双端直流配电网反时限电流方差保护方案

Inverse Time Current Variance Protection Scheme for Two-Terminal DC Distribution System

电力电子技术的进步推动了直流配电技术的发展,但相较于交流配电网成熟的继电保护技术,直流配电网保护面临着速动性不足,传统保护方案不适用等一系列的挑战。因此,该文提出适用于双端直流配电网的反时限电流方差保护,以电流方差代替电流值作为故障判据,并利用电压加速因子加快故障切除,针对两侧保护装置整定值不一致可能导致保护误动的问题,引入电流微分方向判据,实现保护动作的选择性。该方法基于本地测量量,无需通信,动作速度快。

Progress in power electronic technology promotes development of DC distribution technology. However, compared to mature AC relay protection, DC distribution protection faces a series of challenges, such as lack of quickness, inapplicability of traditional scheme, etc. This paper presented an inverse time current variance protection scheme for two-terminal DC distribution system, using current variance instead of over-current as fault criteria and voltage acceleration factor to speed up fault clearance. To solve the problem that inconformity of two sides of protection equipment may cause malfunction of protection, the paper introduced current derivative as direction criteria to realize selectivity of protection. This scheme was based on local measurement and cleared fault without communication. Finally, validity of the proposed protection scheme was verified with PSCAD/EMTDC simulation.