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--- Abstract — This paper attempts to develop a linearized model of automatic generation control (AGC) for an interconn ected reheat type two-area thermal power system under deregulated environment. A comparison between a an conventional integral controller, proportional integral derivative (PI) controller and a fuzzy logic based controller is presented and the proposed fuzzy based controller is shown to generate the best dynamic response following a step load change with different cases of bilateral contracts in deregulated environment. In addition, performance of conventional integral controller, propo rtional integral derivative (PI) controller and a fuzzy logic based controller is also examined under various changes ±30% in system parameters with various bilateral contracts between control areas. Keywords: Two area power system, load frequency control, fuzzy logic controller, deregulated environment. I. I NTRODUCTION In a traditional electric power system, vertically integrated utility (VIU) owned generation, transmission, and distribution, and supplies power to the customers at regulated rates. In the restructured power systems the main concept is transformation from vertically integrated utilities (VIU) to open energy market system. Aim of this was to enhance the economical efficiency of power system. With this market participants who are in this open energy market to provide energy services will be more competitive. The open market system will consist of generation companies (GENCOS), distribution companies (DISCOS), and transmission companies (TRANSCOS) and independent system operator (ISO). Independent System Operator (ISO) is introduced to implement to achieve a secure and economical operation of power systems in restructured power system [2] [4]. In a power system, electricity is continuously produced and consumed simultaneously and power balance of demand-supply ratio must be maintained. In open energy market particular DISCO has the freedom to purchase the power with any GENCO, it may be in intra or inter control area. ISO is independent and disassociated agent for market participants. In the open energy market, all the transactions are done under the supervision of the ISO. There are various ancillary services are controlled by IS0 to provide secure, reliable and economical power transmission. Automatic generation control (AGC) is one of ancillary services of ISO [6]. The DISCO participation matrix (DPM) is helps to visualize the various contracts made between GENCOs and DISCOs. The schematic block diagram of two area system in deregulated environment is shown in Fig. 1. Each area is containing two GENCOs and two DISCOs [1] [6]. Block diagram of closed loop controlled system model with fuzzy controller of reheat type two-area thermal generating system is shown in Fig. 2. When power systems are connected, tie-line flows as well as frequency must be controlled. Maintaining frequency and power interchanges with interconnected control areas at the scheduled values are the two main primary objectives of a power system AGC. The Automatic Generation control for interconnected power system, achieved by measuring deviation in frequency and tie-line power flows, composite variable called the area control error (ACE) [7]. This paper presents the performance of interconnected reheat type two area thermal system Frequency Stabilization using Fuzzy logic based Controller for Multi-Area power system in Deregulated Environment Y.K.Bhateshvar and H.D.Mathur
