正序电压极化阻抗继电器的保护失效边界模型

Protection failure boundary model of impedance relay with positive-sequence voltage polarization

提出一组以故障距离和过渡电阻大小为核心因子的保护失效边界模型,用以评估阻抗继电器的耐受过渡电阻能力,同时用于探讨阻抗继电器因过渡电阻而拒动和误动的真实原因。重点分析正序电压极化的阻抗继电器,其具有保护区稳定、耐受过渡电阻能力强等优点。定义了能够使继电器正确动作的最大耐受过渡电阻值为保护失效边界电阻。根据保护失效边界模型计算出保护失效边界电阻值和相应的故障距离,用以绘制保护失效边界电阻曲线,再引入保护失效系数的概念,以此评估该继电器的耐受过渡电阻能力以及抗风险能力。PSCAD仿真结果表明,该模型可准确计算出继电器能承受的最大过渡电阻数值。

A set of protection failure boundary model with the fauh distance and transition resistance size as its core factors is proposed to evaluate the transition resistance toleration of impedance relay and investigate its improper operation due to the transition resistance. The impedance relay with positive- sequence voltage polarization is explicitly analyzed,which has stable protection zone and excellent toleration for transition resistance. The maximum transition resistance that the relay can tolerate is defined as the protection failure boundary resistance. The protection failure boundary resistance and corresponding fault distance are calculated based on the protection failure boundary model to draw the curve of protection failure boundary resistance. The concept of protection failure coefficient is introduced to assess the toleration for transition resistance and risk. Results of PSCAD simulation show the proposed model can precisely figure out the maximal transition resistance a relay can tolerate.