable energy power source 4, similar to Embodiment 1.

The control content calculation unit 25 generates a control table that associates accident patterns with the control content calculated from those accident patterns. If the control content calculation unit 25 calculates multiple control content from multiple accident patterns, the multiple accident patterns and the multiple control content are associated in the control table.

The components of the central processing unit 8a are not limited to those described above. For example, the central processing unit 8a may further include the sensitivity calculation unit 16 described in Embodiment 2, or the coefficient setting unit 17 described in Embodiment 3.

<Slave station device 8b>
Figure 11 is a block diagram showing the configuration of the slave unit 8b. The slave unit 8b in Figure 11 comprises a second acquisition unit, which is a communication unit 31, a recording unit 32, an accident occurrence determination unit 33, and a control content determination unit 34.

The communication unit 31 receives and acquires measurement information of the power system sequentially (for example, periodically) from the measuring device 7, and transmits the measurement information to the central processing unit 8a as appropriate. The communication unit 31 also receives and acquires control tables from the central processing unit 8a, and transmits (commands) the control content determined by the control content determination unit 34 to the equipment to be controlled.

The recording unit 32 records equipment information of the power system under the jurisdiction of the slave station device 8b, as well as measurement information and control tables acquired by the communication unit 31.

The fault occurrence determination unit 33, similar to the fault occurrence determination unit 13 in Figure 2, determines whether or not a fault pattern of the control table has occurred in the power system based on the measurement information. In this embodiment 4, the fault pattern corresponds to the operating state of the protective relay or an overload or abnormal voltage in the power system.

The control content determination unit 34 determines the control content associated with the accident pattern that has been determined to have occurred, as determined by the control table.

<Operation>
Figure 12 is a flowchart showing the operation of the central processing unit 8a according to this fourth embodiment.

In step S21, the communication unit 21 sequentially receives and acquires power system measurement information from the measuring device 7 via the slave station device 8b.

In step S22, the assumed fault setting unit 23 or the operator sets multiple fault patterns that could occur in the current power system.

In step S23, the model generation unit 24 generates a system model for each of the multiple accident patterns based on the measurement information, equipment information, and multiple accident patterns.

In step S24, the control content calculation unit 25 determines whether an overload or abnormal voltage occurs based on the system model of one fault pattern. If it is determined that an overload or abnormal voltage occurs, the process proceeds to step S25; if it is not determined that an overload or abnormal voltage occurs, the process proceeds to step S26.

In step S25, the control content calculation unit 25 calculates one control content using the OPF based on the system model and equipment information of one fault pattern, and associates one fault pattern with one control content in the control table. The control content determination unit 25 may, if necessary, discretize the control quantities included in the control content, similar to the control content calculation unit 15 in Figure 2.

In step S26, the control content calculation unit 25 determines whether the determination in step S24 was performed for all of the multiple accident patterns. If the determination in step S24 was performed for all of the multiple accident patterns, the process proceeds to step S27. If the determination in step S24 was not performed for all of the multiple accident patterns, the process proceeds to step S24.

In step S27, the communication unit 21 transmits the control table to the slave station device 8b. After that, the operation shown in Figure 12 is completed.

Figure 13 is a flowchart showing the operation of the slave unit 8b according to this fourth embodiment. It is assumed that the slave unit 8b has already received the control table from the central processing unit 8a before performing this operation.

In step S31, the communication unit 31 sequentially receives and acquires measurement information of the power system from the measuring device 7, and transmits the measurement information to the central processing unit 8a as appropriate.

In step S32, the fault occurrence determination unit 33 determines, based on the measurement information, whether or not a fault pattern from the control table has occurred in the power system. If it is determined that a fault pattern has occurred in the power system, the process proceeds to step S33; otherwise, the process proceeds to step S31.

In step S33, the control content determination unit 34 determines the control content associated with the accident pattern determined to have occurred in the control table. The control content determination unit 34 may, if necessary, discretize the control quantities included in the control content, similar to the control content calculation unit 15 in Figure 2.

In step S34, the communication unit 31 transmits the control content to the equipment determined to be controlled. As a result, the equipment determined to be controlled performs control based on the control quantity. After that, the operation shown in Figure 13 is completed.

<Summary of Embodiment 4>
According to the power grid stabilization system 8 of this embodiment 4 described above, the central processing unit 8a can create a control table including control details before a fault occurs in the power grid and transmit the control table to the slave station 8b. Then, when a fault occurs in the power grid, the slave station 8b can determine the control details without communicating with the central processing unit 8a.

This reduces the processing load on the central processing unit 8a after an accident, and also allows for rapid transmission of control information from the slave unit 8b to the controlled object. Therefore, it eliminates the need for a high-performance computer and a wide-area, high-speed communication network. Furthermore, to transmit control information from the slave unit 8b to the controlled object more quickly, it is preferable that the electrical distance between the slave unit 8b and the controlled object is smaller than the electrical distance between the central processing unit 8a and the controlled object.

<Other variations>
The communication unit 11, fault occurrence determination unit 13, model generation unit 14, and control content calculation unit 15 shown in Figure 2 above will be referred to as "communication unit 11, etc." below. The communication unit 11, etc. is implemented by the processing circuit 81 shown in Figure 14. Specifically, the processing circuit 81 includes a communication unit 11 that acquires measurement information of the power system, a fault occurrence determination unit 13 that determines whether or not a fault has occurred in the power system based on the measurement information, a model generation unit 14 that generates a system model based on the measurement information and the equipment information of the power system when it is determined that a fault has occurred, and a control content calculation unit 15 that calculates control content including the controlled object and the controlled quantity of the controlled object by optimal power flow calculation based on the system model and the equipment information when it is determined that an overload or abnormal voltage has occurred based on the system model, and the control content includes a break-off quantity which is at least one of the controlled quantities of the generator and the load, which are the controlled objects. Dedicated hardware may be applied to the processing circuit 81, or a processor that executes a program stored in memory may be applied. Examples of processors include central processing units, processing units, arithmetic units, microprocessors, microcomputers, and DSPs (Digital Signal Processors).

If the processing circuit 81 is dedicated hardware, it may be, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. Each function of the communication unit 11, etc., may be implemented by a circuit with distributed processing circuits, or the functions of each part may be implemented together by a single processing circuit.

When the processing circuit 81 is a processor, the functions of the communication unit 11, etc., are realized in combination with software, etc. Software, etc., may include, for example, software, firmware, or both software and firmware. The software, etc., is written as a program and stored in memory. As shown in Figure 15, the processor 82 applied to the processing circuit 81 realizes the functions of each part by reading and executing the program stored in memory 83. That is, the power grid stabilization system 8, when executed by the processing circuit 81, includes memory 83 for storing a program that will ultimately execute the following steps: acquiring measurement information of the power grid; determining whether or not a fault has occurred in the power grid based on the measurement information; generating a grid model based on the measurement information and power grid equipment information if a fault has been determined to have occurred; and calculating control content, including the controlled object and the controlled quantity of the controlled object, by optimal power flow calculation based on the grid model and equipment information if an overload or abnormal voltage is determined to occur based on the grid model. In other words, this program can be said to cause the computer to execute the procedures and methods of the communication unit 11, etc. Here, memory 83 may be, for example, non-volatile or volatile semiconductor memory such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory), HDD (Hard Disk Drive), magnetic disk, flexible disk, optical disk, compact disk, minidisc, DVD (Digital Versatile Disc), their drive devices, or any storage medium used in the future.

The above describes a configuration in which each function of the communication unit 11, etc., is realized by either hardware or software. However, this is not the only configuration; a configuration in which part of the communication unit 11, etc., is realized by dedicated hardware and another part by software, etc., is also possible. For example, the communication unit 11 can be realized by a processing circuit 81 as dedicated hardware, while the other functions can be realized by a processing circuit 81 as a processor 82 reading and executing a program stored in memory 83.

As described above, the processing circuit 81 can realize each of the above-mentioned functions by hardware, software, or a combination thereof. The components of the grid stabilization system 8 in Figure 5, the grid stabilization system 8 in Figure 7, the central processing unit 8a in Figure 10, and the slave station device 8b in Figure 11 are also the same as described above.

Furthermore, it is possible to freely combine each embodiment and each variation, and to modify or omit each embodiment and each variation as appropriate.

The above explanation is illustrative and not limiting in all respects. It is understood that countless variations not illustrated are conceivable.

2. Generator, 3. Load, 4. Renewable energy source, 5. Storage battery, 6. Voltage control equipment, 8. System stabilization system, 8a. Central computing unit, 8b. Substation equipment, 11, 21, 31. Communication unit, 13, 33. Accident occurrence determination unit, 14, 24. Model generation unit, 15, 25. Control content calculation unit, 16. Sensitivity calculation unit, 17. Coefficient setting unit, 34. Control content determination unit.

Claims (13)

An acquisition unit that acquires measurement information of the power system including the generator and load,
An accident occurrence determination unit that determines whether or not an accident has occurred in the power system based on the measurement information,
When it is determined that the aforementioned accident has occurred, a model generation unit generates a system model based on the measurement information and the power system equipment information,
The system includes a control content calculation unit that, when it is determined that an overload or abnormal voltage has occurred based on the system model, calculates control content including the controlled object and the controlled amount of the controlled object by optimal power flow calculation with the controlled amount of the controlled object as a variable, based on the system model and the equipment information.
The control content includes a cutoff amount which is the control amount of at least one of the generator and the load that are the targets of control.
A power system stabilization system further comprising a sensitivity calculation unit that calculates the sensitivity of at least one of the power flow in the power transmission lines of the power system and the voltage of the busbars of the power system based on the control content described above . A system stabilization system according to claim 1,
The aforementioned power system further includes a renewable energy source, a storage battery, and voltage control equipment.
The aforementioned control contents are:
The control amount of the renewable energy power source that is the target of control is the interruption amount,
A grid stabilization system further comprising at least one of the control quantities of the renewable energy power source, the storage battery, and the voltage control device, which are the controlled objects. A system stabilization system according to claim 1 ,
The aforementioned sensitivity calculation unit,
A grid stabilization system that calculates the sensitivity by changing the operating state of the controlled object and performing grid calculations. A system stabilization system according to claim 1 ,
The aforementioned sensitivity calculation unit,
A grid stabilization system that calculates the sensitivity using a voltage sensitivity matrix, which is the inverse of the Jacobian matrix of the power flow equation and represents the change in the voltage of the node to be controlled in response to changes in the active power and reactive power of the node, and a power flow sensitivity matrix, which represents the change in the active power flow and reactive power flow of the transmission line in response to changes in the voltage of the node. A system stabilization system according to claim 1 ,
The system stabilization system provides a sensitivity calculation unit that presents the sensitivity calculated by the sensitivity calculation unit together with the control content derived by the control content calculation unit. A system stabilization system according to claim 1 or claim 2,
The control content calculation unit is:
A power grid stabilization system that uses an objective function in the optimal power flow calculation to minimize the variation in the controlled quantities of multiple controlled objects. A system stabilization system according to claim 1 or claim 2,
The control content calculation unit is:
A system stabilization system that adjusts the control amounts of multiple controlled objects based on the history of the control amounts of the multiple controlled objects when the control effects of the multiple controlled objects correspond to each other. A system stabilization system according to claim 1 or claim 2,
The system further includes a coefficient setting unit that sets a weighting coefficient for adjusting a control value which is at least one of the control amount and control count for each of the multiple control targets,
The control content calculation unit is a power grid stabilization system that uses the objective function including the weight coefficients in the optimal power flow calculation. A system stabilization system according to claim 8 ,
The coefficient setting unit is,
A system stabilization system that sets the weight coefficient such that the larger the past control value of the controlled object, the smaller the control value of the controlled object becomes, or the smaller the past control value of the controlled object, the larger the control value of the controlled object becomes. A system stabilization system according to claim 8 ,
The coefficient setting unit is,
A system stabilization system that sets the weighting coefficient so that the control value of the controlled object becomes larger or smaller when the controlled object is a predetermined piece of equipment. The central processing unit,
The system comprises a slave station capable of communicating with the aforementioned central processing unit,
The aforementioned central processing unit is
A first acquisition unit that acquires measurement information of the power system including the generator and load,
A model generation unit generates a system model for each of the predetermined fault patterns based on the measurement information, the equipment information of the power system, and a predetermined set of fault patterns.
The system model of the fault pattern determines that an overload or abnormal voltage is occurring, and the system model and the equipment information determine the control content, including the controlled object and the controlled amount of the controlled object, by calculating the control content using an optimal power flow calculation with the controlled amount of the controlled object as a variable, and the system model and the equipment information determine the control content, and the system model includes a control content calculation unit that generates a control table associating the fault pattern with the control content.
The control content includes a cutoff amount which is the control amount of at least one of the generator and the load that are the targets of control.
The aforementioned substation device is,
A second acquisition unit that acquires the aforementioned measurement information and the aforementioned control table,
Based on the measurement information, the power system includes an accident occurrence determination unit that determines whether or not the accident pattern of the control table has occurred,
It includes a control content determination unit that determines the control content associated with the accident pattern that has been determined to have occurred, in the control table,
The aforementioned central processing unit is
A power system stabilization system further comprising a sensitivity calculation unit that calculates the sensitivity of at least one of the power flow in the power transmission lines of the power system and the voltage of the busbars of the power system based on the control content described above . We acquire measurement information of the power system, including generators and loads.
Based on the measurement information, it is determined whether or not an accident has occurred in the power system.
If it is determined that the aforementioned accident has occurred, a system model is generated based on the measurement information and the power system equipment information.
If it is determined that an overload or abnormal voltage occurs based on the system model, the control content, including the controlled object and the controlled amount of the controlled object, is calculated based on the system model and the equipment information by an optimal power flow calculation with the controlled amount of the controlled object as a variable.
The control content includes a cutoff amount which is the control amount of at least one of the generator and the load that are the targets of control.
A power system stabilization method for calculating the sensitivity of at least one of the power flow in the power transmission lines of the power system and the voltage of the busbars of the power system, based on the control content described above . A method for stabilizing a power system stabilization system,
The system stabilization system comprises a central computing unit and a slave unit capable of communicating with the central computing unit.
The aforementioned central processing unit is
We acquire measurement information of the power system, including generators and loads.
Based on the measurement information, the power system equipment information, and a predetermined set of fault patterns, a system model is generated for each of the set of fault patterns.
If it is determined that an overload or abnormal voltage occurs based on the system model of the fault pattern, the control content, including the controlled object and the controlled quantity of the controlled object, is calculated based on the system model and the equipment information by an optimal power flow calculation with the controlled quantity of the controlled object as a variable, and a control table is generated that associates the fault pattern with the control content.
The control content includes a cutoff amount which is the control amount of at least one of the generator and the load that are the targets of control.
The aforementioned substation device is,
The measurement information and the control table are acquired.
Based on the measurement information, it is determined whether the fault pattern in the control table occurred in the power system.
The control content is determined to correspond to the accident pattern that was determined to have occurred in the control table .
The aforementioned central processing unit is
A power system stabilization method for calculating the sensitivity of at least one of the power flow in the power transmission lines of the power system and the voltage of the busbars of the power system, based on the control content described above .