Research On Detection And Protection Technology For High Voltage Power Supply System

Recently,high voltage power supply tends to high frequency application for high power density,in which,complex current waveforms exist,including line frequency component,dc component,and high frequency component,and thus higher requirements are proposed for the current sensor.This paper proposed new current sensors based on fluxgate principle,which was applied to current measurements in high voltage power supply.Two kinds of current sensor were designed: One is a fluxgate current sensor with a magnetic gathering shell and windings arranged orthogonally,and the other is a fluxgate current sensor with a magnetic gathering core for DC and AC application.The structures and operation modes were analyzed in detail and simulation studies were performed.The prototypes were designed,followed by test research.1.A fluxgate current sensor with a magnetic gathering shell and windings arranged orthogonally was proposed in this paper: The sensor consists of a U-shaped magnetic gathering shell.In the designed sensor,the exciting winding and secondary winding are arranged orthogonally so that the magnetic fields produced by the two windings are mutually orthogonal and decoupled.Introducing a magnetic gathering shell into the sensor is to concentrate the detected magnetic field and to reduce the interference of external stray field.Based on theoretical analysis and simulation results,a prototype was designed.Test results show that the proposed sensor can measure currents up to 25 A,and has an accuracy of 6‰ and a remarkable sensitivity.2.Based on the work above,a fluxgate current sensor with a magnetic gathering core and winding arranged orthogonally is proposed,which can achieve accurate measurement for dc,low-frequency ac and high-frequency ac: The sensor consists of two toroidal magnetic cores,and one core works in fluxgate principle for the measurement of dc and low-frequency ac.The other core is used for:(1)achieving measurement for medium or high-frequency based on current transformer effect,(2)gathering the magnetic field generated by exciting current into the core to improve the measurement precision and reduce the exciting magnetic potential,(3)reducing the interference of external stray field.The exciting winding and feedback winding are also arranged orthogonally so that the magnetic fields produced by two windings are mutually orthogonal and decoupled.Based on the theoretical analysis and simulation results,a prototype was designed.Test results show that the proposed sensor can measure currents up to 25 A,is less affected by hysteresis effects and has an accuracy of 0.4%,a 40 kHz small signal bandwidth and a remarkable sensitivity and linearity.3.The current sensors developed in this paper were applied to the high voltage high frequency power supply for electrostatic precipitation.The detection and the related protection function were simulated and tested,and the test results have good agreements with the simulation results,which shows that the current sensor developed can detect the current of high voltage power supply effectively,and the control system can effectively protect the power supply based on the test results.