高压电网接地电位差干扰信号滤波算法研究

Research on filtering algorithm for the grounding potential difference interference signals in a high voltage power grid

在电力高压站高压隔离开关动作时,产生的特快速暂态过电压(very fast transient overvoltage,VFTO)耦合到二次电缆传输信号中,会造成测量的不准确和设备的误动作。以提高继电保护抗干扰能力为目的,建立并分析“接地网-二次电缆-智能组件”的耦合路径,根据电力系统理想采样点的信号特征,提出应对接地网电位差干扰的算法,采用启动元件和判定元件快速判断采样值是否为干扰信号,根据高压隔离开关动作引起的接地网电位差干扰信号幅值高、上升时间短和频带范围宽的暂态特性,采用小波变换作为滤波算法。仿真实验结果表明,此滤波算法能够有效地滤除隔离开关动作引起的接地网电位差干扰信号,均方根误差减少91.6%,信噪比提高138.5%,保证了继电保护数据测量的准确性,提高了电力系统继电保护的可靠性。

When the disconnector is operated in a high-voltage substation,the very fast transient overvoltage(VFTO)could be coupled to the transmission signals of the secondary cable,causing inaccuracy of the measurement and misoperation of the equipment.In order to improve the anti-interference ability of relay protection,the coupling path of the"grounding grid–secondary cable–intelligent component"is established and analyzed.An algorithm to deal with the interference signals caused by the grounding grid potential difference is proposed according to the characteristics of the ideal sampling signals in the power system,with the starting element and decision element judging the signal state quickly.The wavelet transform is used as the filtering algorithm to cope with the high amplitude,short rise time and wide bandwidth of the interference signals caused by the disconnector operation.The simulation results show that this filtering algorithm can effectively remove the disturbance signals caused by grounding grid potential difference,with an advantage of 91.6%reduction of the root mean square error and 138.5%improvement of the signal to noise ratio.With it,the accuracy of measured data of relay protection is ensured and the reliability of power system relay protection is improved.