A black start control method and system of a power system

Abstract

The application relates to the technical field of energy storage black start, and discloses a black start control method and system for a power system. Each energy storage unit and auxiliary machine load in the power system are connected to the same DC bus; the method comprises the following steps: after the power system enters a black state, controlling a UPS power supply in the power system to supply power to the auxiliary machine load of a first target energy storage unit, so that the first target energy storage unit resumes normal operation; after the first target energy storage unit resumes normal operation, controlling the first target energy storage unit to supply power to the auxiliary machine load of a second target energy storage unit through the DC bus, the second target energy storage unit at least comprising the first target energy storage unit; when black start is needed, controlling the second target energy storage unit to supply power for black start of the power system. The long-time normal operation of the energy storage unit can be maintained, there is always a normally-operating energy storage unit to supply power during black start, the normal black start is ensured, and the black start success rate under the condition of no manual intervention is improved.

Description

Technical Field

[0001] This application relates to the field of energy storage black start technology, and in particular to a black start control method and system for power systems. Background Technology

[0002] Black start refers to a situation where the entire power system is shut down due to a fault, resulting in a complete power outage and a "black state." Without relying on other networks, the system recovers by starting its own generators, which in turn start other generators that lack self-starting capabilities, gradually expanding the recovery range until the entire system is restored. Energy storage power stations (such as wind power storage, photovoltaic energy storage, or grid-connected energy storage stations) are highly suitable as active energy storage devices for use as black start power sources.

[0003] However, when using energy storage power stations as black start power sources, black start failures sometimes occur. Summary of the Invention

[0004] This application provides a black start control method and system for a power system, which can maintain the long-term normal operation of energy storage units, so that when a black start is required, there are always normally operating energy storage units to provide power for the black start in real time, ensuring the normal progress of the black start and improving the success rate of black start without human intervention.

[0005] The first aspect of this application provides a black-start control method for a power system, the power system including multiple energy storage units, and each of the multiple energy storage units and its auxiliary load are connected to the same DC bus; the method includes: after the power system enters a black state, controlling the UPS power supply in the power system to supply power to the auxiliary load of a first target energy storage unit, so that the first target energy storage unit resumes normal operation, the first target energy storage unit being one or more of the multiple energy storage units; after the first target energy storage unit resumes normal operation, controlling the first target energy storage unit to supply power to the auxiliary load of a second target energy storage unit through the DC bus, so that the second target energy storage unit resumes normal operation, the second target energy storage unit including at least the first target energy storage unit; when a black start is required, controlling the second target energy storage unit to supply power for the black start of the power system.

[0006] A second aspect of this application also provides a black-start control system for a power system, comprising: an energy storage system including a plurality of energy storage units, wherein each of the plurality of energy storage units and the auxiliary load of each energy storage unit are connected to the same DC bus; and a control device configured to execute the black-start control method for the power system as described in this application, so as to control the energy storage system to supply power for the black start of the power system.

[0007] The technical solution provided in this application has at least the following advantages: A DC bus is provided to connect to each energy storage unit and the auxiliary load of each energy storage unit, forming a power supply path from each energy storage unit to each other and their auxiliary loads. After the first target energy storage unit is powered by the UPS and its normal operation is restored, the first target energy storage unit can power the second target energy storage unit through the power supply path formed by the DC bus. This allows the second target energy storage unit to maintain normal operation for a long time using the energy of the energy storage unit, instead of stopping directly after all the power of the UPS is released, which would lead to a lack of normally operating energy storage units and black start failure when performing a black start on the power system. Attached Figure Description

[0008] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0009] Figure 1 This is a schematic diagram of a structure of an energy storage power station provided in one embodiment of this application; Figure 2 This is a schematic diagram of a structure of an energy storage system provided in another embodiment of this application; Figure 3 This is a flowchart of a black-start control method for a power system provided in another embodiment of this application; Figure 4 This is another flowchart of a black-start control method for a power system provided in another embodiment of this application; Figure 5 This is another flowchart of a black-start control method for a power system provided in another embodiment of this application. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the various embodiments of this application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been presented in the various embodiments of this application to enable readers to better understand this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0011] The division of the following embodiments is for ease of description and should not constitute any limitation on the specific implementation of this application. The various embodiments can be combined with and referenced by each other without contradiction.

[0012] Energy storage power stations can convert electrical energy into chemical energy and store it in energy storage batteries when the power system has sufficient power. When the power system's power supply is insufficient or needs to be regulated, the chemical energy stored in the energy storage batteries can be converted back into electrical energy to supply the power system. For example, Figure 1 As shown, the structure of an energy storage power station consists of at least a Battery Energy Storage System (BESS) (i.e., Figure 1 The system comprises BESS-1, BESS-2, ..., BESS-X, and an EMS (Energy Management System). All BESSs communicate with the EMS via data control communication and operate under the management of the EMS. Each battery energy storage system consists of a battery rack (a battery rack is formed by multiple battery modules connected in series, and each battery module is composed of multiple cells connected in parallel), a BMS (Battery Management System), and a PCS (Power Conversion System). In addition, the energy storage power station also includes a thermal management system, a PLC (Programmable Logic Controller), and other controllers.

[0013] In energy storage power stations, components such as the BMS (Battery Management System) and thermal management system support the operation of the station but do not directly participate in the charging and discharging process; these are referred to as "auxiliary loads." Although auxiliary loads do not participate in the charging and discharging process, the energy storage station can only operate normally if these auxiliary loads are functioning correctly. Therefore, in a black-start scenario, it is necessary to first supply power to the auxiliary loads in the energy storage station and restore their normal operation before the energy storage unit can resume normal operation.

[0014] Based on this, in some embodiments, such as Figure 1 As shown, an additional UPS power supply is also provided in the energy storage power station. When the power system enters a black state, the UPS power supply is used to supply power to the auxiliary load of the energy storage power station to restore and maintain the normal operation of the energy storage power station. Thus, when a black start is required, the energy storage power station in normal operation can be used as a black start power supply to support the black start of the power system.

[0015] However, UPS power supplies have limited power and cannot supply power to the energy storage station and its auxiliary loads for a long time. If the black start is triggered only after the UPS power supply has run out of power, the power system will lose the black start power supply because the energy storage unit cannot work properly (i.e. cannot discharge normally), ultimately leading to black start failure.

[0016] To address the aforementioned issues, this application provides a black-start control method for power systems, applied to a control device. This control device can be a controller, an electronic device with control functions, or a power system control system. Based on providing DC buses connected to each energy storage unit and its auxiliary loads, forming a power supply path from each energy storage unit to its auxiliary loads, and after using a UPS to power some energy storage units and their auxiliary loads to restore normal operation of some units, the restored normal-operational energy storage units supply power to the remaining units and their auxiliary loads, thus maintaining the long-term normal operation of the energy storage units. This ensures that when a black start is needed, there are always normally operating energy storage units providing power in real time, guaranteeing the normal progress of the black start and improving the success rate of black starts without human intervention.

[0017] A single energy storage unit can be a rack, or it can be a bank composed of multiple racks. Taking a bank as an example, for instance... Figure 2 As shown, a Bank 101 contains multiple Racks 102, and each Bank 101 has a DC bus 103. Each Rack 102 in a Bank 101 is connected in parallel to the DC bus 103. The DC bus 103 is connected to the high-voltage bus 106 via a PCS 104 and a transformer 105, ultimately connecting to the power grid. Furthermore, a DC bus 107 is provided, which is connected to the DC bus 103 in each Bank 101 and also to the auxiliary loads 108 in each Bank 101. Thus, the DC bus 107 provides a path from any Bank 101 to all other Banks 101 and their auxiliary loads 108, allowing the transmission of electrical energy from any one or more Banks 101 to these loads, maintaining the normal operation of the Banks 101 and their auxiliary loads. Ultimately, by integrating the black-start control method with the corresponding power system, the energy storage unit is maintained in normal operation for a long period of time. This ensures that when a black start is needed, there is always a normally operating energy storage unit providing power for the black start in real time, guaranteeing the normal progress of the black start and improving the success rate of black starts without human intervention.

[0018] Furthermore, in some embodiments, when the state of the electrical energy output by the energy storage unit cannot directly power the auxiliary load, such as... Figure 2 As shown, a converter 109 can also be installed in the energy storage unit (Bank 101) between the auxiliary load 108 and the DC bus 107. Of course, Figure 2For illustrative purposes only, in some embodiments, a converter or similar device may also be installed between the energy storage unit and the DC bus.

[0019] certainly, Figure 2 This is merely an example where each energy storage unit and its auxiliary load are connected to the same DC bus. In some embodiments, however, it is still... Figure 2 The Bank shown is an example of an energy storage unit. The DC bus connecting each energy storage unit and the auxiliary load of each energy storage unit can also be directly connected to at least part of the rack in each Bank and the auxiliary load of each Bank, without needing to be connected through DC bus 1, etc., which will not be listed here.

[0020] The following mainly combines Figures 3-5 The flowchart shown illustrates the black-start control method for power systems.

[0021] In some embodiments, the flow of the black-start control method for a power system is as follows: Figure 3 As shown, it includes at least the following steps: Step S11: After the power system enters a blackout state, control the UPS power supply in the power system to supply power to the auxiliary load of the first target energy storage unit so that the first target energy storage unit can resume normal operation. The first target energy storage unit is one or more energy storage units among multiple energy storage units.

[0022] Step S12: After the first target energy storage unit resumes normal operation, control the first target energy storage unit to supply power to the auxiliary load of the second target energy storage unit through the DC bus, so that the second target energy storage unit can operate normally. The second target energy storage unit includes at least the first target energy storage unit.

[0023] Step S13: When a black start is required, control the second target energy storage unit to supply power for the black start of the power system.

[0024] Thus, a DC bus connecting each energy storage unit and its auxiliary load is provided, forming a power supply path from each energy storage unit to its auxiliary loads. After the UPS power supply powers the first target energy storage unit and restores its normal operation, the first target energy storage unit can power the second target energy storage unit through the power supply path formed by the DC bus. This allows the second target energy storage unit to maintain normal operation for a long time using the energy of the energy storage unit, instead of stopping directly after all the power of the UPS power supply is released, which would lead to a lack of normally operating energy storage units during a black start of the power system and result in a black start failure.

[0025] In step S11, the UPS power supply in the power system can be as follows: Figure 1 The following are different energy storage units ( Figure 1 As shown in the diagram (Rack-1, Rack-2, etc.), an externally deployed UPS power supply shared by different energy storage units can deliver power to the first target energy storage unit under control; alternatively, it can be as follows: Figure 2 As shown in each energy storage unit ( Figure 2 An independent UPS power supply (marked "UPS" in the diagram) is installed within the bank shown. Under control, the UPS power supply in the first target energy storage unit is activated and supplies power to the auxiliary loads of that unit. Of course, the above is only an example of how a UPS power supply powers the auxiliary loads of the first target energy storage unit. In some embodiments, the UPS power supply can also adopt other deployment methods and corresponding approaches to power the auxiliary loads of the first target energy storage unit; these will not be listed here. Through the above method, power is supplied to the auxiliary loads of the first target energy storage unit after a power system failure, thereby restoring the normal operation of the auxiliary loads. Therefore, the first target energy storage unit can resume normal operation based on the normally functioning auxiliary loads.

[0026] It should be noted that this application does not limit the number of energy storage units included in the first target energy storage unit; it can be 1, 2, 4, 7, etc.

[0027] It should also be noted that this application does not limit the method of determining the first target energy storage unit. It can be selected according to a preset strategy or randomly, etc.

[0028] In some embodiments, the first target energy storage unit is determined as follows: at least one energy storage unit is selected from a plurality of energy storage units whose electrical parameters reach a preset threshold as the first target energy storage unit. By selecting an energy storage unit whose electrical parameters reach the preset threshold as the first target energy storage unit, the first target energy storage unit can continuously transmit power through the DC bus for at least the desired period of time. This facilitates the first target energy storage unit maintaining power transmission through the DC bus for a longer period, thereby ensuring the long-term normal operation of the second target energy storage unit, reducing the risk of black start failure, and improving the black start success rate.

[0029] It should be noted that this application does not limit the power parameters; they can be any parameter that can characterize the duration of continuous power supply of the energy storage unit. For example, the power parameters can be the SoC (State of Charge) parameters of the energy storage unit. Alternatively, the power parameters can be determined by the following expression: ;in, Indicates the first The electrical energy parameters of each energy storage unit This indicates the discharge efficiency of the energy storage unit. Indicates the first SoC parameter values ​​for each energy storage unit Indicates the first The rated power of each energy storage unit Indicates the preset first The electrical energy that each energy storage unit needs to retain. This represents the critical load power of the power system's substations. Of course, the above are merely examples of electrical energy parameters. In some embodiments, other parameters can be used as electrical energy parameters, or other calculation methods can be used to calculate electrical energy parameters; these will not be listed here.

[0030] It should also be noted that this application does not limit the first preset threshold, which is related to the meaning of the power parameters, and its specific value can be flexibly configured according to the application scenario, the user's expected power supply duration of the energy storage unit, etc.

[0031] In step S12, after the first target energy storage unit resumes normal operation, it will be able to discharge normally to the outside. At this time, the first target energy storage unit will transmit electrical energy to the connected DC bus, so that electrical energy can be transmitted along the DC bus to any one or more energy storage units, thereby powering the auxiliary load of the second target energy storage unit and enabling the second target energy storage unit to operate normally. The second target energy storage unit includes the first target energy storage unit; that is, the first target energy storage unit can use its own electrical energy to replace the UPS power supply to power its internal auxiliary load, so that the first target energy storage unit is not limited by the UPS power supply and can maintain normal operation for a long time, thus maintaining power supply to the second target energy storage unit for an extended period.

[0032] It should be noted that this application does not limit the second target energy storage unit. It may include only the first target energy storage unit, thereby reducing the power supply pressure on the first target energy storage unit and maintaining the normal operation of the energy storage unit for a longer period of time. This further reduces the risk of black start failure due to the lack of normally operating energy storage units and improves the black start success rate without human intervention. Alternatively, it may include the first target energy storage unit and other energy storage units. For example, the second target energy storage unit may be all energy storage units in the power system. By maintaining the normal operation of other energy storage units, the energy storage units that are maintaining normal operation during black start can provide more power to support black start, thereby further reducing the risk of black start failure due to insufficient power and improving the black start success rate without human intervention.

[0033] It should also be noted that when the first target energy storage unit is used as a power supply, the UPS power supply can be completely off, or it can provide low-voltage power to the auxiliary load through bypass power supply.

[0034] In step S13, the second target energy storage unit can maintain normal operation through the power supply of the first target energy storage unit. Therefore, when a black start is required, some or all of the energy storage units that are maintaining normal operation will be selected as power sources to supply power for the black start of the power system.

[0035] In some embodiments, the flow of the black-start control method for a power system is as follows: Figure 4 As shown, it includes at least the following steps: Step S21: Based on the electrical signal on the high-voltage busbar of the power system connected to the energy storage unit, and the available power of the UPS power supply of the power system, detect whether the power system has entered a black state.

[0036] Step S22: After determining that the power system has entered a black state, control the UPS power supply in the power system to supply power to the auxiliary load of the first target energy storage unit so that the first target energy storage unit can resume normal operation. The first target energy storage unit is one or more energy storage units among multiple energy storage units.

[0037] Step S23: After the first target energy storage unit resumes normal operation, control the first target energy storage unit to supply power to the auxiliary load of the second target energy storage unit through the DC bus, so that the second target energy storage unit can operate normally. The second target energy storage unit includes at least the first target energy storage unit.

[0038] Step S24: When a black start is required, control the second target energy storage unit to supply power for the black start of the power system.

[0039] Therefore, based on other embodiments, by further monitoring the electrical signals on the high-voltage bus of the power system and the available power of the UPS, it can be determined whether to perform subsequent power supply control steps. Under the condition that it is supported, the black state can be detected in time and the corresponding processing can be triggered to maintain the normal operation of the second target energy storage unit for a long time, instead of stopping operation directly after all the power of the UPS is released, which would lead to the lack of a normally operating energy storage unit when performing a black start on the power system, resulting in black start failure.

[0040] It is not difficult to find Figure 4 Steps S22 to S24 shown are Figure 3 Steps S11 to S13 are largely the same, so they will not be repeated here.

[0041] In step S21, the electrical signal on the high-voltage bus of the power system connected to the energy storage unit can detect whether the power system has entered a black state, thereby automatically detecting the power system failure and promptly triggering the subsequent restoration of the normal operation of the second target energy storage unit, preparing power for black start. The available power of the power system's UPS can be used to detect whether the UPS power supply is sufficient to support the restoration of at least some of the auxiliary loads of the energy storage units to normal operation, avoiding resource waste and unnecessary procedures caused by insufficient UPS power leading to the failure of some energy storage units to resume normal operation, thus saving resources. Therefore, the judgment of the power system entering a black state at this time is not only a judgment of power system failure, but also includes a judgment of whether the UPS power supply is available to support the restoration of the energy storage units as a black start power source.

[0042] certainly, Figure 4 For illustrative purposes only, in some embodiments, it may be necessary to determine only whether the power system has lost power, etc., which will not be listed here.

[0043] In some embodiments, the flow of the black-start control method for a power system is as follows: Figure 5 As shown, it includes at least the following steps: Step S31: After determining that the power system has entered a black state, control the UPS power supply in the power system to supply power to the auxiliary load of the first target energy storage unit so that the first target energy storage unit can resume normal operation. The first target energy storage unit is one or more energy storage units among multiple energy storage units.

[0044] Step S32: After the first target energy storage unit resumes normal operation, control the first target energy storage unit to supply power to the auxiliary load of the second target energy storage unit through the DC bus, so that the second target energy storage unit can operate normally. The second target energy storage unit includes at least the first target energy storage unit.

[0045] Step S33: When the first target energy storage unit reaches the preset state, control other energy storage units among the multiple energy storage units to become the new first target energy storage unit, and supply power to the auxiliary load of the second target energy storage unit through the DC bus.

[0046] Step S34: When a black start is required, control the second target energy storage unit to supply power for the black start of the power system.

[0047] Therefore, based on other embodiments, by further switching the first target energy storage unit as the power supply in the black state, the second target energy storage unit can use the power of the energy storage unit to maintain normal operation for a longer period of time, which further reduces the risk of black start failure due to the lack of a normally operating energy storage unit as the black start power supply during black start, and further improves the black start success rate without human intervention.

[0048] It is not difficult to find Figure 5 Steps S31-32 and S34 shown are Figure 3 Steps S11 to S13 are largely the same, so they will not be repeated here.

[0049] In step S33, if the second target energy storage unit only includes the first target energy storage unit, the new first target energy storage unit needs to be an energy storage unit other than the second target energy storage unit; if the second target energy storage unit includes the first target energy storage unit and other energy storage units, the new first target energy storage unit can be an energy storage unit that is not the first target energy storage unit in the second target energy storage unit, or it can be an energy storage unit other than the second target energy storage unit (assuming that the power system has other energy storage units other than the second target energy storage unit), etc.

[0050] It should be noted that this application does not limit the method of determining other energy storage units as the new first target energy storage unit. It can be determined in a similar way to the aforementioned first target energy storage unit, that is, by selecting an energy storage unit as the new first target energy storage unit from other energy storage units whose electrical parameters reach the second preset threshold from multiple energy storage units. Power is supplied to the auxiliary load of the second target energy storage unit through the DC bus. The electrical parameters have been described previously, and the second preset threshold is roughly the same as the aforementioned first preset threshold, so it will not be repeated here.

[0051] For ease of understanding, the determination and use of the new first target energy storage unit will be explained below with reference to different embodiments.

[0052] In some embodiments, controlling other energy storage units among multiple energy storage units as new first target energy storage units to supply power to the auxiliary load of the second target energy storage unit via a DC bus can be achieved as follows: controlling energy storage units that are not the first target energy storage units among the second target energy storage units as new first target energy storage units to supply power to the auxiliary load of the second target energy storage unit via a DC bus. Thus, by determining new first target energy storage units to be used as power sources from the second target energy storage units that are already operating normally, the switching of the first target energy storage unit can be performed without waiting, without needing to restore the normal operation of the new first target energy storage unit.

[0053] In some embodiments, the second target energy storage unit is a portion of multiple energy storage units. Controlling other energy storage units among the multiple energy storage units as new first target energy storage units, and supplying power to the auxiliary loads of the second target energy storage unit through a DC bus, can be achieved in the following ways: controlling the first target energy storage unit to supply power to the second target energy storage unit and the auxiliary loads of other energy storage units among the multiple energy storage units through a DC bus, so that the other energy storage units among the multiple energy storage units resume normal operation and the second target energy storage unit maintains normal operation; controlling other energy storage units among the multiple energy storage units as new first target energy storage units, and supplying power to the auxiliary loads of the new second target energy storage unit composed of the other energy storage units among the multiple energy storage units through a DC bus. By first restoring the normal operation of the new first target energy storage unit when selecting an energy storage unit that has not yet resumed normal operation as the new first target energy storage unit, and then switching the first target energy storage unit used as the power source, the system ensures that the new first target energy storage unit can be used as the power source immediately after the switch, without interruption of the normal operation of the energy storage unit. This further reduces the risk of black start failure and improves the success rate of black start without human intervention.

[0054] It should be noted that the above are just examples. In some embodiments, a UPS power supply can also be used as the power supply for the new first target energy storage unit to resume normal operation. That is, each determined first target energy storage unit is powered by a UPS power supply, thereby reducing the complexity of power supply control, reducing the risk of failure, improving safety, further reducing the risk of black start failure, and improving the success rate of black start without human intervention, etc., which will not be listed here.

[0055] It should also be noted that the aforementioned new first target energy storage unit can be used to replace some of the energy storage units of the original first target energy storage unit. In this case, when there are energy storage units in the first target energy storage unit that reach a preset state, the energy storage units that reach the preset state are the energy storage units that need to be replaced. This fully considers the different power states of different energy storage units in the first target energy storage unit, and can promptly replace the energy storage units in the first target energy storage unit that can no longer supply power while utilizing the power of each energy storage unit in the first target energy storage unit, so as to maintain the normal operation of the energy storage unit for a longer period of time and further improve the success of black start. The aforementioned new first target energy storage unit can also be used to replace all the energy storage units of the original first target energy storage unit. In this case, when there are energy storage units in the first target energy storage unit that reach a preset state, the energy storage units included in the first target energy storage unit are the energy storage units that need to be replaced, thereby improving the replacement efficiency of the energy storage units used as power sources and reducing the complexity of control. Of course, whether it is replacing some or all of the original first target energy storage units, a new second target energy storage unit will be formed based on the new first target energy storage unit. The new second target energy storage unit will include the new first target energy storage unit, but will not include the energy storage units that were replaced.

[0056] Furthermore, this application does not limit the preset state, which can be set according to application scenarios, user needs, etc. For example, the electrical energy of the energy storage battery in the preset state satisfies the following expression: ;in, This refers to the electrical energy of the energy storage battery under preset conditions. This is the sum of the excitation energy and closing energy of the transformer (the transformer through which the energy storage unit connects to the power system). This is the estimated consumption during the pressure build-up phase. These are the first batch of critical loads. This represents the preset energy margin. At this point, the energy storage battery, having reached the preset state, will retain at least enough energy to support a black start, meeting the energy reserve requirements. Therefore, when a black start is needed, there is always sufficient energy to support it, without requiring external power for the black start, further improving the success rate of black starts without human intervention.

[0057] For ease of understanding Figure 5 The process shown below will be explained with specific examples.

[0058] In some examples, assuming the power system has energy storage unit 1, energy storage unit 2, energy storage unit 3, ..., energy storage unit 50, after a black start, the energy storage units 1, 2, 3, ..., 50 are sorted according to their electrical energy parameters. The three energy storage units with the highest electrical energy parameters are selected as the first target energy storage units (let's say energy storage unit 1, 2, and 3). Then, the UPS power supplies in energy storage units 1, 2, and 3 are activated to power the energy storage units 1, 2, and 50. The auxiliary load of Unit 3 is powered to restore the normal operation of Energy Storage Unit 1, Energy Storage Unit 2 and Energy Storage Unit 3. After the normal operation is restored, Energy Storage Unit 1, Energy Storage Unit 2 and Energy Storage Unit 3 transmit electrical energy to the DC bus. The auxiliary loads of Energy Storage Unit 1, Energy Storage Unit 2, Energy Storage Unit 3, ..., Energy Storage Unit 50 (i.e., the second target energy storage unit includes all energy storage units) all obtain electrical energy through the DC bus to restore normal operation. Thus, Energy Storage Unit 1, Energy Storage Unit 2, Energy Storage Unit 3, ..., Energy Storage Unit 50 all resume normal operation. However, as time progresses, energy storage unit 2 reaches its preset state first. Then, following the previous order of energy storage units 4, ..., 50 (or, the electrical parameters of energy storage units 4, ..., 50 can be redefined and reordered to account for changes in electrical energy over time, allowing for more precise selection), the energy storage unit with the highest electrical parameters (let's assume it's energy storage unit 10) is selected to replace energy storage unit 2 in supplying energy to the DC bus, and energy storage unit 2 stops supplying energy to the DC bus. Next, energy storage unit 1 reaches its preset state, and so on... The energy storage units 4, ..., 9, 11, ..., 50 are ordered to select the energy storage unit with the highest electrical parameters to replace energy storage unit 1 in supplying electrical energy to the DC bus. At the same time, energy storage unit 1 stops supplying electrical energy to the DC bus. This process continues until a black start command is received. Then, the currently operating energy storage units are used to supply electrical energy to the power system as black start power sources. After the black start is completed, energy storage units 1, 2, 3, ..., 50 can use the electrical energy of the power system to maintain normal operation without needing to supply power themselves.

[0059] In some examples, assuming the power system has energy storage unit 1, energy storage unit 2, energy storage unit 3, ..., energy storage unit 50, after the power system black start, energy storage units 1, 2, 3, ..., 50 are sorted according to their electrical energy parameters. The five energy storage units with the highest electrical energy parameters are selected as the second target energy storage units, and the three energy storage units with the worst electrical energy parameters among the five highest-performing units are selected as the first target energy storage units (for example, energy storage units 1, 2, and 3 are the first target energy storage units, and energy storage units 1, 2, 3, 4, and 50 are the second target energy storage units). The system first activates the UPS power supplies in energy storage units 1, 2, and 3 to power the auxiliary loads of these units, restoring their normal operation. After normal operation is restored, energy storage units 1, 2, and 3 supply power to the DC bus. The auxiliary loads of energy storage units 1, 2, 3, 49, and 50 all obtain power from the DC bus to restore normal operation, thus restoring normal operation of energy storage units 1, 2, 3, 49, and 50. However, as time progresses, energy storage unit 2 reaches the preset state first. Then, following the previous order of energy storage units 4, ..., 48 (or, the power parameters of energy storage units 4, ..., 48 can be redefined and reordered to account for power changes over time and achieve more precise energy storage unit selection), the three energy storage units with the highest power parameters (let's assume energy storage unit 10, energy storage unit 4, and energy storage unit 5) are selected to replace energy storage units 1, 2, and 3 in supplying power to the DC bus. Simultaneously, energy storage units 1, 2, and 3 cease supplying power to the DC bus. Then, energy storage unit 10 reaches the preset state again. In the current state, following the previous order of energy storage units 6, ..., 9, 11, ..., 48, the energy storage unit with the highest electrical parameters is selected to replace energy storage units 10, 4, and 5 in supplying electrical energy to the DC bus. At the same time, energy storage units 10, 4, and 5 stop supplying electrical energy to the DC bus, and so on, until a black start command is received. Then, the currently operating energy storage units are used to supply electrical energy to the power system as black start power sources. After the black start is completed, energy storage units 1, 2, 3, ..., 50 can use the electrical energy of the power system to maintain normal operation without needing to supply power themselves.

[0060] Therefore, the black start control method for power systems provided in this application can provide a voltage source within milliseconds of the UPS power supply when the busbar loses voltage and the entire substation does not need to perform a black start temporarily. This allows the UPS power supply to provide power to the auxiliary loads of some energy storage units, restoring the normal operation of some energy storage units. Then, the restored energy storage units can statically take over the UPS power supply to provide power to the auxiliary loads of the corresponding energy storage units. This ensures that the energy storage units can maintain black start standby operation for a long time without human intervention. This avoids the problem that when only UPS power is used, it can only provide a few hours of standby time, which leads to UPS power shortage when black start is needed. If no human is available to replace the UPS power supply on-site using a power vehicle or mobile power supply, the black start will fail. This improves the success rate of black start without human intervention.

[0061] The steps of the various methods described above are only for clarity. In practice, they can be combined into one step or some steps can be split into multiple steps. As long as they include the same logical relationship, they are all within the scope of protection of this application. Adding insignificant modifications or introducing insignificant designs to the algorithm or process, but without changing the core design of the algorithm and process, are also within the scope of protection of this application.

[0062] Correspondingly, this application also provides a black-start control system for a power system, including: An energy storage system comprises multiple energy storage units, and each energy storage unit and its auxiliary load are connected to the same DC bus.

[0063] The control device is configured to execute the black-start control method for the power system as described in any of the above embodiments, so as to control the energy storage system to supply power for the black start of the power system.

[0064] The energy storage system provided in this application can Figure 2 As shown. Of course, Figure 2 This is just an example; energy storage systems can also be implemented in other ways, as described earlier, and will not be listed here.

[0065] It is not difficult to see that this embodiment is a system embodiment corresponding to the method embodiment, and this embodiment can be implemented in conjunction with the method embodiment. The relevant technical details mentioned in the method embodiment are still valid in this embodiment, and will not be repeated here to reduce repetition. Correspondingly, the relevant technical details mentioned in this embodiment can also be applied to the method embodiment.

[0066] Furthermore, in order to highlight the innovative aspects of this application, no units that are not closely related to solving the technical problems proposed in this application are introduced in this embodiment, but this does not mean that there are no other units in this embodiment.

[0067] Those skilled in the art will understand that the above embodiments are specific embodiments for implementing this application, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of this application.

Claims

1. A black-start control method for a power system, characterized in that, The power system includes multiple energy storage units, and each energy storage unit and its auxiliary load are connected to the same DC bus; the method includes: After the power system enters a blackout state, the UPS power supply in the power system is controlled to supply power to the auxiliary load of the first target energy storage unit so that the first target energy storage unit can resume normal operation. The first target energy storage unit is one or more of the plurality of energy storage units. After the first target energy storage unit resumes normal operation, the first target energy storage unit is controlled to supply power to the auxiliary load of the second target energy storage unit through the DC bus, so that the second target energy storage unit can operate normally. The second target energy storage unit includes at least the first target energy storage unit. When a black start is required, the second target energy storage unit is controlled to supply power for the black start of the power system.

2. The method according to claim 1, characterized in that, After controlling the first target energy storage unit to supply power to the auxiliary load of the second target energy storage unit through the DC bus, the method further includes: When the first target energy storage unit reaches a preset state, other energy storage units among the plurality of energy storage units are controlled to become the new first target energy storage unit, and the auxiliary load of the second target energy storage unit is powered through the DC bus.

3. The method according to claim 2, characterized in that, The step of controlling other energy storage units among the plurality of energy storage units as new first target energy storage units, and supplying power to the auxiliary load of the second target energy storage unit through the DC bus, includes: The energy storage unit that is not the first target energy storage unit in the second target energy storage unit is controlled as the new first target energy storage unit, and the auxiliary load of the second target energy storage unit is powered through the DC bus.

4. The method according to claim 3, characterized in that, The second target energy storage unit is the plurality of energy storage units.

5. The method according to claim 2, characterized in that, The second target energy storage unit is a portion of the plurality of energy storage units; The step of controlling other energy storage units among the plurality of energy storage units as new first target energy storage units, and supplying power to the auxiliary load of the second target energy storage unit through the DC bus, includes: The first target energy storage unit is controlled to supply power to the auxiliary loads of the second target energy storage unit and other energy storage units among the plurality of energy storage units through the DC bus, so that the other energy storage units among the plurality of energy storage units can resume normal operation and the second target energy storage unit can maintain normal operation. The other energy storage units among the plurality of energy storage units are controlled as new first target energy storage units, and the auxiliary load of the new second target energy storage unit composed of the other energy storage units among the plurality of energy storage units is powered through the DC bus.

6. The method according to any one of claims 2 to 5, characterized in that, The electrical energy of the energy storage battery that reaches the preset state satisfies the following expression: ； in, The energy stored in the battery under the preset state is electrical energy. It is the sum of the transformer's excitation energy and closing energy. This is the estimated consumption during the pressure build-up phase. These are the first batch of critical loads. This is the preset electrical energy margin.

7. The method according to any one of claims 2 to 5, characterized in that, The first target energy storage unit is determined in the following manner: From the plurality of energy storage units, at least one energy storage unit is selected as the first target energy storage unit if the energy parameters of the energy storage units reach the first preset threshold. And / or, The other energy storage units that serve as the new first target energy storage unit are determined in the following manner: Select an energy storage unit from among the multiple energy storage units whose electrical parameters reach the second preset threshold as the new first target energy storage unit, and supply power to the auxiliary load of the second target energy storage unit through the DC bus.

8. The method according to claim 7, characterized in that, The electrical energy parameters are determined by the following expression: ； in, Indicates the first The electrical energy parameters of each energy storage unit, This indicates the discharge efficiency of the energy storage unit. Indicates the first SoC parameter values ​​for each energy storage unit Indicates the first The rated power of each energy storage unit Indicates the preset first The electrical energy that each energy storage unit needs to retain. This indicates the station critical load power of the power system.

9. The method according to any one of claims 1 to 5, characterized in that, Before the UPS power supply controlling the power system supplies power to the first target energy storage unit, the method further includes: Based on the electrical signal on the high-voltage bus of the power system connected to the energy storage unit, and the available power of the UPS power supply of the power system, it is detected whether the power system has entered a blackout state.

10. A black-start control system for a power system, characterized in that, include: An energy storage system comprising multiple energy storage units, wherein each energy storage unit and its auxiliary load are connected to the same DC bus. The control device is configured to perform the black-start control method for a power system as described in any one of claims 1 to 9, to control the energy storage system to supply power for the black start of the power system.

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