Control server, power system, and control method

Abstract

This control server comprises a reception unit that receives information indicating the voltage of a power system, and a control unit that controls a distributed power supply connected to the power system and a compensation device disposed in the power system. The compensation device is a device that supplies reactive power to the power system. The control unit controls the reactive power supplied from the compensation device on the basis of the information indicating the voltage of the power system, and controls the power factor of the distributed power supply in accordance with the reactive power supplied from the compensation device.

Description

Control Server, Power System, and Control Method

[0001] The present disclosure relates to a control server, a power system, and a control method.

[0002] In an environment where distributed power sources are connected to a power grid, a technology for stabilizing the power grid by arranging a Static Var Compensator (SVC) in the power grid is known.

[0003] Furthermore, in a case where a Step Voltage Regulator (SVR) is arranged in a power grid, a technology has been proposed that calculates a set value for the SVR based on the voltage of a node arranged downstream of the SVR in the power grid, on the assumption that reactive power output from the SVC is stopped (for example, Patent Document 1).

[0004] Japanese Unexamined Patent Application Publication No. 2024-126846

[0005] An aspect of the disclosure is a control server including: a receiving unit that receives information indicating a voltage of a power grid; and a control unit that controls a distributed power source connected to the power grid and a compensator arranged in the power grid, wherein the compensator is a device that outputs reactive power to the power grid, and the control unit controls the reactive power output from the compensator based on the information indicating the voltage of the power grid, and controls a power factor of the distributed power source in accordance with the reactive power output from the compensator.

[0006] An aspect of the disclosure is a power system including: a distributed power source connected to a power grid; a compensator arranged in the power grid; and a control server that controls the distributed power source and the compensator, wherein the compensator is a device that outputs reactive power to the power grid, and the control server receives information indicating a voltage of the power grid, controls the reactive power output from the compensator based on the information indicating the voltage of the power grid, and controls a power factor of the distributed power source in accordance with the reactive power output from the compensator.

[0007] The embodiment of the disclosure is a control method comprising: step A receiving information indicating the voltage of a power system; and step B controlling distributed power sources connected to the power system and compensation devices arranged in the power system, wherein the compensation devices are devices that contribute reactive power to the power system, and step B includes the steps of controlling the reactive power contributed from the compensation devices based on information indicating the voltage of the power system, and controlling the power factor of the distributed power sources in accordance with the reactive power contributed from the compensation devices.

[0008] Figure 1 shows a power system 1 according to an embodiment. Figure 2 shows a control server 40 according to an embodiment. Figure 3 shows an operation example 1 according to an embodiment. Figure 4 shows an operation example 2 according to an embodiment. Figure 5 shows an operation example 2 according to an embodiment. Figure 6 shows an operation example 2 according to an embodiment. Figure 7 shows an operation example 3 according to an embodiment.

[0009] Embodiments will be described below with reference to the drawings. In the following drawings, identical or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic.

[0010] [Embodiment] (1) Power System The power system according to the embodiment will be described below. As shown in Figure 1, the power system 1 includes a substation 10, a power node 30, a compensation device 35, a control server 40, and a business operator system 50.

[0011] Substation 10 is connected to the power grid (hereinafter referred to as the first power grid 11). Substation 10 may be managed by a power transmission and distribution company.

[0012] In the following, a location on the power system that is far from substation 10 may be referred to as downstream. A location on the power system that is close to substation 10 may be referred to as upstream.

[0013] For example, the first power system 11 branches at point A, and one of the first power systems 11 after branching at point A may have a transformer 21A, while the other first power system 11 after branching at point A may have a point B. The first power system 11 branches at point B, and one of the first power systems 11 after branching at point B may have a transformer 21B, while the other first power system 11 after branching at point B may have a point C. The first power system 11 branches at point C, and one of the first power systems 11 after branching at point C may have a transformer 21C, while the other first power system 11 after branching at point C may have a transformer 21D. Transformers 21A to 21D may be collectively referred to as transformer 21.

[0014] Here, in the first power system 11, measuring instrument 22A may be placed between point A and point B. In the first power system 11, measuring instrument 22B may be placed between point B and point C. In the first power system 11, measuring instrument 22C may be placed between point C and point D. Measuring instruments 22A to 22C may be collectively referred to as measuring instrument 22. In the first power system 11, at least one of measuring instruments 22A to 22C may be placed.

[0015] Transformer 21 is connected to the first power system 11 upstream of transformer 21 and converts the voltage of the first power system 11. Downstream of transformer 21, transformer 21 is connected to power node 30 via a power system (hereinafter referred to as the second power system 12).

[0016] For example, transformer 21A and power node 30A are connected by a second power system 12A, transformer 21B and power node 30B are connected by a second power system 12B, transformer 21C and power node 30C are connected by a second power system 12C, and transformer 21D and power node 30D are connected by a second power system 12D.

[0017] The measuring instrument 22 measures the voltage of the first power system 11. The measuring instrument 22 may also measure the current of the first power system 11. The measuring instrument 22 may be managed by the power transmission and distribution company. The measuring instrument 22 may also be a next-generation Smart Meter.

[0018] Figure 1 illustrates a case where three measuring instruments 22 are arranged, but only one measuring instrument 22 may be arranged in the first power system 11. Furthermore, there may be two measuring instruments 22, or four or more, arranged in the first power system 11.

[0019] Power node 30 is connected to the second power system 12. Power node 30 may have devices that consume power, or it may have devices that generate power. The devices that consume power may be called load devices. The devices that generate power may be called distributed power sources.

[0020] For example, power nodes 30A1 and 30A2 may be connected to the second power system 12A. Power node 30A2 may have a distributed power source composed of a power generator 31A2 and a PCS (Power Conditioning System) 32A2. Power nodes 30B1 and 30B2 may be connected to the second power system 12B. Power node 30B1 may have a distributed power source composed of a power generator 31B1 and a PCS 32B1. Power nodes 30C1 and 30C2 may be connected to the second power system 12C. Power node 30C1 may have a distributed power source composed of a power generator 31C1 and a PCS 32C1. Power node 30C2 may have a distributed power source composed of a power generator 31C2 and a PCS 32C2. Power nodes 30D1 and 30D2 may be connected to the second power system 12D. Power node 30D1 may have a distributed power source consisting of a power generator 31D1 and a PCS 32D1. Power nodes 30A1 to 30D2 may be collectively referred to as power node 30. Power generators 31A2 to 31D1 may be collectively referred to as power generator 31. PCS 32A2 to PCS 32D1 may be collectively referred to as PCS 32.

[0021] The power generation devices 31A2 to 31D1 may be power generation devices that generate electricity using renewable energy. That is, the distributed power source including power generation devices 31A2 to 31D1 may be an example of a distributed power source connected to a power grid. Renewable energy may include solar, wind, water, geothermal, biomass, etc. Typically, power generation devices 31A2 to 31D1 may be solar cells.

[0022] Here, the power generation devices 31A2 to 31D1 may be of different sizes. Although not particularly limited, power generation devices 31A2, 31B1, and 31C1 may be small-scale power generation devices, power generation device 31C2 may be a medium-scale power generation device larger than power generation devices 31A2 and 31B1, and power generation device 31D1 may be a large-scale power generation device larger than power generation device 31C2.

[0023] The compensation device 35 may be located in the second power system 12. The compensation device 35 can be any device that provides reactive power. The compensation device 35 has the function of monitoring the voltage of the second power system 12 and provides reactive power so that the voltage of the second power system 12 does not deviate from a predetermined range. This also suppresses situations in which the voltage of the first power system 11 deviates from a predetermined range. For example, the compensation device 35 may be a static reactive power compensator (SVC) or an inverter device (e.g., PCS).

[0024] For example, compensation device 35A may be installed in the second power system 12A, compensation device 35B in the second power system 12B, compensation device 35C in the second power system 12C, and compensation device 35D in the second power system 12D. Compensation devices 35A to 35D may be collectively referred to as compensation device 35.

[0025] The control server 40 is a server that controls the distributed power supply (hereinafter referred to as PCS32) and compensation device 35 of the power node 30. The control server 40 may be managed by a business operator that manages the distributed power supply of the power node 30 (for example, a specified electric utility company, a resource aggregator, etc.).

[0026] The operator system 50 is a system that manages the power grid (the first power grid 11 and the second power grid 12). The operator system 50 may be an example of a higher-level system that manages the power grid. The operator system 50 may monitor the status of the power grid (e.g., voltage, current, etc.) based on information received from the measuring instrument 22. The operator system 50 may be a system that is responsible for stabilizing the power grid. The operator system 50 may delegate some of the functions for stabilizing the power grid to the control server 40. The operator system 50 may be managed by a power transmission and distribution operator.

[0027] (2) Control Server The control server according to the embodiment will be described below. As shown in Figure 2, the control server 40 has a communication unit 41, a management unit 42, and a control unit 43.

[0028] The communication unit 41 is comprised of a communication module. The communication module may be a wireless communication module compliant with standards such as IEEE 802.11a / b / g / n / ac / ax, ZigBee, Wi-SUN, LTE, 5G, or 6G, or it may be a wired communication module compliant with standards such as IEEE 802.3.

[0029] The communication unit 41 may communicate with the measuring instrument 22. For example, the communication unit 41 may receive information from the measuring instrument 22 indicating the status of the power system (first power system 11), such as voltage. The information indicating the status of the power system may be called power flow information.

[0030] The communication unit 41 may communicate with the PCS32. For example, the communication unit 41 may send a control command to the PCS32 instructing it to change the power factor of the PCS32.

[0031] The communication unit 41 may communicate with the compensation device 35. For example, the communication unit 41 may transmit a control command to the compensation device 35 instructing it to contribute reactive power. The control command may include information indicating the amount of reactive power to be contributed.

[0032] The communication unit 41 may communicate with the operator system 50. For example, the communication unit 41 may receive information from the operator system 50 indicating the status (e.g., voltage) of the power system (first power system 11). The communication unit 41 may transmit information to the operator system 50 requesting permission to receive information indicating the status of the power system from the measuring instrument 22. The communication unit 41 may transmit request information to the operator system 50 requesting a change in the power factor of the distributed power source. The communication unit 41 may receive response information from the operator system 50 granting permission to change the power factor of the distributed power source.

[0033] The management unit 42 is composed of storage media such as HDDs (Hard Disk Drives), SSDs (Solid State Drives), and non-volatile memory.

[0034] The management unit 42 may manage the distributed power sources of the power node 30. For example, the management unit 42 may manage the rating information of the power generator 31, or it may manage the rating information of the PCS 32.

[0035] The control unit 43 may include at least one processor. The at least one processor may consist of a single integrated circuit (IC) or a plurality of communicatively connected circuits (such as integrated circuits and / or discrete circuits).

[0036] The control unit 43 may control the distributed power supply (PCS 32) and compensation device 35 of the power node 30.

[0037] Firstly, the control unit 43 may control the reactive power supplied by the compensation device 35 based on information indicating the voltage of the power system. For example, the control unit 43 may instruct the compensation device 35 to supply or increase reactive power if the voltage of the power system (first power system 11) may exceed the upper limit of a predetermined range. The amount of reactive power supplied or increased may be determined by the control unit 43 based on the magnitude of the voltage to be reduced. Alternatively, the control unit 43 may instruct the compensation device 35 to stop supplying or reduce reactive power if the voltage of the power system (first power system 11) may exceed the upper limit of a predetermined range. The amount of reactive power reduced may be determined by the control unit 43 based on the magnitude of the voltage to be increased.

[0038] Secondly, the control unit 43 may control the power factor of the distributed power supply (PCS32) in accordance with the reactive power supplied from the compensation device 35. For example, the control unit 43 may instruct the PCS32 to increase the power factor of the distributed power supply (PCS32) when it confirms that reactive power has been supplied from the compensation device 35. The control unit 43 may also instruct the PCS32 to increase the power factor of the distributed power supply (PCS32) when it receives response information that permits a change in the power factor of the distributed power supply.

[0039] For example, the default power factor of PCS32 may be a value less than 1 (e.g., 0.8). The default power factor of PCS32 may also be determined by an agreement with the transmission and distribution operator. In such cases, the power factor of PCS32 may be changed to a value greater than the default value if permission is obtained from the transmission and distribution operator.

[0040] In this embodiment, the communication unit 41 may be configured as a receiving unit that receives information indicating the voltage of the power system. The control unit 43 may be configured as a control unit that controls distributed power sources connected to the power system and compensation devices placed in the power system. The communication unit 41 may also be configured as a transmitting unit that transmits request information to a higher-level system (operator system 50) that manages the power system, requesting a change in the power factor of the distributed power sources.

[0041] (3) Examples of Operation Below, we will explain some examples of operation. The following are some possible examples of operation.

[0042] (3.1) Operation Example 1 In Operation Example 1, a case where the power factor of PCS 32 is changed will be described.

[0043] As shown in FIG. 3, in step S10, the control server 40 receives power flow information from the operator system 50. The power flow information may include information indicating a voltage of an electric power system. The control server 40 may receive the power flow information from the measuring instrument 22. The control server 40 may receive the power flow information from the measuring instrument 22 after obtaining approval from a power transmission and distribution business operator.

[0044] In step S11, the control server 40 tentatively calculates a reactive power contribution amount of the compensating device 35 and an increase amount (improvement amount) of the power factor of the PCS 32 on the basis of the power flow information. Specifically, the control server 40 tentatively calculates the reactive power contribution amount of the compensating device 35 and the increase amount (improvement amount) of the power factor of the PCS 32 such that the voltage of the electric power system does not deviate from a predetermined range.

[0045] In step S12, the control server 40 transmits request information requesting a change of the power factor of the PCS 32 to the operator system 50. The request information may include a result of the tentative calculation in step S11.

[0046] In step S13, the operator system 50 determines whether to approve the change of the power factor of the PCS 32. Description here continues for the case where the change of the power factor of the PCS 32 is approved.

[0047] In step S14, the control server 40 receives, from the operator system 50, response information that approves the change of the power factor of the PCS 32.

[0048] In step S20, the control server 40 transmits a control command (contribution instruction) instructing reactive power contribution to the compensating device 35. The contribution instruction may include information indicating the reactive power contribution amount.

[0049] In step S21, the compensating device 35 contributes reactive power.

[0050] In step S22, the control server 40 receives a contribution response from the compensation device 35, which includes information indicating that reactive power has been contributed. The contribution response may also include information indicating that the amount of reactive power specified by the contribution instruction has been contributed.

[0051] In step S23, the control server 40 may send a control command (power factor instruction) to the PCS32 instructing it to change the power factor of the PCS32. For example, the power factor instruction may include information indicating a power factor greater than the default value.

[0052] In step S24, PCS32 applies the power factor indicated by the power factor instruction. For example, PCS32 may apply a power factor greater than the default value.

[0053] In Operation Example 1, it is assumed that the compensator 35 that supplies reactive power and the PCS 32 that changes the power factor are connected to the same second power system 12. For example, in the example shown in Figure 1, when reactive power is supplied from compensator 35A, the power factor of PCS 32A2 is changed; when reactive power is supplied from compensator 35B, the power factor of PCS 32B1 is changed; when reactive power is supplied from compensator 35C, the power factor of at least one of PCS 32C1 or PCS 32C2 is changed; and when reactive power is supplied from compensator 35D, the power factor of PCS 32D1 is changed.

[0054] (3.2) Operation Example 2 Operation Example 2 describes a case in which a communication failure occurs between the control server 40, PCS 32, and compensation device 35. Operation Example 2 may be an operation example that presupposes Operation Example 1, or it may be an operation example that does not presuppose Operation Example 1. The following options are possible for Operation Example 2.

[0055] Option 2-1 describes a case where a communication failure occurs between the control server 40 and one or more compensation devices 35, but no communication failure occurs between the control server 40 and the remaining compensation devices 35. Compensation devices 35 that experience a communication failure with the control server 40 are referred to as compensation device 35 (failed), and compensation devices 35 that do not experience a communication failure with the control server 40 are referred to as compensation device 35 (normal). Compensation device 35 (failed) is an example of a first compensation device, and compensation device 35 (normal) is an example of a second compensation device.

[0056] As shown in Figure 4, in step S30A, the control server 40 detects a compensation device 35 (faulty) that has experienced a communication failure with the control server 40. Similarly, the compensation device 35 (faulty) detects that it has experienced a communication failure with the control server 40. The control server 40 detects a compensation device 35 (normal) that has not experienced a communication failure with the control server 40.

[0057] In step S30X, the compensator 35 (fault) autonomously controls the contribution of reactive power so that the voltage of the power system does not deviate from a predetermined range.

[0058] In step S31A, the control server 40 calculates the amount of reactive power to be contributed to compensate for the power grid shortage (insufficient reactive power), assuming that the compensation device 35 (fault) operates autonomously. The insufficient reactive power can be considered as the difference between the reactive power that the compensation device 35 (fault) was contributing under the control of the control server 40 and the reactive power that the compensation device 35 (fault) is expected to contribute autonomously.

[0059] In step S32A, the control server 40 transmits a control command (compensation instruction) to the compensation device 35 (normal) instructing it to compensate for the reactive power supplied by the compensation device 35 (faulty). Here, compensation for the reactive power of the compensation device 35 (faulty) means compensation for the insufficient reactive power as described above.

[0060] Here, the control server 40 may preferentially allocate the compensation contribution amount for compensating for the insufficient reactive power to the compensation device 35 (normal) that is closer to the compensation device 35 (faulty) on the power grid.

[0061] For example, if the compensation device 35 (normal) closest to the compensation device 35 (faulty) is able to contribute the entire compensation amount, the entire compensation amount may be allocated to the compensation device 35 (normal) closest to the compensation device 35 (faulty). On the other hand, if the compensation device 35 (normal) closest to the compensation device 35 (faulty) is not able to contribute the entire compensation amount, the maximum compensation amount may be allocated to the compensation device 35 (normal) closest to the compensation device 35 (faulty), and the remaining compensation amount may be allocated to the compensation device 35 (normal) second closest to the compensation device 35 (faulty).

[0062] Alternatively, the control server 40 may allocate larger compensation contributions to the compensation devices 35 (normal) that are closer to the compensation devices 35 (fault) on the power grid. The amount of compensation contributions to each compensation device 35 (normal) may be determined by the control server 40.

[0063] In step S33A, the compensation device 35 (normal) controls the contribution of reactive power. Specifically, the compensation device 35 (normal) contributes reactive power according to the amount of compensation contribution allocated to the compensation device 35 (normal).

[0064] In step S34A, the control server 40 receives a compensation response from the compensation device 35 (normal) in response to the compensation instruction. The compensation response may include information indicating the amount of compensation to be provided by the compensation device 35 (normal).

[0065] In step S35A, the control server 40 predicts the maximum and minimum power demand values ​​of the power node 30. The prediction may be based on historical power demand values. Based on the maximum and minimum power demand values ​​of the power node 30, the control server 40 calculates the voltage fluctuation range of the power system.

[0066] For example, the lower limit of the power system voltage may be determined by the maximum power demand of power node 30, and the upper limit of the power system voltage may be determined by the minimum power demand of power node 30. The voltage fluctuation range of the power system may be defined by the difference between the lower limit and the upper limit of the power system voltage.

[0067] Furthermore, the control server 40 determines the power factor of the PCS 32 based on the voltage fluctuation range of the power system. In addition to the voltage fluctuation range of the power system, the control server 40 may also determine the power factor of the PCS 32 based on the difference between the insufficient reactive power and the compensation contribution (the compensation contribution actually provided by the compensation device 35 (normal)).

[0068] In step S36A, the control server 40 may send a control command (power factor instruction) to the PCS32 instructing it to change the power factor of the PCS32. Basically, the power factor instructed by the power factor instruction may be smaller than the default value, or it may be larger than the default value. In the case of instructing a power factor larger than the default value, permission from the power transmission and distribution operator may be required, as in operation example 1.

[0069] In step S37A, PCS32 applies the power factor indicated by the power factor instruction.

[0070] In step S40, the control server 40 and the compensation device 35 (fault) detect the recovery of the communication failure.

[0071] In step S41, the control server 40 may send a control command (power factor instruction) to the PCS32 instructing it to change the power factor of the PCS32. The power factor instructed by the power factor instruction may be the power factor that was applied before the communication failure occurred.

[0072] In step S42, the PCS32 applies the power factor indicated by the power factor indicator.

[0073] Option 2-2 describes a case where a communication failure occurs between the control server 40 and all compensation devices 35. In other words, it describes a case where no compensation devices 35 (normal) that are not experiencing a communication failure with the control server 40 are detected.

[0074] As shown in Figure 5, in step S30B, the control server 40 detects the compensation device 35 (fault) that has experienced a communication failure with the control server 40. Similarly, the compensation device 35 (fault) detects that it has experienced a communication failure with the control server 40.

[0075] In step S30X, the compensator 35 (fault) autonomously controls the contribution of reactive power so that the voltage of the power system does not deviate from a predetermined range.

[0076] In step S31B, the control server 40 calculates the amount of reactive power to be contributed to compensate for the power grid shortage (insufficient reactive power), assuming that the compensation device 35 (fault) operates autonomously. The insufficient reactive power can be considered as the difference between the reactive power that the compensation device 35 (fault) was contributing under the control of the control server 40 and the reactive power that the compensation device 35 (fault) is expected to contribute autonomously.

[0077] In step S32B, the control server 40 predicts the maximum and minimum power demand values ​​of the power node 30. The prediction may be based on historical power demand values. Based on the maximum and minimum power demand values ​​of the power node 30, the control server 40 calculates the voltage fluctuation range of the power system.

[0078] Furthermore, the control server 40 determines the power factor of the PCS32 based on the voltage fluctuation range of the power system. In addition to the voltage fluctuation range of the power system, the control server 40 may also determine the power factor of the PCS32 based on the insufficient reactive power.

[0079] In step S33B, the control server 40 may send a control command (power factor instruction) to the PCS32 instructing it to change the power factor of the PCS32. Basically, the power factor instructed by the power factor instruction may be smaller than the default value, or it may be larger than the default value. In the case of instructing a power factor larger than the default value, permission from the power transmission and distribution company may be required, as in operation example 1.

[0080] In step S34B, PCS32 applies the power factor indicated by the power factor instruction.

[0081] In step S40, the control server 40 and the compensation device 35 (fault) detect the recovery of the communication failure.

[0082] In step S41, the control server 40 may send a control command (power factor instruction) to the PCS32 instructing it to change the power factor of the PCS32. The power factor instructed by the power factor instruction may be the power factor that was applied before the communication failure occurred.

[0083] In step S42, the PCS32 applies the power factor indicated by the power factor indicator.

[0084] Option 2-3 describes a case in which a communication failure occurs between the control server 40 and all compensation devices 35, and also between the control server 40 and PCS 32.

[0085] As shown in Figure 6, in step S30C, the control server 40 detects the compensation device 35 (fault) that has experienced a communication failure with the control server 40. Similarly, the compensation device 35 (fault) detects that a communication failure has occurred with the control server 40. The PCS 32 detects that a communication failure has occurred with the control server 40.

[0086] In step S30X, the compensator 35 (fault) autonomously controls the contribution of reactive power so that the voltage of the power system does not deviate from a predetermined range.

[0087] In step S31C, the PCS32 calculates the amount of reactive power to be contributed (insufficient reactive power) to compensate for the power grid shortage, assuming that the compensation device 35 (fault) operates autonomously.

[0088] Here, step S31C may be performed in cases where PCS32 is capable of detecting insufficient reactive power. For example, PCS32D1 connected to a large-scale power generation device (e.g., power generation device 31D1 shown in Figure 1) may be capable of detecting insufficient reactive power.

[0089] In step S32C, the PCS32 predicts the maximum and minimum power demand values ​​of the power node 30. The prediction may be based on historical power demand values. The control server 40 calculates the voltage fluctuation range of the power system based on the maximum and minimum power demand values ​​of the power node 30.

[0090] Here, step S32C may be performed in cases where PCS32 is capable of calculating the fluctuation range. For example, PCS32D1 connected to a large-scale power generation device (e.g., power generation device 31D1 shown in Figure 1) may be capable of calculating the fluctuation range.

[0091] Furthermore, the control server 40 determines the power factor of the PCS32 based on the voltage fluctuation range of the power system. In addition to the voltage fluctuation range of the power system, the control server 40 may also determine the power factor of the PCS32 based on the insufficient reactive power.

[0092] In step S33C, PCS32 autonomously applies the determined power factor.

[0093] In step S40, the control server 40 and the compensation device 35 (fault) detect the recovery of the communication failure.

[0094] In step S41, the control server 40 may send a control command (power factor instruction) to the PCS32 instructing it to change the power factor of the PCS32. The power factor instructed by the power factor instruction may be the power factor that was applied before the communication failure occurred.

[0095] In step S42, the PCS32 applies the power factor indicated by the power factor indicator.

[0096] Option 2-3 illustrates a case where PCS32 can determine the insufficient reactive power and calculate its fluctuation range. However, if PCS32 does not have these functions, PCS32 may omit the processing in steps S31C and S32C and apply a predetermined power factor. The predetermined power factor may be a default value.

[0097] Option 2-4 may be a combination of two or more options selected from options 2-1 to 2-3. For example, in option 2-1, if the compensator 35 (normal) cannot fully compensate for the insufficient reactive power, option 2-2 may be added to indicate the power factor of PCS 32.

[0098] (3.3) Operation Example 3 Operation Example 3 describes a case in which the voltage fluctuation range per unit time of the power system (second power system 12) monitored by the compensation device 35 exceeds a threshold. That is, in Operation Example 3, a case in which the voltage of the second power system 12 changes rapidly may be assumed. Operation Example 3 may be an operation example that is based on at least one of Operation Example 1 or Operation Example 2, or it may be an operation example that is not based on Operation Example 1 or Operation Example 2.

[0099] As shown in Figure 7, in step S50, the compensation device 35 detects an event in which the voltage fluctuation per unit time of the second power system 12 exceeds a threshold. For example, such an event may be caused by a sudden increase in the output power of the distributed power source of the power node 30 connected to the second power system 12 to which the compensation device 35 is connected. Alternatively, such an event may be caused by a sudden decrease in the output power of the distributed power source of the power node 30 connected to the second power system 12 to which the compensation device 35 is connected.

[0100] In step S51, the compensation device 35 autonomously contributes reactive power to prevent the voltage of the power system from deviating from a predetermined range.

[0101] In step S52, the compensation device 35 transmits information (fluctuation information) to the control server 40 indicating that a sudden fluctuation in the voltage of the second power system 12 has occurred. The fluctuation information may also include information indicating the fluctuation range per unit time of the voltage of the second power system 12.

[0102] In step S53, the control server 40 prepares to recalculate the set value of the reactive power contribution amount to be contributed by the compensation device 35 based on the fluctuation information. For example, the control server 40 collects information indicating the current amount of reactive power contributed by the compensation device 35 controlled by the control server 40. Note that the compensation device 35 controlled by the control server 40 includes compensation devices 35 other than the compensation device 35 that detected the fluctuation.

[0103] In step S54, the control server 40 sends an information request to the operator system 50. The information request is a message requesting information (power flow information) that indicates the status (e.g., voltage) of the power system (first power system 11).

[0104] In step S55, the operator system 50 acquires tidal current information. For example, the operator system 50 may receive tidal current information from the measuring instrument 22.

[0105] In step S56, the control server 40 receives an information response from the operator system 50 in response to the information request. The information response includes tidal current information.

[0106] In step S57, the control server 40 recalculates the set value for the amount of reactive power contributed by the compensation device 35 based on the power flow information. In addition to the power flow information, the control server 40 recalculates the set value for the amount of reactive power contributed by the compensation device 35 based on the current amount of reactive power contributed by each of the compensation devices 35.

[0107] In step S58, the control server 40 transmits a contribution instruction to the compensation device 35. The contribution instruction includes information indicating the contribution amount set value determined in the recalculation.

[0108] In step S59, the compensation device 35 contributes reactive power according to the contribution amount setting value.

[0109] In step S60, the control server 40 receives a contribution response from the compensation device 35 in response to the contribution instruction. The contribution response may include information indicating that the amount of reactive power specified by the contribution instruction has been contributed.

[0110] In Operation Example 3, the control server 40 may receive power flow information from the measuring instrument 22. The control server 40 may receive power flow information from the measuring instrument 22 after obtaining permission from the power transmission and distribution operator. In such cases, the processing in steps S54 to S56 may be omitted.

[0111] In Operation Example 3, steps S50 to S51 may be considered as operations relating to the control of reactive power over a short period or a localized area. Steps S52 to S60 may be considered as operations relating to the control of reactive power over a long period or a comprehensive area.

[0112] (3.4) In other embodiments, if the voltage of the power system is measured by the measuring instrument 22 to be in danger of deviating from the predetermined range, the control server 40 may control the reactive power of the compensation device 35 closest to the measuring instrument 22 on the power system. The control server 40 may control the reactive power of the compensation device 35 closest to the downstream side of the measuring instrument 22, or it may control the reactive power of the compensation device 35 closest to the upstream side of the measuring instrument 22.

[0113] For example, the control server 40 controls the compensation device 35 to increase reactive power if the voltage of the power system may exceed the upper limit of a predetermined range. The control server 40 controls the compensation device 35 to decrease reactive power if the voltage of the power system may fall below the lower limit of a predetermined range.

[0114] In one embodiment, if the power system voltage measured by the measuring instrument 22 is likely to deviate from a predetermined range, the control server 40 may control the power factor of the PCS 32 closest to the measuring instrument 22 on the power system. The control server 40 may control the power factor of the PCS 32 closest to the measuring instrument 22 downstream, or it may control the power factor of the PCS 32 closest to the measuring instrument 22 upstream.

[0115] For example, the control server 40 controls the PCS32 to decrease the power factor if the voltage of the power system may exceed the upper limit of a predetermined range. The control server 40 controls the PCS32 to increase the power factor if the voltage of the power system may fall below the lower limit of a predetermined range.

[0116] (4) Operation and Effects In the embodiment, the control server 40 may control the reactive power supplied from the compensation device 35 based on information indicating the voltage of the power system, and control the power factor of the PCS 32 in accordance with the reactive power supplied from the compensation device 35 (Operation Example 1). For example, with such a configuration, it is possible to offset the rise in voltage of the power system caused by the increase in the power factor of the PCS 32 with an increase in reactive power, thereby stabilizing the power system while suppressing the disadvantages suffered by businesses that manage distributed power sources (e.g., specific electric utilities, resource aggregators, etc.).

[0117] In this embodiment, when the control server 40 receives response information from the operator system 50 that permits a change in the power factor of the PCS 32, it may control the power factor of the PCS 32 in accordance with the reactive power supplied by the compensator 35. With this configuration, the stabilization of the power grid can be appropriately achieved by leaving the decision regarding changes (especially increases) in the power factor of the PCS 32 to the transmission and distribution operator.

[0118] In this embodiment, the control server 40 may instruct the compensation device 35 (normal) to compensate for the reactive power supplied by the compensation device 35 (faulty) (Option 2-1 in Operation Example 2). With this configuration, even if a communication failure is assumed between the control server 40 and the compensation device 35, the compensation by the compensation device 35 (normal) can appropriately stabilize the power system.

[0119] In this embodiment, the control server 40 may instruct the PCS 32 on the power factor of the PCS 32 when the compensation device 35 (normal) is not present (option 2-2 in operation example 2). With this configuration, even if a communication failure between the control server 40 and the compensation device 35 is assumed, the power system can be appropriately stabilized by controlling the power factor of the PCS 32.

[0120] In this embodiment, the PCS32 may autonomously apply its power factor when a communication failure occurs between the PCS32 and the control server 40 (option 2-3 in Operation Example 2). With this configuration, even when a communication failure is assumed between the PCS32 and the control server 40, the power system can be appropriately stabilized by controlling the power factor of the PCS32.

[0121] In this embodiment, the compensation device 35 may autonomously contribute reactive power to prevent the voltage of the power system from deviating from a predetermined range when the per-unit time fluctuation range of the voltage of the second power system 12 exceeds a threshold (Operation Example 3). With such a configuration, the stabilization of the power system can be appropriately achieved in terms of a short period or a local area.

[0122] (5) Other Embodiments Although the present invention has been described by the embodiments described above, the descriptions and drawings that constitute part of this disclosure should not be understood as limiting the invention. Various alternative embodiments, examples and operational techniques will become apparent to those skilled in the art from this disclosure.

[0123] In the disclosure described above, the measuring instrument 22 is located in the first power system 11, but the disclosure is not limited thereto. The measuring instrument 22 may also be located in the second power system 12.

[0124] In the disclosure described above, the period in which the compensation device 35 operates autonomously may be shorter than the period in which the compensation device 35 is controlled by the control server 40.

[0125] In the disclosure described above, the power node 30 may be read as facility 30.

[0126] In the disclosure described above, "autonomously" may be read as "without being controlled by control commands from the control server 40."

[0127] In the disclosure described above, "reactive power" may include leading reactive power that reduces the voltage of the power system, or lagging reactive power that increases the voltage of the power system. Therefore, the reactive power referred to in the case of reducing the voltage of the power system (for example, the case of increasing the power factor of PCS32 in Operation Example 1) may be interpreted as leading reactive power, and the reactive power referred to in the case of increasing the voltage of the power system may be interpreted as lagging reactive power. Furthermore, the reactive power that reduces the voltage of the power system may be referred to as lagging reactive power, and the reactive power that increases the voltage of the power system may be referred to as leading reactive power.

[0128] It should be noted that the disclosures mentioned above primarily assume reactive power that reduces the voltage of the power grid.

[0129] In the disclosure described above, "contribution of reactive power" may be interpreted as "output of reactive power." That is, "contribution of reactive power" may be interpreted as "output of leading reactive power" or "output of lagging reactive power." "Contribution of reactive power" may be interpreted as "provision of reactive power." That is, "contribution of reactive power" may be interpreted as "provision of leading reactive power" or "provision of lagging reactive power."

[0130] In the disclosure described above, the first power system 11 may be a high-voltage power system, and the second power system 12 may be a low-voltage power system. That is, in the disclosure described above, a low-voltage connection using transformers 21 (transformers 21A to 21D) may be assumed.

[0131] In the above disclosure, at least one of the transformers 21 (transformers 21A to 21D) may not be provided. That is, in the above disclosure, high-voltage connection may be assumed in at least a part of the power system. In the above disclosure, both high-voltage and low-voltage connection may be assumed.

[0132] In the disclosure described above, a power generation device 31 that generates electricity using renewable energy was given as an example of a distributed power source connected to the power grid. However, the disclosure described above is not limited to this. A distributed power source connected to the power grid may also include an energy storage device that performs at least one of charging or discharging.

[0133] Although not specifically mentioned in the disclosure above, a program may be provided that causes a computer to execute each process performed by the control server 40. Furthermore, the program may be recorded on a computer-readable medium. Using a computer-readable medium, it is possible to install the program on a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may include, for example, a CD-ROM or DVD-ROM.

[0134] Alternatively, a chip may be provided comprising a memory for storing programs for executing each process performed by the control server 40, and a processor for executing the programs stored in the memory.

[0135] [Note] The above disclosure may have the following issues and effects. With the spread of distributed power sources that generate electricity using renewable energy, the risk of voltage fluctuations in the power grid deviating from the predetermined range due to reverse power flow from distributed power sources or adverse weather conditions increases, which may lead to the operation of distributed power sources with a power factor smaller than 1 (for example, 0.8).

[0136] However, if distributed power sources are operated with a power factor less than 1, the output power of renewable energy-derived distributed power sources may decrease, potentially causing disadvantages to operators managing distributed power sources (e.g., specified electric utilities, resource aggregators, etc.).

[0137] According to this disclosure, it is possible to provide a control server, a power system, and a control method that enable the stabilization of the power grid while suppressing the disadvantages suffered by businesses that manage distributed power sources.

[0138] The above disclosure may also be expressed as follows: The first feature is a control server comprising: a receiving unit that receives information indicating the voltage of a power system; and a control unit that controls a distributed power source connected to the power system and a compensation device arranged in the power system, wherein the compensation device is a device that contributes reactive power to the power system, and the control unit controls the reactive power contributed from the compensation device based on information indicating the voltage of the power system, and controls the power factor of the distributed power source in accordance with the reactive power contributed from the compensation device.

[0139] The second feature is that, in the first feature, the distributed power source is a control server that includes a device for generating electricity using renewable energy.

[0140] The third feature is a control server which, in the first or second feature, includes a transmitting unit that transmits request information to a higher-level system managing the power grid requesting a change in the power factor of the distributed power sources, the receiving unit receives response information from the higher-level system that permits a change in the power factor of the distributed power sources, and the control unit, upon receiving the response information, controls the power factor of the distributed power sources in accordance with the reactive power supplied by the compensation device.

[0141] The fourth feature is a control server in which, in at least one of the first to third features, the control unit detects a first compensation device which has experienced a communication failure with the control server, and when it detects a second compensation device which has not experienced a communication failure with the control server, it instructs the second compensation device to compensate for the reactive power supplied by the first compensation device.

[0142] The fifth feature is a control server in which, in at least one of the first to fourth features, the control unit detects a first compensation device which has experienced a communication failure with the control server, and does not detect a second compensation device which has not experienced a communication failure with the control server, and instructs the distributed power supply on the power factor of the distributed power supply.

[0143] The sixth feature is a power system comprising: a distributed power source connected to a power grid; a compensation device disposed in the power grid; and a control server that controls the distributed power source and the compensation device, wherein the compensation device is a device that supplies reactive power to the power grid; the control server receives information indicating the voltage of the power grid, controls the reactive power supplied from the compensation device based on the information indicating the voltage of the power grid, and controls the power factor of the distributed power source in accordance with the reactive power supplied from the compensation device.

[0144] The seventh feature is that, in the sixth feature, the distributed power supply is a power system that autonomously applies the power factor of the distributed power supply when it detects a communication failure between the distributed power supply and the control server.

[0145] The eighth feature is a power system in which, in the sixth or seventh feature, the compensation device autonomously contributes the reactive power when the per-unit time fluctuation range of the voltage of the power system monitored by the compensation device exceeds a threshold.

[0146] The ninth feature is that, in the eighth feature, the compensation device is a power system that transmits information to the control server indicating voltage fluctuations associated with an increase in the output power of the distributed power source.

[0147] The tenth feature is a control method comprising: step A, receiving information indicating the voltage of a power system; and step B, controlling a distributed power source connected to the power system and a compensation device arranged in the power system, wherein the compensation device is a device that contributes reactive power to the power system, and step B includes the steps of controlling the reactive power contributed from the compensation device based on information indicating the voltage of the power system, and controlling the power factor of the distributed power source in accordance with the reactive power contributed from the compensation device.

[0148] 1...Power system, 10...Substation, 11...First power system, 12...Second power system, 21...Transformer, 22...Measuring instrument, 30...Power node, 31...Generator, 32...PCS, 35...Compensation device, 40...Control server, 41...Communication unit, 42...Management unit, 43...Control unit, 50...Operator system

Claims

1. A control server comprising: a receiving unit that receives information indicating the voltage of a power system; and a control unit that controls a distributed power supply connected to the power system and a compensation device arranged in the power system, wherein the compensation device is a device that contributes reactive power to the power system; and the control unit controls the reactive power contributed from the compensation device based on information indicating the voltage of the power system, and controls the power factor of the distributed power supply in accordance with the reactive power contributed from the compensation device.

2. The control server according to claim 1, wherein the distributed power source includes a device for generating electricity using renewable energy.

3. A control server according to claim 1 or 2, comprising a transmitting unit that transmits request information to a higher-level system managing the power grid requesting a change in the power factor of the distributed power sources, the receiving unit receiving response information from the higher-level system permitting a change in the power factor of the distributed power sources, and the control unit, upon receiving the response information, controlling the power factor of the distributed power sources in accordance with the reactive power supplied from the compensation device.

4. The control server according to at least one of claims 1 to 3, wherein the control unit detects a first compensation device which has experienced a communication failure with the control server, and when it detects a second compensation device which has not experienced a communication failure with the control server, it instructs the second compensation device to compensate for the reactive power supplied by the first compensation device.

5. The control unit detects a first compensation device which has experienced a communication failure with the control server, and when it does not detect a second compensation device which has not experienced a communication failure with the control server, it instructs the distributed power supply to determine the power factor of the distributed power supply, according to at least one of claims 1 to 4.

6. A power system comprising: a distributed power source connected to a power grid; a compensation device disposed in the power grid; and a control server that controls the distributed power source and the compensation device, wherein the compensation device is a device that supplies reactive power to the power grid; the control server receives information indicating the voltage of the power grid, controls the reactive power supplied from the compensation device based on the information indicating the voltage of the power grid, and controls the power factor of the distributed power source in accordance with the reactive power supplied from the compensation device.

7. The power system according to claim 6, wherein the distributed power source autonomously applies the power factor of the distributed power source when it detects a communication failure between the distributed power source and the control server.

8. The power system according to claim 6 or 7, wherein the compensation device autonomously contributes the reactive power when the per-unit time fluctuation range of the voltage of the power system monitored by the compensation device exceeds a threshold.

9. The power system according to claim 8, wherein the compensation device transmits information to the control server indicating voltage fluctuations due to an increase in the output power of the distributed power supply.

10. A control method comprising: step A receiving information indicating the voltage of a power system; and step B controlling a distributed power source connected to the power system and a compensation device disposed in the power system, wherein the compensation device is a device that contributes reactive power to the power system, and step B includes the steps of controlling the reactive power contributed from the compensation device based on information indicating the voltage of the power system, and controlling the power factor of the distributed power source in accordance with the reactive power contributed from the compensation device.

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