Energy storage converter back-to-back test system

Abstract

The utility model belongs to the technical field of energy storage converter testing, and aims to provide a back-to-back testing system for an energy storage converter. According to the technical scheme, the back-to-back test system for the energy storage converters comprises a first energy storage converter, a second energy storage converter and an isolation transformer, the direct current end of the first energy storage converter is connected with the direct current end of the second energy storage converter; the alternating current end of the first energy storage converter is connected with the primary side of the isolation transformer, and the alternating current end of the first energy storage converter is connected into an alternating current power grid in parallel; and the alternating current end of the second energy storage converter is connected with the secondary side of the isolation transformer. According to the utility model, the hardware cost of the back-to-back test platform can be reduced, and electric energy can be saved.

Description

Technical Field

[0001] The utility model belongs to the technical field of energy storage converter testing, and particularly relates to a back-to-back testing system for an energy storage converter. Background Art

[0002] At present, the development of low-carbon and green energy is being vigorously promoted. As an important part of low-carbon energy, energy storage systems are widely used in various fields. The power conversion system (PCS) of energy storage is an important part of the energy storage system. In the energy storage system, the PCS is responsible for converting alternating current in the power grid into direct current (rectification process) to charge the energy storage battery; at the same time, when the battery needs to discharge, it converts direct current into alternating current (inversion process) to supply power to the power grid or users.

[0003] At present, when testing or aging an energy storage converter, a back-to-back scheme of the energy storage converter is often adopted. For example, a back-to-back testing platform for an energy storage converter disclosed in a Chinese patent with the publication number CN220730330U, the DC output side of the DC source is respectively connected to the DC terminals of two energy storage converters, and the AC terminals of the two energy storage converters (1# PCS and 2# PCS) are connected through an isolation transformer. In the implementation process, terminal devices such as a computer can communicate with the two energy storage converters through a network cable and a switch to achieve control of the energy storage converter. For example, the operation mode of 1# PCS can be controlled to be an off-grid operation mode and started, and an AC voltage is output to provide the required AC voltage for 2# PCS through the isolation transformer; the operation mode of 2# PCS can also be controlled to be a constant power mode, set its power value and start; energy circulation occurs between the two energy storage converters, and the DC voltage source provides energy loss.

[0004] However, in the process of using the prior art, the inventor found that there are at least the following problems in the prior art:

[0005] In the prior art, at least one DC voltage source and an isolation transformer are required, and the hardware cost is relatively high. Summary of the Utility Model

[0006] In order to solve the above technical problems to at least a certain extent, the utility model provides a back-to-back testing system for an energy storage converter.

[0007] In order to achieve the above object, the utility model adopts the following technical solutions:

[0008] A back-to-back test system for an energy storage converter, comprising a first energy storage converter, a second energy storage converter and an isolation transformer; the DC terminals of the first energy storage converter and the second energy storage converter are connected; the AC terminal of the first energy storage converter is connected to the primary side of the isolation transformer, and the AC terminal of the first energy storage converter is connected in parallel to the AC power grid; the AC terminal of the second energy storage converter is connected to the secondary side of the isolation transformer.

[0009] In a possible design, the back-to-back test system for the energy storage converter further comprises a test terminal and a switch; the test terminal is electrically connected to the controlled terminals of the first energy storage converter and the second energy storage converter respectively through the switch.

[0010] In a possible design, the rated AC power of the first energy storage converter is 125 kW, the rated AC voltage is 380 V, and the DC voltage input range is 680 - 950 V.

[0011] In a possible design, the rated AC power of the second energy storage converter is 125 kW, the rated AC voltage is 380 V, and the DC voltage input range is 680 - 950 V.

[0012] In a possible design, the rated capacity of the isolation transformer is 150 kVA, the primary side voltage is 400 V, and the secondary side voltage is 400 V.

[0013] In a possible design, the operating mode of the first energy storage converter is a constant DC voltage mode.

[0014] In a possible design, the range of the constant DC voltage value of the first energy storage converter is 680 - 950 V.

[0015] In a possible design, the operating mode of the second energy storage converter is a constant power mode.

[0016] In a possible design, the range of the power value of the second energy storage converter is -125 - 125 kW.

[0017] In a possible design, the rated supply voltage of the AC power grid is 380 V.

[0018] The beneficial effects of the present utility model are mainly reflected in that the present utility model can reduce the hardware cost of the back-to-back test platform and save electric energy at the same time. Specifically, the energy storage converter back-to-back test system in the present utility model includes a first energy storage converter, a second energy storage converter and an isolation transformer. During implementation, the constant DC voltage mode of the first energy storage converter (that is, input AC voltage and output stable DC voltage) can be used to provide DC voltage for the second energy storage converter for energy conversion, and the energy loss is provided by the AC power grid, thus eliminating a DC voltage source, reducing the hardware cost, and saving the electric energy of the DC voltage source. At the same time, through the energy storage converter back-to-back test system in the present utility model, the operation stability and efficiency and other parameters of the first energy storage converter and the second energy storage converter can be evaluated more realistically, ensuring their reliability and performance in actual applications. Description of the Drawings

[0019] Figure 1 is the circuit schematic diagram of the energy storage converter back-to-back test system in the embodiment;

[0020] Wherein: 1 - the first energy storage converter; 2 - the second energy storage converter; 3 - the isolation transformer; 4 - the test terminal; 5 - the switch. Detailed Embodiments

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the present utility model in combination with the drawings and the descriptions of the embodiments or the prior art. Obviously, the following descriptions of the structures of the drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. It should be noted here that the descriptions of these embodiments are used to help understand the present utility model, but do not constitute a limitation to the present utility model.

[0022] It should be understood that although terms such as first and second may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, the first unit can be called the second unit, and similarly, the second unit can be called the first unit, without departing from the scope of the exemplary embodiments of the present utility model.

[0023] Embodiment 1:

[0024] As Figure 1As shown in the figure, this embodiment provides a back-to-back test system for an energy storage converter, which includes a first energy storage converter 1, a second energy storage converter 2, and an isolation transformer 3; the DC terminals of the first energy storage converter 1 and the second energy storage converter 2 are connected; the AC terminal of the first energy storage converter 1 is connected to the primary side of the isolation transformer 3, and the AC terminal of the first energy storage converter 1 is connected in parallel to the AC power grid; the AC terminal of the second energy storage converter 2 is connected to the secondary side of the isolation transformer 3.

[0025] This embodiment can reduce the hardware cost of the back-to-back test platform and save electric energy at the same time. Specifically, the back-to-back test system for the energy storage converter in this embodiment includes a first energy storage converter 1, a second energy storage converter 2, and an isolation transformer 3. During the implementation process, the constant DC voltage mode of the first energy storage converter 1 (that is, input AC voltage and output stable DC voltage) can be used to provide DC voltage for the second energy storage converter 2 for energy conversion, and the energy loss is provided by the AC power grid, thus eliminating a DC voltage source, reducing the hardware cost, and saving the electric energy of the DC voltage source. At the same time, through the back-to-back test system for the energy storage converter in this embodiment, the operating stability and efficiency and other parameters of the first energy storage converter 1 and the second energy storage converter 2 can be evaluated more realistically, ensuring their reliability and performance in actual applications.

[0026] Specifically, in this embodiment, in the energy storage converter that constitutes the first energy storage converter 1 or the second energy storage converter 2, both include a DC input filter, an input-side DC circuit breaker, a DC-side boost / buck converter, an inverter, an output filter, and an output-side AC circuit breaker. Among them, the input terminal of the DC input filter constitutes the DC terminal of the energy storage converter, which is used to receive DC electric energy from an energy storage device (such as a battery pack). The DC input filter is used to eliminate voltage harmonics and filter electromagnetic interference. The input-side DC circuit breaker is used to control the connection and disconnection of DC electric energy. The DC-side boost / buck converter is used to convert DC electric energy into a voltage level suitable for the inverter to use. The inverter is used to convert DC electric energy into AC electric energy, usually using PWM or other modulation techniques. The output filter is used to eliminate harmonics generated by the inverter and filter electromagnetic interference. The output-side AC circuit breaker is used to control the connection and disconnection of the output AC electric energy. The output terminal of the output-side AC circuit breaker constitutes the AC terminal of the energy storage converter. During the operation of the energy storage converter, the DC input filter, the input-side DC circuit breaker, and the DC-side boost / buck converter can process the DC electric energy provided by the energy storage device and convert it into a voltage and current suitable for the inverter to use; the inverter can convert the processed DC electric energy into AC electric energy and output it to the power grid or load, and reduce harmonics and filter electromagnetic interference through the output filter.

[0027] In this embodiment, the back-to-back test system of the energy storage converter further includes a test terminal 4 and a switch 5; the test terminal 4 is electrically connected to the controlled terminals of the first energy storage converter 1 and the second energy storage converter 2 respectively through the switch 5.

[0028] Specifically, in this embodiment, the test terminal 4 can be, but is not limited to, a computer. When the test terminal 4 is a computer, it is electrically connected to the controlled terminals of the first energy storage converter 1 and the second energy storage converter 2 respectively through the switch 5 based on a network cable to control the first energy storage converter 1 and the second energy storage converter 2. During the implementation process, in the energy storage converters that make up the first energy storage converter 1 or the second energy storage converter 2, there is a host computer connected to the energy storage converter control chip through a communication board. The host computer constitutes the controlled terminal of the energy storage converter, so as to realize control over the operation mode and parameter modification of the energy storage converter through the test terminal 4.

[0029] It should also be understood that in this embodiment, when the test terminal 4 controls the first energy storage converter 1 and the second energy storage converter 2, it is realized based on their different IP (Internet Protocol) addresses, which will not be elaborated here.

[0030] In this embodiment, the rated AC power of the first energy storage converter 1 is 125 kW (kilowatt), the rated AC voltage is 380 V (volt), and the DC voltage input range is 680 - 950 V. That is to say, in this embodiment, the rated output power of the first energy storage converter 1 is 125 kilowatts. Under normal operating conditions, the first energy storage converter 1 can output 125 kilowatts of AC electric energy to the power grid. And under normal operating conditions, the AC voltage output by the first energy storage converter 1 to the power grid is 380 volts, and the acceptable DC voltage range is between 680 volts and 950 volts.

[0031] In this embodiment, the rated AC power of the second energy storage converter 2 is 125 kW, the rated AC voltage is 380 V, and the DC voltage input range is 680 - 950 V. That is to say, in this embodiment, the rated output power of the second energy storage converter 2 is 125 kilowatts. Under normal operating conditions, the second energy storage converter 2 can output 125 kilowatts of AC electric energy to the power grid. And under normal operating conditions, the AC voltage output by the second energy storage converter 2 to the power grid is 380 volts, and the acceptable DC voltage range is between 680 volts and 950 volts.

[0032] In this embodiment, the rated capacity of the isolation transformer 3 is 150 kVA (kilovolt-ampere), the primary side voltage is 400 V, and the secondary side voltage is 400 V. That is, in this embodiment, the rated power of the isolation transformer 3 is 150 kilovolt-ampere, which means it can withstand a load with a maximum power of 150 kVA, and both the primary side input voltage and the secondary side output voltage are 400 volts.

[0033] In this embodiment, the operation mode of the first energy storage converter 1 is the constant DC voltage mode.

[0034] Specifically, the range of the constant DC voltage value of the first energy storage converter 1 is 680 - 950 V.

[0035] Specifically, during the implementation of this embodiment, based on the upper computer in the first energy storage converter 1, the operation mode of the first energy storage converter 1 is controlled to be the constant DC voltage mode, and the constant DC voltage value (680 - 950 V) of the first energy storage converter 1 is set as needed and then started.

[0036] In this embodiment, the operation mode of the second energy storage converter 2 is the constant power mode.

[0037] Specifically, the range of the power value of the second energy storage converter 2 is -125 - 125 kW.

[0038] Specifically, during the implementation of this embodiment, based on the upper computer in the second energy storage converter 2, the operation mode of the second energy storage converter 2 is controlled to be the constant power mode, and the power value (-125 - 125 kW) of the second energy storage converter 2 is set as needed and then started.

[0039] Specifically, in this embodiment, the rated supply voltage of the AC power grid is 380 V. Figure 1 The connection terminal to be connected to the AC power grid is denoted as 380 Vac.

[0040] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A back-to-back testing system for energy storage converters, characterized in that: The invention comprises a first energy storage converter (1), a second energy storage converter (2) and an isolation transformer (3); the DC end of the first energy storage converter (1) is connected to the DC end of the second energy storage converter (2); the AC end of the first energy storage converter (1) is connected to the primary side of the isolation transformer (3), and the AC end of the first energy storage converter (1) is connected in parallel to an AC power grid; and the AC end of the second energy storage converter (2) is connected to the secondary side of the isolation transformer (3).

2. The energy storage converter back-to-back testing system according to claim 1, characterized in that: The energy storage converter back-to-back test system further comprises a test terminal (4) and a switch (5); the test terminal (4) is electrically connected to the controlled end of the first energy storage converter (1) and the controlled end of the second energy storage converter (2) respectively through the switch (5).

3. The back-to-back testing system for energy storage converter according to claim 1, characterized in that: The rated AC power of the first energy storage converter (1) is 125 kW, the rated AC voltage is 380 V, and the DC voltage input range is 680-950 V.

4. The energy storage converter back-to-back testing system according to claim 1, characterized in that: The rated AC power of the second energy storage converter (2) is 125 kW, the rated AC voltage is 380 V, and the DC voltage input range is 680-950 V.

5. The energy storage converter back-to-back testing system according to claim 1, characterized in that: The rated capacity of the isolation transformer (3) is 150 kVA, the primary side voltage is 400 V, and the secondary side voltage is 400 V.

6. The energy storage converter back-to-back testing system according to claim 1, characterized in that: The operation mode of the first energy storage converter (1) is a constant DC voltage mode.

7. The energy storage converter back-to-back testing system according to claim 6, characterized in that: The constant DC voltage value of the first energy storage converter (1) is in the range of 680 to 950 V.

8. The energy storage converter back-to-back testing system according to claim 1, characterized in that: The operation mode of the second energy storage converter (2) is a constant power mode.

9. The energy storage converter back-to-back testing system according to claim 8, characterized in that: The power value of the second energy storage converter (2) is in the range of -125 to 125 kW.

10. The energy storage converter back-to-back testing system according to claim 1, characterized in that: The rated voltage of the AC power grid is 380V.

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