考虑负荷的大规模DG系统的建模与同步稳定性

Modeling and Synchronization Stability of Large-scale Distributed Generation System Considering Load

随着分布式发电系统的发展,可再生能源并网呈现低密度和大规模的趋势,给电力系统带来了同步稳定性的挑战。为了研究在大规模分布式发电系统并网情况下的电力系统同步稳定性,本文以带节点负荷的非均匀大规模分布式发电系统为对象,首先结合下垂控制和Kuramoto模型推导了该系统的数学模型,并基于此模型推导出系统节点锁相的必要条件;然后利用?ojasiewicz不等式判断系统收敛到同步稳定点的速率。为了验证理论结果的有效性,基于实例低压配电网络构造出带有节点负荷的3种基本网络,并设计了一个低压微电网系统。仿真结果表明,星形网络同步稳定性最优,且同步结果与理论分析相符。

With the development of distributed generation(DG)systems,grid-connected renewable energy is showing a trend of low density and large-scale,which brings challenges to the synchronization stability of power system. To study the synchronization stability of power system when a large-scale DG system is connected to the power grid,a nonuniform large-scale DG system with node load is taken as the object in this paper. First,a mathematical model is derived with the combination of droop control and the Kuramoto model,based on which the necessary conditions for system node phase lock are formulated. Then,the Lojasiewicz inequality is used to judge the rate at which the system converges to a stable point of synchronization. To verify the validity of theoretical results,three basic networks with node loads are constructed based on an example of low-voltage distribution network,and a low-voltage microgrid system is designed. Simulation results show that the synchronization stability of the star network is optimal,and the synchronization results are consistent with the theoretical analysis.