AC voltage withstand test system

Abstract

The invention relates to an alternating current withstand voltage test system. The alternating current withstand voltage test system comprises a two-phase power supply synthesis module, a digital phase-locked loop module, a boosting module and a measurement and control module, the system further comprises a safety protection module and a fault restarting module. The alternating current withstand voltage test system has the beneficial effects that (1) the scheme of combining the two-phase power supply synthesis module, the digital phase-locked loop module and the boosting module is adopted, so that the alternating current withstand voltage test system can flexibly generate a fracture withstand voltage test voltage and a test voltage which meet a ground test of an isolating switch (vacuum switch), and the defect that a traditional test system is single in function is overcome; (2) a superposition feedforward compensator and a closed-loop controller are adopted, and the reliability, efficiency and safety of the test are improved through cooperative control of predictive compensation and feedback correction; and (3) the fault restart module is linked with the digital phase-locked loop module, the monitoring and control module and the safety protection module, so that the downtime caused by faults is reduced, and the overall performance and the operation efficiency of the test system are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power equipment detection, in particular to an AC withstand voltage test system. Background Art

[0002] In power systems, the insulation performance of high-voltage switches and electrical equipment is a key factor in ensuring the safe and stable operation of the power grid. Traditional insulation withstand voltage test equipment cannot meet the requirements of AC withstand voltage tests for disconnectors (vacuum switches). This is because, during AC withstand voltage tests, one end of the test piece must be grounded, causing the switch's break voltage to be as high as the relative ground voltage. However, test regulations require that the break voltage of disconnectors (vacuum switches) be higher than the relative ground voltage. Consequently, the voltage generators in traditional test equipment cannot generate voltages sufficient for both tests, rendering the test voltage unsuitable for the test regulations.

[0003] Furthermore, conventional AC withstand voltage test equipment for high-voltage switches suffers from complex operation, low test accuracy, and insufficient safety. Therefore, it is necessary to develop a versatile and flexible AC withstand voltage test system that can meet the withstand voltage test requirements of disconnectors (vacuum switches), while also improving the efficiency and accuracy of AC withstand voltage tests and ensuring operational safety. Summary of the Invention

[0004] Based on the above situation, the present invention aims to provide a multifunctional, high-precision, safe and reliable AC withstand voltage test system, which can flexibly generate the test voltage for the fracture withstand voltage test and the relative ground test that meet the requirements of the isolating switch (vacuum switch), improve the defect of the traditional test system with single function, and improve the efficiency and accuracy of the AC withstand voltage test to ensure safe operation.

[0005] The technical solutions adopted by the present invention to solve the technical problems are as follows:

[0006] The present invention provides an AC withstand voltage test system, comprising:

[0007] A two-phase power supply synthesis module is used to synthesize a two-phase low-voltage AC voltage according to the setting of the test voltage; a digital phase-locked loop module is connected to the two-phase power supply synthesis module, and is used to phase-lock and frequency-adjust the two-phase low-voltage AC voltage output by the two-phase power supply synthesis module; a boost module is connected to the digital phase-locked loop module, and is used to boost the two-phase low-voltage AC voltage output by the digital phase-locked loop module to the test voltage; a measurement and control module is connected to the boost module, and is used to measure the electrical parameters of the withstand voltage equipment, set test parameters, monitor the electrical parameters during the test, and control the system in real time; the electrical parameters include equipment voltage, equipment current, and equipment frequency; the test parameters include test voltage, test frequency, and test time; the AC withstand voltage test system introduces a feedforward compensator, which is integrated in the two-phase power supply synthesis module or / and the digital phase-locked loop module, and is used to quickly track the frequency and phase changes of the test voltage, adjust the two-phase low-voltage AC voltage output by the two-phase power supply synthesis module or the digital phase-locked loop module in advance, and reduce the response time of the system.

[0008] Furthermore, the two-phase power supply synthesis module includes: a first power supply unit, used to generate a first-phase low-voltage AC voltage; a second power supply unit, used to generate a second-phase low-voltage AC voltage; when the feedforward compensator is integrated into the two-phase power supply synthesis module, the feedforward compensator is used to respectively detect the frequency, phase and amplitude changes of the first-phase low-voltage AC voltage and the second-phase low-voltage AC voltage, calculate the compensation signal of each phase and adjust its frequency, phase and amplitude respectively; a synthesis unit, used to vector synthesize the first-phase low-voltage AC voltage and the second-phase low-voltage AC voltage, output the synthesized two-phase low-voltage AC voltage, and dynamically adjust the phase difference of the two-phase low-voltage AC voltage according to the test voltage. Furthermore, the digital phase-locked loop module includes: a phase detection unit for detecting the phase difference between the synthesized two-phase low-voltage AC voltage and the test voltage; a filtering unit for filtering the phase difference output by the phase detection unit; a voltage-controlled oscillator for adjusting its output frequency according to the control signal output by the filtering unit so that the phase of the two-phase low-voltage AC voltage and the test voltage remain consistent; a frequency division unit for dividing the high-frequency signal output by the voltage-controlled oscillator to obtain the required test frequency; when the feedforward compensator is integrated into the digital phase-locked loop module, the feedforward compensator is connected in parallel with the closed-loop controller integrated in the filtering unit to superimpose the fast response capability of the feedforward compensator and the high-precision adjustment capability of the closed-loop controller, thereby improving the dynamic performance and steady-state accuracy of the system.

[0009] Preferably, when the feedforward compensator is integrated into the two-phase power supply synthesis module and the digital phase-locked loop module respectively, the feedforward compensator in the two-phase power supply synthesis module is used to quickly respond to changes in the test demand signal to reduce the synthesized two-phase low-voltage AC voltage error, and the feedforward compensator in the digital phase-locked loop module is used to optimize the performance of the phase-locked loop, reduce the locking time and oscillation phenomenon, and reduce the dynamic error and steady-state error of the system through the dual feedforward compensation mechanism.

[0010] Furthermore, the boost module includes: a boost transformer, used to boost the two-phase low-voltage AC voltage regulated by the digital phase-locked loop module to a test voltage; a voltage regulating unit, used to adjust the input voltage of the boost transformer, thereby controlling the amplitude of the test voltage, and the voltage regulating unit adopts digital control technology and can accurately adjust the amplitude of the test voltage; a protection circuit, used to detect abnormal conditions during the boost process and cut off the input power of the boost transformer under abnormal conditions.

[0011] Furthermore, the measurement and control module includes: a parameter setting unit for setting test parameters; a measuring unit for measuring the electrical parameters of the voltage-resistant equipment during the test in real time; a control unit for controlling the system in real time according to the test parameters and measurement results, including start, stop, boost and buck operations; and a display unit for displaying the test parameters and measurement results.

[0012] Furthermore, the AC withstand voltage test system also includes: a safety protection module, which is connected to the measurement and control module, and is used to cut off the power supply under abnormal circumstances to protect the safety of equipment and operators; the safety protection module specifically includes: an overvoltage protection unit, which is used to detect whether the test voltage exceeds the set safety threshold, and cut off the power supply when the threshold is exceeded; an overcurrent protection unit, which is used to detect whether the test current exceeds the set safety threshold, and cut off the power supply when the threshold is exceeded; a discharge protection unit, which is used to detect whether discharge occurs in the test equipment, and cut off the power supply when discharge is detected.

[0013] Furthermore, the measurement and control module also includes: a communication interface unit for performing data communication with external devices to realize remote monitoring and data recording functions.

[0014] Furthermore, the AC withstand voltage test system also includes: a fault restart module, which is used to ensure that the system can be reliably restarted to quickly resume the test through fault detection, safety isolation, dynamic adjustment and energy management after a sudden fault. The fault restart module includes: a fault detection response unit, which is used to monitor the operating status data of the withstand voltage equipment in real time, including voltage, current, frequency, and temperature, identify the fault type according to the preset threshold, and cooperate with the safety protection module to trigger the system to cut off the power supply; a residual energy discharge unit, which is used to quickly discharge the electric energy at the fault point to below the safety threshold to avoid secondary breakdown or arc reignition; a restart strategy generation unit, which is used to dynamically adjust the restart parameters according to the fault type and equipment status; the restart parameters include voltage amplitude and boost slope; a dynamic phase synchronization adjustment unit, which is used to adjust the waveform phase of the output signal according to the phase difference between the two-phase low-voltage AC voltage collected by the digital phase-locked loop module and the test voltage; a remote monitoring unit, which is used to upload fault data to an external device in real time to realize remote fault monitoring and data recording functions.

[0015] The beneficial effects of the present invention include:

[0016] First, the present invention adopts a solution combining "two-phase power supply synthesis module + digital phase-locked loop module + boost module" to enable the AC withstand voltage test system to flexibly generate a test voltage that can meet both the break withstand voltage test voltage of the isolating switch (vacuum switch) and the relative ground test, thereby improving the defect of the traditional AC withstand voltage test system that has a single function and cannot generate a voltage that can meet both tests at the same time, so that the test voltage can meet the requirements of the test procedures.

[0017] Secondly, the present invention adopts a superimposed feedforward compensator and a closed-loop controller to solve the shortcomings of traditional AC withstand voltage test systems in dynamic response, anti-interference ability and steady-state accuracy through the coordinated control of predictive compensation and feedback correction, thereby improving the reliability, efficiency and safety of the test.

[0018] Thirdly, the fault restart module adopted in the present invention significantly improves the reliability and stability of the AC withstand voltage test system through the linkage with the digital phase-locked loop module, the monitoring and control module and the safety protection module, through rapid fault detection, intelligent restart strategy, dynamic adjustment and optimization, which not only reduces the downtime caused by faults, but also improves the overall performance and operation efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The structure of the AC withstand voltage test system provided by the embodiment of the present invention is shown in FIG. Figure 1 .

[0020] Figure 2 It is a structural schematic diagram of a two-phase power supply synthesis module provided by an embodiment of the present invention.

[0021] Figure 3 It is a schematic diagram of the structure of a digital phase-locked loop module provided by an embodiment of the present invention.

[0022] Figure 4 The structure of the AC withstand voltage test system provided by the embodiment of the present invention is shown in FIG. Figure 2 . DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] Traditional AC withstand voltage test systems are mainly used to detect the insulation performance of high-voltage electrical equipment (such as transformers, GIS equipment, cables, etc.). The core principle is to apply an AC voltage higher than the rated voltage of the equipment for a certain period of time to observe whether breakdown or discharge occurs. Traditional AC withstand voltage test systems have many core defects, including equipment size, safety performance, scope of application, measurement accuracy, single function and other issues, resulting in slow dynamic response, weak anti-interference ability, low safety and energy efficiency. With the development of power electronics technology and digital control algorithms, the demand for intelligent, fast response and energy efficiency improvement of AC withstand voltage test systems is increasing. Therefore, it is necessary to gradually upgrade through intelligent transformation to meet the testing needs of modern high-voltage equipment. At the same time, it is necessary to improve the problems of single function, poor flexibility and low efficiency of traditional AC test equipment.

[0025] In AC withstand voltage tests, the combination of two-phase power supply synthetic voltage and digital phase-locked loop technology can effectively solve problems in traditional tests such as large equipment size, low phase control accuracy, slow dynamic response, and single function, and expand the flexibility of test scenarios.

[0026] Please refer to Figure 1 The present application provides an AC withstand voltage test system that can generate a test voltage that meets the requirements of a disconnector (vacuum switch) withstand voltage test and a relative ground test, and has functions such as high control accuracy and fast dynamic response, including the following modules:

[0027] (1) Two-phase power synthesis module, used to synthesize two-phase low-voltage AC voltage according to the setting of test voltage.

[0028] Specifically, the following is a specific embodiment of a two-phase power synthesis module. It comprises a first power supply unit, which uses a high-precision inverter to output a first-phase low-voltage AC voltage with a frequency of 50Hz and an adjustable effective value range of 0 to 220V. A second power supply unit, which also uses a high-precision inverter to output a second-phase low-voltage AC voltage with a frequency of 50Hz and an adjustable effective value range of 0 to 220V. A synthesis unit, which synthesizes the first-phase and second-phase low-voltage AC voltages using vector synthesis technology. The synthesis unit contains a phase adjustment circuit and an amplitude balancing circuit, which can dynamically adjust the phase difference and amplitude ratio of the two-phase power supply signals according to test requirements to optimize the waveform quality of the test voltage. For example, by adjusting the phase adjustment circuit, the phase difference between the two-phase power supply signals can be adjusted within a range of 0° to 180°, thereby synthesizing the required test voltage.

[0029] (2) A digital phase-locked loop module, connected to the above-mentioned two-phase power synthesis module, is used to perform phase locking and frequency adjustment on the two-phase low-voltage AC voltage output by the two-phase power synthesis module.

[0030] The following is a specific embodiment of a digital phase-locked loop (DPLL) module. It comprises the following components: a phase detection unit, which utilizes a high-speed analog-to-digital converter (ADC) and a digital signal processor (DSP) to detect in real time the phase difference between the synthesized two-phase power supply signal and the test voltage. The test voltage is generated by a high-precision crystal oscillator within the system at a frequency of 50 Hz. The phase detection unit can detect the phase difference with an accuracy of 1° and convert the detection result into a digital signal for output. A filtering unit, which utilizes a digital filtering algorithm to filter the error signal output by the phase detection unit, removes noise and high-frequency interference, and improves signal stability. The filter unit's filter cutoff frequency can be adjusted based on actual needs, for example, to 10 Hz to ensure system response speed and stability during dynamic adjustment. A voltage-controlled oscillator (VCO), which adjusts its output frequency based on the control signal output by the filter unit, utilizes a high-precision digital PLL chip that can respond to frequency adjustment commands within 10 ms and stabilize the output frequency at the target value. Its frequency adjustment range is 45 Hz to 55 Hz, meeting the frequency requirements of various test scenarios. Frequency division unit: Divides the high-frequency signal output by the voltage-controlled oscillator to obtain the required test frequency. The frequency division unit uses a programmable divider that can flexibly adjust the division ratio according to the test parameters to ensure the accuracy of the test frequency.

[0031] (3) A boost module, connected to the digital phase-locked loop module, for boosting the two-phase low-voltage AC voltage output by the digital phase-locked loop module to a test voltage.

[0032] The following is a specific embodiment of the boost module. Its components include: boost transformer: a dry-type transformer with high insulation performance, whose primary winding inputs a regulated two-phase AC power signal, and the secondary winding outputs a high voltage. The rated capacity of the transformer is 100kVA, and the rated output voltage is 100kV. The transformer adopts a multi-layer insulation structure inside, which can withstand high voltage shocks and ensure the safety of the test process; voltage regulating unit: digital control technology is used to control the amplitude of the test voltage by adjusting the input voltage of the primary winding of the boost transformer. The voltage regulating unit contains a high-precision digital voltage regulator and feedback circuit, which can adjust the test voltage with an accuracy of 0.1kV to meet the voltage accuracy requirements under different test needs.

[0033] (4) A measurement and control module connected to the boost module, used to measure the electrical parameters of the withstand voltage equipment, set test parameters, monitor the electrical parameters during the test, and perform real-time control of the system; the electrical parameters include equipment voltage, equipment current, and equipment frequency; the test parameters include test voltage, test frequency, and test time.

[0034] The following is a specific embodiment of the measurement and control module, which includes the following components: A parameter setting unit: This unit utilizes a touchscreen interface, allowing the operator to set parameters such as test voltage, frequency, and time. For example, the test voltage setting range is 10 kV to 100 kV, the frequency setting range is 45 Hz to 55 Hz, and the test time range is 1 minute to 60 minutes. These settings are transmitted to the control unit via an internal communication bus. A measurement unit: This unit utilizes high-precision voltage and current sensors to measure electrical parameters such as voltage, current, and frequency in real time during the test. The voltage and current sensors have a measurement accuracy of 0.5, and the frequency measurement accuracy is 0.01 Hz. The measurement results are converted to digital signals via an analog-to-digital converter (ADC) and transmitted to the control unit for processing and display. A control unit: This unit utilizes a high-performance microprocessor (such as the ARM Cortex-M series) to provide real-time control of the system based on the set parameters and measurement results. The control unit can perform operations such as start, stop, voltage increase, and voltage decrease, and dynamically adjust test conditions based on the electrical parameters during the test. For example, when the measured test voltage approaches the set value, the control unit automatically slows the voltage ramp to ensure a smooth rise. The display unit uses a high-resolution LCD screen to display test parameters and measurement results in real time. The screen clearly displays information such as test voltage, current, frequency, and test time, making it easy for operators to monitor the test process. The screen also features a fault alarm function, providing timely information when the system detects an anomaly.

[0035] The following is the working principle of the AC withstand voltage test system for this application, including the main steps:

[0036] 1. Power Synthesis and Regulation: First, the first and second power supply units of the two-phase power synthesis module generate first-phase and second-phase low-voltage AC voltages, respectively. The synthesis unit's phase adjustment circuit and amplitude balancing circuit combine the two-phase voltages for vector synthesis, optimizing the waveform quality of the test voltage. The synthesized two-phase low-voltage AC voltage is input to the digital phase-locked loop module.

[0037] 2. Phase Locking and Frequency Adjustment: The phase detection unit of the digital phase-locked loop module detects the phase difference between the synthesized two-phase low-voltage AC voltage and the test voltage and transmits the error signal to the filtering unit. The filtering unit filters the error signal and then transmits it to the voltage-controlled oscillator (VCO). The VCO adjusts its output frequency based on the control signal to align the phase of the two-phase power supply signal with the reference signal. The frequency divider divides the high-frequency signal output by the VCO to obtain the required test frequency.

[0038] 3. Voltage Boosting and Testing: The regulated two-phase low-voltage AC voltage is input to the primary winding of the step-up transformer in the step-up module. The voltage regulator adjusts the input voltage of the step-up transformer, thereby controlling the amplitude of the test voltage. The step-up transformer boosts the input signal to the high voltage required for testing and applies it to the withstand voltage equipment.

[0039] 4. Measurement and Control: The measurement unit of the measurement and control module measures electrical parameters such as voltage, current, and frequency in real time during the test and transmits the measurement results to the control unit. The control unit controls the system in real time based on the set parameters and measurement results, including starting, stopping, and increasing and decreasing voltage. The control unit also transmits the measurement results and test parameters to the display unit for real-time display.

[0040] In order to enable the AC withstand voltage test system to better adapt to rapidly changing input signals and improve the stability and response speed of the system, the AC withstand voltage test system of this application introduces a feedforward compensator, which is integrated into the two-phase power supply synthesis module and / or the digital phase-locked loop module to quickly track the frequency and phase changes of the test requirement signal, adjust the two-phase low-voltage AC voltage output by the two-phase power supply synthesis module or the digital phase-locked loop module in advance, and reduce the response time of the system.

[0041] Specifically, introducing a feedforward compensator into an AC voltage withstand test system can significantly improve system stability and response speed. AC voltage withstand test systems require rapid response to input signal changes and maintain highly accurate output voltages. The feedforward compensator predicts input signal changes in advance and compensates the system, thereby reducing both dynamic and steady-state errors. During AC voltage withstand tests, the frequency or amplitude of the input signal may fluctuate. The feedforward compensator can quickly detect these changes and proactively adjust the system's output, reducing response time. By directly compensating for input signal variations, the feedforward compensator reduces the error signal that the closed-loop controller must process, thereby improving the system's steady-state accuracy. Under high-frequency or complex signal conditions, the feedforward compensation mechanism can reduce system oscillations and instability, thereby improving system reliability. The feedforward compensator can be integrated into either the two-phase power combiner module or the digital phase-locked loop (DPLL) module. The choice depends on the system's performance requirements and design goals. Integration into the two-phase power combiner module: This integration approach quickly reduces the error in the combined signal, alleviating the burden on the DPL module and improving overall system stability. Integrated into the digital phase-locked loop module: This integration method can more directly optimize the performance of the phase-locked loop, reduce the locking time and oscillation phenomenon, and thus improve the stability of the system.

[0042] In an AC withstand voltage test system, whether it is necessary to integrate feedforward compensators in the two-phase power synthesis module and the digital phase-locked loop module respectively depends on the specific requirements and design goals of the system.

[0043] In some complex application scenarios, it may be necessary to integrate feedforward compensators separately in the two-phase power combiner module and the digital phase-locked loop (DPLL) module to achieve better system performance. The advantages of this design include: dual compensation: The feedforward compensator in the two-phase power combiner module can quickly respond to input signal changes and reduce the error of the combined signal; while the feedforward compensator in the DPL module can further optimize the PLL performance, reducing lock time and oscillation. Improved system stability: The dual feedforward compensation mechanism can reduce the system's dynamic and steady-state errors, improving overall system stability. Enhanced interference immunity: Dual feedforward compensation improves system immunity to external interference and noise, improving system reliability. However, this design also increases system complexity and cost. Therefore, in actual applications, whether to integrate the feedforward compensators separately depends on the specific system requirements and design goals. If the system has high dynamic performance and stability requirements and the cost is acceptable, integrating the feedforward compensators separately in the two-phase power combiner module and the DPL module is a reasonable option.

[0044] Please refer to Figure 2In order to improve the performance and reliability of the system, enhance the safety and portability of the test, and expand the flexible application of the AC withstand voltage test system, the present application applies a two-phase power supply synthesis module in the AC withstand voltage test system. The two-phase power supply synthesis module includes: a first power supply unit for generating a first-phase low-voltage AC voltage; a second power supply unit for generating a second-phase low-voltage AC voltage; when the feedforward compensator is integrated into the two-phase power supply synthesis module, the feedforward compensator is used to respectively detect the frequency, phase and amplitude changes of the first-phase low-voltage AC voltage and the second-phase low-voltage AC voltage, calculate the compensation signal of each phase and adjust its frequency, phase and amplitude respectively; the synthesis unit is used to vector synthesize the first-phase low-voltage AC voltage and the second-phase low-voltage AC voltage, output the synthesized two-phase low-voltage AC voltage, and dynamically adjust the phase difference of the two-phase low-voltage AC voltage according to the test voltage.

[0045] Specifically, the application of a two-phase power synthesis module offers significant advantages, especially when integrated with a feedforward compensator, which significantly improves system response speed and stability. The synthesis unit is implemented by linearly superimposing the two-phase power signals using an operational amplifier and a resistor network. The synthesis unit contains phase adjustment and amplitude balancing circuits, dynamically adjusting the phase difference and amplitude ratio of the two-phase power signals based on test requirements. The feedforward compensator, integrated into the two-phase power synthesis module, rapidly adjusts the frequency and phase of the output signal to ensure that the test voltage and operating voltage are aligned in frequency and phase. Since the core of two-phase power synthesis voltage lies in orthogonal decomposition and vector superposition, its advantage lies in the mathematical and physical method of enabling a single synthesized voltage vector to simultaneously contain two independent voltage components (such as Vα and Vβ). By adjusting the amplitude and phase of Vα and Vβ, two different voltages are generated to meet both the fracture withstand voltage test and the phase-to-ground withstand voltage test. This allows the same two-phase power system to efficiently complete both insulation testing requirements, addressing the inability of traditional AC withstand voltage test systems to simultaneously generate two different voltages. This offers both economical and technological advantages.

[0046] Please refer to Figure 3, in order to improve the frequency and phase control accuracy of the system and enhance the stability and anti-interference ability of the system. And the fast response capability and flexible configuration options enable the AC withstand voltage test system to better adapt to a variety of test scenarios and needs. The use of digital phase-locked loop technology in the AC withstand voltage test system has become an indispensable part. The digital phase-locked loop module includes: a phase detection unit, which is used to detect the phase difference between the synthesized two-phase low-voltage AC voltage and the test voltage; a filtering unit, which is used to filter the phase difference signal output by the phase detection unit; a voltage-controlled oscillator, which is used to adjust its output frequency according to the control signal output by the filtering unit so that the phase of the two-phase low-voltage AC voltage and the test voltage is consistent; a frequency division unit, which is used to divide the high-frequency signal output by the voltage-controlled oscillator to obtain the required test frequency; when the feedforward compensator is integrated into the digital phase-locked loop module, the feedforward compensator is connected in parallel with the closed-loop controller integrated in the filtering unit to superimpose the fast response capability of the feedforward compensator and the high-precision adjustment capability of the closed-loop controller, thereby improving the dynamic performance and steady-state accuracy of the system.

[0047] Specifically, when a feedforward compensator is integrated into a digital phase-locked loop (DPLL) module, it is connected in parallel with the closed-loop controller integrated into the filter unit. This combines the fast response of the feedforward compensator with the high-precision regulation capability of the closed-loop controller, improving the system's dynamic performance and steady-state accuracy. The feedforward compensator detects changes in the input signal, quickly calculates a compensation signal, and adds it to the output signal of the closed-loop controller. This parallel structure combines the fast response of feedforward compensation with the high-precision regulation of closed-loop control, significantly improving the system's dynamic performance.

[0048] To boost the low-voltage signals input by the two-phase power synthesis module and the digital phase-locked loop module to the high voltage required for testing, the AC withstand voltage test system also includes a boost module. This module comprises a boost transformer, which boosts the two-phase low-voltage AC voltage regulated by the digital phase-locked loop module to the test voltage; a voltage regulator, which uses digital control technology to precisely adjust the amplitude of the test voltage by adjusting the input voltage of the boost transformer; and a protection circuit, which detects abnormalities during the boost process and shuts off the input power to the boost transformer in the event of an abnormality.

[0049] The following is a specific embodiment of a boost module. A boost transformer uses the principle of electromagnetic induction to boost the input voltage to the required output voltage. It primarily consists of an iron core, a primary winding, a secondary winding, insulation material, and a casing. The iron core is made of laminated silicon steel sheets, offering high magnetic permeability and low hysteresis losses. The primary winding is typically located outside the iron core and wound with thicker wire. The secondary winding is located inside the primary winding and wound with thinner wire. In an AC withstand voltage test system, the design of the boost transformer must consider high voltage, high current, and high insulation performance. For example, for a test scenario requiring a 220V input voltage boost to 1000V, the boost transformer's turns ratio should be designed based on the laws of electromagnetic induction. The voltage regulator utilizes digital control technology, enabling precise adjustment of the test voltage amplitude. A digital-to-analog converter (DAC) controlled by a digital signal processor (DSP) or microcontroller (MCU) converts digital signals into analog voltage signals, thereby adjusting the input voltage of the boost transformer. For example, using an ARM processor and the Qt 4.0 development environment, precise digital voltage regulation control can be achieved. Users can select the desired output voltage through the interface, and the system automatically adjusts the input voltage of the step-up transformer to achieve the desired test voltage. The protection circuit monitors the input voltage in real time via a voltage detection module. When the voltage exceeds a set threshold, it triggers a control circuit to cut off the power supply. The control circuit can be implemented using a single-chip microcomputer or logic gate circuits. For example, when the input voltage falls below 180V or exceeds 250V, the single-chip microcomputer will cut off the power supply via a relay and trigger an audible and visual alarm module to alert the user. The protection circuit monitors the input voltage in real time via a voltage detection module. When the voltage exceeds a set threshold, the single-chip microcomputer will cut off the power supply via a relay and trigger an audible and visual alarm module to alert the user. This design effectively prevents equipment damage caused by overvoltage or undervoltage, improving system safety and reliability. Through the above design and implementation, the use of a step-up module in an AC withstand voltage test system not only improves system performance and reliability, but also enhances the safety and portability of the test.

[0050] In order to enable the AC withstand voltage test system to have parameter setting and real-time measurement functions, ensure the accuracy and safety of the test process through automatic control and safety protection functions, and provide support for the evaluation of test results and subsequent research through data recording and analysis functions, and significantly improve the performance and reliability of the AC withstand voltage test system, the AC withstand voltage measurement system also includes a measurement and control module, specifically including: a parameter setting unit for setting test parameters; a measurement unit for real-time measurement of the electrical parameters of the withstand voltage equipment during the test; a control unit for real-time control of the system according to the test parameters and measurement results, including start, stop, boost, and buck operations; and a display unit for displaying the test parameters and measurement results.

[0051] The following is a specific embodiment of the measurement and control module. The parameter setting unit inputs test parameters through a touch screen or control panel, and the system automatically configures the test conditions based on the input parameters. For example, the user can set parameters such as the test voltage value, frequency range, and test time through the interface. The measurement unit uses high-precision voltage sensors and current sensors to collect voltage and current signals in real time during the test, and processes and analyzes them through a digital signal processor (DSP). The measurement results can be displayed in real time on the control panel or touch screen. The control unit uses a single-chip microcomputer or microcontroller (MCU) to automatically control the output voltage and frequency of the boost module based on the set test parameters and real-time measurement results. For example, when the measured test voltage reaches the set value, the control unit automatically stops the boost operation and starts timing. The display unit displays the test parameters and measurement results in real time through an LCD touch screen or LED display. The user can view parameters such as test voltage, current, and frequency through the touch screen and adjust them as needed. For example, the control system of an 80kV AC withstand voltage tester: Parameter setting unit: Set the test voltage, frequency, and time parameters through the touch screen. The user enters the test voltage (0-80kV), frequency range (50-60Hz), and test time (1-60 minutes). The measurement unit uses a digital voltmeter and ammeter to measure the voltage and current in real time during the test. The measurement results are displayed on the touchscreen, allowing the user to observe the test status in real time. The control unit uses a single-chip microcomputer to control the output voltage and frequency of the boost module according to the set test parameters. When the voltage reaches the set value, the microcontroller controls the boost module to stop boosting and starts timing. The display unit displays test parameters and measurement results on the LCD touchscreen. Users can view test parameters such as test voltage, current, and frequency on the touchscreen and adjust them as needed. UHV GIL On-site AC Withstand Voltage Test: The parameter setting unit sets the test voltage, frequency, and time parameters through the console. Users can enter the test voltage (e.g., 1150kV), frequency range (50-300Hz), and test time (1-60 minutes). The measurement unit uses high-precision voltage and current sensors to measure the voltage and current in real time during the test. The measurement results are displayed on the console, allowing the user to observe the test status in real time. Control Unit: This module controls the output voltage and frequency of the boost module through the microcontroller. When the voltage reaches the set value, the microcontroller controls the boost module to stop boosting and start timing. Display Unit: This module displays test parameters and measurement results on the console's display screen. Users can view test parameters such as voltage, current, and frequency on the display screen and adjust them as needed. Through the above design and implementation, the application of the measurement and control module in the AC withstand voltage test system not only improves the system's performance and reliability, but also enhances the safety and portability of the test.

[0052] Please refer to Figure 4The AC withstand voltage test system runs throughout the entire test cycle. To ensure the safety of personnel, equipment, and the test process, the AC withstand voltage test system also includes a safety protection module, which is connected to the above-mentioned measurement and control module. It is used to cut off the power supply under abnormal circumstances to protect the safety of equipment and operators. The safety protection module specifically includes: an overvoltage protection unit, which is used to detect whether the test voltage exceeds the set safety threshold and cut off the power supply when the threshold is exceeded; an overcurrent protection unit, which is used to detect whether the test current exceeds the set safety threshold and cut off the power supply when the threshold is exceeded; and a discharge protection unit, which is used to detect whether the test equipment has discharged and cut off the power supply when discharge is detected.

[0053] The following is a specific embodiment of the safety protection module. The overvoltage protection unit includes voltage detection: a high-precision voltage sensor is used to monitor the test voltage in real time. Threshold setting: a safety voltage threshold is preset in the system, such as 110% of the rated voltage. Power cut-off: when the test voltage exceeds the set threshold, a relay is used to cut off the input power to the step-up transformer. For example, in an 80kV AC withstand voltage test, when the test voltage exceeds the set 80kV threshold, the overvoltage protection unit immediately cuts off the power. The overcurrent protection unit includes current detection: a high-precision current sensor is used to monitor the test current in real time. Threshold setting: a safety current threshold is preset in the system, such as 120% of the rated current. Power cut-off: when the test current exceeds the set threshold, a relay is used to cut off the input power to the step-up transformer. For example, in an on-site AC withstand voltage test of a UHV GIL, when the test current exceeds the set threshold, the overcurrent protection unit immediately cuts off the power. The discharge protection unit includes discharge detection: a highly sensitive discharge detection sensor is used, such as a UHF sensor or an ultrasonic sensor. Power cutoff: When a discharge is detected, a relay disconnects the input power to the step-up transformer. For example, in a 10kV AC withstand voltage test, an insulating shield is used to detect discharge and disconnect the power supply if an anomaly is detected. Through the design and application of these safety protection modules, the AC withstand voltage test system effectively protects equipment and operators, ensuring the reliability and safety of the test process.

[0054] In order to realize remote monitoring and data recording functions, the AC withstand voltage test system is equipped with a communication interface unit for data communication with external equipment to realize remote monitoring and data recording functions.

[0055] The following is a specific embodiment of the communication interface unit. The communication interface unit implements: Remote monitoring. Through the communication interface unit, operators can remotely monitor various parameters during the test process, such as voltage, current, and frequency. Data logging. The communication interface unit can record and store data during the test in real time for subsequent analysis and tracing. Data communication: Data communication with external devices is achieved, supporting multiple communication protocols such as serial communication (RS232 / RS485), Ethernet communication, and wireless communication. Implementation methods include: Serial communication interface: RS232 / RS485: Use serial communication protocols (such as UART) to achieve communication with external devices. Ensure the accuracy of data transmission by setting parameters such as baud rate, data bits, and stop bits. For example, in a single-chip microcomputer controller, remote monitoring and data logging are achieved through communication with the host computer via the RS232 interface. Ethernet communication interface: TCP / IP protocol: Network communication with external devices is achieved through the Ethernet interface, supporting the TCP / IP protocol, facilitating remote monitoring and data transmission. For example, in a computer room remote monitoring system, remote monitoring and data logging of server equipment is achieved through the Ethernet interface. Wireless Communication Interfaces: Wi-Fi / Bluetooth / ZigBee: These wireless communication protocols enable communication with external devices, making them suitable for mobile and portable devices. Through the design and application of these communication interface units, the AC withstand voltage test system can achieve remote monitoring and data logging capabilities, improving the system's automation and reliability.

[0056] In order to detect faults and automatically attempt to recover during the AC withstand voltage test, thereby improving the efficiency and reliability of the test, the AC withstand voltage test system includes a fault restart module, which is used to ensure that the system can be reliably restarted and quickly resume the test through fault detection, safety isolation, dynamic adjustment and energy management after a sudden fault. The fault restart module includes: a fault detection and response unit, which is used to monitor the operating status data of the test equipment in real time, including voltage, current, frequency, and temperature, identify the fault type according to the preset threshold, and cooperate with the safety protection module to trigger the system to cut off the power supply; a residual energy discharge unit, which is used to quickly discharge the electrical energy at the fault point to below the safety threshold to avoid secondary breakdown or arc reignition; a restart strategy generation unit, which is used to dynamically adjust the restart parameters according to the fault type and equipment status; the restart parameters include voltage amplitude and boost slope; a dynamic phase synchronization adjustment unit, which is used to adjust the waveform phase of the output signal according to the phase difference of the test requirement signal collected by the digital phase-locked loop module; a remote monitoring unit, which is used to upload fault data to external equipment in real time to realize remote fault monitoring and data recording functions.

[0057] The following is a specific implementation of the fault restart module. The fault detection and response unit uses high-precision sensors to collect data such as voltage, current, frequency, and temperature. Thresholds are set, and when the monitored data exceeds the threshold, the fault detection and response unit is triggered. It works in conjunction with the safety protection module to cut off power to protect equipment and personnel. For example, in an AC withstand voltage test system, the measurement and control module collects operating and test voltage signals. When an anomaly is detected, the power is immediately cut off. The residual energy dissipation unit connects a current-limiting resistor in series with the test circuit to limit the magnitude of the fault current. A fast discharge circuit is used to quickly dissipate residual energy. For example, in withstand voltage testing of GIS equipment, a current-limiting resistor is installed to prevent secondary breakdown at the fault point. The restart strategy generation unit analyzes the fault type and equipment status to determine restart parameters. The restart parameters are dynamically adjusted to ensure a safe and reliable system restart. For example, in an 80kV AC withstand voltage tester, the restart parameters are dynamically adjusted based on the fault type and equipment status to ensure the safety and reliability of the test process. The dynamic phase synchronization adjustment unit uses digital phase-locked loop technology to monitor the phase of the test demand signal in real time. Dynamically adjust the waveform phase of the output signal to ensure synchronization with the test requirement signal. For example: In the AC withstand voltage test control system, the phase synchronization of the output signal and the test requirement signal is achieved through phase-locked loop technology. The remote monitoring unit uses a communication interface (such as RS232, Ethernet, etc.) to upload fault data to an external device. Realize remote monitoring and data recording functions to facilitate subsequent analysis and tracing. For example: In an 80kV AC withstand voltage test machine, remote monitoring and recording of fault data are achieved through communication with external devices through the RS232 serial port. Through the design and application examples of the above-mentioned fault restart module, the AC withstand voltage test system can effectively ensure the safety and reliability of the test process, improve test efficiency and equipment service life.

[0058] It should be noted that the application of two-phase power supply synthesis technology in AC withstand voltage test systems offers significant advantages, primarily in the following areas: 1. Flexible voltage parameter adjustment: Using vector synthesis technology, the two-phase power supply can dynamically adjust the output voltage amplitude, frequency, and phase to meet the test requirements of different devices under test. For example, the frequency range is extended: variable frequency output is supported from power frequency (50 / 60Hz) to medium frequency (300Hz). Precise voltage control: Specific test voltages can be generated by adjusting the amplitude ratio and phase difference of the two-phase voltages. Optimized waveform quality: The synthesized waveform is close to a sine wave (THD < 0.3%), reducing harmonic distortion interference on insulation evaluation and making it particularly suitable for high-precision partial discharge detection scenarios. 2. Simplified system structure and improved portability: Two-phase synthesis technology replaces the traditional series / parallel connection of multiple devices through vector superposition, significantly optimizing test system design. Reduced hardware redundancy: No additional test transformers or complex voltage regulators are required, reducing equipment size and weight (approximately one-third of traditional devices). Integrated control: Combining variable frequency power supply and digital phase-locked loop technology (DPLL) to achieve digital control of voltage frequency and phase, improving operational convenience. 3. High-precision steady-state control and fast dynamic response: Two-phase synthesis technology works in conjunction with the closed-loop controller through a built-in feedforward compensator to achieve efficient control: Dynamic response acceleration: The feedforward compensator pre-compensates for high-frequency disturbances (such as sudden load changes), shortening the step response time to milliseconds, avoiding the lag problem of traditional PID control. Steady-state error suppression: The closed-loop controller adopts an adaptive algorithm (such as sliding mode control), and the steady-state phase error can be controlled within 0.03°, and the amplitude error is less than ±0.5%, meeting the stringent requirements of the national standard for test voltage accuracy (±1%-3%). Enhanced anti-interference ability: Σ-Δ modulation technology suppresses quantization noise, and the output signal signal-to-noise ratio (SNR) reaches more than 70dB, which is suitable for high-sensitivity insulation detection. 4. Improved applicability and safety in multiple scenarios: Complex equipment testing: Supports collaborative testing of multiple devices (such as applying different frequency voltages to the high and low voltage sides of the transformer at the same time), simulating the insulation withstand capacity under multi-power grid-connected conditions. Safety protection mechanism: Real-time monitoring of current mutations (such as breakdown or discharge), and reducing the risk of insulation damage by quickly cutting off the synthetic voltage phase or amplitude. Environmental adaptability: Through the temperature / voltage compensation algorithm, the impact of PVT (process, voltage, temperature) drift on control accuracy is eliminated, and it is suitable for harsh field environments. 5. Economical and standardized adaptation reduces equipment costs: The application of wide bandgap semiconductor devices (such as SiC MOSFET) increases power density and reduces the high maintenance costs of traditional oil-type transformers. Compliance with international standards: The output waveform meets the equivalence requirements for power frequency withstand voltage of standards such as IEC 60664, and supports multi-national test specifications.In summary, two-phase power synthesis technology significantly improves the flexibility, accuracy, and safety of AC withstand voltage tests through dynamic vector control, modular design, and intelligent algorithm optimization. It is particularly suitable for variable-frequency withstand voltage testing of complex equipment such as high-voltage cables and transformers. Its technical advantages are highly consistent with the development trend of intelligent and lightweight power system equipment, and it is expected to be further promoted in the field of new energy equipment testing in the future. The following is an example of the AC withstand voltage test system of this application being applied to phase-to-ground testing.

[0059] In AC withstand voltage test systems, the phase-to-ground test is an important test method used to verify the insulation performance of equipment to ground. The following is a specific example of an AC withstand voltage test system based on two-phase power synthesis technology and digital phase-locked loop technology in the phase-to-ground test:

[0060] 1. System composition

[0061] Two-phase power synthesis module: Generates two-phase AC power signals and quickly adjusts the frequency and phase of the signals through a feedforward compensator.

[0062] Digital phase-locked loop module: ensures that the frequency and phase of the output signal are consistent with the test requirement signal.

[0063] Boost module: boosts the synthesized AC power signal to the high voltage required for the test.

[0064] Measurement and control module: monitors the electrical parameters during the test in real time and controls the test process according to the set parameters.

[0065] Safety protection module: cuts off power supply in abnormal situations to protect the safety of equipment and operators.

[0066] 2. Implementation steps

[0067] Step 1: The measurement and control module extracts the reference signal and the test voltage signal.

[0068] Step 2: The two-phase power synthesis module initially boosts the output voltage to 20-30V.

[0069] Step 4: Adjust the phase-locked loop and keep it in the same frequency and phase.

[0070] Step 6: The boost module adjusts the voltage until it reaches the specified value of the test and conducts the test.

[0071] Through the above embodiments, the application of the AC withstand voltage test system in the phase-to-ground test not only improves the efficiency and safety of the test, but also provides an effective solution for the insulation performance test of power equipment.

[0072] Those skilled in the art can make various other corresponding changes and deformations based on the technical solutions and concepts described above, and all of these changes and deformations should fall within the scope of protection of the claims of the present invention.

[0073] It should be noted that the embodiments described above are only some of the embodiments of the present invention, rather than all of the embodiments. The singular forms "a," "an," "the," and "it" used in the embodiments and the appended claims are intended to include the plural forms as well, unless the context clearly indicates otherwise.

Claims

1. An AC withstand voltage test system, characterized in that: include: Two-phase power synthesis module, used to synthesize two-phase low-voltage AC voltage according to the setting of test voltage; A digital phase-locked loop module is connected to the two-phase power synthesis module and is used to perform phase locking and frequency adjustment on the two-phase low-voltage AC voltage output by the two-phase power synthesis module; A boost module, connected to the digital phase-locked loop module, for boosting the two-phase low-voltage AC voltage output by the digital phase-locked loop module to a test voltage; A measurement and control module, connected to the boost module, is used to measure the electrical parameters of the withstand voltage equipment, set test parameters, monitor the electrical parameters during the test, and control the system in real time; the electrical parameters include equipment voltage, equipment current, and equipment frequency; the test parameters include test voltage, test frequency, and test time; The AC withstand voltage test system introduces a feedforward compensator, which is integrated into a two-phase power supply synthesis module and / or a digital phase-locked loop module to quickly track the frequency and phase changes of the test voltage, adjust the two-phase low-voltage AC voltage output by the two-phase power supply synthesis module or the digital phase-locked loop module in advance, and reduce the response time of the system.

2. The AC withstand voltage test system according to claim 1, characterized in that: The two-phase power synthesis module includes: a first power supply unit for generating a first-phase low-voltage AC voltage; a second power supply unit for generating a second-phase low-voltage AC voltage; When the feedforward compensator is integrated into the two-phase power synthesis module, the feedforward compensator is used to detect the frequency, phase and amplitude changes of the first-phase low-voltage AC voltage and the second-phase low-voltage AC voltage respectively, calculate the compensation signal of each phase and adjust its frequency, phase and amplitude respectively; The synthesis unit is used to vector synthesize the first-phase low-voltage AC voltage and the second-phase low-voltage AC voltage, output the synthesized two-phase low-voltage AC voltage, and dynamically adjust the phase difference between the two-phase low-voltage AC voltage according to the test voltage.

3. The AC withstand voltage test system according to claim 1, characterized in that: The digital phase-locked loop module includes: Phase detection unit, used to detect the phase difference between the synthesized two-phase low-voltage AC voltage and the test voltage; A filtering unit, configured to filter the phase difference signal output by the phase detection unit; The voltage-controlled oscillator is used to adjust its output frequency according to the control signal output by the filter unit so that the phase of the two-phase low-voltage AC voltage and the test voltage is consistent; The frequency dividing unit is used to divide the high frequency signal output by the voltage controlled oscillator to obtain the required test frequency; When the feedforward compensator is integrated into the digital phase-locked loop module, the feedforward compensator is connected in parallel with the closed-loop controller integrated in the filtering unit to superimpose the fast response capability of the feedforward compensator and the high-precision adjustment capability of the closed-loop controller, thereby improving the dynamic performance and steady-state accuracy of the system.

4. The AC withstand voltage test system according to claim 1, characterized in that: When the feedforward compensator is integrated into the two-phase power synthesis module and the digital phase-locked loop module respectively, the feedforward compensator in the two-phase power synthesis module is used to quickly respond to changes in the test voltage and reduce the synthesized two-phase low-voltage AC voltage error. The feedforward compensator in the digital phase-locked loop module is used to optimize the performance of the phase-locked loop, reduce the locking time and oscillation phenomenon, and reduce the dynamic error and steady-state error of the system through the dual feedforward compensation mechanism.

5. The AC withstand voltage test system according to claim 1, characterized in that: The boost module comprises: A step-up transformer is used to step up the two-phase low-voltage AC voltage regulated by the digital phase-locked loop module to a test voltage; A voltage regulating unit is used to adjust the input voltage of the step-up transformer, thereby controlling the amplitude of the test voltage. The voltage regulating unit adopts digital control technology and can accurately adjust the amplitude of the test voltage; A protection circuit is used to detect abnormal conditions during the boosting process and cut off the input power to the boost transformer in abnormal conditions.

6. The AC withstand voltage test system according to claim 1, characterized in that: The measurement and control module includes: Parameter setting unit, used to set test parameters; Measuring unit, used to measure the electrical parameters of the withstand voltage equipment in real time during the test; The control unit controls the system in real time according to the test parameters and measurement results, including start, stop, boost and buck operations; Display unit, used to display test parameters and measurement results.

7. The AC withstand voltage test system according to claim 1, characterized in that: The AC withstand voltage test system also includes: A safety protection module, connected to the measurement and control module, for cutting off power supply in abnormal situations to protect the safety of equipment and operators; The security protection module includes: Overvoltage protection unit, used to detect whether the test voltage exceeds the set safety threshold, and cut off the power supply when the threshold is exceeded; Overcurrent protection unit, used to detect whether the test current exceeds the set safety threshold, and cut off the power supply when the threshold is exceeded; The discharge protection unit is used to detect whether discharge occurs in the voltage-resistant equipment and cut off the power supply when discharge is detected.

8. The AC withstand voltage test system according to claim 1, characterized in that: The measurement and control module also includes: The communication interface unit is used to communicate data with external devices to realize remote monitoring and data recording functions.

9. The AC withstand voltage test system according to claim 7, characterized in that: The AC withstand voltage test system also includes: The fault restart module is used to ensure that the system can be restarted reliably and quickly resume testing after a sudden fault through fault detection, safety isolation, dynamic adjustment and energy management.

10. The AC withstand voltage test system according to claim 9, characterized in that: The fault restart module includes: The fault detection and response unit is used to monitor the operating status data of the voltage-resistant equipment in real time, including voltage, current, frequency, and temperature. It identifies the fault type based on the preset threshold and cooperates with the safety protection module to trigger the system to cut off the power supply. Residual energy discharge unit, used to quickly discharge the electrical energy at the fault point to below the safety threshold to avoid secondary breakdown or arc reignition; Generate a restart strategy unit for dynamically adjusting restart parameters according to the fault type and device status; the restart parameters include voltage amplitude and boost slope; A dynamic phase synchronization adjustment unit is used to adjust the waveform phase of the output signal according to the phase difference between the two-phase low-voltage AC voltage collected by the digital phase-locked loop module and the test voltage; The remote monitoring unit is used to upload fault data to external devices in real time, realizing remote fault monitoring and data recording functions.

Images