基于阻抗幅值波动差异的新型参数识别方向元件

Novel parameter identification directional element based on impedance amplitude fluctuation difference

针对故障分量方向元件在大规模双馈风机并网不适用的问题,提出了基于正序阻抗幅值波动差异的新型参数识别方向元件。首先,将风电场正序阻抗波动量化,分析阻抗波动对正序故障分量方向元件影响,得到正序故障分量方向元件在风电场送出线路的拒动边界。其次,基于Prony算法结合带通滤波器提取工频量,分析送出线路风电侧正、反方向故障正序阻抗幅值变化特征。最后,引入去趋势波动分析(detrended fluctuation analysis, DFA)计算波动函数,构造新型参数识别方向元件动作判据,实现故障方向判别。仿真结果表明,提出的参数识别方向元件不受风电场运行工况、故障类型和系统振荡的影响。当过渡电阻达到100Ω时,仍能正确判别故障方向,具有较强的抗干扰性能,适用于含风电接入的弱馈型电力系统。

There is a problem in that the fault component directional element is not suitable for grid-connected large-scale DFIG. Thus a novel parameter identification directional element based on the difference of positive sequence impedance amplitude fluctuation is proposed. First, this paper quantifies the positive sequence impedance fluctuation of a wind farm, analyzes the impact of impedance fluctuation and obtains the rejection boundary of the positive sequence fault component directional element on the wind farm outgoing line. Second, based on the Prony algorithm combined with a band-pass filter, the power frequency is extracted, and the characteristics of the positive sequence impedance amplitude change of the forward and reverse faults on the wind power side of the outgoing line are analyzed. Finally, detrended fluctuation analysis(DFA) is introduced to calculate the fluctuation function, and a novel parameter identification directional element action criterion is constructed to realize the fault direction identification. The simulation results show that the proposed parameter identification directional element is unaffected by the operating conditions of the wind farm, fault types and system oscillations. When the transition resistance reaches 100 Ω, it can still correctly determine the fault direction, has strong anti-interference performance, and is suitable for weak feeder power systems with wind power access.