The Research And Design Of Voltage Measurement Device Based On The Theory Of Electric Field Coupling

Voltage measurement is an important link in the operation of power system and italso has significant influence in areas of power metering, relay protection andautomation equipment control. An accuracy and reliable voltage measurement ismeaningful in maintaining fair trade settlement of power, ensuring safe operation of thegrid and promoting the development of smart grid. Traditional voltage transformer hasshown more and more inadaptability in the develop trend of smart grid due to its size,weight, insulating cost, steady-state accuracy and transient response. In this paper, anew voltage probe is proposed based on the theory of electric field coupling and it isexpected to develop a non-contact method for power system voltage measuring thoughthe proposed voltage probe. The main work of this paper mainly embodies on thefollowing aspects:①A new idea to realize power system voltage measurement is proposed based onthe theory of electric field coupling. The feasibility of this method is proved throughtheoretical derivation. The basic measurement principle and frequency characteristics ofelectric field coupling probe is studied through the theoretical analysis. A working modeof the electric field coupling probe is selected to have the probe been suitable in powersystem application. The theoretical work provides a preparation for the design andoptimization of the probe.②Differential output circuit structure and multi-electrode parallel structure areproposed to solve a series of problems which are encountered in power frequencyvoltage measurement with the proposed probe being applied in power system. Theerrors caused by probe parameter perturbation are analyzed to put forward the goal andstrategy in probe designing and optimizing. The probe is modeled and simulated byAnsoft Maxwell, which is an electromagnetic field finite element calculation software.The optimization of sensor structure design parameters are obtained by finite elementsimulation. The probe is manufactured into printed circuit board to ensure thestandardization and consistency of probe parameters.③Measurement hardware circuit, which is used for signal conditioning anddigital acquisition of probe’s output signal, is designed and implemented. The PCsoftware program is developed by graphical programming software LabVIEW. The PCsoftware has an excellent man-machine interface and it implements the graphical display, analysis and saving for the waveform data sampled by measurement hardwarecircuit. Data and instruction communication is implemented between measurementhardware circuit and PC software program by using WIFI wireless network and UDPprotocol.④The test platform is set up for probe calibration and error test. The steady-stateaccuracy and transient response of the calibrated probe is tested with the test platformby comparing with a standard high voltage probe. The result shows that the probe canachieve the accuracy of a0.5class metering voltage transformer and have a quickresponse with rapidly changing primary voltage. The probe can meet the developmentof smart grid which needs voltage probe to be intelligent, minimized and convenient.