电网故障下光伏并网低压故障穿越控制策略的研究

电网发生故障或扰动可能造成光伏并网点电压跌落，严重影响电力系统的安全运行，光伏发电站有必要具备在电压跌落范围和时间内保证不脱网运行的能力。提出一种基于无功补偿的光伏并网低压穿越控制策略。该方法在检测到电压跌落时，通过断开外部电压环路将双闭环控制模式更改为单电流环路操作模式，采用改进后的无功补偿控制策略防止逆变器产生过电流，为电网电压提供无功补偿，较好实现不脱网运行。最后利用Matlab / Simulink软件比较和分析低压穿越控制策略前后的相关参数。仿真结果表明，改进的控制策略可以有效地抑制逆变器输出电流的增加，并且能提供无功功率来支持电网电压，以在电网电压骤降期间实现低压穿越。

Control Strategy of Photovoltaic Grid-connected Low-voltage Fault Ride-through under Power Grid Fault

Power grid failure or disturbance may cause voltage sag of photovoltaic connection point， which seriously affects the safe operation of power system. Photovoltaic power stations should have the ability to ride through in the range and time of voltage sag. A low voltage ride through （LVRT）control strategy based on reactive power compensation is proposed. When the voltage sag is detected with this method， the double closed-loop control mode is changed to the single current loop operation mode by disconnecting the external voltage loop. The improved reactive power compensation control strategy is adopted to prevent the inverter from generating overcurrent and provide reactive power compensation for the power grid voltage to realize ride through. Matlab/Simulink software is used to compare and analyze the related electrical parameters before and after LVRT control strategy. Simulation results show that the improved control strategy can effectively restrain the increase of the output current of the inverter， provide reactive power to support grid voltage， and realize low voltage ride through during the grid voltage sags.