INTERNATIONAL JOURNAL of RENEWABLE ENERGY RESEARCH S. S. Pati and S. K. Mishra, Vol.9, No.2, June, 2019 A PSO Based Modified Multistage Controller for Automatic Generation Control with integrating Renewable Sources and FACT Device Subhranshu Sekhar Pati*‡, Saroj Kumar Mishra* *Department of Electrical Engineering, International Institute of Information Technology Bhubaneswar, Odisha, India, 751003 (subhranshupati16@gmail.com, saroj@iiit-bh.ac.in) ‡ Subhranshu Sekhar Pati; Department of Electrical Engineering, IIIT Bhubaneswar, Odisha, India, 751003 Tel: +91 966 851 8951, subhranshupati16@gmail.com Received: 27.02.2019 Accepted:01.04.2019 Abstract- This study focuses on modelling of two area hydro-thermal interconnected system integrated with wind, Small Hydro Plant (SHP) and Solar Thermal Plant (STP). Flexible AC Transmission (FACT) device named as Static Synchronous Series Compensator (SSSC) and an energy storing element called Super Magnetic Energy Storage (SMES) unit is incorporated in the model. To control and monitor the test system, an effective Particle Swarm Optimization (PSO) optimized multistage controller is proposed. The proposed controller parameters are optimized through PSO technique. The effectiveness of the suggested controller is verified under diverse step and time varying load perturbation. The superiority of controlling action of the proposed controller is also proved to be efficient than other prominent controllers. System stability is analysed and found to be stable through the establishment of Eigen value analysis and bode plot. Furthermore, the system behaviour is studied with various combinations of SSSC and SMES in different area simultaneously. To make the analysis more realistic, appropriate time delay is included in the proposed study. Finally, sensitivity analysis of the network by varying the different system parameters, governed through a multistage controller is carried out. Keywords Automatic Generation Control; Particle Swarm Optimization; Solar Thermal Plant; Static Synchronous Series Compensator; Super Magnetic Energy Storage. 1. Introduction A reliable power network is characterized by its associated system constraints and depends upon successful control strategies for economical operation. With regard to that, AGC is one of the effective strategies which need to be reflected in the power structure for deriving output. The prime objective for including AGC in the power system is to maintain the frequency deviation within the prescribed limit and regulate the incremental power change in tie line called as tie line power at scheduled level. Normally in the present scenario, electrical energy is harvested form conventional power plant such as thermal and hydro. Also literatures survey [1-3] revels that, most of the works performed in the field of AGC study for an interrelated power system is focusing on various combinations of thermal and hydro units. Moreover, the transfer function of hydro turbine is not same as of thermal as it holds non-minimum phase characteristics and make the design of hydro plant different to thermal. Apart from these, integration of renewable power plant like wind, CSP and SHPP with the grid, make the whole system more reliable. Normally, renewable power plants are used as peak load power plant [4]. Therefore, the effect of renewable power plant on the system behavior with concerning to AGC need to further explored. After pioneering work done by Elgerd et al. [1] in the field of AGC, Nanda et al. extends the AGC work to two area hydro-thermal system by considering the nonlinearity i.e. GRC [2]. The same author also carried out the study with three area system using GRC and reheat turbine. Later Saika et al. have performed analysis on two area system as well as three and five area unequal system incorporating various non-linarites [3]. Due to carbon emission from fossil fuel burning plants and its hazardous impact on environment, it is urgency to adopt renewable based power plants. SHP is a clean, economical and low investment renewable based power plant and gaining popularity day by day. Dolla et al. used this high efficient plant in the area of load dumping by regulating water pressure in connecting tubes [4]. The mathematical representation of SHP in terms of transfer function is presented by Fan et al. [5]. The author in [5], also analyzed the frequency deviations and tie line power with considering