JP7553288B2 - CONTROL DEVICE AND LOAD CONTROL METHOD - Google Patents

Description

Article 30, Paragraph 2 of the Patent Act applies [1] ▲1▼Publication date March 1, 2020 (Web publication period: March 6, 2020 to August 28, 2020) ▲2▼Publications Ordinance Proceedings of the 2020 National Conference of the Institute of Electrical Engineers of Japan, pp. 124-125 Published by the Institute of Electrical Engineers of Japan (Web public URL: https://gakkai-web.net/iee/program/2020/index.html) <References ＞ Information on publication of papers presented at the 2020 National Conference of the Institute of Electrical Engineers of Japan 2020 <References> Collection of papers presented at the 2020 National Conference of the Institute of Electrical Engineers of Japan Published papers [2] ▲1▼Publication date August 28, 2020 ▲2▼Published thing Proceedings of the 2020 Electrical Engineering Society Conference on Electric Power and Energy, 1WEB2-1 to 1WEB2-10, Published by the Institute of Electrical Engineers of Japan (Web URL: https://www.iee.jp/pes/b_event/r02/ https ://gakkai-web.net/p/pes/pes/mod2.php) <Materials> Information on the publication of presentation papers at the 2020 Electrical Engineering Society of Japan Power and Energy Division Conference <Materials> Information on the publication of presentation papers at the 2020 Electrical Engineering Society of Japan Power and Energy Division Conference Papers published in the Energy Society Conference Proceedings

The present invention relates to a control device and a load control method.

The importance of strengthening the resilience of power grids has been reaffirmed in the wake of large-scale power outages caused by natural disasters. In addition, with the growing demand for decarbonization, it is expected that renewable energy sources (hereinafter referred to as "renewable energy sources") will become the main source of power in the future.

In order to achieve both enhanced resilience and decarbonization in future power grids, it will be important to develop frequency control technology that can appropriately deal with the loss of renewable energy sources, which is a concern as a factor in reducing frequency stability when frequencies fluctuate significantly during disasters and other such events. As a recent frequency control technology, a method for setting under-frequency relays that takes into account a variety of grid conditions is disclosed in the following non-patent document 1.

Turaj. Amraee, Mohammad. Ghaderi. Darebaghi, Alireza. Soroudi and Andrew. Keane, "Probabilistic Under Frequency Load Shedding Considering RoCoF Relays of Distributed Generators," in IEEE Transactions on Power Systems, vol. 33, no. 4, pp. 3587 -3598 (2018).

However, because the amount of renewable energy source dropout varies depending on the output of the renewable energy source at the time, i.e., the amount of solar radiation and wind speed, it is thought that it will become difficult to respond appropriately to the dropout of renewable energy sources using conventional frequency control technology.

The present invention was made in consideration of these circumstances, and its purpose is to suppress the decline in frequency stability caused by a supply shortage resulting from the disconnection of renewable energy sources.

(1) One aspect of the present invention is a control device that stabilizes the frequency of a power grid to which renewable energy sources and loads are connected, and in the event that one or more of the renewable energy sources are lost, the control device eliminates the imbalance in power supply and demand by disconnecting one or more of the loads from the power grid.

(2) In the grid stabilization system of (1) above, when the renewable energy power source is lost, the control device may disconnect the load from the power grid in an amount corresponding to the amount of the renewable energy power source lost.

(3) In the control device of (2) above, when the renewable energy power source is lost, the control device may disconnect the load from the power grid with a load control amount equivalent to the amount of the renewable energy power source lost.

(4) The control device of (3) above may include a characteristic generating unit that determines a renewable energy shedding characteristic that indicates the amount of shedding of the renewable energy power source according to the rate of change of the frequency of the power grid based on the output of the renewable energy power source, and a control unit that disconnects a load of the load control amount that is equivalent to the amount of shedding of the renewable energy power source from the power grid in accordance with the renewable energy shedding characteristic generated by the characteristic generating unit.

(5) In the control device of (4) above, a frequency undercut relay that performs load shedding is provided in each load feeder of the power system, and the control unit may adjust a setting value of the frequency undercut relay so as to disconnect from the power system a load of the load control amount equivalent to the amount of shedding of the renewable energy power source in accordance with the renewable energy shedding characteristics generated by the characteristic generation unit.

(6) In the control device of (5) above, the control unit may include a control target selection unit that selects a control target from among the load feeders in which the frequency down relay that performs the load shedding is provided, based on the load amount of each load feeder and the output of the renewable energy power source, and an adjustment unit that adjusts the setting value of the control target selected by the control target selection unit to disconnect from the power grid a load of the load amount equivalent to the amount of shedding of the renewable energy power source in accordance with the renewable energy shedding characteristics.

(7) In the control device of (6) above, the adjustment unit may disable the load shedding function of an under-frequency relay other than the control target selected by the control target selection unit.

(8) One aspect of the present invention is a load control method for stabilizing the frequency of a power grid to which renewable energy power sources and loads are connected, and in the event that one or more of the renewable energy power sources are lost, the load control method eliminates the imbalance in power supply and demand by disconnecting one or more of the loads from the power grid.

As described above, the present invention can suppress the deterioration of frequency stability caused by a supply shortage resulting from the disconnection of a renewable energy source.

1 is a configuration diagram of a power system to which a power system stabilization system according to a first embodiment is applied; FIG. 2 is a diagram illustrating each functional unit of the control device according to the first embodiment. FIG. 2 is a diagram illustrating the renewable energy shedding characteristics of the first embodiment. FIG. 4 is a flow diagram of the operation of the control device of the first embodiment. 1A to 1C are diagrams illustrating the effects of the first embodiment. FIG. 11 is a configuration diagram of a power system to which a power system stabilization system according to a second embodiment is applied. FIG. 11 is a diagram illustrating each functional unit of a control device according to a second embodiment. FIG. 11 is a flow diagram of the operation of the control device according to the second embodiment.

The grid stabilization system according to this embodiment will be described below with reference to the drawings.

First Embodiment
1 is a configuration diagram of a power system 100 to which a power system stabilization system according to a first embodiment is applied. The power system 100 includes various facilities such as renewable energy power sources, transmission lines, and transformers. As an example, the power system 100 includes a main system 10, a substation 11, a first bus 12, a plurality of load feeders 13-k (k=1, 2, ... -n) (n is an integer of 2 or more), and a plurality of lower systems 14-k. In the following description, the symbols following the hyphens may be omitted.

The substation 11 supplies power from the main system 10, which is a system higher than the substation 11, to each of the lower systems 14, which are systems lower than the substation 11. In this embodiment, a case is described in which the power system 100 has two substations 11, but the number is not particularly limited.

The first busbar 12 is a busbar located in a substation and is connected to the substation 11. In this embodiment, the first busbar 12 is connected to each substation 11.

The load feeder 13-k is a connection line that connects the first busbar 12 and the lower system 14-k.

The downstream system 14-k includes, for example, a second busbar 20-k, one or more renewable energy sources 30-k, and one or more loads 40-k.

One or more renewable energy power sources 30-k and one or more loads 40-k are connected to the second busbar 20-k. In the example shown in FIG. 1, one renewable energy power source 30-k is electrically connected to the second busbar 20-k, but this is not limited thereto, and the number of renewable energy power sources 30-k connected to the second busbar 20-k may be more than one. Similarly, in the example shown in FIG. 1, one load 40-k is electrically connected to the second busbar 20-k, but this is not limited thereto, and the number of loads 40-k connected to the second busbar 20-k may be more than one.

The renewable energy power source 30-k is a power source that uses renewable energy, such as solar power generation or wind power generation. As an example, the renewable energy power source 30-k has a solar power generation device 32-k and a power conditioner system (PCS) 31-k.

The PCS 31-k converts the DC power generated by the power generation device 32-k into AC power. The DC power converted by the PCS 31-k is supplied to the main system 10 and the load 40-k. The PCS 31-k has an islanding operation detection function that detects islanding operation, for example, by a change in frequency on the load side, and stops the output of the renewable energy power source 30-k. Specifically, when the supply capacity of the power system 100 is insufficient and the power supply and demand become unbalanced, the frequency of the power system 100 decreases. The greater the imbalance in the power supply and demand, the greater the change rate (df/dt) of the frequency of the power system 100. Therefore, as an islanding operation detection function, the PCS 31-k stops the output of the renewable energy power source 30-k when the change rate (df/dt) of the frequency becomes equal to or exceeds a predetermined value. In the following description, the stop of the output of the renewable energy power source 30 by the islanding operation detection function is referred to as "dropout".

The load 40-k is, for example, an electrical device at a consumer's facility.

The power grid stabilization system of the first embodiment includes multiple load-side under frequency relays (UFRs) 200-k and a control device 300.

The UFR 200-k is provided in the load feeder 13-k. When the UFR 200-k operates from a conductive state (on state) to a cut-off state (off state), the sub-system 14-k is disconnected from the main system 10. In other words, when the UFR 200-k operates from a conductive state (on state) to a cut-off state (off state), a load shedding is performed in which the load 40-k included in the sub-system 14-k is disconnected from the main system 10. In this embodiment, the UFR 200-k is provided for each load feeder.

The UFR200-k detects frequency changes on the load side, etc. In response to the rare risk of a significant drop in frequency due to a supply capacity shortage caused by a large-scale power source failure, etc., the UFR200-k implements emergency measures to restore frequency by shedding loads to a range where the frequency can be controlled by the supply capacity (power generation side) excluding the power source that has been lost.

For example, to prevent chain reaction power trips or large-scale blackouts caused by frequency drops, the frequency level and its duration are set as several stages of set values in the UFR200-k, and if the time during which the frequency on the load side falls below a preset level continues for a preset duration, load shedding is performed sequentially.

The UFR200-k has a load shedding function that performs load control according to the frequency change rate and its duration. Specifically, in the load shedding function, the frequency change rate and its duration are set as set values, and when the time during which the frequency change rate on the load side is equal to or greater than a preset level continues for the preset duration, the UFR200-k changes from a conductive state (on state) to a cutoff state (off state) and shedding the load.

The setpoint of UFR 200-k may be adjusted by control device 300. In addition, the load shedding function of UFR 200-k may be enabled and disabled by control device 300.

When one or more renewable energy power sources 30 are dropped, the control device 300 eliminates the imbalance in power supply and demand by disconnecting one or more loads 40 from the power system 100. For example, when a renewable energy power source 30 is dropped, the control device 300 disconnects the loads 40 from the power system 100 according to the amount of dropped renewable energy power sources 30. The amount of dropped renewable energy power sources 30 is information indicating the total amount of power whose supply from the renewable energy power sources 30 to the power system 100 has been stopped due to the dropout of the renewable energy power sources 30. In other words, the amount of dropped power is the amount of power whose supply from the aggregate (renewable energy aggregate) to the power system 100 has been stopped when all renewable energy power sources 30 connected to the power system 100 are considered as one aggregate. For example, when the renewable energy power source 30 is lost, the control device 300 disconnects from the power grid 100 the amount of power of the load 40 (hereinafter referred to as the "load control amount") that is approximately the same as the amount of power lost by the renewable energy power source 30.

The control device 300 is connected to each UFR 200-k via wire or wirelessly.

The functional parts of the control device 300 are described below with reference to FIG. 2. FIG. 2 is a diagram illustrating each functional part of the control device 300.

The control device 300 includes a data acquisition unit 310, a characteristic generation unit 320, and a control unit 330. These components are realized, for example, by a hardware processor such as a CPU (Central Processing Unit) executing a program (software). In addition, some or all of these components may be realized by hardware (including circuitry) such as an LSI (Large Scale Integrated circuit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be realized by collaboration between software and hardware. The program may be stored in advance in a storage device such as an HDD (Hard Disk Drive) or a flash memory (a storage device having a non-transient storage medium), or may be stored in a removable storage medium such as a DVD or CD-ROM (a non-transient storage medium), and may be installed in the storage device by mounting the storage medium in a drive device. The storage device may be composed of, for example, a HDD, flash memory, EEPROM (Electrically Erasable Programmable Read Only Memory), ROM (Read Only Memory), or RAM (Random Access Memory).

The data acquisition unit 310 acquires output data of each renewable energy power source 30 in real time. Then, the data acquisition unit 310 calculates the total value of the acquired output of each renewable energy power source 30. Hereinafter, the output of the renewable energy aggregate, i.e., the total value, is referred to as "renewable energy output." Here, the renewable energy output may be a measured value or an estimated value based on the amount of solar radiation, etc. In this embodiment, real time does not need to be completely simultaneous, and may include a time lag due to communication via a network, etc.

The data acquisition unit 310 acquires data on the load (demand), which is the amount of electricity for each load 40, in real time.

The characteristic generating unit 320 generates a renewable energy dropout characteristic that indicates the amount of dropout of the renewable energy power source 30 according to the frequency change rate of the power grid 100 based on the renewable energy output data acquired by the data acquiring unit 310. FIG. 3 is a diagram showing an example of the renewable energy dropout characteristic of this embodiment, and is a graph of the renewable energy dropout characteristic.

The horizontal axis of the graph shown in FIG. 3 is the frequency change rate, and the vertical axis is the amount of renewable energy power source dropout. The amount of renewable energy power source dropout shown in FIG. 3 indicates the percentage of power from renewable energy power sources whose supply to the power system 100 has been stopped due to dropout, assuming that the system demand is 100%. As shown in FIG. 3, the renewable energy dropout characteristic has a feature that the amount of dropout increases as the frequency change rate increases, and when the frequency change rate reaches a certain value, the amount of dropout saturates. That is, FIG. 3 shows that as the frequency change rate increases, the number of renewable energy power sources 30 that drop out increases, and when the frequency change rate reaches a certain value, the remaining renewable energy power sources 30 that have not dropped out drop out all at once, and all of the renewable energy power sources 30 drop out.

The renewable energy dropout characteristics are expressed by superimposing the dropout characteristics of each renewable energy power source 30. Therefore, by aggregating the logic and settings of the islanding detection function of the renewable energy power sources in the target area and their ratios, it is possible to express the collective renewable energy dropout characteristics of the renewable energy power sources 30 in the same area. Here, the renewable energy dropout characteristics are characterized by the islanding detection function. Therefore, the type and number of renewable energy sources that drop out for a certain frequency change rate do not change. On the other hand, since the renewable energy output constantly changes depending on the amount of solar radiation and wind speed, the amount of dropout relative to the frequency change when the renewable energy power source 30 drops out also constantly changes accordingly. Therefore, the characteristic generation unit 320 generates the renewable energy dropout characteristics as appropriate based on the constant renewable energy output obtained in real time.

As an example, the characteristic generating unit 320 obtains in advance dropout information indicating the type and number of renewable energy power sources 30 that drop out for a certain frequency change rate from a data sheet that consolidates the logic and setting values of the islanding detection function of each PCS 31 and their ratios, and stores the dropout information. Then, the characteristic generating unit 320 generates renewable energy dropout characteristics based on the dropout information and the real-time renewable energy output obtained by the data acquiring unit 310. For example, when the renewable energy output is 100%, the characteristic generating unit 320 generates the renewable energy dropout characteristics shown by the dotted line in FIG. 3, and when the renewable energy output is 50%, the characteristic generating unit 320 generates the renewable energy dropout characteristics shown by the solid line in FIG. 3. Note that the characteristic generating unit 320 may generate the information on the renewable energy dropout characteristics in a table format or by a formula.

The control unit 330 adjusts the setting value of each UFR 200 so that an amount of power equivalent to the amount of shedding is disconnected from the power grid 100 as a load control amount in accordance with the renewable energy shedding characteristics generated by the characteristic generation unit 320. Here, the amount of shedding of the renewable energy shedding characteristics can be regarded as a load control amount. In other words, the renewable energy shedding characteristics indicate a load control amount for a frequency change. In other words, the characteristic generation unit 320 generates a load control amount for a frequency change rate (hereinafter referred to as a "load control amount characteristic") by generating a renewable energy shedding characteristic. For example, taking the load control amount characteristic shown by the dotted line in FIG. 3 as an example, the control unit 330 selects a UFR 200 to be controlled from among the multiple UFRs 200 so as to disconnect from the power system 100 an amount of power equivalent to 8% of the system demand at 1 Hz/s as the load control amount, and an amount of power equivalent to 14% of the system demand at 2 Hz/s as the load control amount, and adjusts the setting value of the selected UFR 200. In this way, the control unit 330 adjusts the setting value of the UFR 200 based on the load control amount characteristic, thereby optimizing the load control amount according to the amount of renewable energy dropout in various system states.

The functional parts of the control unit 330 are described below. The control unit 330 includes a control target selection unit 340 and an adjustment unit 350.

The control target selection unit 340 selects a control target, which is a UFR 200 that performs load shedding, based on information including the load amount of each load 40 acquired by the data acquisition unit 310. As an example, the control target selection unit 340 selects a control target, which is a UFR 200 that performs load shedding, based on the load amount of each load 40 acquired by the data acquisition unit 310 and the output of each renewable energy power source 30, so as to achieve the load control amount characteristic generated by the characteristic generation unit 320.

The adjustment unit 350 adjusts the setpoint of the control object selected by the control object selection unit 340 so that the load shedding function of the UFR 200 realizes the above-mentioned load control amount characteristic. The adjustment unit 350 may also disable the load shedding function of the UFR 200 for control objects other than those selected by the control object selection unit 340.

For example, it is assumed that the load control amount characteristics at 100% renewable energy output can be realized by disconnecting two load feeders, i.e., two downstream systems 14, from the main system 10 every 0.5 Hz/s. In that case, for example, the adjustment unit 350 adjusts each of the setting values of UFR200-1 and UFR200-2 to 0.5 Hz/s, each of the setting values of UFR200-3 and UFR200-4 to 1 Hz/s, and each of the setting values of UFR200-5 and UFR200-6 to 1.5 Hz/s. For example, when the renewable energy output changes from 100% to 50%, the adjustment unit 350 disables the load shedding function by UFR 200-2 out of UFR 200-1 and UFR 200-2, disables the load shedding function by UFR 200-4 out of UFR 200-3 and UFR 200-4, and disables the load shedding function by UFR 200-6 out of UFR 200-5 and UFR 200-6. This allows the control unit 330 to realize a load control amount characteristic that changes according to the renewable energy output.

The flow of the calculation process in the control device 300 of the first embodiment will be described below with reference to FIG. 4. FIG. 4 is a flow diagram of the calculation process in the control device 300 of the first embodiment. The control device 300 repeats the calculation process shown in FIG. 4 at regular intervals.

The control device 300 acquires the output data of the renewable energy power source 30 of each load feeder in a certain area and the load amount data of each load 40 in real time (step S101). Then, the control device 300 calculates the total value (renewable energy output) of the output data of each renewable energy power source 30, and generates a load control amount characteristic based on the total value (step S102). The control device 300 calculates the load amount of the lower system 14 for each lower system 14 (for each load feeder) based on the output data of each renewable energy power source 30 and the load amount of each load 40 (step S103). That is, the control device 300 calculates the load amount of the lower system 14-k by subtracting the output of the renewable energy power source 30-k from the load amount of the load 40-k. Here, the load amount of the lower system 14-k may be measured. The control device 300 selects the UFR 200 (control target) to be subjected to load shedding according to the frequency change rate based on the load control amount characteristics and the load amount for each lower system 14 so as to shedding the load in accordance with the load control amount characteristics generated in step S102 (step S104), and adjusts the setting value of the selected UFR 200 (step S105).

For example, when the frequency change rate becomes 1 Hz/s, the load control amount (dropout amount of the renewable energy power source 30) becomes 15 MW, and when the frequency change rate becomes 2 Hz/s, the load control amount is added by 10 MW to become 25 MW, and a load control amount characteristic is generated. Also, assuming that the load amount of the load 40-1 is 10 MW and the output of the renewable energy power source 30-1 is 5 MW, the load amount of the lower system 14-1 becomes 5 MW. Also, assuming that the load amount of the load 40-2 is 20 MW and the output of the renewable energy power source 30-2 is 5 MW, the load amount of the lower system 14-2 becomes 15 MW. Also, assuming that the load amount of the load 40-3 is 5 MW and the output of the renewable energy power source 30-3 is 0 MW, the load amount of the lower system 14-3 becomes 5 MW. In such a case, the control device 300 adjusts the setting value of UFR 200-2 to 1 Hz/s in order to disconnect 15 MW from the power system 100 as a load control amount when the frequency change rate becomes 1 Hz/s according to the load control amount characteristics. Also, in order to disconnect a further 10 MW from the power system 100 as a load control amount when the frequency change rate becomes 2 Hz/s, the control device 300 adjusts each setting value of UFR 200-1 and UFR 200-3 to 2 Hz/s. Then, the control device 300 disables the load shedding function of UFR 200 other than UFR 200-1 to UFR 200-3. This allows the control device 300 to eliminate the imbalance in power supply and demand caused by a supply capacity shortage due to the disconnection of a renewable energy source, contributing to the stabilization of the frequency of the power system 100.

The effects of the first embodiment will be described. Figure 5(a) is a diagram showing the results of load control by a conventional grid stabilization system. In the conventional grid stabilization system, the UFR performs load shedding using the frequency level as a setpoint. Figure 5(b) is a diagram showing the results of load control by the grid stabilization system of the first embodiment.

As shown in FIG. 5(a), in a conventional grid stabilization system, there is a large control delay in response to the dropout of a renewable energy power source 30, resulting in a lack of control, making it difficult to reduce the amount of dropout of the renewable energy power source 30 or improve the frequency bottom.

As shown in FIG. 5(b), in the grid stabilization system of the first embodiment, both the control delay and the insufficient amount of control in response to the dropout of the renewable energy power source 30 are significantly improved, the amount of dropout of the renewable energy power source 30 is reduced, and the frequency bottom is also significantly improved. In addition, the grid stabilization system of the first embodiment is capable of high-speed and appropriate load control in response to the dropout of the renewable energy power source 30, so the amount of load control is also reduced (the control effect is obtained with less load control than before).

As described above, the control device 300 of the first embodiment eliminates the imbalance in power supply and demand by disconnecting one or more loads 40 from the power grid 100 when one or more renewable energy power sources 30 are lost. With this configuration, the control device 300 can suppress a decrease in frequency stability caused by a supply capacity shortage caused by the loss of a renewable energy power source 30.

The control device 300 of the first embodiment also adjusts the set value of the UFR 200 so as to disconnect the load 40 with a load control amount equivalent to the amount of shedding from the power grid 100 in accordance with the renewable energy shedding characteristics generated based on the renewable energy output. This enables control coordination with conventional control that responds to power source shedding excluding renewable energy power sources.

Second Embodiment
6 is a configuration diagram of a power system 100 to which a power system stabilization system of the second embodiment is applied. The power system stabilization system differs from the first embodiment in that a relay such as a circuit breaker is provided for each load feeder 13 instead of a UFR 200. In the following description, parts having the same functions as those described in the first embodiment are given the same names and symbols, and specific descriptions of the functions are omitted.

The power grid stabilization system of the second embodiment includes multiple relays 400-k and a control device 300A.

The relay 400-k is provided in the load feeder 13-k. When the relay 400-k changes from a conductive state (on state) to a cut-off state (off state), the lower system 14-k is disconnected from the main system 10.

The control device 300A controls each of the multiple relays 400-k to an on or off state. When one or more renewable energy power sources 30 are lost, the control device 300A eliminates the imbalance in power supply and demand by disconnecting one or more loads 40 from the power system 100. When a renewable energy power source 30 is lost, the control device 300A disconnects from the power system 100 the loads 40 that correspond to the amount of renewable energy power sources 30 that have been lost.

The functional parts of the control device 300A are described below with reference to FIG. 7. FIG. 7 is a diagram illustrating each functional part of the control device 300A.

The control device 300A includes a data acquisition unit 310, a characteristic generation unit 320, and a control unit 330A.

The functional parts of the control unit 330A are described below. The control unit 330A includes a control target selection unit 340A and an adjustment unit 350A.

The control target selection unit 340A selects a control target from among the load feeders in which the relay 400 is installed, based on information including the load amount of each load 40 acquired by the data acquisition unit 310. As an example, the control target selection unit 340A selects a control target corresponding to the frequency change rate based on the load amount of the load 40 of each load feeder acquired by the data acquisition unit 310 and the output of the renewable energy power source 30, so that the load control amount characteristic generated by the characteristic generation unit 320 is realized.

The adjustment unit 350A controls each of the multiple relays 400-k to an on or off state so that the above-mentioned load control amount characteristic is realized. For example, the adjustment unit 350A controls the relay 400 to be the control target selected by the control target selection unit 340A to be in the off state.

For example, it is possible to realize the load control amount characteristic at 100% renewable energy output by disconnecting two load feeders, i.e., two downstream systems 14, from the main system 10 every 0.5 Hz/s. In this case, for example, the adjustment unit 350A controls relays 400-1 and 400-2 to the off state when the frequency change rate becomes 0.5 Hz/s, and further controls relays 400-3 and 400-4 to the off state when the frequency change rate becomes 1 Hz/s. In this way, the control unit 330A can realize the load control amount characteristic that changes according to the renewable energy output.

The flow of operation of the control device 300A of the second embodiment will be described below with reference to FIG. 8. FIG. 8 is a flow diagram of the operation of the control device 300A of the second embodiment. Steps S201 to S203 are the same as steps S101 to S103 in FIG. 4, and therefore will not be described.

The control device 300A selects a relay 400 (control target) to be subjected to load shedding according to the frequency change rate based on the load amount for each lower system 14 so as to shedding the load in accordance with the load control amount characteristics generated in step S102 (step S204), and controls the selected relay 400 to the off state according to the frequency change rate obtained in real time (step S205).

For example, when the frequency change rate becomes 1 Hz/s, the load control amount (the amount of dropout caused by the dropout of the renewable energy power source 30) becomes 15 MW, and when the frequency change rate becomes 2 Hz/s, the load control amount is increased by 10 MW to 25 MW, and a load control amount characteristic is generated. Also, assuming that the load amount of the load 40-1 is 10 MW and the output of the renewable energy power source 30-1 is 5 MW, the load amount of the lower system 14-1 becomes 5 MW. Also, assuming that the load amount of the load 40-2 is 20 MW and the output of the renewable energy power source 30-2 is 5 MW, the load amount of the lower system 14-2 becomes 15 MW. Also, assuming that the load amount of the load 40-3 is 5 MW and the output of the renewable energy power source 30-3 is 0 MW, the load amount of the lower system 14-3 becomes 5 MW. In such a case, the control device 300A controls the relay 400-2 to the off state when the frequency change rate becomes 1 Hz/s in order to disconnect 15 MW from the power system 100 as the load control amount when the frequency change rate becomes 1 Hz/s according to the load control amount characteristics. The control device 300A also controls the relays 400-1 and 400-3 to the off state when the frequency change rate becomes 2 Hz/s in order to disconnect an additional 10 MW from the power system 100 as the load control amount when the frequency change rate becomes 2 Hz/s. This allows the control device 300A to eliminate the imbalance in power supply and demand caused by a supply shortage due to the disconnection of a renewable energy power source, contributing to the stabilization of the frequency of the power system 100.

The control device 300A of the second embodiment described above can achieve the same effects as the first embodiment.

The above describes an embodiment of the present invention in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and includes designs that do not deviate from the gist of the present invention.

For example, when selecting a control target, which is a UFR 200 that performs load shedding, based on the load amount of the load 40 of each load feeder and the output of the renewable energy power source 30, the control target selection unit 340 may preferentially select a lower system 14 with a large load amount within a range that does not exceed the load control amount of the load control amount characteristic. For example, assume that a load control amount characteristic is generated in which the load control amount is 10 MW when the frequency change rate is 1 Hz/s. In this case, if the load amount of the lower system 14-1 is 5 MW, the load amount of the lower system 14-2 is 5 MW, and the load amount of the lower system 14-3 is 10 MW, the control target selection unit 340 selects the lower system 14-3, which has the largest load amount of the lower system 14, as the control target at a frequency change rate of 1 Hz/s. That is, the control target selection unit 340 can realize the load control amount characteristic even if it selects the lower systems 14-1 and 14-2 as the control targets with a frequency change rate of 1 Hz/s, but it may select the lower system 14-3 as the control target in order to realize the load control amount characteristic with less control. This makes it possible to minimize the number of UFRs 200 that adjust the setting value.

The term "unit" in the specification means a unit that processes at least one function or operation, which may be embodied as hardware or software, or a combination of hardware and software.

1, 1A... Power system stabilization system, 300, 300A... Control device, 310... Data acquisition unit, 320, 320A... Characteristics generation unit, 330, 330A... Control unit, 340, 340A... Control target selection unit, 350, 350A... Adjustment unit

Claims (5)

A control device that stabilizes the frequency of a power system to which a renewable energy power source and a load are connected,
A characteristic generating unit that generates a renewable energy shedding characteristic indicating an amount of shedding of the renewable energy power source according to a frequency change rate of the power grid based on an output of the renewable energy power source obtained in real time;
A control unit that, when one or more of the renewable energy power sources are dropped, eliminates an imbalance in power supply and demand by disconnecting the load from the power grid with a load control amount equivalent to the amount of the dropped renewable energy power sources in accordance with the renewable energy dropout characteristics generated by the characteristic generation unit;
A control device comprising : an under frequency relay for performing load shedding is provided at each load feeder of the power system;
The control unit adjusts a setting value of the frequency down relay so as to disconnect a load of the load control amount equivalent to the amount of shedding of the renewable energy power source from the power grid in accordance with the renewable energy shedding characteristic generated by the characteristic generation unit.
The control device according to claim 1 . The control unit is
A control target selection unit that selects a control target from among the load feeders in which the frequency down relay that performs the load shedding is provided, based on the load amount of each of the loads and the output of each of the renewable energy power sources;
an adjustment unit that adjusts a setting value of the control object selected by the control object selection unit to separate from the power grid a load of the load control amount that is approximately the same as the amount of the renewable energy shedding in accordance with the renewable energy shedding characteristics;
Equipped
The control device according to claim 2 . The adjustment unit disables a load shedding function of an under-frequency relay other than the control target selected by the control target selection unit.
The control device according to claim 3 . A load control method for stabilizing a frequency of a power system to which a renewable energy power source and a load are connected,
Generate a renewable energy shedding characteristic indicating an amount of shedding of the renewable energy power source according to a frequency change rate of the power grid based on an output of the renewable energy power source obtained in real time;
When one or more of the renewable energy power sources are dropped, the load with a load control amount equivalent to the amount of the dropped renewable energy power sources is disconnected from the power grid in accordance with the generated renewable energy dropout characteristics , thereby eliminating the imbalance in power supply and demand.
Load control methods.

Images