Differential Non-contact Voltage Measurement Based on Harmonic Injection
At present,there is no effective and convenient dynamic calibration method for coupling capacitors based on capacitive coupling sensors,which affects the measurement accuracy.Therefore,a differential non-contact voltage measurement method based on harmonic injection was proposed.Firstly,the fundamental frequency signal was introduced into the measurement system using a sensing probe and an I-V converter.Secondly,the interference caused by external stray capacitance changes was reduced through a shield,and the probe was improved and a differential circuit structure was introduced to eliminate the influence of the op-amp input capacitance.Then,the harmonics were injected into the measurement circuit.After that,the measurement circuit was injected with harmonics,and the fundamental and harmonic signals in the response signal were extracted by discrete Fourier transformation(DFT),and the coupling capacitance parameter was solved by the ratio of the harmonic source to the harmonic response signal,and its dynamic calibration was achieved.Finally,the fundamental voltage signal was then measured by substituting the calibrated capacitance parameters into the fundamental equation.The proposed measurement method was shown by simulation results to meet the requirements for varying coupling capacitance correction in a 10 kV application scenario with a maximum voltage measurement error of less than 0.4％.
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维普
