Three-phase power flow calculations by direct ZLOOP method for microgrids with electric vehicle charging demands

A three-phase power flow solution approach for microgrids with electric vehicle (EV) demands is proposed in this study. Based on the loop frame of reference, a direct iterative approach is adopted. Most of microgrids are essentially unbalanced; hence, the proposed approach is developed based on true phase (a-b-c) frame, rather than the sequence-component frame. Based on the true phase frame, the total dimension of the performance equations of the network is the minimum required to represent the microgrid system. The mathematical component models, such as feeders, capacitors/reactors, transformers, automatic voltage regulators, loads, distributed energy resource units and EV demands can easily be involved in the proposed approach. To examine the validity of the proposed algorithm, four IEEE sample systems and a practical Taiwan Power Company distribution system are used as benchmarks for comparisons. The test results show that the proposed approach is accurate, efficient and robust with minimum memory requirements for three-phase power flow studies.