双馈风电场次同步控制相互作用仿真研究

Simulation Study on Sub-synchronous Control Interaction of a DFIG-based Wind Farm

首先,建立双馈感应风机包括其控制器的数学模型;然后分析风机并网次同步控制相互作用(sub-synchronous control interaction,SSCI)的产生机理和动态过程。在RTDS(real time digital simulator)软件中搭建单台额定功率为2.2 MW的双馈感应风机发电系统,通过对风机与电网相连线路的电流进行傅里叶分析,得到系统发生次同步振荡时的频率分布特性;通过对风机有功、无功出力的仿真,探讨风速、线路串联补偿度、风电场并列运行风机台数、转子侧变流器(rotor side converter,RSC)及电网侧变流器(grid-side converter,GSC)的控制参数对次同步控制相互作用的影响;风速和风电场风机台数的减小、串联补偿度的提高都会增强次同步控制相互作用,并迅速导致功率的振荡发散,同时控制器PI参数的变化也会对这种作用产生影响。

A doubly-fed induction generator’s （DFIG） mathematical model including its controller is established firstly, then the mechanism and dynamic process of sub-synchronous control interaction （SSCI） when wind power generation connects to the grid are analyzed. The doubly-fed induction generator system is built in RTDS and each generator’s rated power is 2.2 MW, and through Fourier analysis on the current of the line connecting DFIGs and power grid, the frequency distribution characteristics when sub-synchronous oscillation occurs in the system are obtained. Through simulating the active and reactive power output of DFIGs, different effects of wind speed, series compensation level, the number of the DFIGs, the control parameters of rotor side converter （RSC） and grid-side converter （GSC） on sub-synchronous control interaction are discussed. It is shown that the decrease of wind speed and the number of DFIGs and the increased series compensation level will enhance SSCI, which will rapidly lead to growing oscillation. And the change of controller’s PI parameters will also affect this interaction.