直流微电网中电压源型变流器故障穿越控保协同策略

Control and Protection Cooperation Strategy for a Voltage Source Converter in a DC Microgrid During a Fault Ride-through

目前,直流微电网的保护方案主要是基于传统保护思想,由于直流故障时冲击电流大、上升速度快,可供使用的数据信息极少,导致对保护装置的快速检测和开断能力要求较高,大幅增加了系统的建设运行成本。以典型直流微电网为研究对象,深入分析了AC/DC、DC/DC等电压源型变流器的故障特性,提出了一种具备直流故障穿越能力的电压源型变流器控保协同策略,通过设计通用的直流故障穿越模块,能够在故障发生时快速隔离故障,并主动输出稳定可控的短路电流,以降低保护检测难度;同时,该附加模块还能自动诊断外部故障清除情况,以快速恢复系统运行。最后通过仿真验证了所提控保协同策略的有效性。

The current protection scheme for DC microgrids is mainly based on the traditional protection strategy.Because of the large and rapid rising impact current during a DC fault,the available data information for protection is quite rare.This has resulted in high requirements for the rapid detection and breaking capability of protection devices,which in turn considerably increases the construction and operation costs of DC microgrids.In this study,based on a typical DC microgrid,the fault characteristics of voltage source converters such as AC/DC and DC/DC are thoroughly analysed.The study then proposes a control and protection cooperation strategy for a voltage source converter in a DC microgrid during a fault ride-through(FRT).This method designs a universal DC FRT module that can realize quick fault isolation and inject a controllable short circuit current during a DC fault,which reduces the difficulty of protection detection.Simultaneously,the DC FRT module can also quickly restore system operation by automatically identifying whether the fault is rectified.Finally,a simulation model is constructed to verify the effectiveness of the proposed control and protection cooperation strategy.