分布式电源短路计算模型及电网故障计算方法研究

分布式电源的发电模式及并网方式多样,其馈入电网的故障电流特性与传统交流同步发电机相比存在较大差异,使以传统交流同步电机供电电源为基础的短路电流分析理论和方法难以满足分布式电源接入后电网故障分析的要求,给继电保护原理研究和整定计算提出了新的课题并备受关注。根据不同类型分布式电源的低压穿越运行技术要求,建立逆变型电源的短路计算模型。并考虑异步型电源撬棒保护的动作行为特征,建立了异步型电源在电网严重和非严重故障条件下的等值计算模型。进而,提出了含分布式电源接入的电网故障计算方法。仿真对比分析表明,电网故障计算方法精度较高,能更好地满足工程应用要求。

Study on short-circuit calculation model of distributed generators and fault analysis method of power system with distributed generators

The power generation modes and grid connected strategies of DGs are diversified, and the transient and steady-state characteristics of the fault currents provided by DGs are much different from those of the fault currents provided by conventional synchronous generator. The special fault current characteristics of DGs make the conventional fault analysis method can be no more applied for the power grid with penetration of DGs. It is a new topic for the principle and setting calculation of the relay protection. According to the low voltage ride through (LVRT) control strategy of the corresponding DGs, the short-circuit calculation model of inverter interfaced distributed generator (IIDG) is established. Then, under serious and non-serious fault conditions, the short-circuit calculation models of doubly-fed induction generator (DFIG) are proposed based on the behavior characteristic of the crowbar. Based on this, a novel fault analysis method of power system with DGs is proposed. The simulation results show that the proposed method has a high accuracy of short-circuit current calculation and can meet the requirements of engineering application.