Risk-based constraint relaxation with high penetration of wind resources

Abstract

This paper is motivated by infeasibilities in look-ahead economic dispatch with significant wind integration; such infeasibilities result from transmission line constraints that cannot be satisfied within a security constrained economic dispatch. Thus, constraint relaxation is necessary to achieve the dispatch decisions and market solution. The acceptable relaxation margin is determined by assessing the time duration of the thermal overloads in terms of an adaptive transmission rate (ATR). ATR is calculated using the dynamic heat balance equation associated with thermal overloading probability. Furthermore, high wind energy penetration increases variability in circuit flows. We utilize conditional value at risk to evaluate the effects of overloads on system security. We propose a systematic methodology of riskbased constraint relaxation (RBCR) to eliminate the infeasibilities of thermal limits in the stochastic look-ahead SCED problem. Finally, the methodology of RBCR has been verified using an IEEE 6 bus testing system.