A method for power quality test proficiency verification

Abstract

The application discloses a power quality test capability verification method, wherein a power quality test device is connected to a harmonic voltage measuring point and a harmonic current measuring point of a capability verification device through a current sensor, the capability verification device is composed of a harmonic source and a load device, preset harmonic voltage stability values, harmonic current stability values, harmonic output times and harmonic containing rates are set in the power quality test capability verification device, harmonic voltage stability models and harmonic current stability models are constructed, and the effective values of the harmonic voltage and the harmonic current, three-phase output voltage root mean square values and three-phase current root mean square values are compared with the harmonic voltage stability models and the harmonic current stability models, so that whether the test capability of the power quality test device is qualified or not is judged, and the test limitation of the prior art which is only for single harmonic or load conditions is solved.

Description

Technical Field

[0001] This invention belongs to the field of power quality testing technology, and specifically relates to a method for verifying power quality testing capabilities. Background Technology

[0002] As power systems, photovoltaic systems, and energy storage systems become increasingly complex, power quality issues are having a growing impact on their stable operation and equipment safety. The importance of harmonic testing and analysis, in particular, is becoming increasingly prominent.

[0003] In existing technologies, for example, Chinese patent CN202384767U discloses a simplified equivalent model of harmonic sources. This model simplifies the filter design process by selecting sub-current harmonic sources that exceed the standard, thus solving the problem of cumbersome calculations in traditional filter design to some extent. However, this patent mainly focuses on filter design and does not address the standardization and accuracy of testing procedures. It also cannot comprehensively evaluate the testing capabilities of power quality testing equipment in practical applications, especially its performance under complex conditions such as high-frequency harmonics and nonlinear loads.

[0004] Chinese patent CN109617053A proposes a test and analysis method for the propagation coefficient of higher harmonics in power transmission and distribution lines, emphasizing the importance of higher harmonics in the power grid and providing insights for improving the safety of power grid operation. However, this patent focuses on the propagation characteristics analysis of higher harmonics, and there are still gaps in the verification of power quality testing technology itself, especially in the performance evaluation of testing equipment.

[0005] Chinese patent CN112333456A discloses a calibration method for power quality testing equipment, but this method only calibrates the fundamental voltage and current, and does not cover higher harmonics and three-phase unbalanced conditions; Chinese patent CN208705678U proposes a harmonic testing device, but it does not form a standardized capability verification process and cannot meet the unified testing requirements of batch equipment, which further highlights the necessity of the present invention.

[0006] Currently, with the increasing complexity of power systems, the measurement accuracy of power quality testing equipment directly impacts grid security. However, existing technologies for verifying laboratory power quality testing capabilities suffer from three core problems: lack of standardized procedures, limited coverage of specific operating conditions, and inability to conduct batch assessments. There is a lack of a systematic method to comprehensively verify the testing capabilities of these devices under various harmonic frequencies, amplitudes, and complex load conditions. This leads to potential biases in test results, affecting the effectiveness of power quality management, resulting in a lack of comparability in laboratory test results, failing to provide reliable data support for grid operation and maintenance, and potentially posing risks to grid security.

[0007] Therefore, there is an urgent need for a systematic and standardized method to verify the accuracy and reliability of power quality testing equipment in harmonic analysis, especially one that can cover complex scenarios such as high-frequency harmonics and nonlinear loads, in order to make up for the shortcomings of existing technologies in the standardization and comprehensiveness of power quality testing. Summary of the Invention

[0008] The technical problem that the present invention aims to solve is that the existing technology lacks a systematic and standardized method for verifying the capability of power quality testing, which cannot fully verify the measurement accuracy of power quality testing equipment under complex operating conditions such as high-frequency harmonics and nonlinear loads, and is difficult to meet the unified capability verification requirements of batch laboratories.

[0009] To address the aforementioned technical problems, the present invention provides a method for verifying power quality testing capabilities, comprising the following steps:

[0010] In the laboratory participating in the proficiency testing project, the power quality testing equipment is connected to the harmonic voltage measurement point and harmonic current measurement point of the proficiency testing device through a current sensor. The harmonic voltage measurement point and harmonic current measurement point are located on the four-phase lines A, B, C, and N marked in the proficiency testing device. The proficiency testing device consists of a harmonic source and a load device, which are connected by a wire harness. In the power quality testing capability verification device, the stable values ​​of harmonic voltage and harmonic current, test interval time, test duration, harmonic output number and content rate are preset, and a harmonic voltage stability model and a harmonic current stability model are constructed. At the harmonic voltage measurement point and the harmonic current measurement point, the test instruments are used to measure the harmonic components of multiple voltages, currents, harmonic voltages and harmonic currents output by the proficiency testing device. After performing Fourier analysis on each harmonic component, the amplitude of the corresponding frequency component is directly extracted as the effective value of the harmonic voltage and harmonic current. The harmonic voltage and harmonic current are calculated in combination with voltage and current. The root mean square value of the three-phase output voltage and the root mean square value of the three-phase current at the harmonic measurement point are calculated. The average value of the preset number of data is calculated and compared with the harmonic voltage stability model and harmonic current stability model constructed by the proficiency testing device to determine whether the power quality testing equipment is qualified. If the deviation between the measured value of the participating laboratory and the robust average value of all participating laboratories is within the allowable range, the testing capability is deemed qualified; otherwise, it is deemed unqualified. Record test results and instrument calibration data for result analysis.

[0011] Preferably, the harmonic source includes a digital oscillator and a high-speed boost circuit.

[0012] Preferably, the load device is configured as one or more combinations of purely resistive, inductive, or capacitive loads to simulate different types of electrical equipment.

[0013] Preferably, the current sensor is selected as a clamp-on current sensor or a ring current sensor according to the output current range.

[0014] This invention provides a method for verifying power quality testing capabilities. By synchronously and precisely controlling harmonic voltage and harmonic current parameters, and combining them with actual test conditions, it comprehensively verifies the measurement accuracy of power quality testing equipment under different harmonic frequencies and amplitudes, and evaluates the measurement performance of the power quality testing equipment. This not only helps to improve the standardization level of power quality testing and ensure the accuracy of test results, but also effectively protects the safety and stability of power grid operation, overcoming the limitations of existing technologies that only target single harmonic or load conditions. Attached Figure Description

[0015] Figure 1 Schematic diagram of the setup for power quality testing capability verification; Figure 2 This is a schematic diagram illustrating the verification process for power quality testing capabilities. Detailed Implementation

[0016] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0017] This invention provides a power quality testing capability verification method. It uses a controllable capability verification device to simulate various power quality conditions that may occur in a real power grid, thereby verifying the actual testing capabilities of a laboratory participating in power quality testing. The method includes the following steps: Equipment Connection: In the laboratory participating in the proficiency testing project, connect the power quality testing equipment and a current sensor with a matched range to the designated harmonic measurement point of the proficiency testing device, such as... Figure 1 As shown, it consists of a harmonic source and a load device, connected by a wire harness. The power quality testing equipment is connected in series with the line through a current sensor. The voltage measurement is performed by obtaining the signal in parallel. The harmonic voltage measurement point and the harmonic current measurement point are both located on the four-phase lines A, B, C, and N marked in the proficiency testing device.

[0018] The proficiency testing device consists of a harmonic source and a load. The harmonic source mainly includes a digital oscillator, a high-speed boost circuit, a filter, a switch controller, a transformer and rectifier, and a display and control unit. The digital oscillator is used to accurately generate harmonic signals of a set frequency, and the high-speed boost circuit regulates the harmonic voltage output. The load device can be configured as a purely resistive, inductive, or capacitive load, or a combination thereof, to simulate different types of electrical equipment.

[0019] Based on the output current range of the proficiency testing device, a clamp-on current sensor or a ring current sensor is selected.

[0020] The capability verification device is applicable to standards such as GB / T 14549-1993 "Power Quality - Harmonics in Public Power Grids" and GB / T36548-2024 "Test Procedure for Electrochemical Energy Storage Power Stations Connected to the Power Grid".

[0021] like Figure 2 As shown, harmonic parameters are set: Harmonic voltage stability values ​​and harmonic current stability values ​​are preset in the power quality testing proficiency testing device, and harmonic voltage stability models and harmonic current stability models are constructed to verify whether the preset data are stable. The stability evaluation standard complies with the requirements of CNAS-GL003:2018 "Guidelines for Evaluation of Uniformity and Stability of Proficiency Testing Samples". The harmonic source in the proficiency testing device accurately outputs harmonic voltage and current values ​​of specified orders (e.g., 1st fundamental, 3rd, 5th, and 7th harmonics). For example, the output fundamental voltage is set to 220V, while simultaneously superimposing a certain proportion of 3rd, 5th, and 7th harmonic voltages. Similarly, the corresponding harmonic current values ​​can also be set, and the load device is configured according to the output power requirements of the harmonic source.

[0022] Harmonic measurement: Using testing instruments at the harmonic voltage measurement point and the harmonic current measurement point, the harmonic components of the voltage, current, harmonic voltage and harmonic current output by the proficiency testing device are measured.

[0023] Data Analysis and Comparison: The measured harmonic components are read, and Fourier analysis is performed on each harmonic component. The amplitude of the corresponding frequency component is directly extracted as the effective value of the harmonic voltage and harmonic current. The harmonic voltage and harmonic current are calculated in combination with voltage and current. The root mean square value of the three-phase output voltage and the root mean square value of the three-phase current at the harmonic measurement point are calculated. The average value of the preset number of data is calculated and compared with the harmonic voltage stability model and harmonic current stability model constructed by the proficiency testing device. Based on the requirements of CNAS-GL002:2018 "Guidelines for Statistical Processing and Proficiency Evaluation of Proficiency Testing Results", the ability of the laboratory testing personnel to conduct power quality testing using power quality testing equipment is judged to be qualified.

[0024] If the deviation of the measured value from the participating laboratory from the robust average value of all participating laboratories is within the allowable range, the test capability is deemed acceptable; otherwise, it is deemed unacceptable.

[0025] The advantages of the technical solution of this invention are as follows: 1) By unifying the testing environment, testing parameters, wiring methods, and data processing methods, a standardized process for verifying power quality testing capabilities is established to achieve comparability and evaluability of test results from different laboratories.

[0026] 2) Ensure the accuracy of test results: By comparing the results with the stable values ​​calibrated by the device, the performance of the test equipment can be objectively evaluated, ensuring the reliability of its measurement results.

[0027] 3) Improve the performance and reliability of testing equipment: help users and manufacturers discover potential performance problems, thereby improving and optimizing the design and manufacturing of power quality testing equipment.

[0028] 4) Provide strong support for power quality management and grid operation safety: Accurate power quality testing is the key to effectively managing power quality issues, ensuring stable grid operation and equipment safety.

[0029] 5) It can provide data and image support for tracing the reasons for unqualified laboratory testing capabilities, and help the laboratory optimize the testing operation process.

[0030] Example 1 1) Participate in the preparation of a power quality testing device and a current sensor in the laboratory.

[0031] 2) The environmental conditions at the test site were: temperature: 25℃±5℃, humidity: 5%RH~90%RH, atmospheric pressure: 950hPa~1060hPa.

[0032] 3) Begin the experiment, the steps are as follows: 3.1) The proficiency testing implementation agency starts the harmonic source and load, sets the corresponding parameters, and applies a supply voltage of 220.0V; 3.2) Once the proficiency testing organization has verified the data stability through computer-based control software, the participating laboratories can begin testing; 3.3) Participate in the laboratory to arrange the equipment according to... Figure 1 The power quality testing equipment and current sensor must be connected to the harmonic measurement points of the sample in this proficiency testing. The testing instruments must be used to measure the voltage U, current I, harmonic voltage Uh, and harmonic current Ih at the harmonic measurement points. The power quality testing equipment will then collect and measure the values ​​of each harmonic voltage and current in real time.

[0033] 3.4) The laboratory set the test interval, test duration, and harmonic order (1st, 3rd, 5th, 7th) in the power quality testing equipment, and collected data at 10-second intervals, for a total of 30 data collections within a 300-second test duration; 3.5) During the testing process, participating laboratories shall take photos of the overall wiring of the instrument, the location of the harmonic measurement points, and the parameter setting interface of the power quality testing equipment. Each photo shall include the test time and the laboratory logo. At the same time, photos of the harmonic test data in the power quality testing equipment (or screenshots of the test result data in the software) shall be taken. The photos or screenshots may be used by the proficiency verification implementation agency to understand the testing details of the participating laboratories and to summarize the impact of different measurement equipment and wiring methods on the test results. 3.6) The participating laboratory reads and measures each harmonic component from the power quality testing equipment. After performing Fourier analysis on each harmonic component, the amplitude of the corresponding frequency component is directly extracted as the effective value of the harmonic voltage and harmonic current. The root mean square value of the three-phase output voltage, the root mean square value of the three-phase current, and the corresponding harmonic current (I1, I3, I5, I7) and harmonic voltage (U1, U3, U5, U7) at the harmonic measurement point are calculated. The average value of 30 data points is calculated and compared with the harmonic voltage stability model and harmonic current stability model constructed by the proficiency testing device to determine whether the power quality testing equipment is qualified. If the deviation between the measured value of the participating laboratory and the robust average value of all participating laboratories is within the allowable range, the testing capability is deemed qualified; otherwise, it is deemed unqualified.

[0034] 3.7) Participating laboratories shall complete the test results in the "Results Report & Test Survey Form" provided by the proficiency testing organization, and send the raw test data to the designated email address of the proficiency testing organization. They shall also submit a hard copy of the "Results Report & Test Survey Form" and electronic copies of all instrument calibration reports. The raw test data can be used to analyze the reasons for unsatisfactory results in the participating laboratories, and the instrument calibration reports are used to analyze the basis for unsatisfactory or significantly deviated results in the participating laboratories.

[0035] In fact, the present invention mainly evaluates the ability of a device to perform power quality testing by participating in the test data of a laboratory recording capability verification device and judging whether the harmonic voltage and harmonic current measured in the laboratory deviate significantly from the robust data.

Claims

1. A method for verifying power quality testing capabilities, characterized in that, Includes the following steps: In the laboratory participating in the proficiency testing project, the power quality testing equipment is connected to the harmonic voltage measurement point and harmonic current measurement point of the proficiency testing device through a current sensor. The harmonic voltage measurement point and harmonic current measurement point are located on the four-phase lines A, B, C, and N marked in the proficiency testing device. The proficiency testing device consists of a harmonic source and a load device, which are connected by a wire harness. In the power quality testing capability verification device, the stable values ​​of harmonic voltage and harmonic current, test interval time, test duration, harmonic output number and content rate are preset, and a harmonic voltage stability model and a harmonic current stability model are constructed. At the harmonic voltage measurement point and the harmonic current measurement point, the test instruments are used to measure the harmonic components of multiple voltages, currents, harmonic voltages and harmonic currents output by the proficiency testing device. After performing Fourier analysis on each harmonic component, the amplitude of the corresponding frequency component is directly extracted as the effective value of the harmonic voltage and harmonic current. The harmonic voltage and harmonic current are calculated in combination with voltage and current. The root mean square value of the three-phase output voltage and the root mean square value of the three-phase current at the harmonic measurement point are calculated. The average value of the preset number of data is calculated and compared with the harmonic voltage stability model and harmonic current stability model constructed by the proficiency testing device to determine whether the power quality testing equipment is qualified. If the deviation between the measured value of the participating laboratory and the robust average value of all participating laboratories is within the allowable range, the testing capability is deemed qualified; otherwise, it is deemed unqualified. Record test results and instrument calibration data for result analysis.

2. The power quality testing capability verification method as described in claim 1, characterized in that, The harmonic source includes a digital oscillator and a high-speed boost circuit.

3. The power quality testing capability verification method as described in claim 1, characterized in that, The load device is configured as needed to be one or more combinations of purely resistive, inductive, or capacitive loads to simulate different types of electrical equipment.

4. The power quality testing capability verification method as described in claim 1, characterized in that, The current sensor is selected as either a clamp-on current sensor or a ring current sensor based on the output current range.

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