System stabilization system and system stabilization method

Abstract

To provide a selection method of an electric control object which can preferentially make a renewable energy power generation device into the electric control object and realize effective system stabilization.SOLUTION: There is provided a system stabilization system comprising a central processing unit 20 of an online type pre-calculation system. A pre-calculation unit 50 of the central processing unit 20 first determines a renewable energy power generation device for electric control from among electric control object candidates in a priority order based on a first evaluation index (formula 3) and determines a synchronous motor for electric control from among the electric control object candidates so that the entire electric control amount becomes small as much as possible on the basis of a priority order based on a second evaluation index (formula 2) when a stability calculation result is not stabilized. The second evaluation index is the total sum of output variation to be generated in each synchronous motor of the electric control object candidates by interruption of the power generator for electric control, and the first evaluation index is a value obtained by dividing the second evaluation index by the electric control amount of a motor for electric control.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a system stabilization system and a system stabilization method.

Background Art

[0002] A system stabilization system aimed at maintaining the synchronous stability of a power system disconnects some generators from the power system (also referred to as "shutdown" or "power curtailment") in order to prevent generator out-of-step when a system accident occurs.

[0003] Typical system stabilization systems in Japan include the ISC (Integrated Stability Control) system of Chubu Electric Power. In these systems, power curtailment of synchronous generators is used as a means to maintain synchronous stability, and renewable energy power generation devices are not subject to power curtailment.

[0004] As a system stabilization system that treats both synchronous generators and renewable energy power generation devices as objects of power curtailment, for example, a system stabilization system disclosed in Japanese Patent Application Laid-Open No. 2021-141790 (Patent Document 1) is known. In the system stabilization system of this document, "the central arithmetic unit performs a transient stability calculation when power curtailment is performed on a power curtailment candidate, and using the transient stability calculation result, represents it in a two-machine system model of a synchronous machine group G1 with an unstable tendency of synchronous stability and a synchronous machine group G2 with a stable tendency, converts the two-machine system model into a one-machine infinite bus model, and divides the amount by which the change rate of the angular velocity deviation of the synchronous generator in the one-machine infinite bus model decreases at the time of power curtailment implementation by the power curtailment amount, and uses the obtained value as an index representing the stabilization effect, and selects the power curtailment candidate with the maximum index as the power curtailment target" (see the summary of Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the index representing the stabilization effect of the above Patent Document 1, since the synchronous generator has a higher stabilization effect than the renewable energy power generation device, the synchronous generator is more likely to be preferentially selected as the power control target.

[0007] However, the synchronous generator has a problem that it is more burdensome to reconnect to the power grid after being disconnected from the power grid than the renewable energy power generation device. For example, when controlling the synchronous generator, it is necessary to stop devices such as boilers and turbines in addition to the generator, and it takes time to restart these devices. On the other hand, wind power generation devices and solar power generation devices, which are typical renewable energy power generation devices, can basically be reconnected to the power grid only by opening and closing the switching device.

[0008] The present disclosure has been made in consideration of the above background art, and one of its purposes is to provide a system stabilization system that preferentially selects a renewable energy power generation device as the power control target and selects the power control target so as to achieve effective system stabilization.

Means for Solving the Problems

[0009] A system stabilization system according to an embodiment includes a plurality of terminal devices, a post-control unit, and a pre-calculation unit. Each of the plurality of terminal devices is associated with one of a plurality of generators including a synchronous generator and a renewable energy power generation device, and shuts off the corresponding generator from the power grid according to a shut-off command. The post-control unit transmits a shut-off command to the terminal device corresponding to the generator to be controlled electrically according to a control table when an accident occurs in the power grid. The pre-calculation unit creates in advance a control table in which the generator to be controlled electrically is associated with an assumed accident by performing a stability calculation for each assumed accident. The pre-calculation unit includes a power control candidate selection unit and a power control target determination unit. The power control candidate selection unit selects a plurality of synchronous generators and a plurality of renewable energy power generation devices that are candidates for the power control target based on the result of the stability calculation. The power control target determination unit determines a renewable energy power generation device to be the power control target from among the power control target candidates in the order of priority based on a first evaluation index, and when the stability calculation result does not become stable even if all the renewable energy power generation devices of the power control target candidates are controlled electrically, determines a synchronous generator to be the power control target from among the power control target candidates so that the total amount of power control becomes as small as possible based on the order of priority based on a second evaluation index. The first evaluation index for the p-th renewable energy power generation device among the renewable energy power generation devices of the power control target candidates is a value obtained by dividing the sum of the output change amounts of the respective synchronous generators of the power control target candidates when the p-th renewable energy power generation device is controlled electrically by the amount of power control of the p-th renewable energy power generation device. The second evaluation index for the q-th synchronous generator among the synchronous generators of the power control target candidates is the sum of the output change amounts of the respective synchronous generators of the power control target candidates excluding the q-th when the q-th synchronous generator is controlled electrically.

Advantages of the Invention

[0010] According to the above embodiment, it is possible to preferentially set the renewable energy power generation device as the power control target and select the generator to be the power control target so that effective system stabilization can be achieved by using the first evaluation index and the second evaluation index.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Best Mode for Carrying Out the Invention

[0012] Hereinafter, each embodiment will be described in detail with reference to the drawings. In addition, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

[0013] Embodiment 1. [Overall Configuration of Power System and System Stabilization System] FIG. 1 is a diagram conceptually showing a part of the configuration of a power system 2 in which a system stabilization system 1 is installed. In FIG. 1, as a part of the configuration of the power system 2, transmission lines PL1 and PL2, buses BL1 to BL3, synchronous generators SG1 to SG3, a solar power generation device PV1, and a wind power generation device WT1 are typically shown.

[0014] As shown in FIG. 1, each of the synchronous generators SG1 to SG3 is connected to the bus BL1 via the corresponding transformer among the transformers TR1 to TR3 and the corresponding circuit breaker among the circuit breakers CB1 to CB3. The solar power generation device PV1 is connected to the bus BL2 via a power converter PC1 and a circuit breaker CB4. The wind power generation device WT1 is connected to the bus BL3 via a transformer TR4 and a circuit breaker CB5.

[0015] In addition, a large number of synchronous generators, solar power generation devices, and wind power generation devices are also provided in other parts 3 of the power system 2. In the following description, when collectively referring to the synchronous generators, solar power generation devices, and wind power generation devices provided in the power system 2, they are described as synchronous generator SG, solar power generation device PV, and wind power generation device WT, respectively. Also, when collectively referring to circuit breakers, they are described as circuit breaker CB, when collectively referring to transformers, they are described as transformer TR, and when collectively referring to power converters, they are described as power converter PC.

[0016] The system stabilization system 1 includes a central arithmetic unit 20 and a plurality of terminal devices 30A to 30C. The central arithmetic unit 20 and each terminal device 30 are interconnected via a wired and / or wireless communication line 40. Note that a large number of terminal devices are also provided in other parts 3 of the power system 2, and the central arithmetic unit 20 is interconnected with these terminal devices via the communication line 40. In the following description, the terminal devices provided in the power system 2 are collectively referred to as terminal device 30.

[0017] The central arithmetic unit 20 is further connected to the central power supply command post 10 via a communication line 42. The central power supply command post 10 predicts the power demand that changes every moment and outputs a command to adjust the power generation amount of each generator (synchronous generator and renewable energy power generation device). The functions of the central arithmetic unit 20 will be described later with reference to FIG. 3.

[0018] Each terminal device 30 is connected to a corresponding voltage transformer VT and a corresponding current transformer CT provided in the power system 2 to detect voltage values and current values. When a system accident occurs, each terminal device 30 determines the accident point and accident type based on the detected voltage values and current values, and transmits information regarding the determined accident point and accident type to the central arithmetic unit 20. Further, each terminal device 30 outputs a trip signal to the corresponding circuit breaker CB based on a cutoff command from the central arithmetic unit 20.

[0019] Specifically, in the case of FIG. 1, the terminal device 30A detects the voltage value of the bus bar BL1 using the voltage transformer VT1, and detects the current values of the power transmission lines PL1 and PL2 using the current transformers CT1 and CT2, respectively. Further, the terminal device 30A shuts off the synchronous generator SG1 by outputting a trip signal to the circuit breaker CB1, shuts off the synchronous generator SG2 by outputting a trip signal to the circuit breaker CB2, and shuts off the synchronous generator SG3 by outputting a trip signal to the circuit breaker CB3.

[0020] Similarly, the terminal device 30B detects the voltage value of the bus bar BL2 using the voltage transformer VT2, and detects the current values of the power transmission lines PL1 and PL2 using the current transformers CT3 and CT4, respectively. Also, the terminal device 30B detects the current value of the power transmission line from the bus bar BL2 to the power converter PC1 using the current transformer CT5. Further, the terminal device 30B shuts off the solar power generation device PV1 by outputting a trip signal to the circuit breaker CB4.

[0021] Similarly, the terminal device 30C detects the voltage value of the bus bar BL3 using the voltage transformer VT3, and detects the current value of the power transmission line from the bus bar BL3 to the transformer TR4 using the current transformer CT6. Further, the terminal device 30C shuts off the wind power generation device WT1 by outputting a trip signal to the circuit breaker CB5.

[0022] [Hardware Configuration Example of Terminal Device and Central Processing Unit] FIG. 2 is a block diagram showing an example of the hardware configuration of each terminal device and the central processing unit in FIG. 1.

[0023] (1. Hardware Configuration Example of Terminal Device) Referring to FIG. 2, the terminal device 30 includes auxiliary transformers 31_1, 31_2, … (collectively referred to as auxiliary transformer 31 when generalized), analog filters (AF: Analog Filter) 32_1, 32_2, … (collectively referred to as analog filter 32 when generalized), an A / D converter 33, a processing circuit 34, a communication circuit 35, a digital output (DO: Digital Output) circuit 36, and a digital input (DI: Digital Input) circuit 37. The auxiliary transformer 31 is also referred to as an input transformer.

[0024] The terminal device 30 is provided with a plurality of channels for receiving the current signals of each phase output from the corresponding current transformer CT and the voltage signals of each phase output from the corresponding voltage transformer VT. Each channel receives the current signal of each phase and the current signal of each phase from the corresponding current transformer CT, respectively. In FIG. 2, only two channels are typically shown.

[0025] The auxiliary transformers 31 (31_1, 31_2, …) are provided for each channel. Each auxiliary transformer 31 receives a current signal from the current transformer CT or a voltage signal from the voltage transformer VT, and converts the received voltage signal or current signal into a signal with a voltage level suitable for signal processing in the A / D converter 33 and the processing circuit 34.

[0026] The analog filters 32 (32_1, 32_2, …) are provided for each channel corresponding to a plurality of auxiliary transformers 31 respectively. Each analog filter 32 is, for example, a low-pass filter that cuts the high frequency of the current signal or voltage signal of the corresponding channel. The analog filter 32 is provided to remove the aliasing error during A / D conversion.

[0027] The A / D converter 33 converts the analog current signal or voltage signal output from each analog filter 32 into a digital value. The A / D converter 33 may include a sample-and-hold circuit (not shown) and a multiplexer (not shown) for each channel. In this case, the multiplexer sequentially selects the electrical quantity signals held in the sample-and-hold circuit, and the A / D converter 33 performs A / D conversion on the signals selected by the multiplexer.

[0028] In the case of this embodiment, the processing circuit 34 is configured as a microcomputer including at least one CPU (Central Processing Unit), at least one RAM (Random Access Memory), and at least one non-volatile memory. In this case, the CPU realizes a desired function according to the control program stored in the non-volatile memory. The control program may be provided as a non-transitory storage medium or may be provided via a network.

[0029] Note that the processing circuit 34 may be configured as at least one FPGA (Field Programmable Gate Array), or may be configured as a dedicated circuit such as at least one ASIC (Application Specific Integrated Circuit). Alternatively, the processing circuit 34 may be configured by any combination of a CPU, an FGPA, and an ASIC.

[0030] The communication circuit 35 transmits and receives data to and from the communication circuit 21 of the central processing unit 20 via the communication line 40.

[0031] The digital output circuit 36 is an interface circuit for outputting a digital signal to an external device. For example, the digital output circuit 36 outputs a trip signal to the corresponding circuit breaker CB according to a command from the processing circuit 34.

[0032] The digital input circuit 37 is an interface circuit for receiving the input of digital signals from an external device. For example, the digital input circuit 37 receives information on the open / closed state of the contacts of the circuit breaker CB from the circuit breaker CB.

[0033] When the processing circuit 34 further receives a release command for the circuit breaker CB from the central processing unit 20 via the communication circuit 35, it commands the digital output circuit 36 to output a trip signal to the circuit breaker CB. The digital output circuit 36 outputs a trip signal to the corresponding circuit breaker CB according to the command from the processing circuit 34.

[0034] (2. Hardware configuration example of the central processing unit) Referring to FIG. 2, the central processing unit 20 includes communication circuits 21 and 22, a processing circuit 23, and a storage device 24.

[0035] The communication circuit 21 transmits and receives data to and from the communication circuit 35 of the terminal device 30 via the communication line 40. The communication circuit 22 receives information on the state of the power system 2 as online data from the central power supply command station 10.

[0036] In the case of this embodiment, the processing circuit 23 is configured as a microcomputer including at least one CPU, at least one RAM, and at least one non-volatile memory. In this case, the CPU executes processing according to a control program and a simulation program stored in the non-volatile memory and / or the storage device 24. The control program and the simulation program may be provided as a non-transitory storage medium or may be provided via a network.

[0037] Note that the processing circuit 23 may be configured as at least one FPGA or may be configured as at least one ASIC. Alternatively, the processing circuit 34 may be configured by any combination of a CPU, an FGPA, and an ASIC.

[0038] The memory device 24 is, for example, a hard disk, an SSD (Solid State Drive), or other non-temporary non-volatile memory device.

[0039] [Functional Configuration of Central Processing Unit] Figure 3 is a block diagram showing the functional configuration of the central processing unit 20 in FIGS. 1 and 2. In FIG. 3, the central power supply command station 10 and each terminal device 30 related to the operation of the central processing unit 20 are also shown. As shown in FIG. 3, the processing circuit 23 of the central processing unit 20 functions as a pre-calculation unit 50 and a post-control unit 60.

[0040] The pre-calculation unit 50 receives online data 61 representing the state of the power grid topology (such as the open / closed state of switches), the power generation amount of each generator, and the demand of each load from the central power supply command station 10. The pre-calculation unit 50 performs transient stability calculations for each assumed accident (accident point and accident type) preset using the online data 61. The pre-calculation unit 50 determines a plurality of generators (renewable energy power generation devices and synchronous generators) to be power-controlled for each assumed accident based on the results of the transient stability calculations. The pre-calculation unit 50 stores a control table 63 associating the determined power-controlled generators with the assumed accidents in the memory device 24.

[0041] The stability analysis program 62 used in the above transient stability calculation simulates the time evolution of various phenomena occurring in the power system in the time domain from about 0.1 second to about several tens of seconds. As the stability analysis program 62, for example, the transient stability analysis (Y method) of the "Power System Integrated Analysis Tool CPAT" developed by the Electric Power Central Research Institute is used.

[0042] When an accident actually occurs, the post-control unit 60 determines the generators to be controlled (renewable energy power generation devices and synchronous generators) by comparing the information on the accident point and accident type received from each terminal device 30 with the control table. The post-control unit 60 transmits a cutoff command to cut off the power generation devices to be controlled from the power grid 2 by outputting a trip signal for the corresponding circuit breaker CB to the terminal device 30 corresponding to the determined power generation devices to be controlled.

[0043] [Detailed operation of the pre-calculation unit] More specifically, the pre-calculation unit 50 includes a stability calculation unit 51, a power control candidate selection unit 52, and a power control target determination unit 53.

[0044] The stability calculation unit 51 performs transient stability calculations using the stability analysis program 62 for each assumed accident point and accident type, and determines the presence or absence of synchronous generators whose relative phase angle (hereinafter referred to as the phase angle) with respect to the phase angle (0°) of the reference synchronous generator exceeds the out-of-step judgment phase angle. The out-of-step judgment phase angle is set to, for example, 150° or 180°. To perform the out-of-step judgment of synchronous generators, it is necessary to perform calculations in the time domain for about several seconds. Hereinafter, such calculations are referred to as detailed stability calculations.

[0045] Based on the results of the detailed stability calculations, the power control candidate selection unit 52 selects candidate synchronous generators and renewable energy power generation devices to be the power control targets.

[0046] Specifically, in the case of the system stabilization system 1 of Embodiment 1, the power control candidate selection unit 52 sets the time point when the phase angle of any synchronous generator exceeds the out-of-step judgment phase angle as the out-of-step judgment time, and calculates the center of inertia δ M at the out-of-step judgment time according to the following formula (1). Then, the power control candidate selection unit 52 sets the generator with an accelerating tendency whose phase angle at the out-of-step judgment time exceeds the center of inertia δ M as the synchronous generator to be the power control target. A method for further narrowing down the candidate synchronous generators to be the power control targets will be described in Embodiment 2.

[0047]

Equation

[0048] The above formula (1) represents the weighted average of the phase angles δi with the inertia constants Mi of the respective synchronous generators constituting the power system 2 as weights. For simplicity, assuming the inertia constants of two synchronous generators SG1 and SG2 are M1 and M2 respectively, and the respective phase angles are δ1 and δ2, the weighted average is expressed as (M1×δ1 + M2×δ2) / (M1 + M2).

[0049] Also, in the case of the system stabilization system 1 of Embodiment 1, the power control candidate selection unit 52 selects a renewable energy power generation device installed in a specific range according to the accident point as a power control target candidate. For example, a renewable energy power generation device installed on the side of the accelerating tendency generator from the accident point is selected as a power control target candidate. A method for further appropriately narrowing down the renewable energy power generation devices that are power control target candidates will be described in Embodiment 3.

[0050] The power control target determination unit 53 determines a generator to be power controlled in order to stabilize the power system 2 from among the generators (synchronous generators and renewable energy power generation devices) that are power control target candidates selected by the power control candidate selection unit 52. At this time, the power control target determination unit 53 determines the priority order of the generators to be power controlled based on the evaluation indices of the following formulas (2) and (3).

[0051]

Equation

[0052] The evaluation index of formula (2) is used to determine the priority order of the power control targets of synchronous generators. Specifically, when the i-th synchronous generator among the synchronous generators that are power control target candidates is power controlled in a non-accident state, the change ΔPE ij in the output power of the synchronous generator j of each power control target candidate except the i-th one is calculated (usually, the output power increases). Then, the sum of these changes ΔPE ij is used as the evaluation index of the i-th synchronous generator.

[0053] (3) The evaluation index is used to determine the power control target of the renewable energy power generation device. Specifically, when the i-th renewable energy power generation device among the renewable energy power generation devices of the power control target candidates is power-controlled in a non-accident state, the change ΔPE in the output power of the synchronous generator j of each power control target candidate ij is calculated. Then, the value obtained by dividing the sum of these output power changes ΔPE ij by the power control amount (i.e., the interrupted power) of the i-th renewable energy power generation device is used as the evaluation index of the i-th renewable energy power generation device.

[0054] (2) The evaluation index focuses on the change in the output power of the synchronous generator, while the evaluation index of (3) focuses on the change in the output power of the synchronous generator per unit power control amount by dividing the evaluation index of (2) by the power control amount of the generator of the power control target. As a result, generators with purely high power control effects can be prioritized. In the present disclosure, the evaluation index of (3) is also referred to as the normalized evaluation index.

[0055] For the calculation of the output power in the above equations (2) and (3), the same stability analysis program 62 as in the case of detailed stability calculation is used. However, since it is only necessary to calculate the output power of the synchronous generator of each power control target candidate, a calculation in a time domain of about 0.1 seconds is sufficient.

[0056] Hereinafter, the procedure for selecting the generator of the power control target using the above evaluation indexes (2) and (3) will be described. FIGS. 4 and 5 are flowcharts showing the procedure for selecting the generator of the power control target for each assumed accident. In FIGS. 4 and 5, the synchronous generator is abbreviated as SG (Synchronous Generator), and the renewable energy power generation device is abbreviated as RES (Renewable Energy Source).

[0057] Among the generators to be subjected to power control, renewable energy power generation devices are given priority over synchronous generators. The flowchart of FIG. 4 shows the procedure for selecting the renewable energy power generation device to be subjected to power control, and the flowchart of FIG. 5 shows the procedure for selecting the synchronous generator to be subjected to power control when the power system 2 cannot be stabilized by only the renewable energy power generation device. The processes of FIGS. 4 and 5 are executed for each assumed accident.

[0058] Referring to FIG. 4, in the first step S10, the stability calculation unit 51 performs a detailed stability calculation in a state without power control for the assumed accident (that is, assuming a certain accident point and accident type), and determines whether the power system 2 is stable (step S20).

[0059] As a result, when the power system 2 is stable (that is, when there is no synchronous generator having a phase angle exceeding the out-of-step judgment phase angle), the power control target determination unit 53 registers it in the control table 63 as no power control for the assumed accident (step S30).

[0060] On the other hand, when the power system 2 becomes unstable (that is, when the phase angle of any synchronous generator exceeds the out-of-step judgment phase angle), the process proceeds to steps S40 and S50. Steps S40 and S50 may be executed in either order or in parallel.

[0061] In step S40, the power control candidate selection unit 52 selects a synchronous generator as a candidate for the power control target. In the case of Embodiment 1, the accelerating tendency generator having a phase angle larger than the center of inertia δM represented by Equation (1) is selected as the synchronous generator of the power control target candidate.

[0062] In step S50, the power control candidate selection unit 52 selects a renewable energy power generation device as a candidate for the power control target. In the case of Embodiment 1, the renewable energy power generation device connected to the transmission line on the accelerating tendency generator side from the accident point is selected as the renewable energy power generation device of the power control target candidate.

[0063] In the following steps S70 to S110, the renewable energy power generation devices to be subjected to power control are selected in the stacking manner from the highest to the lowest in terms of the normalization evaluation index of the above formula (3). Since the reasonable procedure of disconnecting from the power grid 2 in order from the renewable energy power generation device with a high normalization evaluation index, that is, a high power control efficiency, it is easy to fulfill the explanatory responsibility.

[0064] Specifically, the stability calculation unit 51 first calculates the detailed stability when the renewable energy power generation device with the highest normalization evaluation index is subjected to power control. As a result, if the power grid 2 becomes unstable (NO in step S80) and there are other renewable energy power generation devices as power control target candidates (YES in step S100), the power control target determination unit 53 further adds the renewable energy power generation device with the highest normalization evaluation index among the unselected power control target candidate renewable energy power generation devices to the power control target. The stability calculation unit 51 performs the detailed stability calculation in this case (step S110).

[0065] As a result of repeating the above, when the execution result of the detailed stability calculation becomes stable (YES in step S80), the power control target determination unit 53 registers the already selected renewable energy power generation device in the control table 63 as the power control target for coping with the assumed accident. On the other hand, when the execution result of the detailed stability calculation is still unstable even when all the renewable energy power generation devices as power control target candidates are subjected to power control (NO in step S100), the process proceeds to step S120 in FIG. 5.

[0066] In steps S120 to S180 in FIG. 5, the synchronous generators to be subjected to power control necessary for stabilizing the power grid 2 are selected so that the total power control amount is minimized and the number of synchronous generators to be subjected to power control is minimized. However, since it takes too much calculation time to perform the detailed stability calculation for all combinations of the synchronous generators as power control target candidates, the selected synchronous generators as power control targets are sub-optimal by the following procedure. Specifically, while preferentially selecting the power control target candidates with a large evaluation index in formula (2), the synchronous generators as power control target candidates that minimize the total power control amount are selected.

[0067] More specifically, in addition to all the renewable energy power generation devices to be power-controlled, the power control target determination unit 53 selects, as the power control target, the synchronous generator having the highest evaluation index in formula (2). The stability calculation unit 51 performs detailed stability calculation in this case (step S120). As a result, if the power grid 2 is unstable (NO in step S130) and there is another synchronous generator as a power control target candidate (YES in step S160), the power control target determination unit 53 further adds, as the power control target, the synchronous generator having the highest evaluation index in formula (2) from among the unselected synchronous generators as power control target candidates. The stability calculation unit 51 performs detailed stability calculation in this case (step S170).

[0068] As a result of repeating the above, when the execution result of the detailed stability calculation becomes stable (YES in step S130), the power control target determination unit 53 registers the combination of the already selected synchronous generators in the control pattern list (step S140). Then, after excluding the synchronous generator selected immediately before (step S150), the power control target determination unit 53 adds, as the power control target, the synchronous generator having the highest evaluation index in formula (2) from among the other unselected power control target candidates. The stability calculation unit 51 performs detailed stability calculation in this case (step S170). Then, the process returns to step S130, and the above procedure is repeated.

[0069] Finally, when there is no synchronous generator as a power control target candidate (NO in step S160), the process proceeds to step S180. In step S180, the power control target determination unit 53 determines, as the power control target, the combination of synchronous generators having the smallest total power control amount from among the plurality of combinations of synchronous generators registered in the control pattern list. The power control target determination unit 53 registers the combination of the renewable energy power generation device and the synchronous generator determined as the power control target in association with the assumed accident in the control table 63. Thus, the selection of the generator as the power control target corresponding to the assumed accident is completed.

[0070] [Effects of Embodiment 1] As described above, according to the system stability system 1 of Embodiment 1, after preferentially selecting the renewable energy power generation device as the object of power control, the combination of synchronous generators with the minimum total power control amount can be selected as the object of power line based on the evaluation index of the above formula (2). In addition, the renewable energy power generation device as the object of power control can be selected according to a reasonable procedure based on the normalized evaluation index of the above formula (3).

[0071] Embodiment 2. In Embodiment 2, a modification example of the method for selecting the synchronous generator as the candidate for power control in step S40 of FIG. 4 will be described. Specifically, the power control candidate selection unit 52 of the pre-calculation unit 50 selects a synchronous generator whose determination index on the left side of the following formula (4) exceeds the threshold value as a candidate for the object of power control.

[0072]

Equation

[0073] In the above formula (4), δ sj / δ set on the left side is the phase angle δ sj normalized by the out-of-step judgment phase angle δ set , and is an index for selecting a synchronous generator with a large phase angle at the time of out-of-step judgment. In the case of a synchronous generator having an out-of-step judgment phase angle, this index becomes 1, and in the case of a synchronous generator having a phase angle close to the out-of-step judgment phase angle, this index is smaller than 1 but close to 1.

[0074] On the other hand, in the above (4), Δδ sj / Δδ sjMAX on the left side is an index for selecting a synchronous generator having a phase with a large deviation from the initial phase at the start of simulation. The phase angle deviation Δδ sj is normalized by the maximum value Δδ sjMAX of the phase angle deviation. Therefore, in the case of the synchronous generator with the largest phase angle deviation, this index becomes 1, and in the case of a synchronous generator with a relatively large phase angle deviation, this index is smaller than 1 but close to 1.

[0075] By using the determination formula in (4) above, a synchronous generator with a high effect for system stabilization can be selected as a candidate for power control target, and the candidates for power control target can be narrowed down compared to the case of Embodiment 1. In (4), the value obtained by multiplying the normalized phase angle and the normalized phase angle deviation is used as a determination index, but there is no problem even if either one of these is used as the determination index.

[0076] Embodiment 3. In Embodiment 3, a modified example of the method for selecting a renewable energy power generation device as a power control target candidate in step S50 of FIG. 4 will be described.

[0077] Specifically, first, the power control candidate selection unit 52 of the pre-calculation unit 50 calculates the normalized evaluation index of formula (3) for the synchronous generators that are candidates for power control target. That is, when the i-th synchronous generator among the synchronous generators that are candidates for power control target is controlled in a non-accident state, the change ΔPE in the output power of the synchronous generator j of each power control target candidate excluding the i-th one ij is calculated. Then, the value obtained by dividing the sum of these changes ΔPE in output power ij by the power control amount of the i-th synchronous generator (that is, the interrupted power) is the normalized evaluation index of the i-th synchronous generator.

[0078] Next, the power control candidate selection unit 52 sets the minimum value among the normalized evaluation indexes of the respective synchronous generators that are candidates for power control target as a threshold value. Then, the power control candidate selection unit 52 determines a renewable energy power generation device whose normalized evaluation index is greater than this threshold value as a candidate for power control target. Thereby, a renewable energy power generation device with a high effect for system stabilization can be selected as a candidate for power control target, and the candidates for power control target can be narrowed down compared to the case of Embodiment 1.

[0079] It should be considered that all the embodiments disclosed this time are illustrative in all respects and not restrictive. The scope of this application is indicated by the claims rather than the above description, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Description of Reference Numerals

[0080] 1 System stabilization system, 2 Power system, 10 Central power supply command post, 20 Central processing unit, 21, 22, 35 Communication circuit, 23, 34 Processing circuit, 24 Memory device, 30 Terminal device, 31 Auxiliary transformer, 32 Analog filter, 33 A / D converter, 36 Digital output circuit, 37 Digital input circuit, 40, 42 Communication line, 50 Pre-calculation unit, 51 Stability calculation unit, 52 Electric control candidate selection unit, 53 Electric control target determination unit, 60 Post-control unit, 61 Online data, 62 Stability analysis program, 63 Control table, BL Bus, CB Circuit breaker, CT Current transformer, PC Power converter, PL Transmission line, PV Photovoltaic power generation device, SG Synchronous generator, TR Transformer, VT Voltage transformer, WT Wind power generation device.

Claims

1. A plurality of terminal devices, each associated with one of a plurality of generators including a synchronous generator and a renewable energy power generation device, and shutting off the corresponding generator from the power grid according to a shut-off command; An after-control unit that, when an accident occurs in the power grid, transmits the shut-off command to the terminal device corresponding to the generator to be controlled according to a control table; A pre-calculation unit that creates in advance the control table in which the generators to be controlled are associated with the assumed accidents by performing stability calculations for each assumed accident, The pre-calculation unit includes: A control candidate selection unit that selects a plurality of synchronous generators and a plurality of renewable energy power generation devices that are candidates for control based on the results of the stability calculation; A control target determination unit that determines a renewable energy power generation device to be controlled from among the control target candidates in the order of priority based on a first evaluation index, and when the stability calculation result does not become stable even if all the renewable energy power generation devices of the control target candidates are controlled, determines a synchronous generator to be controlled from among the control target candidates so that the total control amount becomes as small as possible based on the order of priority based on a second evaluation index, The first evaluation index for the p-th renewable energy power generation device among the renewable energy power generation devices of the control target candidates is a value obtained by dividing the sum of the output change amounts of the respective synchronous generators of the control target candidates when the p-th renewable energy power generation device is controlled by the control amount of the p-th renewable energy power generation device, The second evaluation index for the q-th synchronous generator among the synchronous generators of the control target candidates is the sum of the output change amounts of the respective synchronous generators of the control target candidates excluding the q-th one when the q-th synchronous generator is controlled. A system for stabilizing the power grid.

2. The control candidate selection unit uses the result of the stability calculation to obtain the phase angle of each synchronous generator provided in the power grid at the time of out-of-step determination when the phase angle of any synchronous generator provided in the power grid reaches the out-of-step determination phase angle, and calculates a weighted average obtained by weighting the phase angles of the respective synchronous generators with the inertia constants of the respective synchronous generators as the center of inertia, The system for stabilizing the power grid according to claim 1, wherein the control candidate selection unit selects, as control target candidates, synchronous generators having a phase angle larger than the center of inertia at the time of out-of-step determination.

3. The power control candidate selection unit uses the result of the stability calculation to obtain, at the out-of-step determination time when the phase angle of any synchronous generator provided in the power system reaches the out-of-step determination phase angle, the phase angle of each synchronous generator provided in the power system and the phase angle deviation from the initial phase angle. The power control candidate selection unit selects, as a power control target candidate, a synchronous generator in which a third evaluation index calculated based on the phase angle and the phase angle deviation exceeds a threshold value. For the r-th synchronous generator among the synchronous generators provided in the power system, the third evaluation index is the product of the value obtained by dividing the phase angle of the r-th synchronous generator at the out-of-step determination time by the out-of-step determination phase angle and the value obtained by dividing the phase angle deviation of the r-th synchronous generator at the out-of-step determination time by the maximum value of the phase angle deviations of each synchronous generator provided in the power system. The system stabilization system according to claim 1.

4. The power control candidate selection unit uses the result of the stability calculation to obtain, at the out-of-step determination time when the phase angle of any synchronous generator provided in the power system reaches the out-of-step determination phase angle, the phase angle of each synchronous generator provided in the power system. The power control candidate selection unit selects, as a power control target candidate, a synchronous generator in which a third evaluation index calculated based on the phase angle exceeds a threshold value. For the r-th synchronous generator among the synchronous generators provided in the power system, the third evaluation index is the value obtained by dividing the phase angle of the r-th synchronous generator at the out-of-step determination time by the out-of-step determination phase angle. The system stabilization system according to claim 1.

5. The power control candidate selection unit uses the result of the stability calculation to obtain, at the out-of-step determination time when the phase angle of any synchronous generator provided in the power system reaches the out-of-step determination phase angle, the phase angle deviation from the initial phase angle of each synchronous generator provided in the power system. The power control candidate selection unit selects, as a power control target candidate, a synchronous generator in which a third evaluation index calculated based on the phase angle deviation exceeds a threshold value. For the r-th synchronous generator among the synchronous generators provided in the power system, the third evaluation index is the value obtained by dividing the phase angle deviation of the r-th synchronous generator at the out-of-step determination time by the maximum value of the phase angle deviations of each synchronous generator provided in the power system. The system stabilization system according to claim 1.

6. The power control candidate selection unit calculates the first evaluation index for each of the synchronous generators of the power control target candidates, determines the minimum value of the first evaluation index among the synchronous generators of the power control target candidates, The first evaluation index for the s-th synchronous generator among the synchronous generators of the power control target candidates is the sum of the output change amounts of each of the synchronous generators of the power control target candidates excluding the s-th when the s-th synchronous generator is power-controlled, divided by the power control amount of the s-th synchronous generator. The power control candidate selection unit calculates the first evaluation index for each of the renewable energy power generation devices provided in the power grid, and selects a renewable energy power generation device having the first evaluation index greater than the minimum value as the power control target candidate. The system stability system according to any one of claims 2 to 5.

7. When an accident occurs in a power grid provided with a plurality of generators including a synchronous generator and a renewable energy power generation device, the processing circuit transmits a cutoff command to a terminal device corresponding to the power control target generator according to a control table; The processing circuit includes a step of preliminarily creating the control table in which the power control target generator is associated with the assumed accident by performing a stability calculation for each assumed accident. The step of preliminarily creating the control table is selecting a plurality of synchronous generators to be power control target candidates based on the result of the stability calculation; selecting a plurality of renewable energy power generation devices to be power control target candidates based on the result of the stability calculation; determining a renewable energy power generation device to be a power control target from among the power control target candidates in the order of priority based on the first evaluation index; when the stability calculation result does not become stable even if all the renewable energy power generation devices of the power control target candidates are power-controlled, determining a synchronous generator to be a power control target from among the power control target candidates so that the total power control amount becomes as small as possible based on the order of priority based on the second evaluation index; registering the generator determined as the power control target in the control table in association with the assumed accident. The first evaluation index for the p-th renewable energy power generation device among the renewable energy power generation devices of the power control target candidates is the value obtained by dividing the sum of the output change amounts of the respective synchronous generators of the power control target candidates when the p-th renewable energy power generation device is power-controlled by the power control amount of the p-th renewable energy power generation device. The second evaluation index for the q-th synchronous generator among the synchronous generators of the power control target candidates is the sum of the output change amounts of the respective synchronous generators of the power control target candidates excluding the q-th one when the q-th synchronous generator is power-controlled. This is a system stabilization method.

8. The step of selecting a plurality of synchronous generators as power control target candidates includes: Using the result of the stability calculation, at the demodulation determination time when the phase angle of any synchronous generator provided in the power system reaches the demodulation determination phase angle, obtaining the phase angles of the respective synchronous generators provided in the power system; Calculating, as the center of inertia, the weighted average obtained by weighting the obtained phase angles of the respective synchronous generators with the inertia constants of the respective synchronous generators; The method for stabilizing a system according to claim 7, further including the step of selecting, as power control target candidates, the synchronous generators whose phase angles are larger than the center of inertia at the demodulation determination time.

9. The step of selecting a plurality of synchronous generators as power control target candidates includes: Using the result of the stability calculation, at the demodulation determination time when the phase angle of any synchronous generator provided in the power system reaches the demodulation determination phase angle, obtaining the phase angles of the respective synchronous generators provided in the power system and the phase angle deviations from the initial phase angles; The method for stabilizing a system according to claim 7, further including the step of selecting, as power control target candidates, the synchronous generators for which a third evaluation index calculated based on the obtained phase angles and phase angle deviations exceeds a threshold value. The third evaluation index for the r-th synchronous generator among the synchronous generators provided in the power system is the product of the value obtained by dividing the phase angle of the r-th synchronous generator at the demodulation determination time by the demodulation determination phase angle and the value obtained by dividing the phase angle deviation of the r-th synchronous generator at the demodulation determination time by the maximum value of the respective phase angle deviations of the synchronous generators provided in the power system.

10. The step of selecting a plurality of synchronous generators as power control target candidates includes: Using the result of the stability calculation, at the time of out-of-step determination when the phase angle of any synchronous generator provided in the power system reaches the out-of-step determination phase angle, obtaining the phase angle of each synchronous generator provided in the power system; selecting, as a power control target candidate, a synchronous generator in which a third evaluation index calculated based on the obtained phase angle exceeds a threshold value; The third evaluation index for the r-th synchronous generator among the synchronous generators provided in the power system is a value obtained by dividing the phase angle of the r-th synchronous generator at the time of out-of-step determination by the out-of-step determination phase angle. The system stabilization method according to claim 7.

11. The step of selecting a plurality of synchronous generators as power control target candidates includes: Using the result of the stability calculation, at the time of out-of-step determination when the phase angle of any synchronous generator provided in the power system reaches the out-of-step determination phase angle, obtaining the phase angle deviation from the initial phase angle of each synchronous generator provided in the power system; selecting, as a power control target candidate, a synchronous generator in which a third evaluation index calculated based on the obtained phase angle deviation exceeds a threshold value; The third evaluation index for the r-th synchronous generator among the synchronous generators provided in the power system is a value obtained by dividing the phase angle deviation of the r-th synchronous generator at the time of out-of-step determination by the maximum value of the phase angle deviations of each of the synchronous generators provided in the power system. The system stabilization method according to claim 7.

12. The step of selecting a plurality of renewable energy power generation devices as power control target candidates includes: calculating the first evaluation index for each of the synchronous generators of the power control target candidates and determining the minimum value of the first evaluation index among the synchronous generators of the power control target candidates; The first evaluation index for the s-th synchronous generator among the synchronous generators of the power control target candidates is a value obtained by dividing the sum of the output change amounts of the respective synchronous generators of the power control target candidates excluding the s-th synchronous generator when the s-th synchronous generator is power-controlled by the power control amount of the s-th synchronous generator; The step of selecting a plurality of renewable energy power generation devices as power control target candidates includes: For each of the renewable energy power generation devices provided in the power system, calculating the first evaluation index, and further including a step of selecting, as the power control target candidate, a renewable energy power generation device having the first evaluation index greater than the minimum value, the system stabilization method according to any one of claims 8 to 11.

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