Optimal Allocation of Static Synchronous Series Compensator Controllers using Chemical Reaction Optimization for Reactive Power Dispatch

Introduction

In recent years, the ongoing restructuring of power sector and growing electricity demand, has led power system networks to operate the transmission network closer to the thermal operating limit. However, due to the increasing load demand, more and more power is required to be pushed over the existing transmission lines but increase in the power flow above a certain operating level increases power loss, reduces the voltage profile and decreases the overall stability of the system. In recent years, there are emerging technologies available which can help to deal with problems of power system. To achieve better power flow control over the existing transmission lines without violating the stability margin of the system, application of flexible ac transmission system (FACTS) “Mamandur and Chnoweth (1981); Roy, Ghoshal and Thakur(2011) ”may be adopted. In the view of the above, the main objective of this research work is to propose new, efficient optimization techniques to locate various FACTS devices in optimal position in order to minimize transmission loss and voltage stability of short, medium and large scale power systems. There are a number of FACTS devices available, such as, the Static Synchronous Series compensator (SSSC) “Basu, M. (2008); Vijayakumar and Kumudinidevi (2008)” which can be used to generate and insert a series voltage, and it can be regulated to change the impedance of the transmission line. In this way, the power flow of transmission line is controlled.

Optimal reactive power dispatch (ORPD), a sub problem of optimal power flow (OPF), has significant influence on the economic and secure operation of power systems. The problem of ORPD is to allocate reactive power generation so as to minimize the real power transmission losses or the voltage deviation, while a number of equality and inequality constraints, including the power flow equations, upper and lower voltage limits of the generators, and capacity restrictions in various reactive power sources such as generators, shunt capacitor banks, and transformer taps, are satisfied. ORPD is a complex combinatorial optimization problem involving a nonlinear objective function nonlinear constraints, and both continuous and discrete variables.