Risk-based security-constrained economic dispatch in power systems

Based on a new perspective in coordinating with the traditional"N-1"criteria and system risk,a real-time electricity market model is presented,in which the system risk is employed to model the system’s overall security level.This new model is called the risk-based security-constrained economic dispatch(RB-SCED).Relative to the securityconstrained economic dispatch(SCED)used in the power industry today,the RB-SCED finds more secure and economic operating conditions.It does this by obtaining solutions that achieve a better balance between post-contingency flows on individual branches and the overall system risk.The method exploits the fact that,in a SCED solution,some postcontingency branch flows which exceed their limits impose little risk while other post-contingency branch flows which are within their limits impose significant risk.The RB-SCED softens constraints for the former and hardens constraints for the latter,thus achieving simultaneous improvement in both security and economy.In this work,the basic concept and the mathematical formulation of the RB-SCED model are systematically described.Experimental results on a 9-bus system and the ISO New England actual system have demonstrated the advantages of RB-SCED over SCED.

Dynamic-decision-based Real-time Dispatch for Reducing Constraint Violations

This paper proposes a dynamic-decision-based realtime dispatch method to coordinate the economic objective with multiple types of security dispatch objectives while reducing constraint violations in the process of adjusting the system operation point to the optimum.In each decision moment,the following tasks are executed in turn:①locally linearizing the system model at the current operation point with the online model identification by using measurements;②narrowing down the gaps between unsatisfied security requirements and their security thresholds in order of priority;③minimizing the generation cost;④minimizing the security indicators within their security thresholds.Compared with the existing real-time dispatch strategies,the proposed method can adjust the deviations caused by unpredictable power flow fluctuations,avoid dispatch bias caused by model parameter errors,and reduce the constraint violations in the dispatch decision process.The effectiveness of the proposed method is verified with the IEEE 39-bus system.