Research Journal of Applied Sciences, Engineering and Technology 3(12): 1396-1401, 2011 ISSN: 2040-7467 © Maxwell Scientific Organization, 2011 Submitted: July 22, 2011 Accepted: September 18, 2011 Published: December 26, 2011 Corresponding Author: Sayed Mojtaba Shirvani Boroujeni, Department of Electrical Engineering, Boroujen Branch, Islamic Azad University, Boroujen, Iran, Tell.: + 983824223812; Fax + 98983824223812 1396 Multi-area Load Frequency Control using IP Controller Tuned by Particle Swarm Optimization Sayed Mojtaba Shirvani Boroujeni, Babak Keyvani Boroujeni, Mostafa Abdollahi and Hamideh Delafkar Department of Electrical Engineering, Boroujen Branch, Islamic Azad University, Boroujen, Iran Abstract: In this study an optimal load frequency controller for multi area electric power systems is presented. In multi area electric power systems if a large load is suddenly connected (or disconnected) to the system, or if a generating unit is suddenly disconnected by the protection equipment, there will be a long-term distortion in the power balance between that delivered by the turbines and that consumed by the loads. This imbalance is initially covered from the kinetic energy of rotating rotors of turbines, generators and motors and, as a result, the frequency in the system will change. Therefore The Load Frequency Control (LFC) problem is one of the most important subjects in the electric power system operation and control. In practical systems, the conventional PI type controllers are carried out for LFC. In order to overcome the drawbacks of the conventional PI controllers, numerous techniques have been proposed in literatures. In this paper a IP type controller is considered for LFC problem. The parameters of the proposed IP controller are tuned using Particle Swarm Optimization (PSO) method. A multi area electric power system with a wide range of parametric uncertainties is given to illustrate proposed method. To show effectiveness of the proposed method, a PI type controller optimized by PSO is incorporated in order to comparison with the proposed IP controller. The simulation results on a multi area electric power system emphasis on the viability and feasibility of the proposed method in LFC problem. Key words: IP controller, load frequency control, particle swarm optimization, multi area electric power system INTRODUCTION For large scale electric power systems with interconnected areas, Load Frequency Control (LFC) is important to keep the system frequency and the inter-area tie power as near to the scheduled values as possible. The input mechanical power to the generators is used to control the frequency of output electrical power and to maintain the power exchange between the areas as scheduled. A well designed and operated power system must cope with changes in the load and with system disturbances, and it should provide acceptable high level of power quality while maintaining both voltage and frequency within tolerable limits. Many control strategies for Load Frequency Control in electric power systems have been proposed by researchers over the past decades. This extensive research is due to fact that LFC constitutes an important function of power system operation where the main objective is to regulate the output power of each generator at prescribed levels while keeping the frequency fluctuations within pre-specifies limits. A unified tuning of PID load frequency controller for power systems via internal mode control has been proposed by Tan (2010). In this paper the tuning method is based on the Two-Degree-of-Freedom (TDF) internal model control (IMC) design method and a PID approximation procedure. A new discrete-time sliding mode controller for load-frequency control in areas control of a power system has been presented by Vrdoljak et al. (2010). In this study full-state feedback is applied for LFC not only in control areas with thermal power plants but also in control areas with hydro power plants, in spite of their non minimum phase behaviors. To enable full-state feedback, a state estimation method based on fast sampling of measured output variables has been applied. The applications of artificial neural network, genetic algorithms and optimal control to LFC have been reported by Kocaarslan and Cam (2005), Rerkpreedapong et al. (2003) and Liu et al. (2003). An adaptive decentralized load frequency control of multi- area power systems has been presented by Zribi et al. (2005). Also the application of robust control methods for load frequency control problem has been presented by Shayeghi et al. (2007) and Taher and Hematti (2008). This study deals with a design method for LFC in a multi area electric power system using a IP type controller whose parameters are tuned using PSO. In order to show effectiveness of the proposed method, this IP controller is