Probabilistic Analysis of Loadability in Composite Power Systems Considering Security Constraints

Loadability represents the maximum load that can be supplied in a general multi-machine power network. Loadability is limited not only by the violation of system thermal and voltage limits, but also restricted by transient stability limits. Due to the uncertainty of power system behavior, it is impossible to provide a fixed loadability in all conditions. Specifically, in system planning, prospective risk analysis needs a statistical forecast for an expected range of loadability. It is, therefore, important to study loadability problem from a probabilistic point of view. In this paper, an algorithm to incorporate security constraints in calculating loadability is proposed. Monte Carlo simulation is used to accomplish the probabilistic calculation of loadability with consideration of stochastic features of transient stability. The WSCC-9 bus system is used as the test system to demonstrate the methodology