基于单周期控制的LCL并网逆变器控制策略研究

A Control Strategy of Grid-Connected Inverter with LCL Filter Based on One-Cycle Control

采用单周期数字控制技术以提高LCL型并网逆变器对电压源侧输入扰动的抑制能力和系统的动态响应,以电容电流反馈作为内环、入网电流反馈作为外环的双闭环反馈控制为系统的主要结构。其中,单周期控制采用双极性算法,对内环输出信号进行逆变器开关管占空比的调制,内环在反馈通道使用比例控制,外环在前向通道使用比例积分控制。分析了以电容电流反馈构建的陷波器抑制LCL谐振的原理,并设计滤波器及控制器参数。通过MATLAB/Simulink仿真平台,建立了LCL型滤波的逆变器并网模型,仿真分析证明了该策略的可行性。

A digital one-cycle control （OCC） technology was adopted to improve the control perforrmnce of gridconnected inverter with LCL filter which could inhabit the input disturbance of voltage source and improve the system dynamic response. The dual closed-loop feedback control was implemented with the inner loop of capacitor current and the outer loop of grid-tied current. Moreover, an OCC bipolar control algorithm was analyzed and designed to modulate the duty cycle signals of the inverter switches from the inner loop output signals. Proportional （P） control at the feedback channel of the inner loop and Proportional-integral （PI） control at the forward channel of the outer loop were adopted in proposed system. The principle was analyzed rrmthematically that a trap filter formed by capacitor current feedback restrained LCL resonance and the paran^ters of filters and controllers was designed. On the basis of MATLAB/Simulink platform, a model of grid-connected inverter with LCL filter was established and the results of simulation were analyzed to verify feasibility of the strategy.