Non-contact measurement method for voltage phasor

Abstract

The synchronous phasor measurement technology offers data for dynamic security monitoring in power systems. The non-contact voltage sensing technology has the advantages of safety, convenience and low cost, which is helpful for massive distribution of measurement devices. The defect of the existing non-contact voltage measurement technology is that the voltage probe may cause voltage distortion, and it is difficult to figure out the primary voltagephasor. In order to solve the problem of voltage distortion, the distortion law of voltage is revealed by analyzing the non-contact probe's equivalent circuit and transmission characteristic, and a phasor measurement algorithm for each in-band signal is proposed. Signal pre-processing is used to filter the out-of-band signals and noise first; The matrix pencil method is used to calculate the in-band signal's frequencies, which is used to build signal model, then the in-band signal phasors are figured out by fitting in time-domain; Lastly, the secondary phasors are restored to obtain the primary in-band signal phasors and synthetical phasor. The simulation results show that the proposed method can figure out the primary voltage phasor by using the sample of the probe output voltage. Experiment data show that the amplitude measurement error is less than 4.5%, the phase error is less than 1°, the frequency error is less than 0.04 Hz, and the frequency change rate error is less than 4 Hz/s.

Keywords

• synchronous phasor measurement algorithm
• non-contact voltage measurement
• capacitive coupling voltage probe
• measurement band extraction
• matrix pencil method
• least square method