基于故障分量的微电网保护适用性

微电网具有潮流双向流动、并网孤岛运行时故障电流差别大以及拓扑结构灵活多变的特点,给微电网的保护带来了很大的挑战。基于故障分量原理的保护相较于其余的保护方法具有明显的优势,但微电网中的大多数微电源经逆变器接入电网,其故障特性主要受控制策略影响,不同于传统的同步发电机,现有的故障分量分析方法已不再适用。因此,分析故障分量保护在含逆变型分布式电源(IIDG)的微电网中的适用性十分必要。文中主要针对IIDG在恒功率控制策略下的等效模型,建立含多个IIDG的微电网故障附加网络,比较同一母线上的故障线路与其余馈线的正序电流故障分量,从幅值和相位两个角度对故障分量原理进行了分析,并在PSCAD软件中对微电网模型进行了仿真,验证了分析的正确性。

Adaptability of Microgrid Protection Based on Fault Components

Microgrids have many new characteristics, such as bi-directional current, different fault current amplitudes when operating in grid-connected and islanded modes, flexible structures and so on, which challenge microgrid protection. Despite the evident advantages over other protective methods based on the fault component principle, as most distributed generators are connected to the grid through an inverter, their fault features are mainly influenced by the control strategy and obviously differ from traditional synchronous generators. Thus the existing analytic method of fault components is no longer applicable, which makes it imperative to study the adaptability of fault component protection to microgrids with inverter interfaced distributed generators(IIDGs). In this paper, aimed at the equivalent model of IIDG under PQ control, an additional fault network of microgrid including IIDGs is built. Then by comparing the fault component of positive sequence current in the fault feeder with those in other feeders of the same bus, the fault component principle is analyzed from the perspective of amplitude and phase. Finally, the effectiveness of the proposed analytic method is evaluated through microgrid simulation in the PSCAD software environment. This work is supported by National Nature Science Foundation of China(No. 51407128)and Shanghai Science and Technology Committee(No. 12ZR1451300).