含逆变型分布式电源配电网的中性点接地电阻选取

Selection of Neutral Grounding Resistance of Distribution Networks Containing Inverter-type Distributed Power Supply

IIDG(逆变型分布式电源)的大量接入使得传统电网的结构发生了巨大的改变,IIDG并网侧变压器中性点接地方式会对系统的故障特性造成一定的影响。当配电网发生故障时,IIDG提供的故障电流与传统发电机相比有较大不同。根据IIDG的运行特性,建立了在非对称故障下短路电流的计算模型,对不同情况下的系统故障电气量进行详细的理论分析,进一步提出接地电阻的阻值选取方案。区域电网实例的数字仿真结果验证了理论分析的正确性以及接地电阻取值方案的实用性。

The massive access of inverter interfaced distributed generation(IIDG)brings about drastic changes in the structure of the traditional power grid. The neutral grounding mode of the transformer on IIDG-integrated side to some extent affects the fault characteristics. In the case of distribution network failure,the fault current from IIDG is quite different from that of traditional generators. According to the operation characteristics of IIDG,the calculation model of short-circuit current under asymmetric fault is established,and the detailed theoretical analysis of the system fault electrical quantities under different conditions is carried out to propose a limit value selection scheme of grounding resistance. The results of digital simulation on regional power grid verify that the theoretical analysis is correct,and the value selection scheme of the grounding resistance is practicable.