JP2024020085A - Power grid stabilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power grid stabilizer capable of keeping a stable state of a power grid even when a state of the power grid largely changes.

SOLUTION: A power grid stabilizer according to an embodiment comprises a selection unit, an electrical control estimation model generation unit, an electrical control machine correction unit, a first stage electrical control execution unit, a stability evaluation model generation unit and an additional electrical control execution unit. After an accident occurs, the additional electrical control execution unit selects and cuts off an additional electrical control machine when a generator is determined to lose synchronization on the basis of model definition information prepared in the stability evaluation model generation unit, a transition of phase angle deviation calculated using a measured value of a power grid, and a determination criterion.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2024,JPO&INPIT

Description

Embodiments of the present invention relate to system stabilization devices.

When a situation called a system accident such as a short circuit or a ground fault occurs in an electric power system due to a lightning strike or the like, the generators in the electric power system may be in an unstable state called a step-out. If the loss of synchronization is left untreated, the entire power system may fall into an unstable state. In this case, a system stabilization device is installed that maintains stable operation of most of the power system by turning some of the generators in the power system into a power breaker and cutting off the supply of power from the power breaker. Are known.

The grid stabilization device acquires grid information regarding the power grid at preset intervals. The grid stabilizing device uses the grid information to calculate transient stability when a grid fault occurs in a grid model that is a simulation model representing the power flow state of power in the power grid. The system stabilization device determines whether or not there is a step out of the generator based on the calculation result of the transient stability. When a generator out-of-step occurs, the grid stabilization device selects the electrical cutoff machine necessary to maintain the power grid in a stable state. Then, when a system fault occurs, the system stabilization device maintains the power system in a stable state by cutting off the supply of power from the selected power cutout machine (Non-Patent Document 1).

By the way, there are cases where the state of the power system changes significantly during the cycle of selecting the necessary power shedding machine. The electricity shedding machines selected in advance using the method of Non-Patent Document 1 may not be able to maintain the power system in a stable state, that is, it may be necessary to increase the electricity shedding machines. As an improvement measure to stabilize the power system, calculate the amount of power shedding required in a shorter cycle and add or change the necessary power shedding equipment to the previously selected power shedding equipment before an accident occurs. There is a known method for keeping it in place (Patent Documents 1 and 2). In addition, if it is determined that it is difficult to maintain a stable state based on measurement information after an accident occurs, a new electrical shedding machine is selected, and the electrical shedding machine that has been selected in advance by the method of Non-Patent Document 1 is used. A method is known in which a new electrical cutoff machine is cut off after the previous one is cut off (Patent Document 3).

In order to respond to various changes in the state of the power system, there are two methods: adding or changing the necessary power limiting devices before an accident occurs, as described above, and adding or changing new power limiting devices after shutting off a pre-selected power limiting device. It is conceivable to combine this with a method of shutting off the brake. However, if you simply combine Patent Document 1, which adds/changes a power cutter for renewable energy, and Patent Document 2, which adds/changes a power cutter for a synchronous generator, both However, there is a problem in that the necessary additions and changes are made, resulting in an excessive number of electrical curtailment devices.
The method of cutting off a new electrical shedding machine in Patent Document 3 does not assume that the electrical shedding machine will be added or changed, so it evaluates the electrical shedding machine before being added or changed, and then determines whether to use the new electrical shedding machine. There is an issue of excessive selection and blocking.

JP2021-69214A Patent No. 7002989 JP2022-38125A

“Appendix 2 Example of relay system to prevent synchronization”, October 2000, Technical Report of the Institute of Electrical Engineers of Japan, No. 801, p. 153-154

The problem to be solved by the present invention is to provide a system stabilization device that can maintain a stable state of the power system even if the state of the power system changes significantly.

The system stabilization device of the embodiment includes a selection unit, a power shedding estimation model generation unit, a power shedding correction unit, a first stage power shedding execution unit, a stability evaluation model generation unit, and an additional power shedding execution unit. and have. The selection unit acquires grid information representing characteristics of a power system having a generator at a preset period, and uses the grid information to create a system model that is a simulation model representing a power flow state of power in the power system. Create a system model, calculate the transient stability when a predetermined system fault occurs, and based on the calculation result of the transient stability, calculate the power output of the generator for each of the predetermined system faults. Select the first voltage cutter that cuts off the supply of. The power control estimation model generation unit generates power control from the system information based on power control information that is a combination of the system information and a first power control candidate for each of the predetermined system faults in the system model. Create a regression equation to predict the The electrical grid correction unit uses the regression equation, the grid information last acquired by the selection unit, and the grid information immediately before the predetermined grid fault occurs to determine the power system necessary for maintaining stability of the power system. A new power shedding device is added to the first power shedding device or the first power shedding device is changed based on the calculated amount of power shedding. The first-stage electrical curtailment execution unit transmits a command to cut off the first electrical curtailment machine added or changed by the electrical curtailment machine correction unit when a system fault occurs. The stability evaluation model generation unit generates model definition information for determining the change in phase angle deviation used to determine whether or not the generator is out of step from the measured values of the power system and generator before and after the occurrence of an accident, and The criteria to be used for determining the presence or absence are prepared from the immediately preceding transient stability calculation results. After the occurrence of an accident, the additional power control execution unit calculates the change in phase angle deviation calculated using the model definition information prepared by the stability evaluation model generation unit and the measured values of the power system, and based on the determination criteria. , if it is determined that the generator is out of step, an additional power cutter is selected and cut off.

FIG. 1 is a diagram showing the configuration of a system stabilizing device according to an embodiment. FIG. 3 is a diagram showing the configuration of a first-stage electrical curtailment machine selection section of the system stabilization device according to the embodiment. The figure which shows the structure of the electrical curtailment machine correction|amendment part of the system stabilization device of embodiment. The figure which shows the structure of the stability evaluation model generation part of the system stabilization device of embodiment. The figure explaining the processing content of the electric control synchronous machine determination part of the system stabilization device of embodiment. FIG. 3 is a diagram illustrating the processing contents of the power grid renewable energy determination unit of the system stabilization device according to the embodiment. The figure explaining the processing content of transient stability calculation of the system stabilization device of an embodiment. The figure explaining the processing content of the output change calculation part at the time of power cut of the system stabilization device of embodiment.

Hereinafter, a system stabilizing device according to an embodiment will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a power supply system according to an embodiment. As shown in FIG. 1, the power supply system includes a power system 1, a transmission system 10, and a system stabilization device 20. The power system 1 includes information terminals 11-1, 11-2, 11-3, 11-4, 11-5, control terminals 12-1, 12-2, buses 2-1, 2-2, 2-3, 2-4, 2-5, power transmission lines 3-1, 3-2, 3-3, 3-4, 3-5, transformers 4-1, 4-2, 4-3, 4-4, generator 5-1, 5-2, 5-3, 5-4 and circuit breakers 6-1, 6-2, 6-3, 6-4. In the following description, when there is no need to distinguish between the bus lines 2-1, 2-2, 2-3, 2-4, 2-5, and 2-6, they will be referred to as bus lines 2. In addition, if there is no need to distinguish between the power transmission lines 3-1, 3-2, 3-3, 3-4, and 3-5, they will be referred to as power transmission lines 3.

The generators 5-1, 5-2, 5-3, and 5-4 generate electricity using renewable energy such as sunlight and wind power, or exhaustible energy such as fossil fuel. The generators 5-1, 5-2, 5-3, and 5-4 supply the generated power to consumers via the power transmission line 3 and bus bar 2. In the following description, if there is no need to distinguish between the generators 5-1, 5-2, 5-3, and 5-4, they will be referred to as generators 5. In addition, asynchronously interconnected generators such as solar and wind power are referred to as renewable energy sources, and synchronously interconnected generators such as thermal, hydroelectric, and nuclear power are referred to as synchronous generators.

The transformer 4-1 transforms the voltage of the power generated by the generator 5-1 to a predetermined voltage. The transformer 4-2 transforms the voltage of the power generated by the generator 5-2 to a predetermined voltage. The transformer 4-3 transforms the voltage of the power generated by the generator 5-3 to a predetermined voltage. The transformer 4-4 transforms the voltage of the power generated by the generator 5-4 to a predetermined voltage. In the following description, the transformers 4-1, 4-2, 4-3, and 4-4 will be referred to as transformers 4 unless it is necessary to distinguish them.

The circuit breaker 6-1 cuts off the supply of electric power generated by the generator 5-1 to the consumer. The circuit breaker 6-2 cuts off the supply of electric power generated by the generator 5-2 to the consumer. The circuit breaker 6-3 cuts off the supply of electric power generated by the generator 5-3 to the consumer. The circuit breaker 6-4 cuts off the supply of electric power generated by the generator 5-4 to the consumer. In the following description, the circuit breakers 6-1, 6-2, 6-3, and 6-4 will be referred to as circuit breakers 6 unless it is necessary to distinguish them.

The information terminal 11-1 measures information (hereinafter referred to as system information) representing the characteristics of the power system 1 that supplies power from the generator 5 to consumers via the bus 2-1. Specifically, the information terminal 11-1 measures electrical information and system information. The electrical information is information regarding the power etc. supplied by the power transmission lines 3-1, 3-2, and 3-5 connected to the bus 2-1. The system information is connection information of the power transmission line 3-1, etc. The information terminal 11-2 measures system information representing the characteristics of the power system 1 that supplies power from the generator 5 to consumers via the bus 2-2. Specifically, the information terminal 11-2 is a system that includes electrical information on the power transmission lines 3-1 and 3-3 connected to the bus 2-2 and connection information on the power transmission lines 3-1 and 3-3. Measure information. The information terminal 11-3 measures system information representing the characteristics of the power system 1 that supplies power from the generator 5 to consumers via the bus 2-3. Specifically, the information terminal 11-3 is a system that includes electrical information on the power transmission lines 3-2 and 3-4 connected to the bus 2-3 and connection information on the power transmission lines 3-2 and 3-4. Measure information. The information terminal 11-4 measures system information regarding the power system 1 that supplies power from the generator 5 to consumers via the bus 2-4. Specifically, the information terminal 11-4 provides electrical information about the power transmission line 3-3 and circuit breakers 6-1 and 6-2 connected to the bus 2-4, and the transmission line 3-3 and circuit breakers 6-2. System information including connection information 1 and 6-2 is measured. The information terminal 11-5 measures system information regarding the power system 1 that supplies power from the generator 5 to consumers via the bus 2-5. Specifically, the information terminal 11-5 provides electrical information on the power transmission line 3-4 and circuit breakers 6-3 and 6-4 connected to the bus bar 2-5, as well as electrical information on the power transmission line 3-4 and circuit breakers 6-4 connected to the bus bar 2-5. 3. Measure the system information including the connection information of 6-4.

Here, the electrical information included in the system information is information regarding the active power and reactive power of the power transmission line 3 and the transformer 4, the active power and reactive power of the generator 5, the bus voltage applied to the bus bar 2, and the like. Further, the connection information included in the system information is information regarding the connection state between the power transmission line 3 and the transformer 4, and the like. In the following description, information terminals 11-1, 11-2, 11-3, and 11-4 will be referred to as communication terminals 11 when there is no need to distinguish them.

The control terminal 12-1 controls the circuit breakers 6-1 and 6-2 to control the interruption of power supply from the generators 5-1 and 5-2. Furthermore, the control terminal 12-2 controls the circuit breakers 6-3 and 6-4 to control the interruption of power supply from the generators 5-3 and 5-4. In the following description, if there is no need to distinguish between the control terminals 12-1 and 12-2, the control terminals 12-1 and 12-2 will be referred to as the control terminal 12.

In the power system 1, the range to the left from the power transmission line 3-5 for which system information cannot be obtained is referred to as an external system. The range to the right from power transmission line 3-5 where system information can be obtained is referred to as an internal system. The external system also includes a plurality of busbars 2, power transmission lines 3, transformers 4, generators 5, and the like.

The transmission system 10 includes a dedicated communication line and a communication network such as the Internet. The transmission system 10 transmits various information such as system information between the information terminal 11 and the system stabilizing device 20 and between the control terminal 12 and the system stabilizing device 20.

The system stabilizing device 20 acquires various information such as system information from the information terminal 11 via the transmission system 10. The system stabilizing device 20 determines, among the generators 5 included in the power system 1 , which power grid generators are necessary for maintaining the stability of power supply by the power system 1 based on the acquired various information. Here, the power cutter is a generator 5 that cuts off the supply of electric power.

The system stabilization device 20 includes a first-stage shedding machine selection section 30, a shedding estimation model generation section 40, a shedding machine correction section 50, a first-stage shedding execution section 60, and a stability evaluation model generation section. section 70 and an additional electrical control execution section 80. These components are realized by a hardware processor such as a CPU (Central Processing Unit) executing a program (software), or include storage areas in various storage devices. Some or all of these components are hardware (circuit parts) such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), and GPU (Graphics Processing Unit). (including circuitry), or may be realized by collaboration between software and hardware. The program may be stored in advance in a storage device (a storage device with a non-transitory storage medium) such as an HDD (Hard Disk Drive) or flash memory, or may be stored in a removable storage device such as a DVD or CD-ROM. It may be stored in a medium (non-transitory storage medium), and installed in the storage device by loading the storage medium into a drive device.

The configuration of the first stage electrical control machine selection section 30 will be explained with reference to FIG. 2.
The first stage breaker selection unit 30 includes a basic system storage unit 31, a system information collection unit 32, a system model creation unit 33, a stability calculation unit 34, a stabilization index change calculation unit 35, and a It includes an energy group determination section 36, a power cutter selection section 37, a calculation result collection section 38, and a calculation result storage section 39.
The basic system storage unit 31 stores the configuration of the target power system, power transmission lines, generator constants, and the like. The information stored by the basic system storage unit 31 is configuration information.
The system information collection unit 32 collects system information such as active power measured by the information terminal 11 via the transmission system 10.
The system model creation unit 33 collects basic system information from the basic system storage unit 31 and system information from the system information collection unit 32, and creates a system model.
The stability calculation unit 34 performs transient stability calculation using the system model created by the system model creation unit 33. The stabilization index change amount calculation section 35 collects the calculation results of the stability calculation section 34 and calculates a stabilization index. The stabilization index change amount calculation unit 35 calculates the amount of change in the stabilization index of synchronization stability when the supply of power supplied from the plurality of generators 5 in the power grid 1 that supplies power is reduced due to power restriction. Calculate.
The renewable energy group determination section 36 collects the processing results of the stabilization index change amount calculation section 35 and selects the plurality of generators 5 based on the amount of change in the stabilization index calculated by the stabilization index change amount calculation section 35. Group (classify into groups).
The power shedding machine selection unit 37 collects the calculation results of the stability calculation unit 34 and the processing results of the stabilization index change amount calculation unit 35, and selects a power shedding machine.
The calculation result collection unit 38 collects the calculation results of the stability calculation unit 34 and the processing results of the power cut machine selection unit 37.
The calculation result storage unit 39 stores information on the target power system, the power cut machine selection results, etc. compiled by the calculation result collection unit 38.

The configuration of the electrical curtailment correction unit 50 will be explained with reference to FIG. 3.
The electrical grid correction unit 50 includes a electrical grid synchronous machine determining unit 51 and an electrical grid renewable energy determining unit 52.
The power control synchronous machine determining unit 51 collects the system information obtained via the transmission system 10, the processing results of the first stage power control machine selection unit 30, and the processing results of the power control estimation model generation unit 40, and selects a synchronous generator. Determine.
The electric power restriction renewable energy determination unit 52 collects the system information obtained through the transmission system 10, the processing results of the first stage electric power restriction selection unit 30, and the processing results of the electric power restriction estimation model generation unit 40, and selects a renewable energy power source. Determine.

The configuration of the stability evaluation model generation section 70 will be explained with reference to FIG. 4.
The stability evaluation model generation unit 70 includes a determination criterion formulation unit 71, an output change model formulation unit 72, a stable system model formulation unit 73, and an unstable system model formulation unit 75.
The stability evaluation model generation unit 70 collects the processing results of the first stage electrical control machine selection unit 30.

The electricity shedding estimation model generation unit 40 creates an estimation model for determining the electricity shedding amount using the system model information stored in the calculation result storage unit 39 and the electricity shedding machine selection results.

The additional electricity restriction execution unit 80 is a functional unit that operates after an accident occurs in the power system. The additional power shedding execution unit 80 generates, by the stability evaluation model generation unit 70, whether or not to perform additional power shedding after the first power shedding machine has executed the power shedding when an accident occurs in the power system. Judgment is made using the function etc. If additional electricity shedding is required, the additional electricity shedding execution unit 80 selects a electricity shedding machine to be subjected to the electricity shedding.

(effect)
Here, the operation of each element included in the system stabilizing device 20 will be explained.
First, with reference to FIG. 2, the operation of the first stage electrical curtailment selection section 30 will be explained. The first-stage power breaker selection unit 30 selects a power breaker to be cut off when a system fault occurs. The pre-calculation described in the following explanation refers to this series of processing. Electricity control equipment includes synchronous generators and renewable energy power sources.

The system information collection unit 32 collects state quantities such as voltage, active power, and reactive power at various points in the power system from the measurement terminal 11 via the transmission system 10 at a fixed period such as one minute.

The system model creation unit 33 combines various state quantities of the power system collected by the system information collection unit 32 with constants such as the configuration of the power system and transmission lines stored in the basic system storage unit 31. The system model creation unit 33 constructs a system model necessary for calculating the transient stability of the power system.

The stability calculation unit 34 uses the system model constructed by the system model creation unit 33 to perform transient stability calculations when various preset assumed accidents occur. The stability calculation unit 34 determines whether the generator does not step out or steps out, that is, determines whether the power system is stable or unstable.

The stabilization index change amount calculation unit 35 and the renewable energy group determination unit 36 group together renewable energy power sources with similar stabilization effects into the same group, and select each group as candidates for electricity restriction.
Specifically, the stabilization index change amount calculation unit 35 calculates the amount of change in the stabilization index of synchronization stability when the supply of power supplied from the plurality of generators 5 in the power system 1 that supplies electric power is reduced. Calculate. First, the stabilization index change amount calculation unit 35 classifies the power flow cross section based on the system configuration (topology) of the power system 1 and the shutdown state of the generator 5.
After classifying the power flow cross sections as described above, the stabilization index change amount calculation unit 35 calculates the stabilization index change amount used for grouping the plurality of generators 5 by the renewable energy group determination unit 36 based on the power system 1. This is done for each classification of tidal flow cross section. The stabilization index change amount is an index indicating the stabilization effect due to a reduction or stoppage of the output power of the renewable energy power generation device 6.

If the result of the stability calculation unit 34 is unstable, the power cutout machine selection unit 37 selects a power cutout machine from the out-of-step generator and the renewable energy power source group. As an example, the shedding machine selection unit 37 selects a synchronous generator that is a candidate for shedding or a generator that loses synchronization second in the transient stability calculation results without shedding. From the results of the transient stability calculation when the energy power source group is shut off, the amount of change in active power before and after shutoff is determined. The electrical shedding machine selection unit 37 selects electrical shedding candidates with a large amount of variation as electrical shedding machines.

The calculation result collection unit 38 associates the system model used by the stability calculation unit 34, the calculation result of the stability calculation unit 34, and the power cutoff machine selection result of the power cutoff machine selection unit 37, and collects them as one data set. Hold.

The calculation result storage unit 39 stores the system model and calculation results compiled by the calculation result collection unit 38 for a long period of time, such as one year.

The electricity shedding estimation model generation unit 40 creates an estimation model for determining the electricity shedding amount from the past system model, transient stability calculation results, electricity shedding machine selection results, etc. stored in the calculation result storage unit 39. An example of the estimation model is a linear regression equation that uses the branch phase difference angle as input to obtain the electrical control amount. The branch phase difference angle can be roughly estimated by the product of the active power of the transmission line or transformer and its reactance. The electricity restriction estimation model generation unit 40 may be similar to the regression equation generation unit 30 described in Patent Document 2.

The electricity shedding machine correction unit 50 uses the regression equation for calculating the electricity shedding amount created by the electricity shedding estimation model generation unit 40, the information stored in the calculation result storage unit 39, and the system information obtained from the transmission system 10. The electrical curtailment correction unit 50 calculates the electrical curtailment amount at a cycle shorter than the processing cycle of the first stage electrical curtailment selection unit 30. The electrical shedding machine correction section 50 adds another electrical shedding machine to the electrical shedding machine selected by the first stage electrical shearing machine selection section 30, or adds another electrical shedding machine to the electrical shedding machine selected by the first stage electrical shedding machine selection section 30, as necessary. Change the selected electrical control device.

The electrical curtailment synchronous machine determination unit 51, which is one component of the electrical curtailment machine correction unit 50, will be explained.
The power restriction synchronous machine determining unit 51 uses the synchronous generator as a power restriction candidate, adds or changes a power restriction machine as necessary, and transmits the result to the first stage power restriction execution unit 60. The specific processing contents will be explained with reference to FIG.

In step S101, based on the system information obtained from the transmission system 10, a regression formula A corresponding to the latest system state and a system state at the time of pre-calculation are selected from among the regression formulas created by the electricity control estimation model generation unit 40. Select regression equation B corresponding to . The selection method is the same as in Patent Document 2.

In step S102, the amount of power restriction required in the latest system state is calculated using regression formula A and the latest system information. This calculation result is defined as the electric control amount A.

In step S103, the amount of power restriction required in the system state at the time of the pre-calculation is calculated using the regression formula B and the system information at the time of the pre-calculation. This calculation result is defined as the electric control amount B.

In step S104, the magnitudes of the electric control amount A and the electric control amount B are compared. If the electric control amount A is larger than the electric control amount B, the process advances to step S105. If the electricity reduction amount A is less than the electricity reduction amount B, the process ends without adding or changing electricity reduction equipment.

In step S105, a power reduction device is added or changed so that the increase in the power control amount is equal to or greater than the difference between the power control amount A and the power control amount B. For example, a generator whose active power is larger than the difference between the amount of electricity curtailment A and the amount of electricity curtailment B and which is the smallest is selected from among the electricity curtailment candidates set in advance, and the first-stage electricity curtailment is performed. It is added to the electrical control machine selected by the selection section 30.

As a result of the above, the amount of power restriction required in the latest system state is greater than the amount of power restriction required in the system state at the time of preliminary calculation, and the amount of power restriction required is greater than the amount of power restriction required in the system state at the time of preliminary calculation, and the amount of power restriction is greater than that of the power restriction device selected by the first stage power breaker selection unit 30. A curtailer is added to increase the curtailment amount only when the quantity is required.

The electricity curtailment renewable energy determining unit 52, which is one component of the electricity curtailment correction unit 50, will be explained.
The power restriction renewable energy determining unit 52 uses the renewable energy power source as a power restriction candidate, adds a power restriction machine as necessary, and transmits the result to the first stage power restriction execution unit 60. The specific processing contents will be explained with reference to FIG.

In step S201, it is determined whether or not the electricity curtailment machine selected by the first stage electricity curtailment machine selection unit 30 includes a renewable energy power source. If the selected electricity reduction machine includes a renewable energy power source, the process advances to step S202. If the selected electrical cutoff machine does not include a renewable energy power source, the process ends without adding the electricity cutoff machine.

In step S202, the total output of the renewable energy power source selected as a power breaker by the first stage power breaker selection unit 30 decreases due to changes in the weather, etc., and the first stage power breaker selection unit 30 determines that the total output is It is determined whether or not the amount of electricity control is smaller than the amount of electricity that was set. If the total output of the selected renewable energy power source is smaller than the power control amount, the process advances to step S203. If the total output of the selected renewable energy power source is not smaller than the electricity curtailment amount, the process is terminated without adding an electricity curtailment machine.

In step S203, based on the grid information obtained from the transmission system 10, a regression equation corresponding to the latest grid state is selected from among the regression equations created by the grid estimation model generation unit 40 for each renewable energy group that is a grid grid candidate. Pick out the formula. The selection method is the same as in Patent Document 2.

In step S204, the amount of power restriction is calculated for each renewable energy group of power restriction candidates using the regression equation selected in step S203 and the latest grid information. At this time, the amount of electricity curtailment of the renewable energy group selected by the first stage electricity curtailment machine selection unit 30 is also calculated using a regression formula. The amount of power shedding based on the regression formula for the renewable energy group selected by the first stage power shedding machine selection unit 30 is 0, and the amount of power shedding based on the regression formula for the renewable energy group that is a candidate for power shedding machine is 1. , the electric control amount will be explained as 2. Here, in order to simplify the explanation, there are two renewable energy groups of power cutout machine candidates to be added as necessary, but there may be three or more renewable energy groups.

In step S205, the electricity reduction amount 1 and the electricity reduction amount 2 are compared, and the smaller renewable energy group is selected as the renewable energy group of the electricity reduction machine. In the following description, it will be assumed that the electric control amount 1 is smaller than the electric control amount 2.

In step S206, a renewable energy power source is selected from the renewable energy group and added to the power shedding machine so that the required power shedding amount calculated using equation (1) can be obtained in a renewable energy group with a power shedding amount of 1. . The shortage of the power shedding amount is the amount of power shedding that the first stage shedding machine selection unit 30 needed to maintain a stable system condition, that is, the amount of power shedding that was expected, and the amount of shedding that the first stage shedding machine selection unit 30 needed to maintain a stable system condition. This is the difference between the total output of the renewable energy group selected in If the total output of the renewable energy group with a power restriction amount of 1 is less than the required power restriction amount in equation (1), the required power restriction amount cannot be secured, and the shortfall will be obtained by the renewable energy group with a power restriction amount of 2. , perform the same process.

As a result of the above, when a renewable energy group is selected as a power shedding machine by the first stage power shedding machine selection unit 30, and the output of that renewable energy group decreases and does not reach the expected power shedding amount. By adding renewable energy power sources from other renewable energy groups to the power cut-off machine, the expected effect will be achieved.

Next, the processing contents of the stability calculation unit 34 will be explained with reference to FIG.

In step S301, the initial power flow is calculated using the system model created by the system model creation section 33. Processing based on this system model is also performed in each subsequent step.

In step S302, initial values of the generator 5 and the like are set based on the power flow calculation result in step S301.

In step S303, an admittance matrix (hereinafter referred to as Y matrix [Y]) is generated based on the system configuration.

In step S304, the inverse matrix [Y] ^-1 of the Y matrix is calculated.

In step S305, it is determined whether or not there is a change in the system configuration due to a system accident, a power outage, or the like. If there is a change in the system configuration, the process advances to step S306. If there is no change in the system configuration, the process advances to step S308.

In step S306, the Y matrix [Y] is changed based on the change in the system configuration.

In step S307, the inverse matrix [Y] ^-1 of the changed Y matrix is calculated.

In step S308, the injection current [I] is calculated based on the initial state or the state of the generator 5, etc. one hour ago ΔT.

In step S309, the node voltage [V] is calculated from the inverse matrix [Y] ^-1 of the Y matrix and the injection current [I].

In step S310, it is determined whether T _end is greater than T. If T _end is greater than T, the process advances to step S311. If T _end is not greater than T, the process ends. T _end is a reference value that specifies that the process will end when a predetermined time (cycle) has elapsed, and is the end time of the simulation. T is set to zero at the beginning of the flowchart shown in FIG.

In step S311, the state of the generator 5 etc. is calculated based on the calculated node voltage [V].

In step S312, ΔT is added to T to update the value of T, and the process proceeds to step S305.
As described above, transient stability calculation is performed.

The first-stage electrical shedding execution unit 60 performs electrical shedding based on the electrical shedding machine selection results for each assumed accident condition, which have been added or changed by the electrical shedding machine correction unit 50 as necessary, and information on the occurrence of an accident obtained from the transmission system 10. It extracts the electrical outages that correspond to the accident that occurred and outputs a control signal to shut off the electrical outages. The control terminal 12 that receives the control signal cuts off the corresponding generator from the grid.

The stability evaluation model generation unit 70 calculates constants and the like required by the additional electrical control execution unit 80.
The stability evaluation model generation section 70 uses the same method as the stability evaluation model generation section 40 described in Patent Document 3. However, the processing content of the output change model formulation unit 72 is different from that described in Patent Document 3.
Specifically, in Patent Document 3, the first stage power breaker selected by the first stage power breaker selection unit 30 is not changed. For this reason, based on the transient stability calculation results of the conditions for cutting off the electrical shedding machine selected as the first stage electrical shedding machine, the electrical shedding control unit 80 converts the electrical shedding machine into a one-machine infinite bus model, which is required by the additional electrical shedding execution unit 80. It is sufficient to calculate the amount of change in active power output at the time.
In contrast, in the present embodiment, the first-stage electrical breaker may be changed by the electrical breaker correction unit 50. For this reason, it is necessary to calculate the amount of change in active power output during power shedding converted into a single machine infinite bus model for all patterns of generators that can be used as the first stage power shedding machine. With reference to FIG. 8, a method of calculating the amount of change in output during power reduction will be explained.
FIG. 8 is a diagram illustrating the processing contents of the output change calculation unit 73 during electrical blackout of the system stabilization device 20 of the embodiment.

The simplest method for calculating the amount of change in active power output during power shedding converted to a single machine infinite bus model is to calculate the amount of change in active power output during power shedding converted to the single machine infinite bus model. The purpose was to calculate the transient stability of all combinations of a certain generator, but since the calculation time would be long, we devised a method that could be calculated in a short time.

In the transient stability calculation performed by the stability calculation unit 34, the calculation of the internal state of the synchronous generator, etc., and the calculation of the voltage, current, etc. of the power system are repeated in calculation time increments of 10 milliseconds, etc. Obtain the behavior of the synchronous generator and power system for about 10 to 20 seconds. The power shedding output change calculation unit 73 uses the inverse matrix of the admittance matrix (Y matrix) immediately before power shedding and the internal voltage of the synchronous generator obtained in the process of transient stability calculation to calculate a calculation time of 10 milliseconds. Calculate the amount of change in active power output during power shedding converted to a one-machine infinite bus model without performing step-by-step iterative calculations.

In step S401, the inverse matrix of the Y matrix immediately before power cutoff, the injection current vector, the node voltage, the generator active power, and the generator internal voltage are obtained from the transient stability calculation results. There is a relationship expressed by equation (2) between the inverse matrix of the Y matrix, the injection current vector, and the node voltage. Here, [V] is a node voltage vector, [Y] is a Y matrix, and [I] is an injection current vector.

In step S402, the active power of each generator obtained in step S401 is converted into a two-machine model of an unstable group and a stable group.

In step S403, the result of step S402 is used to calculate the amount of change in active power output during power outage converted into the one-machine infinite bus model. Calculate active power output.

In step S404, one of all combinations of generators that can be used as the first-stage electrical cut-off machine is set.

In step S405, the injection current corresponding to the electrical control target set in step S404 is changed to zero. This is based on the fact that the current injected into the power grid 1 from the generator to be shut down becomes zero after the shutoff.

In step S406, the voltage at each node is calculated using the above-mentioned equation (2).

In step S407, the active power of each generator other than the one targeted for electricity control is calculated using equation (3). The value newly calculated in step S406 is used for the generator terminal voltage _VG , and the value obtained immediately before the power cutoff obtained in step S401 is used for the generator internal voltage _EG . _XG is the generator internal impedance, which is set in the process of transient stability calculation.

In step S408, the generator active power obtained in step S407 is converted into a two-machine model of an unstable group and a stable group.

In step S409, the amount of change in active power during power cut-off in the two-machine model of the unstable group and the stable group is calculated.

In step S410, the sharing ratio of the amount of change in active power during power shedding is determined for the stable group.

In step S411, the active power of the two-machine model of the unstable group and the stable group immediately after power outage is calculated using the sharing ratio determined in step S410.

In step S412, the active power of the two-machine model obtained in step S411 is converted into the active power of the one-machine infinite bus model.

In step S413, the amount of change in active power during power cut-off in the single machine infinite bus model is calculated. This calculated value is saved as the amount of change in active power in one of the generator combinations that can become the first-stage electrical curtailment machine, which was set in step S404.

In step S414, it is determined whether all the generator combinations that can become the first-stage electrical cut-off machine have been calculated. If everything has been calculated, the process ends. If all have not been calculated, the process advances to step S415.

In step S415, the injected current immediately before the power cut is set to return to the state before calculating the amount of change in active power during the power cut, and then the process returns to step S404.

In step S404, the next candidate is set among the generator combinations that can become the first-stage electrical curtailment machine.

From step S405 onwards, the amount of change in active power during power restriction corresponding to the set power restriction target is calculated in the same manner as described above.

Through the above-described iterative processing, the amount of change in active power during electrical shedding in terms of a single machine infinite bus model is calculated for all generator combinations that can become the first-stage electrical shedding machine.

With this method, compared to obtaining similar calculation results using transient stability calculations, it is possible to simulate several hundred milliseconds from the initial state to the occurrence of electrical restriction, and the Y matrix required to simulate electrical restriction. There is no need to recalculate the inverse matrix of .

In addition, in step S410, a complicated method such as calculating the sharing ratio of the amount of change in active power is used, and the active power immediately after power reduction of the unstable group and stable group obtained in step S408 is converted into a one-machine infinite bus model. and not used directly. The reason for this is that the generator active power obtained in step S407 includes an error.

It is correct that the injected current corresponding to the generator subject to power shedding becomes zero after power shedding. Based on this idea, in step S405, the injection current corresponding to the generator to be curtailed is set to zero, but the terminal voltage of the generator to be curtailed, which is included in the node voltage calculated in step S406, is It will not be the value that makes the current zero.

The injection current of the generator is calculated using equation (4). Here, I _G is the injection current, E _G is the generator internal voltage, V _G is the generator terminal voltage, and X _G is the generator internal impedance, all of which are complex numbers.

To calculate the accurate state after shedding, the injection current of the generator to be sheared is increased until _IG in equation (4) is zero, that is, the difference between _EG and _VG is within the allowable range. It is necessary to repeat the processing steps of zeroing and calculating the node voltages.

If the increase in time required to complete the calculation is acceptable, step S405 and step S406, which are the processing steps for calculating the node voltage, are repeated to calculate the accurate state after power cutoff and calculate the accurate generator active power. can also be calculated.

In that case, the processing steps of step S409, step S410, and step S411 are unnecessary, and from the generator active power of the unstable group and stable group obtained in step S408, in step S412, the generator effective power of the one machine infinite bus model is calculated. Just calculate the power.

The additional electricity shedding execution unit 80 uses the measurement information of the generator obtained from the transmission system 10, the constants etc. obtained by the stability evaluation model generation unit 70, and the first stage electricity shedding machine determined by the electricity shedding machine correction unit 50. Based on this, it is determined whether the first stage electrical curtailment machine becomes stable or unstable when it is cut off. The additional electricity shedding execution unit 80 selects an additional electricity shedding machine when the situation becomes unstable, and transmits a control signal for cutting off the target. The difference from the description in Patent Document 3 is that the electrical shedding machine determined by the electrical shedding machine correction unit 50 is the first stage electrical shedding machine.

(effect)
According to the present embodiment, the electricity shedding correction unit 50 allocates the electricity shedding amount to the synchronous generators according to the latest system state, and the first stage electricity shedding selection unit 30 assigns the electricity shedding amount to the renewable energy group. , and if the expected amount of power reduction is insufficient due to a decline in the output of renewable energy, it is possible to clarify the division of roles by having other renewable energy groups compensate for the shortfall. This avoids an excessive increase in the amount of power cutoff that would occur if the power cutter correction mechanism for synchronous generators and the power cutter correction mechanism for renewable energy were simply combined. be able to.

In addition, the stability evaluation model generation unit 70 uses a method that requires less calculation than the transient stability calculation in order to obtain the amount of change in active power during power outage. can be avoided.

Next, the present embodiment will be compared with Patent Documents 1, 2, and 3, and the effects of the present embodiment will be explained.
In Patent Documents 1 and 2, the amount of power reduction can be suppressed, but the ability to respond to unexpected situations is a problem. In Patent Document 3, the amount of electrical restriction is determined in accordance with the actual event, but there is a problem that the amount of electrical restriction is too large.
Specifically, in Patent Documents 1 and 2, the amount of power restriction is increased in advance according to a change in the system state (the content of power restriction is determined in advance). For this reason, there is an advantage that the time from the occurrence of a system fault to power shutoff (power cutoff) is minimized, and the amount of power shutoff can be reduced. Generally speaking, the longer the time from the occurrence of an accident until the power is shut off, the greater the amount of power shutoff required for stabilization. On the other hand, since a regression formula constructed from the results of preliminary calculations (simulations) is used, it is difficult to reflect conditions not assumed in the preliminary calculations or the effects of deviations from assumptions.

On the other hand, Patent Document 3 uses measurement information (generator active power, etc.) after the occurrence of an accident, so it has the advantage of being able to make a determination that is in line with the actual situation. However, calculations necessary for determining stability are performed using measurement information for a certain period of time after the accident occurs, and the necessary amount of electrical control is also determined. Therefore, the power control is slower and the amount of power control is larger than in Patent Documents 1 and 2, in which the content of the power control is determined in advance.

In contrast to the above-mentioned Patent Documents 1, 2, and 3, this embodiment has the advantages of Patent Documents 1, 2, and 3. By increasing the amount of power shedding in response to changes in the state of the power system, it is possible to suppress the increase while also responding to cases where the increase in the amount of power shedding is insufficient due to deviations from assumptions.

According to at least one embodiment described above, the first-stage electrical shedding machine selection section 30, the electrical shedding estimation model generation section 40, the electrical shedding machine correction section 50, the first-stage electrical shedding execution section 60, By having the stability evaluation model generation unit 70 and the additional electricity control execution unit 80, it is possible to maintain a stable state of the power system even if the state of the power system changes significantly.

Although several embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

DESCRIPTION OF SYMBOLS 1... Power system, 2... Bus bar, 3... Power transmission line, 4... Transformer, 5... Generator, 6... Breaker, 10... Transmission system, 11... Information terminal, 12... Control terminal, 20... System stabilization device , 30... First-stage electrical shedding machine selection section, 40... Electrical shedding estimation model generation section, 50... Electric shedding machine correction section, 60... First-stage electrical shedding execution section, 70... Stability evaluation model generation section, 80... Additional electrical control execution unit

Claims (3)

Obtaining system information representing the characteristics of a power system having a generator at a preset period, and using the system information to create a system model that is a simulation model representing a power flow state of power in the power system, Calculate the transient stability when a predetermined system fault occurs in the system model, and cut off the power supply from the generator for each of the predetermined system faults based on the calculation result of the transient stability. a selection unit that selects a first electrical cutoff machine;
Creating a regression equation for predicting a power outage from the system information based on power outage information that is a combination of the power outage information and a first power outage candidate for each of the predetermined system faults in the system model. an electricity control estimation model generation unit that performs
Using the regression equation, the grid information last acquired by the selection unit, and the grid information immediately before the predetermined grid fault occurs, calculate the amount of power reduction necessary to maintain stability of the power grid. , a power shedding machine correction unit that adds a new shelving machine to the first shedding machine or changes the first shedding machine based on the calculated shedding amount;
a first-stage electric control execution unit that transmits a command to cut off the first electric control machine added or changed by the electric control machine correction unit when a system fault occurs;
Model definition information for determining the change in phase angle deviation used to determine the presence or absence of generator step-out from measured values of the power system and generator before and after the occurrence of an accident, and the criteria used to determine the presence or absence of generator step-out. , a stability evaluation model generation unit that prepares from the immediately previous transient stability calculation results;
After an accident occurs, if the generator loses synchronization based on the transition of the phase angle deviation calculated using the model definition information prepared by the stability evaluation model generator and the measured values of the power system, and the judgment criteria, an additional power control execution unit that selects and cuts off an additional power control machine when the determination is made;
Equipped with
Grid stabilizer. The electrical control machine correction section
Based on the regression formula and the system information immediately before the predetermined system fault occurs, the amount of power reduction (A) required to maintain stability of the power system is calculated, and based on the regression formula and the selection unit, Based on the last acquired grid information, the amount of power shedding (B) necessary to maintain stability of the power system is calculated, and the magnitude relationship and difference between the amount of power shedding (A) and the amount of power shedding (B) are calculated. a power control synchronous machine determining unit that selects a power control machine to be added to or changed from the first power control machine based on the synchronous generator;
From the regression equation and the system information immediately before the predetermined system fault occurs, the amount of power shedding necessary to maintain stability of the power system is calculated, and the shortage of the amount of power shedding due to the decrease in the output of the first power shedding machine is calculated. and a power reduction renewable energy determining unit that selects a power reduction device for renewable energy power sources to be added to the first power reduction device based on the power reduction amount calculated by the regression formula;
Equipped with
The system stabilizing device according to claim 1. The stability evaluation model generation unit includes:
Based on the transient stability calculation results, the generators in the power system are divided into unstable generator groups and stable generator groups, and the definition information of an unstable generator group model is obtained by converting the unstable generator group into one generator. Unstable generator model formulation department that compiles,
A stable generator model that summarizes the definition information of a function that calculates the total active power of stable generators in the external system and a stable generator group model that converts a stable generator group into one generator from the transient stability calculation results. Planning department and
a criterion formulation unit that creates a criterion for phase angle deviation used for stability determination from the transient stability calculation results;
Using the information obtained in the process of transient stability calculations and immediately before power shedding necessary for system calculations, we can create a one-machine infinite bus model that occurs when the first power shedding machine is cut off, without performing transient stability calculations. an output change model formulation unit that calculates the converted effective power change amount for all combinations that can become the first curtailment machine;
Equipped with
The system stabilizing device according to claim 1 or claim 2.

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