孤岛运行交直流混合微电网的潮流计算

Power Flow Calculation of Islanded Hybrid AC/DC Microgrid

交直流混合微电网包含交流子系统、直流子系统及连接2种子系统的互连变换器(interlinking converter,ILC)。针对下垂协调控制策略下孤岛运行交直流混合微电网的潮流计算,提出基于带新型线性搜索三步LM(three-steps Levenberg Marquardt algorithm with a new line search,NTLM)算法的交替迭代方法。首先分析ILC装置的控制方法,建立其节点潮流模型;结合提出的3种直流节点类型和4种交流节点类型,建立交、直流子系统的统一潮流模型。然后提出NTLM算法求解统一潮流模型,在此基础上,进行交、直流子系统交替迭代潮流计算,得到交直流混合微电网的潮流解。最后,通过改造的孤岛运行交直流混合微电网系统的仿真算例,验证所提方法的正确性和有效性。

Hybrid AC/DC microgrid includes AC subgrid, DC subgrid and interlinking converter（ILC） connecting AC and DC subgrids. To calculate power flow of islanded hybrid AC/DC microgrid using droop-coordination control strategy, an alternative iteration method based on three-step Levenberg-Marquardt algorithm with new line search（NTLM） is proposed in this paper. Control method of ILC unit is analyzed and nodal power flow model is established. Three types of DC nodes and four types of AC nodes are proposed, and a unified power flow model for AC and DC subgrids is set up. Then NTLM algorithm is proposed to solve the unified power flow model. On this basis, power flows of AC and DC subgrids are calculated, iterating alternatively to obtain power flow solution of the hybrid AC/DC microgrid. Finally, the proposed method is tested in an islanded hybrid AC/DC microgrid system, and test results verify feasibility and effectiveness of the proposed method.