基于柔直电网的暂态量保护方案及配合策略研究

柔直电网中直流线路故障的检测和隔离是一个亟待解决的问题。针对柔直电网的基本架构,在分析直流线路故障对直流线路保护的需求的基础上,引入了基于边界原理的暂态量保护,并进行了适用性分析。通过分析发生直流线路故障时快速跳开直流线路两端的直流断路器必要性,提出在提高测量采样频率和优化判据时间窗的基础上,根据故障反行波能量和前行波能量在功率送端站和受端站的不同特征,对暂态量保护判据进行优化,并给出了直流线路两端配置的保护方案。在此基础上,进一步研究了暂态量保护与直流断路器、直流母线保护相配合的故障清除策略。通过仿真验证了所提策略的可行性。

Study on transient-based protection scheme and cooperation strategy based on flexible DC grid

The detection and isolation of DC line faults is an urgent problem to be solved in flexible DC grid. In this paper, based on the basic structure of flexible DC grid, by analyzing the DC line fault protection requirements for DC line protection, a transient-based protection based on boundary principle is introduced, and applicability analysis is performed. It analyzes the necessity of quickly tripping the DC circuit breakers at both ends of the DC line when a DC line fault occurs. Then on the basis of improving the measurement sampling frequency and the optimization criterion time window and according to the different characteristics of the fault reverse wave energy and the forward wave energy at the power delivery converter station and the receiver station, it optimizes transient-based protection criterion and provides a protection scheme for the both ends of the DC line. On this basis, it further researches the fault clearing strategy of DC link transient-based protection cooperation with DC circuit breaker and DC bus protection. The feasibility of the proposed strategy is verified by simulation. This work is supported byKey Project of Smart Grid Technology and Equipment of National Key Research and Development Program of China (No. 2016YFB0900600) and Science and Technology Project of State Grid Corporation of China (No. 52094017000W).