AC-DC load flow with unit-connected generator-converter infeeds

The conventional AC-DC steady state formulation is modified to analyze HVDC load flows with unit-connected generator-converter infeeds. It is found that the steady state algorithm is restricted in its application to large power conditions due to the large commutation overlap caused by the extra reactance of the unit connection. Also, the results are shown to be in considerable error when the generators contain rotor saliency (probably the most common case for a remote generating plant). A concept called the equivalent inverter which uses unit-connection characteristics derived from time domain simulation is presented as a practical alternative for general load flow studies involving unit-connected schemes