园区直流微电网的故障分析及保护配置方案研究

首先，基于园区直流微电网的构成和特点，分析了不同接地方式的故障特性及其对故障检测装置的要求，并推导了故障电压、电流响应曲线。其次，根据电力电子变压器拓扑结构，证明欠阻尼条件下电流不存在振荡问题。再次，对采取保护配置方案前后的短路电流进行对比，同时考虑故障时设备安全及保护配合等因素，给出了保护配置方案的约束条件。最后，基于PSCAD/EMTDC平台搭建园区直流微电网模型，对所提方案进行了仿真验证。结果表明：采取保护配置方案后短路电流明显下降，电流持续时间变长，根据保护装置参考条件所得的参数值满足故障电流检测与保护判断所需时间。

Fault Analysis and Protection Allocation Research of Park DC Microgrid

Based on the structure and characteristics of park DC micro-grid system, the fault characteristics of different grounding modes and the requirements for fault detection devices are analyzed in this paper, and the response curve of voltage and current is deduced. Based on the topological structure of power electronic transformer, it is proved that the current has no oscillation problem under the condition of under damping. And then, the short-circuit currents before and after installing protection allocation scheme are compared, and the constraint conditions for selection of protection allocation scheme are given with consideration of such factors as equipment safety and protection coordination in case of faults. Finally, a park DC microgrid model is constructed based on the PSCAD/EMTDC platform, and a simulation is made on the proposed scheme. The simulation results indicate that:the short-circuit current decreases significantly after installing protection allocation scheme, while the current response time increases; and the parameter value obtained according to the reference condition for protection device selection satisfies the time required for fault current detection and protection judgment.