基于限流电抗器电压的柔性直流配电线路单端量保护新方法

A New Method of Single-terminal Protection for Flexible DC Distribution Lines Based on Current-limiting Reactor Voltage

柔性直流配电技术的理论研究已经步入成熟阶段,其线路保护方法的不完备成为制约该技术发展的重要因素,尤其是以快速动作为优势的单端量保护,耐高阻能力弱、所需采样率高等问题仍待解决。为解决上述问题,文中通过分析单极对称接线系统发生金属性双极短路故障和经过渡电阻故障时限流电抗器电压特征,利用限流电抗器电压及其负变化率积聚和构造保护判据,据此提出了一种基于限流电抗器电压的柔性直流配电线路单端量保护新方法。仿真结果表明,该方法能在0.5 ms内可靠识别区内故障,且耐受过渡电阻(20Ω)和噪声影响,所需采样率要求低,具有工程实用意义。

The theoretical research of flexible DC distribution technology has entered a mature stage,and the imperfection of its line protection method has become an important factor restricting the development of this technology,especially the single-terminal protection with the advantage of fast action,which has weak resistance to high resistance and high sampling rate,still needs to be resolved.In order to solve the above problems,a new method of single-terminal protection for flexible DC distribution lines based on the current-limiting reactor voltage is proposed in this paper by analyzing the characteristics of the current-limiting reactor voltage and its negative rate of change in the time limit current reactor voltage when the metal bipolar short circuit fault occurs in the single-pole symmetrical connection system and the transit-resistance fault occurs.The simulation results show that the method can reliably identify faults in the region within 0.5ms,and can withstand the influence of transition resistance(20Ω)and noise,and requires low sampling rate,which is of practical significance in engineering.