Grid-connected testing device of network-forming type energy storage system

Abstract

The utility model discloses a grid-connected testing device of a grid-forming type energy storage system. The grid-connected testing device comprises a microprocessor, a power grid simulator, a first transformer, a DC / AC converter, a second transformer, a rectifier, a power inverter, a third transformer and a fourth transformer. The output end of the power grid simulator is provided with three branches, the first branch is connected to the first transformer and the to-be-tested energy storage system, the second branch is connected to the first end of a primary winding of the second transformer, the second end is connected to the to-be-tested energy storage system, and the third branch is connected to the fourth transformer. The output end of the fourth transformer is connected to the input end of the third transformer through the rectifier and the power inverter filter, and the output end of the third transformer is connected to the energy storage system to be tested. According to the utility model, a real grid-connected operation environment can be simulated to test power grid adaptability, test items comprise voltage adaptability, frequency adaptability, three-phase voltage imbalance and the like, the test functions are diversified, one machine has multiple purposes, the use is convenient and flexible, and the application range is wide.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of power equipment, concretely relates to a grid -connected test device of network construction type energy storage system. BACKGROUND

[0002] The electrochemical energy storage system is a kind of energy storage system using electrochemical reaction to convert electrical energy into chemical energy, and when needed, chemical energy is converted into electrical energy again.The working principle of electrochemical energy storage system is based on electrochemical reaction.In the charging process, the external power supply provides electrical energy to the system, so that the negative electrode occurs oxidation reaction, the positive electrode occurs reduction reaction, the electron flows from the negative electrode to the positive electrode, the ion in the electrolyte flows from the positive electrode to the negative electrode, and the electrical energy is converted into chemical energy and stored in the electrode and electrolyte.In the discharging process, the chemical energy stored in the electrode and electrolyte is converted into electrical energy, the negative electrode occurs reduction reaction, the positive electrode occurs oxidation reaction, the electron flows out from the negative electrode, flows to the positive electrode through the external circuit, the ion in the electrolyte flows from the negative electrode to the positive electrode, and the electrical energy is released to the circuit.

[0003] When the electrochemical energy storage system is in grid-connected operation, its key performance indicators, such as power quality, grid-connected charging and discharging law, power regulation response characteristics and grid-connected protection function, all play a crucial role in the safe and stable operation of the power grid.Therefore, comprehensive and accurate grid-connected testing of electrochemical energy storage system is necessary to ensure its stable and efficient operation after grid connection, which has become a core link in the operation and management of power system.

[0004] Some devices capable of realizing grid-connected testing are recorded in the prior art, for example, reference 1 records:

[0005] Reference 1: Chinese patent document with publication number CN 221667939 U

[0006] Reference 1 records a grid-connected testing device for electrochemical energy storage system, belonging to the technical field of power grid testing equipment, including power grid simulator, circuit breaker QF1, step-up transformer, rectifier, current-limiting resistor R1, capacitor C1, capacitor C2, inverter circuit, current collector, voltage collector, filter circuit, step-down transformer, current-limiting resistor R2, voltage dividing resistor R3, circuit breaker QF2, microprocessor and power supply for the whole system.The device can comprehensively and systematically test the key performance indicators of electrochemical energy storage system under grid-connected state by integrating power grid simulator, inverter circuit, filter circuit and multiple sets of precision measuring elements, to ensure its stable and efficient operation in power grid.In addition, the built-in circuit breakers QF1 and QF2 in the device can effectively isolate faults during testing, protecting the safety of the measured energy storage system and other equipment.

[0007] The reference 1 discloses a method for realizing grid-connected test of energy storage system. However, the method for realizing grid-connected test of energy storage system is not limited to the above method, and therefore the applicant proposes a grid-connected test of energy storage system different from the prior art. Practical new type content

[0008] The utility model discloses a kind of technical ideas and grid-connected test equipment of energy storage system different from prior art, can realize the comprehensive grid-connected test of energy storage system.

[0009] The utility model discloses a kind of technical ideas and grid-connected test equipment of energy storage system different from prior art, can realize the comprehensive grid-connected test of energy storage system.

[0010] The output end of the power grid simulator has three branches, the first branch is connected to the input end of the first transformer, and a first switch is provided between the power grid simulator and the input end of the first transformer, and the output end of the first transformer is connected to the energy storage system to be tested.

[0011] The second branch of the output end of the power grid simulator is connected to the first end of the primary winding of the second transformer, the second end of the primary winding of the second transformer is connected to the energy storage system to be tested, and the second branch further includes a DC / AC converter, the input end of the DC / AC converter is connected to the power grid simulator, the output end of the DC / AC converter is connected to the secondary winding of the second transformer, and a second switch is provided at the front end of the second branch.

[0012] The third branch of the output end of the power grid simulator is connected to the input end of the fourth transformer, the output end of the fourth transformer is connected to the input end of the power inverter through the rectifier, the output end of the power inverter is connected to the input end of the third transformer through the filter, the output end of the third transformer is connected to the energy storage system to be tested, a third switch is provided between the power grid simulator and the input end of the fourth transformer, and a fourth switch is provided at the front end of the energy storage system to be tested.

[0013] As a further optimization of the grid-connected test device for the network-type energy storage system, a current collector is provided between the filter and the third transformer.

[0014] As a further optimization of the grid-connected test device for the network-type energy storage system, a current collector is provided between the DC / AC converter and the second transformer.

[0015] As further optimization of the grid-connected test device of the network-constructing energy storage system of the utility model, the first switch, the second switch and the third switch are mechanical switches or electronic switches.

[0016] As further optimization of the grid-connected test device of the network-constructing energy storage system of the utility model, the power inverter is a converter with bidirectional energy flow.

[0017] As further optimization of the grid-connected test device of the network-constructing energy storage system of the utility model, the power inverter is a converter with bidirectional energy flow.

[0018] As further optimization of the grid-connected test device of the network-constructing energy storage system of the utility model, the microprocessor adopts STM32F103 single-chip microcomputer.

[0019] The utility model has the following beneficial effects: the utility model can simulate real grid-connected operation environment to test power grid adaptability, test items include voltage adaptability, frequency adaptibility and three-phase voltage imbalance etc., test functions are diversified, so that it is multipurpose, convenient and flexible to use, and has wide application range. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is the structural diagram of the grid-connected test device of the utility model. DETAILED DESCRIPTION

[0021] In order to better understand the utility model, the contents of the utility model are further illustrated below in combination with examples, but the contents of the utility model are not limited to the following examples.

[0022] As shown in the figure: a kind of grid-connected test device of network-constructing energy storage system, including microprocessor, power grid simulator, first transformer, DC / AC converter, second transformer, rectifier, power inverter, third transformer and fourth transformer, microprocessor and DC / AC converter and power inverter are electrically connected.

[0023] Microprocessor adopts STM32F103 single-chip microcomputer. STM32F103 series single-chip microcomputer is a 32-bit microcontroller based on ARM Cortex-M3 core launched by STMicroelectronics company.

[0024] The power grid simulator is an IT7900 series power grid simulator or an AGS series power grid simulator. The IT7900 series power grid simulator is widely used in grid-connected testing and can simulate various power grid conditions. The IT7900 series simulator has full four-quadrant operating capability and can be used as a power source and an electronic load. This means that it can simulate various load conditions in the power grid, including inductive, capacitive, and nonlinear loads, as well as provide energy feedback functionality. This feature is particularly important for testing grid-connected devices such as grid-connected inverters and energy storage systems, which need to operate stably under different grid conditions.

[0025] The power inverter is a power converter with bidirectional energy flow, which can not only convert direct current (DC) to alternating current (AC) for AC load use, but also convert AC back to DC, realizing bidirectional energy flow.

[0026] The output end of the power grid simulator has three branches. The first branch is connected to the input end of the first transformer, and a first switch is arranged between the power grid simulator and the input end of the first transformer. The output end of the first transformer is connected to the energy storage system to be tested.

[0027] The second branch of the output end of the power grid simulator is connected to the first end of the primary winding of the second transformer, and the second end of the primary winding of the second transformer is connected to the energy storage system to be tested. The second branch further includes a DC / AC converter, the input end of the DC / AC converter is connected to the power grid simulator, the output end of the DC / AC converter is connected to the secondary winding of the second transformer, and the front end of the second branch is provided with a second switch.

[0028] The third branch of the output end of the power grid simulator is connected to the input end of the fourth transformer, the output end of the fourth transformer is connected to the input end of the power inverter through a rectifier, the output end of the power inverter is connected to the input end of the third transformer through a filter, the output end of the third transformer is connected to the energy storage system to be tested, a third switch is arranged between the power grid simulator and the input end of the fourth transformer, and a fourth switch is arranged at the front end of the energy storage system to be tested.

[0029] The first switch, the second switch, and the third switch are mechanical switches or electronic switches. Mechanical switches generally refer to switches that can be manually operated physically, such as common tactile switches or toggle switches. Electronic switches may be controlled by circuits, such as non-contact switches implemented using transistors or relays.

[0030] A current collector is arranged between the filter and the third transformer, and a current collector is arranged between the DC / AC converter and the second transformer.

[0031] The first switch is used for controlling the actual grid access or the simulated grid access, when the first switch is closed, the device under test is powered by the actual grid, and is usually used for waiting for test conditions; when the test conditions are met, the first switch is opened, the test process is entered, and the device under test is powered by the simulated grid.

[0032] The grid adaptability function test, wherein for the voltage adaptability and three-phase imbalance adaptability test, before the test, the first switch and the fourth switch are closed, and all the other switches are in the open state, the device under test is powered by the actual grid, and is waiting for the test. When the test conditions are met, the second switch is closed, the first switch is opened, the device under test is powered by the simulated grid, and the test is started. The rated voltage is provided by the grid access, the DC / AC converter is controlled to provide the deviation voltage and the harmonic voltage meeting the test requirements, the voltage adaptability, the three-phase imbalance adaptability and the flicker adaptability test requirements are realized by superimposing the rated voltage and the deviation voltage through the second transformer, and the harmonic adaptability test requirements are realized by superimposing the fundamental voltage and the harmonic voltage.

[0033] The frequency adaptability test, before the test, the first switch and the fourth switch are closed, and all the other switches are in the open state, the device under test is powered by the actual grid, and is waiting for the test. When the test conditions are met, the third switch is closed, the first switch is opened, the device under test is powered by the simulated grid, and the test is started. The frequency adaptability is realized by completely controlling the power inverter to output the required frequency range, transmitting through the parallel transformer and matching the voltage to realize the test requirements.

[0034] The above describes the specific embodiments of the utility model. It should be understood that the utility model is not limited to the above specific embodiments, and various modifications or changes can be made by those skilled in the art within the scope of claims, which does not affect the essential content of the utility model.

Claims

1.A grid-connected test device for a grid-forming energy storage system, characterized in that: The power grid simulator, the first transformer, the DC / AC converter, the second transformer, the rectifier, the power inverter, the third transformer and the fourth transformer, the microprocessor is electrically connected with the DC / AC converter and the power inverter; The output end of the power grid simulator has three branches, the first branch is connected to the input end of the first transformer, and the first switch is arranged between the power grid simulator and the input end of the first transformer, and the output end of the first transformer is connected to the energy storage system to be tested; The second branch of the output end of the power grid simulator is connected to the first end of the primary winding of the second transformer, the second end of the primary winding of the second transformer is connected to the energy storage system to be tested, the second branch further comprises the DC / AC converter, the input end of the DC / AC converter is connected to the power grid simulator, the output end of the DC / AC converter is connected to the secondary winding of the second transformer, and the front end of the second branch is provided with the second switch; The third branch of the output end of the power grid simulator is connected to the input end of the fourth transformer, the output end of the fourth transformer is connected to the input end of the power inverter through the rectifier, the output end of the power inverter is connected to the input end of the third transformer through the filter, the output end of the third transformer is connected to the energy storage system to be tested, the third switch is arranged between the power grid simulator and the input end of the fourth transformer, and the fourth switch is arranged at the front end of the energy storage system to be tested. 2.The grid-connected test device for a network-constructed energy storage system according to claim 1, wherein: The current collector is arranged between the filter and the third transformer. 3.The grid-connected test device for network-constructed energy storage system of claim 1, wherein: The current collector is arranged between the DC / AC converter and the second transformer. 4.The grid-connected test device for network-constructed energy storage system of claim 1, wherein: The first switch, the second switch and the third switch are mechanical switches or electronic switches. 5.The grid-connected test device for network-constructed energy storage system of claim 1, wherein: The power inverter is a converter with bidirectional energy flow. 6.The grid-connected test device for network-constructed energy storage system of claim 1, wherein: The power grid simulator is an IT7900 series power grid simulator or an AGS series power grid simulator. 7.The grid-connected test device of the network-constructed energy storage system according to claim 1, wherein: The microprocessor adopts an STM32F103 single-chip microcomputer.

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