Research On The Quantity Traceability Hierarchy Of Impulse Voltage Standard Secondary Measurement System

In high-voltage power systems,due to many factors such as natural lightning and human operation,transient overvoltages may occur,and the insulation performance of electrical equipment in these cases may be compromised.The accurate and reliable impulse withstand voltage test parameters are the premise to prevent the insulation damage of highvoltage electrical equipment and ensure the stable operation of the power system,which is directly related to the safety and economy of power production.Different from the traditional DC,AC high voltage and other steady-state signals,the measurement of impulse voltage requires two parameters,peak voltage and time parameters,covering high voltage and high frequency,and the measurement of time parameters requires the accurate measurement of peak voltage as the premise.Therefore,impulse high voltage measurement has always been a difficult and hotspot in the field of high-voltage measurement research.At present,the uncertainty level of China’s impulse voltage secondary measurement system has not yet reached the international advanced level.On the one hand,it is limited by the fact that there is no mature high-precision secondary voltage divider;on the other hand,it is limited by the quantity traceability hierarchy of the impulse voltage secondary measurement.This paper systematically studies the method of quantity traceability of impulse voltage secondary measurement system,the results achieved are as follows:In this paper,starting from the research of the transfer function of the attenuator,a high-precision secondary voltage divider is independently developed based on the transfer characteristics of the high input impedance RC hybrid attenuator.Theoretically analyzes the transfer characteristics of the three attenuators when measuring impulse voltage,and solves the approximate solution of the transfer function of the high input impedance RC hybrid attenuator.The stability of the scale factor of the RC attenuator is not affected by the stray capacitance.At the same time,the dynamic response of the RC attenuator is adjustable according to the transfer function.A simulation model for impulse voltage measurement of a high input impedance resistance-capacitor hybrid attenuator was established,and the variation curve of the scale factor and time parameter measurement was obtained,which provides theoretical guidance for the subsequent square wave response research of the impulse voltage secondary measurement system.According to the research results of the attenuator and actual engineering application requirements,a high-precision RC impulse secondary voltage divider with an attenuation ratio of 200 was independently developed.Through the performance check test,the scale factor of the digital recorder can be traced to the source.The performance verification test of the digital acquisition unit PXIe-5164 based on Lab VIEW programming was conducted,and its scale factor was traced back to the standard DC voltage source,and the static scale factor and the impulse scale factor were obtained.At the same time,in order to evaluate the effect of ambient temperature on the A/D module,a temperature rise experiment was designed and the temperature coefficient curve of PXIe-5164 was obtained.A method for traceability of the secondary measurement system of impulse voltage was proposed,and finally a set of standard secondary measurement device for impulse voltage was established.According to the adjustable characteristics of the dynamic response of the high-precision secondary voltage divider,the stability of the system’s impulse scale factor was studied based on the square wave response.The results show that the rise time of both sampling channels of the system is 5 ns,and the stability of the impulse scale factor is IEC standard.Trace the attenuation ratio of the high-precision secondary voltage divider to the standard AC voltage source,trace the system scale factor to the steady-state voltage source in the form of components according to the PXIe-5164 scale factor traceability results,and the traceability method of the whole set of impulse voltage secondary measurement system was given.Finally,the impulse scale factor of the system was traced to the low-voltage impulse standard wave source of the China Electrical Power Research Institute,and an impulse voltage standard secondary measurement system was established.The calibration results show that the peak value uncertainty of the system is 0.2%(k=2),the uncertainty of the front time is 0.9%(k=2),and the uncertainty of the half-peak time is 0.5%(k=2).The system uncertainty level is far better than the requirements of IEC 61083-1 for standard measurement systems.