基于特征值分析的DFIG风电机组在微电网中的频率控制策略研究

Control Strategy of DFIG Wind Power Generation on Frequency Control of Micro-grid Based on Eigenvalue Analysis

随着电力电子技术的发展,变速恒频DFIG风电机组可通过虚拟惯量控制和超速控制减载运行参与电网频率调整。针对含DFIG风电机组的风光柴中压微电网,采用特征值分析方法,分析DFIG风电机组虚拟惯量控制、超速控制和柴油机调速器控制参数变化时微电网的特征值轨迹,找出反映微电网频率响应特性的典型特征值。并通过分析不同虚拟惯量控制和超速控制参数对应的典型特征值变化轨迹,判断微电网频率稳定性的变化,得到虚拟惯量控制和超速控制参数合理选取范围。为改善频率控制参数选取过大产生的频率振荡问题,进一步改进DFIG风电机组有功功率控制系统PI控制参数,从而在改善微电网频率动态响应特性的基础上提高了微电网小干扰稳定性。最后,在DIg SILENT/Power Factory仿真软件中搭建微电网模型,通过动态时域仿真验证所提方法对提高微电网频率稳定性和小干扰稳定性的有效性。

With developing of power electronics technology, the variable speed constant frequency doubly fed induction generator （DFIG） could be involved in frequency adjustment by using virtual inertia control and over-speed load reduction control. This paper focus on finding the eigenvalue of response character of frequency of micro-grid, which is achieved by analyzing the variation of the eigenvalues of the micro-grid when the parameters of the virtual inertia control, over-speed control and diesel engine control changes. The reasonable range of the variation of the virtual inertia control and over-speed control was obtained by taking the stability of the micro-grid into consideration. The stability of the micro-grid was evaluated by the variation of the eigenvalue of the micro-grid corresponding to the variation of parameters of the virtual inertia control and the over-speed control. To solve the frequency oscillation problem caused by choosing too big frequency control parameters, the PI parameters of the active power control of the DFIG was modified, so that the small signal stability of the micro-grid is improved by improving dynamic response of the frequency of the micro-grid. Finally, the method, which could improve the frequency stability and the small signal stability of the micro-grid, proposed in this paper was verified by dynamic time-domain simulation that was built in DIgSILENT/PowerFactory.