Power system frequency stabilization device, power system frequency stabilization method, and power system frequency stabilization program

Abstract

To provide a power system frequency stabilization device that controls, when a system fault occurs, an inverter device to prevent an increase in local frequency fluctuations that may occur due to differences in the distribution of inertia within a power system.SOLUTION: A power system frequency stabilization device 10 comprises an inverter device that has a high speed frequency response capability capable of connecting an electric output to a power system 20 and adjusting the electric output within 10 seconds, preferably within 2 seconds, when the frequency of the power system 20 fluctuates, a pre-correction area frequency index calculation unit 13 that calculates an evaluation index of frequency fluctuation for each partial system area set in the power system 20, a control content determination unit 16 that determines a control amount of the inverter device using an installation node of the inverter device, data on frequency response, data on a required amount of the high speed frequency response in the power system 20, and a calculation result of an evaluation index of frequency fluctuation for each partial system area, and a post-correction area frequency stability determination unit 17 that determines whether the evaluation index of the frequency fluctuation for each partial system area falls within a specified range.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power system frequency stabilization device, a frequency stabilization method, and a frequency stabilization program. [Background technology]

[0002] The frequency of the power system is maintained by controlling power generation and demand so that they match each other from moment to moment. For example, if the balance between power generation and demand (supply and demand balance) can no longer be maintained due to the shutdown of generators or demand, the frequency will fluctuate, and if the amount of fluctuation exceeds a certain level, the generator or load will be disconnected from the system, and in the worst case, a major blackout may occur. In this case, the greater the inertial energy (inertia) of the rotary generator, the slower the frequency change will be, and the more time there is for operations to maintain the supply and demand balance, making it possible to reduce the amount of load (demand) that needs to be cut off. In addition, the synchronizing power of rotary generators allows multiple generators to correct each other to the same rotation speed, making it possible to suppress frequency fluctuations in the power system.

[0003] On the other hand, many of the renewable energy sources, such as solar power generation and wind power generation, which have been increasingly introduced in recent years, are connected to the power grid via inverters that convert direct current (DC) power to alternating current (AC). Therefore, they do not have the inertia or synchronizing power that rotary generators possess. Furthermore, with the abolition of rotary generators, the inertia force of rotary generators is supplied only to certain regions. This results in a biased distribution of inertia within the power grid. In such a system with a biased distribution of inertia, if a generator falls off due to a system accident caused by a disaster or lightning strike during a time period when inertia is low, the frequency fluctuation in the low-inertia region will be greater than the frequency fluctuation in other regions, raising concerns about the risk of a major blackout.

[0004] In response to this, measures have been considered to quickly control active power in a direction to eliminate the supply-demand imbalance, using inverter-type generators (inverter-type power sources), power storage facilities, self-commutated var compensators with power storage facilities, and DC power transmission systems. Hereinafter, in this specification, the adjustment capability supplied within 10 seconds, preferably within 2 seconds, after the occurrence of a grid fault is referred to as "fast frequency response." The classification of fast frequency response may include a response by pseudo-inertia control, which causes an inverter-type power source to move with the same inertia as a rotary generator.

[0005] For example, Patent Document 1 discloses a frequency control method that accurately grasps the simulated inertial force of inverter-type power sources included in a local grid or each area within the grid, and responds to changes in the simulated inertial force during a grid accident. In addition, in a grid-connected inverter that suppresses fluctuations in grid frequency by virtual synchronous generator control, a method is also known in which the frequency convergence speed is shortened by adjusting the pseudo inertia coefficient to a smaller value after the grid frequency reaches the maximum frequency fluctuation point. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2023-063791 A Summary of the Invention [Problem to be solved by the invention]

[0007] In the method described in the above-mentioned Patent Document 1, the amount of change in simulated inertia caused by inverter-type power sources in each area during a system accident is taken into consideration, and the amount of power shedding and load shedding is calculated to control the frequency. However, the frequency change rate or maximum frequency deviation of the entire power system is used as an evaluation index for frequency fluctuation, and differences in frequency fluctuation between areas that may occur in a system with uneven distribution of inertia are not taken into consideration. For example, assume that there are areas A and B in the same power system, and a rotary generator is operating only in area A. If a system accident causes the rotary generator in area A to trip, there is a risk that the fluctuation in frequency in area B, which has low inertia, will be greater than the fluctuation in the average frequency of the entire power system. In this case, the evaluation method in Patent Document 1 cannot adequately grasp the stability of frequency in all areas in the power system, and cannot prevent disconnection of generators and loads due to frequency fluctuations that may occur locally in area B.

[0008] On the other hand, it is also possible to shorten the frequency convergence speed by adjusting the pseudo inertia coefficient to a smaller value after the system frequency reaches the maximum frequency fluctuation point. In this method, control is performed using the frequency measured at the busbar to which the inverter-type power source is connected. For this reason, the distribution of inertia within the power system and the location of the inverter-type power source are not taken into consideration, and local frequency fluctuations that may occur in areas with low inertia cannot be suppressed.

[0009] Therefore, an object of the present invention is to suppress an increase in local frequency fluctuation that may occur due to differences in the distribution of inertia within a power system in the event of a system accident in a power system to which a large number of inverter-type generators, power storage equipment, self-commutated var compensators with power storage equipment, and DC transmission systems are connected. [Means for solving the problem]

[0010] In order to solve the above-mentioned problems, the frequency stabilization device for a power system of the present invention is characterized in that it comprises an inverter device that connects an electric output to a power system and has a high-speed frequency response capability capable of adjusting the electric output within 10 seconds, preferably within 2 seconds, when the frequency of the power system fluctuates; a pre-correction area frequency index calculation unit that calculates an evaluation index of frequency fluctuation for each partial system area set in the power system based on the position of the inverter device; a control content determination unit that determines a control amount of the inverter device using the installation node of the inverter device, data related to the frequency response, data related to the required amount of high-speed frequency response in the power system, and the calculation result of the evaluation index of frequency fluctuation for each partial system area; and a post-correction area frequency stability determination unit that determines whether the evaluation index of frequency fluctuation for each partial system area falls within a specified range.

[0011] The method for stabilizing the frequency of a power system of the present invention is characterized by comprising the steps of: a pre-correction area frequency index calculation unit calculating an evaluation index of frequency fluctuations for each partial system area set in the power system based on data related to inertia within the power system, using as a reference the position of an inverter device with a high-speed frequency response that can adjust an electrical output within 10 seconds, preferably within 2 seconds; a control content determination unit connecting the electrical output to the power system, and determining, during frequency fluctuations in the power system, a control amount for the inverter device using an installation node of the inverter device, data related to the frequency response, data related to a required amount of high-speed frequency response in the power system, and a calculation result of the evaluation index of frequency fluctuations for each partial system area; and a post-correction area frequency stability determination unit determining whether the evaluation index of frequency fluctuations for each partial system area falls within a specified range.

[0012] The power system frequency stabilization program of the present invention causes a computer to execute the following steps: calculating an evaluation index of frequency fluctuations for each partial system area set in the power system based on data regarding inertia within the power system, using the position of an inverter device with a high-speed frequency response that can adjust an electrical output within 10 seconds, preferably within 2 seconds, as a reference; connecting an electrical output to the power system, and when the frequency of the power system fluctuates, determining a control amount for the inverter device using the installation node of the inverter device, data regarding the frequency response, data regarding the required amount of high-speed frequency response in the power system, and the calculation result of the evaluation index of frequency fluctuations for each partial system area; and determining whether the evaluation index of frequency fluctuations for each partial system area falls within a specified range. Other means will be described in the description of the embodiment of the invention. Effect of the Invention

[0013] According to the present invention, in a power system to which a large number of inverter-type generators, power storage equipment, self-commutated var compensators with power storage equipment, and DC transmission systems are connected, in the event of a system fault, it is possible to suppress an increase in local frequency fluctuation that may occur due to differences in the distribution of inertia within the power system. [Brief description of the drawings]

[0014] [Figure 1] 1 is a block diagram showing a hardware configuration of a frequency stabilization device connected to a power grid according to a first embodiment. FIG. [Diagram 2] FIG. 2 is a diagram showing a processing functional configuration of a frequency stabilization device for a power system. [Diagram 3] FIG. 13 is a diagram illustrating an example of a configuration of a frequency response control value database. [Figure 4] 13 is a flowchart showing the process of an inertia center distance calculation unit. [Diagram 5] 11A and 11B are diagrams illustrating an example of calculation results of an area frequency index and a center of inertia frequency. [Figure 6]FIG. 13 is a diagram showing an example of the configuration of a center of inertia distance ranking database for an arbitrary contingency fault. [Figure 7] 13 is a flowchart showing a process of a control content determination unit for fast frequency response; [Figure 8] FIG. 13 is a diagram showing an example of the configuration of a fast frequency response control content database for an arbitrary contingency fault. [Figure 9] FIG. 11 is a diagram showing a processing functional configuration of a power system frequency stabilization device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiment of the present invention will be described in detail with reference to the drawings. Note that the embodiment described below does not limit the invention described in the claims, and all of the elements and combinations thereof described in the embodiment are not necessarily essential to the solution of the invention.

[0016] In describing this embodiment, when there are multiple devices or components with the same configuration, they will be described using the same numbers, and when describing each individual device or component with the same configuration, they will be distinguished by adding an alphabetical suffix to the common number.

[0017] First Embodiment FIG. 1 is a block diagram showing a hardware configuration of a frequency stabilization device 10 connected to a power system 20 according to a first embodiment.

[0018] The frequency stabilization device 10 of the power system 20 is configured, for example, by a computer system. The frequency stabilization device 10 calculates the area frequency index, the center of inertia distance ranking, the fast frequency response control content, and the stabilization control content of the power system 20. At this time, the frequency stabilization device 10 can provide a control amount that takes into account the distribution of inertia of the power system 20 and the position of the renewable energy power source, and can stabilize the frequency and reduce the control amount when a supply-demand imbalance occurs due to a system failure.

[0019] The frequency stabilization device 10 includes a display unit 31, an input unit 32, a communication unit 33, a CPU 34, a memory 35, a storage unit 37, an input system data group 4, and an output system data group 5. The display unit 31, the input unit 32, the communication unit 33, the CPU 34, the memory 35, the storage unit 37, the input system data group 4, and the output system data group 5 are connected via a bus line 36.

[0020] The display unit 31 displays parameters handled by the frequency stabilizing device 10 and processing results in the frequency stabilizing device 10. The display unit 31 may be a display device, or a printer device or an audio output device may be used together with the display device.

[0021] The input unit 32 inputs various conditions for operating the frequency stabilization device 10. The input unit 32 can use a keyboard and a mouse, and may also include at least one of a touch panel or a voice instruction device.

[0022] The communication unit 33 includes a circuit and a communication protocol for connecting to the communication network 300. The communication network 300 may be a WAN (Wide Area Network) such as the Internet, or a LAN (Local Area Network) such as WiFi or Ethernet (registered trademark), or may be a mixture of a WAN and a LAN.

[0023] The CPU 34 executes a calculation program to specify image data to be displayed, and searches for data in various databases. The CPU 34 may be configured as one or more semiconductor chips, or as a computer device such as a calculation server. The CPU 34 may include a neural network.

[0024] The memory 35 is configured as, for example, a RAM (Random Access Memory), and stores computer programs, calculation result data required for each process, image data, etc. The data stored in the memory 35 is sent to the display unit 31 and displayed. The storage unit 37 is configured by, for example, a hard disk or a solid state drive (SSD), and stores a frequency stabilization program 38. The CPU 34 executes the frequency stabilization program 38 to realize each of the functional units described below.

[0025] The frequency stabilization device 10 is equipped with an input system data group 4 and an output system data group 5, which can be broadly divided. The input system data group 4 includes a system equipment database 41, an inverter characteristic database 42, a system measurement value database 44, a frequency response control value database 45, and a fault relay database 43. The output system data group 5 includes an area frequency index database 51, an inertia center distance ranking database 53, a high-speed frequency response control content database 52, and a stabilization control content database 54. In the figure, the database is abbreviated to "DB."

[0026] The system equipment database 41 stores data on equipment constituting the power system, such as line impedance (resistance, reactance, and capacitance to earth), system configuration, and generators (capacity, transient reactance, and the like).

[0027] The system measurement value database 44 stores information such as active power, reactive power, voltage, phase angle, current, power factor, tap value, and switch ON / OFF information between the power system and nodes, branches, transformers, static capacitors (SCs), shunt reactors (ShRs), etc. The system measurement value database 44 may store time stamped data and PMU (Phasor Measurement Unit) data. The system measurement value database 44 may store information obtained by measuring the system inertia of the power system 20 based on the measurement and storage information of each of the above-mentioned system points. The system measurement value database 44 may also store the operating status of inverter devices in the power system 20 based on the measurement and storage information of each of the above-mentioned system points.

[0028] The inverter characteristic database 42 stores data such as the installation node of the inverter device, frequency response characteristics (response speed and controllable amount of high-speed frequency response), etc. The inverter device may be any of an inverter-type generator, a power storage device, a self-commutated var compensator with a power storage device, and a DC transmission system, or may be other than these.

[0029] The fault relay database 43 stores the location and aspect patterns of faults as fault data transmitted by fault detection devices installed at various locations in the system. When a system accident occurs, the corresponding fault data is selected from the fault data transmitted by the fault detection devices and the previously stored data on the location and aspect of faults, and is transmitted to the high speed frequency response control content database 52 and the stabilization control content database 54.

[0030] The frequency response control value database 45 stores a required amount of high-speed frequency response required to keep the power system 20 stable when a supply-demand imbalance occurs due to a power source drop or load drop. The contents of the frequency response control value database 45 are assumed to be set in advance by a system operator.

[0031] Next, the output system data group 5 will be described. The area frequency index database 51 stores frequency indexes at the time of the occurrence of an assumed fault in the partial system area where each inverter device of the power system 20 is located. Hereinafter, in this specification, an area or partial system set based on the position of an inverter device capable of high-speed frequency response is referred to as a "partial system area" or simply an "area". Measurement information for appropriately and simply estimating the state of the partial system area is obtained from the system measurement value database 44.

[0032] The inertia center distance ranking database 53 stores the inertia center distance ranking of each partial system area calculated by this algorithm based on the inertia center frequency and area frequency index of the power system 20, as well as the corresponding control objects and controllable quantities. The fast frequency response control content database 52 stores the controlled object and the controlled amount when the inverter device executes the fast frequency control calculated by this algorithm.

[0033] The stabilization control content database 54 stores the amount of power control or negative control required to maintain the supply and demand balance when the frequency index in each partial system area cannot be kept within the specified range even when high-speed frequency control calculated by this algorithm is implemented on the inverter device in response to an assumed accident.

[0034] The frequency stabilization device 10 of the power system 20 can access measurement information of the power system 20 through a communication network 300. The power system 20 is a system interconnected via a plurality of synchronous generators 110A, 110B, loads 180A, 180B, nodes 160A to 160G, transformers 150A to 150E, and transmission lines 170A to 170G. The power system 20 is asynchronously interconnected with an external system 21 through a DC transmission system 190.

[0035] Here, the synchronous generators 110A, 110B are, for example, thermal power generators, hydroelectric power generators, or nuclear power generators. Various measuring instruments, circuit breakers, and fault detection devices for protecting, controlling, and monitoring the power system 20 are installed in the nodes 160A to 160G.

[0036] Battery 130A and renewable energy power source 120B are connected to node 160F. Renewable energy power source 120A is connected to node 160C. The renewable energy power supply 120C and the static var compensator 140A are connected to a node 160G. A DC transmission system 190 is connected to node 160C.

[0037] The storage battery 130A, the renewable energy power source 120B, the renewable energy power source 120C, the self-excited var compensator 140A, and the DC transmission system 190 are inverter devices that connect an electrical output to the power grid 20 and have a high-speed frequency response capability that enables the electrical output to be adjusted within at least 10 seconds, and preferably within 2 seconds, when the frequency of the power grid 20 fluctuates.

[0038] Node 160C is connected to node 160D via transmission line 170D. Node 160F is connected to node 160D via transformer 150D and transmission line 170E.

[0039] Node 160A is connected to node 160D via transmission line 170A. Node 160G is connected to node 160D via transformer 150E and transmission line 170F, and is connected to node 160E via transformer 150E and transmission line 170G. Node 160B is connected to node 160D via power transmission line 170B and to node 160E via power transmission line 170C.

[0040] The renewable energy power sources 120A to 120C are, for example, power sources such as solar power generation and wind power generation that are connected to the grid via an inverter, and those connected via a DC transmission system are also considered renewable energy power sources. In addition, the self-commutated var compensator 140A may be provided with a storage facility such as a storage battery or an electric double layer capacitor in order to provide a high-speed frequency response.

[0041] FIG. 2 is a diagram showing a processing functional configuration of the frequency stabilization device 10 of the power system 20. As shown in FIG. The frequency stabilization device 10 of the power system 20 includes the following functional units: a fault condition setting unit 11, a system simulation unit 12, a pre-correction area frequency index calculation unit 13, an inertia center distance calculation unit 14, a control priority determination unit 15, a control content determination unit 16, a post-correction area frequency stability determination unit 17, and a frequency stabilization calculation unit 18. The frequency stabilization device 10 further includes an input system data group 4 and an output system data group 5.

[0042] The accident condition setting unit 11 determines a hypothetical system accident (assumed accident) in the power system 20 of Fig. 1. The accident condition setting unit 11 sets the location, the aspect, the generator that trips, and the like as the conditions of the system accident. The conditions of the system accident set by the accident condition setting unit 11 may correspond to the contents of the fault relay database 43, may be set by input from the user, or the system accident may be appropriately set from a preset pattern.

[0043] The system simulation unit 12 creates a system analysis model of the power system 20 from the information of the input system data group 4, executes calculation programs such as a power flow calculation and a transient stability calculation, calculates the rotation speed of the generator or the phase of the node, and calculates the stability in the event of the occurrence of the accident set in the accident condition setting unit 11. At this time, the system simulation unit 12 executes the calculation program without considering the high-speed frequency response by the inverter device based on the inverter characteristics database 42. Furthermore, the calculation program executed by the system simulation unit 12 is not limited to the power flow calculation and transient stability calculation described above, and may be one for calculating a frequency fluctuation index of the entire system or a frequency fluctuation index of each partial system area.

[0044] The pre-correction area frequency index calculation unit 13 calculates an evaluation index of frequency fluctuation of the partial system area in which each inverter device is located from the generator rotation speed or node phase obtained by the system simulation unit 12, and stores the calculated index in the area frequency index database 51. The evaluation index of frequency fluctuation of each partial system area may be, for example, the node frequency or the node frequency change rate at the interconnection point of the inverter device, or, when there are multiple nodes as described above in the partial system area to be monitored, their average may be used.

[0045] The inertia center distance calculation unit 14 calculates the inertia center frequency using the generator rotation speed obtained in the system simulation unit 12 and information from the system equipment database 41, and calculates the distance Q between the inertia center and each partial system area from the area frequency index obtained from the pre-correction area frequency index calculation unit 13. i (i=1, 2, 3, ...) is calculated. This makes it possible to calculate the distance between the frequency of each partial system area and the center of inertia frequency of the entire power system, and makes it possible to determine control content that takes into account differences in the distribution of inertia within the power system and the resulting increases in local frequency fluctuations.

[0046] The control priority determination unit 15 determines the distance Q from the center of inertia calculated by the center of inertia distance calculation unit 14. i are sorted in descending order and stored in the inertia center distance ranking database 53 together with information on the inverter device of the corresponding partial system area i.

[0047] Based on the center of inertia distance ranking calculated by control ranking determination unit 15 and the required amount of fast frequency response obtained from frequency response control value database 45, control content determination unit 16 determines the inverter device that performs fast frequency response and its control amount, and stores it in fast frequency response control content database 52. Control content determination unit 16 determines the inverter device that performs fast frequency response and its control amount using the installation node of the inverter device, data related to frequency response, data related to the required amount of fast frequency response in the power system, and the calculation result of the evaluation index of frequency fluctuation for each partial system area. Control content determination unit 16 calculates the center of inertia frequency of power system 20, and uses this center of inertia frequency and the calculation result of pre-correction area frequency index calculation unit 13 to determine the control content of the inverter device.

[0048] The corrected area frequency stability determination unit 17 calculates an evaluation index of frequency fluctuations in each partial system area when the control contents stored in the fast frequency response control contents database 52 are executed, and determines whether the frequency fluctuation indexes in all partial system areas are within a specified range. Here, the evaluation index of frequency fluctuations in the partial system area is the frequency or rate of change of frequency (RoCoF: Rate of Change of Frequency) at the generator or bus in the power system.

[0049] When it is determined that the evaluation index of frequency fluctuation in any area is not within a specified range, the frequency stabilization calculation unit 18 calculates the amount of power shedding (power control amount) or the amount of load shedding (negative control amount) required to bring the evaluation index of frequency fluctuation in that area within the specified range. The amount of power shedding (power control amount) or the amount of load shedding (negative control amount) calculated by the frequency stabilization calculation unit 18 corresponds to the amount of control of the generator or the load for the power system 20. The frequency stabilization calculation unit 18 stores the calculation result in the stabilization control content database 54. The display unit 31 in FIG. 1 displays any of the information calculated by the pre-correction area frequency index calculation unit 13, the control content determination unit 16, the post-correction area frequency stability determination unit 17, and the frequency stabilization calculation unit .

[0050] FIG. 3 is a diagram showing an example of the configuration of the frequency response control value database 45. As shown in FIG. FIG. 3 shows the required amount of fast frequency response required when a supply-demand imbalance ΔP occurs due to a power source drop or load drop, with respect to the system inertia of the power system 20. The required amount of fast frequency response with respect to the system inertia is calculated in advance as the required amount for suppressing the index of frequency fluctuation of the power system within a threshold value for an assumed supply-demand imbalance accident, and is set by the system operator. For example, as shown in FIG. 3, when the system inertia is 20,000 [MWs] and a supply-demand imbalance accident of ΔP=600 [MW] occurs, the fast frequency response required for suppressing the index of frequency fluctuation within a certain range is considered to be 160 [MW]. The relationship between the system inertia and the fast frequency response may be calculated for all assumed supply-demand imbalance accidents, or may be calculated for a power source drop accident or load drop accident with the largest supply-demand imbalance. As shown in FIG. 3, the smaller the system inertia, the greater the required amount of fast frequency response. The greater the supply-demand imbalance ΔP, the greater the required amount of fast frequency response.

[0051] FIG. 4 is a flowchart showing the process of the inertia center distance calculation unit 14. First, in step S11, the inertia center distance calculation unit 14 reads the system equipment database 41, the calculation results of the system simulation unit 12, and the calculation results of the pre-correction area frequency index calculation unit 13, and proceeds to step S12. In step S12, the inertia center distance calculation unit 14 calculates the inertia center frequency f COI is calculated according to equation (1).

number

[0052] Here, M i is the inertia constant of the synchronous generator i. n is the number of synchronous generators. f i is the frequency at synchronous generator i.

[0053] In step S13, the inertia center distance calculation unit 14 assigns 1 to a variable k. In step S14, the inertia center distance calculation unit 14 calculates the uncorrected area frequency index f k and the center of inertia frequency f calculated in step S12 COI Using the above, the center of inertia distance index Q k The distance index Q of the center of inertia in the partial system area k is calculated. k The method of deriving the area frequency index f before correction may be any of the following formulas (2) to (4). k and the center of inertia frequency f COI It may also be another function that uses as a variable.

number

[0054]

number

[0055]

number

[0056] In step S14, the inertia center distance calculation unit 14 calculates the pre-correction area frequency index f k For all subsystem areas k corresponding to k If the calculation has been performed for all the partial system areas k (Yes), the process in FIG. 4 ends. If the calculation has not been performed for any partial system area k (No), the inertia center distance calculation unit 14 adds 1 to the variable k (step S16) and returns to step S14. The inertia center distance calculation unit 14 repeats the processes of steps S14 to S16, whereby the inertia center distances in all partial system areas k can be obtained.

[0057] 5 is a graph showing an example of the calculation results of the area frequency index and the center of inertia frequency. The horizontal axis of the graph represents time, and the vertical axis of the graph represents frequency. Here, the graph in Fig. 5 shows the frequency of each partial system area in which each inverter device is located, calculated by the pre-correction area frequency index calculation unit 13, and the inertia center frequency calculated by the inertia center distance calculation unit 14. Here, the area frequency index f k indicates the frequency at nodes 160C to 160E in power system 20 to which the inverter devices are connected.

[0058] Moreover, the partial system area in which node 160C is located is referred to as partial system area 1, and the frequency of partial system area 1 is indicated by a thick dashed line. The partial system area in which node 160D is located is referred to as partial system area 2, and the frequency of partial system area 2 is indicated by a thin solid line. The partial system area in which node 160E is located is referred to as partial system area 3, and the frequency of partial system area 3 is indicated by a thin dashed line.

[0059] The frequency of the partial system area 1 shown by the thick dashed line is closest to the inertia center frequency shown by the thick solid line. And the frequency of the partial system area 2 shown by the thin solid line is farthest from the inertia center frequency. From this, the inertia center distance index Q of each partial system area calculated by the inertia center distance calculation unit 14 is k It can be seen that the inertia center distance index Q2 of the partial system area 2 is the largest, and the inertia center distance index Q1 of the partial system area 1 is the smallest.

[0060] Next, a process executed by the control priority determination unit 15 and the inertia center distance priority database 53 will be described. The control priority determination unit 15 determines the inertia center distance index Q k are sorted in descending order and stored in the inertia center distance ranking database 53 together with the control object and the controllable amount of the high-speed frequency response of the corresponding partial system area k.

[0061] FIG. 6 is a diagram showing an example of the configuration of the inertia center distance ranking database 53 for any contingency fault. The inertial center distance ranking database 53 is the inertial center distance index Q k The information on the control areas is arranged in descending order of the control amount of the high-speed frequency response. The inertia center distance ranking database 53 stores the controllable amount of the high-speed frequency response in each partial system area (area controllable amount), the control target capable of high-speed frequency response, and the controllable amount of the high-speed frequency response for each device. Here, the controllable amount of the high-speed frequency response is the active power that can be output as a high-speed frequency response out of the active power that each device can output, and is available from the inverter characteristics database 42.

[0062] In addition, when the operating status of the target inverter device can be confirmed from the system measurement value database 44, the area controllable amount is stored. The area controllable amount indicates the total value of the controllable amount of the high-speed frequency response by device in each partial system area. Note that n in the table is the center of inertia distance index Q k The ranking of each partial system area corresponding to the size of the center of inertia distance index Q k The values ​​of n are expressed as n=1, 2, ... in ascending order of controllability. In addition, m in the table indicates the ranking of each partial system area corresponding to the smallest controllable amount of each device in the partial system area, and m=1, 2, ... in ascending order of controllable amount.

[0063] Here, the objects to be controlled with high-speed frequency response are listed as follows: BESS (Battery Energy Storage System) and PV (Photovoltaic power generation) in partial system area 2, WF (Wind Farm) and STATCOM (Static Synchronous Compensator) in partial system area 3, and WF and HVDC (High Voltage Direct Current) in partial system area 1.

[0064] 7 is a flowchart showing the process of the control content determination unit 16. The definitions of n and m in the following description are the same as those in FIG. First, in step S21, the control content determination unit 16 reads the frequency response control value database 45, the system measurement value database 44, and the inertia center distance ranking database 53, and then proceeds to step S22.

[0065] In step S22, the control content determination unit 16 refers to the system inertia at the time stored in the system measurement value database 44, and uses the information stored in the frequency response control value database 45 to determine the required amount P FFR Determine. In step S23, the control content determination unit 16 assigns 1 to the variable m. In step S24, the control content determination unit 16 assigns 1 to the variable n. In step S25, the control content determination unit 16 uses the device-specific controllable amount P(n,m) stored in the inertia center distance ranking database 53 to determine the total control amount P SUM Calculate.

[0066]

number

[0067] In step S26, the control content determination unit 16 determines the total control amount P SUM is the required amount of fast frequency response P FFR The control content determination unit 16 determines whether the total control amount P SUM is the required amount of fast frequency response P FFR If it exceeds the total control amount P SUM is the required amount of fast frequency response P FFR If it does not exceed (No), the process proceeds to step S27.

[0068] In step S26, the control content determination unit 16 judges whether the variable n is equal to the maximum value nmax. If the variable n is equal to the maximum value nmax, the control content determination unit 16 proceeds to step S29. If the variable n is not equal to the maximum value nmax (No), the control content determination unit 16 adds 1 to the variable n (step S28) and returns to step S25.

[0069] In step S29, the control content determination unit 16 judges whether the variable m is equal to the maximum value mmax. If the variable m is equal to the maximum value mmax, the control content determination unit 16 proceeds to step S31. If the variable m is not equal to the maximum value mmax (No), the control content determination unit 16 adds 1 to the variable m (step S30) and returns to step S24.

[0070] In step S31, the control content determination unit 16 stores the control targets and controllable amounts P(1,1) to P(n,m) in the fast frequency response control content database 52.

[0071] By the processing of steps S21 to S31, the inverter device for implementing high-speed frequency response and its control amount can be determined. Here, the processing of the control content decision unit 16 for fast frequency response to an arbitrary supply-demand imbalance accident ΔP=600 [MW] will be specifically explained with reference to Figures 3, 6 and 7. In the following examples, it is assumed that the system inertia at the target time recorded in the system measurement value database 44 is 20,000 [MWs], and the contents stored in the frequency response control value database 45 and the inertia center distance ranking database 53 are as shown in Figures 3 and 6.

[0072] In step S21, the system inertia of 20,000 [MWs] stored in the system measurement value database 44 is referenced to the frequency response control value database 45 shown in FIG. 3 to obtain the required amount P FFR is determined to be 160 [MW]. Next, the control content determination unit 16 repeats the processes of steps S24 to S30. SUM= 170 [MW], and P FFR = 160 [MW], the process proceeds to step S31.

[0073] In step S31, the control objects and controllable amounts from P(1,1) to P(3,1) are organized as control contents for assumed accidents as shown in FIG.

[0074] Fig. 8 is a diagram showing an example of the configuration of the fast frequency response control content database 52 for any contingency fault. The difference from the configuration of the fast frequency response control content database 52 shown in Fig. 6 is that the row for HVDC (High Voltage Direct Current) in the partial system area 1 is deleted. Since the control content decision unit 16 controls only the amount required for fast frequency response, it is possible to reduce the amount of control required for stabilization.

[0075] As described above, the fault condition setting unit 11 to the frequency stabilization calculation unit 18 each repeat the process, and store the output system data group 5 for all assumed faults stored in the fault relay database 43. The output system data group 5 is pre-determined at a predetermined cycle, such as 5 minutes or 30 minutes. The output system data group 5 may be recalculated and updated at a cycle that matches the update of the input system data group 4, or may be updated at a cycle different from that of the input system data group 4. If the recalculation is performed at the same cycle as the input system data group 4 and the output system data group 5 is updated, it is possible to determine the control content of the high-speed frequency response and the stabilization control content using information that is as new as the input system data group 4. On the other hand, if the calculation is performed at a timing independent of the input system data group 4, it is possible to secure sufficient calculation time and precisely determine the control content.

[0076] When a fault occurs, the type of fault is identified based on the fault relay information, and a control command is sent to the stored control object using the information in the high-speed frequency response control content database 52 and the stabilization control content database 54 corresponding to that fault, thereby enabling frequency stabilization in each partial system area following a system fault. In this way, by grasping the frequency fluctuations in each partial system area during a system accident and determining the control content of multiple inverter devices with high-speed frequency response within the power system, and by determining the current control amount and negative control amount taking into account the high-speed frequency response, it is possible to stabilize the frequency of the power system including renewable energy power sources.

[0077] In addition, by providing a display unit 31 that displays information relating to one or more of the area frequency index database 51, the inertia center distance ranking database 53, the high-speed frequency response control content database 52, and the stabilization control content database 54 on a screen, various information can be provided to the operator of the power system frequency stabilization device 10.

[0078] FIG. 9 is a diagram showing a processing functional configuration of a power system frequency stabilization device according to the second embodiment. The power system frequency stabilization device according to the second embodiment will be described with reference to Fig. 9. Note that the same reference numbers are used for functional blocks common to the first embodiment.

[0079] The power system frequency stabilization device 10 according to the second embodiment is composed of the functions of a system simulation unit 12, a pre-correction area frequency index calculation unit 13, an inertia center distance calculation unit 14, a control priority determination unit 15, and a control content determination unit 16, as well as an input system data group 4 and an output system data group 5.

[0080] After a system fault occurs, the power system frequency stabilization device 10 according to the second embodiment executes the functions of a system simulation unit 12, a pre-correction area frequency index calculation unit 13, an inertia center distance calculation unit 14, a control priority determination unit 15, and a control content determination unit 16 under fault conditions based on fault relay information, and sends a control command to the control target based on information in a fast frequency response control content database 52. In this way, the frequency stabilization device 10 makes it possible to stabilize the frequency of each partial system area following a system fault.

[0081] According to the present invention, it is possible to stabilize the frequency of a power system including renewable energy power sources. In addition, by controlling in consideration of the distribution of inertia of the entire system, the amount of control of power sources and loads required for stabilizing the frequency can be reduced, making it possible to suppress power outages and costs due to load restrictions. Furthermore, it is possible to quantify the contribution of the high-speed frequency response of the inverter power source to maintaining the frequency, making it possible to provide incentives, which will increase power generation revenue for power generation companies and provide a system stabilization effect for system operators.

[0082] The present invention will now be described. (1) an inverter device (110A, 110B, 120A, 120B, 130A, 120C, 140A) that connects an electric output to a power grid (20) and has a high-speed frequency response capability that allows the electric output to be adjusted within 10 seconds, preferably within 2 seconds, when the frequency of the power grid (20) fluctuates; a pre-correction area frequency index calculation unit (13) that calculates an evaluation index of a frequency fluctuation for each partial system area set in the power system (20) based on a position of the inverter device; a control content determination unit (16) that determines a control amount of the inverter device using an installation node of the inverter device, data on frequency response, data on a required amount of high-speed frequency response in the power system (20), and a calculation result of an evaluation index of frequency fluctuation for each partial system area; a post-correction area frequency stability determination unit (17) that determines whether or not an evaluation index of frequency fluctuation for each partial system area falls within a specified range; A frequency stabilization device for a power system comprising:

[0083] As a result, in the event of a system fault, it becomes possible to control the inverter device and suppress an increase in local frequency fluctuation that may occur due to differences in the distribution of inertia within the system.

[0084] (2) a frequency stabilization calculation unit (18) that calculates control amounts of loads and generators for the power system (20) when the post-correction area frequency stability determination unit (17) determines that the evaluation index of frequency fluctuation for each partial system area is equal to or greater than a specified range; The frequency stabilization device for a power system according to (1) is characterized in that it comprises:

[0085] This makes it possible, in the event of a grid fault, to utilize the loads and generators to suppress increases in local frequency fluctuations that may occur due to differences in the distribution of inertia within the grid.

[0086] (3) The evaluation index of the frequency fluctuation is a frequency or a rate of change of frequency (RoCoF) at a generator or a bus in the power system (20), The power system frequency stabilization device according to (2) is characterized in that

[0087] This makes it possible to appropriately evaluate frequency fluctuations in partial system areas.

[0088] (4) the control content determination unit (16) calculates an inertia center frequency of the power system (20), and determines a control content of the inverter device using the inertia center frequency and a calculation result of the pre-correction area frequency index calculation unit (13). The power system frequency stabilization device according to (3) above.

[0089] This makes it possible to calculate the distance between the frequency of each partial system area and the center of inertia frequency of the entire power system, and makes it possible to determine control content that takes into account differences in the distribution of inertia within the power system and the resulting increases in local frequency fluctuations.

[0090] (5) A control priority determination unit (15) is further provided that determines a priority order of the plurality of inverter devices using a center of inertia frequency of the power system (20) and a result of the corrected area frequency stability determination unit (17), The control content determination unit (16) determines the inverter device to be controlled and the control amount based on the priority order determined by the control priority determination unit (15). The power system frequency stabilization device according to (3) above.

[0091] As a result, inverter devices with higher priority are targeted for control in descending order of priority, making it possible to more effectively suppress frequency fluctuations in each partial system area.

[0092] (6) the control content determination unit (16) determines control content of the inverter device based on data related to system equipment installed in the power system (20), an operating status of the inverter device in the power system (20), and inertia measured in the power system (20); The power system frequency stabilization device according to (1) is characterized in that

[0093] This enables the control content determining section (16) to appropriately determine the control content of the inverter device.

[0094] (7) a display unit (31) that displays on a screen any of the information calculated by the pre-correction area frequency index calculation unit (13), the control content determination unit (16), the post-correction area frequency stability determination unit (17), and the frequency stabilization calculation unit (18); The power system frequency stabilization device according to (2) above, further comprising:

[0095] This allows the operator of the frequency stabilization device to conveniently grasp the current state of the power system.

[0096] (8) a step in which a pre-correction area frequency index calculation unit calculates an evaluation index of frequency fluctuation for each partial system area set in the power system (20) based on data related to inertia in the power system (20) and using as a reference the positions of inverter devices (110A, 110B, 120A, 120B, 130A, 120C, 140A) having a high-speed frequency response capable of adjusting an electric output within 10 seconds, preferably within 2 seconds; a control content determination unit (16) connecting an electric output to the power system (20) and determining a control amount of the inverter device during a frequency fluctuation of the power system (20) by using an installation node of the inverter device, data related to frequency response, data related to a required amount of high-speed frequency response in the power system (20), and a calculation result of an evaluation index of frequency fluctuation for each partial system area; a step of determining whether or not an evaluation index of frequency fluctuation for each partial system area falls within a specified range by a post-correction area frequency stability determination unit (17); A method for stabilizing a frequency of a power system comprising:

[0097] As a result, in the event of a system fault, it becomes possible to control the inverter device and suppress an increase in local frequency fluctuation that may occur due to differences in the distribution of inertia within the system.

[0098] (9) a step of calculating an evaluation index of frequency fluctuation for each partial system area set in the power system (20) based on data on inertia in the power system (20) and using as a reference the positions of inverter devices (110A, 110B, 120A, 120B, 130A, 120C, 140A) having a high-speed frequency response capable of adjusting an electric output within 10 seconds, preferably within 2 seconds; a step of connecting an electric output to the power system (20), and determining a control amount of the inverter device during a frequency fluctuation of the power system (20) using an installation node of the inverter device, data on frequency response, data on a required amount of high-speed frequency response in the power system (20), and a calculation result of an evaluation index of frequency fluctuation for each partial system area; a step of determining whether or not an evaluation index of frequency fluctuation for each partial system area falls within a specified range; A power system frequency stabilization program that causes a computer to execute the above.

[0099] As a result, in the event of a system fault, it becomes possible to control the inverter device and suppress an increase in local frequency fluctuation that may occur due to differences in the distribution of inertia within the system.

[0100] <<Variation>> The present invention is not limited to the above-described embodiment, and includes various modified examples. For example, the above-described embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to those having all of the configurations described. It is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0101] The above configurations, functions, processing units, processing means, etc. may be realized in part or in whole by hardware such as an integrated circuit. The above configurations, functions, etc. may be realized by software by a processor interpreting and executing a program that realizes each function. Information such as the program, table, file, etc. that realizes each function can be stored in a recording device such as a memory, a hard disk, or an SSD (Solid State Drive), or a recording medium such as a flash memory card or a DVD (Digital Versatile Disk).

[0102] In each embodiment, the control lines and information lines are those that are considered necessary for the explanation, and not all control lines and information lines in the product are necessarily shown. In reality, it may be considered that almost all components are connected to each other. [Explanation of symbols]

[0103] 10 Frequency Stabilizer 11 Accident condition setting section 12 System Simulation Section 13 Pre-correction area frequency index calculation section 14 Center of inertia distance calculation section 15 Control Priority Determination Unit 16 Control content determination unit 17 Corrected area frequency stability judgement section 18 Frequency stabilization calculation section 110A, 110B Synchronous generator 120A, 120B, 120C Renewable energy power sources 130A storage battery 140A Self-excited reactive power compensator 150A, 150B, 150C, 150D, 150E Transformers 160A, 160B, 160C, 160D, 160E, 160F, 160G nodes 170A,170B,170C,170D,170E,170F,170G power transmission line 180A,180B load 190 DC Power Transmission System 20 Power system 300 Communication Network 31 Display section 32 Input section 33 Communications Department 34 CPU 35 Memory 36 Bus Line 4 Input data set 41 System equipment database 42 Inverter characteristics database 44 System Measurement Data Database 45 Frequency response control value database 43 Fault Relay Database 5 Output data set 51 Area Frequency Index Database 53 Center of Inertia Distance Ranking Database 52 High-speed frequency response control content database 54 Stabilization Control Contents Database

Claims

1. an inverter device that connects an electric output to a power grid and has a high-speed frequency response capability that allows the electric output to be adjusted within 10 seconds, preferably within 2 seconds, when the frequency of the power grid fluctuates; a pre-correction area frequency index calculation unit that calculates an evaluation index of a frequency fluctuation for each partial system area set in the power system based on a position of the inverter device; a control content determination unit that determines a control amount of the inverter device by using an installation node of the inverter device, data on frequency response, data on a required amount of high-speed frequency response in the power system, and a calculation result of an evaluation index of frequency fluctuation for each partial system area; a post-correction area frequency stability determination unit that determines whether an evaluation index of a frequency fluctuation for each partial system area falls within a specified range; A frequency stabilization device for a power system comprising:

2. a frequency stabilization calculation unit that calculates a control amount of a load and a generator for the power system when the post-correction area frequency stability determination unit determines that the evaluation index of the frequency fluctuation for each partial system area is equal to or greater than a specified range; The power system frequency stabilization device according to claim 1, further comprising:

3. The evaluation index of the frequency fluctuation is the frequency or rate of change of frequency (RoCoF) at a generator or bus in the power system; 3. The power system frequency stabilization device according to claim 2.

4. the control content determination unit calculates an inertia center frequency of the power system, and determines a control content of the inverter device using the inertia center frequency and a calculation result of the pre-correction area frequency index calculation unit.

4. The power system frequency stabilization device according to claim 3.

5. A control priority determination unit that determines a priority order of the plurality of inverter devices using a center of inertia frequency of the power system and a result of the correction area frequency stability determination unit, The control content determination unit determines an inverter device to be controlled and a control amount based on the priority order determined by the control priority determination unit.

4. The power system frequency stabilization device according to claim 3.

6. the control content determination unit determines control content of the inverter device based on data related to system equipment installed in the power system, an operating status of the inverter device in the power system, and inertia measured in the power system; 2. The power system frequency stabilization device according to claim 1 .

7. a display unit that displays on a screen any of the information calculated by the pre-correction area frequency index calculation unit, the control content determination unit, the post-correction area frequency stability determination unit, and the frequency stabilization calculation unit; 3. The power system frequency stabilization device according to claim 2, further comprising:

8. A step in which a pre-correction area frequency index calculation unit calculates an evaluation index of frequency fluctuation for each partial system area set in the power system based on data on inertia in the power system, using a position of an inverter device with a high-speed frequency response that can adjust an electric output within 10 seconds, preferably within 2 seconds, as a reference; a control content determination unit connecting the electric output to the power system, and determining a control amount of the inverter device during a frequency fluctuation of the power system, using an installation node of the inverter device, data on frequency response, data on a required amount of high-speed frequency response in the power system, and a calculation result of an evaluation index of frequency fluctuation for each partial system area; a step of determining whether or not an evaluation index of frequency fluctuation for each partial system area falls within a specified range by a post-correction area frequency stability determination unit; A method for stabilizing a frequency of a power system comprising:

9. calculating an evaluation index of frequency fluctuation for each partial system area set in the power system based on data on inertia in the power system and using as a reference the position of an inverter device having a fast frequency response capable of adjusting an electric output within 10 seconds, preferably within 2 seconds; a step of connecting an electric output to the power system, and determining a control amount of the inverter device during a frequency fluctuation of the power system, using an installation node of the inverter device, data on a frequency response, data on a required amount of high-speed frequency response in the power system, and a calculation result of an evaluation index of a frequency fluctuation for each partial system area; a step of determining whether or not an evaluation index of frequency fluctuation for each partial system area falls within a specified range; A power system frequency stabilization program that causes a computer to execute the above.

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