Source-load integrated test device and method for grid-related test of energy storage system

Abstract

The invention belongs to the field of function test of an energy storage system, and discloses a source-load integrated test device and method for a grid-related test of the energy storage system, and the device achieves the flexible switching between a voltage source mode and an electronic load mode through the integration of an electric energy conversion unit, an isolation transformer, a high-voltage switch and a control unit. In a voltage source mode, the device can be used as a power grid simulation source with adjustable amplitude, frequency and phase, and the requirements of grid-related tests of an energy storage power station and an energy storage converter are effectively met; in an electronic load mode, the RLC load can be used as an active power and reactive power adjustable RLC load, and is suitable for anti-islanding tests; by adopting the device, the complexity and high cost caused by renting a high-power mobile adjustable RLC load or utilizing another group of energy storage subsystems as the adjustable load in the traditional method are effectively avoided, the detection time period is remarkably shortened, the detection cost is reduced, and the device has higher control precision, so that the detection efficiency is improved. And the accuracy and reliability of the test can be effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical energy storage system testing, specifically to the field of energy storage system function testing, and in particular to a source-load integrated testing device and method for grid-related testing of energy storage systems. Background Art

[0002] At present, new energy storage represented by lithium-ion batteries continues to develop rapidly, with the cumulative installed capacity exceeding 10GW for the first time, reaching 13.1GW / 27.1GWh, with an annual growth rate of 128% in power scale and 141% in energy scale. As electrochemical energy storage systems are continuously connected to the grid, the impact on the power grid has increased dramatically. In order to ensure the orderly flow and safe operation of the power grid, grid connection detection of electrochemical energy storage systems is imperative.

[0003] The grid-connected test items and technical regulations for electrochemical energy storage systems are based on GB / T 36547-2018 "Technical Regulations for Electrochemical Energy Storage Systems Connected to the Grid" and GB / T 36548-2018 "Test Specifications for Electrochemical Energy Storage Systems Connected to the Grid". The two standards specify the technical requirements, test items and methods for the grid-connected test of electrochemical energy storage systems. The unplanned islanding protection function test is an important test item for the grid-connected test of electrochemical energy storage systems. The test results can demonstrate whether electrochemical energy storage can quickly disconnect the circuit breaker connected to the main grid when the grid has high voltage, low voltage, high frequency, low frequency and other faults, to prevent the electrochemical energy storage from matching the load of the user station, forming a small system for self-generation and self-use, and derailing from the main grid. According to the requirements of GB / T36548-2018, the unplanned islanding protection function test of the electrochemical energy storage system requires the coordination of power supply and adjustable RLC load. The existing detection method of the unplanned island protection function of the electrochemical energy storage system requires the coordination of an adjustable RLC load. Since there is no adjustable RLC load in the large-scale electrochemical energy storage system (power station), it is necessary to rent a high-power mobile adjustable RLC load to the site for the test or use another set of energy storage subsystems as an adjustable load. At present, conventional adjustable RLC loads on the market are all gear adjustment, with a control accuracy of about ±2%; therefore, the use of existing detection test methods leads to disadvantages such as long detection time cycle, high detection cost, and poor control accuracy.

[0004] It can be seen that the existing detection test methods require renting a high-power mobile adjustable RLC load to the site for testing or using another set of energy storage subsystems as adjustable loads, which leads to a long detection period, high detection cost and poor control accuracy. Summary of the invention

[0005] The present invention provides a source-load integrated test device and method for grid-related tests of energy storage systems, so as to solve the technical problems of existing detection test methods, such as the need to rent a high-power mobile adjustable RLC load to cooperate with the test on site or use another group of energy storage subsystems as an adjustable load, resulting in a long detection period, high detection cost and poor control accuracy.

[0006] In order to achieve the above object, the present invention adopts the following technical contents: A source-load integrated test device for grid-related tests of energy storage systems, comprising a source-load switching circuit and a control unit; the source-load switching circuit comprises two parallel branches, wherein one branch is provided with: An electric energy conversion unit, used to realize the conversion of AC power from the grid end to AC power from the load end; A first isolation transformer and a second isolation transformer are respectively connected to two sides of the power conversion unit; a first high-voltage switch connected to the first isolation transformer, and a second high-voltage switch connected to the second isolation transformer; A third high-voltage switch is provided on the other branch line; The control unit is capable of controlling the source-load switching circuit so that the source-load switching circuit can switch between a voltage source mode and an electronic load mode; When the source-load switching circuit is switched to the voltage source mode, the source-load switching circuit is used as a grid simulation source with adjustable amplitude, frequency and phase for grid-related tests of energy storage power stations and energy storage converters; When the source-load switching circuit is switched to the electronic load mode, the source-load switching circuit acts as an RLC load with adjustable active power and reactive power for performing an anti-islanding test.

[0007] Furthermore, the input end of the source-load switching circuit is connected to the collecting bus in the station through a collector switch cabinet.

[0008] Furthermore, the input side of the collecting bus in the station is connected to the power grid through a main step-up transformer.

[0009] Furthermore, the output end of the source-load switching circuit is connected to an energy storage system; wherein the energy storage system includes a box-type substation, an energy storage converter and a battery compartment connected in sequence.

[0010] Furthermore, the electric energy conversion unit adopts a power electronic converter.

[0011] Furthermore, the control unit includes a first switching control module and a second switching control module; the first switching control module is used to switch the source-load switching circuit to the electronic load mode; the second switching control module is used to switch the source-load switching circuit to the voltage source mode.

[0012] Furthermore, the first switching control module can control the first high-voltage switch, the second high-voltage switch and the third high-voltage switch to be in a closed state; the second switching control module can control the first high-voltage switch and the second high-voltage switch to be in a closed state, and control the third high-voltage switch to be in an open state.

[0013] Furthermore, the control unit also includes a first adjustment module and a second adjustment module, the first adjustment module is used to adjust the active power and reactive power of the source-load switching circuit; the second adjustment module is used to adjust the amplitude, frequency and phase of the source-load switching circuit.

[0014] A method for grid-related testing of an energy storage system, based on the above-mentioned source-load integrated testing device for grid-related testing of an energy storage system, is characterized by comprising: Connect the energy storage system and source-load integrated test device to be tested in series on the busbar in the station; The source-load switching circuit is controlled by the control unit to switch the source-load switching circuit to the voltage source mode to conduct grid-connected tests of the energy storage power station and the energy storage converter; The source-load switching circuit is controlled by the control unit to switch the source-load switching circuit to the electronic load mode to perform an anti-islanding test.

[0015] Further, among them, The specific process of the grid-related test of the energy storage power station and the energy storage converter includes: The control unit controls the source-load switching circuit to close the first high-voltage switch and the second high-voltage switch and to open the third high-voltage switch, so as to switch the source-load switching circuit to the voltage source mode; The amplitude, frequency and phase of the source-load switching circuit output are adjusted by the control unit to simulate various working conditions of the power grid; The specific process of the anti-islanding test includes: The source-load switching circuit of the control unit closes the first high-voltage switch, the second high-voltage switch and the third high-voltage switch to switch the source-load switching circuit to the electronic load mode; Set the anti-islanding protection setting of the energy storage system and adjust the output power of the energy storage system to the target rated power; Adjust the active power absorbed by the integrated source-load device to be the output power of the energy storage system, and the reactive power to be 0; Adjust the load size of the source-load integrated device so that the fundamental current of each phase passing through the third high-voltage switch is less than 2% of the steady-state rated current of each phase of the energy storage system; Disconnect the third high-voltage switch, and record the time interval from disconnecting the third high-voltage switch to the energy storage system stopping supplying power to the source-load integrated device; Within the range of 95% to 105% of the initial balanced load, adjust the reactive power of the integrated source-load device by 1% or adjust the reactive power of the energy storage system by 1%. If the disconnection time of the energy storage system increases, increase the reactive power by an additional 1% or increase the reactive load by an additional 1% until the disconnection time no longer increases. If the disconnection time still increases when the initial balanced load is 95% or 105%, the reactive load shall be reduced or increased by 1%, or the reactive power shall be reduced or increased by 1% until the disconnection time no longer increases; In the test results, the three test points with the longest disconnection time are subjected to two additional repeated tests; when the three longest disconnection times appear at discontinuous 1% load addition values, all test points between the three longest disconnection times are subjected to two additional repeated tests; The target rated power is 100%, 66% or 33% of the rated power of the energy storage system.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a source-load integrated test device for grid-related tests of energy storage systems. The test device realizes flexible switching between voltage source mode and electronic load mode by integrating an electric energy conversion unit, an isolation transformer, a high-voltage switch and a control unit. In the voltage source mode, the device can be used as a grid simulation source with adjustable amplitude, frequency and phase, effectively meeting the needs of grid-related tests of energy storage power stations and energy storage converters. In the electronic load mode, it can be used as an RLC load with adjustable active power and reactive power, suitable for anti-islanding tests. The use of the test device effectively avoids the tediousness and high cost of renting a high-power mobile adjustable RLC load or using another group of energy storage subsystems as an adjustable load in traditional methods, significantly shortens the detection time period, reduces the detection cost, and because the device itself has high control accuracy, it can effectively improve the accuracy and reliability of the test.

[0017] Preferably, in the present invention, the collection line switch cabinet is connected to the collection bus in the station, thereby realizing convenient access between the test device and the energy storage system, thereby improving the flexibility and efficiency of the test.

[0018] Preferably, in the present invention, the main step-up transformer is connected to the power grid, which ensures that the test device can simulate the real power grid environment and improves the accuracy and reliability of the test results.

[0019] Preferably, in the present invention, the output end of the source-load switching circuit is directly connected to the energy storage system, including the box-type substation, the energy storage converter and the battery compartment, so as to facilitate the testing of the overall performance of the energy storage system and improve the comprehensiveness of the test.

[0020] Preferably, in the present invention, a power electronic device is used as the electric energy conversion unit, which realizes efficient and accurate conversion between alternating current and direct current, and improves the performance and flexibility of the test device.

[0021] Preferably, in the present invention, the first switching control module and the second switching control module are used to achieve fast and accurate switching of the source-load switching circuit between the voltage source mode and the electronic load mode, thereby improving the efficiency and accuracy of the test.

[0022] Preferably, in the present invention, the working principle of the switching control module is to realize the mode switching of the source-load switching circuit by controlling the closing and opening states of the high-voltage switch, thereby ensuring the smooth progress of the test.

[0023] Further preferably, in the present invention, the first regulating module and the second regulating module are respectively used to regulate the active power and reactive power as well as the amplitude, frequency and phase of the source-load switching circuit, thereby improving the accuracy and flexibility of the test.

[0024] The present invention also provides a method for grid-related testing of energy storage systems. Based on the above-mentioned source-load integrated test device for grid-related testing of energy storage systems, this method realizes the rapid construction of the test environment by connecting the energy storage system to be tested and the source-load integrated test device in series on the collecting bus in the station; the control unit is used to flexibly control the source-load switching circuit, and it can be easily switched to the voltage source mode for grid-related testing of energy storage power stations and energy storage converters, or switched to the electronic load mode for anti-islanding testing; the use of this test method avoids the cumbersome and high cost of renting a high-power mobile adjustable RLC load or using another group of energy storage subsystems as adjustable loads in the traditional method, significantly shortening the detection time cycle and reducing the detection cost. At the same time, the high-precision control characteristics of the source-load integrated test device also improve the accuracy and reliability of the test, especially in the unplanned island protection function test, it can more accurately simulate the power grid fault situation and verify the response speed and protection performance of the energy storage system. Therefore, this test method provides a more efficient, economical and accurate solution for the grid-connected detection of electrochemical energy storage systems. 。

[0025] Preferably, in the present invention, the specific process of the grid-related test and anti-islanding test of the energy storage power station and the energy storage converter, including parameter setting, test steps, repeated testing, etc., ensures the standardization of the test and the reliability of the results; at the same time, by adjusting the reactive power and load size, various operating conditions and fault conditions of the power grid are simulated, providing strong support for the performance evaluation and fault handling of the energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the structure of an existing energy storage system grid-related test device provided by an embodiment of the present invention; Figure 2 A schematic diagram of an implementation of a source-load integrated test device for grid-related tests of energy storage systems provided by an embodiment of the present invention; Figure 3 A schematic structural diagram of a source-load integrated test device for grid-related tests of energy storage systems provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail in the following specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0029] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0031] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0032] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0033] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] Example 1 Combined with what was mentioned in the background technology, currently, the grid-connected inspection items and technical regulations for electrochemical energy storage systems are based on GB / T 36547-2018 "Technical Regulations for Electrochemical Energy Storage Systems Connected to the Grid" and GB / T 36548-2018 "Test Specifications for Electrochemical Energy Storage Systems Connected to the Grid". The two standards specify the technical requirements, test items and methods for the grid-connected testing of electrochemical energy storage systems. The unplanned islanding protection function test is an important test item for the grid-connected testing of electrochemical energy storage systems. The test results can demonstrate whether the electrochemical energy storage can quickly disconnect the circuit breaker connected to the main grid when the grid has high voltage, low voltage, high frequency, low frequency and other faults, to prevent the electrochemical energy storage from matching the load of the user station, forming a small system for self-generation and self-use, and derailing from the main grid. According to the requirements of GB / T 36548-2018, the unplanned islanding protection function test of the electrochemical energy storage system requires the coordination of power supply and adjustable RLC load. The test circuit is as follows Figure 1 As shown, Figure 1 In the three-phase four-wire energy storage system, L is the phase line and N is the neutral line; in the three-phase three-wire energy storage system, L and N are both phase lines. At present, electrochemical energy storage systems are divided into distributed energy storage and centralized energy storage systems, among which centralized energy storage systems are often large in scale, such as energy storage systems configured in photovoltaic power stations, shared energy storage power stations, etc. For large-scale electrochemical energy storage systems, their minimum energy storage units (consisting of energy storage elements, energy storage converters and related accessories, etc.) are usually MW-level, such as 1.25MW, 1.75MW, 2.5MW, 3.125MW and other specifications. Since large-scale electrochemical energy storage systems (power stations) are mostly located in power generation areas, far away from urban areas, and there are no high-power adjustable RLC loads on site, if the test is carried out on site, it is necessary to rent a high-power mobile RLC load, so the test is relatively complex and the test cost is high.

[0035] The existing detection method for the unplanned islanding protection function of the electrochemical energy storage system is: 1) The energy storage system to be tested and the adjustable RLC load are connected to the public grid (or simulated grid device), such as Figure 1 For a three-phase four-wire energy storage system, Figure 1For phase-to-neutral wiring; for three-phase three-wire energy storage system, Figure 1 For alternate wiring.

[0036] 2) Set the anti-islanding protection setting value of the energy storage system and adjust the discharge power of the energy storage system to the rated power; 3) Set the voltage of the simulated power grid device (public power grid) to the nominal voltage of the energy storage system, and the frequency to the rated frequency of the energy storage system; adjust the load quality factor Q to 1.0±0.05; 4) Close switches S1, S2, and S3 until the energy storage system reaches the specified value in 2); 5) Adjust the load size so that the fundamental current of each phase passing through switch S3 is less than 2% of the steady-state rated current of each phase of the energy storage system; 6) Disconnect S3 and record the time interval from the disconnection of S3 to the energy storage system stopping supplying power to the load, i.e. the disconnection time; 7) Within the range of 95% to 105% of the initial balanced load, adjust the reactive load by 1% (or adjust the reactive power of the energy storage system by 1%). If the disconnection time of the energy storage system increases, it is necessary to increase the reactive load (or reactive power) by 1% until the disconnection time no longer increases. 8) If the disconnection time still increases when the initial balanced load is 95% or 105%, it is necessary to reduce or increase the reactive load by 1% until the disconnection time no longer increases; 9) In the test results, the three test points with the longest disconnection time shall be subjected to two additional repeated tests; when the three longest disconnection times appear at discontinuous 1% load addition values, all test points between the three longest disconnection times shall be subjected to two additional repeated tests; 10) Adjust the energy storage output power to 66% and 33% of the rated power respectively, and repeat steps 3) to 9) respectively.

[0037] When using an energy storage subsystem adjacent to the energy storage subsystem under test as an adjustable load, it is necessary to apply to the dispatcher to repeatedly stop and supply the corresponding energy storage collector line, which causes a long power outage or power supply cycle of the switch cabinet each time, resulting in an extension of the test time. It can be seen that the existing detection method has the disadvantages of long detection time cycle, high detection cost, and poor control accuracy.

[0038] In order to solve the above problems, the present invention provides a source-load integrated test device for grid-related tests of energy storage systems. This test device is used to solve the problem of no adjustable RLC load at the energy storage site in anti-islanding tests. There is no need to rent a mobile adjustable RLC load or use another set of energy storage subsystems as adjustable loads, and there is no need to apply for repeated power outages of energy storage collectors, thereby shortening the test cycle and reducing the test cost.

[0039] In order to facilitate understanding of the technical solution provided by this embodiment, the following technical terms are explained: Electrochemical energy storage system: A system that uses electrochemical batteries as energy storage carriers and stores and releases cyclic electrical energy through energy storage inverters.

[0040] Note: Generally includes battery system, energy storage converter and related auxiliary facilities. For electrochemical energy storage systems connected to voltage levels of 10 (6) kV and above, it usually also includes collection lines, step-up transformers, etc.

[0041] Energy storage inverter: a device that connects the battery system with the power grid or load to achieve bidirectional power conversion.

[0042] Energy storage battery: An electrochemical cell used as an energy carrier in energy storage systems.

[0043] Energy storage unit: The smallest subunit in the electrochemical energy storage system, including battery compartment, energy storage inverter, box transformer and related auxiliary facilities.

[0044] Grid connection point: For energy storage systems with step-up transformers, it refers to the bus or node on the high-voltage side of the step-up transformer. For energy storage systems without step-up transformers, it refers to the output aggregation point of the energy storage system.

[0045] Public connection point: The point where the energy storage system is connected to the public power grid.

[0046] Hot standby state: The energy storage system is ready for operation, equipment protection and automatic devices are in normal operation, and energy can be exchanged with the power grid by issuing control instructions to the energy storage system.

[0047] RLC load: A load composed of resistance, capacitance, inductance and a control system, and the resistance, capacitance and inductance are adjustable.

[0048] Load quality factor: refers to the ratio of the active power and reactive power provided by the load to the power supply.

[0049] Unplanned islanding: An unplanned, uncontrolled islanding state. In this state, if the power supply in the island continues to supply power to the grid it is connected to, it will cause certain harm.

[0050] like Figure 2 and Figure 3 As shown, this embodiment provides a source-load integrated test device for grid-related tests of energy storage systems, including: a source-load switching circuit and a control unit ( Figure 2 The control unit is used to control the source-load switching circuit; the source-load switching circuit is connected between the collecting bus in the station and the unit under test (the energy storage system to be tested); the source-load switching circuit is connected between the collecting bus and the unit under test (the energy storage system to be tested) through the collecting line switch cabinet ( Figure 2S4) is connected to the collecting bus in the station; the collecting bus in the station is connected in series with the 110KV power grid through a 110KV or 35KV main step-up transformer.

[0051] In this embodiment, the energy storage system to be tested includes a box-type substation, an energy storage converter and a battery compartment connected in sequence. The battery compartment is connected to the low-voltage AC side of the energy storage transformer through the energy storage converter, and the high-voltage AC side of the energy storage transformer serves as the high-voltage AC side of the unit under test.

[0052] In practical applications, the battery compartment can be an energy storage battery, an electrochemical battery that acts as an energy carrier in an energy storage system. The energy storage unit in this embodiment is generally the smallest subunit in an electrochemical energy storage system, including a battery compartment, an energy storage converter, a box transformer, and related auxiliary facilities.

[0053] In this embodiment, the source-load switching circuit includes two parallel branches connected between the collecting bus in the station and the unit under test (the energy storage system to be tested); wherein the second high-voltage switch, the second isolation transformer, the power conversion unit for realizing the conversion from the grid-end AC to the load-end AC, the first isolation transformer, and the first high-voltage switch connected in series in sequence serve as the first branch; the third high-voltage switch is connected to the second branch; and the control unit can control the power conversion unit, the first isolation transformer, the first high-voltage switch, the second isolation transformer, and the second high-voltage switch.

[0054] In this embodiment, the power conversion unit adopts a power electronic device, also known as a power electronic converter, which is connected between the second isolation transformer and the first isolation transformer; the power electronic converter can accurately control and adjust the direction and size of the power flow of the power system by controlling the waveform of the voltage and current of the electrode; and can realize the conversion between alternating current (AC) and direct current (DC).

[0055] The present embodiment provides a source-load integrated test device for grid-related tests of energy storage systems, which is mainly used in large-scale electrochemical energy storage power stations. The source-load integrated test device consists of a high-voltage switch, an isolation transformer, a power electronic converter and a control system. It has a source-load integrated function and can be switched arbitrarily between a voltage source mode and an electronic load mode.

[0056] In this embodiment, the control unit includes a first switching control module and a second switching control module as well as a first adjustment module and a second adjustment module; wherein the switching control module is used to switch the source-load switching circuit to the electronic load mode; the second switching control module is used to switch the source-load switching circuit to the voltage source mode; the first adjustment module is used to adjust the active power and reactive power of the source-load switching circuit; the second adjustment module is used to adjust the amplitude, frequency and phase of the source-load switching circuit.

[0057] In this embodiment, the high voltage switch ( Figure 2 Specifically, the first high-voltage switch, the second high-voltage switch, and the third high-voltage switch can be switch electronic components such as relays, electronic switches, and mechanical switches. This application does not limit their specific types, and they are all within the protection scope of this application.

[0058] This embodiment also provides a method for grid-related testing of an energy storage system. Based on the above-mentioned source-load integrated testing device for grid-related testing of an energy storage system, the specific steps are as follows: 1) The energy storage system to be tested and the source-load integrated test device are connected in series to the public power grid (busbar within the station), such as Figure 2 As shown; 2) If voltage adaptability, frequency adaptability, power quality adaptability, high voltage ride-through, low voltage ride-through and interlocking voltage fault ride-through tests are to be conducted: the source-load integrated device is set to work in power supply mode, high-voltage switches S1 and S2 are closed, high-voltage switch S3 is opened, and the output voltage amplitude, frequency and phase of the device are adjusted to simulate various working conditions of the power grid for testing; 3) If an unplanned island protection function test is performed: set the source-load integrated device to work in load mode, close high-voltage switches S3, S1, and S2 in sequence, and connect the source-load integrated device and the energy storage system under test to the output line under switch S3; 4) Set the anti-islanding protection setting of the energy storage system and adjust the discharge power of the energy storage system to 100% of the rated power; 5) Adjust the active power absorbed by the source-load integrated device to the output power of the energy storage system, and the reactive power to 0; 6) Adjust the load size of the source-load integrated device until the fundamental current of each phase passing through switch S3 is less than 2% of the steady-state rated current of each phase of the energy storage system; 7) Disconnect S3 and record the time interval from the disconnection of S3 to the energy storage system stopping supplying power to the source-load integrated device (load), i.e. the disconnection time; 8) Within the range of 95% to 105% of the initial balanced load, adjust the reactive power of the source-load integrated device by 1% (or adjust the reactive power of the energy storage system by 1%). If the disconnection time of the energy storage system increases, it is necessary to increase the reactive load (or reactive power) by 1% until the disconnection time no longer increases; 9) If the disconnection time still increases when the initial balanced load is 95% or 105%, it is necessary to reduce or increase the reactive load or reactive power by 1% until the disconnection time no longer increases; 10) In the test results, the three test points with the longest disconnection time shall be subjected to two additional repeated tests; when the three longest disconnection times appear at discontinuous 1% load addition values, all test points between the three longest disconnection times shall be subjected to two additional repeated tests; 11) Adjust the output power of the energy storage system to 66% and 33% of the rated power respectively, and repeat steps 5) to 10) respectively.

[0059] It can be seen that the key point of the source-load integrated test device and test method for grid-related tests of energy storage systems provided in this embodiment is that, with the cooperation of the high-voltage switch, the source-load integrated test device can be switched to power supply mode (voltage source mode) or load mode (electronic load mode): in power supply mode, the source-load integrated test device serves as a grid simulation source with arbitrarily adjustable amplitude, frequency and phase, and can perform grid-related tests of energy storage power stations and energy storage converters such as voltage adaptability, frequency adaptability, power quality adaptability, high voltage ride-through, low voltage ride-through and interlocking voltage fault ride-through; in load mode, the source-load integrated test device serves as an RLC load with arbitrarily adjustable active power and reactive power, and can perform unplanned islanding protection function tests (anti-islanding tests).

[0060] In summary, the present invention provides a source-load integrated test device for grid-related tests of energy storage systems, which has the following advantages over existing test measures: This integrated source-load test device is mainly aimed at large-scale electrochemical energy storage systems. It switches the working mode according to the test requirements, and when conducting unplanned island protection function tests, it adjusts the size of active and reactive power in real time according to the test conditions to meet the test requirements. The use of this test device can effectively solve the problem of no adjustable RLC load at the energy storage site in the anti-islanding test. There is no need to rent a high-power mobile adjustable RLC load or use another set of energy storage subsystems as an adjustable load, and there is no need to apply for repeated power outages of energy storage collectors. The integrated source-load test device for grid-related tests of energy storage systems provided by the present invention can flexibly switch the working mode, and there is no need to disconnect cables twice during the test and apply for collector switch cabinets ( Figure 2 S4) power outage in the test shortens the test cycle; in load mode, the generated power is fed back to the grid to save energy; unplanned island tests do not require the rental of RLC loads, which reduces test costs, shortens the test cycle, and improves test efficiency.

[0061] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention.

Claims

1. A source-load integrated test device for grid-related tests of energy storage systems, characterized in that: It includes a source-load switching circuit and a control unit; the source-load switching circuit includes two parallel branches, wherein one branch is provided with: An electric energy conversion unit, used to realize the conversion of AC power from the grid end to AC power from the load end; A first isolation transformer and a second isolation transformer are respectively connected to two sides of the power conversion unit; a first high-voltage switch connected to the first isolation transformer, and a second high-voltage switch connected to the second isolation transformer; A third high-voltage switch is provided on the other branch line; The control unit is capable of controlling the source-load switching circuit so that the source-load switching circuit can switch between a voltage source mode and an electronic load mode; When the source-load switching circuit is switched to the voltage source mode, the source-load switching circuit is used as a grid simulation source with adjustable amplitude, frequency and phase for grid-related tests of energy storage power stations and energy storage converters; When the source-load switching circuit is switched to the electronic load mode, the source-load switching circuit acts as an RLC load with adjustable active power and reactive power for performing an anti-islanding test.

2. The source-load integrated test device for grid-related test of energy storage system according to claim 1, characterized in that: The input end of the source-load switching circuit is connected to the collecting bus in the station through a collecting line switch cabinet.

3. The source-load integrated test device for grid-related test of energy storage system according to claim 2, characterized in that: The input side of the collecting bus in the station is connected to the power grid through a main step-up transformer.

4. The source-load integrated test device for grid-related test of energy storage system according to claim 1, characterized in that: The output end of the source-load switching circuit is connected to an energy storage system; wherein the energy storage system includes a box-type substation, an energy storage converter and a battery compartment connected in sequence.

5. The source-load integrated test device for grid-related test of energy storage system according to claim 1, characterized in that: The electric energy conversion unit adopts a power electronic converter.

6. The source-load integrated test device for grid-related test of energy storage system according to claim 1, characterized in that: The control unit includes a first switching control module and a second switching control module; the first switching control module is used to switch the source-load switching circuit to an electronic load mode; the second switching control module is used to switch the source-load switching circuit to a voltage source mode.

7. The source-load integrated test device for grid-related test of energy storage system according to claim 6, characterized in that: The first switching control module can control the first high-voltage switch, the second high-voltage switch and the third high-voltage switch to be in a closed state; the second switching control module can control the first high-voltage switch and the second high-voltage switch to be in a closed state and control the third high-voltage switch to be in an open state.

8. The source-load integrated test device for grid-related test of energy storage system according to claim 6, characterized in that: The control unit also includes a first regulating module and a second regulating module, wherein the first regulating module is used to regulate the active power and reactive power of the source-load switching circuit; and the second regulating module is used to regulate the amplitude, frequency and phase of the source-load switching circuit.

9. A method for grid-connected testing of an energy storage system, based on the source-load integrated testing device for grid-connected testing of an energy storage system according to any one of claims 1 to 8, characterized in that: include: Connect the energy storage system and source-load integrated test device to be tested in series on the busbar in the station; The source-load switching circuit is controlled by the control unit to switch the source-load switching circuit to the voltage source mode to conduct grid-connected tests of the energy storage power station and the energy storage converter; The source-load switching circuit is controlled by the control unit to switch the source-load switching circuit to the electronic load mode to perform an anti-islanding test.

10. The energy storage system grid-related test method according to claim 9, characterized in that: in, The specific process of the grid-related test of the energy storage power station and the energy storage converter includes: The control unit controls the source-load switching circuit to close the first high-voltage switch and the second high-voltage switch and to open the third high-voltage switch, so as to switch the source-load switching circuit to the voltage source mode; The amplitude, frequency and phase of the source-load switching circuit output are adjusted by the control unit to simulate various working conditions of the power grid; The specific process of the anti-islanding test includes: The source-load switching circuit of the control unit closes the first high-voltage switch, the second high-voltage switch and the third high-voltage switch to switch the source-load switching circuit to the electronic load mode; Set the anti-islanding protection setting of the energy storage system and adjust the output power of the energy storage system to the target rated power; Adjust the active power absorbed by the integrated source-load device to be the output power of the energy storage system, and the reactive power to be 0; Adjust the load size of the source-load integrated device so that the fundamental current of each phase passing through the third high-voltage switch is less than 2% of the steady-state rated current of each phase of the energy storage system; Disconnect the third high-voltage switch, and record the time interval from disconnecting the third high-voltage switch to the energy storage system stopping supplying power to the source-load integrated device; Within the range of 95% to 105% of the initial balanced load, adjust the reactive power of the integrated source-load device by 1% or adjust the reactive power of the energy storage system by 1%. If the disconnection time of the energy storage system increases, increase the reactive power by an additional 1% or increase the reactive load by an additional 1% until the disconnection time no longer increases. If the disconnection time still increases when the initial balanced load is 95% or 105%, the reactive load shall be reduced or increased by 1%, or the reactive power shall be reduced or increased by 1% until the disconnection time no longer increases; In the test results, the three test points with the longest disconnection time are subjected to two additional repeated tests; when the three longest disconnection times appear at discontinuous 1% load addition values, all test points between the three longest disconnection times are subjected to two additional repeated tests; The target rated power is 100%, 66% or 33% of the rated power of the energy storage system.

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