Optimum load shedding based on sensitivity to enhance static voltage stability using DE

This paper proposes a methodology to optimize the load curtailments necessary to restore the equilibrium of operating point by accounting for operating and stability inequality constraints. To get desired stability margin Schur's inequality based proximity indicator has been selected whose threshold value along with minimization of load shedding assures desired static voltage stability margin. The methodology anticipates the risk of voltage instability in a time frame using sensitivity of proximity indicator of load flow Jacobian with respect to load. If the normal controls are exhausted, the proposed algorithm based on sensitivity, sheds, required amount of low priority loads in advance. This makes the system to survive voltage instability threat even during worst system period. The buses which are having large sensitivity are selected for load shedding. A computational algorithm for minimum load shedding at selected load buses has been developed using Differential Evolution (DE), Self-adaptive Differential Evolution (SaDE) and Ensemble of Mutation and Crossover Strategies and Parameters in Differential Evolution (EPSDE). Developed algorithm accounts inequality constraints not only in present operating conditions (after load shedding) but also for predicted next interval load (with load shedding). Proposed methodology has been implemented on IEEE 14-bus and 25-bus test systems. Performance of the methodology has been compared with Davidon–Fletcher–Powell's (DFP), Particle Swarm Optimization (PSO), Co-ordinated Aggregation based Particle Swarm Optimization (CAPSO) and Genetic Algorithm (GA) techniques based on statistical inference. Simulation results have been obtained which confirm that the proposed methodology provide considerable mitigation in the load shedding and enhancement in voltage stability. By using this methodology various power system blackouts can be prevented.

► A new search algorithm is proposed for anticipatory load shedding under emergency.
► The proposed algorithm is based on sensitivity and voltage stability considerations.
► A computational algorithm for minimum load shed is developed using DE and its improved variants.
► Inequality constraints are accounted not only in present operating condition but also for predicted next interval.
► The proposed algorithm has been implemented on IEEE 14-bus and 25-bus systems with promising results.