基于光伏逆变最大功率约束下垂控制策略研究

光伏逆变系统是基于传统下垂控制方法来实现有功功率的平均分配，但这会造成光伏单元最大功率制约及浪费。因此，为了提升光伏单元输出能量的最优利用率，提出了一种光伏逆变器改进型下垂控制策略。该策略基于变步长的扰动观察法进行光伏电板最大功率的跟踪控制，其最大输出功率约束将生成下垂有功功率补偿量，将其叠加到传统下垂控制有功功率对应频率参考值的修正，且保持无功功率对应的电压幅值不变，从而实现并联系统中光伏单元的最大功率输出。通过PSIM电力电子仿真软件对光伏逆变最大功率约束下垂控制策略进行仿真验证。结果表明，变步长的扰动观察法及改进型下垂控制策略在实际应用中的有效性及可行性。

Research on Droop Control Strategy Based on Photovoltaic Inverter Maximum Power Constraint

Photovoltaic inverter system is based on the traditional droop control method to achieve the average distribution of active power, which will cause the maximum power restriction and waste of photovoltaic units. Therefore, in order to improve the optimal utilization rate of photovoltaic unit output energy, an improved droop control strategy for photovoltaic inverter is proposed. The strategy is based on the variable step perturbation observation method to track and control the maximum power of photovoltaic panels. The maximum output power constraint will generate the droop active power compensation, which will be superimposed to the correction of the frequency reference value corresponding to the traditional droop control active power, and keep the voltage amplitude corresponding to the reactive power unchanged, so as to achieve the maximum power output of photovoltaic units in the parallel system. The maximum power constrained droop control strategy of photovoltaic inverter is simulated and verified by PSIM power electronics simulation software. The simulation results show that the variable step disturbance observation method and the improved droop control strategy are effective and feasible in practical application.