【摘要】 储能电容器的工作过程是在高压直流条件下较长时间的充电后在很短的时间放电,从而在负载上形成高电压、大电流的脉冲,这种脉冲电流是电容器绝缘老化的主要原因。为了检测该电容器的性能,开发了一套在高压直流条件下进行储能电容器局部放电检测的装置,并给出了初步试验结果。为提高大电容测量系统的灵敏度,采用并联RLC型电桥平衡回路提取放电信号,并经窄带、增益稳定的放大单元和带通滤波器、数据采集卡得到试验数据。试验表明,该系统可获得不同缺陷电容器发生局部放电时放电幅值的时间分布谱图。利用Delta(t)方法进行统计分析,可提取到不同缺陷的Qmax-Δt-、Q-Δt、n-Δt和n-Q曲线,这为直流局部放电的统计分析和模式识别、判断故障类型和介质老化程度打下了良好的基础。更多还原

【Abstract】 High voltage(HV) storage capacitor is widely used in pulse power equipments.When it works,it is charged under DC source in a long time and discharges at a high voltage and large current pulse in a very short time.This pulse is the main reason to induce the capacitor aging.In order to test the performance of the capacitor,a suit of HVDC partial discharge(PD) detecting instrument was developed,the optimum bandwidth of which is about 64～257kHz based on the parameters of the defects,and the results of the preliminary experiments were gained.In order to increase the sensitivity of measurement system for large capacitance,the RLC balanced detection circuit was used to pick-up the DC PD.After being amplified by a narrowband,gain-stable differential amplifier and filtered by a band-pass filter,these PD signals were sent to the sampling software by an acquisition card.Through the experiments,the magnitudes of PD over time in different capacitors were got.After statistic analyzed by application of the Delta(t) method,the Qmax-Δt,mean-Δt,n-Δt and n-Q curves related to DC PD were extracted.For the different characters of the statistic graphs,all kinds of defects can be clearly distinguished from these curves and the causes of the differences between these curves are preliminary analyzed.These results would be further used to the statistic analysis of DC PD,which were the base to recognize the PD patterns and to determine fault types and aging degree.In order to test the performance of a capacitor,a suit of HVDC partial discharge(PD) detecting instrument was developed,the optimum bandwidth of which is about 64～257kHz based on the parameters of the defects,and the results of the preliminary experiments were gained.In order to increase the sensitivity of measurement system for large capacitance,the RLC balanced detection circuit was used to pick-up the DC PD.After being amplified by a narrowband,gain-stable differential amplifier and filtered by a band-pass filter,these PD signals were sent to the sampling software by an acquisition card.Through the experiments,the magnitudes of PD over time in different capacitors were abtained.After statistically analyzing the application of the Delta(t) method,the Qmax-Δt,-Δt,n-Δt and n-Q curves related to DC PD were extracted.For the different characters of the statistic graphs,all kinds of defects can be clearly distinguished from these curves and the causes of the differences between these curves are preliminary analyzed.These results would be further used to the statistic analysis of DC PD,which were the base to recognize the PD patterns and to determine fault types and aging degree.更多还原