光伏并网逆变器模型预测电流控制研究

摘要

在αβ两相静止坐标下建立逆变器输出电流的预测模型，通过评估函数对逆变器输出的不同电压矢量进行最优选择，预测函数计算出下一时刻可能的输出值。当评估函数取值最小时，对应的电压矢量为最优，采用此时的开关状态对逆变器进行控制，实现并网电流快速跟踪参考电流。该控制方法无需脉冲宽度调制信号，通过单次坐标变换，避免了复杂的运算过程，降低了控制偏差。仿真结果表明当参考电流动态变化时，模型预测电流控制能快速跟踪参考电流变化。当光伏电池的光照强度变化时，模型预测电流控制能快速追踪光伏电池最大输出功率点，且逆变器输出电流谐波畸变低。通过对比传统空间矢量脉宽调制控制下的输出波形，验证了模型预测电流控制策略的有效性。%Through coordinate transformation , the predictive model of the inverter output currents is proposed in the two-phase static αβ-frame.The cost function is used to assess different voltage vectors of the inverter and predict all possible output currents .The voltage vector which minimizes the cost function is selected , and then the corresponding switching state is applied in the next sampling time to track reference currents quickly .The proposed strategy needn't to use the traditional PWM modulator .Only once coordinate transformation is needed to calculate the optimal switching state, so the strategy has small amount of calculation and easy to be implemented .Simulation results indicate hat if reference currents change dynamically , the model predictive current control can track reference currentsquickly .Ifthe light intensity changes ,the model predictive current controlcan track the maximum power point rapidly and the inverter output currentshave low harmonic distortion .The simulation results verify the effectiveness of the proposed control strat-egyby comparing the output waveformunder SVPWM control .