Reactive Power Reallocation for Loss Minimization, Voltage Profile Improvement, and Voltage Stability Enhancement Using Moth Flame Algorithm

Abstract

The Power industry became the most vital part of the economic development of the nation. In modern century power system is the back bone of economic development and prosperity of the nation. The demand of electricity and the area of its utilization has been increasing day by day. Major portion of the electricity demand is still served by the conventional type of the fuel which is on the verge of depletion. Optimal use of energy has always been the matter of interest. Since, the power system has been back bone of the prosperity and economic development, the availability, security of the power system has been the factor to be augmented. So, economics and the security of the electricity system has been the center of concern. Optimal use of energy and the enhancing the stability of the system is the important features of power system operation. The major power system crisis occur in the system is because of the scarcity of the energy sources and the failure of the system due to instability. Most of the black out of the system is caused by Voltage instability. In this thesis work, we have concerned about the economics of operation and the enhancement of the system Voltage stability and Voltage quality. The economics of the operation is concern with the reduction of the loss. The reduction of the loss and the Voltage profile improvement as well as Voltage stability enhancement is achieved by the reallocation of the reactive power dispatch for generation and the shunt compensation. The reallocation of reactive power causes to rearrangement of the reactive power flow pattern in the line and the loss, and Voltage profile and stability will be altered. The dispatch of the reactive power at which the loss is minimized, Voltage profile is improved and Voltage stability is enhanced is optimal dispatch. The Optimal reactive power dispatch solution is obtained through the moth flame optimization technique, which is newly developed and very effective in implementation. This algorithm is inspired by the nature moth movement with respect to light. The implementation of this optimization problem is done with the IEEE 57 standard bus. In the standard bus, the Optimal dispatch of 7 generator and 3 compensators is obtained. 5 The dispatch of reactive power of generator and shunt compensation is controlled by the AVR of Generator, the tap setting of transformers and the switching of static compensation. So, taking these as the control variable for the optimization problem, the optimized control value is obtained by the moth-flame algorithm, then later the respective dispatch of reactive power generation is calculated. The Voltage stability is measured by the L- index indices. It reflects the margin of the actual state from the point of Voltage collapse. Due to inbound nature of the L-index for 0-1, it became practical for optimization problem. In our thesis work, the loss minimization, Voltage deviation minimization and Stability enhancement is three independent objectives. The control variable for the IEEE 57 bus, system consists of 7 generator Voltage, 15 transformers tap setting and 3 compensators. The optimal value of control variable is obtained after the optimization is done. The Optimal dispatch of reactive power is calculated through the load flow after the optimal value of control variable is obtained. Initially, At Base condition, the active power loss was 27.86 MWatt, Voltage Deviation index (VDI) = 3.814074, and L-index (max) was 0.3099. When the MFO is applied for the objective of Minimum Loss condition, the loss is reduced to minimum value of 24.09 MWatt, VDI is also changed to 2.7026, and L-index max is deducted to 0.3099. The Optimization is done for voltage profile improvement, the Voltage deviation index (VDI) is obtained at its minimum value of 1.469248, in this case, loss is also deducted to 26.99 MWatt, and stability is also enhanced to 0.2727 MWatt. When MFO is applied for voltage stability Enhancement, the L-index (max) value is reduced to 0.2653, and loss at that condition is 27.49 MWatt, Voltage Deviation index (VDI) = 2.897311. In all three cases, the Objective is minimized in respective aspects, and the operating scenario is better in all three aspect of loss, voltage profile and voltage stability than that at the base condition. After conduction of moth flame methodology to the optimization problem for each independent objective, it is reflected that rearranging the reactive power flow in the line could reduce the impact of reactive power flow. After optimization the loss is reduced in significant value, and the Voltage profile and much improved and stability is enhanced. The moth flame shows very effectiveness on solving the non-linear optimization problem for the optimal reactive power dispatch.