JP6847600B2 - Electronic controller selection method, electronic controller selection program and its recording medium - Google Patents

Description

An embodiment of the present invention relates to an electric control device selection method, an electric control device selection program, and a recording medium thereof in a power system stabilizer.

In general, when an accident occurs in the power system, a sudden imbalance between supply and demand may occur, and the generator in the system may step out. The main cause of step-out of a generator is that the electrical output is low with respect to the mechanical input of the generator, the rotation speed of the generator increases, and the phase relationship with other generators is disrupted. As a factor, it is a phenomenon that stable operation becomes impossible. Therefore, if the electrical output with respect to the mechanical input can be temporarily increased, it is possible to prevent the rotation speed of the generator from decreasing and the phase relationship with other generators from being disrupted.

Therefore, in order to prevent step-out, it is known to limit the power source (hereinafter referred to as electronic control) to shut off the generator whose phase relationship is broken from the system. This electronic control is a system stabilization method that utilizes the effect of temporarily increasing the electrical output of the remaining generators by sharing the power generation output, which is the load sharing of the shut-off generators, with the remaining generators. Is.

By the way, regardless of whether or not the above-mentioned electric control is applied, that is, whether or not the step-out phenomenon occurs, after the accident occurs, a transient voltage drop phenomenon occurs in the system due to the shaking of the generator. obtain. This transient voltage drop phenomenon can be eliminated by electrically controlling a generator having a large internal phase difference angle. As a method for suppressing a transient voltage drop phenomenon, for example, a control method focusing on phase adjustment control is known.

Theoretically, when the phase difference of the voltage between a certain generator bus is widened, the voltage of the bus located in the middle drops the most. Therefore, in order to recover the voltage of the bus, it is necessary to identify a generator whose phase angle is open from the reference power source and have a large internal phase difference angle, and to control the generator. If it is possible to identify in advance a generator whose internal phase difference angle opens due to a power line failure or the like, the electric control candidate generators can be limited.

Japanese Unexamined Patent Publication No. 2011-26583

In order to suppress the transient voltage drop phenomenon that occurs in the system after an accident occurs, if the number of generators is small within a limited range, the generator with the largest amount of bus voltage recovery with respect to the amount of power control is relatively selected. It can be decided as an electronic control target in a short time. However, when a large number of generators existing in a wide area are shaken due to a backbone system failure, it is difficult to detect the generator having the largest amount of bus voltage recovery with respect to the amount of power control in a short time.

An embodiment of the present invention has been made to solve the above-mentioned problems, and is an electric control device selection method and an electric control device selection program capable of suppressing a transient voltage drop after elimination of a failure in a power system. And its recording medium.

In order to achieve the above object, the electric controller selection method of the present embodiment is an electric controller selection method for determining a generator to be electronically controlled that suppresses a transient voltage drop that occurs after removing a failure of the power system. , A bus selection step for selecting a bus whose voltage transiently drops after the power system failure is eliminated, and a voltage stabilizing power source for identifying one or more electronic control candidate generators that cause the transient voltage drop of the bus. The control candidate identification step, the equivalent one-to-infinity bus system model creation step for creating an equivalent one-to-infinity bus system model based on the bus and the one or more electronic control candidate generators, and the equivalent one. In the machine-to-infinity bus system model, the voltage or voltage recovery amount of the bus when one or more electric control candidate generators are electrically controlled is calculated, and the voltage or the voltage recovery amount is preset. a voltage determination step stabilizing electrical control to determine the one or more generators that satisfy the criteria as electrical control subjects, was closed, the bus selection step, from the transient stability analysis simulation results for the power system, the power Select a bus whose bus voltage is lower than a predetermined threshold for a predetermined time from a plurality of bus lines in the system, and select the bus whose bus voltage becomes the minimum value after the failure is removed from the selection results. It is characterized by.

The present embodiment can also be grasped from the viewpoint of the program. Further, it can be regarded as a recording medium that can be read by a computer on which the program is recorded.

It is a figure which shows the structure of the electronic control machine selection method which concerns on this embodiment. It is a figure which shows the time change of each bus voltage and the internal phase difference angle of a generator by the transient stability analysis simulation of the target power system. It is a figure which shows the structure of the equivalent 1 machine vs. infinity bus system model creation step. It is a figure for demonstrating the calculation target range of the equivalent one-to-infinity bus system model. This is a model system that is a generalized representation of the system that is the calculation target range shown in FIG. This is an equivalent one-to-infinity bus system model that contracts the system that is the calculation target range. It is a figure which shows the structure of the electric control determination step for voltage stabilization. It is a figure which shows the structure of the voltage recovery amount calculation step. It is a figure which shows the definition of the generator machine input, the generator output, the angular velocity deviation and the internal phase difference angle for calculating the maximum value of the internal phase difference angle after electric control.

[1-1. Constitution]
Hereinafter, the method for selecting an electronic control device according to the present embodiment will be described with reference to FIGS. 1 to 9. The method for selecting an electronic control device according to the present embodiment can be realized by a single computer or a system including a plurality of computers connected to a network and a display device. In the electronic control device selection method according to the present embodiment, the program is stored in a recording medium such as an HDD or SSD, expanded appropriately in a RAM, and processed by a CPU, whereby each step described later can be performed. .. A system or device configured to realize this electronic control unit selection method can acquire information required at each step online. This electric control device selection method can be applied to, for example, a power system stabilizer.

The method for selecting an electric controller according to the present embodiment is a method for selecting a generator to be electronically controlled that suppresses a transient voltage drop that occurs after removing a failure in the power system. Generally, the electric control that shuts off the generator that destabilizes the power system from the system is performed to prevent the generator from stepping out. By performing electric control, it is possible to stabilize the power system. However, even when the electric control is performed, the voltage of the bus in the power system may decrease transiently.

This electric control device selection method is a method of additionally selecting a generator to be electronically controlled in order to suppress a transient voltage drop after performing electronic control to prevent step-out of the generator. .. In addition, after the failure of the power system is eliminated, the system may not become unstable and it may not be necessary to control the power system to prevent step-out of the generator. Even in this case, a transient voltage drop can occur due to the shaking of the generator in the power system. In this case, the method of selecting the generator to be electronically controlled in order to suppress the voltage drop is also the target of the electronically controlled selection method of the present embodiment.

The electric control of this embodiment is an electric control for recovering the voltage of the bus in the power system, and is distinguished from the electric control for preventing step-out of the generator. Therefore, in the following, the present embodiment is targeted. The electric power system to be used may be referred to as "voltage stabilizing electric power system". Unless otherwise specified, the term "electric control" refers to voltage stabilization.

FIG. 1 is a diagram showing a configuration of an electronic control device selection method according to the present embodiment. As shown in FIG. 1, the electronic control device selection method has the following steps (1) to (4).
(1) Bus selection step 1 for selecting a bus whose voltage drops transiently after removing a failure in the power system.
(2) Voltage stabilization electronic control candidate identification step 2 for identifying one or more electronic control candidate generators that cause a transient voltage drop of the bus selected in the bus selection step.
(3) Equivalent one machine to create an infinite bus system model based on the bus line selected in the bus bar selection step and one or more electric control candidate generators specified in the voltage stabilization electronic control candidate identification step. Step 3 for creating a generatrix system model for infinity.
(4) In the equivalent one-to-infinity bus system model, the voltage recovery amount of the bus when one or more electric control candidate generators are electrically controlled is calculated, and the voltage recovery amount satisfies a predetermined standard set in advance. Step 4 for determining the voltage stabilization electronic control, which determines one or more generators to be electronically controlled.

(1) Bus selection step In the bus selection step 1, a bus whose bus voltage is transiently reduced in the power system is selected from the transient stability analysis simulation results for the target power system. More specifically, in the bus selection step 1, from the transient stability analysis simulation results for the power system, the bus with the earliest time when the bus voltage reaches the minimum value after the failure is removed is selected from the plurality of bus lines of the power system. To do. In other words, the bus whose bus voltage becomes the minimum value first after the failure is eliminated is selected. As the transient stability analysis simulation result for the power system, those obtained by any power system stabilizer can be used.

FIG. 2 is a diagram showing the time change of each bus voltage and the internal phase difference angle of the generator by the transient stability analysis simulation of the target power system. FIG. 2 shows graphs A to C of voltage changes of a plurality of (three in this case) bus lines of the power system. As shown in FIG. 2, when the circuit breaker in the power system operates at the failure occurrence point tf, the bus voltage drops from the failure occurrence point tf to the failure elimination time ct. Then, when the circuit breaker in the power system is turned on at the failure elimination time ct and the circuit is reclosed, the bus voltage temporarily recovers, but the voltage drop phenomenon occurs transiently due to the shaking of the generator.

As shown in FIG. 2, in the bus bar selection step 1 of the present embodiment, among the busbars whose busbar voltage VT is lower than the voltage drop determination threshold value VL for a certain period of time TL or more, the busbar voltage first becomes the busbar voltage after the failure elimination time ct. Select the bus that is the minimum value. The threshold value VL is empirically determined from the result of performing the transient stability analysis simulation of the target system a plurality of times and the voltage value that is acceptable in operation. For example, the threshold VL can be 80% of the rating of the bus voltage. In FIG. 2, the time point at which the bus voltage reaches the minimum value earliest is defined as t2. In the example of FIG. 2, the generatrix to be the graph A is selected. As shown in FIG. 2, the voltage drop of the other bus is minimized after the fact, but these are not selected in this step 1.

In the bus selection step 1 of the present embodiment, the time TL at which the bus voltage falls below the threshold value VL is set to a predetermined time. This time is set, for example, to be shorter than the duration of the undervoltage in which the undervoltage relay provided in the power receiving equipment of the consumer operates. This is to suppress the transient voltage drop of the target bus before the undervoltage relay operates due to the transient voltage drop. The bus line selected in the main bus line selection step 1 may be referred to as a corresponding bus line.

(2) Voltage stabilization electronic control candidate identification step In the voltage stabilization electronic control candidate identification step 2, one or more electronic control candidate generators that cause a transient voltage drop of the bus selected in the bus selection step 1 are specified. .. Specifically, as shown in FIG. 2, at the time t2 when the target bus voltage reaches the minimum value earliest after the failure elimination time tc, the internal phase difference angle δT of the generator is preset electronic control candidate selection. It is selected as one or more generators 1 to n connected to the target bus having a threshold value of δL or more. The electronic control candidate selection threshold value δL is empirically determined by the result of performing the transient stability analysis simulation of the target system a plurality of times. For example, the threshold δL can be 90 °.

(3) Equivalent one-to-infinity bus system model creation step In the equivalent one-to-infinity bus system model creation step 3, the bus selected in the bus selection step 1 and the voltage stabilizing electronic control candidate identification step 2 are selected. Create an equivalent one-to-infinity busbar system model based on one or more electronically controlled candidate generators. As shown in FIG. 3, in this step 3, the calculation target range determination step 31 which is the calculation target of the equivalent one-to-infinity bus system model and the calculation target range determined in the step are reduced, and the equivalent one machine. It has a model creation step 32 for creating an anti-infinity bus system model.

(3-1) Calculation target range determination step This step 31 is connected to the corresponding bus and is connected to the corresponding bus of the generator group including the generator specified in the voltage stabilization reactance candidate identification step 2. Equivalent synthetic reactance is calculated for each, and the calculation target range is determined. The calculation target range is the system on the generator group side that minimizes the equivalent synthetic reactance from the corresponding bus, and is the range from the corresponding bus to the generator group that minimizes the equivalent synthetic reactance. Hereinafter, a specific description will be given with reference to FIG.

FIG. 4 is a diagram for explaining the calculation target range of the equivalent one-machine vs. infinity bus system model. In FIG. 4, a plurality of bus bars shown by thick lines are shown, but the corresponding bus bar is 275A1, and the internal phase difference angle is equal to or higher than the threshold value δL at the time t2 when the bus bar voltage becomes the minimum value earliest after the failure is eliminated. When the generators are A1G to A4G and B1G to B4G, there are two corresponding generator groups. Therefore, in this step, the equivalent reactance 2X from the bus 275A1 to the generators A1G to A4G and the equivalent reactance 8X from the bus 275A1 to the generators B1G to B4G are calculated, respectively. Then, the calculated equivalent synthetic reactances are compared, and the systems from the corresponding bus 275A1 to the generators A1G to A4G having the minimum equivalent synthetic reactance are set as the calculation targets of the equivalent one-infinity bus system model. Note that X is a reactance value (pu) per unit length of the transmission line.

Although a plurality of electric control candidate generators are specified by the voltage stabilization electric control candidate step 2 in this way, it is the voltage stabilization electric control candidate identification that determines the calculation target range so as to limit the range. When the electronic control candidate generators identified in step 2 are distributed over a wide area, the voltage of the corresponding bus that is finally calculated in the calculation using the equivalent one-to-infinity bus system model that combines those generators into one equivalent. This is because the error in the amount of recovery becomes large. Systems including other generator groups B1G to B4G beyond the corresponding bus 275A1 are out of the calculation range, sandwiching the generator common bus S to which the generators A1G to A4G and the generators B1G to B4G are commonly connected. ..

As described above, the generator group may include one or more generators specified as voltage stabilization electronic control candidates. As a method of determining which range of generators should be one generator group, for example, as described in FIG. 4, the generators A1G to A4G provided on the bus connected to the corresponding bus 275A1 are combined into one generator group. Then, the generators B1G to B4G beyond the corresponding bus line when viewed from the other generator groups are regarded as one generator group.

(3-2) Model Creation Step FIG. 5 is a model system that is a generalized representation of the system that is the calculation target range shown in FIG. FIG. 6 is an equivalent one-to-infinity bus system model in which the system to be calculated is reduced. The explanation of each parameter shown in FIG. 5 is as follows.

E: Infinite bus voltage (pu) at the first minimum point t2 when the transient voltage drops. It is obtained from the transient stability analysis simulation result.
X0: Equivalent reactance beyond the corresponding bus (pu).
V : Corresponding bus voltage (pu) at the first minimum time point t2 of the transient voltage drop. It is obtained from the transient stability analysis simulation result.
Xg1 to Xgn: Combined reactance (pu) of each of the generators 1 to n as seen from the generator high-voltage side bus of the generator candidate generators 1 to n. Obtained by calculation from known equipment data.
Eg1 to Egn: It is assumed that the internal voltage (pu) of the electronically controlled candidate generators 1 to n at the first minimum time point t2 of the transient voltage drop is 1.0.
δg1 to δgn: Internal phase difference angle (rad) of the electronic control candidate generators 1 to n at the first minimum time point t2 of the transient voltage drop. It is obtained from the transient stability analysis simulation result.

In this step 32, the determined calculation target range is reduced to the equivalent one-machine vs. infinity bus system model. Specifically, in this step 32, in the system to be calculated, one or more units having the minimum equivalent reactance in the path from the corresponding bus to the generator group having the internal phase difference angle of the predetermined threshold δL or more. Create an equivalent one-to-infinity bus system model from the equivalent one-gene generator reactance and the equivalent back reactance from the corresponding bus to the infinity bus.

As the reduction method, a conventional method can be used, and in the present embodiment, the method shown below is used. In addition, for example, the short-circuit capacitance method, short-circuit current method, dual load method, etc. are calculated mathematically according to the system to be reduced, and the power flow and voltage at the interconnection point between the original system model and the accident occurrence. It is also possible to use a method of combining the characteristics such as, and a method of combining the dynamic characteristics after the accident with the original system model in addition to the characteristics at the time of the accident.

In this step 32, first, before the reduction, the parameters required for the reduction are obtained. Specifically, the parameters to be obtained are as follows. Various information such as transient stability analysis simulation results or known equipment data required for calculation of each parameter is acquired online.

２．過渡電圧低下最初極小値ｔ２の等価一機発電機の内部相差角δ（ｒａｄ）
δは、過渡安定度解析シミュレーション結果及び既知の設備データから、式（２）より算出できる。

ＭＶＡ１〜ＭＶＡｎ：電制候補発電機１〜ｎの発電機容量（ＭＶＡ）。既知の設備データから得られる。
３．演算対象範囲の各発電機リアクタンスＸｇ１〜Ｘｇｎの合成リアクタンスＸｇＧ（ｐ.ｕ．）
ＸｇＧは、既知の設備データから、式（３）より算出できる。

４．該当母線から見た発電機側共通母線までの送電線路合成リアクタンスＸＬ（ｐ.ｕ．）
ＸＬは、既知の設備データから計算によって得られる。計算方法は、公知の方法を用いることができる。
５．該当母線から見た等価一機発電機側の合成リアクタンスＸＧ（ｐ.ｕ．）
ＸＧは、式（４）より算出できる。

６．該当母線の電圧Ｖ（ｐ.ｕ．）
Ｖは、式（５）より算出でき、その大きさは、式（６）により算出できる。なお、本明細書の文中のＶは、以下の各式中のＶ上付きドットと同義である。

７．該当母線以遠の等価リアクタンスＸ０（ｐ.ｕ．）
Ｘ０は、過渡安定度解析シミュレーション結果から、式（７）より算出できる。

1. 1. Transient voltage drop Equivalent single generator with initial minimum value t2 Internal voltage EG (pu)
The EG can be calculated from the equation (1) from the transient stability analysis simulation result.

2. Transient voltage drop The internal phase difference angle δ (rad) of the equivalent single generator with the initial minimum value t2
δ can be calculated from Eq. (2) from the transient stability analysis simulation results and known equipment data.

MVA1 to MVAn: Generator capacity (MVA) of electronically controlled candidate generators 1 to n. Obtained from known equipment data.
3. 3. Combined reactance XgG (p.u.) of each generator reactance Xg1 to Xgn in the calculation target range
XgG can be calculated from the known equipment data by the equation (3).

4. Transmission line combined reactance XL (pu) from the relevant bus to the common bus on the generator side
XL is calculated from known equipment data. A known method can be used as the calculation method.
5. Synthetic reactance XG (p.u.) on the equivalent single generator side as seen from the relevant bus
XG can be calculated from the equation (4).

6. Voltage V of the corresponding bus (p.u.)
V can be calculated by the formula (5), and its magnitude can be calculated by the formula (6). Note that V in the text of this specification is synonymous with V superscript dots in each of the following equations.

7. Equivalent reactance X0 (p.u.) beyond the relevant bus
X0 can be calculated from the equation (7) from the transient stability analysis simulation result.

The determined calculation target range is reduced by using the parameters 1 to 7 above. The equation (7) is derived as follows.

そして、式（８）を変形して式（９）を得る。

First, α = XG / (X0 + XG) is set, and both sides of the equation (5) are squared to transform into the equation (8) which is a quadratic equation of α.

Then, the equation (8) is modified to obtain the equation (9).

Equation (10) can be obtained from equation (9).

Equation (11) is obtained from α = XG / (X0 + XG).

Equation (12) is obtained from equations (10) and (11).

式（１３）は、電制によりＸＧが大きくなるとαが大きくなることを示している。従って、電制により電圧回復を見込めるαは式（７）で表現される。 Eq. (13) is obtained by partially differentiating α with respect to XG.

Equation (13) shows that α increases as XG increases due to electronic control. Therefore, α, which is expected to recover the voltage by electronic control, is expressed by the equation (7).

(4) Voltage stabilization electronic control determination step In the voltage stabilization electronic control determination step 4, the voltage of the corresponding bus when one or more electric control candidate generators are electronically controlled in the equivalent one-to-infinity bus system model. The amount of recovery is calculated, and one or more generators whose voltage recovery amount satisfies a predetermined standard set in advance are determined as the target of electronic control.

Specifically, as shown in FIG. 7, this step 4 is subject to electronic control from one or more generators constituting the created equivalent one-to-infinity bus system model equivalent one-gene generator. A combination creation step 41 for creating a combination of generators, a voltage recovery amount calculation step 42 for calculating the voltage recovery amount of the corresponding bus by electronic control for each combination, and each number of generators subject to electronic control in the combination. , The maximum combination specifying step 43 for specifying the combination with the maximum voltage recovery amount, and the combination selection step 44 for selecting the combination with the minimum number of generators subject to electronic control from the combinations specified in the maximum combination specifying step. Has.

(4-1) Combination creation step In this step 41, the combination of the generators subject to electronic control is selected from one or more generators constituting the equivalent generator of the created equivalent one-to-infinity bus system model. To create. For example, to explain with reference to FIG. 5, since the generator group to be one equivalent unit consists of four generators A1G to A4G, there is a case where one of them is electrically controlled (= ₄ C ₁ ). As you can see, there are 6 (= ₄ C ₂ ) when 2 units are electrically controlled, 4 (= ₄ C ₃ ) when 3 units are electrically controlled, and 1 (= ₄ C _{4) when 4 units are electrically controlled.} ) As shown in the street, create a combination of electric control target generators for each number of electric control target generators.

(4-2) Voltage recovery amount calculation step In this step 42, the voltage recovery amount of the corresponding bus by the electric control is calculated for each combination of the generators subject to the electronic control. The voltage recovery amount is the difference between the corresponding bus voltage after the electric control and the corresponding bus voltage before the electric control. In this step 42, the transient stability analysis simulation, which is a dynamic analysis, is not performed one by one, but is simplified by a static analysis of only algebraic calculation, as will be described later. As shown in FIG. 8, this step 42 includes a generator output calculation step 421, an internal phase difference angle maximum value calculation step 422 after electronic control, and a voltage recovery amount calculation step 433 of the corresponding bus by electronic control. ..

(1) Generator output calculation step In this step 421, from the created equivalent one-to-infinity bus system model, the generator output Pf during failure in the equivalent one generator, the generator output P1 after failure removal, and The generator output P2 after reclosing is calculated. Therefore, as shown in FIG. 9, changes in the active power P, the angular velocity deviation Δω, and the internal phase difference angle δT of the equivalent single generator generator after the failure occurs are defined. A description of each symbol shown in FIG. 9 is shown below. The time when the failure occurs is t = 0. Further, in the following, the equivalent single generator is simply referred to as a generator.

tk: Failure removal time point (s)
t1: At the time of reclosing (s)
t2: Transient voltage drop First minimum time point (s)
ts: At the time of electronic control (s)
t3: Time point when δT becomes maximum after electronic control (s)

P0: Generator machine input before electronic control (pu)
Pf: Generator output during failure (0 ≦ t <tk) (p.u.)
P1: Generator output after failure removal (output reduced state) (tk≤t <t1) (p.u.)
P2: Generator output after reclosing (output increased state) (t ≧ t1) (pu)
P0': Generator machine input after electronic control (pu)
ΔPs: Electrostatic amount (pu)

Δω: Angular velocity deviation during failure (0 ≦ t <tk) (p.u.)
Δω1: Angular velocity deviation after failure removal (without electrical control: ct ≤ t <t1, with electrical control: tk ≤ t <ts) (pu)
Δω2: Angular velocity anomaly deviation (t ≧ t1) (pu) after reclosing without electronic control
Δω1s: Angular velocity deviation after electronic control (tk ≦ t <t1) (pu)
Δωs: Angular velocity anomaly deviation (t ≧ t1) (pu) after reclosing with electronic control

Δδ: Amount of change in maximum internal phase difference angle (rad) due to electronic control
δc: Internal phase difference angle during failure (0 ≦ t <tk) (rad)
δ1: Internal phase difference angle after failure removal (without electrical control: ct ≤ t <t1, with electrical control: tk ≤ t <ts) (rad)
δ2: Internal phase difference angle (t ≧ t1) (rad) without electronic control and after reclosing
δ1s: Internal phase difference angle after electronic control (ts ≦ t <t1) (rad)
δs: Internal phase difference angle (t ≧ t1) (rad) with electronic control and after reclosing

At the time point ct, when the active power of the equivalent single generator recovers from Pf (Pf <P1) to P1 (P1 <P0) after the failure is eliminated, the angular velocity deviation Δω has a positive slope before the time point ct and is Δωc (t). After the time point tk, it changes as Δω1 (t) with a relatively gentle slope.
At time point t1, when the active power of the equivalent single generator recovers from P1 (P1 <P0) to P2 (P2> P0) after reclosing, the angular velocity deviation Δω has a negative slope after time point t1 (t). ) Changes.
On the other hand, assuming that the internal phase difference angle δ of the equivalent single generator generator is the peak value δ2 (t2) at the time of the first minimum transient voltage drop t2, Δω2 (t2) = 0.

Next, assuming that the electric control of the electric control amount ΔPs is performed at the time point ts, the generator machine input P0 changes to P0'(= P0-ΔPs).

Here, paying attention to the time before and after the time point t3 at which the internal phase difference angle reaches the peak value after the electric control and the time point t1 at the time of reclosing, the case where t3 ≧ t1 and the case where t3 <t1 are obtained are classified. When the electric control amount ΔPs is large, the deceleration of the generator is fast, so that the peak of the internal phase difference angle comes before the time of reclosing. On the contrary, when the electric control amount ΔPs is small, the deceleration of the generator is slow, so that the peak of the internal phase difference angle is after the time of reclosing, and the equation to be solved changes before and after the reclosing.

As shown in FIG. 9A, when t3 ≧ t1, the angular velocity deviation after the time point ts (ts <t1) changes as Δω1s (t) with a gentler inclination than Δω1 (t), and after the time point t1. Changes with a negative slope larger than Δω2 (t) as Δωs (t), and Δωs (t3) = 0 at the time point t3. In this case, the peak value of the internal phase difference angle of the equivalent single generator after the electric control is δs (t3), and the amount of change Δδ of the maximum value of the internal phase difference angle due to the electronic control is Δδ = δs (t3) −δ2 (t2). ).

As shown in FIG. 9B, when t3 <t1, the angular velocity deviation after the time point ts (ts <t1) changes with a large negative slope as Δω1s (t), and is before the time point t1. At the time point t3, Δω1s (t3) = 0. In this case, the peak value of the internal phase difference angle of the equivalent single generator after the electric control is δ1s (t3), and the amount of change Δδ of the maximum value of the internal phase difference angle due to the electronic control is Δδ = δ1s (t3) −δ2 (t2). ).

In FIG. 9, the angular velocity deviations Δωc (t), Δω1 (t), Δω2 (t) and the internal phase difference angles δc (t), δ1 (t), and δ2 (t) before electronic control are expressed by the following equations, respectively. To.

The parameters of equations (14) to (21) are as follows.
M: Inertia constant (s) of equivalent single generator (weighted average value based on generator rated capacity)
ω0: Basic angular velocity (rad / s). Obtained from known equipment data.
M1 to Mn: Inertial constants (s) of the electronically controlled candidate generators 1 to n. Obtained from known equipment data.
MVA1 to MVAn: Generator capacity (MVA) of electronically controlled candidate generators 1 to n. Obtained from known equipment data.
δ0: Internal phase difference angle before failure of equivalent single generator (initial value, weighted average value based on generator rated capacity) (rad)

The following parameters can be obtained from the conditions and results of the transient stability analysis simulation.
tk: Failure removal time point (s)
δc (tk): Internal phase difference angle (rad) at time point ct
t2: Transient voltage drop First minimum value time point δ2 (t2): Internal phase difference angle (rad) at time point t2
δ01 to δ0n: Internal phase difference angle (rad) before failure of the electronic control candidate generators 1 to n

（２２）式を変形して（２３）式を得る。

In equations (14) to (16), P0-Pf = ΔPf, P0-P1 = ΔP1, P0-P2 = ΔP2, and when t = t2, considering that Δω2 (t2) = 0, the following The relational expression of the expression is derived.

Equation (22) is modified to obtain equation (23).

（２４）式に（２３）式を代入すると式（２５）を得る。

（２５）式を変形して（２６）式を得る。

From equations (14) to (19), δ2 (t2) is expressed by equation (24).

Substituting equation (23) into equation (24) gives equation (25).

Equation (25) is modified to obtain equation (26).

Since ΔPf is known from the transient stability analysis simulation result in the equation (17), it can be calculated from the equation (27).

ΔPf can be obtained by the equation (27), it can be substituted into the equation (26) to obtain ΔP1, and further, ΔPf and ΔP1 can be substituted into the equation (23) to obtain ΔP2. Therefore, Pf, P1 and P2 can be calculated from the equations (28) to (30), respectively.

(2) Step for calculating the maximum internal phase difference angle after electronic control In this step, the maximum value of the internal phase difference angle of the equivalent single-unit generator after electronic control is calculated. The angular velocity deviation Δω1 (ts) and the internal phase difference angle δ1 (ts) at the time point ts when the electric control is applied in FIG. 8 are represented by the equations (31) and (32), respectively. Further, the angular velocity deviations Δω1s (t) and Δωs (t) and the internal phase difference angles δ1s (t) and δs (t) are represented by the equations (33) to (36), respectively.

式（３７）の各パラメータは以下の通りである。
Ｍ１〜Ｍｋ：電制候補発電機１〜ｎの内、電制されていない発電機１〜ｋの慣性定数（ｓ）
ＭＶＡ１〜ＭＶＡｋ：電制候補発電機１〜ｎの内、電制されていない発電機１〜ｋの発電機容量（ＭＶＡ） In equations (31) to (36), M'represents the equivalent inertial constant after electronic control and is represented by equation (37).

Each parameter of equation (37) is as follows.
M1 to Mk: Of the electric control candidate generators 1 to n, the inertial constants (s) of the non-electrically controlled generators 1 to k.
MVA1 to MVAk: Generator capacity (MVA) of generators 1 to k that are not electrically controlled among the generators 1 to n that are candidates for electronic control.

ＸＧＳは、電制後の等価一機発電機側の合成リアクタンスであり、電制後の系統状態に基づき、式（３）及び式（４）から算出できる。式（３８）及び式（３９）に示すＰ１’及びＰ２’は、電制後の等価一機発電機の有効電力を、電制前後の等価一機発電機側合成リアクタンスの変化を加味したものである。すなわち、電制によって電制対象の発電機が遮断されるため、本来的には、演算対象範囲の系統モデルを変更する必要がある。しかし、電制後の等価一機対無限大母線系統モデルを再作成しても良いが、式（３８）及び式（３９）の右辺の第２因子が補正係数となり、電制前の等価一機体無限大母線系統モデルを使用してその後の母線電圧などの計算を実行しても精度の高い結果を得られる。 Further, P1'and P2'are the generator outputs after the electric control, and can be calculated from the equations (38) and (39), respectively.

XGS is a synthetic reactance on the equivalent single generator side after the electric control, and can be calculated from the equations (3) and (4) based on the system state after the electric control. P1'and P2'shown in equations (38) and (39) are the active power of the equivalent single generator after the electric control, taking into account the change in the combined reactance on the equivalent single generator side before and after the electronic control. Is. That is, since the generator subject to electronic control is cut off by electronic control, it is essentially necessary to change the system model of the calculation target range. However, although the equivalent one-to-infinity bus system model after electronic control may be recreated, the second factor on the right side of equations (38) and (39) becomes the correction coefficient, and the equivalent one before electronic control. Highly accurate results can be obtained even if the subsequent calculations such as the bus voltage are performed using the infinity bus system model of the aircraft.

式（４０）において、Ｐ０’は、電制後の等価一機発電機の発電機機械入力であり、電制候補発電機１〜ｎのうち、電制されていない発電機１〜kの発電機機械入力を合計することで算出できる。 Gm is a coefficient for converting the angular velocity deviation of the equivalent single-unit generator immediately before the electric control into the angular velocity deviation of the equivalent single-unit generator after the electric control, and can be calculated from the equation (40). This Gm is a correction factor.

In the formula (40), P0'is the generator machine input of the equivalent single generator after the electric control, and among the electric control candidate generators 1 to n, the power generation of the uncontrolled generators 1 to k is generated. It can be calculated by summing the machine-machine inputs.

ΔPs can be calculated from the equation (41).

When t3 ≧ t1, after the electric control, ωs (t3) = 0 at t = t3, so t3 can be calculated from the formula (34) as shown in the formula (41).

From t3 obtained from the equation (42), δs (t3) can be calculated from the equation (36) as shown in the equation (43).

When t3 <t1, after the electric control, ω1s (t3) = 0 at t = t3, so t3 can be calculated as shown in equations (33) to (44).

From t3 obtained from equation (44), δ1s (t3) can be calculated from equation (35) as shown in equation (45).

From the above, the maximum internal phase difference angle δsmax after electronic control is δs (t3) represented by the formula (43) when t3 ≧ t1, and δ1s represented by the formula (45) when t3 <t1. Each can be calculated as (t3).

(3) Step for calculating the voltage recovery amount of the corresponding bus As described above, when the generator is electrically controlled, the combined reactance on the equivalent single generator side as seen from the corresponding bus changes from XG to XGS. This XGS can be calculated from the equations (3) and (4) from the system configuration after the electronic control. From XGS and Derutasmax, the size of the corresponding bus voltage becomes the minimum after electronically controlled | V smin | is obtained by equation (46).

On the other hand, the minimum value | V min | of the magnitude of the corresponding bus voltage in the case of no electric control can be obtained from the conditions and results of the transient stability analysis simulation. From the equation (46) and the minimum value | V min | obtained from the transient stability analysis simulation result, the voltage recovery amount ΔV can be calculated from the equation (47).

(4-4) Combination Selection Step In this step 44, the combination that minimizes the number of generators subject to electronic control is selected from the combinations specified in the maximum combination identification step 43. Specifically, among the combinations specified in the maximum combination specifying step 43, a combination having a voltage recovery amount higher than a predetermined voltage improvement amount and a minimum number of generators subject to electronic control is selected. When the calculated voltage recovery amount is higher than the predetermined voltage improvement amount, the voltage recovery amount satisfies the preset predetermined voltage improvement amount.

[1-2. Action / effect]
(1) The electric control device selection method of the present embodiment is an electric control device selection method for determining a generator to be electronically controlled that suppresses a transient voltage drop that occurs after removal of a power system failure, and is a power system failure. A bus selection step 1 for selecting a bus whose voltage drops transiently after removal, and a voltage stabilization electronic control candidate identification step 2 for identifying one or more electric control candidate generators that cause a transient voltage drop of the corresponding bus. And, the equivalent one-to-infinity bus system model creation step 3 to create an equivalent one-to-infinity bus system model based on the corresponding bus and one or more electronic control candidate generators, and the equivalent one-to-infinity bus system model In the grid model, the voltage recovery amount of the corresponding bus when one or more electric control candidate generators are electronically controlled is calculated, and one or more generators whose voltage recovery amount satisfies a predetermined standard set in advance are electricized. The voltage stabilizing electronic control determination step 4 for determining the control target is provided.

As a result, even if a failure occurs in a backbone system in which a generator exists over a wide area and a transient voltage drop occurs after the failure is removed, the generator to be electronically controlled to suppress the voltage drop is specified. can do. For example, when the electronic control device selection method of the present embodiment is applied to a power system stabilizer, an appropriate electronic control target for a assumed accident is calculated and selected based on online information in the time control of real-time control. can do.

(2) Busbar selection In step 1, from the results of the transient stability analysis simulation for the power system, the busbar with the earliest time when the busbar voltage reaches the minimum value after the failure is removed is selected from among the plurality of busbars in the power system. ..

As a result, it is possible to prevent a voltage drop of another bus that may inevitably occur due to a voltage drop of the corresponding bus. That is, it is considered that there is a generator that transiently causes the voltage drop on the bus where the bus voltage becomes the minimum value earliest after the failure is removed. It is possible to prevent the influence of the voltage drop of the bus from spreading to other buses. Therefore, by selecting the bus whose bus voltage is the earliest and the minimum value as the target bus, it is possible to prevent the voltage drop of the other bus that may inevitably occur due to the voltage drop of the corresponding bus.

(3) In the bus selection step, a bus whose bus voltage is lower than a predetermined threshold for a predetermined time is selected from a plurality of bus lines of the power system from the transient stability analysis simulation result for the power system.

As a result, the power quality of the power system can be ensured. That is, in a situation where power is supplied from the power system to the consumer via the power receiving equipment, the power receiving equipment may be provided with an undervoltage relay. In this case, if the bus voltage drops below a predetermined threshold for a predetermined time, the relay may operate and power may not be supplied. For example, of the set undervoltage and undervoltage of the relay. By selecting a bus whose bus voltage is lower than a predetermined threshold for a predetermined time so as not to have a duration, it is possible to prevent the operation of the relay and enable stable power supply.

(4) In step 2 of specifying the voltage stabilization electronic control candidate, one or more generators having an internal phase difference angle equal to or higher than a preset threshold value are selected at the time when the bus voltage reaches the minimum value earliest after the failure is removed. I did. This makes it possible to identify a generator that can prevent a transient drop in the bus voltage.

(5) Equivalent one machine vs. infinity bus system model creation In step 3, the system with the minimum equivalent synthetic reactance in the path from the corresponding bus line to the generator group whose internal phase difference angle is equal to or more than a predetermined threshold value is equivalent to one. The machine-to-infinity system model has a calculation target range determination step 31 to be calculated. As a result, a group of generators that are electrically close to the bus that reaches the minimum value earliest after the failure is eliminated can be a candidate for voltage stabilization, so the contribution to suppressing the transient voltage drop can be increased. Can be done.

(6) In the step of creating an equivalent one-to-infinity bus system model, the equivalent synthetic reactance is generated in the path from the bus to the generator group whose internal phase difference angle is equal to or higher than a predetermined threshold in the system to be calculated. Create an equivalent one-to-infinity bus system model from the equivalent one-gene generator reactance and the equivalent back reactance from the bus to the infinity bus, using one or more of the smallest generators as the equivalent one-gene generator. Have a model creation step to do.

As a result, in order to make a simple model of equivalent one machine vs. infinity bus system model, it is possible to select a generator to be electronically controlled by a simple calculation.

(7) In step 4 of determining the electronic control for voltage stabilization, a combination of generators subject to electronic control is selected from one or more generators constituting the equivalent single generator of the equivalent one-to-infinity bus system model. The combination creation step 41 to be created, the voltage recovery amount calculation step 42 for calculating the voltage recovery amount of the corresponding bus by electronic control for each combination, and the maximum voltage recovery amount for each number of generators subject to electronic control in the combination. From the combination specified in the maximum combination specifying step 43 and the maximum combination specifying step 43, the voltage recovery amount is higher than the preset predetermined voltage improvement amount, and the number of generators subject to electronic control To have a combination selection step 44, which selects the combination that minimizes.

This makes it possible to efficiently determine the combination of the generators subject to electronic control that maximizes the amount of voltage recovery. In addition, when the transient stability analysis simulation that electrically controls the determined generators subject to electronic control is performed, even if the amount of voltage recovery does not satisfy the predetermined amount of voltage improvement, the number of generators subject to electronic control in the combination. Since the combination with the maximum voltage recovery amount is specified for each case, there is an advantage that it is not necessary to redo the determination of the generator to be controlled by the electric control.

(8) In step 4 of determining the electronic control for voltage stabilization, the active power of the equivalent single generator after the electronic control is calculated by taking into account the change in the combined reactance on the equivalent single generator side before and after the electronic control. .. As a result, the active power of the equivalent single generator after the electric control is corrected, so there is no need to modify the equivalent single unit vs. infinity bus system model before and after the electronic control, and the calculation result of the voltage recovery amount with high accuracy can be obtained. A generator that can be obtained and, as a result, can effectively suppress a decrease in transient voltage can be determined as an electronic control target.

(9) In step 4 of determining the electronic control for voltage stabilization, the angular velocity deviation of the equivalent single generator after the electronic control is calculated by taking into account the change in the active power before the failure and the inertial constant before and after the electronic control. As a result, the angular velocity deviation of the equivalent single generator after the electric control is corrected, so that a highly accurate calculation result of the voltage recovery amount can be obtained, and as a result, the transient voltage drop can be effectively suppressed. The generator can be determined as the target of electronic control.

[2. Other embodiments]
Although a plurality of embodiments according to the present invention have been described herein, these embodiments are presented as examples and are not intended to limit the scope of the invention. The above-described embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

As another embodiment, in the above embodiment, the voltage recovery amount is calculated in the voltage stabilization electronic control determination step 4, but the voltage of the bus may be calculated. That is, in the voltage stabilization electronic control determination step 4, in the equivalent one-to-infinity bus system model, the voltage of the bus when one or more electric control candidate generators are electrically controlled is calculated, and the voltage is set in advance. One or more generators that satisfy the predetermined criteria may be determined as the target of electronic control. In addition, "the voltage satisfies a preset predetermined standard" means that the calculated bus voltage is higher than the preset voltage value. In this case, the voltage recovery amount calculation step 42 is a calculation step for calculating the voltage of the bus after electronic control for each combination created in the combination creation step 41. Further, the maximum combination specifying step 43 specifies the combination having the maximum calculated voltage for each number of generators subject to electronic control in the combination, and the combination selection step 44 specifies the combination specified in the maximum combination specifying step. Select a combination that has a voltage higher than a predetermined standard set in advance and that minimizes the number of generators subject to electronic control.

As another embodiment, in the above embodiment, the voltage recovery amount step 42 is executed for all the combinations of the electric control target generators, but the voltage recovery amount step 42 is performed in order from the combination with the smallest number of the electronic control target generators. Is executed, the calculation is terminated when the predetermined voltage improvement amount is exceeded, and the combination of the number of units after that may not be executed. This is to reduce the amount of calculation and select the generator subject to electronic control in a shorter time.

Moreover, the above-described embodiment can also be grasped from the viewpoint of the program. Further, it can be regarded as a recording medium that can be read by a computer on which the program is recorded. Further, the power system stabilizer to which the above embodiment is applied is also included in other embodiments.

Claims (9)

It is an electric control device selection method that determines the generator to be electronically controlled to suppress the transient voltage drop that occurs after removing the failure of the power system.
A bus selection step of selecting a bus whose voltage drops transiently after the power system failure is eliminated, and a bus selection step.
The voltage stabilization electronic control candidate identification step for identifying one or more electronic control candidate generators that cause the transient voltage drop of the bus, and
Equivalent one-to-infinity bus system model creation step to create an equivalent one-to-infinity bus system model based on the bus and the one or more electronic control candidate generators, and
In the equivalent one-to-infinity bus system model, the voltage or voltage recovery amount of the bus when one or more electric control candidate generators are electrically controlled is calculated, and the voltage or the voltage recovery amount is preset. A voltage stabilization electronic control determination step that determines one or more generators that satisfy the specified criteria as electronic control targets, and
Have,
In the bus selection step, a bus whose bus voltage is lower than a predetermined threshold for a predetermined time is selected from the plurality of bus lines of the power system from the transient stability analysis simulation result for the power system, and the bus is selected from the selection results. A method for selecting an electric control device, characterized in that the bus having the earliest time when the bus voltage reaches the minimum value after the failure is removed is selected. In the voltage stabilization electronic control candidate identification step, selecting one or more generators having an internal phase difference angle equal to or higher than a preset threshold value at the time when the bus voltage reaches the minimum value earliest after the failure is removed.
The method for selecting an electronic control device according to claim 1. In the equivalent pair-infinity bus system model creation step, the system having the minimum equivalent synthetic reactance in the path from the bus to the generator group whose internal phase difference angle is equal to or higher than a predetermined threshold value is selected as the equivalent pair. Having a calculation target range determination step to be calculated in the infinity bus system model,
The method for selecting an electronic control device according to claim 1 or 2. In the equivalent one-to-infinity bus system model creation step, the equivalent synthesis reactor is minimized in the path from the bus to the generator group whose internal phase difference angle is equal to or higher than a predetermined threshold in the system to be calculated. One or more generators are regarded as equivalent one generators, and the equivalent one generator reactors are calculated from the equivalent synthetic reactors of the equivalent one generators and the reactors obtained from known equipment data, and the equivalent one generator generators are generated. Having a model creation step to create an equivalent one-to-infinity bus system model from the machine reactor and the equivalent back reactor from the bus to the infinity bus.
3. The method for selecting an electronic control device according to claim 3. The voltage stabilization electronic control determination step is
A combination creation step of creating a combination of generators subject to electronic control from one or more generators constituting the equivalent generator of the equivalent one-to-infinity bus system model.
For each of the combinations, a calculation step of calculating the voltage of the bus after electronic control or the amount of voltage recovery of the bus by electronic control, and
For each number of generators subject to electronic control in the combination, the maximum combination specifying step for specifying the combination with the maximum calculated voltage or voltage recovery amount, and
From the combinations specified in the maximum combination specifying step, a combination selection that selects the combination that has a voltage or voltage recovery amount higher than a preset reference value and that minimizes the number of generators subject to electronic control. Steps and
The method for selecting an electronic control machine according to claim 4 , wherein the electronic control machine is selected. The voltage stabilization electronic control determination step is to calculate the active power of the equivalent single generator after the electronic control, taking into account the changes in the reactance of the equivalent single generator before and after the electronic control.
The method for selecting an electronic control device according to claim 4 or 5. In the voltage stabilization electronic control determination step, the angular velocity deviation of the equivalent single generator after the electric control is calculated by taking into account the change in the active power before the failure and the inertial constant before and after the electronic control.
The method for selecting an electronic control device according to any one of claims 4 to 6, wherein the electronic control device is selected. It is an electric control device selection program that determines the generator to be electronically controlled to suppress the transient voltage drop that occurs after removing the failure of the power system.
On the computer
Busbar selection processing to identify the busbar whose voltage drops transiently after removing the failure of the power system,
Voltage stabilization electronic control candidate identification processing that identifies one or more electronic control candidate generators that cause the transient voltage drop of the bus, and
Equivalent one-to-infinity bus system model creation process to create an equivalent one-to-infinity bus system model based on the bus and the one or more electronic control candidate generators,
In the equivalent one-to-infinity bus system model, the voltage when one or more electric control candidate generators are electrically controlled or the voltage recovery amount of the bus is calculated, and the voltage or the voltage recovery amount is preset. Voltage stabilization electronic control determination processing that determines one or more generators that satisfy the specified criteria as electronic control targets, and
To execute,
In the bus selection process, the computer is made to select a bus whose bus voltage is lower than a predetermined threshold for a predetermined time from among a plurality of bus lines of the power system from the transient stability analysis simulation result for the power system, and the selection result is obtained. among from the plurality of bus bars of the power system during the electrically controlled device selection program, characterized in that when the bus voltage is the minimum value after said fault removal to select the earliest bus. A recording medium characterized in that the electronic control device selection program according to claim 8 is readablely recorded by a computer.

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