Uniform iterative power flow algorithm for systems equipped with VSC-HVDCs

VSC-HVDCs, based on voltage source converters(VSC), are the new generation of high voltage direct current(HVDC) transmission technology. This technology has attracted more and more attention for its favorable benefits such as no risk of commutation failures and possibility to feed to a weak ac system or even passive loads. The operation principle of VSC-HVDC and control modes of VSC were analyzed firstly. Considering different control modes of VSC,correction equations were deduced for VSC's ac buses and VSC-HVDCs respectively. On the basis of these correction equations, a uniform iterative power flow calculation algorithm for systems equipped with VSC-HVDCs was proposed. The validity of this algorithm was verified by power flow calculation for the modified WSCC-9-nodes ac and dc hybrid system. At the end, the steady-state characteristic and power loss characteristic of VSC-HVDCs were analyzed by use of this algorithm.