Optimal Reactive Power Dispatch for Voltage Instability Alleviation Using Evolutionary Programming Technique

Abstract:- In the current power system planning and operation, a lot of concern has been shown in the security of the system and stability analysis. The load sharing or generation scheduling patterns have resulted in heavy flows which lead to greater losses; intimidate stability, security and eventually making certain generation patterns undesirable. With increased loading of existing power transmission systems, the voltage instability problem and voltage collapse have also become a major anxiety in power system planning and operation. Although voltage stability is more dependent on the reactive power sources or voltage profile in the system, it is also a function of real power flows. Voltage instability can be alleviated by performing reactive power dispatch in power transmission system. Reactive power dispatch problem embraced the voltage instability alleviation and minimisation of real power transmission losses while satisfying the equality and inequality constraints. This paper presents the optimal reactive power dispatch as a reactive power planning approach for alleviating voltage instability problem based on Evolutionary Programming (EP) optimisation technique. A line-based voltage stability index was chosen as the basis of the optimisation process, while voltage instability alleviation was chosen as the objective function. Extensive testing of EP was conducted and results are included to demonstrate the effectiveness of the proposed technique. From the study, it was revealed that the proposed EP optimisation technique has successfully alleviated the voltage instability condition and reduced the total loss, while improving the voltage in the system within minimal iteration number