一种数字化冲击电压波形重构新算法

New Algorithm for Reconstruction of Digital High Voltage Impulse Waveform

为减少数字化冲击测量系统的测量误差,分析了冲击电压经数字化冲击测量系统后被测波形产生畸变的原因;提出了一种利用离散Gabor变换展开去噪与增量维纳滤波器相结合的冲击电压波形重构算法。IEC1083-2测试数据发生器产生的波形信号的研究表明,该法可有效去除噪声,波形复原准确度和稳定性较高。

It is very important to accurately measure the wave form of fast transient voltage in high voltage apparatus experiments and elementary researching field of insulation materials. In ideal circumstance, the fast transient measured by a voltage divider system will be a wave form without any distortion, but merely a sampling sequence in digital sampling module whose extent value is divided according to the divider ratio. However, in the application of practical measurement, due to the poor quality of transient response of voltage divider system, the measured waveform of fast transient will be distorted after passing through the voltage divider system. The distortion of waveform caused by the poor quality of transient response of voltage divider system will be more serious when front chop impulse and steep-front impulse ismeasured. At the same time, the quantization noise which is produced by the digital sampling module of measured impulse wave form will greatly affect the exact measurement of the peak value of voltage and all time parameters will appear great inaccuracy. The reason why digital impulse voltage measuring system introduces some distortion in measured input impulse voltage waveform is analyzed. A new algorithm method, which uses noise reduction technique based on discrete Gabor expansion and incremental Wiener filter to achieve reconstruction of digital high voltage impulse waveform, is presented in this paper. It is noticed that there is different feature between the Gabor coefficient of fast transient and noise distribution in the time-frequency domain, the Gabor series method is presented for denoising the impulse signal embedded in noise. In order to recover the fast transient distorted by oscillation on the test circuit, this paper analyze the theory of deconvolution and present an incremental Wiener filter to perform reconstruction of digital high voltage impulse waveforrn. To verify the effectiveness of this algorithm, simulated waveforms obtained from IEC1083-2 TDG （test data generator） is calculated by this method. Calculation results show that this algorithm can denoise effectively and approaches high accuracy and stability, satisfying the needs of reconstruction of digital high voltage impulse waveform.