JP7361646B2 - Power flow calculation device and power flow calculation program - Google Patents

Description

The present disclosure relates to a power flow calculation device and a power flow calculation program that calculate power flow in a power system.

Power flow calculation is a method for analyzing the state of power systems. In the power flow calculation, the voltage distribution and current distribution in the power system are calculated based on the power supplied to the power system and the power flowing from the power system to the load. Power flow calculations are used, for example, to monitor power systems, control power systems, and plan equipment for power systems.

Power flow calculations generally involve repeated calculations in which calculations are repeated until convergence, and there is a problem in that power flow calculations do not converge depending on the conditions of the power system, making it impossible to obtain voltage distribution and current distribution. For example, Patent Document 1 discloses a technique for converging the power flow calculation by changing the initial value of any one of voltage, current, or power flow and performing the calculation again when the power flow calculation diverges. ing.

JP2019-129644A

On the other hand, whether or not the power flow calculation diverges depends on what value is set to the initial value of the tap position of the SVR (Step Voltage Regulator), which automatically controls the voltage of the power system. do. For example, if the tap position of the SVR in the power flow calculation is significantly different from the tap position in actual operation, the power flow calculation will not converge. However, in general, the initial value of the tap position is set to a position where voltage control is not performed, that is, a transparent position, so that the power flow calculation may diverge depending on the input data for the power flow calculation. In the technology described in Patent Document 1, when a divergence occurs in the power flow calculation, the initial value of any one of the voltage, current, or power flow is changed and the power flow calculation is performed again. Divergence cannot be prevented, and the initial value of the tap position is not adjusted even in the second tidal flow calculation, so there is a problem that divergence may occur even in the second tidal flow calculation.

The present disclosure has been made in view of the above, and an object of the present disclosure is to obtain a power flow calculation device that can suppress divergence in power flow calculation.

In order to solve the above-mentioned problems and achieve the objectives, a power flow calculation device according to the present disclosure uses input data including equipment information regarding equipment in the power system and load power generation amount information indicating the load amount and power generation amount in the power system. and a power flow calculation unit that performs power flow calculation using the initial tap position that is the initial value of the tap position of the step voltage regulator that controls the voltage of the power system. The power flow calculation device further includes a storage unit that stores voltage stability information indicating a correspondence between input data and an initial tap position that suppresses divergence in power flow calculation, and a storage unit that reads voltage stability information from the storage unit, and reads out the input data and readout voltage stability information from the storage unit. and an initial tap determination section that determines an initial tap position using the voltage stability information obtained and inputs the determined initial tap position to the power flow calculation section.

According to the present disclosure, it is possible to suppress divergence in power flow calculations.

A diagram showing a configuration example of a power flow calculation device according to Embodiment 1. A diagram showing an example of a power distribution system that is a target of power flow calculation in the power flow calculation device of Embodiment 1. A diagram showing a configuration example of a computer system that implements the power flow calculation device of Embodiment 1. Flowchart showing an example of a processing procedure in the power flow calculation device of Embodiment 1 A diagram showing an example of voltage stability information in Embodiment 1 A diagram showing another example of voltage stability information in Embodiment 1 Schematic diagram showing the relationship between voltage in the distribution line and change in SVR tap position in Embodiment 1 Diagram for explaining the effect of repeating power flow calculation in Embodiment 1 A diagram showing a configuration example of a power flow calculation device according to Embodiment 2 Flowchart showing an example of a processing procedure in the power flow calculation device of Embodiment 2

Below, a power flow calculation device and a power flow calculation program according to an embodiment will be explained in detail based on the drawings.

Embodiment 1.
FIG. 1 is a diagram showing a configuration example of a power flow calculation device according to a first embodiment. As shown in FIG. 1, the power flow calculation device 1 of this embodiment includes a storage section 10, an input data setting section 11, an initial tap determination section 12, a voltage optimization section 13, and a result output section 14. The power flow calculation device 1 of the present embodiment calculates the voltage distribution of the power system by performing power flow calculation in the power system such as the power distribution system. Hereinafter, a power distribution system will be described as an example of a power system, but the power system is not limited to a power distribution system.

FIG. 2 is a diagram showing an example of a power distribution system that is a target of power flow calculation in the power flow calculation device 1 of this embodiment. In the example shown in Fig. 2, distribution lines 22-1 and 22-2 are connected to an LRT (Load Ratio Control Transformer: transformer with on-load tap changer) 21 as a distribution transformer installed in a substation, etc. has been done. The voltage on the secondary side of the LRT 21 is a voltage exceeding 600 V and below 7 kV, which is called high voltage, and is, for example, about 6.6 kV. A plurality of loads and a plurality of generators are connected to the high voltage distribution lines 22-1 and 22-2 via transformers (not shown). Specifically, the load is, for example, consumer equipment that uses electricity, such as a general household, business office, or factory, but these consumer equipment may be aggregated in units of transformers, etc. . This transformer is a transformer called a pole transformer or a road transformer, and converts high voltage power into low voltage power such as 100V or 200V. Further, some of the loads and generators connected to the distribution lines 22-1 and 22-2 may be connected without using a transformer. An SVR 23-1 that controls the voltage of the distribution line 22-1 is connected to the distribution line 22-1, and an SVR 23-2 that controls the voltage of the distribution line 22-2 is connected to the distribution line 22-2. There is.

Although two distribution lines are shown in FIG. 2, the number of distribution lines is not limited to two, and may be one or three or more. In addition, although FIG. 2 shows an example in which SVRs 23-1 and 23-2 are connected to distribution lines 22-1 and 22-2, respectively, SVRs 23-1 and 23-2 are connected to distribution lines 22-1 and 22-2. The number is also not limited to the example shown in FIG. Furthermore, the number of loads and generators connected to each distribution line 22-1, 22-2 is not limited to the example shown in FIG. 2. Hereinafter, when each of the distribution lines 22-1 and 22-2 is shown without being individually distinguished, it will be referred to as the power distribution line 22, and when each of the SVR23-1 and 23-2 is shown without being individually distinguished, it will be referred to as SVR23. It is written as

Returning to the explanation of FIG. The storage unit 10 stores a system database including equipment information that is information regarding equipment connected to the power distribution system, a load power generation database including information on load amount and power generation amount, and voltage stability information.

The equipment information is information regarding equipment in the power distribution system, and includes, for example, the position in the power distribution system of each equipment such as the load, generator, and SVR 23 connected to the power distribution line 22. The equipment information also includes information indicating the length of the distribution line 22 and information indicating the connection relationship of the distribution line 22. As shown in FIG. 2, since a power distribution system generally includes a plurality of power distribution lines 22, the connection position of equipment on the power distribution line is stored in the system database for each power distribution line 22. The connection position is indicated by, for example, the distance from the LRT 21, that is, the distance from the sending point. Alternatively, the connection position may be indicated by impedance.

The load power generation amount information, which is information indicating the load amount and power generation amount in the power distribution system, includes the load amount of each load connected to the power distribution system and the power generation amount of the generator. The load amount and the amount of power generation are represented by active power and reactive power, respectively. The load power generation amount information is calculated according to, for example, the measurement results of electric power in the distribution line 22, the measurement results of electric power in the low-voltage system, and the like. When the power flow calculation device 1 is used for monitoring and controlling a power distribution system, the measurement results may be stored as they are in the load power generation database as load power generation amount information. When the power flow calculation device 1 performs power flow calculations in the power distribution system in the future, past measurement results are accumulated so that predicted values of load amount and power generation amount can be calculated. For example, the tidal flow calculation device 1 or another device accumulates measurement results along with at least one attribute of season, month, day of the week, time of day, etc., and calculates an average value for each attribute. As a result, the load amount and power generation amount according to the attribute are calculated, and the results are stored in the load power generation database of the storage unit 10 as load power generation amount information. The attributes to be considered are not limited to these, and may include temperature, weather, etc.

The voltage stability information is information used to determine the initial tap position of the SVR 23 in the power flow calculation described later. Voltage stability information is information that shows the correspondence between input data and the initial tap position that suppresses divergence in power flow calculations. This is information indicating the relationship between the sum of units and the initial tap position of the SVR 23 that suppresses divergence in power flow calculation. Details of the voltage stability information will be described later.

The input data setting unit 11 sets input data for power flow calculation based on the system database and the load generation database stored in the storage unit 10 and outputs the set input data to the initial tap determination unit 12. In detail, for example, the input data setting unit 11 extracts information on equipment connected to the distribution line 22 that is the target of the power flow calculation from the grid database, and sets part of the input data in the power flow calculation based on the extracted information. Calculate the impedance of each node. In addition, the input data setting unit 11 calculates the load amount and power generation amount of each facility based on the attributes of the period targeted for power flow calculation and the load power generation database, and calculates the power flow based on the calculated load amount and power generation amount. Determine the active power and reactive power of each node that will be part of the input data in . The input data setting unit 11 accepts input of information related to the power flow calculation, such as the period for which the power flow is to be calculated and the distribution line 22 that is the target of the power flow calculation, and based on the received information, inputs the input data using the above-mentioned database or the like. May be set.

The initial tap determination unit 12 reads voltage stability information from the storage unit 10, and controls divergence in the power flow calculation based on the input data input from the input data setting unit 11 and the read voltage stability information. , determine the initial value of the tap position of the SVR 23 in the power flow calculation, that is, the initial tap position. Details of the operation of the initial tap determining section 12 will be described later. The initial tap determining unit 12 outputs the determined initial tap position and the input data input from the input data setting unit 11 to the voltage optimization unit 13.

The voltage optimization unit 13 performs power flow calculation based on the input data input from the initial tap determination unit 12 and the initial tap position, determines whether the voltage obtained by the power flow calculation is an appropriate value, and determines whether the voltage obtained by the power flow calculation is an appropriate value. If not, the initial tap position adjustment and power flow calculation are repeated until a proper value is obtained, and the obtained power flow calculation result is output to the result output section 14.

The voltage optimization unit 13 includes a power flow calculation unit 31, an end determination unit 32, and a tap adjustment unit 33, as shown in FIG. The power flow calculation unit 31 performs power flow calculation based on the input data input from the initial tap determination unit 12 and the initial tap position input from the initial tap determination unit 12 or the tap adjustment unit 33. That is, the power flow calculation unit 31 performs power flow calculation using input data including equipment information and load power generation information, and an initial tap position that is an initial value of the tap position of the SVR 23. Examples of specific methods for power flow calculation performed by the power flow calculation unit 31 include the BFS (Backward Forward Sweep) method, the Newton-Raphson method, and the DistFlow method. Specific methods are not limited to these. Moreover, as a method of the power flow calculation performed by the power flow calculation unit 31, a simplified calculation method such as the Fast Decoupled method can also be used. Note that when using a simplified calculation method, convergence may not occur due to the simplified calculation; however, by applying the initial tap position determination method of this embodiment, divergence can be achieved. You can reduce the probability.

The termination determination unit 32 performs termination determination, which is a determination as to whether or not to recalculate the tidal flow calculation. That is, the end determination unit 32 determines whether or not to end the repetition of the tidal flow calculation. Specifically, the end determination unit 32 determines whether the end condition for repeating the tidal flow calculation is satisfied. The termination condition is, for example, that the voltage obtained by power flow calculation is within the appropriate range, or that the voltage obtained by power flow calculation deviates from the appropriate range but the amount of deviation is below a threshold value. be. The end determination unit 32 determines that the power flow calculation should be recalculated when the end condition is not satisfied, that is, when the deviation amount of the voltage obtained by the power flow calculation from the appropriate range exceeds a threshold value. The termination determination section 32 outputs the power flow calculation result to the result output section 14 when the termination condition is satisfied. Note that the appropriate range is, for example, the range obtained by converting the voltage range of low-voltage distribution lines stipulated by the Electricity Business Act to high voltage, but in this embodiment, the appropriate range is the range that determines whether the initial tap position is appropriate. The scope is used in the Electricity Business Act, and does not have to match the scope stipulated by the Electricity Business Law. The tap adjustment unit 33 changes the initial tap position and inputs the changed initial tap position to the tidal flow calculation unit 31 when the end determination unit 32 determines that the tidal flow calculation should be recalculated.

The result output unit 14 outputs the power flow calculation results input from the termination determination unit 32. The result output unit 14 records the tidal current calculation result by outputting the tidal current calculation result to the storage unit 10 as data, for example. The power flow calculation results include, for example, a voltage distribution indicating the voltage at each node of the power distribution line 22, a current distribution indicating the current at each node of the power distribution line 22, and the like. Further, the result output unit 14 may display on the screen the voltage distribution, current distribution, etc. obtained as the result of the power flow calculation, or may transmit the result of the power flow calculation to an external device.

Next, the hardware configuration of the power flow calculation device 1 will be explained. The power flow calculation device 1 is realized by a computer system, that is, a computer. The number of computers that realize the power flow calculation device 1 may be one or more than one. For example, a computer that includes a computer that stores a grid database and a load generation database, a storage section 10 that stores voltage stability information, an input data setting section 11, an initial tap determination section 12, a voltage optimization section 13, and a result output section 14. The power flow calculation device 1 may be realized by the following. Moreover, the calculation by the power flow calculation unit 31 may be performed by a plurality of computers through distributed processing.

In the power flow calculation device 1 of this embodiment, the computer system functions as the power flow calculation device 1 by executing a power flow calculation program, which is a program in which processing in the power flow calculation device 1 is described, on the computer system. FIG. 3 is a diagram showing a configuration example of a computer system that implements the power flow calculation device 1 of this embodiment. As shown in FIG. 3, this computer system includes a control section 101, an input section 102, a storage section 103, a display section 104, a communication section 105, and an output section 106, which are connected via a system bus 107. There is.

In FIG. 3, the control unit 101 is, for example, a processor such as a CPU (Central Processing Unit), and executes a power flow calculation program in which processing in the power flow calculation device 1 of the present embodiment is described. The input unit 102 includes, for example, a keyboard and a mouse, and is used by a user of the computer system to input various information. The storage unit 103 includes various memories such as RAM (Random Access Memory) and ROM (Read Only Memory), and storage devices such as hard disks, and stores programs to be executed by the control unit 101 and necessary information obtained in the process. Store data, etc. The storage unit 103 is also used as a temporary storage area for programs. The display unit 104 is composed of an LCD (liquid crystal display panel) or the like, and displays various screens to the user of the computer system. The communication unit 105 is a receiver and a transmitter that perform communication processing. The output unit 106 is a printer or the like. Note that FIG. 3 is an example, and the configuration of the computer system is not limited to the example of FIG. 3.

Here, an example of the operation of the computer system until the power flow calculation program of this embodiment becomes executable will be described. In the computer system having the above-mentioned configuration, a power flow calculation program is stored, for example, from a CD-ROM or DVD-ROM set in a CD (Compact Disc)-ROM drive or DVD (Digital Versatile Disc)-ROM drive (not shown). 103. Then, when the load flow calculation program is executed, the load flow calculation program read from the storage unit 103 is stored in the main storage area of the storage unit 103. In this state, the control unit 101 executes processing as the power flow calculation device 1 of this embodiment according to the program stored in the storage unit 103.

In addition, in the above description, a CD-ROM or DVD-ROM is used as a recording medium to provide a program that describes the processing in the power flow calculation device 1. However, the configuration of the computer system and the program to be provided are not limited to this. Depending on the capacity of the computer, for example, a program provided via a transmission medium such as the Internet via the communication unit 105 may be used.

As described later, the power flow calculation program of this embodiment uses input data including equipment information and load power generation information, and an initial tap position that is the initial value of the tap position of the SVR 23 to the power flow calculation device 1. The load flow calculation step is executed. Furthermore, the power flow calculation program of the present embodiment includes a storage step of storing voltage stability information in the storage unit 10 in the power flow calculation device 1, which indicates the correspondence between the input data and the initial tap position that suppresses divergence in the power flow calculation. , an initial tap determination step of reading voltage stability information from the storage unit 10, determining an initial tap position using the input data and the read voltage stability information, and inputting the position to the power flow calculation.

The input data setting section 11, initial tap determining section 12, and voltage optimization section 13 shown in FIG. 1 are realized by the control section 101 shown in FIG. The result output unit 14 shown in FIG. 1 is realized by the control unit 101, but when performing screen display, it is realized by the control unit 101 and the display unit 104. Further, the result output unit 14 is realized by the control unit 101 and the communication unit 105 when transmitting the power flow calculation results to another device. The storage unit 10 shown in FIG. 1 is realized by the storage unit 103 shown in FIG. 3. Furthermore, when the input data setting section 11 accepts input of information regarding power flow calculation, the input section 102 is also used to realize the input data setting section 11.

Next, the operation of this embodiment will be explained. FIG. 4 is a flowchart showing an example of a processing procedure in the power flow calculation device 1 of this embodiment. First, the input data setting unit 11 of the power flow calculation device 1 sets input data (step S1). Specifically, as described above, the input data setting unit 11 sets input data including active power and reactive power of each node in power flow calculation using information stored in the grid database and load generation database. , outputs the input data to the initial tap determining section 12.

The initial tap determination unit 12 sets the initial tap position of the SVR 23 based on the input data and voltage stability information (step S2). In detail, for example, the initial tap determination unit 12 calculates the active power P, which is the sum of the active powers of each node of the power flow calculation distribution line 22, and calculates the reactive power Q, which is the sum of the reactive power of each node. do. Then, initial tap positions corresponding to the calculated values of active power P and reactive power Q are calculated based on the voltage stability information stored in the storage unit 10. The voltage stability information is, for example, information indicating the correspondence between the values of active power P and reactive power Q and the value of the initial tap position that suppresses divergence in power flow calculation.

Here, we will give examples of conditions that tend to cause divergence in power flow calculations. An example of a condition where divergence is likely to occur in power flow calculations is when the voltage monotonically decreases from the sending point to the terminal. This occurs when there are many loads connected to the distribution line 22, when loads with a large amount of load are connected, or when reactive power is large. Therefore, in general, the ease with which divergence occurs in power flow calculations depends on the total active power and the total reactive power of the distribution line 22. On the other hand, even under conditions where divergence is likely to occur, if voltage control by the SVR 23 is taken into consideration, the power flow calculation can easily converge. Generally, if the tap position of the SVR 23 is raised to the maximum value, the possibility that the power flow calculation will converge increases. Therefore, by setting the initial tap position of the SVR 23 to the maximum value in all cases, divergence can be suppressed. In order to suppress divergence, it is effective to set the initial tap position of the SVR23 to the maximum value, but on the other hand, if the initial tap position is set to the maximum value, the voltage may rise too much and deviate from the appropriate range. be. For this reason, it is desirable to suppress divergence in power flow calculations while suppressing deviation from the appropriate range. Therefore, in this embodiment, information indicating the correspondence between the values of active power P and reactive power Q and the value of the initial tap position that suppresses divergence in power flow calculation is predetermined as voltage stability information. Set the initial tap position using . As a result, in this embodiment, deviation from the appropriate range is suppressed and divergence of the power flow calculation is suppressed.

FIG. 5 is a diagram showing an example of voltage stability information according to this embodiment. In FIG. 5, the horizontal axis shows the above-mentioned active power P, and the vertical axis shows the above-mentioned reactive power Q. If the active power P and reactive power Q calculated based on the input data are within the region 211, there is a low possibility that the power flow calculation will diverge even if the initial tap position is set to a position where voltage control is not performed, that is, a transparent position. . The region 211 is a region above the first threshold value 201 and inside the first threshold value 201 shown in FIG. Hereinafter, when each threshold value is defined two-dimensionally by two variables as shown in FIG. 5, when the active power P and the reactive power Q are above the threshold value, This indicates that the point is in an outer region, and when the active power P and reactive power Q are less than the threshold value, it indicates that the point is inside the threshold value. On the other hand, when the active power P and the reactive power Q calculated based on the input data are at points outside the region 211, if the initial tap position is set to the transparent position, there is a high possibility that the power flow calculation will diverge. Regarding reactive power Q, since it is lagged reactive power (reactive power is a positive value), when calculating the sum of reactive power, leading reactive power (reactive power is a negative value) is not taken into account and lagging reactive power is calculated. The total sum of only the power may be determined, and the threshold value may also be determined regarding the delayed reactive power as shown in FIG.

Additionally, if the active power P and reactive power Q calculated based on the input data are within the region 212, there is a possibility that the power flow calculation will diverge if the initial tap position is set one or more steps higher than the clear-through position. low. The area 212 is above the second threshold 202 shown in FIG. 5, and is an area inside the second threshold 202 and outside the first threshold 201. Note that raising the tap position means increasing the number of stages in the direction of boosting the secondary side voltage of the SVR 23. On the other hand, when the active power P and reactive power Q calculated based on the input data are points outside the area 212, there is a possibility that the power flow calculation will diverge even if the initial tap position is raised one step from the clear-through position. It gets expensive.

Additionally, if the active power P and reactive power Q calculated based on the input data are within the region 213, there is a possibility that the power flow calculation will diverge if the initial tap position is set two or more steps higher than the clear-through position. low. The area 213 is above the third threshold 203 shown in FIG. 5, and is an area inside the third threshold 203 and outside the second threshold 202. On the other hand, when the active power P and reactive power Q calculated based on the input data are outside the area 213, that is, within the area 214, even if the initial tap position is raised two steps from the through position, the power flow calculation is more likely to diverge.

The first threshold value 201, second threshold value 202, and third threshold value 203 shown in FIG. This is determined by determining whether or not it has diverged. By determining the first threshold 201, second threshold 202, and third threshold 203 shown in FIG. 1, the regions 211, 212, 213, and 214 determined by these thresholds can be The initial tap position corresponding to is determined in advance. In the example shown in FIG. 5, the initial tap positions corresponding to the active power P and the reactive power Q calculated based on the input data are set as the transparent position in the area 211, one step higher than the transparent position in the area 212, and one step higher than the transparent position in the area 213. The area 214 is raised two steps from the transparent position, and the region 214 is raised three steps from the transparent position. Note that the example shown in FIG. 5 shows an example in which the tap position of the SVR 23 can be raised by a maximum of three steps from the clear through position, so raising the tap position by three steps from the through position requires setting the tap position to the maximum. It means that.

As shown in FIG. 5, the first threshold 201, the second threshold 202, and the third threshold 203 are functions of active power P and reactive power Q, respectively. The voltage stability information is, for example, table-format information indicating the corresponding initial tap position for each region of region 211, region 212, region 213, and region 214, that is, for each value range of active power P and reactive power Q. It is.

For example, when the active power P and the reactive power Q calculated based on the input data are indicated by a point 220, since the point 220 is within the area 213, the initial tap determination unit 12 changes the initial tap position from the transparent position to the point 220. Set it to a raised position.

FIG. 6 is a diagram showing another example of voltage stability information according to this embodiment. In FIG. 6, the horizontal axis shows the above-mentioned active power P, and the vertical axis shows the above-mentioned reactive power Q. In FIG. 6, a threshold value 204 is determined, and in a region 215 that is above the threshold value 204 and inside the threshold value 204, there is a low possibility that the power flow calculation will diverge even if the initial tap position is the clear-through position. . On the other hand, in the region 216 outside the threshold value 204, if the initial tap position is set to the transparent position, there is a high possibility that the power flow calculation will diverge. The threshold value 204 is also determined in advance by simulation, as in the example of FIG. In the example shown in FIG. 6, there are two cases: whether the active power P and the reactive power Q calculated based on the input data are equal to or less than the threshold value 204. In this case, if the active power P and reactive power Q calculated based on the input data are less than or equal to the threshold 204, that is, within the region 215, the initial tap determination unit 12 sets the initial tap position to the transparent position. do. Further, when the active power P and the reactive power Q calculated based on the input data exceed the threshold value 204, that is, within the region 216, the initial tap determining unit 12 raises the initial tap position from the clear-through position.

When using the voltage stability information shown in FIG. 6, the initial tap position when the active power P and reactive power Q calculated based on the input data are within the area 216 may be set to, for example, the maximum value that can be set. I can do it. When the active power P and reactive power Q calculated based on the input data are within the region 216, the initial tap position does not have to be the maximum value, but from the viewpoint of suppressing divergence, it is set to a value close to the maximum value. That is desirable. In this case, there is a possibility that the voltage obtained as a result of the power flow calculation is too high than the original voltage. Since the adjustment is performed to lower the position, the initial tap position can be appropriately set.

The voltage stability information shown in FIGS. 5 and 6 is an example, and the voltage stability information is not limited thereto. The number of threshold values can be changed as appropriate depending on the number of tap stages of the SVR 23 that can be set. Further, in the example shown in FIG. 5, one threshold value corresponds to one stage of taps, but a threshold value may be determined for every two stages. Further, in the examples shown in FIGS. 5 and 6, the initial tap position is determined according to the active power P and the reactive power Q, but the invention is not limited to this. The initial tap position may be determined accordingly. For example, regardless of reactive power Q, if active power P is less than a threshold value, the initial tap position is set to the transparent position, and if active power P is greater than or equal to the threshold value, the initial tap position is set to the maximum value. Voltage stability information may be determined in a corresponding manner.

Furthermore, the voltage stability information may be determined so that the initial tap position is determined using the length of the distribution line 22. Generally, the longer the distribution line 22 is, the more likely it is that the power flow calculation will diverge. For this reason, a threshold value in a three-dimensional space is determined using three parameters: active power P, reactive power Q, and the length of the distribution line 22, and an initial tap position is determined for each three-dimensional area separated by the threshold value. may be determined in advance, and information indicating these correspondences may be used as voltage stability information. Further, the initial tap position may be determined based only on the length of the distribution line 22. Further, the voltage stability information may be determined so that the initial tap position is determined using the impedance of the wiring line 22 instead of the length of the distribution line 22. For example, similarly to the case where the length of the distribution line 22 is used, a threshold value in a three-dimensional space is determined using three parameters: active power P, reactive power Q, and impedance of the distribution line 22, and the threshold value is Initial tap positions may be determined for each divided three-dimensional area, and information indicating these correspondences may be used as voltage stability information, or the initial tap positions may be determined based only on the impedance of the wiring line 22. good.

Note that when a plurality of SVRs 23 are connected to one power distribution line 22, the initial tap positions of these plurality of SVRs 23 are all set to the same value.

5 and 6 show an example in which the initial tap position is determined based on the sum of active power and the sum of reactive power in the distribution line 22, but the distribution line 22 is divided into a plurality of sections, The initial tap position may be determined using the respective sums of active power and reactive power. Even if the load is the same, the degree of influence regarding whether the power flow calculation diverges is different between the vicinity of the start point and the vicinity of the end of the distribution line 22. Therefore, a threshold value as shown in FIG. 5 or 6 may be determined for each section. In this case, the initial tap position of the SVR 23 within the section may be determined for each section, or the initial tap position of the section with the strictest conditions may be set as the initial tap position of all the SVRs 23.

That is, the voltage stability information is, for example, information indicating the correspondence between power information that is at least one of the total active power and the total reactive power of each distribution line 22 and the initial tap position corresponding to the power information. It is. In this case, the initial tap determination unit 12 calculates power information based on the active power and reactive power that are the load power generation information of the input data, and determines the initial tap position based on the power information and voltage stability information. In another example, the voltage stability information includes power information that is at least one of the total active power and the total reactive power for each distribution line in the power system, the length of the distribution line 22, the power information, and the length of the distribution line 22. This is information indicating the correspondence between the initial tap position and the length of the distribution line. In this case, the initial tap determination unit 12 calculates the power information based on the load power generation amount information of the input data, calculates the length of the distribution line 22 based on the equipment information of the input data, Determine the initial tap position based on the length and voltage stability information. Furthermore, in another example, the voltage stability information is information indicating the correspondence between the length of the distribution line 22 and the initial tap position corresponding to the length of the distribution line 22. In this case, the initial tap determination unit 12 calculates the length of the distribution line based on the equipment information of the input data, and determines the initial tap position based on the length of the distribution line and voltage stability information.

Since the voltage stability information varies depending on the number of equipment connected to the distribution line 22, etc., it may be stored in the storage unit 10 for each distribution line 22. Alternatively, voltage stability information may be determined for the distribution line 22 which is the most severe, that is, where divergence is most likely to occur, among the plurality of distribution lines 22, and the voltage stability information may be determined regardless of the distribution line 22.

Returning to the explanation of FIG. 4. After step S2, the power flow calculation unit 31 uses the input data and the initial tap position to perform power flow calculation (step S3). Next, the end determination unit 32 determines whether or not to end the repetition of the tidal flow calculation (step S4). For example, as described above, the termination determination unit 32 determines whether the voltage obtained by the power flow calculation is within an appropriate range, or whether the voltage obtained by the power flow calculation deviates from the appropriate range but the amount of deviation is within a threshold. If it is less than or equal to the value, it is determined that the repetition of the load flow calculation is to be ended.

FIG. 7 is a schematic diagram showing the relationship between the voltage in the distribution line 22 and the change in the tap position of the SVR 23 according to the present embodiment. At the top of FIG. 7, equipment connected to the power distribution line 22-1 is schematically shown. The middle row of FIG. 7 shows a case where the tap position of the SVR 23-1 of the distribution line 22-1 is changed to lower the voltage, that is, a case where the SVR tap is lowered, and the lower row of FIG. This shows a case where the tap position of the SVR 23-1 of the power distribution line 22-1 is changed in the direction of increasing the voltage, that is, a case where the SVR tap is raised. The horizontal axes of the middle and lower diagrams in FIG. 7 are distances from the sending point. An appropriate range 51 in FIG. 7 indicates an appropriate range regarding the voltage of the power distribution line 22.

In the example in the center stage of FIG. 7, the voltage 52 of the power distribution line 22 exceeds the appropriate range 51 when voltage control by the SVR 23-1 is not performed. The SVR 23-1 controls the tap position so that the voltage of the power distribution line 22-1 falls within the appropriate range 51, and in this example, the tap position of the SVR 23-1 is changed in the direction of lowering the voltage. Voltage 53 indicates the voltage of power distribution line 22-1 when the tap position of SVR 23-1 is changed in the direction of lowering the voltage.

In the example shown in the lower part of FIG. 7, the voltage 54 of the power distribution line 22 is below the appropriate range 51 when voltage control by the SVR 23-1 is not performed. In this example, the tap position of the SVR 23-1 is changed in the direction of increasing the voltage. Voltage 55 indicates the voltage of distribution line 22-1 when the tap position of SVR 23-1 is changed in the direction of increasing the voltage.

In this way, the SVR 23 changes the tap position so that the voltage of the distribution line 22 falls within the appropriate range, but when performing power flow calculations, it is difficult to know which tap position each SVR 23 is actually set to. I don't know in general. Therefore, when performing a power flow calculation, an initial tap position is given, and the tap position of the SVR 23 is changed during repeated calculations in the power flow calculation. In this way, the voltage of the power distribution line 22 is controlled by the SVR 23 so as not to deviate from the appropriate range, within a range that can be controlled by the SVR 23 . In this embodiment, as described above, the initial tap position of the SVR 23 is determined so as to suppress the divergence of the power flow calculation, but the initial tap position may be different from the original tap position. In particular, in the example shown in Figure 6, if the initial tap position is set to the maximum value when active power P and reactive power Q are above the threshold, the power flow calculation will raise the voltage too much even if it no longer diverges. Therefore, it is possible that the voltage in the power flow calculation results may deviate from the appropriate range. In this case, although the divergence is suppressed, the initial tap position is not appropriate, so it is desirable to change the initial tap position. Therefore, in the present embodiment, the end determination unit 32 compares the voltage of the power flow calculation result with the appropriate range, and determines whether the voltage of the power flow calculation result is within the appropriate range or even if it deviates from the appropriate range. If the deviation amount is less than or equal to the threshold value, it is determined that the process is to be terminated. On the other hand, the end determination unit 32 determines not to perform the process if the above conditions are not met. That is, the end determination unit 32 determines that the initial tap position is not appropriate, so the initial tap position is changed and the power flow calculation is performed again.

Returning to the explanation of FIG. 4. When the end determination unit 32 determines to end the process (Step S4 Yes), the result output unit 14 outputs the power flow calculation result (Step S6) and ends the process. Specifically, when the end determination unit 32 determines to end the process, it outputs the result of the power flow calculation to the result output unit 14, and the result output unit 14 outputs the result of the power flow calculation. If the end determination unit 32 determines not to end the process, that is, if it determines to recalculate the tidal flow calculation (No in step S4), the tap adjustment unit 33 changes the tap position (step S5). After step S5, the initially changed tap position is input to the power flow calculation unit 31 as the initial tap position, and the processing from step S3 is repeated. In step S3 from the second time onward, the tidal current calculation unit 31 uses the initial tap position and input data input from the tap adjustment unit 33 when the end determination unit 32 determines to recalculate the tidal current calculation. Perform tidal flow calculations.

Through the above processing, the initial tap position is determined based on the input data of the tidal flow calculation in the tidal flow calculation device 1 of the present embodiment, so that divergence in the tidal current calculation can be suppressed. As shown in Figure 5, when determining the initial tap position in stages using multiple thresholds as voltage stability information, the initial tap position must be set appropriately in the first power flow calculation. Since there is a high possibility that there is, the power flow calculation device 1 does not need to perform step S4 and step S5. That is, the power flow calculation device 1 does not need to include the end determination section 32 and the tap adjustment section 33.

On the other hand, when the initial tap position is determined using one threshold value as voltage stability information as shown in FIG. 6, the initial tap position is set to the maximum value when the threshold value is exceeded. In this case, there is a possibility that the voltage obtained as a result of the power flow calculation is much higher than the original voltage. Therefore, in this embodiment, as shown in FIG. 4, if the voltage obtained by the power flow calculation deviates from the appropriate range and the amount of deviation exceeds the threshold, the initial tap position is changed and the power flow is calculated again. Since this is repeated, the initial tap position can be appropriately set even if the initially set initial tap position is not appropriate.

FIG. 8 is a diagram for explaining the effect of repeating the power flow calculation according to this embodiment. FIG. 8 shows an example of the voltage distribution obtained from the power flow calculation results when the initial tap position is set to the maximum value when the active power P and reactive power Q are exceeded, as shown in FIG. 6. . The horizontal axis indicates each node in the power distribution line 22. The upper left diagram in FIG. 8 shows the power flow calculation result when the tap position is set to the maximum value in the first initial tap position setting, that is, the first power flow calculation result. Further, in the example shown in FIG. 8, the tap adjustment unit 33 lowers the tap position one step at a time for each power flow calculation. The upper right figure shows the result of the first power flow calculation after the deviation from the appropriate voltage exceeds the threshold value and the initial tap position is changed. The result of the power flow calculation after being performed once is shown. The lower left figure shows the tidal flow calculation result after the tap position has been changed twice, and the lower right figure shows the tidal flow calculation result after the tap position has been changed 5 times.

As shown in FIG. 8, the initial power flow calculation results show that the voltage increases toward the terminal side and deviates from the appropriate range. As the number of times the initial tap position is changed increases, the voltage gradually decreases, and after the tap position has been changed five times, it almost falls within the appropriate voltage range. As a result, the power flow calculation device 1 finishes repeating the power flow calculation after changing the initial tap position five times. In this embodiment, by adjusting the initial tap position in this way, it is possible to prevent the power flow calculation results from becoming inappropriate.

As described above, in the power flow calculation device 1 of the present embodiment, the initial tap position is determined based on the input data of the power flow calculation, so that divergence in the power flow calculation can be suppressed. In addition, the power flow calculation device 1 further performs a process of repeatedly changing the initial tap position and performing power flow calculation again when the voltage obtained by power flow calculation deviates from the appropriate range and the amount of deviation exceeds a threshold value. Then, even if the initially set initial tap position is not appropriate, the initial tap position can be appropriately set.

Embodiment 2.
FIG. 9 is a diagram showing a configuration example of a power flow calculation device according to the second embodiment. As shown in FIG. 9, the power flow calculation device 1a of the present embodiment includes an initial tap determination section 12a and a voltage optimization section 13a instead of the initial tap determination section 12 and voltage optimization section 13 of the first embodiment. The rest is the same as the power flow calculation device 1 of the first embodiment. Hereinafter, components having the same functions as those in Embodiment 1 will be given the same reference numerals as in Embodiment 1, and redundant explanation will be omitted. Hereinafter, differences from Embodiment 1 will be mainly explained.

The power flow calculation device 1a of this embodiment is realized by a computer system like the power flow calculation device 1 of the first embodiment. The configuration of a computer system that realizes the power flow calculation device 1a of this embodiment is the same as that of the first embodiment. Similarly to the first embodiment, the power flow calculation device 1a of the present embodiment is realized by a computer system executing a power flow calculation program in which the processing of the power flow calculation device 1a is described.

The voltage optimization unit 13a of this embodiment includes a power flow calculation unit 31, an end determination unit 32, a tap adjustment unit 33, and a convergence determination unit 34. The power flow calculation section 31, the end determination section 32, and the tap adjustment section 33 are the same as those in the first embodiment. In this embodiment, after the tidal current calculation by the tidal current calculation unit 31, the convergence determination unit 34 determines whether the tidal current calculation has converged. The end determination unit 32 performs end determination in the same manner as in the first embodiment when the convergence determination unit 34 determines that the power flow calculation has converged.

When the convergence determination unit 34 determines that the tidal flow calculation has not converged, the convergence determination unit 34 instructs the initial tap determination unit 12a to raise the initial tap position, and the initial tap determination unit 12a determines that the current tap position The initial tap position is changed to a tap position that increases the voltage of the distribution line 22, and the changed initial tap position is input to the power flow calculation unit 31. Specifically, the convergence determination unit 34 instructs the initial tap determination unit 12a to set the initial tap position to the maximum value, for example.

The initial tap determination unit 12a inputs the reset initial tap position to the power flow calculation unit 31. The tidal current calculation unit performs tidal current calculation using the changed initial tap position and input data input from the initial tap determination unit 12a when the convergence determination unit 34 determines that the tidal current calculation has not converged. As a result, the power flow calculation is performed again with the initial tap position raised from the previous power flow calculation, and the possibility of convergence becomes higher than before raising the initial tap position.

FIG. 10 is a flowchart showing an example of the processing procedure in the power flow calculation device 1 of this embodiment. Steps S1 to S3 are the same as in the first embodiment. After step S3, the convergence determination unit 34 determines whether the power flow calculation performed in step S3 has converged (step S7). If the power flow calculation has converged (step S7 Yes), the processes from step S4 onwards are performed. Steps S4, S5, and S6 are the same as in the first embodiment.

If the power flow calculation has not converged (No in step S7), the convergence determination section 34 instructs the initial tap determination section 12a to reset the initial tap position, and the processing from step S2 is repeated. As described above, when resetting the initial tap position, the initial tap determining unit 12a raises the initial tap position from the previous time.

As described above, in this embodiment, it is determined whether or not the power flow calculation converges, and if it does not converge, the initial tap position is reset. Therefore, if the voltage stability information is appropriately set, the same operation as in Embodiment 1 is performed to suppress divergence in power flow calculation, and the voltage Even if the initial tap position is not properly set using the stability information, by resetting the initial tap position, it is possible to prevent the power flow calculation from diverging again. The processes of this embodiment other than those described above are the same as those of the first embodiment.

The configurations shown in the embodiments above are merely examples, and can be combined with other known techniques, or can be combined with other embodiments, within the scope of the gist. It is also possible to omit or change part of the configuration.

Reference Signs List 1, 1a power flow calculation device, 10 storage unit, 11 input data setting unit, 12, 12a initial tap determination unit, 13, 13a voltage optimization unit, 14 result output unit, 31 power flow calculation unit, 32 end determination unit, 33 tap Adjustment unit, 34 Convergence determination unit.

Claims (8)

Input data including equipment information regarding equipment in the power system, load power generation amount information indicating the load amount and power generation amount in the power system, and an initial value of a tap position of a step voltage regulator that controls the voltage of the power system. a tidal flow calculation unit that performs tidal flow calculation using a certain initial tap position;
a storage unit that stores voltage stability information indicating a correspondence between the input data and the initial tap position that suppresses divergence in the power flow calculation;
an initial tap determining unit that reads the voltage stability information from the storage unit, determines the initial tap position using the input data and the read voltage stability information, and inputs the initial tap position to the power flow calculation unit;
A tidal flow calculation device comprising: A termination determination is performed to determine whether or not to recalculate the power flow calculation, and if the amount of deviation of the voltage in the power system obtained by the power flow calculation from a predetermined appropriate range exceeds a threshold value. , an end determination unit that determines that the tidal flow calculation is to be recalculated;
a tap adjustment unit that changes the initial tap position and inputs the changed initial tap position to the tidal flow calculation unit when the end determination unit determines to recalculate the tidal flow calculation;
Equipped with
The power flow calculation unit may perform power flow calculation using the initial tap position input from the tap adjustment unit and the input data when the end determination unit determines that the power flow calculation should be recalculated. The power flow calculation device according to claim 1, characterized by: a convergence determination unit that determines whether the power flow calculation has converged;
Equipped with
The initial tap determination unit is configured to set the initial tap position to a tap that increases the voltage of the power system from the currently set initial tap position when the convergence determination unit determines that the power flow calculation has not converged. position, input the changed initial tap position to the tidal flow calculation section,
The power flow calculation unit calculates the power flow using the changed initial tap position input from the initial tap determination unit and the input data when the convergence determination unit determines that the power flow calculation has not converged. The power flow calculation device according to claim 1, wherein the power flow calculation device performs calculation. a convergence determination unit that determines whether the power flow calculation has converged;
Equipped with
The initial tap determination unit is configured to set the initial tap position to a tap that increases the voltage of the power system from the currently set initial tap position when the convergence determination unit determines that the power flow calculation has not converged. position, input the changed initial tap position to the tidal flow calculation section,
The power flow calculation unit calculates the power flow using the changed initial tap position input from the initial tap determination unit and the input data when the convergence determination unit determines that the power flow calculation has not converged. do the calculations,
3. The power flow calculation device according to claim 2, wherein the end determination unit performs the end determination when the convergence determination unit determines that the power flow calculation has converged. The voltage stability information indicates a correspondence between power information that is at least one of a total active power and a total reactive power for each distribution line of the power system, and the initial tap position corresponding to the power information. information,
From claim 1, wherein the initial tap determining unit calculates the power information based on the load power generation amount information, and determines the initial tap position based on the power information and the voltage stability information. 4. The power flow calculation device according to any one of 4. The voltage stability information corresponds to power information that is at least one of the total sum of active power and the total sum of reactive power for each distribution line, and the length of the distribution line, and the power information and the length of the distribution line. Information indicating a correspondence with the initial tap position,
The initial tap determination unit calculates the power information based on the load power generation information, calculates the length of the distribution line based on the equipment information, and calculates the power information, the length of the distribution line, and the length of the distribution line. The power flow calculation device according to any one of claims 1 to 4, wherein the initial tap position is determined based on voltage stability information. The voltage stability information is information indicating a correspondence between the length of a distribution line of the power system and the initial tap position corresponding to the length of the distribution line,
The initial tap determining unit may calculate the length of the distribution line based on the equipment information, and determine the initial tap position based on the length of the distribution line and the voltage stability information. The power flow calculation device according to any one of claims 1 to 4. A tidal flow calculation device that performs tidal flow calculations,
Input data including equipment information regarding equipment in the power system, load power generation amount information indicating the load amount and power generation amount in the power system, and an initial value of a tap position of a step voltage regulator that controls the voltage of the power system. a tidal flow calculation step of performing tidal flow calculation using a certain initial tap position;
a storing step of storing voltage stability information in a storage unit indicating a correspondence between the input data and the initial tap position that suppresses divergence in the power flow calculation;
an initial tap determining step of reading the voltage stability information from the storage unit, determining the initial tap position using the input data and the read voltage stability information, and inputting the initial tap position to the power flow calculation;
A tidal flow calculation program characterized by being executed.

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