Distributed photovoltaic voltage peak value high protection test method and related device

Abstract

The invention discloses a distributed photovoltaic voltage peak value high protection test method and related device, and the method comprises the steps: building a primary loop model according to a topological structure and primary loop parameters, and connecting a test object to form a test simulation system; calibrating a three-phase harmonic voltage for testing according to a preset protection strategy of voltage peak protection to obtain a harmonic test voltage; when the system is stable, the protection action states under the action conditions that the voltage peak value accords with or does not accord with the preset protection strategy are verified through a voltage disturbance injection method according to the harmonic test voltage and the preset duration, and protection action verification results are obtained; and when the system recovers to be stable, verifying the protection outlet state under the condition that the voltage peak value meets or does not meet the return requirement of the preset protection strategy according to the harmonic test voltage, and obtaining a return action verification result. The technical problem that an existing test method cannot accurately verify the effectiveness of a distributed photovoltaic voltage peak value high protection mechanism can be solved.

Description

Technical Field

[0001] This application relates to the field of distributed power grids, and in particular to a method and apparatus for testing the peak voltage protection of distributed photovoltaic power. Background Technology

[0002] The grid-connection characteristics of distributed renewable energy sources have an increasingly prominent impact on the safety and stability of large power grids, becoming a crucial variable to be considered in large power grid simulation calculations. Domestic and international dispatching agency practices have shown that distributed renewable energy sources are relatively weak in grid-connection performance and exhibit specific protective behaviors. To systematically understand the true characteristics of distributed renewable energy sources, accurately assess their impact boundaries on the safety and stability of large power grids, and support the construction of new power systems, it is necessary to conduct tests targeting the unique characteristics of distributed renewable energy sources and research their testing methods.

[0003] High peak voltage protection is a special protection measure for distributed photovoltaic (PV) systems compared to centralized renewable energy sources. It primarily addresses harmonic voltage issues in distributed PV systems connected to the distribution network. Its operating logic involves "detecting the maximum peak line voltage within a grid cycle, determining if protection is applied, and if the voltage exceeds a threshold, protection continues for 5 seconds; if the voltage is below the threshold, protection continues for 5 seconds, then the alarm is cleared and the inverter restarts." This logic differs from traditional harmonic protection strategies. Therefore, current protection testing methods cannot accurately verify the effectiveness of this protection mechanism, making it difficult to determine the operating range of distributed PV systems and thus failing to provide support for safe grid operation. Summary of the Invention

[0004] This application provides a method and related apparatus for testing the peak voltage protection of distributed photovoltaic systems, which solves the technical problem that existing testing methods cannot accurately verify the effectiveness of the peak voltage protection mechanism of distributed photovoltaic systems.

[0005] In view of this, the first aspect of this application provides a method for testing the peak voltage protection of distributed photovoltaic systems, comprising:

[0006] In the real-time simulation system, a primary circuit model is built based on the topology and primary circuit parameters of the distributed photovoltaic system. After the test object is connected, the model can be put into normal operation, thus forming a test simulation system.

[0007] The three-phase harmonic voltage used for testing is calibrated according to the preset protection strategy in the voltage peak protection process to obtain the harmonic test voltage. The preset protection strategy includes action logic, action threshold, action delay, return threshold and return delay.

[0008] Under stable system conditions, the protection action status is verified by voltage perturbation injection method based on the harmonic test voltage and preset duration, respectively, for voltage peak values ​​that meet and do not meet the operation conditions of the preset protection strategy, and the protection action verification results are obtained.

[0009] Once the system stabilizes, the protection output status is verified based on the harmonic test voltage to determine whether the voltage peak meets or does not meet the return requirements of the preset protection strategy, thus obtaining the return action verification result.

[0010] Preferably, the step of calibrating the three-phase harmonic voltage for testing according to the preset protection strategy during the voltage peak protection process to obtain the harmonic test voltage includes:

[0011] Configure preset protection strategies based on the voltage peak protection mechanism;

[0012] Based on the preset protection strategy, a harmonic injection loop that can be switched on and off and is connected in series with the system power supply is built on the power supply side of the test simulation system;

[0013] Three-phase harmonic voltages are generated by a disturbance voltage source connected to the harmonic injection circuit;

[0014] The three-phase harmonic voltages are calibrated according to the preset protection strategy to obtain harmonic test voltages, which include a first amplitude voltage, a second amplitude voltage, and a third amplitude voltage.

[0015] Preferably, under stable system conditions, the protection operation status is verified by voltage disturbance injection method based on the harmonic test voltage and preset duration, respectively, for voltage peak values ​​that meet and do not meet the operating conditions of the preset protection strategy, to obtain protection operation verification results, including:

[0016] When the system is stable, a first amplitude voltage is injected into the test terminal by voltage perturbation injection method to make the voltage peak value conform to the action logic of the preset protection strategy and not meet the action threshold, thereby verifying whether the protection action state is non-action.

[0017] The voltage perturbation injection method injects a second amplitude voltage at the test end and continues for a first preset duration, causing the voltage peak value to conform to the action logic and action threshold of the preset protection strategy, and not to conform to the action delay, thereby verifying whether the protection action state is non-action.

[0018] A second amplitude voltage is injected into the test terminal by means of the voltage disturbance injection method and maintained for a second preset duration, so that the voltage peak value meets all the action conditions of the preset protection strategy, and the protection action status is verified to be active.

[0019] The voltage perturbation injection method is used to calculate and inject a third amplitude voltage, causing the voltage peak value to conform to the return logic of the preset protection strategy and not meet the return threshold, thereby verifying whether the protection action has been reset and generating a protection action verification result.

[0020] Preferably, the step of verifying the protection output state under the condition that the voltage peak value meets or does not meet the return requirements of the preset protection strategy based on the harmonic test voltage after the system has recovered and stabilized, and obtaining the return action verification result, includes:

[0021] If the voltage peak meets the return threshold of the preset protection strategy but does not meet the return delay after the system returns to stability, a second amplitude voltage is injected at the test terminal to verify whether the protection output state is not reset.

[0022] If the voltage peak value meets all the return requirements of the preset protection strategy, then verify whether the protection output status is reset and generate a return action verification result.

[0023] A second aspect of this application provides a distributed photovoltaic voltage peak high protection test device, comprising:

[0024] The simulation building unit is used to build a primary circuit model in a real-time simulation system based on the topology and primary circuit parameters of a distributed photovoltaic system. After being connected to the test object, it can run normally and form a test simulation system.

[0025] The harmonic calibration unit is used to calibrate the three-phase harmonic voltage for testing according to the preset protection strategy in the voltage peak protection process, and obtain the harmonic test voltage. The preset protection strategy includes action logic, action threshold, action delay, return threshold and return delay.

[0026] The action verification unit is used to verify the protection action status under the action conditions of the voltage peak conforming to and not conforming to the preset protection strategy by the voltage perturbation injection method according to the harmonic test voltage and the preset duration under the stable system condition, and obtain the protection action verification result.

[0027] The reset verification unit is used to verify the protection output status based on the harmonic test voltage under whether the voltage peak meets or does not meet the return requirements of the preset protection strategy when the system returns to stability, and obtain the return action verification result.

[0028] Preferably, the harmonic calibration unit is specifically used for:

[0029] Configure preset protection strategies based on the voltage peak protection mechanism;

[0030] Based on the preset protection strategy, a harmonic injection loop that can be switched on and off and is connected in series with the system power supply is built on the power supply side of the test simulation system;

[0031] Three-phase harmonic voltages are generated by a disturbance voltage source connected through the harmonic injection circuit;

[0032] The three-phase harmonic voltages are calibrated according to the preset protection strategy to obtain harmonic test voltages, which include a first amplitude voltage, a second amplitude voltage, and a third amplitude voltage.

[0033] Preferably, the action verification unit is specifically used for:

[0034] When the system is stable, a first amplitude voltage is injected into the test terminal by voltage perturbation injection method to make the voltage peak value conform to the action logic of the preset protection strategy and not meet the action threshold, thereby verifying whether the protection action state is non-action.

[0035] The voltage perturbation injection method injects a second amplitude voltage at the test end and continues for a first preset duration, causing the voltage peak value to conform to the action logic and action threshold of the preset protection strategy, and not to conform to the action delay, thereby verifying whether the protection action state is non-action.

[0036] A second amplitude voltage is injected into the test terminal by means of the voltage disturbance injection method and maintained for a second preset duration, so that the voltage peak value meets all the action conditions of the preset protection strategy, and the protection action status is verified to be active.

[0037] The voltage perturbation injection method is used to calculate and inject a third amplitude voltage, causing the voltage peak value to conform to the return logic of the preset protection strategy and not meet the return threshold, thereby verifying whether the protection action has been reset and generating a protection action verification result.

[0038] Preferably, the reset verification unit is specifically used for:

[0039] If the voltage peak meets the return threshold of the preset protection strategy but does not meet the return delay after the system returns to stability, a second amplitude voltage is injected at the test terminal to verify whether the protection output state is not reset.

[0040] If the voltage peak value meets all the return requirements of the preset protection strategy, then verify whether the protection output status is reset and generate a return action verification result.

[0041] A third aspect of this application provides a distributed photovoltaic voltage peak high protection test device, the device including a processor and a memory;

[0042] The memory is used to store program code and transmit the program code to the processor;

[0043] The processor is used to execute the distributed photovoltaic voltage peak high protection test method described in the first aspect according to the instructions in the program code.

[0044] The fourth aspect of this application provides a computer-readable storage medium for storing program code for executing the distributed photovoltaic voltage peak high protection test method described in the first aspect.

[0045] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0046] This application provides a method for testing distributed photovoltaic (PV) voltage peak protection, comprising: building a primary circuit model in a real-time simulation system based on the topology and primary circuit parameters of the distributed PV system, connecting the test object, and achieving normal operation to form a test simulation system; calibrating the three-phase harmonic voltage used for testing according to a preset protection strategy during the voltage peak protection process to obtain the harmonic test voltage, wherein the preset protection strategy includes action logic, action threshold, action delay, return threshold, and return delay; under stable system conditions, verifying the protection action status under the action conditions of voltage peak conforming to and not conforming to the preset protection strategy by means of voltage disturbance injection method based on the harmonic test voltage and preset duration, respectively, to obtain the protection action verification result; and under stable system conditions, verifying the protection output status under the return requirements of voltage peak conforming to and not conforming to the preset protection strategy based on the harmonic test voltage, to obtain the return action verification result.

[0047] The distributed photovoltaic (PV) voltage peak high protection test method provided in this application offers a specialized test scheme for distributed PV voltage peak high protection, filling the gap in existing technologies that lack this protection test. By simulating the real operating environment, it can fully verify the accuracy and effectiveness of the protection mechanism and accurately determine the operating range of distributed PV. Based on this scheme, it achieves effective testing of voltage peak protection strategies, actions, thresholds, and delays, providing reliable test data for assessing the impact boundaries of distributed energy systems on the safety and stability of the large power grid, thus contributing to the establishment of new power systems. Therefore, this application solves the technical problem that existing test methods cannot accurately verify the effectiveness of distributed PV voltage peak high protection mechanisms. Attached Figure Description

[0048] Figure 1 A schematic flowchart illustrating a method for testing the peak voltage protection of distributed photovoltaic systems, provided in an embodiment of this application;

[0049] Figure 2 This is a schematic diagram of the structure of a distributed photovoltaic voltage peak high protection test device provided in an embodiment of this application. Detailed Implementation

[0050] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0051] For easier understanding, please refer to Figure 1 An embodiment of a distributed photovoltaic voltage peak high protection test method provided in this application includes:

[0052] Step 101: In the real-time simulation system, a primary circuit model is built based on the topology and primary circuit parameters of the distributed photovoltaic system. After connecting the test object, it is put into normal operation, forming a test simulation system.

[0053] Taking a distributed photovoltaic (PV) grid as an example, the construction of the test simulation system mainly includes two operations: primary loop modeling and test object connection and operation. The primary loop modeling process specifically includes building the PV array model, DC combiner and support circuits, inverter main circuit, distribution network access loop, and model parameter verification. The test object connection process specifically includes hardware interface construction and semi-physical integration testing. To ensure the test simulation system meets subsequent testing requirements, this embodiment can also optimize model adaptability, such as adding a protection signal monitoring module and reserving a disturbance injection interface.

[0054] The process of building a photovoltaic array model requires inputting parameters such as open-circuit voltage, short-circuit current, and maximum power point voltage / current of each component into the component attributes, which must be consistent with the actual component parameters. You can also add an "MPPT controller model" to simulate the maximum power point tracking function of the actual photovoltaic system, ensuring that the output power characteristics of the model are consistent with the real system.

[0055] The DC bus and support circuit setup involves connecting a DC circuit breaker and a DC surge protector in series, and a DC support capacitor in parallel. The DC circuit breaker is a 10kW unit with a system rated current of approximately 20A; the DC support capacitor has a capacity of 2000 kcal / m³. It has a withstand voltage of 1000V; it can also add equivalent resistance elements to the model according to the actual junction box line resistance to simulate DC side line loss and achieve parameter calibration.

[0056] The main circuit construction of the inverter includes topology selection, filter circuit construction, and control interface reservation. Topology selection involves using IGBT modules to build a single-phase full-bridge inverter topology. The filter circuit can be constructed using series filter inductors and parallel filter capacitors. Then, by adjusting the filter parameters to match those of the actual inverter, the harmonic characteristics of the AC output waveform can be ensured to match the real device. The control interface reservation can be achieved by building an analog acquisition module to reserve a hardware interface with the semi-physical controller.

[0057] The construction of the distribution network access circuit includes the construction of distribution transformer models, low-voltage line models, and distribution network power supply models. The distribution transformer model can use the "Two-WindingTransformer" component, and input parameters such as capacity of 50kVA, transformation ratio of 10kV / 0.4kV, and short-circuit impedance of 4% to simulate an actual distribution transformer. The low-voltage line model can use the "RLCLine" component, and input parameters such as resistance of 0.05Ω and reactance of 0.04mH for a length of 0.5km to simulate a low-voltage distribution network line. The distribution network power supply model can use the "ACVoltageSource" component, set to an ideal sinusoidal voltage of 220V / 50Hz to simulate a stable power supply on the distribution network side.

[0058] Model parameter verification includes unperturbed steady-state testing and dynamic response verification. The former involves running the model and recording the output power at the photovoltaic array's maximum power point, as well as the inverter's AC output voltage, current, and THD. These data are then compared with actual steady-state data, and the deviation is controlled within a specified range. Within; the latter can simulate a decrease in photovoltaic illuminance from 1000W / m² to 800W / m², and record the response time of the inverter output power. Generally, it should be ≤0.5s to make it consistent with the dynamic characteristics of the actual inverter and ensure the dynamic accuracy of the model.

[0059] The hardware interface setup includes signal acquisition interface settings, drive signal interface settings, and communication interface settings. The signal acquisition interface settings can convert the DC voltage, DC current, AC voltage, and AC current signals in the simulation model into 4-20mA standard signals through a data acquisition card, and connect them to the ADC acquisition port of the semi-physical controller. The drive signal interface settings can convert the PWM drive signal output by the semi-physical controller into a 15V level signal required for IGBT driving through an isolation drive module, and connect it to the IGBT drive port in the simulation model. The communication interface settings can connect the controller and the simulation software via Ethernet to achieve bidirectional transmission of control commands and status data.

[0060] The semi-physical simulation test includes communication link testing, closed-loop control verification, and protection signal interface verification. Communication link testing involves initiating communication between the controller and the simulation software, verifying that the status data upload cycle should not exceed 10ms and the control command response time should not exceed 50ms, ensuring stable communication without packet loss. Closed-loop control verification involves running the semi-physical simulation system. The controller collects electrical signals from the simulation model, outputs PWM commands to control the IGBT switches in the simulation model, and records the waveforms of the inverter's AC output voltage and current. These parameters should be consistent with the output waveforms when the controller drives the physical inverter alone, verifying the effectiveness of the closed-loop control. Protection signal interface verification involves simulating a DC overvoltage fault. The controller should output an overvoltage protection action signal, and the simulation model, upon receiving the signal, cuts off the inverter output, verifying the transmission and response logic of the protection signal.

[0061] This embodiment fully replicates the primary topology, parameter characteristics, and control logic of a 10kW distributed photovoltaic system by constructing a test simulation system. When harmonic disturbances are subsequently injected, the voltage peak signal detected by the controller and the protection action response logic are consistent with the performance under real power grid conditions, ensuring the authenticity of the test results. Furthermore, the simulation model can precisely control interference factors such as photovoltaic irradiance and distribution network voltage, allowing multiple subsequent tests to be conducted under the same initial conditions, avoiding the non-reproducibility of test results caused by environmental factors in the real system. Additionally, subsequent tests require the injection of harmonics exceeding the rated voltage, such as achieving a voltage peak of 360V, exceeding the action threshold. In a real system, this could lead to equipment damage or distribution network fluctuations, but the simulation model can avoid this risk through parameter limitations without affecting the simulation of the test conditions.

[0062] Step 102: Calibrate the three-phase harmonic voltage for testing according to the preset protection strategy in the voltage peak protection process to obtain the harmonic test voltage. The preset protection strategy includes action logic, action threshold, action delay, return threshold and return delay.

[0063] The voltage peak protection mechanism in this embodiment is a preset protection strategy, which includes, but is not limited to, action logic, action threshold, action delay, return threshold, and return delay. The three-phase harmonic voltage is generated by simulating the superposition of the fundamental wave and harmonics to produce the maximum line voltage peak value, thereby providing data support for high voltage peak protection testing.

[0064] The harmonic test voltage required in this embodiment can be calibrated according to the preset protection strategy, ensuring the accuracy and effectiveness of the harmonic test voltage. In other words, it ensures that the judgment criteria of the test side and the protection side are consistent, avoiding situations where the test side considers the peak value to be within the acceptable range, but the protection side fails to detect it. The harmonic test voltage can be accurately categorized based on the calibration operation into operating voltages that meet the protection strategy conditions, non-operating voltages that do not meet the protection strategy conditions, and return voltages that can be accurately reset after the system stabilizes. This operation provides accurate and reliable test voltage support for subsequent testing operations, ensuring the reliability of the entire testing process.

[0065] Further, step 102 includes:

[0066] Configure preset protection strategies based on the voltage peak protection mechanism;

[0067] Based on the preset protection strategy, a harmonic injection loop that can be switched on and off and is connected in series with the system power supply is built on the power supply side of the test simulation system;

[0068] Three-phase harmonic voltages are generated by a disturbance voltage source connected to a harmonic injection circuit;

[0069] The three-phase harmonic voltages are calibrated according to the preset protection strategy to obtain the harmonic test voltage, which includes the first amplitude voltage, the second amplitude voltage, and the third amplitude voltage.

[0070] This embodiment allows for the configuration of targeted preset protection strategies for high voltage peak protection, including specific parameters such as the action logic, action threshold, action delay, return threshold, and return delay for voltage peaks. In addition to providing voltage peak protection, the preset protection strategy can also provide calibration data for harmonic voltages during the testing phase.

[0071] This embodiment establishes a reversible harmonic injection loop on the power supply side of the test simulation system, which can accurately inject three-phase harmonic voltages of a specified amplitude, and the injected signal can be accurately detected by the photovoltaic controller. The specific process of building this disturbance loop includes confirming the loop connection location, building the core loop of the three-phase disturbance voltage source, adding basic auxiliary components, and verifying the loop reversible function and injection effectiveness.

[0072] The circuit connection location confirmation operation involves selecting the series node between the "AC output terminal of the distributed photovoltaic inverter" and the "distribution network access point" in the simulation model as the disturbance injection point. This means that the AC voltage output by the inverter passes through this node before being connected to the distribution network line and grid power supply. This location ensures that the injected harmonic voltage, after being superimposed with the grid fundamental voltage, is directly captured by the voltage acquisition port of the photovoltaic controller, meeting the requirement of "injection close to the photovoltaic side."

[0073] The process of building the core circuit of the three-phase disturbance voltage source includes calling core components, connecting series circuits, and simplifying control logic. The component calling process is as follows: Search for "Three-PhaseVoltageSource" in the PSCAD component library, which is the three-phase voltage source, used as a harmonic disturbance source. Set the rated frequency to 50Hz, consistent with the grid fundamental frequency, and initially set the voltage amplitude to 0V, which can be adjusted later through parameters. Call "Three-PhaseCircuitBreaker," which is the three-phase circuit breaker, as the circuit's "can be enabled / disabled" control switch, and set the closing / opening control signals. The series circuit connection process is as follows: Connect the positive terminal of the three-phase disturbance voltage source to the side closest to the photovoltaic inverter, and the negative terminal to the side closest to the distribution network power supply, realizing "series connection between the disturbance voltage source and the system power supply." The A, B, and C phases of the three-phase disturbance voltage source correspond to the A, B, and C phases of the distribution network line, ensuring phase consistency and avoiding phase-to-phase short circuits. The simplified control logic setup process is as follows: add a "control signal module" to the three-phase circuit breaker, which is triggered by the internal logic of the software, without the need for additional hardware control, to achieve "one-click activation and deactivation" of the circuit.

[0074] Basic auxiliary components include current-limiting resistors, filter capacitors, and voltage monitoring components. A small 0.01Ω resistor is connected in series at the output of each of the three-phase disturbance voltage sources to prevent inrush currents from being generated when harmonics are injected, which could damage the inverter or distribution network components in the simulation model. A 1μF high-frequency filter capacitor is connected in parallel at the output of the disturbance voltage source to filter out noise signals in the injected harmonics and ensure that the injected voltage waveform is smooth. A "Three-Phase Voltage Meter" is used, which is a three-phase voltmeter connected in parallel on both sides of the disturbance injection point to monitor the total voltage peak value after superposition in real time, providing data support for "peak value confirmation" in subsequent tests.

[0075] The circuit breaker activation / deactivation function test includes a tripped state test and a closed state test. Set the three-phase circuit breaker to tripped, run the model, and monitor the voltage at the disturbance injection point. It should be consistent with the fundamental voltage of the power grid and have no additional harmonic superposition. Set the circuit breaker to closed, set the disturbance voltage source amplitude to 20V, which is also the peak value, run the model, and monitor the voltage waveform. The waveform after the fundamental voltage and the 20V harmonic superposition can be observed, proving that the circuit can be activated / deactivated normally.

[0076] The injected signal detection verification can activate the voltage acquisition function of the photovoltaic controller, record the voltage peak detected by the controller after closing, and compare it with the peak value monitored by the voltmeter in the simulation model. The deviation is controlled within ±1V, thus proving that the injected harmonic voltage can be accurately detected by the controller.

[0077] The harmonic voltage in this embodiment is used for testing the high voltage peak protection mechanism. Therefore, it needs to meet the testing requirements of this mechanism. The maximum value of the line voltage peak after the superposition of the fundamental wave and harmonics can be used to calibrate the harmonic injection amplitude, ensuring that the superimposed peak value corresponds accurately with the protection mechanism. Therefore, the harmonic test voltage obtained after calibration in this embodiment can be divided into a first amplitude voltage, a second amplitude voltage, and a third amplitude voltage according to the amplitude. Moreover, these voltages need to meet the following requirements: the first amplitude voltage is less than the protection action threshold, the second amplitude voltage is between the action threshold and the return threshold, and the third amplitude voltage is greater than the return threshold. This ensures that the harmonic amplitude is adjustable and can meet the requirements of the action threshold and the return threshold.

[0078] Specifically, the first step is to define the reference parameters and record the peak value of the grid base wave line voltage. Protective action threshold Return threshold Then calculate the target amplitude: according to "total peak value after superposition = fundamental peak value + harmonic peak value", calculate the first amplitude voltage separately. After superposition < Second amplitude voltage After superposition ≥ And < Third amplitude voltage After superposition ≥ The theoretical value is then used for simulation verification and calibration: the theoretical amplitude is injected into the simulation model, and the actual total peak value is read through monitoring components. If the deviation from the target value exceeds ±2%, the harmonic amplitude is fine-tuned until the target is met. Finally, the adjustable range is locked: the harmonic amplitude adjustment range is set to ensure coverage. It meets the requirements for testing under all operating conditions.

[0079] Step 103: Under stable system conditions, the protection action status is verified by voltage disturbance injection method based on harmonic test voltage and preset duration, respectively, under the action conditions of voltage peak value conforming to and not conforming to the preset protection strategy, and the protection action verification result is obtained.

[0080] The system begins the high voltage peak protection test in a stable state, with distributed photovoltaic power generation as the test condition and the grid voltage as an ideal sinusoidal voltage. Harmonic test voltages can be injected into the test terminal using a voltage disturbance injection method for a specified period. The system then samples the voltage peak value at its sampling frequency, calculates the period, and performs basic output processing. These parameters can be monitored in real time to analyze whether they meet the action logic and threshold conditions of the protection mechanism. If all conditions are met, the system monitors whether the protection operates correctly; if not, it monitors whether the protection does not operate correctly. The analysis results of these actions constitute the protection action verification results. The preset duration can be set according to actual test needs, such as 0s, 5s, 10s, etc., and is not limited here.

[0081] Further, step 103 includes:

[0082] When the system is stable, the first amplitude voltage is injected into the test terminal by voltage disturbance injection method to make the voltage peak value conform to the action logic of the preset protection strategy and not meet the action threshold, thus verifying whether the protection action state is not in action.

[0083] A second amplitude voltage is injected into the test terminal by voltage perturbation injection method and maintained for a first preset duration, so that the voltage peak value conforms to the action logic and action threshold of the preset protection strategy and does not conform to the action delay, thereby verifying whether the protection action state is non-action.

[0084] A second amplitude voltage is injected into the test terminal by voltage perturbation injection method and maintained for a second preset duration, so that the voltage peak value meets all the action conditions of the preset protection strategy, and the protection action status is verified to be active.

[0085] The voltage perturbation injection method is used to calculate and inject a third amplitude voltage, causing the voltage peak value to conform to the return logic of the preset protection strategy and not meet the return threshold, thereby verifying whether the protection action has been reset and generating a protection action verification result.

[0086] It should be noted that this embodiment uses a specific first amplitude voltage and a second amplitude voltage as examples to perform voltage injection operations and test the effectiveness of the protection strategy. The peak value of the grid fundamental line voltage during the test is... =311V, effective value is 220V; protection action threshold is =357.65V, the returned threshold is =326.55V; Harmonic test voltage amplitude setting: =30V, peak value after superposition is 341V < ; =50V, after superposition, the peak value is 361V≥ And < ; =20V, after superposition, the peak value is 331V≥ These correspond to the first amplitude voltage, the second amplitude voltage, and the third amplitude voltage, respectively; the action delay is 5 seconds, and the return delay is 5 seconds.

[0087] First test condition: Inject the first amplitude voltage, i.e. =30V, verify whether the system correctly fails to operate when it meets the protection action logic but not the action threshold. Start the test simulation system and wait for the photovoltaic output to stabilize, i.e., the power is about 10kW, and the grid voltage is an ideal sine wave with a peak value of 311V. Connect the disturbance circuit and inject a three-phase harmonic voltage with an amplitude of 30V, i.e., the first amplitude voltage. The total peak value after superposition is read by the monitoring element as about 341V, confirming that the action logic is met, but not reaching the threshold. If the protection device outputs no action signal after 10 seconds of continuous monitoring, and the inverter operates normally in grid connection, then it meets expectations and verifies the effectiveness of the protection mechanism at this time. It can be observed that the preset duration in the first test condition is 0 seconds, meaning there is no duration requirement.

[0088] In the second test condition, a second amplitude voltage is injected, namely... =50V, continuous for the first preset duration, i.e. =3s, verify whether the system correctly does not operate if it meets the action threshold but not the action delay. Disconnect the harmonics and wait for the system to return to the ideal sinusoidal voltage state. Then, connect the disturbance circuit, inject a second amplitude voltage of 50V, and start the timer. Confirm the system state; the peak voltage after the fundamental and harmonics are superimposed is approximately 361V. Continue timing for 3 seconds. Then, verify whether the protection does not operate during the 3-second harmonic disconnection period, and whether the inverter continues to run. If so, it meets expectations.

[0089] Third test condition: Injecting the second amplitude voltage, i.e. =50V, for the second preset duration, i.e. =6s, verify whether the protection operates correctly under the condition that the system meets the action threshold and action delay. The circuit breaker cuts off the harmonics. After the system returns to the ideal sinusoidal voltage state, the disturbance circuit is connected, and a second amplitude voltage of 50V is injected, and the timer is started; confirm the system state, that is, the peak voltage after the superposition of the fundamental wave and harmonics is about 361V, and continue timing for 6s; if the protection device triggers the action signal when the timer reaches 5s, the inverter stops, the harmonics are cut off at 6s, and the protection state is maintained; if so, it meets the expectations.

[0090] Fourth test condition: Injecting the third amplitude voltage, i.e. =20V, verifying whether the system meets the return logic, but does not meet the return threshold, and whether the protection will not reset. After the third test condition, the protection device is in the protection action state, and the inverter stops; here, a disturbance circuit is connected, injecting a third amplitude voltage of 20V to confirm the system status, that is, the voltage peak after the superposition of fundamental and harmonic waves is about 331V; continuous monitoring for 8s, if the protection does not reset and the inverter does not restart, it is in line with expectations.

[0091] Step 104: After the system returns to stability, verify the protection output status based on the harmonic test voltage, whether the voltage peak meets or does not meet the return requirements of the preset protection strategy, and obtain the return action verification result.

[0092] Once the system returns to a stable state, i.e., the distributed photovoltaic system is in test condition and the grid voltage is an ideal sinusoidal voltage, the effectiveness of the reset and return mechanism of the protection mechanism can be tested. This test process also requires a complete test based on harmonic test voltage injection. The reset state when the voltage peak meets or does not meet the return requirements is verified. Only when both tests meet expectations can the verification be considered successful, i.e., the protection mechanism is effective and accurate.

[0093] Further, step 104 includes:

[0094] If the voltage peak meets the return threshold of the preset protection strategy but does not meet the return delay after the system returns to stability, a second amplitude voltage is injected at the test end to verify whether the protection output status is not reset.

[0095] If the voltage peak meets all the return requirements of the preset protection strategy, then verify whether the protection output status is reset and generate the return action verification result.

[0096] Fifth test condition: If the system does not reach the return delay after recovering to steady state, inject a second amplitude voltage, i.e. =50V, verify that the system meets the return threshold, but does not meet the return delay requirement, and check whether the protection will not reset. The circuit breaker cuts off the harmonics, and after the system recovers to 311V, the return timing starts; after 3 seconds, a 50V three-phase harmonic voltage is injected again. Status confirmation is performed; the peak value after the fundamental and harmonics are superimposed is approximately 361V, and the return timing is interrupted. If the protection remains active and the inverter does not restart, it meets expectations.

[0097] Sixth test condition: If the system recovers to steady state and meets the return threshold and return delay, verify whether the protection resets correctly. The circuit breaker cuts off harmonics, and after the system recovers to 311V, the return timing is started. If, after 3 seconds of timing, no harmonics are injected and the voltage peak stabilizes at 311V, both the return threshold and return delay meet the requirements. If, after 5 seconds of timing, the protection resets, the alarm is cleared, and the inverter automatically restarts and reconnects to the grid, then it meets expectations.

[0098] This embodiment comprehensively covers the core scenarios of the action and reset conditions in the protection mechanism through the above six operating conditions, accurately verifying the logical correctness of the high voltage peak protection's principle of "acting when it should act, resetting when it should reset, and not malfunctioning in critical states," and thoroughly eliminating potential problems such as "threshold judgment deviation" and "delay timing failure." Furthermore, based on... The gradient amplitude design clarified the actual response boundaries of the protection action threshold of 357.65V and the return threshold of 326.55V, verified the matching degree between the parameter settings and the protection logic, and ensured that the parameters did not have the problems of "too loose leading to grid risks" or "too strict leading to frequent shutdowns".

[0099] Furthermore, the operating conditions designed in this embodiment simulate real-world scenarios that may be encountered in the actual operation of distributed photovoltaic systems, such as "slight voltage peak exceedance," "short-term exceedance," "continuous exceedance," and "recovery after exceedance." The test results can directly reflect the protection response characteristics under real grid conditions, providing reliable data support for practical applications. Moreover, this embodiment not only tests the operating logic of the protection device itself but also simultaneously verifies the inverter's "shutdown-hold-restart" linkage response, ensuring the coordination between protection actions and equipment control, and avoiding linkage faults such as "protection action but equipment not shut down" or "protection reset but equipment not restarted."

[0100] The various operating condition test operations in this embodiment are designed with a logical progression of "not meeting the threshold - meeting the threshold but insufficient delay - meeting the threshold + action delay - not meeting the return threshold - meeting the return threshold but insufficient delay - meeting the return threshold + reset delay", forming a complete test closed loop without omitting any core scenarios. Moreover, this solution is highly targeted, with harmonic amplitude ( Strictly match the protection threshold, time parameter ( By closely monitoring action / return delays, this test scheme ensures that each operating condition precisely focuses on a core verification point, avoiding ambiguity in test conclusions due to multivariate interference. Furthermore, this test scheme balances high repeatability and reliable results. Based on a simulation model and clearly defined baseline parameters, all operating conditions can be repeatedly tested under the same initial conditions, eliminating interference from environmental fluctuations in real systems, such as irradiance and distribution network voltage drift. Test results are consistent and traceable. Moreover, the test scheme in this embodiment is safe, controllable, and low-cost. By simulating over-threshold voltage disturbances in a simulated environment, it eliminates the need for risk testing in a real power grid, avoiding safety hazards such as equipment damage and grid fluctuations, while significantly reducing the manpower and material costs of on-site testing. In addition, this test method has wide adaptability and strong reusability. The test logic is not limited to a 10kW distributed photovoltaic model; by simply adjusting the baseline parameters, it can be adapted to distributed photovoltaic systems of different capacities and protection parameters, demonstrating high reusability.

[0101] The distributed photovoltaic (PV) voltage peak high protection test method provided in this application offers a specialized test scheme for distributed PV voltage peak high protection, filling the gap in existing technologies that lack this protection test. By simulating the real operating environment, it can fully verify the accuracy and effectiveness of the protection mechanism and accurately determine the operating range of distributed PV. Based on this scheme, it achieves effective testing of voltage peak protection strategies, actions, thresholds, and delays, providing reliable test data for assessing the impact boundaries of distributed energy systems on the safety and stability of the large power grid, thus contributing to the establishment of new power systems. Therefore, this application embodiment can solve the technical problem that existing test methods cannot accurately verify the effectiveness of distributed PV voltage peak high protection mechanisms.

[0102] For easier understanding, please refer to Figure 2 This application provides an embodiment of a distributed photovoltaic voltage peak high protection test device, comprising:

[0103] The simulation building unit 201 is used to build a primary circuit model in the real-time simulation system based on the topology and primary circuit parameters of the distributed photovoltaic system. After being connected to the test object, it can run normally and form a test simulation system.

[0104] The harmonic calibration unit 202 is used to calibrate the three-phase harmonic voltage for testing according to the preset protection strategy in the voltage peak protection process, and obtain the harmonic test voltage. The preset protection strategy includes action logic, action threshold, action delay, return threshold and return delay.

[0105] The action verification unit 203 is used to verify the protection action status under the action conditions of voltage peak conforming to and not conforming to the preset protection strategy by the voltage disturbance injection method according to the harmonic test voltage and preset duration under the stable system condition, and obtain the protection action verification result.

[0106] The reset verification unit 204 is used to verify the protection output status based on the harmonic test voltage when the voltage peak meets or does not meet the return requirements of the preset protection strategy, and obtain the return action verification result.

[0107] Furthermore, the harmonic calibration unit 202 is specifically used for:

[0108] Configure preset protection strategies based on the voltage peak protection mechanism;

[0109] Based on the preset protection strategy, a harmonic injection loop that can be switched on and off and is connected in series with the system power supply is built on the power supply side of the test simulation system;

[0110] Three-phase harmonic voltages are generated by a disturbance voltage source connected through a harmonic injection circuit;

[0111] The three-phase harmonic voltages are calibrated according to the preset protection strategy to obtain the harmonic test voltage, which includes the first amplitude voltage, the second amplitude voltage, and the third amplitude voltage.

[0112] Furthermore, the motion verification unit 203 is specifically used for:

[0113] When the system is stable, the first amplitude voltage is injected into the test terminal by voltage disturbance injection method to make the voltage peak value conform to the action logic of the preset protection strategy and not meet the action threshold, thus verifying whether the protection action state is not in action.

[0114] A second amplitude voltage is injected into the test terminal by voltage perturbation injection method and maintained for a first preset duration, so that the voltage peak value conforms to the action logic and action threshold of the preset protection strategy and does not conform to the action delay, thereby verifying whether the protection action state is non-action.

[0115] A second amplitude voltage is injected into the test terminal by voltage perturbation injection method and maintained for a second preset duration, so that the voltage peak value meets all the action conditions of the preset protection strategy, and the protection action status is verified to be active.

[0116] The voltage perturbation injection method is used to calculate and inject a third amplitude voltage, causing the voltage peak value to conform to the return logic of the preset protection strategy and not meet the return threshold, thereby verifying whether the protection action has been reset and generating a protection action verification result.

[0117] Furthermore, the reset verification unit 204 is specifically used for:

[0118] If the voltage peak meets the return threshold of the preset protection strategy but does not meet the return delay after the system returns to stability, a second amplitude voltage is injected at the test end to verify whether the protection output status is not reset.

[0119] If the voltage peak meets all the return requirements of the preset protection strategy, then verify whether the protection output status is reset and generate the return action verification result.

[0120] This application also provides a distributed photovoltaic voltage peak high protection test device, the device including a processor and a memory;

[0121] The memory is used to store program code and transfer the program code to the processor;

[0122] The processor is used to execute a distributed photovoltaic voltage peak high protection test method according to the instructions in the program code in the above method embodiment.

[0123] This application also provides a computer-readable storage medium for storing program code for executing the distributed photovoltaic voltage peak high protection test method in the above method embodiments.

[0124] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0125] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0126] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0127] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for executing all or part of the steps of the methods described in the various embodiments of this application through a computer device (which may be a personal computer, server, or network device, etc.). The aforementioned storage medium includes: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.

[0128] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for testing the peak voltage protection of distributed photovoltaic systems, characterized in that, include: In the real-time simulation system, a primary circuit model is built based on the topology and primary circuit parameters of the distributed photovoltaic system. After the test object is connected, the model can be put into normal operation, thus forming a test simulation system. The three-phase harmonic voltage used for testing is calibrated according to the preset protection strategy in the voltage peak protection process to obtain the harmonic test voltage. The preset protection strategy includes action logic, action threshold, action delay, return threshold and return delay. Under stable system conditions, the protection action status is verified by voltage perturbation injection method based on the harmonic test voltage and preset duration, respectively, for voltage peak values ​​that meet and do not meet the operation conditions of the preset protection strategy, and the protection action verification results are obtained. Once the system stabilizes, the protection output status is verified based on the harmonic test voltage to determine whether the voltage peak meets or does not meet the return requirements of the preset protection strategy, thus obtaining the return action verification result.

2. The distributed photovoltaic voltage peak high protection test method according to claim 1, characterized in that, The process of calibrating the three-phase harmonic voltage for testing according to the preset protection strategy in the voltage peak protection process to obtain the harmonic test voltage includes: Configure preset protection strategies based on the voltage peak protection mechanism; Based on the preset protection strategy, a harmonic injection loop that can be switched on and off and is connected in series with the system power supply is built on the power supply side of the test simulation system; Three-phase harmonic voltages are generated by a disturbance voltage source connected to the harmonic injection circuit; The three-phase harmonic voltages are calibrated according to the preset protection strategy to obtain harmonic test voltages, which include a first amplitude voltage, a second amplitude voltage, and a third amplitude voltage.

3. The distributed photovoltaic voltage peak high protection test method according to claim 2, characterized in that, Under stable system conditions, the protection operation status is verified using a voltage disturbance injection method based on the harmonic test voltage and a preset duration, respectively, for voltage peak values ​​that conform to and do not conform to the preset protection strategy, to obtain protection operation verification results, including: When the system is stable, a first amplitude voltage is injected into the test terminal by voltage perturbation injection method to make the voltage peak value conform to the action logic of the preset protection strategy and not meet the action threshold, thereby verifying whether the protection action state is non-action. The voltage perturbation injection method injects a second amplitude voltage at the test end and continues for a first preset duration, causing the voltage peak value to conform to the action logic and action threshold of the preset protection strategy, and not to conform to the action delay, thereby verifying whether the protection action state is non-action. A second amplitude voltage is injected into the test terminal by means of the voltage disturbance injection method and maintained for a second preset duration, so that the voltage peak value meets all the action conditions of the preset protection strategy, and the protection action status is verified to be active. The voltage perturbation injection method is used to calculate and inject a third amplitude voltage, causing the voltage peak value to conform to the return logic of the preset protection strategy and not meet the return threshold, thereby verifying whether the protection action has been reset and generating a protection action verification result.

4. The distributed photovoltaic voltage peak high protection test method according to claim 2, characterized in that, When the system returns to stability, the protection output status is verified based on the harmonic test voltage to determine whether the voltage peak meets or does not meet the return requirements of the preset protection strategy, resulting in a return action verification result, including: If the voltage peak meets the return threshold of the preset protection strategy but does not meet the return delay after the system returns to stability, a second amplitude voltage is injected at the test terminal to verify whether the protection output state is not reset. If the voltage peak value meets all the return requirements of the preset protection strategy, then verify whether the protection output status is reset and generate a return action verification result.

5. A distributed photovoltaic voltage peak high protection test device, characterized in that, include: The simulation building unit is used to build a primary circuit model in a real-time simulation system based on the topology and primary circuit parameters of a distributed photovoltaic system. After being connected to the test object, it can run normally and form a test simulation system. The harmonic calibration unit is used to calibrate the three-phase harmonic voltage for testing according to the preset protection strategy in the voltage peak protection process, and obtain the harmonic test voltage. The preset protection strategy includes action logic, action threshold, action delay, return threshold and return delay. The action verification unit is used to verify the protection action status under the action conditions of the voltage peak conforming to and not conforming to the preset protection strategy by the voltage perturbation injection method according to the harmonic test voltage and the preset duration under the stable system condition, and obtain the protection action verification result. The reset verification unit is used to verify the protection output status based on the harmonic test voltage under whether the voltage peak meets or does not meet the return requirements of the preset protection strategy when the system returns to stability, and obtain the return action verification result.

6. The distributed photovoltaic voltage peak high protection test device according to claim 5, characterized in that, The harmonic calibration unit is specifically used for: Configure preset protection strategies based on the voltage peak protection mechanism; Based on the preset protection strategy, a harmonic injection loop that can be switched on and off and is connected in series with the system power supply is built on the power supply side of the test simulation system; Three-phase harmonic voltages are generated by a disturbance voltage source connected through the harmonic injection circuit; The three-phase harmonic voltages are calibrated according to the preset protection strategy to obtain harmonic test voltages, which include a first amplitude voltage, a second amplitude voltage, and a third amplitude voltage.

7. The distributed photovoltaic voltage peak high protection test device according to claim 6, characterized in that, The action verification unit is specifically used for: When the system is stable, a first amplitude voltage is injected into the test terminal by voltage perturbation injection method to make the voltage peak value conform to the action logic of the preset protection strategy and not meet the action threshold, thereby verifying whether the protection action state is non-action. The voltage perturbation injection method injects a second amplitude voltage at the test end and continues for a first preset duration, causing the voltage peak value to conform to the action logic and action threshold of the preset protection strategy, and not to conform to the action delay, thereby verifying whether the protection action state is non-action. A second amplitude voltage is injected into the test terminal by means of the voltage disturbance injection method and maintained for a second preset duration, so that the voltage peak value meets all the action conditions of the preset protection strategy, and the protection action status is verified to be active. The voltage perturbation injection method is used to calculate and inject a third amplitude voltage, causing the voltage peak value to conform to the return logic of the preset protection strategy and not meet the return threshold, thereby verifying whether the protection action has been reset and generating a protection action verification result.

8. The distributed photovoltaic voltage peak high protection test device according to claim 6, characterized in that, The reset verification unit is specifically used for: If the voltage peak meets the return threshold of the preset protection strategy but does not meet the return delay after the system returns to stability, a second amplitude voltage is injected at the test terminal to verify whether the protection output state is not reset. If the voltage peak value meets all the return requirements of the preset protection strategy, then verify whether the protection output status is reset and generate a return action verification result.

9. A distributed photovoltaic voltage peak high protection test device, characterized in that, The device includes a processor and a memory; The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the distributed photovoltaic voltage peak high protection test method according to any one of the claims 1-4 according to the instructions in the program code.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store program code for executing the distributed photovoltaic voltage peak high protection test method according to any one of claims 1-4.

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