交直流型微电网中光伏逆变器并联控制策略

针对光伏电源和储能装置主要配置在直流网,交流网在离网时需克服光伏电源出力波动的问题,提出一种微电网离网模式下的光伏逆变器并联控制策略:直流网侧逆变器为主逆变器,采用恒定电压幅值以及 P-f 下垂法为交流网提供全部无功及部分有功功率;少数较小容量的光伏逆变器为从逆变器,从逆变器不提供无功,采用自适应下垂系数法输出与实时最大功率匹配的有功功率,既维持交流网电压稳定,又充分利用光伏发电.基于 MATLAB 的系统模型仿真证明了该方法的正确性与可行性.

An Adaptive Control Strategy for Parallel Inverters of Hybrid DC/AC PV Micro-Grid

Photo voltaic(PV) generation and energy storage devices are mainly configured in sub DC network of hybrid AC/DC microgrid and provide power supply for DC load,and using parallel PV inverters a part of PV generations can be connected with sub AC network via point of common coupling(PCC) to supply power for AC loads,thus when sub AC network is being disconnected from conventional power grid the fluctuation of power output of PV generation in sub AC network should be eliminated.A control strategy for parallel PV inverters under the condition of disconnecting sub AC network from conventional grid was proposed:the parallel PV inverter configured in DC network was regarded as master inverter and supply total reactive power and part of active power for sub AC network by constant voltage amplitude and power-frequency droop method;a part of PV inverters with lower capacities were regarded as slave inverters,which did not supply reactive power and supplied only active power controlled by adaptive droop coefficient method,and this part of active power was matched with maximum real-time power of PV generation,thus not only the voltage stability of sub AC network could be maintained,but also the capabilities of PV generations could be fully utilized.Both correctness and feasibility of the proposed control strategy were verified by results of simulation based on Matlab.