Measurement Of Lightning-Induced Overvoltage In Power Distribution Lines Using Ceramic-Capacitor Insulator

In the distribution network,the lightning induced overvoltage is the primary factor that causes the lightning strike to trip.As the last link of power transmission,the distribution network directly targets a wide range of users,and people pay more and more attention to power quality.Therefore,real-time monitoring of the lightning induced overvoltage in the distribution network,realizing data and resource sharing is very important.It is of great theoretical significance and engineering application value to obtain the initial propagation characteristics of the lightning induced overvoltage,to develop corresponding protective measures and to improve the customer's power quality.Based on this,a line-powered intelligent insulator device with wireless data transmission is proposed for monitoring lightning-induced overvoltage.It can enable contact measurement of the overvoltage signal of the distribution network.The main components are high-voltage ceramic capacitors.A system that can directly measure the overvoltage of the distribution network over a long time was developed by designing the voltage dividing structure and insulation structure of the insulator using these capacitors.Capacitor voltage division and power electronic conversion are used to power the device.Wireless communication technology is applied to transmit overvoltage data to a monitoring system.The installation and application were carried out on an actual 10-kV distribution line to realize the monitoring of the lightning induced overvoltage of the distribution network.It has three main parts:sensing insulator,self-power-supply insulator,and wireless data transmission module.Both the self-power-supply insulator and the sensing insulator mainly use BaTiO₃ dielectric materials as the voltage dividing and power taking unit.According to the principle of capacitance division,the structure and parameters of the sensing insulator are designed.The lightning impulse response,output-input response and high frequency response characteristics of the sensing insulator were tested.The self-power-supply module was designed by simulation and experiment.Then the related modules were merged to test the hardware and software performance of the whole monitoring system.Finally,the temperature characteristics of the sensing device are tested.The test operation of the monitoring device and the collected overvoltage signal indicate that the device can monitor the inductive lightning overvoltage on the distribution network in real time.The results obtained in this paper are:?1?By testing the performance of the sensing insulator,The results show good transient response characteristics,stability and linearity.?2?By designing the self-power-supply circuit,the following test results are obtained:in the simulation,the output power is positively correlated with the increase of ceramic capacitor value C₃.The secondary side of the isolation transformer which is connected in series with a tuning inductor can significantly increase the output power of the self-power-supply circuit.In the experiment,the output voltage is constant at 12V,and the single-phase of the 8nF/180nF self-power-supply insulator can output a maximum of 2.03W.?3?The hardware and software performance of the whole online monitoring system was tested.The results show that the output response of the sensor is good under three conditions:normal operation of the transmission line,transient phase-to-ground fault of single-phase,and permanent phase-to-ground fault of single-phase.?4?By testing the temperature characteristics of the sensing device,the results show that:the value of the ceramic capacitor decreases as the temperature increases,the voltage division ratio fluctuates little with temperature,and the maximum change is about 2%.The test operation of the lightning inductive overvoltage monitoring device was realized,and the acquired overvoltage waveform was analyzed,and the feasibility of monitoring the lightning induced overvoltage is demonstrated.The lightning inductive overvoltage monitoring device based on ceramic capacitor insulator proposed in this paper has been successfully tested on the network,which can monitor the lightning inductive overvoltage.It is of great significance for obtaining the initial propagation characteristics of the lightning induced overvoltage and establishing the lightning protection system for the distribution network.