A Method of Expression of Slack-Bus in the Unbalanced Power Flow Calculation

This paper presents a new method to express the slack-bus in the unbalanced power flow calculation based on the phase coordinate method. Although the slack-bus is expressed, in general, as a three phase symmetrical voltage source in unbalanced power flow calculations, this expression results an incorrect solution when a generator with finite rating is connected to the slack-bus. This paper proposes a new method in which the slack-bus is expressed as a quasi P-V specified node.