恒电压控制下DFIG与SVG对电网电压的支撑研究

Research on Grid Voltage Support of DFIG and SVG Under Constant Voltage Control

双馈风机(DFIG)能变速恒频运行,并具有一定的无功输出能力,已成为目前的主流发电机。DFIG虽然具备无功调压能力,但其能力有限,在电网遭受扰动情况下对风电场并网点电压的支撑能力不足。基于此,提出双馈风机采用恒电压控制,在充分利用机组无功调压能力的基础上装设SVG对风电场进行动态无功补偿,支撑风电场并网点电压。在分析双馈风机及SVG的数学模型基础上,采用空间矢量定向控制技术实现双馈风机的解耦控制和SVG输出无功的控制并得到两者的控制模型。根据得到的控制模型建立仿真模型,通过仿真验证了采用恒电压控制的双馈风机具备一定的调压能力,SVG与恒电压控制下的双馈风机相配合使得风机并网点电压在正常及故障下均得到显著改善。

Nowadays,DFIG becomes the current mainstream generator because of its variable speed and constant frequency operation characteristics and the capability of reactive power regulation.Although DFIG has the capability of reactive power regulation,its capacity is limited.Based on this,it was proposed that the doubly-fed wind turbine adopted constant voltage control and made full use of the reactive power voltage regulation capability of the unit to install SVG to dynamically compensate the wind farm and supported the grid-connected point voltage of the wind farm.Based on the analysis of the mathematical model of the doubly-fed fan and SVG,the space vector directional control technology was used to realize the decoupling control of the doubly-fed fan and the control of the SVG output reactive power and obtain the control models of both.According to the control model,the simulation model was established.It was verified by simulation that the doubly-fed fan with constant voltage control had a certain voltage regulation capability.The combination of SVG and the doubly-fed fan under constant voltage control made the grid-connected point voltage of the fan significantly improved both under normal conditions and failures.