Modeling And Analysis Of Overvoltage Detection System For Power Cable

The advancement of modern power system and the increasing in the number of power cable lines change the electrical parameters of the traditional power grid composed of overhead lines,and result in variations in the overvoltage distribution along power lines.Therefore,it is of great significance to detect the over-voltage signal of a cable line accurately for its safe and stable operation.Cables are usually buried underground or underseas,with limited space.The structure of a traditional voltage transformer is complex and large,besides,its high frequency response is poor;meanwhile high voltage divider requires strict environmental requirements and its performance is easily affected by stray parameters.Thus they are not suitable for field detection in power system.In order to accurately detect the over-voltage on cable lines,a new method for detecting the over-voltage on cable lines is proposed in this paper.Firstly,the characteristics of cable overvoltage are analyzed,and the structure and principle of the cable overvoltage detection device proposed are introduced in details.According to the principle of the cable overvoltage sensor,the equivalent circuit model is developed and the electrical parameters of the power cable are extracted.The proposed equivalent circuit model of the sensor takes into account the influence of stray parameters of the cable conductor.The factors of output characteristicss and frequency response characteristics of cable overvoltage sensor are analyzed via simulation experiments.In order to eliminate the degradation of the output signal of the cable overvoltage sensor,an adaptive filtering and deconvolution signal recovery combined algorithm is used in this paper.The principle of deconvolution is analyzed,a noise reduction method based on recursive least squares adaptive filter is proposed to reduce the noise in sensor output signal.Considering the facts that in a traditional incremental Wiener deconvolution algorithm the filter parameter is often estimated manually,and the filter parameters have a significant impact on the deconvolution results and the computation cost,an improved Wiener deconvolution algorithm is proposed.The numerical results show that the algorithm is more accurate than the traditional Wiener deconvolution algorithm.An experimental platform for square wave response of cable overvoltage sensor is constructed,and the accuracy of the proposed cable overvoltage sensor equivalent circuit model is validated by experiments.The recovery of the experimental waveform verifies the effectiveness of the proposed signal recovery algorithm.Finally,the short-circuit over-voltage experiment of the cable line demonstrates that the detection method which combines the cable over-voltage sensor with the signal recovery algorithm meets the requirements of the actual field measurement.