Power grid supporting type energy storage power station and operation method

Abstract

The invention provides a power grid supporting type energy storage power station and an operation method, the energy storage power station is connected with an external high-voltage alternating current bus, and the energy storage power station comprises a grid-connected energy storage all-in-one machine, an energy storage direct current converter, a low-voltage direct current bus and voltage strength supporting type equipment; the grid-connected energy storage all-in-one machine is connected to the high-voltage AC bus One side of the energy storage DC converter is connected with the grid-connected energy storage all-in-one machine, and the other side is connected with the low-voltage DC bus The voltage intensity supporting type equipment is connected to the low-voltage direct-current bus; during normal operation of the power grid, the grid-connected energy storage all-in-one machine performs power charging and discharging according to a scheduling instruction; during a power grid fault period, low-voltage direct current provided by the grid-connected energy storage all-in-one machine is converted through the voltage intensity supporting type equipment to provide stable voltage support for the high-voltage alternating current bus; the method can be compatible with an existing energy storage power station, the operation mode of an original power station is not affected, and voltage strength support of a power grid can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible AC power transmission and distribution equipment for power grids, and in particular to a power grid-supported energy storage power station and an operation method thereof. Background Art

[0002] Due to the uncertainty of the output of wind and solar power and other renewable energy sources in the power grid system, the voltage strength of the power grid is reduced, and the transmission side of large renewable energy bases presents the characteristics of a weak power grid. The limitation of the short-circuit ratio directly leads to the limitation of the power output of renewable energy, and the renewable energy stations cannot deliver at full power. The installation of synchronous phase regulators can improve the short-circuit ratio of renewable energy grid connection points, but the phase regulators are expensive and have large losses, which brings burdens to the operation and maintenance and economy of renewable energy stations.

[0003] Transforming traditional grid-following energy storage into grid-building energy storage is another way to improve the short-circuit ratio of the grid connection point. The energy storage converter (PCS, Power Conversion System) of the conventional energy storage power station is replaced with high-configuration devices, the PCS is operated at a reduced rating, and the control is changed to grid-building control, so that the energy storage PCS can reach 3 times the rated current output during the transient process of the power grid fault to support the grid voltage. However, most conventional energy storage currently adopts a multi-machine parallel boosting solution at a low voltage level (mostly 690V), which requires multi-stage boosting and parallel connection through transformers. There are multiple machine circulating currents between multiple grid-building PCSs, which can easily lead to oscillations and even transient synchronization instability. It is difficult to achieve ideal support effects under transient conditions.

[0004] In order to avoid the large-scale and massive grid-connected energy storage PCS, some high-voltage direct-mounted cascade energy storage solutions are adopted to integrate the energy storage elements into the DC side of the converter valve submodule, resulting in the energy storage elements being placed at a high potential, which places high requirements on the insulation performance of the energy storage elements. The coupling between the power grid and the energy storage elements will affect the energy storage elements. Therefore, this solution is not suitable for scenarios where large-capacity energy storage is connected to the grid. In addition, the high-voltage direct-mounted cascade energy storage solution is incompatible with existing energy storage power stations. Summary of the invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the present invention proposes a grid-supported energy storage power station, which is connected to an external high-voltage AC bus, and comprises: a grid-connected energy storage integrated machine, an energy storage DC converter, a low-voltage DC bus, and voltage strength support equipment;

[0006] The grid-connected energy storage integrated machine is connected to the high-voltage AC bus; one side of the energy storage DC converter is connected to the grid-connected energy storage integrated machine, and the other side is connected to the low-voltage DC bus; the voltage strength support equipment is connected to the low-voltage DC bus;

[0007] During normal operation of the power grid, the grid-connected energy storage integrated device outputs or absorbs active power according to the dispatching instructions; during a power grid fault, the energy storage DC converter converts the initial low-voltage DC power provided by the grid-connected energy storage integrated device into low-voltage DC power and inputs it into the low-voltage DC bus, and converts the low-voltage DC power output by the low-voltage DC bus into high-voltage AC power through the voltage strength support equipment, outputs reactive power to the high-voltage AC bus, and provides stable grid voltage support.

[0008] Optionally, the grid-connected energy storage integrated machine comprises: a transformer, an energy storage converter and an energy storage element connected in sequence;

[0009] The output DC side of the energy storage element leads out a DC connection line, which is connected to the energy storage DC converter through the lead-out DC connection line; the transformer is connected to the high-voltage AC bus;

[0010] The energy storage inverter inverts the initial low-voltage direct current output by the energy storage element into low-voltage alternating current according to the scheduling instruction, and inputs it into the transformer; the low-voltage alternating current is boosted into high-voltage alternating current by the transformer and input into the high-voltage alternating current bus to maintain the stable operation of the high-voltage alternating current bus.

[0011] Optionally, the voltage strength support equipment includes a controller, the grid-connected energy storage integrated machine includes a corresponding energy management system, and the energy storage power station includes a plurality of grid-connected energy storage integrated machines;

[0012] The controller is respectively connected to the energy management system of each of the grid-connected energy storage integrated machines for communication, so as to realize data exchange between the voltage strength support equipment and each of the grid-connected energy storage integrated machines.

[0013] Optionally, the data exchanged between the voltage strength support equipment and each of the grid-connected energy storage integrated machines is the charge state of the energy storage element in the grid-connected energy storage integrated machine.

[0014] Optionally, the voltage strength support equipment includes: a converter valve, a high-voltage DC bus and an isolated DC converter module connected in sequence;

[0015] One side of the isolated DC converter module is connected to the high-voltage DC bus, and the other side is connected to the low-voltage AC bus; one side of the converter valve is connected to the high-voltage AC grid, and the other side is connected to the high-voltage DC bus;

[0016] The isolated DC converter converts the low-voltage DC power output by the low-voltage DC bus into high-voltage DC power, inputs it into the high-voltage DC bus, and converts the high-voltage DC power output by the high-voltage DC bus into high-voltage AC power through the converter valve, outputs reactive power to the high-voltage AC bus, and provides stable grid voltage support.

[0017] Optionally, the isolated DC converter module includes a plurality of groups of isolated DC converters connected in sequence;

[0018] Each group of the isolated DC converters comprises a high-voltage DC side full-bridge converter, a high-frequency transformer and a low-voltage DC side full-bridge converter connected in sequence;

[0019] The high-voltage DC side full-bridge converters of each group of the isolated DC converters are connected in series, and the lead wires after the series connection are connected to the high-voltage DC bus; the low-voltage DC side full-bridge converters of each group of the isolated DC converters are connected in parallel, and the lead wires after the parallel connection are connected to the low-voltage DC bus;

[0020] The electrical isolation between the low voltage direct current and the high voltage direct current is achieved by the high frequency transformer.

[0021] Optionally, a DC capacitor is provided on the high-voltage DC bus;

[0022] Based on the voltage change of the high-voltage DC bus, the DC capacitor is charged and discharged through the isolated DC converter module to maintain the voltage of the high-voltage DC bus constant.

[0023] Optionally, the voltage strength support equipment further includes a filter module connected between the converter valve and the high-voltage AC bus;

[0024] The filter module includes one of the following: an L filter, an LC filter or an LCL filter.

[0025] Optionally, the converter valve includes one of the following: a two-level converter valve, a three-level converter valve, a multi-level converter valve and an MMC converter valve.

[0026] Optionally, the minimum number and power of energy storage elements required in the energy storage power station are determined according to the minimum required power of the voltage intensity support type equipment;

[0027] The calculation formula for the minimum number and power of energy storage elements required is:

[0028] N×P L-DCDC =N×P battery >P need >(N-1)×P battery

[0029] Among them, P need represents the minimum required power of voltage strength support equipment; N represents the minimum number of energy storage elements required in the energy storage power station, and each energy storage element corresponds to one grid-connected energy storage integrated machine; P battery Represents the power of the energy storage element; P L-DCDCRepresents the power of the energy storage DC converter.

[0030] Based on the same inventive concept, the present invention also proposes an operation method of a grid-supported energy storage power station, comprising:

[0031] During the normal operation of the power grid, the grid-connected energy storage device outputs or absorbs active power based on the control response dispatch command through the grid-following control method;

[0032] During a grid fault, the voltage strength support equipment emits or absorbs reactive power according to the voltage change of the high-voltage AC bus; and the grid-connected energy storage integrated machine outputs active power to the low-voltage DC bus through the energy storage DC converter. The low-voltage DC bus outputs the received active power to the voltage strength support equipment, and outputs reactive power to the high-voltage AC bus through the voltage strength support equipment, providing stable grid voltage support.

[0033] Optionally, the energy storage power station includes multiple grid-connected energy storage integrated machines. During the operation of the power grid, the controller of the voltage strength support equipment exchanges data with the energy management system of each grid-connected energy storage integrated machine to avoid energy storage output conflicts of the grid-connected energy storage integrated machines.

[0034] Optionally, the data exchanged between the controller of the voltage strength support equipment and each of the grid-connected energy storage integrated machines is the charge state of the energy storage element in the grid-connected energy storage integrated machine.

[0035] In another aspect, the present application further provides an electronic device, comprising: at least one processor and a memory; the memory and the processor are connected via a bus;

[0036] The memory is used to store one or more programs;

[0037] When the one or more programs are executed by the at least one processor, an operating method of a grid-supported energy storage power station as described above is implemented.

[0038] On the other hand, the present application also provides a computer-readable storage medium having an execution program stored thereon, and when the execution program is executed, the operation method of a grid-supported energy storage power station as described above is implemented.

[0039] Compared with the closest prior art, the present invention has the following beneficial effects:

[0040] The present invention provides a grid-supported energy storage power station and an operation method, wherein the energy storage power station is connected to an external high-voltage AC bus, and comprises: a grid-connected energy storage integrated machine, an energy storage DC converter, a low-voltage DC bus, and voltage strength support equipment; the grid-connected energy storage integrated machine is connected to the high-voltage AC bus; one side of the energy storage DC converter is connected to the grid-connected energy storage integrated machine, and the other side is connected to the low-voltage DC bus; the voltage strength support equipment is connected to the low-voltage DC bus; during normal operation of the power grid, the grid-connected energy storage integrated machine responds to the dispatched power command; during power grid faults, the voltage strength support equipment converts the low-voltage DC power provided by the grid-connected energy storage integrated machine, continuously outputs reactive power to the high-voltage AC bus, and provides stable power grid voltage support. In the present invention, the initial low-voltage direct current output by the energy storage element in the grid-connected energy storage integrated machine is collected into the low-voltage direct current bus through the energy storage direct current converter, that is, the energy storage element is at a low potential, with high safety performance and low insulation requirements; and during normal operation, the original grid-connected energy storage integrated machine of the energy storage power station is used for response scheduling, which is compatible with the existing energy storage power station and does not affect the original power station operation mode; the decoupling of energy storage and the power grid is achieved through the energy storage direct current converter and the voltage strength support equipment, which is beneficial to the safe operation of the energy storage element. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of the structure of a grid-supported energy storage power station provided by the present invention;

[0042] Figure 2 A schematic diagram of the structure of an energy storage element using an energy storage battery provided by the present invention;

[0043] Figure 3 A schematic diagram of the structure of the bidirectional energy storage DC / DC link provided by the present invention;

[0044] Figure 4 A schematic structural diagram of a three-level converter valve with IGBT series structure provided by the present invention;

[0045] Figure 5 The isolated DC / DC topology structure provided by the present invention;

[0046] Figure 6 A schematic diagram of connecting multiple groups of isolated DC / DCs provided by the present invention;

[0047] Figure 7 A schematic diagram of communication between the voltage support equipment and the energy storage integrated machine provided by the present invention;

[0048] Figure 8 A schematic diagram of a flow chart of an operation method of a grid-supported energy storage power station provided by the present invention;

[0049] Fig. 9The present invention provides a schematic structural diagram of an electronic device. DETAILED DESCRIPTION

[0050] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0051] Example 1

[0052] In addition to the above-mentioned problems, the existing high-voltage direct-mounted cascade energy storage solution is not suitable for adding new energy storage capacity to meet the voltage strength requirements of the existing energy storage power stations. Otherwise, it will increase huge equipment costs and is incompatible with existing energy storage power stations.

[0053] In view of the above problems, this embodiment provides a grid-supported energy storage power station. Without increasing the energy storage capacity of the energy storage power station, a voltage strength support type equipment directly hung on the high-voltage AC bus is added to support the grid voltage during a grid fault. Figure 1 As shown, the energy storage power station is connected to an external high-voltage AC bus, and the energy storage power station includes: a grid-connected energy storage integrated machine, an energy storage DC converter, a low-voltage DC bus, and voltage strength support equipment;

[0054] The grid-connected energy storage integrated machine is connected to the high-voltage AC bus; one side of the energy storage DC converter is connected to the grid-connected energy storage integrated machine, and the other side is connected to the low-voltage DC bus; the voltage strength support equipment is connected to the low-voltage DC bus, and the other side is connected to the high-voltage AC bus;

[0055] During normal operation of the power grid, the grid-connected energy storage integrated device outputs or absorbs active power for charging and discharging according to the dispatching instructions; during a power grid fault, the energy storage DC converter converts the initial low-voltage DC power provided by the grid-connected energy storage integrated device into low-voltage DC power and inputs it into the low-voltage DC bus, and converts the low-voltage DC power output by the low-voltage DC bus into the high-voltage DC power and maintains voltage stability through the isolated DC converter in the voltage strength support equipment, and outputs reactive power to the high-voltage AC bus through the voltage strength support equipment to provide stable power grid voltage support.

[0056] The energy storage power station provided in this embodiment includes a plurality of grid-connected energy storage integrated machines and energy storage DC converters, and each energy storage DC converter is connected to a corresponding grid-connected energy storage integrated machine.

[0057] The grid-connected energy storage integrated machine comprises: a transformer, an energy storage converter (energy storage PCS, Power Conversion System) and an energy storage element connected in sequence; the transformer is connected to the high-voltage AC bus;

[0058] The energy storage element outputs a DC voltage and a DC current, and the low-voltage DC power output by the energy storage element is recorded as the initial low-voltage DC power;

[0059] The energy storage converter is used to invert the initial low-voltage direct current output by the energy storage element into low-voltage alternating current (AC voltage and AC current) according to the dispatching instruction, and input the low-voltage alternating current into the transformer;

[0060] The transformer is used to boost the low-voltage AC power to the high-voltage AC power required by the high-voltage AC bus, and input it into the high-voltage AC bus, that is, boost it to the high-voltage level of the high-voltage AC bus and connect it to the grid; the rated voltage of the low-voltage side of the transformer provided in this embodiment is 0.69KV, and the rated voltage of the high-voltage side is 35KV. During operation, the grid-connected energy storage integrated device outputs or absorbs active power for charging and discharging according to the dispatching instructions to maintain the operation of the power grid.

[0061] Among them, the energy storage element can adopt the conventional energy storage method of energy storage power station, such as Figure 2 As shown, a battery compartment is used which is composed of multiple groups of energy storage lithium batteries connected in series.

[0062] The output DC side of the energy storage element leads to a DC connection line, which is connected to the energy storage DC converter through the lead-out DC connection line. Figure 3 As shown, it is a structural diagram of the energy storage DC converter, which is a bidirectional energy storage DC / DC (bidirectional energy storage DC / DC converter); the two ends of the energy storage DC converter are respectively connected to the DC output of the energy storage element and the low-voltage DC bus.

[0063] The energy storage DC converter is connected to the low-voltage DC bus and is used to convert the initial low-voltage DC power output from the energy storage element into the low-voltage DC power required by the low-voltage DC bus during a power grid failure, and input the low-voltage DC power into the low-voltage DC bus; both sides of the energy storage DC converter are low voltage.

[0064] The DC voltage value of the energy storage element will change with the charging and discharging of the battery, and the low-voltage DC bus needs to be maintained at a fixed value. The energy storage DC converter changes the DC voltage conversion by controlling the duty cycle of its internal switching devices to output the voltage required by the low-voltage DC bus. By changing the initial low-voltage DC output of the energy storage element, a stable low-voltage DC is provided for the low-voltage DC bus to maintain the stability of the low-voltage DC bus.

[0065] When the power grid is operating normally, the energy storage power station can output or absorb active power according to the dispatch instructions; during power grid failure, the energy storage element outputs active power to the low-voltage DC bus through the energy storage DC / DC link in a short period of time to ensure the stability of the low-voltage DC bus voltage.

[0066] Among them, the low-voltage DC bus is used to converge the power output by the energy storage elements in multiple grid-connected energy storage integrated machines. The voltage strength support equipment has certain requirements for power, so the low-voltage DC bus side needs to collect enough energy storage side power. According to the required power requirements, the minimum number and power of energy storage elements required is determined according to the minimum required power of the voltage strength support equipment. The minimum number and power of energy storage elements required can be calculated according to the following formula:

[0067] P DC-bus =N×P L-DCDC =N×P battery >P need >(N-1)×P battery

[0068] Among them, P need Indicates the minimum power required for voltage strength support equipment; N indicates the minimum number of required energy storage elements, each of which corresponds to a grid-connected energy storage integrated machine (each energy storage element here is only a qualitative description, and it does not limit each grid-connected energy storage integrated machine to include only one energy storage element, but is the sum of the energy storage battery clusters therein); P battery Represents the power of each energy storage element; P L-DCDC Represents the power of each energy storage DC converter; P DC-bus It represents the power of the low-voltage DC bus, which is equal to the power of N groups of batteries (N energy storage elements) and also equal to the power of N groups of energy storage DC / DC.

[0069] The voltage strength support equipment includes: a converter valve, a high-voltage DC bus and an isolated DC converter module (isolated DC / DC link) connected in sequence;

[0070] The isolated DC converter module is divided into a high-voltage side and a low-voltage side, one side (the high-voltage side) of which is connected to the high-voltage DC bus, and the other side (the low-voltage side) is connected to the low-voltage DC bus, and is used to convert the low-voltage DC power output by the low-voltage DC bus into high-voltage DC power and input it into the high-voltage DC bus;

[0071] One side of the converter valve is connected to the high-voltage AC power grid, and the other side is connected to the high-voltage DC bus, and is used to invert the high-voltage DC power output by the high-voltage DC bus into high-voltage AC power, and output reactive power to the high-voltage AC bus to provide stable voltage support.

[0072] The converter valve in the voltage strength support equipment adopts DC-AC conversion control. Its main function is to output three-phase AC voltage through inverter control of high-voltage DC voltage and input it into the AC grid (high-voltage AC bus), especially to output or absorb reactive power during grid voltage failure.

[0073] Specifically, the converter valve includes one of the following: a two-level converter valve, a three-level converter valve, a multi-level converter valve and an MMC converter valve. Among them, a converter valve based on an IGBT (Insulated Gate Bipolar Transistor) series structure is preferred. Figure 4 As shown, it is a schematic diagram of a three-level converter valve structure with an IGBT series structure; each phase bridge arm adopts an IGBT device direct series structure, each phase bridge arm is clamped by two groups of diodes, the DC side is connected to the high-voltage DC bus, and the AC side outputs A, B, and C three-phases to the high-voltage AC bus. In this embodiment, the voltage strength support equipment includes a filtering module, so the output A, B, and C three-phase currents are input into the high-voltage AC bus after passing through the filtering module.

[0074] The isolated DC converter module includes a plurality of groups of isolated DC converters connected in sequence;

[0075] like Figure 5 As shown, each group of the isolated DC converters consists of three parts, including a high-voltage DC side full-bridge converter, a high-frequency transformer and a low-voltage DC side full-bridge converter connected in sequence, and the high-frequency transformer is used to achieve electrical isolation between the low-voltage DC power and the high-voltage DC power;

[0076] like Figure 6 As shown, it is a connection diagram between each group of isolated DC converters (isolated DC / DC), the high-voltage DC side full-bridge converters of each group of isolated DC converters are connected in series, and the lead wires at both ends after the series connection are connected to the high-voltage DC bus, and the low-voltage DC side full-bridge converters of each group of the isolated DC converters are connected in parallel, and the lead wires after the parallel connection are connected to the low-voltage DC bus. Through multiple groups of connections, the low-voltage DC power in the low-voltage DC bus is converted into high-voltage DC power and output to the high-voltage DC bus.

[0077] like Figure 1 As shown, a DC capacitor is provided on the high-voltage DC bus to provide a constant DC voltage;

[0078] The DC capacitor is used to charge and discharge itself through the isolated DC converter module based on the voltage change of the high-voltage DC bus, so as to maintain the voltage of the high-voltage DC bus constant.

[0079] Optionally, the voltage strength support equipment further includes a filter module connected between the converter valve and the high-voltage AC bus;

[0080] The filter module includes one of the following: an L filter, an LC filter or an LCL filter. The converter valve is directly connected to the high-voltage AC busbar via the filter module.

[0081] Furthermore, the voltage strength support equipment includes a controller, and each of the grid-connected energy storage integrated devices includes a corresponding energy management system (EMS), such as Figure 7 As shown, the multiple grid-connected energy storage integrated machines include a first energy storage integrated machine, a second energy storage integrated machine, ..., an Nth energy storage integrated machine, and each energy storage integrated machine corresponds to an energy management system EMS;

[0082] The controller of the voltage strength support equipment is communicatively connected to the energy management system of each of the grid-connected energy storage integrated machines. The voltage strength support equipment exchanges data with each of the grid-connected energy storage integrated machines through a communication interface to avoid output conflicts of energy storage elements. The data in the data exchange is the charge state of the battery in the energy storage element.

[0083] In summary, the voltage strength support type equipment included in the grid-supported energy storage power station provided by the present invention can maintain the stable operation of the grid during a grid fault, and is used to improve the voltage strength and system inertia of the grid; and the voltage strength support type equipment is directly connected to the high-voltage AC bus, which can realize the large-capacity design of a single group of support type equipment, avoiding the problems of circulating current and transient oscillation caused by large-scale low-voltage support type equipment after boosting and grid connection, and maintaining the stable operation of the grid;

[0084] Furthermore, the structure proposed by the present invention is a structure integrated with the existing energy storage power station. The existing mature energy storage products (i.e., the grid-connected energy storage integrated machine in the present invention) can continue to be used, and the existing grid-connected energy storage integrated machine connected to the high-voltage AC bus maintains grid-following control and responds to dispatching instructions.

[0085] The structure proposed in the present invention is compatible and can be applied to energy storage power stations that have been put into operation to perform grid-type transformation to achieve stable current output during transient grid faults and support grid voltage without increasing the cost of the original energy storage capacity and affecting the operation and control mode of the original energy storage power station during normal grid operation.

[0086] The present invention also realizes the functional decoupling between the voltage strength support equipment and the grid-connected energy storage integrated machine through a two-stage DC / DC link, specifically, the initial low-voltage DC outputted from the energy storage element is converted into the low-voltage DC required by the low-voltage DC bus through the energy storage DC converter (energy storage DC / DC), and then the low-voltage DC is converted into high-voltage DC through the isolated DC converter module (isolated DC / DC) in the voltage strength support equipment, and then converted into the high-voltage AC required by the high-voltage AC bus through the converter valve to maintain the stability of the power grid. It avoids the problem of coupling between the power grid and the energy storage element caused by the energy storage element in the grid-connected energy storage integrated machine being directly integrated into the DC side of the converter valve, which in turn affects the energy storage element, and is beneficial to the safe operation of the energy storage element; at the same time, the energy storage element is connected to the low-voltage DC bus through the energy storage DC converter, which is at a low potential, and is easy to expand the energy storage capacity, and there is no need to have excessive requirements on the insulation performance of the energy storage element.

[0087] Example 2

[0088] Based on the above-mentioned grid-supported energy storage power station, this embodiment provides an operation method of a grid-supported energy storage power station, such as Figure 8 As shown, including:

[0089] S1. During the normal operation of the power grid, the grid-connected energy storage device outputs or absorbs active power based on the control response dispatch command through the grid-following control method;

[0090] S2. During a grid fault, the voltage strength support equipment emits or absorbs reactive power according to the voltage change of the high-voltage AC bus; and the grid-connected energy storage integrated machine outputs active power to the low-voltage DC bus through the energy storage DC converter; the low-voltage DC bus outputs the received active power to the voltage strength support equipment, and outputs reactive power to the high-voltage AC bus through the voltage strength support equipment, providing stable grid voltage support.

[0091] Specifically, in step S1, during the normal operation of the power grid: the energy storage power station can output or absorb active power according to the original operation mode and control response dispatch instruction, that is, the original grid-connected mode and control of the grid-connected energy storage integrated machine in the existing energy storage power station, which is generally a grid-following control; the energy storage DC converter is used to adjust the initial low-voltage DC power output by the energy storage element to maintain the voltage stability of the low-voltage DC bus, and the isolated DC / DC link in the voltage strength support equipment is used to maintain the voltage stability of the high-voltage DC bus; and then the converter valve is controlled to convert the output reactive current, which is generally a grid-forming control to ensure the voltage stability of the high-voltage AC bus.

[0092] In step S2, during a grid fault, the converter valve of the voltage strength support equipment needs to autonomously respond to the grid fault demand, and emit or absorb reactive power according to the grid voltage change; and the energy storage element in the grid-connected energy storage integrated machine needs to output active power to the low-voltage DC bus and the high-voltage DC bus through a two-stage DC / DC link for a short time during the fault (that is, the active power output by the energy storage element is converted to the low-voltage DC bus through the energy storage DC converter, and the low-voltage DC bus outputs the received active power to the voltage strength support equipment, and converts it to the high-voltage DC bus through the isolated DC / DC link therein) to ensure the voltage stability of the low-voltage DC bus and the high-voltage DC bus, realize reliable output of the converter valve, and maintain the stability of the high-voltage AC bus.

[0093] The energy storage power station provided in this embodiment includes a plurality of the above-mentioned grid-connected energy storage integrated machines.

[0094] The controller of the voltage strength support equipment is connected to the energy management system of each of the grid-connected energy storage integrated machines through communication, and data is exchanged between them to avoid conflicts in energy storage output of the grid-connected energy storage integrated machines.

[0095] The data exchanged between the controller of the voltage strength support equipment and each of the grid-connected energy storage integrated machines is the charge state of the energy storage element in the grid-connected energy storage integrated machine.

[0096] The present application provides an operation method of a grid-supported energy storage power station. During the normal operation of the grid, the existing mature energy storage products (i.e., the grid-connected energy storage integrated machine in the present invention) are used to maintain grid-following control and respond to dispatch instructions, and output power to maintain grid stability during the normal operation of the grid.

[0097] During a grid fault, conventional energy storage elements in the energy storage power station (energy storage elements in the grid-connected energy storage integrated machine) are used to maintain the voltage of the low-voltage DC bus and the high-voltage DC bus respectively through two-stage DC / DC links, and the voltage strength supporting equipment is replenished. This ensures that the converter valve can stably and continuously output reactive current during a grid fault, and can reliably support the grid voltage strength of the energy storage power station and assist in grid fault recovery.

[0098] Example 3

[0099] like Fig. 9As shown, the present invention also provides an electronic device, which may be a computer device, a single-chip device, an intelligent mobile device, etc. The electronic device in this embodiment may include a processor, a memory, a transceiver component, etc. The memory, the processor, and the transceiver component are connected via a bus; the memory may be used to store an execution program, and an exemplary execution program may include instructions; the processor is used to execute the instructions stored in the memory. The memory may also be used to store data, which may be called and / or modified when the instructions are executed.

[0100] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, specifically suitable for loading and executing one or more instructions in a storage medium to implement the corresponding method flow or corresponding functions, so as to implement the steps of the operation method of a grid-supported energy storage power station in the above embodiment.

[0101] Example 4

[0102] Based on the same inventive concept, the present invention also provides a readable storage medium, specifically an electronic device readable storage medium (Memory), which is a memory device in an electronic device for storing programs and data. It can be understood that the storage medium here can include both built-in storage media in electronic devices and, of course, extended storage media supported by electronic devices. The storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by a processor are also stored in the storage space, and these instructions can be one or more execution programs (including program codes). It should be noted that the storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor loads and executes one or more instructions stored in the storage medium, which can implement the steps of the operation method of a grid-supported energy storage power station in the above embodiment.

[0103] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0104] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0105] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0106] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the application, but these changes, modifications or equivalent substitutions are all within the protection scope of the claims to be approved.

Claims

1. A grid-supported energy storage power station, characterized in that: The energy storage power station is connected to an external high-voltage AC bus, and includes: a grid-connected energy storage integrated machine, an energy storage DC converter, a low-voltage DC bus, and voltage strength support equipment; The grid-connected energy storage integrated machine is connected to the high-voltage AC bus; one side of the energy storage DC converter is connected to the grid-connected energy storage integrated machine, and the other side is connected to the low-voltage DC bus; the voltage strength support equipment is connected to the low-voltage DC bus; During normal operation of the power grid, the grid-connected energy storage integrated device outputs or absorbs active power according to the dispatching instructions; during a power grid fault, the energy storage DC converter converts the initial low-voltage DC power provided by the grid-connected energy storage integrated device into low-voltage DC power and inputs it into the low-voltage DC bus, and converts the low-voltage DC power output by the low-voltage DC bus into high-voltage AC power through the voltage strength support equipment, outputs reactive power to the high-voltage AC bus, and provides stable grid voltage support.

2. The energy storage power station according to claim 1, characterized in that: The grid-connected energy storage integrated machine comprises: a transformer, an energy storage converter and an energy storage element connected in sequence; The output DC side of the energy storage element leads out a DC connection line, which is connected to the energy storage DC converter through the lead-out DC connection line; the transformer is connected to the high-voltage AC bus; The energy storage converter is used to invert the initial low-voltage direct current output by the energy storage element into low-voltage alternating current according to the dispatching instruction, and input the low-voltage alternating current into the transformer; the transformer is used to boost the low-voltage alternating current into high-voltage alternating current and input the high-voltage alternating current into the busbar.

3. The energy storage power station according to claim 1, characterized in that: The voltage strength support equipment includes a controller, the grid-connected energy storage integrated machine includes a corresponding energy management system, and the energy storage power station includes a plurality of grid-connected energy storage integrated machines; The controller is respectively connected to the energy management system of each of the grid-connected energy storage integrated machines for communication, so as to realize data exchange between the voltage strength support equipment and each of the grid-connected energy storage integrated machines.

4. The energy storage power station according to claim 3, characterized in that: The data exchanged between the voltage strength support equipment and each of the grid-connected energy storage integrated machines is the charge state of the energy storage element in the grid-connected energy storage integrated machine.

5. The energy storage power station according to claim 1, characterized in that: The voltage strength support equipment includes: a converter valve, a high-voltage DC bus and an isolated DC converter module connected in sequence; One side of the isolated DC converter module is connected to the high-voltage DC bus, and the other side is connected to the low-voltage AC bus; one side of the converter valve is connected to the high-voltage AC grid, and the other side is connected to the high-voltage DC bus; The isolated DC converter converts the low-voltage DC power output by the low-voltage DC bus into high-voltage DC power, inputs it into the high-voltage DC bus, and converts the high-voltage DC power output by the high-voltage DC bus into high-voltage AC power through the converter valve, outputs reactive power to the high-voltage AC bus, and provides stable grid voltage support.

6. The energy storage power station according to claim 5, characterized in that: The isolated DC converter module includes a plurality of groups of isolated DC converters connected in sequence; Each group of the isolated DC converters comprises a high-voltage DC side full-bridge converter, a high-frequency transformer and a low-voltage DC side full-bridge converter connected in sequence; The high-voltage DC side full-bridge converters of each group of the isolated DC converters are connected in series, and the lead wires after the series connection are connected to the high-voltage DC bus; the low-voltage DC side full-bridge converters of each group of the isolated DC converters are connected in parallel, and the lead wires after the parallel connection are connected to the low-voltage DC bus; The electrical isolation between the low voltage direct current and the high voltage direct current is achieved by the high frequency transformer.

7. The energy storage power station according to claim 5, characterized in that: A DC capacitor is provided on the high-voltage DC bus; Based on the voltage change of the high-voltage DC bus, the DC capacitor is charged and discharged through the isolated DC converter module to maintain the voltage of the high-voltage DC bus constant.

8. The energy storage power station according to claim 5, characterized in that: The voltage strength support equipment further includes a filter module connected between the converter valve and the high voltage AC bus; The filter module includes one of the following: an L filter, an LC filter or an LCL filter.

9. The energy storage power station according to claim 5, characterized in that: The converter valve includes one of the following: a two-level converter valve, a three-level converter valve, a multi-level converter valve and an MMC converter valve.

10. The energy storage power station according to claim 2, characterized in that: The minimum number and power of energy storage elements required in the energy storage power station are determined according to the minimum required power of the voltage intensity support type equipment; The calculation formula for the minimum number and power of energy storage elements required is: N×P L-DCDC =N×P battery >P need >(N-1)×P battery Among them, P need represents the minimum required power of voltage strength support equipment; N represents the minimum number of energy storage elements required in the energy storage power station, and each energy storage element corresponds to one grid-connected energy storage integrated machine; P battery Represents the power of the energy storage element; P L-DCDC Represents the power of the energy storage DC converter.

11. A method for operating a grid-supported energy storage power station, characterized in that: include: During the normal operation of the power grid, the grid-connected energy storage device outputs or absorbs active power based on the control response dispatch command through the grid-following control method; During a grid fault, the voltage strength support equipment emits or absorbs reactive power according to the voltage change of the high-voltage AC bus; and the grid-connected energy storage integrated machine outputs active power to the low-voltage DC bus through the energy storage DC converter. The low-voltage DC bus outputs the received active power to the voltage strength support equipment, and outputs reactive power to the high-voltage AC bus through the voltage strength support equipment, providing stable grid voltage support.

12. The method according to claim 11, characterized in that The energy storage power station includes a plurality of the grid-connected energy storage integrated machines. During the operation of the power grid, the controller of the voltage strength support equipment exchanges data with the energy management system of each of the grid-connected energy storage integrated machines to avoid conflicts in energy storage output of the grid-connected energy storage integrated machines.

13. The method according to claim 12, characterized in that The data exchanged between the controller of the voltage strength support equipment and each of the grid-connected energy storage integrated machines is the charge state of the energy storage element in the grid-connected energy storage integrated machine.

14. An electronic device, characterized in that: include: at least one processor and memory; The memory and the processor are connected via a bus; The memory is used to store one or more programs; When the one or more programs are executed by the at least one processor, an operating method of a grid-supported energy storage power station as described in any one of claims 11 to 13 is implemented.

15. A computing device readable storage medium, characterized in that: An execution program is stored thereon, and when the execution program is executed, an operation method of a grid-supported energy storage power station as described in any one of claims 11 to 13 is implemented.

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