Power system stabilization device and power system stabilization method

Abstract

To provide a power system stabilization device and a power system stabilization method for evaluating the stabilization effect of electrical control of a synchronous generator and a renewable energy power source.SOLUTION: A power system stabilization device performs correction control by controlling power of one or more types of synchronous machines and renewable energy power sources in the event of a failure, and by additionally controlling power on the basis of post-calculation at the time of the failure when the amount of power control is insufficient. A post-calculation unit includes: a simple system creation unit that creates a simple system model composed of an accelerating synchronous machine and a renewable energy power source on the basis of the results of pre-calculation and failure information; a power phase difference angle curve estimation unit that applies post-measurement information at the time of the failure to the simple system model to estimate a power phase difference angle curve that shows the relationship between the power and phase difference angle of the power system when additional power control is performed by the accelerating synchronous machine and the renewable energy power source; and a correction control target selection unit that selects either the accelerating synchronous machine or the renewable energy power source as an additional power control target on the basis of the estimated result of the power phase difference angle curve.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power system stabilization device and a power system stabilization method for maintaining the stability of a power system. [Background technology]

[0002] When a fault (fault) occurs in a power system due to a lightning strike or other cause, the output of some synchronous generators (SG) may become unstable. If effective measures are not taken to prevent this instability, the number of unstable synchronous generators will increase over time, and this could ultimately lead to a major blackout.

[0003] To address the above-mentioned problems, conventional power system stabilizers have maintained the transient stability of a power system by isolating unstable synchronous generators from the power system in the event of a fault, i.e., by limiting power supply (shearing). For example, the power system stabilizer described in Non-Patent Document 1 periodically calculates in advance through a numerical simulation using online measurement information of the power system which synchronous generators to shear off to maintain transient stability in the event of a contingency fault in the power system, and performs stabilization control (first-stage control) to shear off the synchronous generator when a contingency fault actually occurs. Note that stabilization control does not only involve the above-mentioned shearing, but also includes methods of suppressing or stopping generator output, but hereinafter, the term shearing control will also include suppressing and stopping generator output.

[0004] On the other hand, in recent years, in order to reduce CO2 emissions, renewable energy sources (RES), such as solar and wind power, have been actively introduced as alternatives to synchronous generators, such as those used in thermal power plants, and the proportion of synchronous generators in power grids has been decreasing. However, as the proportion of synchronous generators decreases, the inertia and voltage maintenance capabilities of the power grid, which were previously handled by synchronous generators, decrease, which may result in a decrease in transient stability. Furthermore, renewable energy sources such as solar and wind power fluctuate in power output depending on weather conditions, affecting the power flow state of the power grid. Because stability during a fault varies depending on the power flow state, if a fluctuation in the output of a renewable energy source occurs during a calculation period, the shedding capacity of the first-stage control may be insufficient compared to the actual shedding capacity, potentially preventing stabilization.

[0005] To address the above-mentioned problem, the power system stabilizer described in Non-Patent Document 1 performs post-fault calculations after a fault to additionally control synchronous generators by the amount required for stabilization when the amount of shedding in the first-stage control is insufficient. Specifically, based on the results of pre-calculation, the synchronous generators at the time of the fault are grouped into unstable generators and stable generators, and a simplified system is constructed in which each of the two groups is simply modeled with one generator. Then, from this simplified system, a relational expression between the power output of the unstable generators and the internal phase difference angle (power phase difference angle curve) is derived, and the equal area method is applied to the power phase difference angle curve to calculate the corrective control amount of the synchronous generators required for stabilization.

[0006] Furthermore, Patent Document 1 aims to improve the calculation accuracy of correction control by correcting a power phase difference angle curve using pre-calculation results and system measurement data after a fault, and describes it as "a power system stabilization system that, when a fault occurs in the power system, stabilizes the power system by controlling the output from a generator that is a control target in accordance with the fault condition, the power system stabilization system comprising: pre-calculation means that determines a control pattern for each expected fault by performing stability calculations using state values ​​of the generator that is a control target and a generator that is not a control target, and calculates a correction amount that indicates the amount of influence of fluctuations of the generator that is a control target and the generator that is not a control target caused by each fault; and post-calculation means that, when a fault occurs, generates a model for determining the transient stability of the power system based on actual measurement values ​​measured from the generator that is a control target, and reflects the correction amount in the generated model and performs control in accordance with the control pattern." [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-25715 [Non-patent literature]

[0008] [Non-Patent Document 1] Hiroshi Yoshida, Ryuji Tate, Koya Takafuji, Hironori Imaeda, Masaru Takeishi, Hiroyuki Taguchi, and Kenichiro Kusaba: "Development of an Integrated Online Power System Stabilization System (ISC) for Next-Generation Grids," Journal of Electrical Engineering B, Vol. 137, No. 6, pp. 434-445 (2017) Summary of the Invention [Problem to be solved by the invention]

[0009] In Non-Patent Document 1 and Patent Document 1, the power phase angle curve is derived based on a simple system model in which the power supply is composed only of synchronous generators. Therefore, the formula that represents the power phase angle curve does not include parameters that represent the state quantities of renewable energy power sources, and it is not possible to represent changes in the shape of the power phase angle curve due to the shedding of renewable energy power sources. Therefore, it is not possible to evaluate the stabilizing effect of shedding of renewable energy power sources, and therefore they cannot be selected as targets for correction control.

[0010] As a result of the above, in power systems with a high proportion of renewable energy sources, the targets of corrective control are limited to synchronous generators, which may make it difficult to maintain transient stability through corrective control and may increase the total amount of power control required to maintain transient stability (the cost required to recover from power control).

[0011] Therefore, in order to maintain transient stability even in power systems with a large proportion of renewable energy sources, a method is required that can evaluate the stabilizing effect of electrical control on not only synchronous generators but also renewable energy sources, and select the synchronous generators and renewable energy sources to be corrected and controlled based on the evaluation results.

[0012] In view of the above, the problem to be solved by the present invention is to provide a power system stabilization device and a power system stabilization method that are equipped with a correction control algorithm that can evaluate the stabilization effect of electrical control of synchronous generators and renewable energy power sources. [Means for solving the problem]

[0013] In light of the above, the present invention provides a power system stabilization device that performs first-stage control to control power output of one or more of a synchronous machine and a renewable energy power source in the event of a failure based on a pre-calculation of stability in the event of an anticipated failure in a power system including a synchronous machine and a renewable energy power source, and performs corrective control to perform additional power output control based on a post-calculation in the event of a failure if the amount of power output controlled by the first-stage control is insufficient, wherein the post-calculation unit that performs the post-calculation in the event of a failure comprises: a simple system creation unit that creates a simple system model consisting of the accelerating synchronous machine and the renewable energy power source based on the results of the pre-calculation and failure information; a power phase angle curve estimation unit that applies the post-measurement information in the event of the failure to the simple system model to estimate a power phase angle curve that shows the relationship between power and phase angle in the power system when additional power output control by the accelerating synchronous machine and the renewable energy power source is performed; and a corrective control target selection unit that selects one or more of the accelerating synchronous machine and the renewable energy power source as targets for additional power output control based on the estimation result of the power phase angle curve in the power phase angle curve estimation unit.

[0014] Furthermore, the present invention is a power system stabilization method that uses a computer to implement first-stage control to control power output of one or more of synchronous machines and renewable energy power sources in the event of a failure, based on a pre-calculation of stability in the event of an anticipated failure in a power system including synchronous machines and renewable energy power sources, and to implement corrective control to perform additional power output control based on a post-calculation in the event of a failure if the amount of power output controlled by the first-stage control is insufficient, wherein the post-calculation in the event of a failure comprises creating a simple system model consisting of accelerating synchronous machines and renewable energy power sources based on the results of the pre-calculation and failure information, applying post-measurement information in the event of a failure to the simple system model to estimate a power phase difference angle curve that shows the relationship between power and phase difference angle in the power system when additional power output control by the accelerating synchronous machines and renewable energy power sources is implemented, and selecting one or more of accelerating synchronous machines and renewable energy power sources to be subjected to additional power output control based on the estimated result of the power phase difference angle curve. [Effects of the Invention]

[0015] This invention makes it possible to evaluate the stabilizing effect of power control on synchronous generators and renewable energy power sources, and to perform corrective control of the synchronous generators and renewable energy power sources based on the evaluation results.This makes it possible to maintain transient stability even in power systems with a high proportion of renewable energy power sources, and to reduce the total amount of power control required to maintain transient stability (the cost required to recover from power control). [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing an example of the functional configuration of a power system stabilizing device 1 according to a first embodiment of the present invention. [Figure 2] 1 is a diagram showing an example of the hardware configuration of a power system stabilizing device 1 according to a first embodiment of the present invention. [Figure 3] 1 is a diagram showing an example of the configuration of a program held in a program database DB50 of a power system stabilizing device 1 according to a first embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing an example of the data structure of system configuration data D211 according to the first embodiment of the present invention. [Figure 5] FIG. 2 is a diagram showing an example of the data structure of system measurement value data D212 according to the first embodiment of the present invention. [Figure 6] FIG. 2 is a diagram showing an example of the data structure of system model data D213 according to the first embodiment of the present invention. [Figure 7] FIG. 2 is a diagram showing an example of the data structure of contingent fault list data D214 according to the first embodiment of the present invention. [Figure 8] FIG. 2 is a diagram showing an example of the data structure of threshold data D215 according to the first embodiment of the present invention. [Figure 9] FIG. 2 is a diagram showing an example of the data structure of electrical control selection setting data D216 according to the first embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing an example of the data structure of accelerator / electrical control candidate data D223 according to the first embodiment of the present invention. [Figure 11] FIG. 2 is a diagram showing an example of the data structure of synthetic impedance data D224 according to the first embodiment of the present invention. [Figure 12] FIG. 2 is a diagram showing an example of the data structure of first-stage control object data D225 according to the first embodiment of the present invention. [Figure 13]FIG. 10 is a diagram showing an example of the data structure of power control selection order data D226 according to the first embodiment of the present invention. [Figure 14] FIG. 10 is a diagram showing an example of the data structure of failure information data D411 according to the first embodiment of the present invention. [Figure 15] FIG. 10 is a diagram showing an example of the data structure of synchronous machine / renewable energy measurement value data D412 according to the first embodiment of the present invention. [Figure 16] FIG. 10 is a diagram showing an example of the data structure of mathematical model data D413 according to the first embodiment of the present invention. [Figure 17] 2 is a diagram showing an overall flow of processing of the master station 2 of the power system stabilizing device 1 according to the first embodiment of the present invention. FIG. [Figure 18] 2 is a diagram showing an overall flow of processing of a slave station 4 of the power system stabilizing device 1 according to the first embodiment of the present invention. FIG. [Figure 19] FIG. 4 is a diagram showing an example of detailed processing of a simple system creation unit 41 in a slave station 4 of the present invention. [Figure 20] 4 is a diagram showing a processing image of a simple system creation unit 41 in a slave station 4 of the present invention. FIG. [Figure 21] 4 is a diagram showing an example of detailed processing of a power phase difference angle curve estimating unit 42 in a slave station 4 of the present invention. FIG. [Figure 22A] 4 is a diagram showing inverter characteristics of a renewable energy power source taken into consideration by a power phase difference angle curve estimation unit 42 of a slave station 4 of the present invention. FIG. [Figure 22B] 4 is a diagram showing inverter characteristics of a renewable energy power source taken into consideration by a power phase difference angle curve estimation unit 42 of a slave station 4 of the present invention. FIG. [Figure 23A] 4 is a diagram showing an example of the acceleration energy / deceleration energy calculation process in the power phase difference angle curve estimating unit 42 of the slave station 4 of the present invention (when controlling an accelerating synchronous machine). FIG. [Figure 23B] 4 is a diagram showing an example of the acceleration energy / deceleration energy calculation process in the power phase difference angle curve estimating unit 42 of the slave station 4 of the present invention (when controlling a renewable energy power source). FIG. [Figure 24] FIG. 4 is a diagram showing an example of detailed processing of a correction control target selection unit 44 in the slave station 4 of the present invention. [Figure 25] FIG. 3 is a diagram showing an example of a result display by the display unit 6 of the present invention. [Figure 26] 1 is a diagram showing the effect of the present invention on the stability of the power system. [Figure 27] FIG. 1 is a diagram showing an example of the configuration of a power system stabilization device 1 according to a second embodiment of the present invention. [Figure 28] FIG. 10 is a diagram showing an example of the hardware configuration of a power system stabilizing device 1 according to a second embodiment of the present invention. [Figure 29] FIG. 10 is a diagram showing an example of the configuration of a program held in a program database DB50 of a power system stabilizing device 1 according to a second embodiment of the present invention. [Figure 30A] FIG. 10 is a diagram showing an image of renewable energy output characteristic pattern data D218 (a pattern in which the output instantly returns to the level before the failure) in Example 2 of the present invention. [Figure 30B] FIG. 10 is a diagram showing an image of renewable energy output characteristic pattern data D218 (a pattern in which the output returns to the pre-failure level at a ramp rate at time T1) in Example 2 of the present invention. [Figure 30C] FIG. 10 is a diagram showing an image of renewable energy output characteristic pattern data D218 (a pattern that does not return after a fault is removed) in Example 2 of the present invention. [Figure 31] FIG. 10 is a diagram showing an overall flow of processing in a master station 2 of a power system stabilizing device 1 according to a second embodiment of the present invention. [Figure 32] FIG. 10 is a diagram showing an overall flow of processing in a slave station 4 of a power system stabilizing device 1 according to a second embodiment of the present invention. [Figure 33] FIG. 10 is a diagram showing a processing image of a renewable energy output amount result calculation unit 45 and a correction control target selection unit 44 in Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0018] In this invention, "stability" and "stability" are explained as synonyms. Furthermore, "synchronous machine" and "renewable energy" are used as abbreviations for "synchronous generator" and "renewable energy power source," respectively, and "generator" is used as a general term for "synchronous generator" and "renewable energy power source." [Example]

[0019] First, an example of the functional configuration of a power system stabilizing device 1 according to a first embodiment will be described with reference to FIG.

[0020] The power system stabilization device 1 is composed of a master station 2 that performs pre-calculation before a power system failure occurs, a slave station 4 that uses the pre-calculation results of the master station 2 to perform post-calculation after a failure occurs, a communication unit 3 that transmits the pre-calculation results of the master station 2 to the slave station 4, and an output unit 6 that outputs the calculation results of the master station 2 and the slave station 4 (in the following, the output unit will be exemplified by a display unit such as a monitor).

[0021] The master station 2, which is configured using a computer, is composed of a pre-calculation input database DB21 that holds pre-calculation input data D21 that is held in advance by a power system operator or planner, a pre-calculation unit 20 that performs pre-calculation based on the pre-calculation input data D21, and a pre-calculation output database DB22 that stores pre-calculation output data D22, which is the calculation result of the pre-calculation unit 20.

[0022] Of these, the pre-calculation input database DB21 is composed of a system configuration database DB211 that holds system configuration data D211, a system measurement value database DB212 that holds system measurement value data D212, a system model database DB213 that holds system model data D213, a contingency fault list database DB214 that holds contingency fault list data D214, a threshold value database DB215 that holds threshold value data D215, and a power control selection setting database DB216 that holds power control selection setting data D216.

[0023] If we express the processing contents of the pre-calculation unit 20 functionally, it is composed of the functions of an analysis section creation unit 21, a transient stability calculation unit 22, an acceleration synchronous machine / electrical control candidate extraction unit 23, a synthetic impedance calculation unit 24, and an electric control selection order calculation unit 25, and the processing is executed in this order.

[0024] The pre-calculation output database DB22 is composed of an analysis cross section database DB221 that holds analysis cross section data D221, a stability calculation result database DB222 that holds stability calculation result data D222, an accelerator / power control candidate database DB223 that holds accelerator / power control candidate data D223, a synthetic impedance database DB224 that holds synthetic impedance data D224, a first-stage control object database DB225 that holds first-stage control object data D225, and a power control selection order database DB226 that holds power control selection order data D226.

[0025] The slave station 4, which is constructed using a computer, is composed of a post-calculation input database DB41 that holds post-calculation input data D41 including the pre-calculation results of the master station 2 and data obtained from the power system after a fault occurs, a post-calculation unit 40 that performs post-calculation based on the post-calculation input data D41, a pre-calculation output database DB42 that stores post-calculation output data D42, which is the calculation result of the post-calculation unit 40, and a control unit 5 that transmits control commands (electrical control commands) to the control objects calculated by the master station 2 and the slave station 4.

[0026] The post-calculation input database DB41 is composed of a database that stores data of the calculation results in the parent station 2 and a database that stores data unique to the child station 4. The former databases are an accelerator / shearing control candidate database DB223, a synthetic impedance database DB224, a first-stage control target database DB225, and a shearing control selection order database DB226. The latter databases unique to the child station 4 are a fault information database DB411 that holds fault information data D411, a synchronous machine / renewable energy measurement value database DB412 that holds synchronous machine / renewable energy measurement value data D412, and a mathematical model database DB413 that holds mathematical model data D413.

[0027] The post-calculation unit 40, when expressed functionally, is composed of the functions of a simple system creation unit 41, a power phase difference angle curve estimation unit 42, a stability determination unit 43, and a correction control target selection unit 44, and executes the processing in this order.

[0028] The post-computation output database DB42 is composed of a simple system database DB421 that holds simple system data D421, a power phase difference angle curve database DB422 that holds power phase difference angle curve data D422, a stability judgment result database DB423 that holds stability judgment result data D423, and a correction control object database DB424 that holds correction control object data D424.

[0029] Fig. 2 shows an example of the hardware configuration of the power system stabilization device 1 of the first embodiment. The upper part of Fig. 2 shows an example of the hardware configuration of the power system stabilization device 1, and the lower part shows an example of the configuration of the power system 100 that is the object of control.

[0030] The power system stabilization device 1 in this diagram is made up of various databases (DB211-DB216, DB221-DB226, DB411-DB413, DB421-DB424), a program database DB50, a communication unit 3, a control unit 5, a display unit 6, an input unit 7, a processor 8, a memory 9, and a bus line 10 connecting these. Note that in Fig. 2, no distinction is made between parent station equipment and child station equipment, and all functions of the power system stabilization device 1 as a whole are described.

[0031] The group of programs held by the program database DB50 is shown in Figure 3. Although not shown in Figure 1, the program database DB50 consists of an analysis section creation program Pr1, a transient stability calculation program Pr2, an acceleration synchronous machine / shear control candidate extraction program Pr3, a synthetic impedance calculation program Pr4, a shear control selection order calculation program Pr5, a simple system creation program Pr6, a power phase difference angle curve estimation program Pr7, a stability determination program Pr8, and a correction control target selection program Pr9.

[0032] Returning to FIG. 2, the communication unit 3 exchanges data with the power system 100 via the communication network 200.

[0033] The control unit 5 receives the first stage control object data D225 created by the master station 2 from the communication unit 3 via the communication network 200.

[0034] Furthermore, when a fault occurs in the power system 100, the control unit 5 compares the fault information acquired from the measuring devices 30a-30b with the first-stage control target data D225, and transmits a first-stage control command to the terminal stations (transfer cutoff devices) to be controlled among the generators 110a-110c, such as synchronous generators or renewable energy power sources. In addition, if the power system 100 cannot be stabilized by the first-stage control, the control unit 5 transmits a corrected control command to the remaining terminal stations to be controlled among the generators 110a-110c, based on the corrected control target data D424 created by the slave station 4.

[0035] The display unit (output unit in a broader sense) 6 is configured with, for example, one or more of a display device, a printer device, a projector device, an audio output device, etc. The display unit 6 displays one or more of various input / output data (D211 to D216, D221 to D226, D411 to D413, D421 to D424) on a screen. Examples of the screen to be displayed will be described later.

[0036] The input unit 7 is configured with, for example, one or more of a keyboard, a switch, a mouse, a touch panel, a voice input device, and the like.

[0037] The processor 8 reads a program required for the processing of the calculation unit 2 from the various programs constituting the program database DB50 and executes the calculation. The processor may be configured with one or more semiconductor chips, or may be configured with a computer or calculator.

[0038] The memory 9 is configured by a storage device such as a RAM (Random Access Memory), and stores programs read from a program database DB50, various input / output data (D211 to D216, D221 to D226, D411 to D413, D421 to D424), and the like.

[0039] An example power system 100 shown in the lower part of Figure 2 is composed of generators 110a to 110c, such as synchronous generators and renewable energy power sources, nodes (buses) 120a to 120c and 121a to 121c, transformers 130a to 130c, branches (lines) 140a to 140c, etc.

[0040] The power system 100 also includes measuring devices 30a to 30b. The measuring devices 30a to 30b are linked to the power system stabilization device 1 via a communication network 200.

[0041] The measuring devices 30a to 30b acquire one or more of the following as system measurement value data D212 or synchronous machine / renewable energy measurement value data D412: TM (Telemeter) information such as the output of generators 110a to 110c, voltage values ​​at each node 120a to 120c and 121a to 121c, values ​​of active power and reactive power flowing through transformers 130a to 130c and branches 140a to 140c, and SV (Super Vision) information on the switching of circuit breakers at nodes, transformers, branches, and phase modifying equipment, and transmit it to the communication unit 3.

[0042] Furthermore, when a fault occurs in the power system 100, the measuring devices 30a to 30b detect information such as the location and nature of the fault, and transmit this information to the communication unit 3 and the control unit 5 via the communication network 200 as fault information data D411.

[0043] The power system stabilizing device 1 can periodically acquire TM information and SV information from the measuring devices 30a to 30b via the communication network 200 and store the information in various databases.

[0044] Here, the data D211 to D216 held in the various input databases DB211 to DB216 will be described with reference to the drawings.

[0045] 4 shows an example of system configuration data D211 held in the system configuration database DB211. As shown expanded vertically, the system configuration database DB211 stores information on the branches (lines) and synchronous generators that make up the power system, as well as information on loads, renewable energy power sources, transformers, phase modifying equipment, and the like (which can be considered equipment that makes up the power system).

[0046] The data that should be held for these devices is, as shown horizontally, for branches, the transmission line number, number of lines, node numbers at both ends, resistance, reactance, etc., and for the same devices, it is good to hold the synchronous generator number, interconnecting node, number of parallel units, rated capacity, rated output, reactance, etc. In the cases of loads, renewable energy sources, transformers, phase modifying equipment, etc., appropriate information will also be held.

[0047] 5 shows an example of system measurement value data D212 held in the system measurement value database DB212. The system measurement value database DB212 stores one or more of the following information acquired via the communication network 200: the output of generators 110a-110c of power system 100; voltage values ​​at each of nodes 120a-120c and 121a-121c; values ​​of active power and reactive power flowing through transformers 130a-130c and branches 140a-140c; and on / off information for circuit breakers at nodes, transformers, branches, and phase modifying equipment. This information is stored in chronological order for each measurement location, linked to timestamp information indicating the date and time of measurement.

[0048] Figure 6 shows an example of system model data D213 stored in the system model database DB213. In the system model database DB213 of Figure 6, synchronous generators, renewable energy power sources, and loads required for numerical analysis of power systems using computers or calculators are described in a vertically expanded format, and information on the model types related to these models and the constants used therein is stored in a horizontally expanded format. In Figure 6, the description "SG" in the equipment name column represents a synchronous generator, and "RES" represents a renewable energy power source, and these notations will be used where appropriate in the following illustrations.

[0049] 7 shows an example of the contingency fault list data D214 held in the contingency fault list database DB214. The contingency fault list database DB214 stores information on the location (fault point), the fault state, the duration, etc. of each contingency fault in the power system.

[0050] 8 shows an example of threshold data D215 held in the threshold database DB215. The threshold database DB215 stores, for each of contingent faults A, B, and C in the power system, threshold values ​​for the internal phase difference angle, threshold values ​​for the output change rate before and after the occurrence of a fault, and the like, as threshold data used for extraction by the acceleration synchronous machine / electrical control candidate extraction unit 23.

[0051] 9 shows an example of the shedding control selection setting data D216 stored in the shedding control selection setting database DB216. The shedding control selection setting database DB216 stores information regarding generators such as synchronous generators SG and renewable energy power sources RES, such as whether or not each generator can be shedding-controlled, and if so, the timing of shedding. In the example shown, it is set that synchronous generator SG3 will not be used for shedding.

[0052] Next, the following describes, with reference to the drawings, the data D223 to D226 held in the various output databases DB223 to DB226 constituting the master station 2 of the power system stabilizing device 1. The data D223 to D226 are also used as part of the post-calculation input data D41 of the slave station 4.

[0053] Figure 10 shows an example of accelerator / shutter control candidate data D223 stored in the accelerator / shutter control candidate database DB223. The accelerator / shutter control candidate database DB223 stores the names of the accelerator synchronous machines and the shedding candidate machines for each contingency fault, as well as additional information on the accelerator synchronous machines and shedding candidate machines required for post-fault calculations. Examples of additional information on the accelerator synchronous machines include the initial active power output, initial reactive power output, initial terminal voltage, and inertia constant. Examples of additional information on the shedding candidate machines include the initial active power output, initial reactive power output, initial terminal voltage, and initial terminal voltage phase angle. An accelerator synchronous machine is a synchronous generator selected from multiple synchronous generators with the aim of using it for shedding control; the selection method will be described separately later.

[0054] 11 shows an example of the synthetic impedance data D224 held in the synthetic impedance database DB224. The synthetic impedance database DB224 stores, for each contingent fault, a list of acceleration synchronous machines, and the impedance (synthetic impedance) value of a one-machine infinite bus system when the power system 100 is represented as a one-machine infinite bus system.

[0055] 12 shows an example of first-stage control target data D225 held in the first-stage control target database DB225. The first-stage control target database DB225 stores, for each contingent fault, a list of acceleration synchronous machines and renewable energy power sources that are to be subject to first-stage control, the value of their total power control amount, and the like.

[0056] 13 shows an example of shedding control selection order data D226 held in the shedding control selection order database DB226. The shedding control selection order database DB226 stores, as shedding control selection orders, the order of acceleration synchronous machines and renewable energy power sources that are effective for stabilizing the power system for each contingent fault.

[0057] Next, the data D411 to D413 held in the various output databases DB411 to DB413 constituting the slave station 4 of the power system stabilizing device 1 will be described with reference to the drawings.

[0058] 14 shows an example of the failure information data D411 held in the failure information database DB411. The failure information database DB411 stores information such as the time of occurrence, the location of the failure, and the nature of the failure when a failure actually occurs in the power system 100.

[0059] 15 shows an example of synchronous machine / renewable energy measurement value data D412 held in the synchronous machine / renewable energy measurement value database DB412. The synchronous machine / renewable energy measurement value database DB412 stores post-measurement data of the acceleration synchronous machine and renewable energy power source in chronological order.

[0060] 15 shows an example of synchronous machine / renewable energy measurement value data D412 held in the synchronous machine / renewable energy measurement value database DB412. The synchronous machine / renewable energy measurement value database DB412 stores post-measurement data of the acceleration synchronous machine and the renewable energy power source.

[0061] Fig. 16 shows an example of mathematical model data D413 held in the mathematical model database DB413. The mathematical model database DB413 stores data such as the names, formulas, and constants in the formulas of various mathematical models used in the power phase difference angle curve estimation unit 42. The model names in Fig. 16 are the power flow equation, the oscillation equation, the supply and demand balance equation, the kinetic energy equation, and the equations related to renewable energy output current.

[0062] Next, the processing contents of the pre-calculation unit 20 of the master station 2 will be described with reference to Fig. 17. Fig. 17 shows the overall flow of the processing of the master station 2 in the first embodiment. This processing is executed periodically when the power system 100 is in normal operation. The flow of the calculation processing will be described for each processing step.

[0063] First, in processing step S21, the analysis cross-section creation program Pr1 is executed using the system configuration data D211 (Figure 4), system measurement value data D212 (Figure 5), and system model data D213 (Figure 6), and analysis cross-section data D221 of the power system 100 at the current time is created and registered in the analysis cross-section database DB221.

[0064] Next, in processing step S22a, the transient stability calculation program Pr2 is executed using the analysis cross-section data D221 and the expected fault list data D214 (Figure 7) under the condition that none of the generators are powered down, and stability calculation result data D222 for the power system 100 is output and registered in the stability calculation result database DB222.

[0065] Next, in processing step S22b, it is determined whether the power system 100 is transiently stable or unstable based on the stability calculation result data D222. Stability is determined using, for example, the internal phase difference angle, frequency, and voltage of a synchronous generator as indicators. If the power system 100 is stable ("YES" in processing step S22b), this processing flow ends. If the power system 100 is unstable ("NO" in processing step S22b), the processing proceeds to processing step S23, which will be described later.

[0066] Next, in processing step S23, the acceleration synchronous machine / power control candidate extraction program Pr3 is executed using the threshold data D215 (Figure 8) and the stability calculation result data D222, and accelerator / power control candidate data D223 is output and registered in the accelerator / power control candidate database DB223.

[0067] The registered accelerator and shedding candidates are shown in Fig. 10, which shows that when the expected fault is A, SG1, SG2, and SG5 are selected as the accelerator synchronous machines, and SG1, SG2, RES1, and RES2 are selected as the shedding candidates. Similar accelerator and shedding candidates are set for faults B and C in the same way.

[0068] The accelerated synchronous machine is defined as an accelerated synchronous machine by selecting one that meets a judgment condition from among synchronous machines present in the power system. Methods for judging an accelerated synchronous machine include, for example, a method of judging a synchronous generator whose speed deviation is always positive in the time range from after a fault occurs to the transient stability calculation end time as an accelerated synchronous machine, a method of judging a synchronous generator whose internal phase difference angle exceeds a threshold value specified by threshold data D215 at the transient stability calculation end time as an accelerated synchronous generator, and a method of judging a synchronous generator whose internal phase difference angle exceeds the internal phase difference angle of the center of inertia of all synchronous generators in power system 100 as an accelerated synchronous generator.

[0069] In addition, as a method for determining candidates for power control, for example, there is a method in which a synchronous generator SG and a renewable energy power source RES for which the value of equation (1) is below the threshold value specified by the threshold value data D215 (FIG. 8) are determined to be candidates for power control.

[0070]

number

[0071] Here, ΔP in equation (1) i represents the rate of change of the active power output of the synchronous generator or renewable energy source just before and after the occurrence of a contingency fault, and P i1 represents the active power output of the synchronous generator or renewable energy source just before the occurrence of a contingency fault, and P i2 represents the active power output of synchronous generators and renewable energy sources immediately after a contingency fault occurs. Also, G represents the set of all synchronous generators and renewable energy sources that can be dispatched.

[0072] The formula for determining candidates for power control is not limited to formula (1). For example, the deviation or rate of change of the voltage of a synchronous generator or a renewable energy power source immediately before and after the occurrence of a contingency fault may be used as the formula for determination.

[0073] Next, in processing step S24, the stability calculation result data D222 and the accelerator / electrical control candidate data D223 (FIG. 10) are used to execute the synthetic impedance calculation program Pr4, output synthetic impedance data D224, and register it in the synthetic impedance database DB224.

[0074] The registered composite impedance is shown as an example in Fig. 11. Here, when the contingency fault is A, the accelerating synchronous machines SG1, SG2, and SG5 are treated as an accelerating synchronous machine group, and when the contingency fault is B, the accelerating synchronous machines SG1, SG2, SG3, SG4, etc. are treated as an accelerating synchronous machine group, and the composite impedance of these accelerating synchronous machine groups is determined and stored for each contingency fault.

[0075] As a method for calculating the composite impedance, for example, as described in Non-Patent Document 1, there is a method in which a model of the power system 100 is converted into a one-machine infinite bus system model consisting of one equivalent generator which is an aggregation of a group of acceleration synchronous machines and an infinite bus, and the impedance between the equivalent generator and the infinite bus is taken as the composite impedance.

[0076] Next, in processing step S25, the power control selection setting data D216 (Figure 9), the stability calculation result data D222, and the accelerator / power control candidate data D223 (Figure 10) are used to execute the power control selection order calculation program Pr5, outputting first-stage control object data D225 and power control selection order data D226, which are then registered in the first-stage control object database DB225 and the power control selection order database DB226, respectively, and the processing is terminated.

[0077] An example of the registered first-stage control target data D225 is shown in Fig. 12. Here, it is stored that when the contingency fault is A, the acceleration synchronous machine SG1 and the renewable energy power sources RES1 and RES2 are set as the first-stage control targets, and when the contingency fault is B, the acceleration synchronous machines SG1 and SG2 and the renewable energy power sources RES1 and RES2, etc. are set as the first-stage control targets.

[0078] An example of the registered shedding control selection order data D226 is shown in Fig. 13. Here, it is stored that when the contingency fault is A, the shedding control selection order is renewable energy power source RES1, acceleration synchronous machine SG1, and renewable energy power source RES2 in that order, and when the contingency fault is B, the shedding control selection order is acceleration synchronous machine SG1, renewable energy power source RES1, and acceleration synchronous machine SG2 in that order.

[0079] Next, the processing contents of the post-calculation unit 40 of the slave station 4 will be described with reference to Fig. 18. Fig. 18 shows the overall flow of the processing of the slave station 4 in the first embodiment. This processing is executed when a fault actually occurs in the power system 100. The flow of the calculation processing will be described for each processing step.

[0080] First, in processing step S41, the simple system creation program Pr6 is executed using the accelerator / electrical control candidate data D223 (Figure 10), the synthetic impedance data D224 (Figure 11), and the fault information data D411 (Figure 14), to create simple system data D421 and register it in the simple system database DB421.

[0081] The simplified system indicated by the registered simplified system data D421 will be described in detail using FIG. 20. In essence, it is a simplified power system in which an acceleration synchronous machine group and a renewable energy power source group are connected to an infinite bus, and the power, voltage, impedance, etc. at each point on the power system are described and stored.

[0082] Next, in processing step S42, the power phase difference angle curve estimation program Pr7 is executed using the first-stage control object data D225 (FIG. 12), the synchronous machine / renewable energy measurement value data D412 (FIG. 15), the mathematical model data D413 (FIG. 16), and the simple system data D421 to create power phase difference angle curve data D422 and register it in the power phase difference angle curve database DB422.

[0083] The power phase difference angle curve indicated by the registered power phase difference angle curve data D422 will be described in detail using Figs. 23A and 23B. In essence, the power phase difference angle curve is an estimate on the power phase difference angle curve of how the relationship between power and phase difference angle changes when the acceleration synchronous machine and the renewable energy power source are each controlled.

[0084] Next, in processing step S43, the stability determination program Pr8 is executed using the power phase difference angle curve data D422 (FIGS. 23A and 23B), stability determination result data D423 is generated, and the stability determination result data D423 is registered in the stability determination result database DB423. If the system is stable ("YES" in processing step S43), this processing flow ends. If the system is unstable ("NO" in processing step S43), the process proceeds to processing step S44, which will be described later.

[0085] Next, in processing step S44, the power control selection order data D226 (Figure 13), the power phase difference angle curve data D422 (Figures 23A and 23B), and the stability judgment result data D423 are used to select the corrected control objects necessary for stabilization, and the selection results are output as corrected control object data D424 and registered in the corrected control object database DB424.

[0086] A detailed flow of the simple system creation process S41 is shown in Fig. 19. The creation procedure will be explained for each processing step in Fig. 19.

[0087] First, in processing step S411, fault information is read from the fault information data D411. Next, in processing step S412, the accelerator / shunt control candidate data D223 and the composite impedance data D224 calculated for each contingent fault are referenced, and the accelerator synchronous machine / shunt control candidate and the composite impedance of the contingent fault that match the acquired fault information are identified.

[0088] Next, in processing step S413, the average absolute value V of the interconnection point voltage of the renewable energy power source of the candidate for shedding before the fault is calculated using the various quantities of the candidate for shedding stored in the accelerator / shedding candidate data D223. m and calculate the phase angle average θ.

[0089] Next, in processing step S414, the composite impedance data D224 is used to proportionately divide the composite impedance so that the interconnection bus voltage phase of the renewable energy power source that is a candidate for power control becomes θ, based on the infinite bus in the one-machine infinite bus system.

[0090] A processing image of the simple system creation processing step S41 is shown in Fig. 20. The composite impedance data D224 is impedance data (jX) of a one-machine infinite bus system composed of an accelerator generator group SG and an infinite bus, as shown in the upper part of Fig. 20.

[0091] In contrast, in this invention, a simple system consisting of an accelerator generator group SG, a renewable energy power source group RES, and an infinite bus, as shown in the lower part of Figure 20, is assumed. This makes it possible to perform corrective control not only on the accelerator generator group SG but also on the renewable energy power source group RES. For this reason, the renewable energy power sources that are candidates for shedding control are aggregated and simulated into one unit using the method below, and added to the one-machine infinite bus system. Note that the various quantities such as voltage V, phase angle θ, power P, and impedance X of each part in the one-machine infinite bus system to which the candidate renewable energy power sources for shedding control have been aggregated and simulated into one unit are assumed to be as shown in the lower part of Figure 20.

[0092] First, the absolute average voltage V of one or more renewable energy sources that are candidates for power outages is calculated. m is calculated, for example, from equation (2).

[0093]

number

[0094] In equation (2), N is the number of renewable energy sources that are candidates for power control, and V N represents the absolute value of the voltage at the interconnection point of the Nth renewable energy source.

[0095] Similarly, the average phase angle θ of the interconnection point voltage of one or more renewable energy power sources that are candidates for power control is calculated using, for example, equation (3).

[0096]

number

[0097] Here, in equation (3), θ N represents the voltage phase angle at the interconnection point of the Nth renewable energy source. Note that the absolute average V m The method for calculating the phase angle average θ is not limited to equations (2) and (3). For example, the average value may be calculated by other methods such as a weighted average, a geometric average, or a harmonic average.

[0098] Next, the composite impedance X is apportioned according to the phase angle average θ. In a single-machine infinite-bus system, the voltage phase angle with respect to the infinite bus is determined by the magnitude of the impedance seen from the infinite bus. Because the pre-fault outputs of the acceleration synchronous machines and the renewable energy power source aggregated into one unit are known, the renewable energy power source can be added to the single-machine infinite-bus system by apportioning the composite impedance X to X1 and X2 so that the interconnection bus phase of the renewable energy power source is θ.

[0099] By including renewable energy power sources in the simplified grid as shown in the bottom of Fig. 20, the state quantities of the renewable energy power sources can be included in equation (6) for the power phase difference angle curve, which will be described later. This means that the power control and inverter characteristics of the renewable energy power sources can be taken into account when calculating the correction control amount.

[0100] A detailed flow of the power phase difference angle curve estimation process S42 is shown in Fig. 21. The procedure will be explained for each processing step in Fig. 21.

[0101] First, in processing step S421, the power phase difference angle curve before the first-stage control timing is estimated based on the post-measurement information of the acceleration synchronous machine and the renewable energy power source obtained from the synchronous machine / renewable energy measurement value data D412. Specifically, the oscillation equations (4) and (5) are solved using time-series data of the active power output of the acceleration synchronous machine before the first-stage control timing, obtained from the power system 100 after the fault has been cleared, to obtain Δω and Δδ.

[0102]

number

[0103]

number

[0104] Here, the parameters and constants in equations (4) and (5) are all equivalent values ​​of the accelerating synchronous machines aggregated into one unit, ω is the angular velocity, δ is the internal phase difference angle deviation before the fault, ω0 is the reference angular frequency, M is the inertia constant, P m is the mechanical input, P e represents the electrical output (active power output).

[0105] As will be described later with reference to Figures 23A and 23B, the power phase difference angle curve shows the deviation Δδ of the internal phase difference angle of the acceleration synchronous machine group from before the fault on the horizontal axis, and the effective power output P e Since this is a graph of the P e Using two-dimensional data consisting of a combination of Δδ calculated from equations (4) and (5), the power phase difference angle curve before the first stage control timing can be estimated.

[0106] Next, in processing step S422, the power phase difference angle curve after the first stage control timing is estimated based on the mathematical model data D413. Specifically, the ω and δ of the first stage control timing calculated based on the post-measurement information are used as initial values, and numerical integration of the fourth-order Runge-Kutta method is applied to equations (4) and (5) to calculate ω, δ, P after the first stage control timing. e In this case, P e is treated as a function of δ shown in equation (6).

[0107]

number

[0108] Equation (6) shows the power flow equation flowing from the acceleration synchronous machine group to the infinite bus in the simple system created by the simple system creation unit 41. Here, E is the absolute value of the equivalent transient reactance behind voltage of the acceleration synchronous machine group, V ∞ is the infinite bus voltage absolute value (presettling constant), X d ' is the transient reactance of the accelerating synchronous machine group, X t is the step-up transformer reactance, X ∞ is the transmission line reactance to the infinite bus. Also, I res , θ res , θ pf are all quantities related to the renewable energy power sources that are candidates for power control, and represent the output current, interconnection bus phase angle, and power factor angle, respectively.

[0109] The back voltage E in equation (6) is calculated by substituting the quantities before the fault into equation (7). The calculated value is treated as a constant value even after the fault occurs.

[0110]

number

[0111] Also, in equation (6), I res and θ res is found as a function of δ by solving the simultaneous equations (equation (6) and equations (8) to (11)). pf is a constant (presetting) based on the control mode of the renewable energy power source, and is included in the mathematical model data D413.

[0112]

number

[0113]

number

[0114]

number

[0115]

number

[0116] where P L is the active power flow from the interconnected bus of the renewable energy source to the infinite bus, P res is the active power output of the renewable energy source, V res represents the interconnection bus voltage of the renewable energy power source. In addition, A and B in equation (11) are both functions of δ and are expressed by equations (12) and (13), respectively.

[0117]

number

[0118]

number

[0119] However, P res and I res When calculating V, consider the constant power / constant current characteristics of the inverter of the renewable energy power source shown in Figure 22A. For example, if the current limiter of the renewable energy is 1.10 times the initial output, V calculated from equation (10) res When P is 0.91 pu or more res = 1.0 pu (constant) is applied to the above simultaneous equations, and V res If is less than 0.91 pu, I res =1.10 pu (constant) is applied.

[0120] In addition, if necessary, the dynamic output recovery characteristics of the renewable energy power source after the fault is cleared may be taken into consideration. For example, as shown in FIG. 22B, the output current I res If the output voltage recovers at a ramp rate after the fault is cleared, the time is t and the output current before the fault is I res、0 , the fault removal time is t cl , the time required for output recovery is T rrThen, I res can be expressed by equation (14).

[0121]

number

[0122] As described above, by taking the inverter characteristics of the renewable energy power source into consideration in the power phase difference angle curve, it is expected that the accuracy of calculating the correction control amount will be improved.

[0123] Returning to FIG. 21 again, in processing step S423, the equal area method is applied to the estimated power phase difference angle curve to obtain the acceleration energy E A and deceleration energy E D Calculate.

[0124] 23A and 23B show the acceleration energy E A and deceleration energy E D Fig. 23A shows the power phase difference angle curve when an acceleration synchronous machine is controlled using first-stage control, and Fig. 23B shows the power phase difference angle curve when a renewable energy power source is controlled using first-stage control.

[0125] Using the equal area method, the acceleration energy E A is the mechanical input P m and is calculated from the area enclosed by the power phase difference angle curve from before the fault to the first stage control timing. D is the mechanical input P m and is calculated from the area enclosed by the power phase difference angle curves after the first stage control.

[0126] In addition, the acceleration energy E A Instead of being calculated from Figures 23A and 23B, it may be calculated as the kinetic energy of the accelerating synchronous machine group at the first stage control timing. In this case, the acceleration energy E A is expressed by equation (15).

[0127]

number

[0128] where M' is the inertia constant of the acceleration synchronous machine group that is not the first stage control target, Δω p is the angular velocity deviation of the accelerating synchronous machine group at the first stage control timing.

[0129] In the equal area method, the deceleration energy E D is the acceleration energy E A In the above cases, the power system can be judged as transiently stable. Therefore, E D The increasing effect represents their stabilizing effect.

[0130] As shown in Figure 23A, when some of the acceleration synchronous machines are powered down by the first stage control, the parallel capacity of the acceleration synchronous machines is reduced, so the transient reactance X d ' and step-up transformer reactance X t Therefore, the power phase difference angle curve after the first stage control is -P e However, the mechanical input P m HA P m ', resulting in a deceleration energy E D increases before and after the power control of the acceleration synchronous machine group.

[0131] In addition, when a part of the renewable energy power source is controlled by the first stage control as shown in Figure 23B, the output P res Since the output current I res As a result, from equation (6), the power phase difference angle curve after the first stage control is +P e The trajectory is like a parallel movement in the direction. Therefore, the deceleration energy E D increases before and after the shutdown of renewable energy sources.

[0132] As is clear from Figures 23A and 23B, in both cases, the deceleration energy E D increases before and after the shedding of an accelerating synchronous machine and a renewable energy power source. The mechanisms and mechanisms that generate deceleration energy at this time are different, but in either case, it can be calculated using equation (6). This means that the power phase difference angle curve after shedding has been estimated.

[0133] The stabilization effect described above can be evaluated not only for first-stage control but also for corrective control that is performed later than first-stage control. When both the acceleration synchronous machines and the renewable energy power source are controlled by first-stage control or corrective control, the E in both Figures 23A and 23B D The increasing effect appears.

[0134] As mentioned above, in the power phase difference angle curve estimation, the effective power output P e is the output current I of the renewable energy power source. res By expressing it as a function of E, it is possible to control not only the acceleration synchronous machine group but also the renewable energy power source. D Since the effect of increase can also be evaluated, renewable energy sources can be included in the targets of correction control.

[0135] Next, a detailed flow of the correction control target selection processing step S44 is shown in Fig. 24. The correction control target selection processing step S44 is performed in the stability determination processing step S43 by using the acceleration energy E A and deceleration energy E D Compare E A >E D This is a process that becomes necessary when the following is true: The procedure for correction control will be explained for each processing step in FIG.

[0136] First, in processing step S441, one generator with the highest power control selection priority, excluding the first-stage control target, is selected based on the power control selection priority data D226.

[0137] Next, in process step S442, a power phase difference angle curve for corrective control of the generator selected in process step S441 is estimated, and deceleration energy ED is recalculated in the same manner as described with reference to FIG.

[0138] Next, in processing step S443, the acceleration energy EA calculated in the power phase difference angle curve estimation processing S42 and the deceleration energy E recalculated in processing step S442 are D If it is stable ("YES" in processing step S443), the process proceeds to processing step S444, which will be described later. If it is unstable ("NO" in processing step S443), the process returns to processing step S441, and an additional correction control target is selected.

[0139] Next, in processing step S444, all the generators selected in processing step S441 are determined to be objects of corrective control, and are transmitted to the control unit 5. The control unit 5 transmits a power control command to each object of corrective control.

[0140] Next, an example of the results displayed by the display unit 6 will be described with reference to Fig. 25. In the "Search Settings" field in Fig. 25, the time and fault conditions for which the results of the shedding machine selection are to be displayed are set.

[0141] In the "Power System Diagram" column of Figure 25, the first-stage control target data D226 and the corrective control target data D424 are displayed in a power system diagram, along with the names of the targets of power control and their total power control amounts. In addition to the fault locations, this system diagram also displays generators connected to the system, distinguishing between those subject to first-stage control, those subject to corrective control, and those not subject to power control. In addition, acceleration synchronous machines and candidates for power control may also be shown on the system diagram. This allows power system operators and planners to easily understand the relative positions of anticipated faults, targets of power control, and acceleration synchronous machines.

[0142] In the "Post-calculation result" column of FIG. 25, the power phase difference angle curve data D422 and the stability determination result data D423 are displayed in the form of a graph or a table. This allows the operator or planner of the power system to check the stability determination results of the transient stability before and after the correction control and the basis for the determination (acceleration energy E A and deceleration energy E DIt is possible to easily check the relationship between the magnitudes of the

[0143] Figure 26 shows the effect of the present invention on the stability of a power system. In Figure 26, the difference in transient stability (whether or not a synchronous machine loses synchronism) depending on whether or not correction control is applied is shown by the internal phase difference angle waveform of the synchronous machine. In the case without correction control (first stage control only) shown on the left side of Figure 26, transient stability cannot be stabilized, but it can be stabilized by implementing the correction control of the present invention shown on the right side of Figure 26.

[0144] In the above-described embodiment, the master station 2 and the slave station 4 are provided, and the functions of the master station 2 and the slave station 4 are shared to perform first-stage control and correction control. However, various system configurations can be adopted. Everything can be instructed by the master station 2, or everything can be determined by the slave station. Even if the functions are shared, the extent of the sharing can be determined taking into consideration appropriate circumstances. In short, it is sufficient if the system can perform first-stage control based on a pre-planned plan, as well as corrective control taking into account the system status after the fact, and can determine the amount of correction control based on an estimated power phase difference angle curve including renewable energy power sources during corrective control.

[0145] The power system stabilization device of the present invention described above is, in short, "a power system stabilization device that performs first-stage control to cut off power at the time of a fault of one or more of the synchronous machine SG and the renewable energy power source RES based on a pre-calculation of stability at the time of an assumed fault in a power system including the synchronous machine SG and the renewable energy power source RES, and performs corrective control to perform additional cutoff power based on a post-calculation at the time of a fault if the amount of cutoff power is insufficient in the first-stage control, wherein a post-calculation unit 40 that performs the post-calculation at the time of a fault comprises: a simple system creation unit 41 that creates a simple system model consisting of the accelerating synchronous machine SG and the renewable energy power source RES based on the results of the pre-calculation and fault information; a power phase angle curve estimation unit that applies the post-measurement information at the time of the fault to the simple system model to estimate a power phase angle curve that shows the relationship between power and phase angle in the power system when additional cutoff power by the accelerating synchronous machine SG and the renewable energy power source RES is implemented; and a corrective control target selection unit 44 that selects one or more of the accelerating synchronous machine SG and the renewable energy power source RES as targets for additional cutoff power based on the estimation result of the power phase angle curve in the power phase angle curve estimation unit."

[0146] According to the above-described embodiment of the present invention, the stabilizing effect of power control on synchronous generators and renewable energy power sources can be evaluated, and corrective control of the synchronous generators and renewable energy power sources can be performed based on the evaluation results. This makes it possible to maintain transient stability even in power systems with a high proportion of renewable energy power sources, and to reduce the total amount of power control required to maintain transient stability (the cost required to recover from power control). [Example]

[0147] In Example 1, the output characteristics of each renewable energy power source are modeled in advance using a single preset pattern, and a common power control selection order for first-stage control and correction control is calculated from the results of a numerical simulation using this.

[0148] However, there are many uncertainties in the output characteristics of renewable energy power sources in the event of a failure. In particular, because a large number of small-scale renewable energy power sources are connected to high- and low-voltage systems, it is difficult for power system operators and planners to accurately predict their output characteristics through advance calculations.

[0149] Furthermore, the output characteristics of renewable energy power sources during a fault are affected by their normal output. Therefore, if a fault occurs in a system where the output of a renewable energy power source fluctuates between pre-calculation cycles, the output characteristics of the renewable energy power source assumed in the pre-calculation may not match the actual phenomenon.

[0150] Because the output characteristics of renewable energy power sources during failures affect the stability of the power grid, the above miscalculation could make it difficult to stabilize the grid through corrective control, or could increase the amount of corrective control required for stabilization.

[0151] Therefore, the power system stabilization device 1 of the second embodiment addresses the above-mentioned problem by calculating the power control selection order for each of the multiple assumed patterns of output characteristics of the renewable energy power source in advance in the parent station 2, and then switching the power control selection order for the correction control according to the output of the renewable energy power source estimated from the system measurement data after a failure.

[0152] 27 shows an example of the functional configuration of the power system stabilizing device 1 of the second embodiment. In the various data and calculation units, elements that are different from those of the first embodiment are written in bold.

[0153] 28 shows an example of the hardware configuration of the power system stabilizing device 1 of the second embodiment. In various input / output data, elements that are different from those in the first embodiment are written in bold.

[0154] 29 shows a group of programs held in the program database DB50 in the second embodiment. The difference from the first embodiment is that a pattern generation target extraction program Pr10, a renewable energy output amount estimation program Pr11, and a renewable energy output amount performance calculation program Pr12 are included. Note that the following explanation will mainly focus on the newly added parts or the parts that have been changed due to the addition.

[0155] Here, the newly added databases DB217 to DB218 that constitute the pre-computation input data D21 of the second embodiment will be described.

[0156] The first-stage control stabilization cross section database DB217 stores data such as the transient stability calculation results under conditions for power control of the first-stage control target calculated by the parent station 2, the system cross section used in the calculation, and the system model. In addition, the renewable energy output characteristic pattern database DB218 stores data such as setting values ​​of multiple output characteristic patterns of renewable energy power sources. Images of the renewable energy output characteristic pattern data D218 are shown in Figures 30A, 30B, and 30C.

[0157] If a fault occurs in the power grid and the interconnection bus voltage of a renewable energy power source drops significantly, the inverter installed in the renewable energy power source has the function of temporarily halting output to prevent equipment failure due to abnormal voltage, and then restoring output after the fault is cleared.

[0158] As an example of this recovery characteristic, consider the three patterns shown in Figures 30A, 30B, and 30C. Figures 30A, 30B, and 30C are all graphs with time on the horizontal axis and the output current of the renewable energy power source on the vertical axis. Figure 30A shows a pattern in which the output instantly returns to the pre-fault level upon fault clearance. Figure 30B shows a pattern in which the output returns to the pre-fault level at a ramp rate at a preset time T1 after fault clearance. Figure 30C shows a pattern in which the output does not return to the pre-fault level after fault clearance. The renewable energy output characteristic pattern database DB218 includes the required time T1 for ramp rate recovery in the pattern shown in Figure 30B, as well as setting value data required for modeling the patterns shown in Figures 30A, 30B, and 30C. Note that the number of output characteristic patterns may be set to a number other than three. Also, output characteristics different from those shown in Figures 30A, 30B, and 30C may be present.

[0159] Next, the processing of the pre-calculation unit 20 in the second embodiment will be described with reference to Fig. 31. This processing is executed after the first-stage controlled object calculation in each cycle during normal operation of the power system 100. The flow of the calculation processing will be described for each processing step.

[0160] First, in processing step S27, a renewable energy power source for which multiple output characteristic patterns are to be modeled is extracted using the pattern generation target extraction program Pr10, and pattern generation target data D227 is output. For example, the extraction method is to extract renewable energy power sources for which the residual voltage ratio of the interconnection bus during a fault is below 20%, or for which the power generation output during the fault is less than 20% of the power generation output before the fault. Hereinafter, the extracted renewable energy power source will be referred to as a pattern generation target renewable energy.

[0161] Next, in processing step S22, the output characteristics of the renewable energy for which patterns are to be generated are modeled using multiple patterns defined in the renewable energy output characteristic pattern data D218. Then, the transient stability calculation program Pr2 is executed for each modeling, and stability calculation result data D222 is output.

[0162] Next, in processing step S28, the renewable energy output amount estimation program Pr11 is executed on the stability calculation result data D222, the output amount of the renewable energy for which a pattern is to be generated after a fault is cleared is calculated for each output characteristic pattern, and renewable energy output amount estimation data D228 is output. The output amount is calculated, for example, as the time integral value of the active power output of the renewable energy for which a pattern is to be generated for T2 milliseconds from the timing of the fault clearance. Note that if there are multiple renewable energy for which patterns are to be generated, the total output amount of each renewable energy for which a pattern is to be generated is calculated.

[0163] Next, in processing step S25, the shedding control selection setting data D216, the stability calculation result data D222, and the accelerator / shedding control candidate data D223 are used to execute the shedding control selection order calculation program Pr5, and output shedding control selection order data D226. At this time, the shedding control selection order for each output characteristic pattern is linked to the output amount estimation result for each output characteristic pattern in the renewable energy output amount estimation data D228.

[0164] The process steps S28 and S25 are executed regardless of whether the stability calculation result of the process step S22 is stable or unstable.

[0165] Next, the processing of the post-calculation unit 40 in the second embodiment will be described with reference to Fig. 32. This processing is executed when a fault actually occurs in the power system 100. The processing contents of processing steps S41 to S43 are the same as those in the first embodiment, so the processing from processing step S45 onwards will be described below.

[0166] First, in processing step S45, the actual output amount of the renewable energy for which a pattern is to be generated after the fault is removed is calculated using the synchronous machine / renewable energy measurement value data D412 and the pattern generation target data D227, using the renewable energy output amount actual calculation program Pr12, and the renewable energy output amount actual data D425 is output.

[0167] Next, in processing step S44, the renewable energy output amount estimation data D228 and the power control selection order data D226 are used to adopt the power control selection order in which the result of the advance estimation of the output amount is closest to the actual value calculated in processing step S45. Then, the power control selection order thus adopted is used to execute the corrected control target selection program Pr9, output the corrected control target data D424, and end the processing.

[0168] Here, a process image of the renewable energy output amount actual calculation unit 45 and the correction control target selection unit 44 is shown in FIG.

[0169] In Figure 33, a, b, and c show the processing flow from the post-measurement data of the renewable energy source for which the pattern is generated to determining the power control selection order for the correction control.

[0170] First, in step a, the output change of the renewable energy source for which a pattern is to be generated after a failure is estimated based on the synchronous machine / renewable energy measurement value data D412.

[0171] Next, in step b, the time integral value of the output for T2 milliseconds from the fault clearance is calculated as the actual output amount for the output data of the renewable energy source for which the pattern was generated estimated in step a. If there are multiple renewable energy sources for which the pattern was generated, the total output amount of each renewable energy source for which the pattern was generated is calculated.

[0172] Next, in step c, the output amount of each output characteristic pattern estimated in the pre-calculation is compared with the actual output amount calculated in step b, and the output characteristic pattern with the smallest error from the actual output amount is adopted as the shedding control selection priority. In the example of the table in Figure 33, the output characteristic pattern (Figure 30B) has the smallest difference between the post-facto actual output amount and the pre-estimate, so the shedding control selection priority calculated for the output characteristic pattern (Figure 30B) is adopted in the correction control.

[0173] By using Example 2, it is possible to select the power control selection order for correction control that is suitable for the actual phenomenon of the output characteristics of the renewable energy power source, and therefore it is expected that the amount of correction control required for stabilization can be reduced compared to using the power control selection order that is common to the first stage control for correction control.

[0174] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations. Furthermore, part or all of the above-described configurations, functions, processing units, etc. may be realized in hardware, for example, by designing them as integrated circuits. [Explanation of symbols]

[0175] 1: Power system stabilizer 2: Master station 3: Communications Department 4: Slave station 5: Control unit 6: Display section 7: Input section 8: Processor 9: Memory 10: Bus line 20: Pre-calculation section 21:Analysis section creation part 22: Transient stability calculation section 23: Acceleration synchronous machine / Electrification control candidate extraction part 24: Synthetic impedance calculation unit 25: Power control selection order calculation section 27: Pattern generation target extraction unit 28: Renewable energy output estimation unit 40: Post-operation section 41: Simple System Creation Department 42: Power phase difference angle curve estimator 43: Stability determination section 44: Correction control target selection unit 45: Renewable energy output performance calculation section 30a, 30b: Measuring device 100: Power system 110a-110c: Synchronous generators and renewable energy sources 120a~120c, 121a~121c: Node (bus line) 130a~130c: Transformers 140a~140c: Branch (railway) 200: Communication Network D21: Pre-calculated input data D22: Pre-calculated output data D41: Post-calculation input data D42: Post-calculation output data D211: System configuration data DB211: System configuration database D212: System measurement data DB212: System measurement data database D213: System model data DB213: System model database D21: List of expected failures DB214: Contingency list database D215: Threshold data DB215: Threshold database D216: Electronic control selection setting data DB216: Electric control selection setting database D217: First stage control stabilization cross section data DB217: First stage control stabilization cross section database D218: Renewable energy output characteristic pattern data DB218: Renewable energy output characteristic pattern database D221: Analysis cross-sectional data DB221: Analysis cross section database D222: Stability calculation result data DB222: Stability calculation results database D223: Accelerator and electrical control candidate data DB223: Accelerator and power control candidate database D224: Synthetic impedance data DB224: Synthetic Impedance Database D225: First stage control target data DB225: First-stage control object database D226: Electric control selection order data DB226: Electric control selection order database D227: Pattern generation target data DB227: Pattern generation target database D228: Renewable energy output estimation data DB228: Renewable energy output estimation database D411: Malfunction information data DB411: Malfunction information database D412: Synchronous machine and renewable energy measurement data DB412: Synchronous Machine and Renewable Energy Measurement Data Database D413: Mathematical Model Data DB413: Mathematical Model Database D421: Simple system data DB421: Simple genealogy database D422: Power phase difference angle curve data DB422: Power Phase Angle Curve Database D423: Stability determination result data DB423: Stability determination result database D424: Correction control target data DB424: Correction control target database D425: Actual renewable energy output data DB425: Renewable energy output performance database DB50: Program Database Pr1: Analysis cross section creation program Pr2: Transient stability calculation program Pr3: Acceleration synchronous machine and electrical control candidate extraction program Pr4: Synthetic impedance calculation program Pr5: Power control selection order calculation program Pr6: Simple system creation program Pr7: Power phase difference angle curve estimation program Pr8: Stability determination program Pr9: Correction control target selection program Pr10: Pattern generation target extraction program Pr11: Renewable energy output estimation program Pr12: Renewable energy output calculation program

Claims

1. A power system stabilization device that performs first-stage control to control power supply to one or more of the synchronous machine and the renewable energy power source at the time of a contingent failure based on a pre-calculation of stability at the time of a contingent failure in a power system including the synchronous machine and the renewable energy power source, and performs correction control to additionally control power supply based on a post-calculation at the time of a failure when the amount of power supply control is insufficient in the first-stage control, a power phase difference angle curve estimation unit that estimates a power phase difference angle curve that indicates the relationship between power and phase difference angle in the power system when additional power control by the acceleration synchronous machine and the renewable energy power source is implemented by applying the post-measurement information at the time of the failure to the simple system model; and a correction control target selection unit that selects one or more types of additional power control targets from the acceleration synchronous machine and the renewable energy power source based on the estimation result of the power phase difference angle curve by the power phase difference angle curve estimation unit.

2. 2. The power system stabilization device according to claim 1, the power phase difference angle curve estimation unit uses a state quantity of the renewable energy power source as the ex-post measurement information at the time of the failure, and the state quantity of the renewable energy power source is one or more of an output current, an active power output, an interconnection bus voltage, an interconnection bus voltage phase angle, and a power factor angle of the renewable energy power source.

3. 2. The power system stabilization device according to claim 1, The power system stabilization device, characterized in that the results of the pre-calculation include data on acceleration synchronous machines and shearing control candidates in the event of a contingent fault in the power system, data on the impedance of the power system, data on first-stage control targets, and shearing control selection priority data.

4. 2. The power system stabilization device according to claim 1, The power system stabilization device, wherein the post-fault measurement information includes information on the active power output of the accelerating synchronous machine and the renewable energy power source after a fault occurs in the power system.

5. 2. The power system stabilization device according to claim 1, A power system stabilization device characterized in that a target of said first stage control is calculated in advance in a master station before a fault occurs, and a target of said correction control is calculated in a slave station after the fault occurs.

6. 2. The power system stabilization device according to claim 1, The simplified system model is a power system stabilization device characterized in that it is composed of an acceleration synchronous machine group in which one or more acceleration synchronous machines are aggregated into one unit, a renewable energy power source group in which one or more renewable energy power sources that are candidates for power control are aggregated into one unit, an infinite bus that is a bus whose voltage and voltage phase angle are always constant, and transmission lines and transformers that connect these.

7. 7. The power system stabilization device according to claim 6, The power system stabilization device is characterized in that the interconnection bus voltage of the group of renewable energy power sources is calculated using one or more of an arithmetic mean, a weighted mean, a geometric mean, or a harmonic mean of the interconnection bus voltages of each renewable energy power source before aggregation.

8. 7. The power system stabilization device according to claim 6, a power system stabilization device, characterized in that the voltage phase angle of the interconnection bus of the group of renewable energy power sources is calculated using one or more of an arithmetic mean, a weighted mean, a geometric mean, or a harmonic mean of the voltage phase angles of the interconnection bus of each renewable energy power source before aggregation.

9. 2. The power system stabilization device according to claim 1, a power system stabilization device, wherein the power phase difference angle curve is expressed by a power flow equation of active power flowing from a group of acceleration synchronous machines in which one or more acceleration synchronous machines are aggregated into one machine toward an infinite bus;

10. 7. The power system stabilization device according to claim 6, The power system stabilization device is characterized in that the group of renewable energy power sources has a constant current characteristic that keeps the output current constant when the interconnection bus voltage is equal to or less than a preset value, and a constant power characteristic that keeps the power generation output constant when the interconnection bus voltage exceeds the preset value.

11. 2. The power system stabilization device according to claim 1, the correction control target selection unit selects a correction control target in accordance with a power control selection priority calculated in advance until a deceleration energy value of an accelerating synchronous machine calculated using the simplified system model becomes equal to or greater than an acceleration energy value of the accelerating synchronous machine.

12. 2. The power system stabilization device according to claim 1, The power system stabilization device is characterized in that the pre-calculation involves modeling multiple patterns of output characteristics of some of the renewable energy power sources after a first-stage control object calculation, and calculating a power control selection order and an estimated output amount of the some of the renewable energy power sources for each modeling using a result of the first-stage control object calculation.

13. 13. The power system stabilization device according to claim 12, The power system stabilization device is characterized in that the part of the renewable energy power source is extracted based on the voltage and power generation output during the failure calculated when calculating the target of first stage control.

14. 13. The power system stabilization device according to claim 12, The power system stabilization device, characterized in that the output amount estimate value is obtained by time integration of the active power output of the part of the renewable energy power source over a predetermined time range after the occurrence of a fault in a numerical simulation of stability performed for each of the modeling.

15. 13. The power system stabilization device according to claim 12, A power system stabilization device comprising: a renewable energy output amount actual calculation unit that calculates an actual output amount value of the part of renewable energy power sources using measurement information related to the active power output of the part of renewable energy power sources after a failure occurs.

16. 16. The power system stabilization device according to claim 15, the correction control target selection unit selects a power control selection priority to be used for selecting a correction control target from among a plurality of power control selection priorities determined by pre-calculation, based on a comparison between the estimated output amount value and the actual output amount value.

17. 2. The power system stabilization device according to claim 1, comprising an output unit, the output unit comprises a display unit that displays at least one of system configuration data, system measurement value data, system model data, contingent fault list data, threshold value data, shearing control selection setting data, shearing control selection setting data, accelerator / shearing control candidate data, synthetic impedance data, first-stage control object data, shearing control selection ranking data, fault information data, synchronous machine / renewable energy measurement value data, mathematical model data, simplified system data, power phase difference angle curve data, stability determination result data, corrected control object data, first-stage control stabilization cross section data, renewable energy output characteristic pattern data, pattern generation object data, renewable energy output amount estimation data, and renewable energy output amount actual data.

18. A power system stabilization method using a computer to implement a process of performing a first-stage control to control power supply to one or more of the synchronous machine and the renewable energy power source at the time of a contingent fault based on a pre-calculation of stability at the time of a contingent fault in a power system including the synchronous machine and the renewable energy power source, and performing a correction control to additionally control power supply based on a post-calculation at the time of the fault if the amount of power supply control is insufficient in the first-stage control, The power system stabilization method is characterized in that the post-calculation by the computer at the time of the fault creates a simple system model consisting of an accelerating synchronous machine and a renewable energy power source based on the result of the pre-calculation and fault information, applies the post-measurement information at the time of the fault to the simple system model to estimate a power phase difference angle curve that shows the relationship between the power and phase difference angle of the power system when additional power control is implemented by the accelerating synchronous machine and the renewable energy power source, and selects one or more types of additional power control targets from among the accelerating synchronous machine and the renewable energy power source based on the estimated result of the power phase difference angle curve.

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