基于控保协同的多端柔性直流配网故障测距方法

Fault Location Method for Multi-terminal Flexible DC Distribution Network Based on Control and Protection Coordination

柔性直流配电网故障电流冲击大、危害严重,通过改变柔性直流配电网中可控元件的控制策略,可以改变故障特性,进而为故障保护与测距提供支持。为此,提出基于控保协同的多端柔性直流配电网故障测距方法。首先,以四端柔性直流配电网为例,分析配电网的故障特性与限流特性。其次,研究柔性配电网中的关键设备限流电抗器对直流配电网故障特性的影响,并基于此提出直流配电网两阶段控保协同策略。在控保协同第I阶段中,利用限流电抗器的限流特性抑制故障电流发展,辅助故障隔离;在控保协同第II阶段中,控制限流电抗器通断策略,通过短暂重合闸向直流配电网注入可控小电流,进行故障测距。最后,搭建含光/储的四端柔性直流配电网仿真模型,验证所提方法的有效性。

The fault current of the flexible DC distribution network has a large impact and serious harm.By changing the control strategy of the controllable elements in the flexible DC distribution network,the fault characteristics can be changed,thereby providing support for fault protection and ranging.Therefore,this paper proposes a fault location meth-od for multi-terminal flexible DC distribution network based on the coordination of control and protection.Firstly,a four-terminal flexible DC distribution network is taken as an example,and the fault characteristics and current limiting characteristics of the distribution network are analyzed.Secondly,the influence of the key equipment current-limiting re-actor in the flexible distribution network on the fault characteristics of the DC distribution network is studied,and thereby,a two-stage control and protection coordination strategy for the DC distribution network is proposed.In the first stage of the coordination of control and protection,the current-limiting characteristics of the current-limiting reactor are used to suppress the development of the fault current and assist the fault isolation;In the second stage of the coordination of con-trol and protection,the on-off strategy of the current-limiting reactor is controlled,a small controllable current is injected into the DC distribution network through short-term reclosing,and fault location is carried out.Finally,a four-terminal flexible DC distribution network simulation model with photovoltaic/storage is built to verify the effectiveness of the proposed method.