基于暂态电压比原理的直流配电网故障保护方案

由于直流配电网故障时短路电流呈现上升快、峰值大、过程短的基本特点,给故障的可靠识别和快速切除造成了困难。利用线路出口限流电抗器两侧电压的时域特性实现区内、外故障的可靠判别,提出了一种适用于直流配电网线路的继电保护方案,并通过单侧电气量保护与双侧电气量保护的配合实现了直流配电线路保护的速动性和选择性。该方案仅通过限流电抗器的暂态电压比即可实现对故障的快速检测、识别,不仅能满足直流电网对保护的要求,而且保护方案简单、易实现。大量仿真实例验证了保护方案的可行性,且具备较强的抗过渡电阻能力。

Fault protection scheme for DC distribution network based on ratio of transient voltage principle

Because the short circuit current of DC distribution network has the basic characteristics of rapid rising, high peak value and short process, it is difficult to identify and remove faults reliably and quickly. The reliable identification of internal and external faults is realized based on the time domain characteristics of the voltage on both sides of the current limiting reactor at the line outlet, a relay protection scheme suitable for DC distribution lines is proposed, and the fast-moving and selectivity of DC distribution line protection is realized through the combination of single-terminal electrical quantity protection and double-terminal electrical quantity protection. The proposed scheme can detect and identify faults quickly only through the ratio of transient voltage of current limiting reactor. It can not only meet the protection requirements of DC power grid, but also make the protection scheme simple and easy to implement. A large number of simulation examples verify the feasibility of the protection scheme, and it has strong ability against transition resistance.