Transmission Contingency Selection Considering Impact of Uncertain Distributed Generation

Traditionally, to ensure the power system security a list of critical contingencies is shortlisted for detailed analysis. The system operator of transmission system (TS) considers the distribution system (DS) as a fixed aggregated load at the point of connection bus. The load value indicates the power demand of DS from the grid. However, this demand is no longer fixed if the uncertainties associated with renewable distributed generation (DG) units is taken into consideration. Thus, any component outage which is not severe may become critical when there is an increase in power demand by DS due to unexpected change in weather conditions. Hence, to prevent missing out a potential alarm signal during such events, the critical contingency selection (CS) has to be made considering the impact of uncertain distributed generation in DS. This paper proposes the methodology for transmission contingency selection based on decoupled-coordinated AC load flow between different system operators. Numerical simulations are performed on a test system to show the changes in contingency ranking due to uncertain renewable DG units.