The Selection of Online Power Flow Calculation’s Known Quantities

Abstract

The difference between schedule power flow and online power flow is that the former has no corresponding physical power flow, while the latter is the reappearance of existing physical power flow. Owing to the different premise, the selection of power flow calculation’s known quantities can be different. A schedule power flow schedules physical power flow for power system, so the selection of known quantities has strict requirements, such as active power and reactive power regulation capability. Since the physical power flow exists, the selection of online power flow calculation’s known quantities can be more flexible. For example, we can choose load bus as slack bus or replace PQ bus with PV bus. The example demonstrated that we could locate the stealing electricity buses by choosing load bus as slack bus. Considering that voltage amplitude measurement accuracy is higher than reactive power measurement accuracy, we can replace PQ bus with PV bus and make the power flow calculation results more consistent with the physical power flow. Finally, the examples show that online power flow calculation’s known quantities can be selected flexibly according to the actual situation rather than strictly following the classical power flow calculation requirements.