基于逆变型DG控制特性的微电网故障特征分析

微电网中含有逆变型分布式电源（DG）,其故障特性直接受DG控制策略的影响,因此传统配电网故障分析方法不适用于微电网。在故障条件下,逆变型分布式电源由于其不同的控制方式,产生较为复杂的故障特性。首先根据含恒功率（PQ）控制、V/F控制的逆变型（DG）输出特性约束方程,构建DG故障特性分析的等值模型;然后利用DG等值模型,建立孤岛运行和并网运行2种运行方式下的微电网故障等值模型,求解其稳态响应;最后,运用电力系统仿真软件DIgSILENT搭建同时含PQ控制和V/F控制的逆变型DG的微电网仿真模型,通过与传统故障分析方法的比较,验证了新方法在不同故障条件、DG控制方式及微电网运行条件下该方法的适应性、有效性及准确性,为微电网保护策略的制定提供准确的判据。

New Microgrid Fault Analysis Method Based on Inverter-Type DG Characteristic

Inverter-type distributed generation output is different from traditional generation during system fault. This results in challenges on fault characteristic analysis and protection schemes of microgrid. The output of inverter-type DG depends on not only microgrid conditions but also control modes. Firstly, new equivalent fault analysis model of microgrid is developed with consideration of PQ control and V/F control constraints. Secondly, Based on equivalent model, DG fault voltage and current under both symmetrical and asymmetrical conditions are determined. Finally, the well-developed power grid simulation software DIgSILENT is used to build microgrid simulation model of inverter-type DG with both PQ control and V/F control functions. The simulation results are compared with results calculated by traditional fault analysis. The comparison results verify the effectiveness and accuracy of proposed fault analysis method.