Power grid strength construction structure and device for new energy and energy storage grid-connected performance test

Abstract

The invention provides a power grid strength construction structure and device for a new energy and energy storage grid-connected performance test. The method is suitable for a new energy / energy storage power station. The method comprises the following steps: arranging a power grid strength construction unit among an energy storage converter, a transformer and a power grid, and configuring a new energy station grid-connected performance detection platform. The construction unit comprises a bypass, a branch 1 and a branch 2 which are all connected with a sampling point. The bypass is composed of bypass switches, the branch 1 comprises a multi-tap reactor and two selection switches, and the branch 2 comprises a multi-tap reactor and an input switch. The branch 1 and the branch 2 are connected with one end of the multi-tap reactor, and the bypass is connected with the other end of the multi-tap reactor. Impedance parameters of the power grid strength construction unit can be accurately adjusted by controlling on and off of each switch. According to the method, the construction units are arranged among the energy storage converter, the transformer and the power grid, and bypass and branch structures are configured, so that accurate construction and adjustment of the strength of the power grid are realized.

Description

Technical Field

[0001] The present application belongs to the field of power grid strength construction, and in particular, relates to a power grid strength construction structure and device for testing the performance of new energy and energy storage grid connection. Background Art

[0002] As the proportion of new energy and energy storage access continues to rise, the grid-connected performance test of new energy sites (such as wind farms, photovoltaic power stations) and energy storage power stations has become particularly important. In order to ensure the safe and stable operation of the power system, it is necessary to conduct comprehensive and accurate tests on the grid-connected performance of new energy sites and energy storage power stations. However, traditional grid-connected performance test methods often ignore the impact of grid strength on test results, resulting in a large deviation between the test results and actual operating conditions. Grid strength refers to the grid's ability to withstand and stability of fluctuations in the output power of new energy sites. It is directly related to the operating effect of new energy sites after grid connection and the overall stability of the grid. Summary of the invention

[0003] The purpose of this application is to overcome the defects existing in the above-mentioned prior art and to provide a grid strength construction structure and device for testing the performance of new energy and energy storage grid connection.

[0004] The present application provides a grid strength structure for testing the performance of new energy and energy storage grid connection, including:

[0005] A power grid strength construction unit is set between the energy storage converter and transformer of the new energy / energy storage power station and the power grid, and a new energy station grid connection performance detection platform is set between the power grid strength construction unit and the power grid;

[0006] The grid strength construction unit includes a bypass, and a branch 1 and a branch 2 connected in parallel; the bypass, branch 1 and branch 2 are connected to a sampling point; the bypass includes a bypass switch; the branch 1 includes a multi-tap reactor connected in series, a first selection switch and a second selection switch; the branch 2 includes a multi-tap reactor connected in series and a switch; the branch 1 and the branch 2 are connected to one end of the multi-tap reactor, and the bypass is connected to the other end of the multi-tap reactor;

[0007] The opening and closing of the bypass switch, the first selection switch, the second selection switch and the input switch are controlled to adjust the impedance parameters of the power grid strength construction unit.

[0008] Optionally, it also includes:

[0009] Set up three measurement points, including the remote measurement point, the near-end measurement point and the machine-end measurement point;

[0010] The remote metering point is located between the new energy station grid-connected performance detection platform and the grid strength construction unit;

[0011] The proximal measurement point is located on the high voltage side of the transformer;

[0012] The machine-end measurement point is located at the low-voltage side of the transformer.

[0013] Optionally, the grid strength construction unit, transformer and line are all resistive-inductive.

[0014] Optionally, the grid strength construction unit further includes a container and a cooling system, and control and protection equipment;

[0015] The control and protection equipment includes a controller, a power distribution, a sensor and a communication device.

[0016] Optionally, the grid strength construction unit equivalently simulates different short-circuit ratios, including: SCR40, SCR1.3 and SCR1.0.

[0017] The present application also provides a grid strength construction device for testing the performance of new energy and energy storage grid connection, including:

[0018] The connection end of the new energy / energy storage power station is connected to the energy storage converter of the new energy / energy storage power station through a transformer;

[0019] New energy station grid-connected performance testing platform connection terminal, used to connect to the new energy station grid-connected performance testing platform;

[0020] A power grid strength construction unit is arranged between the new energy station grid-connected performance detection platform and the transformer, and the power grid strength construction unit includes: a bypass, which includes a bypass switch for providing a direct connection path when no additional power grid strength construction is required; branch 1, which includes a multi-tap reactor connected in series, a first selection switch and a second selection switch, and the impedance value of branch 1 can be adjusted by selecting different taps and switch combinations; branch 2, which includes a multi-tap reactor connected in series and a switch, and the impedance value of branch 2 can be adjusted by selecting different taps and switch states; a multi-tap reactor, one end of which is connected to branch 1 and branch 2, and the other end is connected to the bypass, and the impedance characteristics of the entire power grid strength construction unit can be further adjusted by adjusting the tap position of the resistor;

[0021] The control unit is used to control the opening and closing states of the bypass switch, the first selection switch, the second selection switch and the input switch to adjust the impedance parameters of the power grid strength construction unit according to the test requirements, thereby realizing the construction and adjustment of the power grid strength.

[0022] Optionally, it also includes:

[0023] Set up three measurement points, including the remote measurement point, the near-end measurement point and the machine-end measurement point;

[0024] The remote metering point is located between the new energy station grid-connected performance detection platform and the grid strength construction unit;

[0025] The proximal measurement point is located on the high voltage side of the transformer;

[0026] The machine-end measurement point is located at the low-voltage side of the transformer.

[0027] Optionally, the grid strength construction unit, transformer and line are all resistive-inductive.

[0028] Optionally, the grid strength construction unit further includes a container and a cooling system, and control and protection equipment;

[0029] The control and protection equipment includes a controller, a power distribution, a sensor and a communication device.

[0030] Optionally, the grid strength construction unit equivalently simulates different short-circuit ratios, including: SCR40, SCR1.3 and SCR1.0.

[0031] The beneficial effects of this application are:

[0032] The present application provides a grid strength construction structure for testing the grid-connected performance of new energy and energy storage, including: a grid strength construction unit is set between the energy storage converter and transformer of the new energy / energy storage power station and the grid, and a new energy station grid-connected performance detection platform is set between the grid strength construction unit and the grid; the grid strength construction unit includes a bypass, and a branch 1 and a branch 2 connected in parallel; the bypass, branch 1 and branch 2 are connected to a sampling point; the bypass includes a bypass switch; the branch 1 includes a multi-tap reactor, a first selection switch and a second selection switch connected in series; the branch 2 includes a multi-tap reactor and a start-up switch connected in series; the branch 1 and the branch 2 are connected to one end of the multi-tap reactor, and the bypass is connected to the other end of the multi-tap reactor; the opening and closing of the bypass switch, the first selection switch, the second selection switch and the start-up switch are controlled to adjust the impedance parameters of the grid strength construction unit. This application achieves precise construction and adjustment of the grid strength by setting up a grid strength construction unit between the energy storage converter and transformer of the new energy / energy storage power station and the grid, and configuring structures such as bypass, branch 1 and branch 2. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the grid strength construction process for the new energy and energy storage grid connection performance test in this application;

[0034] Figure 2 This is a wiring diagram for the new energy and energy storage grid-connected performance test in this application;

[0035] Figure 3It is a schematic diagram of the internal structure of the power grid strength unit in this application;

[0036] Figure 4 It is a schematic diagram of the SCR theoretical analysis in this application;

[0037] Figures 5 to 10 It is a schematic diagram comparing the SCR theoretical analysis results and the measured results in this application. DETAILED DESCRIPTION

[0038] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that various forms of implementing the present disclosure should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0039] In the field of new energy and energy storage grid connection, especially in the grid connection performance test of grid-connected energy storage systems, the simulation and construction of grid strength is a crucial link.

[0040] Please refer to Figure 1 , Figure 2 and Figure 3 As shown, the present application provides a grid strength structure for testing the performance of new energy and energy storage grid connection, including:

[0041] S101. Set up a grid strength construction unit between the energy storage converter and transformer of the new energy / energy storage power station and the grid.

[0042] A new energy station grid-connected performance detection platform is set between the grid strength construction unit and the grid.

[0043] A grid strength construction unit is cleverly set up between the energy storage converter and transformer of the new energy / energy storage power station and the power grid. The design of this construction unit enables the grid strength of the grid connection point to be accurately adjusted and controlled, thereby providing a stable and controllable grid connection environment for the performance test of the grid-connected energy storage system.

[0044] Specifically, a new energy station grid-connected performance testing platform is set up between the grid strength construction unit and the grid. The main function of this platform is to simulate various working conditions such as voltage failure and frequency change. By cooperating with the grid strength construction unit, the adaptability of new energy and energy storage power stations under different grid strengths can be tested more accurately.

[0045] The grid strength construction unit includes a bypass, and a branch 1 and a branch 2 connected in parallel; the bypass, branch 1 and branch 2 are connected to a sampling point; the bypass includes a bypass switch; the branch 1 includes a multi-tap reactor connected in series, a first selection switch and a second selection switch; the branch 2 includes a multi-tap reactor connected in series and a switching-in switch; the branch 1 and the branch 2 are connected together to one end of the multi-tap reactor, and the bypass is connected to the other end of the multi-tap reactor.

[0046] The grid strength construction unit in this application is a key component, which is specially designed to simulate and construct grid environments of different strengths to meet the grid-connected performance test requirements of the grid-type energy storage system. The unit includes a bypass and parallel branches 1 and 2. This design enables the impedance parameters of the grid to be flexibly adjusted through different switch combinations.

[0047] The bypass consists of a bypass switch that can short-circuit the grid strength construction unit when necessary, thereby achieving rapid switching and regulation of the circuit.

[0048] Branch 1 includes a multi-tap reactor, which can change its inductance value by selecting different taps, thereby adjusting the impedance of the power grid. The first selection switch and the second selection switch are connected in series after the multi-tap reactor, and they work together to select a specific reactance value to achieve precise impedance adjustment.

[0049] Similar to branch 1, branch 2 also includes a multi-tap reactor for changing the inductance value. The input switch in branch 2 is used to control the connection and disconnection of the branch, thereby adjusting the impedance of the power grid as needed.

[0050] Branch 1 and branch 2 are connected to one end of the multi-tap reactor, while the bypass is connected to the other end of the multi-tap reactor. The design of the multi-tap reactor allows the impedance of the power grid to be further adjusted by changing the resistance value by selecting different taps.

[0051] In practical applications, the impedance parameters of the grid strength construction unit can be flexibly adjusted by controlling the different combinations of the bypass switch, the first selection switch, the second selection switch and the input switch. This adjustment method can change the impedance value from the inverter end to the grid, and then change the short-circuit ratio of the grid connection point, thereby creating a local weak grid or a local strong grid environment.

[0052] The new energy site grid-connected performance detection platform and the grid strength construction device are connected in series between the new energy / energy storage box transformer and the circuit breaker. A total of three metering points are set up. The remote metering point is located between the new energy site grid-connected performance detection platform and the grid strength construction device, the proximal measurement point is located on the high-voltage side of the box transformer, and the machine-end measurement point is located on the low-voltage side of the box transformer.

[0053] The new energy station grid-connected performance test platform and the following equipment are connected to the grid, which is equivalent to connecting to an infinite power source. Therefore, the short-circuit ratio of the grid-connected point of the tested equipment is:

[0054]

[0055] Among them, U is the rated line voltage of the equipment under test, P n is the rated capacity of the equipment under test, Z is the short-circuit impedance of the line from the power grid to the equipment under test, and the equipment is equivalent to the equipment under test, including the impedance of the new energy station grid-connected performance detection platform, the power grid strength construction device, the transformer and the line.

[0056] Furthermore, the output port of the new energy station grid-connected performance detection platform has a secondary voltage regulation function, which can ensure that the output voltage is not affected by power and line impedance, and can be equivalent to an ideal voltage source, so its short-circuit impedance is approximately 0.

[0057] Furthermore, the grid strength structure, transformer and line are all resistive and inductive, and X>>R, the resistance can be ignored, then

[0058]

[0059] X is the short-circuit reactance of the line from the grid-connected performance detection platform of the new energy station to the machine end of the equipment under test, and the equipment equivalent to the machine end of the equipment under test, including the reactance of the grid strength construction device, transformer and line.

[0060] Furthermore, for the grid strength construction device and transformer, the line reactance can be ignored, then

[0061]

[0062] Among them, X K , X T are the short-circuit reactance of the grid strength construction device and transformer, L K , L T They are the short-circuit inductance of the grid strength construction device and the transformer respectively.

[0063] Furthermore, the short-circuit reactance X T It can be calculated by referring to the following formula:

[0064]

[0065] Machine-end short-circuit impedance = machine-end rated impedance × short-circuit impedance coefficient

[0066] Machine end short circuit resistance 2 +Short-circuit reactance at the machine end 2 = Short-circuit impedance at the machine end 2

[0067]

[0068] For dry-type transformers, X / R is generally greater than or equal to 10, and 10 is used in this calculation.

[0069] Furthermore, by changing the inductive reactance of the grid strength construction device, the short-circuit ratio of the grid connection point of the device under test can be changed. Figure 2 As shown, it includes multi-tap reactors, multi-tap reactors, bypass switches, input switches, selector switches, flexible cables and accessories, containers and cooling systems, control and protection equipment (impedance setting, switching control functions, including controllers, power distribution, sensors, communication devices, etc.) and other accessories of test equipment (necessary components for connecting test equipment).

[0070] Control the switches CB1, CB2, KM1, and KM2 inside the grid strength construction device so that different reactance values ​​L are displayed externally at different working positions. K (When the resistance is negligible, the resistance in the device can be directly short-circuited), as shown in the following table:

[0071] Serial number Switch combination Inductance 1 CB1 is closed, CB2, KM1, and KM2 are open 0 2 KM2 is closed, CB1, CB2, KM1 are open 0.225H 3 KM1 is closed, CB1, CB2, KM2 are open 0.324H

[0072] Furthermore, the SCR theoretical analysis results can be verified. The principle is as follows: Figure 4 As shown in Figure 1, considering the resistance and inductance of the entire line, the current flowing through the entire line will generate power loss on the equivalent resistance and equivalent inductance, resulting in a difference between the active and reactive power at the remote end and the machine end. Therefore, the remote active power P can be collected under different power scheduling. G , reactive power Q G and the active power P at the machine end PCS , reactive power Q PCS , apparent current I S , and according to the power flow distribution formula shown below, the equivalent short-circuit resistance and short-circuit inductive reactance of the machine-side system can be calculated.

[0073] Definition I S =I p +jI q , then:

[0074] ΔP=P PCS -P G =(I p 2 +I q 2 )R=|I S | 2 R

[0075] ΔQ=Q PCS -Q G=(I p 2 +I q 2 )X=|I S | 2 X

[0076] S102, controlling the opening and closing of the bypass switch, the first selection switch, the second selection switch and the input switch to adjust the impedance parameters of the grid strength construction unit.

[0077] Specifically, the impedance parameter target value that the grid strength construction unit needs to achieve is clarified. According to the adjustment target, the circuit path and impedance element of the grid strength construction unit are changed by controlling the opening and closing states of the bypass switch, the first selection switch, the second selection switch and the input switch.

[0078] During the adjustment process, the impedance parameters of the grid strength construction unit are monitored in real time to ensure that they reach the target value. If necessary, the switch state can be further adjusted until the requirements are met.

[0079] Finally, the adjusted grid strength construction unit is put into operation.

[0080] The present application changes the impedance parameters of the grid strength construction device by controlling the internal switch combination. Specifically, the device contains multiple controllable switches, and through different switch combinations, the impedance value of the device can be flexibly adjusted, thereby further changing the short circuit ratio (SCR) of the machine end of the grid-type energy storage system equipment.

[0081] The short-circuit ratio is an important indicator for measuring the strength of the power grid, which reflects the grid's ability to support grid-connected equipment. By adjusting the short-circuit ratio, grid environments of different strengths can be simulated, providing a rich test scenario for the performance test of the grid-connected energy storage system.

[0082] The present application provides a power grid strength construction unit. The unit integrates multiple controllable switches and impedance elements. By accurately controlling the opening and closing states of the switches, the impedance parameters of the device can be flexibly adjusted. In addition, the device also has real-time monitoring and feedback functions, which can monitor various parameters in the power grid strength construction process in real time to ensure the accuracy and reliability of the test results.

[0083] The grid strength construction device designed in this application is combined with the new energy station grid connection performance detection platform to successfully complete the performance test of the grid-connected energy storage system under different grid strengths such as SCR40, SCR1.3 and SCR1.0. The test results show that the grid-connected energy storage system exhibits good frequency and voltage regulation performance under both strong and weak grids, verifying its adaptability and stability under different grid environments.

[0084] The proposal and application of this application provide a more realistic and comprehensive testing environment for the performance testing of power electronic grid-connected equipment such as new energy and energy storage. By simulating power grid environments of different intensities, the performance of the grid-type energy storage system under different power grid conditions can be more accurately evaluated, providing strong technical support for its application in actual power systems. At the same time, the power grid strength construction method and device of the present invention also lay a solid foundation for the application of new energy and energy storage equipment in different power grid environments, and help promote the further development and application of new energy and energy storage technologies.

[0085] The present application also provides a grid strength construction device for testing the performance of new energy and energy storage grid connection, including:

[0086] The connection end of the new energy / energy storage power station is connected to the energy storage converter of the new energy / energy storage power station through a transformer;

[0087] New energy station grid-connected performance testing platform connection terminal, used to connect to the new energy station grid-connected performance testing platform;

[0088] A power grid strength construction unit is arranged between the new energy station grid-connected performance detection platform and the transformer, and the power grid strength construction unit includes: a bypass, which includes a bypass switch for providing a direct connection path when no additional power grid strength construction is required; branch 1, which includes a multi-tap reactor connected in series, a first selection switch and a second selection switch, and the impedance value of branch 1 can be adjusted by selecting different taps and switch combinations; branch 2, which includes a multi-tap reactor connected in series and a switch, and the impedance value of branch 2 can be adjusted by selecting different taps and switch states; a multi-tap reactor, one end of which is connected to branch 1 and branch 2, and the other end is connected to the bypass, and the impedance characteristics of the entire power grid strength construction unit can be further adjusted by adjusting the tap position of the resistor;

[0089] The control unit is used to control the opening and closing states of the bypass switch, the first selection switch, the second selection switch and the input switch to adjust the impedance parameters of the power grid strength construction unit according to the test requirements, thereby realizing the construction and adjustment of the power grid strength.

[0090] Furthermore, it also includes:

[0091] Set up three measurement points, including the remote measurement point, the near-end measurement point and the machine-end measurement point;

[0092] The remote metering point is located between the new energy station grid-connected performance detection platform and the grid strength construction unit;

[0093] The proximal measurement point is located on the high voltage side of the transformer;

[0094] The machine-end measurement point is located at the low-voltage side of the transformer.

[0095] Furthermore, the grid strength construction unit, transformer and line are all resistive and inductive.

[0096] Furthermore, the grid strength construction unit also includes a container and a cooling system, and control and protection equipment;

[0097] The control and protection equipment includes a controller, a power distribution, a sensor and a communication device.

[0098] Furthermore, the grid strength construction unit equivalently simulates different short-circuit ratios, including: SCR40, SCR1.3 and SCR1.0.

[0099] Specific applications:

[0100] The on-site transformer parameters are as follows:

[0101] Parameter Type Numeric unit Transformer capacity 3150 kVA Rated line voltage at the machine end 800 V Short circuit impedance coefficient 8.3 ％ Transformer X / R 10 /

[0102] The calculated parameters are as follows:

[0103] Parameter Type Numeric unit Rated impedance of machine end 0.203 Ω Machine end short circuit impedance 0.017 Ω Machine end short circuit resistance 0.002 Ω Machine end short circuit reactance 0.017 Ω Machine-end equivalent inductance 0.053 mh

[0104] The three inductance levels of the grid strength construction device are 0, 0.225H, and 0.342H to simulate SCR40, SCR1.3, and SCR1.0. According to the actual factory data of the three-phase inductance provided by the equipment manufacturer, the actual inductance values ​​of the three inductance levels of the grid strength construction device are 0, 0.2301H, and 0.3494H, respectively. After the box transformer is converted to the equivalent inductance values ​​of the machine end, they are 0, 1.4726mH, and 2.2362mH, respectively.

[0105] According to the rated capacity P of the energy storage system n =1MW, rated voltage U = 800V, and the inductance of the grid strength structure device and transformer, according to the SCR calculation formula:

[0106]

[0107] From the above table, we can see that when SCR1.0 is in gear, according to the rated capacity P of the energy storage system n =1MW calculation, the theoretical SCR is only 0.890, which exceeds the physical limit, so it needs to be re-adjusted. The results are as follows:

[0108]

[0109] Furthermore, the SCR theoretical analysis results were verified, and the grid strength construction device was adjusted to SCR 40 (CB1 closed, CB2, KM1, KM2 open), SCR1.3 (KM2 closed, CB1, CB2, KM1 open), and SCR1.0 (KM1 closed, CB1, CB2, KM2 open). Power was dispatched from light load to full load according to a certain gradient, and statistics were collected on the active, reactive, and current data at the machine and remote ends, and the SCR verification algorithm was used for calculation.

[0110] The actual measured resistance is much smaller than the inductance and can be ignored. The average full-load equivalent inductance of the machine end measured by this method under SCR40, SCR1.3, and SCR1.0 are 0.054mH, 1.498mH, and 2.258mH respectively, and the corresponding SCR calculated values ​​are 37.726, 1.360, and 1.002 respectively.

[0111]

[0112] Please refer to Figures 5 to 10 As shown, by comparing the SCR theoretical analysis results and the measured results, the SCR calibration progress reaches more than 98%, meeting the general test conditions.

[0113] The above are only specific embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A grid strength structure for testing the performance of new energy and energy storage grid connection, characterized in that: include: A power grid strength construction unit is set between the energy storage converter and transformer of the new energy / energy storage power station and the power grid, and a new energy station grid connection performance detection platform is set between the power grid strength construction unit and the power grid; The grid strength construction unit includes a bypass, and a branch 1 and a branch 2 connected in parallel; The bypass, branch 1 and branch 2 are connected to the sampling point; The bypass includes a bypass switch; the branch 1 includes a multi-tap reactor connected in series, a first selection switch and a second selection switch; the branch 2 includes a multi-tap reactor connected in series and a switch; the branch 1 and the branch 2 are connected to one end of the multi-tap reactor, and the bypass is connected to the other end of the multi-tap reactor; The opening and closing of the bypass switch, the first selection switch, the second selection switch and the input switch are controlled to adjust the impedance parameters of the power grid strength construction unit.

2. According to claim 1, a grid strength structure for testing the performance of new energy and energy storage grid connection, characterized in that: Also includes: Set up three measurement points, including the remote measurement point, the near-end measurement point and the machine-end measurement point; The remote metering point is located between the new energy station grid-connected performance detection platform and the grid strength construction unit; The proximal measurement point is located on the high voltage side of the transformer; The machine-end measurement point is located at the low-voltage side of the transformer.

3. According to claim 1, a grid strength structure for testing the performance of new energy and energy storage grid connection, characterized in that: The grid strength construction unit, transformer and each connecting line are all resistive-inductive.

4. The grid strength structure for testing the performance of new energy and energy storage grid connection according to claim 1, characterized in that: The grid strength construction unit also includes a container and a cooling system, and control and protection equipment; The control and protection equipment includes a controller, a power distribution, a sensor and a communication device.

5. The grid strength structure for testing the performance of new energy and energy storage grid connection according to claim 1, characterized in that: The grid strength construction unit equivalently simulates different short circuit ratios, including: SCR40, SCR1.3 and SCR1.

0.

6. A grid strength construction device for testing the performance of new energy and energy storage grid connection, characterized in that: include: A new energy / energy storage power station connection terminal, used to connect to the energy storage converter of the new energy / energy storage power station through a transformer; New energy station grid-connected performance testing platform connection terminal, used to connect to the new energy station grid-connected performance testing platform; A power grid strength construction unit is used to be arranged between a new energy station grid-connected performance detection platform and a transformer, and the power grid strength construction unit includes: a bypass, which includes a bypass switch, which is used to provide a direct connection path when no additional power grid strength construction is required; branch 1, which includes a multi-tap reactor connected in series, a first selection switch and a second selection switch, and the impedance value of branch 1 can be adjusted by selecting different taps and switch combinations; branch 2, which includes a multi-tap reactor connected in series and a switch, and the impedance value of branch 2 can be adjusted by selecting different taps and switch states; a multi-tap reactor, one end of which is connected to branch 1 and branch 2, and the other end is connected to the bypass, and the impedance characteristics of the entire power grid strength construction unit can be further adjusted by adjusting the tap position of the resistor; The control unit is used to control the opening and closing states of the bypass switch, the first selection switch, the second selection switch and the input switch to adjust the impedance parameters of the power grid strength construction unit according to the test requirements, thereby realizing the construction and adjustment of the power grid strength.

7. A grid strength construction device for testing the performance of new energy and energy storage grid connection according to claim 6, characterized in that: Also includes: Set up three measurement points, including the remote measurement point, the near-end measurement point and the machine-end measurement point; The remote metering point is located between the new energy station grid-connected performance detection platform and the grid strength construction unit; The proximal measurement point is located on the high voltage side of the transformer; The machine-end measurement point is located at the low-voltage side of the transformer.

8. A grid strength construction device for testing the performance of new energy and energy storage grid connection according to claim 6, characterized in that: The grid strength construction unit, transformer and each connecting line are all resistive-inductive.

9. A grid strength construction device for testing the performance of new energy and energy storage grid connection according to claim 6, characterized in that: The grid strength construction unit also includes a container and a cooling system, and control and protection equipment; The control and protection equipment includes a controller, a power distribution, a sensor and a communication device.

10. A grid strength construction device for testing the performance of new energy and energy storage grid connection according to claim 6, characterized in that: The grid strength construction unit equivalently simulates different short circuit ratios, including: SCR40, SCR1.3 and SCR1.0.

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