Direct-current power grid short-circuit protection matching test system and method
By constructing a short-circuit current generating device for battery packs and generator sets, and simulating real current characteristics, the problem of verification distortion caused by differences in current characteristics in traditional test methods is solved, and high-precision DC grid short-circuit protection matching test is achieved.
Patent Information
- Application Number
- CN202511967596.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-02-13
AI Technical Summary
Traditional DC grid short-circuit protection matching test methods cannot accurately simulate the short-circuit current characteristics of battery banks and generator sets, leading to distorted verification conclusions.
A short-circuit current generating device for a battery pack and a short-circuit current generating device for a generator set were constructed. The 'AC impulse source + controllable rectification' and 'capacitor energy storage + resonant modulation' technologies were respectively used to simulate the first-order short-circuit current of the battery pack and the oscillation decline characteristics of the generator set. The current signals were collected and transmitted through a measurement system to achieve high-precision superposition of the current waveforms.
It enables high-confidence assessment of the graded protection performance of DC circuit breakers, ensuring that the test current is consistent with the actual current characteristics, shortening the commissioning cycle and reducing risks.
Smart Images
Figure CN121522332A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the electrical field, especially to a DC power grid short-circuit protection matching test system and method. BACKGROUND
[0002] The ship DC power grid generally uses generator set and battery set to supply power to the main and auxiliary machines of the whole ship, and the DC power grid generally sets two or three circuit breakers to protect various different short-circuit conditions, and the circuit breakers at different levels are required to have grading protection characteristics. In order to verify the grading protection characteristics between the circuit breakers, the circuit breakers need to be connected according to the power grid connection mode and input a prospective short-circuit current similar to the actual short-circuit current characteristic.
[0003] In the traditional DC power grid short-circuit protection matching test method, when simulating the prospective short-circuit current of multiple power sources, the peak value of the short-circuit current formed by the superposition of the short-circuit currents between multiple power sources is generally directly calculated, and then a prospective short-circuit current with a first-order characteristic is generated in combination with the time constant of a certain power source. However, in fact, the short-circuit current of the battery set is generally a first-order characteristic, and the short-circuit current of the generator set is generally an oscillating descending characteristic. There is a large difference between the prospective short-circuit current formed by the traditional simulation method and the actual short-circuit current. When verifying the grading protection matching characteristics of the DC power grid designed according to the current principle, the difference in the short-circuit current will lead to distorted verification conclusions.
[0004] Therefore, it is necessary to design a battery set short-circuit current generating device, a generator set short-circuit current generating device, and input the above-mentioned currents into the circuit breaker to be tested after superposition according to the actual situation, verify the grading protection performance of the circuit breaker, and thus more truly verify the grading protection matching characteristics of the system and verify the DC power grid short-circuit protection matching based on the current principle. The test prospective short-circuit current needs to be consistent with the short-circuit current characteristic of the actual power source as much as possible, and therefore it is necessary to construct a related test method and test circuit to solve the problem. SUMMARY
[0005] The technical problem to be solved by the present application is to provide a DC power grid short-circuit protection matching test system and method in view of the defects in the prior art.
[0006] The technical scheme adopted by the present application to solve the technical problem is: The present application provides a DC power grid short-circuit protection matching test system, comprising: a battery set short-circuit current generating device, a generator set short-circuit current generating device, and a measurement system; wherein: The battery pack short-circuit current generating device adopts a double-stage structure of 'AC impulse source + controllable rectification', wherein a three-phase AC impulse generator provides transient current through transient acceleration of a rotor; a plurality of current limiting units are arranged, AC side parallel current limiting resistors and reactors are arranged, and adjustable resistors and waveform shaping reactors are arranged on the DC side; a multi-phase bridge rectifier circuit is adopted for the rectification system to realize control of the output ripple coefficient; The generator set short-circuit current generating device is used for constructing a 'capacitor energy storage + resonance modulation' simulation system, wherein a large-capacity capacitor group is arranged to support multi-gear voltage switching; a dynamic resonance circuit containing a variable reactor and a resistor is designed to simulate different time constants; and resonance modulation technology is applied to make the short-circuit current waveform simulate the typical oscillation and attenuation characteristics of a generator. In the measurement system, a shunt is used for DC side current sampling, and a pure resistor voltage divider is used for measuring positive and negative electrode voltages; measurement output signals are converted by an optical isolation converter and then transmitted to a data acquisition instrument by an optical fiber.
[0007] Further, the specific circuit structure of the battery pack short-circuit current generating device of the present application comprises a generator, a rectification system, a test transformer, an adjusting resistor, an adjusting reactor, a shunt, a phase separation and closing circuit breaker, a first operation circuit breaker, a protection circuit breaker, and is electrically connected in the following manner: The generator adopts a three-phase AC impulse generator; the output end of the generator is connected with the primary winding of the test transformer after sequentially passing through the phase separation and closing circuit breaker, the first operation circuit breaker, the adjusting resistor, the adjusting reactor and the protection circuit breaker in series. One end of the secondary side of the test transformer is connected to the first end of the test and comparison product circuit breaker after passing through the rectification system and the shunt; the other end of the secondary side is connected to the test product after passing through the rectification system, and the second end of the test and comparison product circuit breaker is also connected to the test product.
[0008] Further, the specific circuit structure of the battery pack short-circuit current generating device of the present application further comprises a second operation circuit breaker; the first operation circuit breaker and the adjusting resistor are grounded through the second operation circuit breaker and a fixed resistor.
[0009] Further, the specific circuit structure of the battery pack short-circuit current generating device of the present application further comprises a grounding resistor; the generator is grounded through the grounding resistor.
[0010] Further, the specific circuit structure of the generator set short-circuit current generating device of the present application comprises a DC power supply, a current limiting resistor, a wave modulation reactor, a capacitor group, a wave modulation resistor, a waveform sampling system and a control system, and is electrically connected in the following order: The positive pole of the direct current power supply is connected to the positive end of the capacitor group through the current limiting resistor, and the negative pole is directly connected to the negative end of the capacitor group, forming a controllable charging circuit; The positive and negative ends of the capacitor group are connected in parallel with a resonant modulation branch composed of the wave modulation reactor and the wave modulation resistor in series, for generating an oscillation-attenuated short-circuit current waveform in the discharge stage; the waveform sampling system is connected across the resonant modulation branch, and real-time current / voltage signals are collected and sent to the control system.
[0011] Further, the measurement sensor used by the test system comprises a voltage sensor, a current sensor, a shunt, and a pure resistance voltage divider, and the output signals of the measurement sensor are transmitted to the data acquisition instrument by optical fiber after optical isolation conversion.
[0012] Further, the connection circuit of the battery pack short-circuit current generating device and the generator set short-circuit current generating device is provided with a test sample breaker, a first vacuum breaker, a bus tie switch, a shunt I system, a shunt IC, and a shunt I total, and is electrically connected in the following manner: The positive and negative output ends of the battery pack short-circuit current generating device are connected to the corresponding positive and negative common buses through the test sample breaker; the positive and negative output ends of the generator set short-circuit current generating device are connected to the same positive and negative common buses through the first vacuum breaker, realizing parallel connection with the battery circuit; the bus tie switch is connected across the positive and negative common buses and used as a short-circuit switch to form a short-circuit test point; The shunt I system is connected in series in the positive pole circuit of the battery pack short-circuit current generating device and used for independently collecting the current waveform thereof; the shunt IC is connected in series in the positive pole circuit of the generator set short-circuit current generating device and used for independently collecting the current waveform thereof; and the shunt I total is connected in series in the positive common bus and used for collecting the total short-circuit current waveform after superposition of the two devices; By closing the test sample breaker and the first vacuum breaker in time sharing or simultaneously, and then closing the bus tie switch, the superimposed waveform of the two current waveforms can be obtained at the short-circuit test point, so as to verify whether the expected waveform meets the requirements.
[0013] The application provides a DC power grid short-circuit protection matching test method, which comprises the following steps: Step 1, parameter pre-calculation: for the battery pack short-circuit current generating device, the direct current side inductance Lt and the resistance Rt to be input are calculated according to Ohm's law and the time constant formula; for the generator set short-circuit current generating device, the resistance, the capacitance C2 and the inductance L2 to be input are calculated according to the target open circuit voltage, the short-circuit current peak value and the time required for the current to rise to the peak value; Step 2, battery loop pre-adjustment: gradually increase the generator output voltage until the DC port voltage reaches the target open circuit voltage, otherwise continue to fine-tune until it meets the requirements; Step 3, battery loop waveform fine adjustment: close the test breaker to short the DC port, and use timing control to determine the duration of the short circuit; collect the shunt I current waveform, if the current value or time constant deviates from the target, return to step 1 and fine-tune Lt and Rt until the waveform meets the target requirements; Step 4, generator set loop pre-adjustment: open the generator loop switch and close the charging loop switch, gradually increase the high-power DC power supply from zero voltage to the target open circuit voltage, then open the charging switch and immediately close the short circuit switch to complete the discharge; collect the shunt IC current waveform, if the peak arrival time deviates from the target, return to step 1 and fine-tune C2 or L2 until the waveform meets the target requirements; Step 5, superimposed waveform verification: connect the battery pack short circuit current generating device through the test breaker and the generator set short circuit current generating device through the first vacuum breaker, then connect the two positive and negative poles in parallel, and close the bus tie switch to form a short circuit test point; simultaneously or at different times, close the test breaker and the first vacuum breaker, and use the shunt I to collect the total current waveform; if the superimposed peak or time parameter deviates from the expected value, repeat steps 3 and / or 4 to fine-tune Lt, Rt, C2, L2 until the synthesized waveform meets the test requirements.
[0014] Further, the fine-tuning of steps 3 and 4 of the present application is achieved by returning to step 1 to recalculate and adjust Lt, Rt, C2, L2 until the waveform meets the target requirements.
[0015] Further, step 5 of the present application is achieved by closing the test breaker and the first vacuum breaker at different times or simultaneously, and then using the bus tie switch to form a short circuit test point to collect the synthesized waveform after superimposing the two current waveforms.
[0016] The present application has the following advantages: (1) By constructing a battery pack short circuit current generating device, the first-order short circuit current characteristics of the battery pack are simulated, ensuring the equivalence and credibility of the expected short circuit current component provided by the battery pack.
[0017] (2) By constructing a generator set short circuit current generating device, the short circuit current characteristics of the generator oscillation are simulated, and the transient and decay components are completely reproduced, providing a high confidence breaking test environment for the grading protection test of the DC circuit breaker.
[0018] (3) Through the proposed parameter debugging method, two source parameters are independently fine-tuned, then are superimposed in parallel, and are closed-loop corrected, high-precision coincidence of the test current waveform and the expected waveform is realized, the synthesized wave conforms to the requirements of standards on shape, peak value and time constant, the debugging period is shortened and the test risk is reduced. BRIEF DESCRIPTION OF DRAWINGS
[0019] The application will be further described below in combination with the drawings and examples, in which: Figure 1 is a short-circuit current generating device principle diagram of a battery pack of an embodiment of the application.
[0020] Figure 2 is a short-circuit current generating device principle diagram of a generator set of an embodiment of the application.
[0021] Figure 3 is a short-circuit protection matching test system principle diagram of a DC power grid of an embodiment of the application. DETAILED DESCRIPTION
[0022] In order to make the purpose, technical scheme and advantages of the application more clear and understandable, the application will be further described in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application and not to limit the application.
[0023] Example 1 The application is composed of a battery pack short-circuit current generating device, a generator set short-circuit current generating device and a measurement system.
[0024] The battery pack short-circuit current generating device adopts a double-stage structure of "AC impulse source + controllable rectification", mainly composed of an AC impulse generator, an AC side current-limiting resistor, an AC side current-limiting reactor, a rectifier transformer, an uncontrollable rectification cabinet, a DC side current-limiting resistor, a DC side wave-shaping reactor, an auxiliary test switch, a waveform sampling system, a control system and the like. The three-phase AC impulse generator provides transient current through rotor instantaneous acceleration; a plurality of current-limiting units are arranged, the AC side is connected in parallel with the current-limiting resistor and the reactor, and the DC side is configured with the adjustable resistor and the wave-shaping reactor; a multi-phase bridge rectification circuit is adopted.
[0025] The generator set short-circuit current generating device constructs a "capacitor energy storage + resonance modulation" simulation system, mainly composed of a large-power DC power supply (for charging the main capacitor), a main capacitor bank, a charging current-limiting resistor, a wave-shaping resistor, a wave-shaping reactor, a waveform sampling system, a control system and the like. A large-capacity capacitor bank is arranged to support multi-gear voltage switching; a dynamic resonance circuit is designed, including a variable reactor and a resistor, for simulating different time constants; resonance modulation technology is applied to make the short-circuit current waveform simulate the typical oscillation decay characteristics of the generator.
[0026] The measurement system mainly consists of voltage sensors and current sensors. A shunt is used for sampling the DC short-circuit side current, and a pure resistive voltage divider is used for measuring the positive and negative voltages. The output signals of the measurement sensors are converted by optical isolation and then transmitted to the data acquisition instrument via optical fiber.
[0027] Example 2 Based on Embodiment 1, this invention provides a specific circuit structure, as follows: The DC power grid short-circuit protection matching test system of this invention includes: a battery bank short-circuit current generator, a generator set short-circuit current generator, and a measurement system; wherein: The battery pack short-circuit current generating device adopts a two-stage structure of "AC impulse source + controllable rectification". The three-phase AC impulse generator provides transient current through instantaneous rotor acceleration. Multi-stage current limiting units are set up, with current limiting resistors and reactors connected in parallel on the AC side and adjustable resistors and waveform shaping reactors configured on the DC side. The rectification system adopts a multi-phase bridge rectifier circuit to achieve control of the output ripple coefficient. The generator set short-circuit current generating device is used to construct a "capacitor energy storage + resonant modulation" simulation system. In this system, a large-capacity capacitor bank is set up to support multi-level voltage switching; a dynamic resonant circuit is designed, including a variable reactor and a resistor, to simulate different time constants; and resonant modulation technology is applied to enable the short-circuit current waveform to simulate the typical oscillation decay characteristics of a generator. The measurement system uses a shunt to sample the DC current and a pure resistance voltage divider to measure the positive and negative voltages. The measurement output signal is transmitted to the data acquisition instrument via optical fiber after being converted by an optical isolation converter.
[0028] like Figure 1 As shown, in a preferred embodiment of the present invention, the specific circuit structure of the battery pack short-circuit current generating device includes: a generator G, a rectifier system, a test transformer, an adjusting resistor Rt, an adjusting reactance Lt, a shunt, a phase-by-phase closing circuit breaker HK1, a first operating circuit breaker CD1, and a protection circuit breaker BD1, and are electrically connected in the following manner: The generator G is a three-phase AC impulse generator; the output terminal of the generator G is connected to the primary winding of the test transformer after passing through the phase-closing circuit breaker HK1, the first operating circuit breaker CD1, the regulating resistor Rt, the regulating reactance Lt, and the protection circuit breaker BD1 in series. One end of the secondary side of the test transformer is connected to the first terminal of the test circuit breaker QF1 after passing through the rectifier system and shunt; the other end of the secondary side is connected to the test specimen SP after passing through the rectifier system, and the second terminal of the test circuit breaker QF1 is also connected to the test specimen SP.
[0029] The first operating circuit breaker CD1 and the regulating resistor Rt are grounded through the second operating circuit breaker CD2 and the fixed resistor. The generator G is grounded through the grounding resistor Rjd.
[0030] like Figure 2 As shown, in a preferred embodiment of the present invention, the specific circuit structure of the generator set short-circuit current generating device includes: a DC power supply, a current-limiting resistor, a tuning reactor L2, a capacitor bank C2, a tuning resistor, a waveform sampling system, and a control system, which are electrically connected in the following order: The positive terminal of the DC power supply is connected to the positive terminal of the capacitor bank C2 after passing through the current limiting resistor, and the negative terminal is directly connected to the negative terminal of the capacitor bank, forming a controllable charging circuit. The positive and negative terminals of the capacitor bank C2 are connected in parallel to a resonant modulation branch consisting of the tuning reactor L2 and the tuning resistor connected in series, which is used to generate a short-circuit current waveform with oscillation attenuation during the discharge phase; the waveform sampling system is connected across the two ends of the resonant modulation branch to collect current / voltage signals in real time and send them to the control system.
[0031] The measurement sensors used in the test system include: voltage sensors, current sensors, shunts, and pure resistance voltage dividers. The output signals of the measurement sensors are converted by optical isolation and then transmitted to the data acquisition instrument via optical fiber.
[0032] like Figure 3 As shown, in a preferred embodiment of the present invention, the connection circuit between the battery pack short-circuit current generating device and the generator set short-circuit current generating device includes: a test circuit breaker QF1, a first vacuum circuit breaker QF3, a bus tie switch, a shunt I system, a shunt IC, and a shunt I assembly, and is electrically connected in the following manner: The positive and negative output terminals of the battery pack short-circuit current generating device are respectively connected to the positive and negative common bus after passing through the test circuit breaker QF1; the positive and negative output terminals of the generator set short-circuit current generating device are respectively connected to the same positive and negative common bus after passing through the first vacuum circuit breaker QF3, thus achieving parallel connection with the battery circuit; the bus tie switch is connected across the positive and negative common bus and serves as a short-circuit switch, forming a short-circuit test point; The shunt I is connected in series in the positive circuit of the battery pack short-circuit current generator to independently collect its current waveform; the shunt IC is connected in series in the positive circuit of the generator set short-circuit current generator to independently collect its current waveform; the shunt I is always connected in series on the positive common bus to collect the total short-circuit current waveform after the two devices are superimposed. By closing the test circuit breaker QF1 and the first vacuum circuit breaker QF3 at different times or simultaneously, and then closing the bus tie switch, a composite waveform of the two current waveforms superimposed can be obtained at the short-circuit test point to verify whether the expected waveform meets the requirements.
[0033] Example 3: Experimental Method Example Based on Examples 1 and 2, this embodiment of the invention provides a method for testing the matching performance of DC power grid short-circuit protection, which includes the following steps: Step 1, Parameter Pre-calculation: For the battery pack short-circuit current generator, calculate the required DC-side inductor Lt and resistor Rt based on Ohm's law and the time constant formula; For the generator set short-circuit current generator, calculate the required resistor, capacitor C2, and inductor L2 based on the target open-circuit voltage, short-circuit current peak value, and the time required for the current to rise to the peak value. Step 2, Battery circuit pre-adjustment: With the test circuit breaker QF1 in the open state, gradually increase the generator output voltage until the DC port voltage reaches the target open circuit voltage; otherwise, continue fine-tuning until the target is met. Step 3: Fine-tuning the battery circuit waveform: Close the test circuit breaker QF1 to short-circuit the DC port, and use timing control to control the duration of the short circuit; collect the current waveform of the shunt I series. If the current value or time constant deviates from the target, return to step 1 and fine-tune Lt and Rt until the waveform meets the target requirements. Step 4: Generator circuit pre-adjustment: Disconnect the discharge circuit switch and close the charging circuit switch. Gradually increase the high-power DC power supply from zero voltage to the target open circuit voltage. After the capacitor voltage stabilizes, disconnect the charging switch and immediately close the short-circuit switch to complete the discharge. Collect the current waveform of the shunt IC. If the peak arrival time deviates from the target, return to step 1 and fine-tune C2 or L2 until the waveform meets the target requirements. Step 5, Waveform Verification: Connect the battery pack short-circuit current generator to the test circuit breaker QF1 and the generator set short-circuit current generator to the first vacuum circuit breaker QF3. Connect the two positive and two negative terminals in parallel, and then close the bus tie switch to form a short-circuit test point. Simultaneously or time-sharingly close the test circuit breaker QF1 and the first vacuum circuit breaker QF3, and use shunt I to collect the composite current waveform. If the superimposed peak value or time parameters deviate from the expectation, repeat steps 3 and / or 4, and fine-tune Lt, Rt, C2, and L2 until the composite waveform meets the test requirements.
[0034] Example 4: Based on Example 3, this embodiment of the invention provides specific experimental parameters.
[0035] The following parameters serve as examples to illustrate the configuration and debugging methods of the test system: Battery pack short-circuit current parameters: open circuit voltage DC560V, 35kA, time constant 3ms; generator set short-circuit current parameters: open circuit voltage DC560V, peak short-circuit current 17.1kA, time from initial moment to peak current 2ms.
[0036] like Figure 1 As shown, the inductance value of the DC side is calculated to be 48μH and the resistance value to be 16mΩ according to Ohm's law and the time constant formula. After separating the test sample at the DC short-circuit port, first measure whether the voltage across the port meets the requirements (the DC port voltage can be controlled by adjusting the generator's output voltage) until the voltage meets the DC560V requirement. Use a timing control method to close the test sample at the DC port and open the circuit breaker on the AC side to control the duration of the short-circuit current. Check the current waveform acquired by the measurement system to see if the current value and time constant meet the requirements. If not, adjust the inductor Lt and the resistor Rt.
[0037] Figure 2 In the test, the target resistance value of 8 mΩ is calculated based on the open-circuit voltage and short-circuit current peak values required by the test. Then, the existing resistance of the test circuit is measured using a DC resistance tester to obtain the required resistance value R2. Based on the current peak time, the required inductance value of 35 μH and the capacitance value of C2 (56 mF) are calculated. Then, the existing inductance of the circuit is measured using an LRC inductance tester to obtain the required inductance value L2. The grounding switch or grounding wire on the capacitor bank is disconnected, the discharge circuit switch is opened, and the charging circuit switch is closed. The high-power DC power supply is turned on, and the voltage is gradually adjusted from 0V to DC 560V. After the voltage stabilizes, the charging switch is opened, and the discharge circuit is completed by closing the short-circuit switch through timing control. The test system is started, the short-circuit waveform is recorded, and the parameters are checked. If the time for the current to reach the peak current from the initial moment is long, the capacitance or inductance is reduced; if the time for the current to reach the peak current from the initial moment is short, the capacitance or inductance is increased, until the waveform meets the requirements.
[0038] Figure 3 In the middle, Figure 1 The battery pack short-circuit current generator shown Figure 2 The output terminals of the generator set short-circuit current generator shown are connected in parallel and short-circuited after passing through a vacuum circuit breaker. The test is conducted to verify whether the expected waveform of the two current waveforms superimposed together meets the requirements.
[0039] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.
[0040] It is to be understood that all such modifications and variations that can occur to those skilled in the art in the light of the foregoing description are to be considered within the scope of the application as defined in the claims appended hereto.
Claims
1. A direct current grid short circuit protection matching test system, characterized by, The application relates to a battery pack short-circuit current generating device, a generator set short-circuit current generating device and a measuring system. The battery pack short-circuit current generating device adopts a double-stage structure of "AC impulse source + controllable rectification", wherein a three-phase AC impulse generator provides transient current through rotor transient acceleration; a plurality of current limiting units are arranged, AC side parallel current limiting resistors and reactors are arranged, and adjustable resistors and waveform shaping reactors are arranged on the DC side; and a three-phase bridge rectifier circuit is adopted for the rectification system. The generator set short-circuit current generating device is used for constructing a "capacitor energy storage + resonance modulation" simulation system, wherein a large-capacity capacitor group is arranged to support multi-gear voltage switching; a dynamic resonance circuit containing a variable reactor and a resistor is designed to simulate different time constants; and resonance modulation technology is applied to make the short-circuit current waveform simulate the typical oscillation and attenuation characteristics of a generator. The measuring system adopts a shunt for DC side current sampling, a pure resistor voltage divider for positive and negative electrode voltage measurement, and optical isolation conversion for measurement output signals, which are transmitted to a data acquisition instrument through optical fibers. The specific circuit structure of the battery pack short-circuit current generating device comprises a generator (G), a rectification system, a test transformer, an adjusting resistor (Rt), an adjusting reactor (Lt), a shunt, a phase separation and closing circuit breaker (HK1), a first operation circuit breaker (CD1) and a protection circuit breaker (BD1), which are electrically connected in the following manner:
2. The direct current grid short circuit protection matching test system according to claim 1, characterized in that, The generator (G) adopts a three-phase AC impulse generator; the output end of the generator (G) is connected with the primary winding of the test transformer through the phase separation and closing circuit breaker (HK1), the first operation circuit breaker (CD1), the adjusting resistor (Rt), the adjusting reactor (Lt) and the protection circuit breaker (BD1) in sequence; One end of the secondary side of the test transformer is connected to the first end of a test sample circuit breaker (QF1) through the rectification system and the shunt; the other end of the secondary side is connected to a sample (SP) through the rectification system, and the second end of the test sample circuit breaker (QF1) is also connected to the sample (SP). The specific circuit structure of the battery pack short-circuit current generating device further comprises a second operation circuit breaker (CD2); the first operation circuit breaker (CD1) and the adjusting resistor (Rt) are connected to the ground through the second operation circuit breaker (CD2) and a fixed resistor.
3. The direct current grid short circuit protection matching test system according to claim 2, characterized in that, The specific circuit structure of the battery pack short-circuit current generating device further comprises a grounding resistor (Rjd); the generator (G) is grounded through the grounding resistor (Rjd).
4. The direct current grid short circuit protection matching test system according to claim 2, characterized in that, The specific circuit structure of the generator set short-circuit current generating device comprises a DC power supply, a current limiting resistor, a wave modulation reactor (L2), a capacitor group (C2), a wave modulation resistor, a waveform sampling system and a control system, which are electrically connected in the following order:
5. The direct current grid short circuit protection matching test system of claim 1, wherein, The positive pole of the DC power supply is connected to the positive end of the capacitor group (C2) through the current limiting resistor, and the negative pole is directly connected to the negative end of the capacitor group, thereby forming a controllable charging circuit. The positive and negative terminals of the capacitor group (C2) are connected in parallel with a resonant modulation branch composed of the wave modulation reactor (L2) and the wave modulation resistor in series, for generating an oscillation-attenuated short-circuit current waveform in the discharge phase; the waveform sampling system is connected across the resonant modulation branch, and real-time current / voltage signals are collected and sent to the control system.
6. The direct current grid short circuit protection matching test system of claim 1, wherein, The measurement sensor used by the test system comprises a voltage sensor, a current sensor, a shunt, and a pure resistance voltage divider, and the output signals of the measurement sensor are transmitted to the data acquisition instrument by optical fiber after being converted by an optical isolator.
7. The direct current grid short circuit protection matching test system of claim 2, wherein, The connection circuit of the battery pack short-circuit current generating device and the generator set short-circuit current generating device is provided with a test sample circuit breaker (QF1), a first vacuum circuit breaker (QF3), a bus tie switch, a shunt I system, a shunt IC, and a shunt I total, and is electrically connected in the following manner: The positive and negative output terminals of the battery pack short-circuit current generating device are connected to the positive and negative common buses through the test sample circuit breaker (QF1); the positive and negative output terminals of the generator set short-circuit current generating device are connected to the same positive and negative common buses through the first vacuum circuit breaker (QF3), thereby realizing parallel connection with the battery circuit; the bus tie switch is connected across the positive and negative common buses and used as a short-circuit switch to form a short-circuit test point; The shunt I system is connected in series in the positive electrode circuit of the battery pack short-circuit current generating device and used for independently collecting the current waveform thereof; the shunt IC is connected in series in the positive electrode circuit of the generator set short-circuit current generating device and used for independently collecting the current waveform thereof; The shunt I total is connected in series in the positive common bus and used for collecting the total short-circuit current waveform after superposition of the two devices; By closing the test sample circuit breaker (QF1) and the first vacuum circuit breaker (QF3) at different times or simultaneously and then closing the bus tie switch, the superimposed waveform of the two current waveforms can be obtained at the short-circuit test point, so as to verify whether the expected waveform meets the requirements.
8. A DC grid short circuit protection matching test method using the DC grid short circuit protection matching test system according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: Step 1, parameter pre-calculation: for the battery pack short-circuit current generating device, the DC side inductance Lt and the resistance Rt to be input are calculated according to Ohm's law and the time constant formula; for the generator set short-circuit current generating device, the resistance, the capacitance C2, and the inductance L2 to be input are calculated according to the target open circuit voltage, the short-circuit current peak value, and the time required for the current to rise to the peak value; Step 2, battery circuit pre-adjustment: when the test sample circuit breaker (QF1) is in an open state, the generator output voltage is gradually increased until the DC port voltage reaches the target open circuit voltage, otherwise the voltage is continuously fine-adjusted until the target is met; Step 3, battery circuit waveform fine-adjustment: the test sample circuit breaker (QF1) is closed to short-circuit the DC port, and the short-circuit duration is controlled by timing; the shunt I system current waveform is collected, and if the current value or the time constant deviates from the target, the process returns to step 1 to fine-adjust Lt and Rt until the waveform meets the target requirements. Step 4, generator set circuit pre-adjustment: disconnect the open circuit switch and connect the charging circuit switch, gradually increase the DC power from zero voltage to the target open circuit voltage, and then disconnect the charging switch after the capacitor voltage is stable. Immediately close the short circuit switch to complete the discharge. Collect the current waveform of the shunt IC. If the peak value arrival time deviates from the target, return to step 1, fine-tune C2 or L2, until the waveform meets the target requirements. Step 5, superimposed waveform verification: connect the battery pack short-circuit current generator through the test product circuit breaker (QF1) and the generator set short-circuit current generator through the first vacuum circuit breaker (QF3). Then, connect the two positive and negative poles in parallel, and close the bus tie switch to form a short-circuit test point. At the same time or at different times, close the test product circuit breaker (QF1) and the first vacuum circuit breaker (QF3). Collect the total current waveform using the shunt IC. If the superimposed peak value or time parameter deviates from the expected value, repeat steps 3 and / or 4, fine-tune Lt, Rt, C2, L2, until the synthesized waveform meets the test requirements.
9. The DC grid short circuit protection matching test method according to claim 8, characterized in that, Step 3 and Step 4 fine-tuning is achieved by returning to Step 1 to recalculate and adjust Lt, Rt, C2, L2 until the waveform meets the target requirements.
10. The DC grid short circuit protection matching test method according to claim 8, characterized in that, Step 5 is achieved by closing the test product circuit breaker (QF1) and the first vacuum circuit breaker (QF3) at different times or simultaneously, and then using the bus tie switch to form a short-circuit test point to collect the synthesized waveform after superimposing the two current waveforms.