对CT/CVT断线工况完全免疫的高压线路纵联保护新原理

A Novel Pilot Protection Principle for High-voltage Transmission Line Immune to CT/CVT Line-break Condition

当出现CT/CVT断线工况后,高压线路的所有对应保护必须无条件退出运行,避免由此引起的保护误动。对于仅配置单套保护的线路,将失去主保护,即便CT/CVT与保护均双重化配置,保护系统也将退化为单重状态,可靠性显著降低。分析表明,在任一CT/CVT断线后,仍可借助线路两侧的信息冗余设计具有绝对动作安全性和较高动作灵敏性的保护判据,令高压线路保护CT/CVT断线工况下仍能持续运行,由此必大大增强保护系统的整体可靠性。该文首先借助贝瑞隆模型将线路对端计算得到的本端电压电流信号发送至本端,并与本端采集得到的电压电流信号形成共4组电压、电流信号,基于S变换分别计算4组信号的能量相对熵及相角差,进而提出一种对CT/CVT断线工况完全免疫的线路纵联保护新原理。理论分析及仿真测试表明,提出的保护原理不仅在CT/CVT正常时具有优良的动作性能,在任意CT/CVT断线工况下也能保证保护的正确动作。

All the relay protections of the HV transmission line should cease operation unconditionally under CT/CVT line-break condition to avoid maloperation.For the transmission line equipped with single set of protection,it will lose the main protection.Even if CT/CVT and the protection are double-configured,the protection system will degraded into single-configuration,leading to significant decrease of reliability.Analysis in this paper indicates that when any one of CT/CVT line-break occurs,information redundancy of both sides of the transmission line can still be relied to design the protection criterion with absolute security and high sensitivity of operation,which can help the protection of the HV transmission line continue to operate under CT/CVT line-break condition.In this way,the overall reliability of protection system can be greatly strengthened.by utilizing the Bergeron model,the local voltage and current signals calculated at the opposite side of the line were sent to the local side,thus forming a total of four signal groups with the voltage and current signals sampled at the local side.Based on S-transform,both the energy relative entropy and the phase angle difference of the voltage and current signals were calculated respectively.Subsequently,a novel pilot protection principle with the tolerance capability of CT/CVT line-break condition was proposed.Theoretical analysis and simulation results indicate that the protection principle proposed in this paper not only possesses superior operating characteristics under normal condition,but can ensure the correct operation of protection when any one of CT/CVT line-break occurs.