微电网运行模式无缝切换控制策略

Seamless switching control strategy of micro grid operation mode

微电网作为分布式电源的载体,可以在合理分配分布式电源所产生电能的同时避免其直接与主电网连接所带来的弊端。微电网运行模式间的无缝切换过程直接影响到微电网的安全稳定性与供电可靠性。针对微电网由孤岛转为并网时的切换过程,基于基尔霍夫定律进行推导得到逆变器相关变量间的数学关系,构建三相负荷不对称条件下微电网逆变器由独立运行转为并列运行的动态优化数学模型。利用基于Radau配置的动态优化算法对该模型进行离散化,并将优化时间段分成若干区间,在区间上通过正交配置法确定配置点,继而获得每个配置点上的优化结果。通过MATLAB进行仿真求解,得到了控制变量的最优控制轨迹。

As the carrier of the distributed generation,micro grid can avoid the disadvantages of the direct connection with the main power grid while the power generated by the distributed generation is reasonably allocted. The seamless switching process between micro grid operation modes directly affects its security,stability and reliability. According to the process of micro grid from the island mode to the grid connected mode,the mathematical relationship between the variables of the inverters is obtained based on Kirchhoff＇s law,and the mathematical model of the micro grid inverters with unbalanced three-phase load from island mode to grid connected mode is constructed. The model is a dynamic optimization one,and the dynamic optimization algorithm based on Radau configuration method is used to discretize it,and the optimization time is divided into several intervals. The collocation points at each interval are determined by the orthogonal collocation method,and then the optimization results at each configuration point are obtained. The optimal control trajectories of the control variables are obtained by MATLAB.