RETRACTED ARTICLE: Estimation of loadability limit with N-1 and N-2 outages using evolutionary computation techniques

Abstract

Voltage stability primarily depends on the voltage magnitude, phase angle, real and reactive power constraint of the electric power system. Even during emergencies like contingency (outages), the stability of the electric power structure will be enhanced by improving the Loadability Limit (LL) of the transmission sector. Flexibility in the real and reactive power flow in the transmission system is achieved by the Flexible AC Transmission System (FACTS) devices. These devices can be placed anywhere in the transmission sector. To get effective control over the power flow through the transmission lines and to achieve the maximum loadability with the minimal installation cost, optimal choice and placement of FACTS devices are essential. In this manuscript, efforts had been taken to analyze the LL with outages for hybrid electric power structures. The proposed method is simulated and tested with the hybrid version of standard IEEE 30 bus system. Three types of FACTS devices like Thyristor Controlled Series Capacitor (TCSC), Static VAr Compensator (SVC) and Unified Power Flow Controller (UPFC) are efficiently selected and placed in the transmission lines. For the optimal positioning and placement of these devices, the Contingency Severity Index (CSI) and Fast Voltage Stability Index (FVSI) have been used. Differential Evolution (DE) and Modified Differential Evolution (MDE) algorithms are applied to optimize the obtained results. DE is an evolutionary search based soft computing algorithm popularly handed to resolve multifarious problems. MDE is the enhanced version of DE that embraces a prior knowledge about the solution space at every stage of the search. The main focus of this work is (i) to identify the weak branches and buses in the system using CSI and FVSI. (ii) to optimize the number, location and settings of FACTS devices using various soft computing techniques like DE and MDE. (iii) to evaluate ML of a transmission system with FACTS devices under normal and contingency conditions using DE and MDE. (iv) to calculate the cost required for the installation of FACTS devices. (v) to enhance ML of pool and hybrid model of deregulated electric power market with contingency using the optimal number, rating and positioning of FACTS devices.