基于动态电压恢复器的低电压穿越控制技术研究

Research on low voltage ride through control technology based on DVR

大规模风电接入电网给电网安全运行和管理带来了较大的挑战,新的电网导则要求风电机组应保证具备低电压穿越能力。考虑到动态电压恢复器(Dynamic Voltage Restorer,DVR)具有在短时间内快速准确进行电压补偿的优势,提出了基于动态电压恢复器的风电机组低电压穿越方案。针对DVR中滤波器带来的检测延时和衰减,采用基于瞬时无功功率理论的积分检测法,降低滤波器带来的延迟和衰减。根据DVR的控制特性,提出一种基于坐标变换的双Q-P理论的DVR控制算法,该算法可以补偿瞬时电压扰动,并且能有效改善动态电压恢复器的补偿性能。利用PSCAD/EMTDC仿真软件建立仿真模型,仿真结果表明,电网发生短路故障时,DVR能快速检测电压变化并且准确补偿所需电压,获得理想的瞬态特性,协助改善风电机组的低电压穿越性能。

Large scale wind power integration has brought great challenges to the safe operation and management of power grid.The new power grid guidelines require that wind turbines should have the ability of low voltage ride through(LVRT).Considering that the dynamic voltage restorer(DVR)has the advantages of fast and accurate voltage compensation in a short time,this paper proposes a low voltage ride through scheme for DFIG based on DVR.Aiming at the detection delay and attenuation caused by the filter in DVR,the integral detection method based on instantaneous reactive power theory is adopted to reduce the delay and attenuation.According to the control characteristics of DVR,a DVR control algorithm based on double Q-P theory of coordinate transformation is proposed.The algorithm can compensate the instantaneous voltage disturbance and effectively improve the compensation performance of DVR.The simulation model is established by PSCAD/EMTDC simulation software.The simulation results show that when a short-circuit fault occurs in power grid,the DVR can detect voltage changes quickly and compensate the required voltage accurately to obtain ideal transient characteristics,thereby improving the low voltage ride through performance of the wind turbine.