基于频率耦合阻抗模型的海上风电并网系统振荡稳定性分析

Analysis on Oscillatory Stability of Offshore Wind Power Grid-connected System Based on Frequency-coupled Impedance Model

海上风电的大规模开发利用可能会引起次(超)同步振荡事故,降低系统的稳定水平,因此亟需一种能准确分析海上风电并网系统振荡稳定性的方法。为此,首先建立设备的频率耦合阻抗模型,根据系统的拓扑结构,形成海上风电并网系统的阻抗网络模型,由网络的传递函数得到系统的聚合阻抗,根据聚合阻抗的频率特性获得系统的振荡模式并判断模式的稳定性。将所提方法应用到某海上风电交流外送系统中,分析系统的次(超)同步振荡风险,研究并网风电机组数量和交流系统强度这2个关键因素对系统次(超)同步振荡的影响规律,并通过仿真验证分析结果的准确性。

The large-scale development and integration of the offshore wind power may cause sub(super-)synchronous oscillation(SSO)issues,which reduces the stability level of the system.Therefore,it is of significance to accurately analyze the oscillatory stability of offshore wind power systems.This paper firstly establishes the frequency-coupled impedance model of the equipment,and then forms the impedance network model(INM)according to the system topology.Through the transfer function matrix,the aggregated impedance of INM is obtained.According to the frequency characteristics of the aggregated impedance,it also obtains the oscillatory modes of the system and judges their stability.It uses the proposed method in an offshore wind power system connected to the AC power grid to analyze the risks of SSOs and studies the influence of numbers of online wind turbines and strengths of the AC system on SSOs.Finally,it verifies the accuracy of the analysis results by EMT simulations.