海上风电直流输电系统断线故障保护及恢复策略

A Fault Protection Strategy and Restorative Strategy for DC System Incorporating Offshore Wind Farm Under Open DC Line Fault

基于一种适用于海上风电传输的双极性直流输电系统拓扑结构,详细介绍了其关键设备及控制模式,分析了该直流输电系统在永久性直流断线故障时的故障特性。为抑制故障引起的过电压现象,采用一种将闭锁电压源型换流器(voltage source converter,VSC)与断开直流开关相互配合的故障保护策略,保护系统中的关键设备,使系统快速、安全地实现故障隔离;故障清除之后,需要对系统进行恢复控制,提出一种并行恢复策略,使系统停运设备可以快速、平稳地恢复正常运行。在PSCAD/EMTDCTM环境下搭建了系统的仿真模型,通过仿真验证所提出的故障保护策略及故障恢复策略的可行性。

Based on a simplified bipolar DC system topology for offshore wind power transmission, corresponding key components and control strategies are discussed in detail. Firstly, this paper analyses fault characteristics of the DC system under permanent open DC line fault. A fault protection strategy combining DC switch action and voltage source converter （VSC） blocking is proposed to restrain post-fanlt overvoltage and protect the devices near fault position so that the fault can be isolated from the system quickly and safely. The system needs to restore after fault clearance. This paper proposes a parallel restorative control strategy to restart outage devices of the system quickly and smoothly. Simulation model of the system is built under PSCAD/EMTDCTM environment. Simulation results demonstrate feasibility and validity of the proposed fault protection strategy and restorative control strategy.