Broadband Voltage Measurement And Sensor Performance Test Based On Capacitance-type Transformer Bushing

In the operation of the power system,the overvoltage of the power grid is one of the important causes of equipment failure.In order to ensure the safe and stable operation of the power grid and to formulate corresponding protection measures,it is very important for the effective monitoring and data analysis of the overvoltage of the power grid.In the existing overvoltage measuring devices,most of the front-end sensors in the device have poor high frequency response,which is difficult to meet the voltage measurement of lightning overvoltage frequency,and its own characteristics further limit the measurement bandwidth.In view of this,this paper researches a wide frequency voltage measurement method based on capacitance transformer bushing,and its main contents and conclusions are as follows:(1)The article briefly describes the measurement principle and installation method of the resistance-capacitance parallel voltage divider,and gives its constituent elements and structural design in detail.For the 110 kv capacitor bushing,the change trend of its equivalent parameters is mainly analyzed,and the component parameters of the resistorcapacitor voltage divider are selected based on this.At the same time,the measurement circuit at the back of the sensor is designed,including the follower circuit,filter circuit,and power conversion circuit,and the feasibility of the measurement is verified through simulation and experiment.In addition,the acquisition system was also designed,and the acquisition equipment and back-end software platform were selected.(2)By setting up a test platform based on 110 kv capacitive bushing,the resistancecapacitance parallel voltage divider was tested.The test includes the comparison test of the voltage division method,the frequency sweep test,measurement test of the standard lightning impulse and the square wave response test.The results show that the resistancecapacitance voltage divider and the capacitive bushing can achieve impedance matching,have good measurement linearity,and can accurately measure the lightning impulse voltage.After the analysis of the square wave response,the frequency response of the sensor meets the requirements of lightning overvoltage measurement.At the same time,according to the experimental results,the measurement uncertainty of the scale factor of voltage divider has been evaluated.(3)In view of the distortion of the output signal caused by the sensor’s own characteristics,this paper designs a signal recovery algorithm based on the incremental Wiener deconvolution method.Based on the traditional incremental Wiener deconvolution method,an improved algorithm for estimating the value of γ is proposed.After simulation analysis and experimental verification,the improved deconvolution algorithm can accurately recover the overvoltage input signal.Compared with the traditional incremental Wiener deconvolution algorithm,the improved algorithm reduces the amount of calculation and increases the practicability.The overvoltage measurement method proposed in this paper applied to the tap of the capacitive bushing of transformer has been tested by simulation and experiment.This method can accurately measure the overvoltage of standard lightning impulse frequency and meet the requirements of actual field measurement.At the same time,the research on the voltage sensor and the capacitive bushing also provides a reference for the development of the subsequent overvoltage measurement sensor.