VOLTAGE STABILITY INDICATOR FOR IDENTIFICATION OF THE WEAKEST BUS AREA IN POWER-SYSTEMS

Application of Newton optimal power flow (OPF) to identify the weakest bus/area, which is most likely to cause voltage collapse, is presente d in this paper. The S-V curve (complex power to voltage) is examined via Newton OPF. Marginal costs (Lagrange multipliers) regarding power flow equations, VAr generations, voltages and taps, etc., to the syste m MW losses are obtained from Newton OPF. The weakest bus/area in the system is identified by an indicator achieved with these marginal cost s via the Kuhn-Tucker theorem. This indicator helps users know which b us/area is most likely to cause voltage collapse. The IEEE 30-bus and a practical 251-bus systems are used to show the capability and feasib ility of the proposed approach.