Renewable energy system stabilization system and system stabilization support method

Abstract

A system for stabilizing a renewable energy system (10) that supports the operation of a power system connecting a load and a first power source, including a thermal power generator (301-1, 301-2, 301-3) that generates electricity using at least thermal energy, and / or a second power source, including a renewable energy device (300) that generates electricity using renewable energy, the system comprising: An operating limit control unit (15) that controls an operating limit with respect to the total power of system devices, and a determination unit (16) that calculates a power flow state for each time set in the future of the power supply system based on load distribution information, including a power generation plan value of the first power source, a predicted value of the output power of the second power source, and a predicted value of the power demand in the power supply system, and determines whether each calculated power flow state is stable by comparing each calculated power flow state with the operating limit value, characterized in that the determination unit (16) sequentially changes the first output power of the first power source defined by the power generation plan value of the first power source, calculates each of the power flow states based on the power, including the changed first output power, and the predicted value of the output power of the second power source, and outputs the result of the calculation to the operation limit control unit (15), and if a positive determination result is obtained from the determination unit (16), the operating limit control unit (15) controls the operating limit at each time specified in the future as the sum of the changed first output power and the predicted value of the output power of the second power source added to the changed first output power.

Description

Technical FieldThe present invention relates to a renewable energy system stabilization system and a system stabilization support method for supporting the stabilization of a power supply system using renewable energy.Background ArtIn an example of control in a system for stabilizing a power supply system, in order to suppress fluctuations in the state of the electric system occurring in a power supply system, a necessary number of generators are turned off (referred to as generator shedding) to temporarily stabilize the power supply system or prevent overloading of a transmission line or a transformer in the event of a fault on a transmission line or the like. In another example of the control, a required amount of load is discharged (referred to as load discharge) to suppress variations of the power supply system upon a frequency drop of the power supply system. If the control for suppressing the fluctuations of the system state is executed, adjustment must be made according to the state of the power supply system.Here, there is a method of predicting fluctuations of a system state that may occur in a power supply system, setting in advance the content of the fluctuation suppression control according to the prediction result, and executing the predetermined control in the case of fluctuations. For example, as described in NPL 1 ("Development of Transient Stability Controller System (TSC) Based on On-Line Stability Calculation"), there is a system in which a required number of generators are turned off so that the short-term stability of the system is maintained, for example, in a malfunction of a transmission line.This system employs a configuration in which a system state is periodically detected, a short-term stability calculation is performed in advance with respect to a plurality of presumed failure cases to obtain a required number of dropped generators, and the obtained content is recorded in a control table and updated to prepare for an actual failure. Then, in the case of an actual malfunction, this system searches the previously obtained dropped generators for one corresponding to the malfunction and turns off the found generator to stabilize the power supply system.In recent years, a large number of renewable energy devices such as wind turbines and photovoltaic power generation devices have been introduced. At this time, when the power generated by the renewable energy device is supplied to an existing power supply system, the power flowing through system devices such as a transmission line and a transformer largely fluctuates, which may result in an overload problem in a normal case, a stability maintenance problem in the event of occurrence of a fault, or the like. In order to solve these problems, it is known to control a renewable energy device and a generator for maintaining stability, as disclosed in JP 2015-130 777 A (PTL 1).Document US 2017 / 0 145 925 A1 discloses a system for stabilizing a renewable energy system according to the preamble of claim 1.Citation ListPatent LiteraturePTL 1: JP 2015-130 777 ANon-Patent LiteratureNPL 1: Journal of the Institute of Electrical Engineers of Japan, Vol. 115-B, No. 1 (January 1995 )Summary of the InventionTechnical ProblemThe output of a renewable energy device such as a photovoltaic power generation device and a wind turbine fluctuates greatly in a short term. Accordingly, a monitoring control and data acquisition / power control system, which is a typical example of a load distribution monitoring and control system for monitoring and controlling the power and voltage of a power supply system, constantly monitors the current flowing through transmission devices every few seconds. When an operator determines that the current flowing through the transmission apparatuses may exceed the operation limit value of the transmission apparatuses (limit value determined by a thermal limit or the like), he performs an operation of adjusting the output of the generators at both ends of the apparatuses that may be overloaded (generator replacement), and an output suppression command is issued to the renewable energy device and the generator to eliminate the overload. However, if the system devices constitute a loop-shaped large-scale power supply system, suppression of output power is applied to a plurality of generators, so that an operator cannot work in an attempt and error to calculate an appropriate congestion elimination amount.In addition, a generator is subject to vibration in a system failure due to lightning strike or the like for about 10 seconds, and in NPL 1, a stabilization countermeasure system for stopping a generator in an emergency to maintain the short-term stability of such a generator is known. Because the consumption of renewable energy devices in power supply systems greatly increases and the output power of renewable energy devices usually greatly fluctuates rapidly, a short-term shift other than a shift in an assumed fault may occur in a power supply system and a previously assumed stabilization measure may become improper.In this regard, calculations performed in advance in a system stabilization system may require post-calculation and post-correction after occurrence of a system fault to perform control with a certain time delay and certain margins for the strength of control. However, when a large number of renewable energy devices are operated, their output power fluctuates greatly in a short term, so that post-calculation and post-correction may also become inappropriate.In addition, unlike general generators, renewable energy devices are operated at a constant power factor in most cases, and reactive power supplied to or absorbed by the power supply system in a short time is not large, so that the voltage of the system devices is likely to fluctuate. For example, in the case of a stopped generator, a decrease in the frequency of the power supply system occurs, so that the demand load corresponding to the output of the stopped generator is output urgent. However, under the condition that the voltage of the power supply system rises at this time, the load of the power supply system becomes high, and there then results insufficient strength of control and a significant decrease in the power supply frequency without adding a voltage correction to the load shedding amount. Therefore, many generators in the power supply system can be stopped one after another, resulting in a failure (so-called blackout) concerning the entire power supply system.An object of the present invention is to change a system device operation limit value according to the power flow state of a power supply system even with an increase in power from a renewable energy device connected to the power supply system.Solution of the ProblemTo achieve the above object, the present invention provides a system for assisting the operation of a power supply system that connects a load and a first power source including a heat generator that generates electricity using at least heat energy and / or a second power source including a renewable energy device that generates electricity with renewable energy, the system including: an operation limit control unit that controls an operation limit with respect to the total power of system devices; and a determination unit that determines a power flow state for each future set time of the power supply system based on load distribution information including a power generation schedule value of the first power source, a predicted value of the output power of the second power source, and a predicted value of the power demand in the power supply system, calculated and determines whether each calculated power flow state is stable by comparing each calculated power flow state with the operation threshold, wherein the determination unit sequentially changes the first output power of the first power source defined by the power generation map value of the first power source, calculates each of the power flow states based on the power including the changed first output power and the predicted value of the output power of the second power source, and outputs the result of the calculation to the operation threshold control unit, and if a positive determination result is obtained from the determination unit, the operation threshold control unit controls the operation threshold at each time set in the future as a sum of the changed first output power and the predicted value of the output power of the second power source added to the changed first output power.Advantageous Effects of the InventionAccording to the present invention, a system device operation limit value can be changed according to the power flow state of a power supply system even with an increase in power from a renewable energy device connected to the power supply system.The other effects of the present invention will be described herein.Brief Description of the DrawingsThe following are shown: FIG. 1 is an overall configuration diagram of a system for a power supply system according to an example of the present invention, FIG. 2 is a configuration diagram for describing a specific configuration of a renewable energy system stabilization system according to an example of the present invention, FIG. 3 is an explanatory diagram for describing the relationship between an operation limit value and the total output power according to an example of the present invention, FIG. 4 is an explanatory diagram showing an example of power generation plan generation processing after incorporation of a non-fixed power source according to an example of the present invention, FIG. 5A is a characteristic diagram of a limiting power flow, FIG. 5B is a characteristic diagram of an annual load duration curve, FIG. 6 is a flowchart for describing processing of an assumed disturbance stabilization calculation unit according to an example of the present invention, FIG. 7A is a characteristic diagram of the phase angle of a generator, FIG. 7B is a characteristic diagram of the terminal voltage of the generator, FIG. 7C is a characteristic diagram of the total output power; and FIG. 7D is a characteristic diagram showing the frequency of a transmission line.DESCRIPTION OF EMBODIMENTSHereinafter, examples of the present invention will be described with reference to the drawings.FIG. 1 is an overall configuration diagram of a system for a power supply system according to an example of the present invention. In FIG. 1, a system 1 for a power supply system is for controlling a power supply system connecting a power source and a load, for example, a system constituted by transmission lines 100 and 101, a bus 102, etc., and includes a renewable energy system stabilization system 10, a load distribution control system (load distribution monitoring control system) 20, and a device 30 for executing countermeasures against failures. Here, the renewable energy system stabilization system 10 is capable of transmitting and receiving information to and from the load distribution control system 20 and the disturbance countermeasure execution device 30 in a wired or wireless manner. Note that energy that is renewable may be referred to as renewable energy in the following description.Thermal force generators (first power sources) 301- 1, 301- 2, and 301- 3 that generate electricity using thermal energy are connected to the transmission line 100. Here, the heat force generators 301- 1 and 301- 2 are connected to an end portion of the loop-shaped transmission line 100, and a renewable energy device (second power source) 300 that generates electricity using offshore wind power is connected to the end portion of the transmission line 100. The transmission line 101 branched from the transmission line 100 is connected to the bus 102. Loads 400- 1 and 400- 2 are connected to the bus 102.The load distribution control system 20 operates the power supply system, and is composed of, for example, a computer device including a central processing unit (CPU), an input device, an output device, a communication device, and a storage device. Here, the load distribution control system 20 monitors the state of the power supply system based on a value measured by system apparatuses (not shown) including various measurement instruments that measure voltage, current, and power of the power supply system, generates load distribution information including a power generation schedule value related to the respective thermal force generators 301- 1, 301- 2, and 301- 3, a renewable energy output prediction value related to the renewable energy device 300, and a demand prediction value in the power supply system, and transmits the generated load distribution information 500 to the renewable energy system stabilization system 10. Note that the load distribution control system 20 is also capable of transmitting system configuration data generated based on values measured by various measurement instruments (including a voltmeter, a current meter, and a power meter) as online information about the power supply system to the renewable energy system stabilization system 10 in addition to the load distribution information 500.The renewable energy system stabilization system 10 generates a system device operation threshold, which is an operation threshold (operation target value), when the load distribution control system 20 operates the power supply system, based on the load distribution information 500 received from the load distribution control system 20, and sends operation threshold information 510 including the generated operation threshold to the load distribution control system 20.In addition, the renewable energy system stabilization system 10 generates a renewable energy output suppressing amount for reducing the output of the renewable energy device 300 based on the load distribution information 500 received from the load distribution control system 20, and sends renewable energy output suppressing amount information 520 to the load distribution control system 20, The information is recorded in a countermeasure control table (not shown), and transmits the information recorded in the countermeasure control table as countermeasure control information 530 to the countermeasure execution apparatus 30. In addition, the renewable energy system stabilization system 10 generates recovery support information about a power system recovery countermeasure based on the load distribution information 500 received from the load distribution control system 20, and transmits the generated recovery support information 540 to the load distribution control system 20.The interference countermeasure execution device 30 is constituted by, for example, a computer device including a CPU, an input device, an output device, a communication device, and a storage device. Here, the CPU functions as a control command unit that sends and receives information about the communication device to and from the renewable energy system stabilization system 10, records the countermeasure control information 530 received from the renewable energy system stabilization system 10 in the storage device, generates a control command for executing a disturbance countermeasure based on the countermeasure control information 530 recorded in the storage device, and outputs the generated control command to the control execution units 32- 1 and 32- 2. The control execution units 32- 1 and 32- 2 control the system devices located on the transmission lines 100 and 101 and the bus 102, and treat the renewable energy device 300 as a control object. Examples of the system devices include a switch (connecting or disconnecting a capacitor or a coil to or from the transmission line 100, for example), a switchgear, a load switch, a voltage regulator (tap position adjustment type transformer with adjustable tap position), and a protection relay, which are not illustrated.In addition, a fault detection unit (fault detector) 31 that detects a system fault 200 on the transmission line 100 and a voltage detection unit (voltmeter) 33 that detects the voltage of the bus 102 are arranged as system devices. Here, in the case of a system fault 200 on the transmission line 100, the system fault 200 is detected by the fault detection unit 31, and the detection result is transmitted from the fault detection unit 31 to the fault countermeasure execution apparatus 30. In addition, the voltage of the bus 102 is detected by the voltage detection unit 33, and the detection result is transmitted from the voltage detection unit 33 to the interference countermeasure execution apparatus 30 via the control execution unit 32-2.The interference countermeasure execution device 30 generates a control command based on the countermeasure control information 530, and outputs the generated control command to the control execution units 32- 1 and 32- 2. For example, the device 30 for executing countermeasures against failures in the case of a system failure 200 on the transmission line 100 based on the detection result of the failure detection unit 31 refers to the countermeasure control information 530, generates a control command for emergency stop of the renewable energy device 300 based on the countermeasure control information 530, and outputs the generated control command to the control execution unit 32- 1. In this case, the control execution unit 32- 1 executes control for emergency stop of the renewable energy device 300 according to the control command with respect to the renewable energy device 300.In addition, if it is necessary to reduce the output of the renewable energy device 300, the device 30 for executing countermeasures against disturbances generates a control command for reducing the output of the renewable energy device 300 based on the countermeasure control information 530, and outputs the generated control command to the control execution unit 32- 1. In this case, the control execution unit 32- 1 executes the control for suppressing the output of the renewable energy device 300 according to the control command with respect to the renewable energy device 300.Further, if it is necessary to discharge the load 400- 1 connected to the bus 102 from the bus 102, the fault countermeasure execution device 30 generates a control command for discharging the load 400- 1 from the bus 102 on the basis of the countermeasure control information 530, and outputs the generated control command to the control execution unit 32- 2. In this case, the control execution unit 32- 2 executes a load switch off control according to the control command with respect to the load switch (not illustrated) located between the bus 102 and the load 400- 1.FIG. 2 is a configuration diagram for describing a specific configuration of the renewable energy system stabilization system according to an example of the present invention. In FIG. 2, the renewable energy system stabilization system 10 is comprised of, for example, a computer device including a CPU, an input device, an output device, a communication device, and a storage device.The CPU is designed as a central processing unit which comprehensively controls the operation of the overall system. The input device is composed of a keyboard or a mouse, and the output device is composed of a display or a printer. In addition, the communication device includes a network interface card (NIC) for connecting to a wireless LAN or a wired LAN. Further, the storage device is composed of a storage medium such as a random access memory (RAM) and a read only memory (ROM).The storage device stores various computer programs executed by the CPU and a database processed by the CPU and storing various kinds of data. For example, the storage device stores a system configuration generation program acting as the system configuration generation unit 11, a future total power cross-section calculation program acting as the future total power cross-section calculation unit 12, a general calculation program acting as the general calculation unit 13, a database acting as the system data storage unit 14, and an operation limit calculation program acting as the operation limit calculation unit 15, each of which is a program or a database belonging to a normal countermeasure unit 10 a. In addition, the storage device stores an assumed disturbance stabilization calculation program acting as the assumed disturbance stabilization calculation unit 16 and a disturbance recovery calculation program acting as the disturbance recovery calculation unit 17, these programs belonging to a disturbance countermeasure unit 10b.The system data storage unit 14 stores data on the power generation plan value, the demand prediction value, and the renewable energy output prediction value that are associated with the load distribution information 500 transmitted from the load distribution control system 20. The above-mentioned data refers to, for example, each predetermined time in the future based on the time of data collection, planning, or prediction value calculation, and refers to every preceding 15 minutes to 24 hours.The system configuration generation unit 11 acquires online information on the state of the system device connection (for example, switch on-off state and switchgear on-off state) and the state of the power supply system from the system devices (switches, switchgear, load switches, protection relays, voltmeter, ammeter, and power meter) connected to the power supply system, generates a system model according to the connection state of the system devices, and generates system configuration data indicating the system configuration (the configuration of the power supply system) based on the generated system model. For example, a system model indicating, for example, load, transmission line, and system device connection states is generated with respect to the transmission line 100 connected to the thermal force generators 301- 1 and 301- 2. The system configuration generation unit 11 transmits the system configuration data obtained from the generated system model to the future power flow area calculation unit 12, and stores the system configuration data in the system data storage unit 14.The future power flow area calculation unit 12 calculates the active power and the reactive power flowing in the power supply system and the voltage of the system devices based on the system configuration data by a calculation method called power flow calculation, and outputs the result of the calculation to the general calculation unit 13. Here, for example, the future power flow area calculation unit 12 acquires information indicating a future power flow area every 15 minutes to every 24 hours before, based on the time of data collection or calculation (information indicating the future power flow state), which is information on the active power and reactive power flowing in the power supply system and the system device voltage.When the operation threshold information 510 about an operation threshold determined by an operator is received from the load distribution control system 20, the operation threshold calculation unit 15 calculates the latest operation threshold based on the operation threshold associated with the received operation threshold information 510 and an operation threshold indicating the result of the short-term stability calculation with respect to an assumed fault, which is a calculation result of the assumed fault stabilization calculation unit 16, transmits the calculated latest operation threshold to the general calculation unit 13, and transmits information about the latest operation threshold as the operation threshold information 510 to the load distribution control system 20.When the system devices are operated using the latest operation threshold based on the calculation result of the future power flow area calculation unit 12 and the latest operation threshold calculated by the operation threshold calculation unit 15, the general calculation unit 13 determines whether the power supply system is stable with respect to the cross section of the power flow for each specified future time (for example, power flow state for every 15 minutes to 24 hours ahead). For example, the general calculation unit 13 determines whether the power supply system will be overloaded in a case where the system devices are operated using the latest operation threshold, and if it is determined that the power supply system will be overloaded (becoming unstable), the general calculation unit 13 performs calculation for reducing the output of the renewable energy device 300, reducing the output of the thermal force generators 301- 1 and 301- 2, or performing an increase in the output. Then, for example, the general calculation unit 13 transmits the renewable energy output suppression amount information 520 indicating the renewable energy output suppression amount with respect to the renewable energy device 300 to the load distribution control system 20 as a result of its calculation.In addition, if it is determined that the power supply system is overloaded and unstable (negative determination result), the general calculation unit 13 also functions as an output setting information generation unit for generating output setting information for setting the output power (first output power) of the thermal power generators 301- 1, 301- 2, and 301- 3 (first power sources) and / or the output power (second output power) of the renewable energy device 300 (second power source). Here, the general calculation unit 13 is capable of adding the output setting information to the renewable energy output suppression amount information 520 and transmitting the information to the load distribution control system 20.Here, when the output of the renewable energy device 300 is increased in a certain range in a normal case, a generator (thermal power generator) is operated in the reduced output range or the generator is stopped so that the total output of the power supply system becomes equal to or lower than the operation limit value of the transmission apparatuses. However, a decrease in the number of generators connected to the power supply system results in a decrease in frequency adjustment capability in the power supply system, so that a considerable frequency disturbance may result as the demand of the power supply system varies.In consideration of such a problem, the general calculation unit 13 performs calculation for adjusting the amount of output power of the generator, calculates an amount for suppressing output of renewable energy by comparing the calculation result with an operation threshold, and transmits the renewable energy output suppression amount information 520 including the calculated renewable energy output suppression amount to the load distribution control system 20.The assumed disturbance stabilization calculation unit 16 acquires information including the power generation schedule value of the first power source, a predicted value of the output power of the second power source, and a predicted value of the power demand in the power supply system, and repeatedly performs time axis simulation processing called short-term stability calculation with respect to hundreds of predetermined assumed disturbance cases based on the acquired information. If instability is the result of the time axis simulation processing, the presumed disturbance stabilization calculation unit 16 determines whether the power supply system becomes stable by implementing a countermeasure such as generator shedding and load shedding. If stability is determined, the presumed disturbance stabilization calculation unit 16 records information on the amount of control such as generator and load shedding in the countermeasure control table (not shown), and sends the information recorded in the countermeasure control table as countermeasure control information 530 to the disturbance countermeasure execution apparatus 30.If the result of the short-term stability calculation is "stable", the presumed disturbance stabilization calculation unit 16 further increases the operation limit value, increases the presumed transmission power, and repeatedly executes the time axis simulation processing of hundreds of presumed disturbance cases. Here, the assumed disturbance stabilization calculation unit 16 sequentially determines whether the result of the time axis simulation processing becomes "unstable" in the process of sequentially increasing the operation limit value, and transmits each determination result to the operation limit value calculation unit 15. If the determination result "unstable" after the determination result "stable" is obtained from the assumed disturbance stabilization calculation unit 16, the operation limit value calculation unit 15 registers the increased operation limit value when the determination result "stable" is finally obtained as a new operation limit value, and transmits the operation limit value information 510 including the registered operation limit value to the load distribution control system 20.The failure recovery calculation unit 17 generates recovery support information for returning the state of the power supply system to a pre-failure state based on the system state after the execution of the presumed failure stabilization countermeasure determined by the calculation of the presumed failure stabilization calculation unit 16, examples of which include the state of the power supply system after implementation of generator shedding or load shedding by a stabilization countermeasure, and transmits the generated recovery support information 540 to the load distribution control system 20.Upon receiving the operation limit information 510 including the new operation limit, the load distribution control system 20 notifies the owner of the renewable energy device 300 of the operation limit information 510 including the new operation limit, or discloses the content of the operation limit information 510 of the home page or the like. By viewing the disclosed content of the operating threshold information 510, the owner of the renewable energy device 300 may use information about the new operating threshold in offering for a next day transaction or a subsequent transaction on a power generation market. Thereby, the risk of missing power generation opportunities because congestion of a transmission line obstructs the renewable energy device 300 can be reduced.FIG. 3 is an explanatory diagram for describing the relationship between the operation limit value and the total output power according to an example of the present invention. In FIG. 3, month and day are plotted on the horizontal axis and the power flow (MW) is plotted on the vertical axis. The total output power (P1+P2) in the power supply system may vary widely from day to day as indicated by curve X. Here, in a case where an operation threshold (the first operation threshold) is L 1 before the renewable energy device 300 is connected to the power supply system, for example, 13000 (MW), the operation threshold L 1 is different from the actual total output power (P 1+P 2), and this difference is the available capacity. The available capacity is an amount (power amount) that can be output from the renewable energy device 300 connected to the power supply system as a "non-fixedly connected" power source. Here, the "non-hardwired" current source means a current source that is connected under an output power suppression agreement when no capacitance is available.Accordingly, under the condition that the operation limit value can be increased from L 1=13000 (MW) to L 2=1700 (MW), for example, the power that can be output from the renewable energy device 300 to the power supply system (outputable amount), the sum of a renewable energy output increment ΔP 1 corresponding to the difference between the operation limit value L 1 and the total output power (P 1+P 2), and a renewable energy output increment ΔP 2 corresponding to the difference between the operation limit value L 2 and the operation limit value L 1 is. When the renewable energy device 300 is capable of generating power of an amount resulting from the renewable energy output increment ΔP 1 plus the renewable energy output increment ΔP 2, and the generated power can flow via the transmission line 100, for example, the generation of electric power by the thermal force generator 301- 1 and the thermal force generator 301- 2 can be reduced, and therefore the generation of CO 2 due to the power generation by the thermal force generator 301- 1 and the thermal force generator 301- 2 can be reduced. Note that the operation threshold L 2 is a second operation threshold that is applied to the power supply system and the power supply devices after the renewable energy device 300 is connected to the power supply system.FIG. 4 is a diagram for explaining an example of power generation plan generation processing after incorporation of the non-fixedly connected power source according to an example of the present invention. In Fig. 4, data is exchanged between a general electricity transmission and distribution store operator 50 and an electricity generation store operator 52. In this case, a spot market 54 is prepared on the day before the preceding day, a pre-hour market 56 is prepared from the preceding day to the current day, and a bid 58 with respect to the spot market 54 and bids 60 and 62 with respect to the pre-hour market 56 are possible. On the previous day, the power generation shop operator 52 generates a next day power generation plan at time t 1 and transmits information on the generated next day power generation plan at time t 2 to the general power transmission and distribution shop operator 50. In response, the general power transmission and distribution business operator 50 predicts the power demand for the next day, formulates a power generation plan for the next day, and predicts (judges) whether the transmission apparatuses are overloaded (clogged) based on the power demand prediction result and the power generation plan formulation result. If it is predicted that the transmission apparatuses are overloaded, the general power transmission and distribution store operator 50 calculates the amount of suppression required to eliminate the overload, and discloses information on the calculated amount of suppression to the power generation store operator 52 on the homepage or the like at time t3. Then, the operator 52 of a power generation shop checks the power generation plan for the next day at time t 4 based on the disclosed information.Also, the current day generation shop operator 52 generates a current day generation plan at time t 5 up to 1+α hours (several hours) before the actual supply and demand cross section, and transmits information on the generated current day generation plan to the general power transmission and distribution shop operator 50 at time t 6. In response, the general power transmission and distribution business operator 50 predicts the power demand for the current day, formulates a power generation plan for the current day, and predicts (judges) whether the transmission apparatuses are overloaded (clogged) based on the power demand prediction result and the power generation plan formulation result. If it is predicted that the transmission apparatuses are overloaded, the general power transmission and distribution store operator 50 calculates the amount of suppression required to eliminate the overload, and discloses information on the calculated amount of suppression to the power generation store operator 52 on the homepage or the like at time t 7. The operator 52 of a power generation store checks the power generation plan for the current day at time t 8 based on the disclosed information.Further, the same processing is repeated up to 1 hour before the current supply and demand cross section. In other words, the power generation store operator 52 generates the immediately preceding power generation plan at time t 9, and transmits information on the generated immediately preceding power generation plan to the general power transmission and distribution store operator 50 at time t 10. In response, the general power transmission and distribution business operator 50 predicts the immediately preceding power demand, formulates the immediately preceding power generation plan, and predicts (judges) whether the transmission apparatuses are overloaded (clogged) based on the power demand prediction result and the power generation plan formulation result. If it is predicted that the transmission apparatuses are overloaded, the general power transmission and distribution store operator 50 calculates the amount of suppression required to eliminate the overload, and discloses information on the calculated amount of suppression to the power generation store operator 52 on the homepage or the like at time t11. The operator 52 of a power generation store views the immediately preceding power generation plan at time t 12 based on the disclosed information.As described above, a series of processing becomes complicated in the case of transmission equipment overload (congestion). However, if it is determined that no overload should occur by increasing the operation threshold from the operation threshold L 1 to the operation threshold L 2 as illustrated in FIG. 3, both the general power transmission and distribution store operator 50 and the power generation store operator 52 are relieved of the problem of power generation suppression due to clogging and the work for determining a power generation plan is reduced.FIGS. 5A and 5B are characteristic diagrams showing the state of the power supply system according to an example of the present invention. FIG. 5A is a characteristic diagram of a luster power flow, and FIG. 5B is a characteristic diagram of an annual load duration curve. In FIG. 5A, month and day are plotted on the horizontal axis, and the power flow (MW) is plotted on the vertical axis. In FIG. 5B, time is plotted on the horizontal axis and power flow (MW) is plotted on the vertical axis. In FIGS. 5A and 5B, the actual power flow in the power supply system (total power P 1+P 2) is almost the operation limit value L 1=13000 (MW)=13.0 (GW) or less, as indicated by the curve X 1, but largely varies from month to month. In addition, when an increase in power demand in the power supply system is assumed, the assumed power flow (total power P 1+P 2) often almost exceeds the operation limit value L 1=13000 (MW)=13.0 (GW) as indicated by the curve X 2, and greatly fluctuates from month to month.Here, the output power of the renewable energy device 300 is suppressed if the actual power flow (total power P 1+P 2) exceeds the operation limit value L 1. For example, if the actual power flow (total power P 1+P 2) exceeds the operation limit value L 1=13.0 GW, the output power of the renewable energy device 300 needs to be suppressed for 5760 hours (time when the curve X 2 and the operation limit value L 1=13.0 GW intersect each other) of 8760 hours (one year) as indicated by the curve X 2.On the other hand, under the condition that a countermeasure can be taken according to the calculation result of the assumed disturbance stabilization calculation unit 16 and the operation limit value is increased from the operation limit value L 1 to the operation limit value L 2=117.0 GW, the time during which the output of the renewable energy device 300 is suppressed can be reduced to about 1000 hours, so that the fuel cost of, for example, the thermal force generators 301- 1 and 301- 2 can be greatly reduced. In this example, the fuel cost reduction amount of the thermal force generators 301- 1 and 301- 2 is about 5.4 TWh, so that when the fuel cost is 10 yen / kWh, an annual fuel cost reduction of about 54 billion yen can be expected, and it can be said that the economic effect is remarkable. In addition, as indicated by the arrow Y, the time of congestion of the transmission line can be reduced as the power demand in the power supply system increases.FIG. 6 is a flowchart for describing the processing of the assumed disturbance stabilization calculation unit according to an example of the present invention. In FIG. 6, the assumed disturbance stabilization calculation unit 16 starts processing by accessing a database (not shown) to be managed or to be accessed. At this time, data on the power generation schedule value (power generation schedule value of the heat power generator), the demand prediction value (predicted value of power demand in the power generation system), and the renewable energy output prediction value (predicted value of output power of the renewable energy device 300) are stored in the database, examples of which include data for each time set in the future, which is data on a cross section for every 15 minutes to every 24 hours ahead.The presumed disturbance stabilization calculation unit 16 refers to the data stored in the database first, sets system cross-sectional data at the judgment time based on the referred data (S 201), and generates data on a presumed power flow cross-section by a calculation method called power flow calculation based on the set system cross-sectional data (S 202).Next, the assumed disturbance stabilization calculation unit 16 sets an assumed disturbance condition (S 203). For example, the presumed fault stabilization calculation unit 16 sets various system faults such as N-1 (fault in which one plant is stopped from normal operation), N-2 (fault in which two plants are simultaneously stopped from normal operation), or N-1-1 (fault in which one plant is stopped from normal operation and another plant is stopped during continuation of stopping).Next, the assumed disturbance stabilization calculation unit 16 performs short-term stability countermeasure calculation by a method called short-term stability calculation, which is, for example, a method of obtaining dynamic motion for about 10 seconds in the case of system disturbance (S 204). If the calculation result thereby obtained is that the system becomes unstable (synchronous generator operation is lost), the presumed disturbance stabilization calculation unit 16 performs calculation for stabilizing the system by suppressing the generator output, records the calculation result in the countermeasure control table, and transmits the information recorded in the countermeasure control table as countermeasure control information 530 to the disturbance countermeasure execution apparatus 30. At the same time, the presumed malfunction stabilization calculation unit 16 performs calculation for stabilizing the power supply system by suppressing the output of renewable energy (the output of the renewable energy device 300), records the calculation result in the countermeasure control table, and transmits the information recorded in the countermeasure control table as countermeasure control information 530 to the malfunction countermeasure execution device 30.If the interference countermeasure execution device 30 receives the countermeasure control information 530, the interference countermeasure execution device 30 executes generator output suppression processing and renewable energy output suppression processing based on the received countermeasure control information 530. If the interference countermeasure execution device 30 executes the generator output suppression processing, the interference countermeasure execution device 30 generates, for example, an output suppression control command of the thermal force generators 301- 1 and 301- 2, and outputs the generated control command to the control execution unit that controls the thermal force generators 301- 1 and 301- 2. The output power of the thermal force generators 301- 1 and 301- 2 is suppressed by the control of the control execution unit, and the total output power flowing through the transmission line 100 and the transformer then decreases.In addition, the apparatus 30 for executing countermeasures against disturbances, if executing the renewable energy output suppressing processing, generates a control command for suppressing the output of the renewable energy apparatus 300 or a control command for emergency stop of the renewable energy apparatus 300 and outputs the generated control command to the control execution unit 32- 1. When the control execution unit 32- 1 executes the control for suppressing the output of the renewable energy device 300 according to the control command, the output of the renewable energy device 300 is suppressed. In addition, when the control execution unit 32- 1 executes the control for an emergency stop of the renewable energy device 300, the renewable energy device 300 executes an emergency stop in, for example, about 0.2 s (seconds).Next, the presumed disturbance stabilization calculation unit 16 determines whether there is a significant change in the system voltage from the result of the short-term stability calculation in step S 204, and performs a voltage maintenance calculation if it is determined that the system voltage deviates from a predetermined range (S 205). At this time, the presumed disturbance stabilization calculation unit 16 performs voltage maintenance calculation for maintaining the system voltage within a specified range by phase adjustment device control, records the calculation result in the countermeasure control table, and transmits the information recorded in the countermeasure control table as countermeasure control information 530 to the disturbance countermeasure execution apparatus 30. In this case, voltage maintenance information consisting of generator output setting information for setting the first output power (third information), and load shedding information for shedding the load of the power supply system (fourth information) is recorded in the countermeasure control table as countermeasure control information 530.If the interference countermeasure execution device 30 executes the phase adjustment device control based on the received countermeasure control information 530, the interference countermeasure execution device 30 generates a control command for maintaining the system voltage within a specified range by the phase adjustment device control, and outputs the generated control command to the control execution unit (not illustrated) that controls the phase adjustment devices. For example, when the control execution unit turns on a switch for connecting a capacitor or a coil to the transmission line 100, the capacitor or the coil is connected to the transmission line 100. The voltage of the transmission line 100 increases when the capacitor is connected to the transmission line 100, and the voltage of the transmission line 100 decreases when the coil is connected to the transmission line 100. Thereby, the voltage of the power supply system is maintained within a specified range.In addition, if the interference countermeasure execution device 30 executes transformer tap setting processing based on the received countermeasure control information 530, it generates a control command for keeping the system voltage within a range specified by the transformer tap setting processing, and outputs the generated control command to the control execution unit that executes the transformer tap setting processing. For example, when the control execution unit adjusts the tap position of the tap position adjustment transformer, the ratio between the input voltage and the output voltage of the tap position adjustment transformer and the output voltage of the tap position adjustment transformer change according to the tap position. Thereby, the voltage of the transmission line having the tap position adjusting transformer is maintained within a specified range.Further, if the apparatus 30 for executing countermeasure against noise executes generator output adjustment processing based on the received countermeasure control information 530, it generates, for example, a control command for adjusting the output of the thermal force generators 301- 1 and 301- 2, and outputs the generated control command to the control execution unit that controls the thermal force generators 301- 1 and 301- 2. The output power of the thermal force generators 301- 1 and 301- 2 is adjusted by the control of the control execution unit, and the voltage of the power supply system is then kept within a specified range.In addition, if the countermeasure execution device 30 executes load shedding processing based on the received countermeasure control information 530, it generates, for example, a control command for shedding the load 400- 1, and outputs the generated control command to the control execution unit 32- 2. When the load 400- 1 is dropped by the control execution unit 32- 2, the voltage of the bus 102 to which the load 400- 1 is connected is maintained within a specified range.Next, the presumed disturbance stabilization calculation unit 16 performs overload countermeasure calculation if it is determined that the power flowing through the transmission line or the transformer exceeds a predetermined amount (S 206). At this time, the presumed disturbance stabilization calculation unit 16 performs overload countermeasure calculation for stabilizing the system by suppressing the generator output, records the calculation result in the countermeasure control table, and transmits the information recorded in the countermeasure control table as countermeasure control information 530 to the disturbance countermeasure execution apparatus 30. At the same time, the presumed disturbance stabilization calculation unit 16 performs overload countermeasure calculation for stabilizing the system by suppressing the output of renewable energy, records the calculation result in the countermeasure control table, and transmits the information recorded in the countermeasure control table as countermeasure control information 530 to the disturbance countermeasure execution apparatus 30.The interference countermeasure execution device 30 executes generator output suppression processing and renewable energy output suppression processing based on the received countermeasure control information 530. If the interference countermeasure execution device 30 executes the generator output suppression processing, the interference countermeasure execution device 30 generates, for example, an output suppression control command of the thermal force generators 301- 1 and 301- 2, and outputs the generated control command to the control execution unit that controls the thermal force generators 301- 1 and 301- 2. The output power of the thermal force generators 301- 1 and 301- 2 is suppressed by the control of the control execution unit, and the total output power flowing through the transmission line 100 and the transformer then decreases. This can prevent the power flowing through the transmission line or the transformer from exceeding a predetermined amount so as to cause overload.In addition, if executing the renewable energy output suppressing processing based on the received countermeasure control information 530, the device 30 for executing countermeasures against disturbances generates a control command for suppressing the output of the renewable energy device 300 or a control command for emergency stop of the renewable energy device 300 and outputs the generated control command to the control execution unit 32- 1. When the control execution unit 32- 1 executes the control for suppressing the output of the renewable energy device 300 or the control for emergency stop of the renewable energy device 300 according to the control command, the output of the renewable energy device 300 is suppressed, and the renewable energy device 300 additionally executes emergency stop in, for example, about 0.2 s (seconds). This can prevent the power flowing through the transmission line or the transformer from exceeding a predetermined amount so as to cause overload.After the generator output and the renewable energy output are suppressed by these countermeasures, the frequency of the power supply system may decrease, so that the power demand of the power supply system needs to be reduced.In this regard, the assumed disturbance stabilization calculation unit 16 performs frequency countermeasure calculation (S 207). At this time, the presumed disturbance stabilization calculation unit 16 performs frequency countermeasure calculation for rapidly increasing the generator output, records the calculation result (output power setting amount) in the countermeasure control table, and transmits the information recorded in the countermeasure control table as countermeasure control information 530 to the disturbance countermeasure execution apparatus 30. At this time, the presumed disturbance stabilization calculation unit 16 performs frequency countermeasure calculation for load shedding, records the calculation result (the load to be shedding) in the countermeasure control table, and transmits the information recorded in the countermeasure control table as countermeasure control information 530 to the disturbance countermeasure execution apparatus 30. In this case, as countermeasure control information 530, generator output setting information for setting the first output and load shedding information for shedding the load of the power supply system are recorded in the countermeasure control table.The interference countermeasure execution device 30 executes the generator output setting processing and the load shedding processing based on the received countermeasure control information 530. For example, if the interference countermeasure execution device 30 executes the generator output adjustment processing, it generates a control command for increasing the output of the thermal force generators 301- 1 and 301- 2, and outputs the generated control command to the control execution unit that controls the thermal force generators 301- 1 and 301- 2. The output power of the thermal force generators 301- 1 and 301- 2 is increased by the control of the control execution unit, and then the frequency of the power supply system is gradually decreased.In addition, if the load shedding processing is executed, the interference countermeasure execution device 30 generates, for example, a control command for shedding the load 400- 1, and outputs the generated control command to the control execution unit 32- 2. When the load 400- 1 is dropped from the control execution unit 32- 2, the frequency of the bus 102 to which the load 400- 1 is connected is gradually decreased.Next, the assumed disturbance stabilization calculation unit 16 performs recovery countermeasure calculation (S 208). At this time, if the presumed failure stabilization calculation unit 16 determines that the frequency of the power supply system may decrease when the load is recovered in the recovery process, it performs recovery countermeasure calculation for increasing the generator output, records the calculation result in the countermeasure control table, and transmits the information recorded in the countermeasure control table as countermeasure control information 530 to the failure countermeasure execution device 30. The information recorded as countermeasure control information 530 in the countermeasure control table in this case is recovery countermeasure information for returning the power flow state of the power supply system to the power flow state before occurrence of a failure satisfying the assumed failure condition, which is generator output setting information for setting the first output.For example, if the interference countermeasure execution device 30 executes the generator output adjustment processing based on the received countermeasure control information 530, it generates a control command for increasing the output of the thermal force generators 301- 1 and 301- 2, and outputs the generated control command to the control execution unit that controls the thermal force generators 301- 1 and 301- 2. The output power of the thermal force generators 301- 1 and 301- 2 is increased by the control of the control execution unit, and then the frequency of the power supply system is gradually increased.In addition, if the presumed malfunction stabilization calculation unit 16 determines in step S 208 that there is a temporary increase in the frequency of the power supply system due to the restart of the temporarily stopped renewable energy device 300 due to, for example, a voltage drop or a voltage increase during the malfunction, executes a recovery countermeasure calculation to inversely reduce the generator output in the generator output adjustment processing by the malfunction countermeasure execution device 30, records the calculation result (output power adjustment amount) in the countermeasure control table, and transmits the information recorded in the countermeasure control table as countermeasure control information to the malfunction countermeasure execution device 30.At this time, if the generator output adjustment processing is executed based on the received countermeasure control information 530, the interference countermeasure execution device 30 generates, for example, a control command for decreasing the output of the thermal force generators 301- 1 and 301- 2, and outputs the generated control command to the control execution unit that controls the thermal force generators 301- 1 and 301- 2. The output of the thermal force generators 301- 1 and 301- 2 is decreased by the control of the control execution unit, and then a transient increase in the frequency of the power supply system is suppressed.Next, the assumed disturbance stabilization calculation unit 16 determines whether a system problem such as overload, voltage drop, and frequency drop has occurred based on the processing results of steps S 204 to S 208 (S 209). If the presumed disturbance stabilization calculation unit 16 determines in step S 209 that there is a system problem, it confirms the operation threshold applied to the system devices at this time as the operation threshold (S 210), and then ends the processing in this routine. If the operation limit value applied to the system devices at this time is the first operation limit value=13000 MW before the renewable energy device 300 is connected to the power supply system, the presumed disturbance stabilization calculation unit 16 confirms the operation limit value as the first operation limit value=13000 MW. Note that, in the processing after step S 211, the assumed disturbance stabilization calculation unit 16 confirms the operation limit value as the second operation limit value if the operation limit value is changed and the operation limit value applied to the system devices is the second operation limit value after the renewable energy device 300 is connected to the power supply system.If the assumed disturbance stabilization calculation unit 16 determines in step S 209 that there is no system problem such as overload, voltage drop, and frequency drop, it performs the setting to increase the operation limit value applied to the system devices at that time (S 211). For example, if the operation threshold applied to the system devices at this time is the first operation threshold=13000 MW, the presumed disturbance stabilization calculation unit 16 increases the operation threshold from 13000 MW by 50 MW to 13050 MW to change it from the first to the second operation threshold.Next, the assumed disturbance stabilization calculation unit 16 changes the setting of the generator output power when the operation limit value applied to the system devices is increased (S 212). For example, the assumed disturbance stabilization calculation unit 16 performs the setting for changing the generator output according to the increase in the operation limit value. At this time, the presumed disturbance stabilization calculation unit 16 is capable of executing the setting for decreasing the output power of the heat generator according to the increase of the operation limit value.Next, the presumed disturbance stabilization calculation unit 16 changes the setting of the renewable energy suppression amount (S 213). At this time, the presumed disturbance stabilization calculation unit 16 performs, for example, a change in setting for reducing the amount of renewable energy suppression. In this case, the presumed disturbance stabilization calculation unit 16 is capable of performing setting for increasing the output of the renewable energy device 300 when the output of the thermal power generator is decreased according to the increase of the operation limit value. Subsequently, the presumed disturbance stabilization calculation unit 16 proceeds to the processing of step S 202 and repeats the processing of steps S 202 to S 213.Note that in a case where setting for decreasing the amount of renewable energy suppression is performed in step S 213, the assumed disturbance stabilization calculation unit 16 generates information on a new assumed power flow area in step S 202, and the power flow on the transmission line, for example, the power flow (P 1+P 2) on the transmission line 100 is increased by increasing the output power of the renewable energy device 300. At this time, the presumed disturbance stabilization calculation unit 16 sequentially changes the output power (first output power) defined by the power generation design value of the heat power generator (first power source), and adds the predicted value of the output power of the renewable energy device 300 as, for example, an output power prediction value assuming a rated output power of 100% or a rated output power of 50% to the changed first output power to generate information on a new presumed power cross section as power flow state information. Subsequently, the assumed disturbance stabilization calculation unit 16 performs processing such as the short-term stability countermeasure calculation (S 204) and the operation limit value increase setting (S 211) on the basis of the newly generated assumed power flow cross-sectional information.FIGS. 7A to 7D are characteristic diagrams showing the state of each part of the system in the case of system failure in the power supply system according to an example of the present invention. FIG. 7A is a characteristic diagram of the phase angle of the generator. FIG. 7B is a characteristic diagram of the terminal voltage of the generator. FIG. 7C is a characteristic diagram of the total output power. FIG. 7D is a characteristic diagram of the frequency of the transmission line.If the system fault 200 indicating a ground fault occurs on a single transmission line of the power supply system, for example, the transmission line 100 over which the total output power P 1 normally flows, as illustrated in FIG. 1, one of the two transmission lines may become unusable and the remaining transmission line may be overloaded by the system fault 200. In addition, the thermal force generator 301- 1 or the thermal force generator 301- 2 starts accelerating due to the voltage drop on the transmission line 100 during the continuation of the system fault 200. In this case, by selecting the renewable energy device 300 and performing an emergency stop within a short time after the occurrence of the system fault 200, the thermal force generator 301- 1 can be prevented from accelerating and shearing out in the vicinity of the point of the system fault 200.Specifically, if the system fault 200 occurs on the transmission line 100, one of the two transmission lines becomes unstable, the remaining transmission line overloads, the phase angle of the heat force generator 301- 1 rapidly increases as illustrated in FIG. 7A, the terminal voltage of the heat force generator 301- 1 rapidly decreases as illustrated in FIG. 7B, the total power decreases below the transmission limit as illustrated in FIG. 7C, and the frequency of the transmission line 100 rapidly increases as illustrated in FIG. 7D. At this time, when the renewable energy device 300 is selected and an emergency stop occurs 0.2 s (seconds) after the occurrence of the system fault 200, the power supply from the renewable energy device 300 to the transmission line 100 is interrupted, and the overload of the remaining transmission line from the transmission line 100 is suppressed. Thereby, 0.2 s (seconds) after the occurrence of the system fault 200, the phase angle of the thermal force generator 301- 1 is gradually shifted to converge to the set value as illustrated in FIG. 7A, the terminal voltage of the thermal force generator 301- 1 is gradually maintained at a predetermined voltage as illustrated in FIG. 7B, the total power is gradually maintained near the transmission limit as illustrated in FIG. 7C, and then the overload of the transmission line 100 is eliminated. In addition, as shown in FIG. 7D, the frequency of the transmission line 100 gradually decreases and is maintained at a specified value.Here, it is to be considered that up to about 10 seconds are required until an emergency stop of the renewable energy device 300. On the other hand, the thermal force generator 301- 2 is far from the point of the system failure 200 and thus can be turned off in several hundred milliseconds. Accordingly, in order to prevent the thermal force generator 301- 1 from accelerating and shearing out, emergency shut-down of the thermal force generator 301- 2 is preferable to emergency stop of the renewable energy device 300.In the case of emergency shutdown of the heat force generator 301- 2, the frequency of the power supply system starts to decrease with a steep characteristic, so that it is necessary to discharge the loads 400- 1 and 400- 2 connected to the transmission line 101 branching from the transmission line 100. Although the voltage of the bus 102 to which the transmission line 101 is connected rises or falls in this case, as the voltage of the bus 102 rises, the magnitudes of the loads 400- 1 and 400- 2 also change, so that it is suitable that the control execution unit 32- 2 independently reselects the load to be dropped on the basis of a value measured by a voltage measurement unit 33 that measures the voltage of the bus 102.In this example, the operation limit value calculation unit 15 functions as an operation limit value control unit (operation limit value control program) that controls the operation limit value with respect to the total output power of the system devices. The presumed malfunction stabilization calculation unit 16 functions as a determination unit (determination program) for calculating the power flow state for each future set time of the power supply system based on the load distribution information including the power generation schedule value of the first power source (thermal power generator), a predicted value of the output power of the second power source (renewable energy device), and a predicted value of the power demand in the power supply system, and determining whether each calculated power flow state is stable by comparing it with the operation threshold.At this time, the determination unit sequentially changes the first output power of the first power source defined by the power generation design value of the first power source, calculates each power flow state based on the power having the changed first output power and a predicted value of the output power of the second power source, and outputs the calculation result to the operation limit control unit. If a positive determination result (stable) is obtained from the determination unit, the operation limit control unit controls the operation limit of the system devices at each time set in the future as the sum of the changed first output power (output power of the heat power generator) and the predicted value of the output power of the second power source added to the changed first output power (predicted value of the output power of the renewable energy device). In addition, the operation limit control unit transmits the operation limit information including the operation limit of the system devices at each time set in the future to the load distribution control system 20. In addition, in the load distribution control system 20, the processing and control may be executed according to the operation limit information.In addition, the assumed malfunction stabilization calculation unit 16 in this example acts as a determination unit (determination program) for determining whether the power supply system is stable, an assumed malfunction condition setting unit (assumed malfunction condition setting program) that sets an assumed malfunction condition indicating a condition of a malfunction that is assumed to occur in the power supply system based on the load distribution information at each time set in the future, and a countermeasure control information generation unit (countermeasure control information generation program) that generates countermeasure control information indicating a control countermeasure if a malfunction satisfies the assumed malfunction condition based on the load distribution information. At this time, the countermeasure control information generation unit is capable of generating, as countermeasure control information, power source holding information for stopping at least a part of the first power source (thermal power generator 301- 2) and the second power source (renewable energy device 300) and load shedding information for shedding the load connected to the first power source if a part of the first power source is stopped, and transmitting the generated power source holding information and load shedding information to the load distribution control system 20 and the fault countermeasure execution device 30. Therefore, the processing and control in the load distribution control system 20 and the fault countermeasure execution device 30 can be executed according to the power source holding information and the load shedding information.In addition, the countermeasure control information generation unit generates, as countermeasure control information 530, congestion countermeasure information for eliminating the load of the first power source becoming congested or short-term stability countermeasure information for maintaining the stability of the power supply system. At this time, the overload countermeasure information and the short-term stability countermeasure information are constituted by a generator output suppression amount for suppressing the first output and a renewable energy output suppression amount for suppressing the second output. In addition, the countermeasure control information generation unit generates voltage maintenance information for maintaining the voltage of the power supply system within a specified voltage range, frequency countermeasure information for maintaining the frequency of the power supply system within a specified frequency range, and recovery countermeasure information for returning the power flow state of the power supply system to the power flow state before occurrence of a failure satisfying an assumed failure condition.According to this example, the operation limit value of the system devices can be changed according to the power flow state of the power supply system even when the output power of the renewable energy device 300 connected to the power supply system is increased. In other words, even in the case of increasing the power output from the renewable energy device 300, by changing the operation limit value of the system devices according to the power flow state of the power supply system, it is possible to reduce the time of overloading the power supply system, reduce the amount of suppression of the renewable energy device 300, promote the introduction of the renewable energy device 300, and reduce the output power of the thermal force generators 301- 1 and 302- 2, so that the CO 2- amount emitted from the thermal force generators 301- 1 and 302- 2 can be reduced. At this time, as countermeasures when the power supply system is unstable, output power setting information for setting at least one of the heat force generators 301- 1, 302- 2, and 302- 3 and the renewable energy device 300 and countermeasure control information related to a failure of the power supply system are prepared, so that a contribution to stabilization of the power supply system can be made. Further, even when the renewable energy source is increased, it is possible to optimize the operating limit of the system devices and prevent unnecessary strong renewable energy suppression.Note that the present invention includes various modification examples without being limited to the above-described examples. For example, in an alternative configuration, a display terminal is installed in the load distribution control system 20 in place of the disturbance countermeasure execution device 30, operation limit information is further displayed as a result of the assumed disturbance stabilization countermeasure calculation and the disturbance recovery calculation, and the information displayed on the display terminal is presented to an operator, a system planning engineer, a system protection engineer, and a system analysis engineer using the load distribution control system 20 as support information.In addition, the renewable energy device 300 is not limited to wind power generation and photovoltaic power generation. Also usable is a device having an inverter such as a storage battery device that stores or generates electric energy, examples of which include a lithium ion battery and a fuel cell.Further, another configuration may be added to the configuration of the example, eliminate it, or replace a part thereof. In addition, the respective above configurations, functions, processing units, processing means, etc. may be realized in whole or in part by hardware, for example, by an integrated circuit-based design. In addition, the respective above configurations, functions, etc. can be realized by software by a processor that interprets and executes a program realizing the respective functions. Information such as a program, a table, and a file, thereby realizing the respective functions, may be recorded on a recording device such as a memory, a hard disk, and a solid state drive (SSD), or on a recording medium such as a smart card (IC card), a secure digital (SD) memory card, and a digital versatile disc (DVD).List of reference characters1 System for a power supply system 10 Renewable energy system stabilization system 11 System configuration generation unit 12 Future power flow area calculation unit 13 General calculation unit 14 System data storage unit 15 Operation limit calculation unit 16 Assumed disturbance stabilization calculation unit 17 Disturbance recovery calculation unit 20 Load distribution control system 30 Disturbance countermeasure execution device 100, 101 Transmission line 102 Bus 300 Renewable energy device 301- 1, 301- 2, 301- 3 Thermal force generator

Claims

A system for stabilizing a renewable energy system (10) that assists operation of a power supply system that connects a load and a first power source including a thermal power generator (301-1, 301-2, 301-3) that generates electricity using at least thermal energy and / or a second power source including a renewable energy device (300) that generates electricity with renewable energy, the system comprising: an operation limit control unit (15) that controls an operation limit with respect to total power of system devices; and a determination unit (16) that determines a power flow state for each future set time of the power supply system based on load distribution information including a power generation plan value of the first power source, a predicted value of the output power of the second power source and a predicted value of the power demand in the power supply system, calculates and determines whether each calculated power flow state is stable by comparing each calculated power flow state with the operation threshold, characterized in that the determination unit (16) sequentially changes the first output power of the first power source defined by the power generation schedule value of the first power source, calculates each of the power flow states based on the power including the changed first output power and the predicted value of the output power of the second power source, and outputs the result of the calculation to the operation threshold control unit (15), and if a positive determination result is obtained from the determination unit (16), the operation limit control unit ( 15) controls the operation limit at each time set in the future as a sum of the changed first output power and the predicted value of the output power of the second power source added to the changed first output power.The renewable energy system stabilization system (10) according to claim 1, wherein the operation limit control unit (15) transmits operation limit information including the operation limit at each time set in the future to a load distribution control system (20) that operates the power supply system.The renewable energy system stabilization system (10) according to claim 1, further comprising an output power setting information generation unit that generates output power setting information for setting the output power of the first power source and / or the output power of the second power source on condition that a negative result is obtained from the determination unit (16).The renewable energy system stabilization system (10) according to claim 3, wherein the output setting information generation unit transmits the output setting information to a load distribution control system operating the power supply system.The renewable energy system stabilization system (10) according to claim 1, further comprising: an assumed failure condition setting unit that sets an assumed failure condition indicating a condition of a failure assumed to occur in the power supply system at each time set in the future on the basis of the load distribution information; and a countermeasure control information generating unit that generates countermeasure control information indicating a control countermeasure on the basis of the load distribution information in a case where a failure satisfies the assumed failure condition.The renewable energy system stabilization system (10) according to claim 5, wherein the countermeasure control information generation unit (30) transmits the countermeasure control information to a fault countermeasure execution device that controls each of the first power source and the second power source as a control object and / or a load distribution control system that operates the power supply system.The renewable energy system stabilization system (10) according to claim 5, wherein the countermeasure control information generation unit (30) generates, as countermeasure control information, power source holding information for stopping at least one of a part of the first power source and the second power source and load shedding information for shedding a load connected to the first power source on condition that a part of the first power source is stopped.The system for stabilizing a renewable energy system (5) according to claim 5, wherein the countermeasure control information generation unit (30) generates, as countermeasure control information, congestion countermeasure information for eliminating a load of the first power source that is congested, short-term stability countermeasure information for maintaining stability with respect to the power supply system, voltage maintenance information for maintaining the voltage of the power supply system within a specified voltage range, frequency countermeasure information for maintaining the frequency of the power supply system within a specified frequency range, and recovery countermeasure information for returning the power flow state of the power supply system to a power flow state before the occurrence of the disturbance satisfying the assumed disturbance condition.A system stabilization support method in a system for supporting the operation of a power supply system that connects a load and a first power source including a thermal power generator (301-1, 301-2, 301-3) that generates electricity using at least thermal energy, and / or a second power source including a renewable energy device (30) that generates electricity with renewable energy, the method comprising: an operation limit control step that controls an operation limit with respect to the total power of system devices; and a determination step that determines a power flow state for each future set time of the power supply system based on load distribution information including a power generation plan value of the first power source, a predicted value of the output power of the second power source and a predicted value of the power demand in the power supply system, calculates and determines whether each calculated power flow state is stable by comparing each calculated power flow state with the operation threshold, characterized in that in the determining step, the first output power of the first power source defined by the power generation schedule value of the first power source is sequentially changed, and each of the power flow states is calculated based on the power including the changed first output power and the predicted value of the output power of the second power source, and in the operation threshold controlling step, on condition that a positive result is obtained in the determining step, the operation limit value at each time set in the future is controlled as a sum of the first output power changed in the determining step and the predicted value of the output power of the second power source added to the changed first output power.The system stabilization support method according to claim 9, wherein in the operation limit control step, operation limit information including the operation limit at each time set in the future is transmitted to a load distribution control system that operates the power supply system.The system stabilization support method according to claim 9, further comprising an output power setting information generating step of generating output power setting information for setting the output power of the first power source and / or the output power of the second power source on the condition that a negative result is obtained in the determining step.The system stabilization support method according to claim 11, wherein the output power setting information is transmitted to a load distribution control system that operates the power supply system in the output power setting information generation step.The system stabilization support method according to claim 9, further comprising: an assumed failure condition setting step of setting an assumed failure condition indicating a condition of a failure assumed to occur in the power supply system at each time set in the future on the basis of the load distribution information; and a countermeasure control information generating step of generating countermeasure control information indicating a control countermeasure in a case where a failure satisfies the assumed failure condition on the basis of the load distribution information.The system stabilization support method according to claim 13, wherein in the countermeasure control information generation step, the countermeasure control information is transmitted to a failure countermeasure execution device that controls each of the first power source and the second power source as a control object and / or a load distribution control system that operates the power supply system.The system stabilization support method according to claim 13, wherein in the countermeasure control information generation step, power source holding information for stopping at least one of a part of the first power source and the second power source and load shedding information for shedding a load connected to the first power source under the condition that a part of the first power source is stopped are generated as countermeasure control information.

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