Sequential Power Flow Calculation for AC/DC Hybrid Systems with Multi-terminal LCC-HVDC

Line Commutated Converter based-high voltage direct current (LCC-HVDC) systems are an important support for large-scale renewable energy transmission. Compared with two-terminal LCC-HVDC, multi-terminal LCC-HVDC systems are flexible in control and reliable in power supply. However, the integration of multi-terminal LCC-HVDC brings great complexity to the operation modes and power flow of power systems. Therefore, it is very important to resolve the power flow calculation problems of AC/DC hybrid systems containing multi-terminal LCC-HVDC. This paper proposed a sequential power flow calculation algorithm for multi-terminal LCC-HVDC. Firstly, a steady-state model of multi-terminal LCC-HVDC was proposed considering control modes. Secondly, based on the steady-state model, a power flow calculation algorithm for AC/DC hybrid power systems containing multi-terminal LCC-HVDC is designed with sequential iteration methods. Finally, two cases with two-terminal and three terminal LCC-HVDC are tested to verify the accuracy of the proposed model and algorithm.