RESEARCH ARTICLE Fruit fly algorithm‐based automatic generation control of multiarea interconnected power system with FACTS and AC/DC links in deregulated power environment Ravi Shankar 1 | Ashiwani Kumar 1 | Utkarsh Raj 1 | Kalyan Chatterjee 2 1 Department of Electrical Engineering, NIT, Patna, India 2 Department of Electrical Engineering, IIT (ISM), Dhanbad, India Correspondence Kalyan Chatterjee, Department of Electrical Engineering, IIT (ISM), Dhanbad, India. Email: kalyanchatterjee@iitism.ac.in Summary This paper focuses on automatic generation control (AGC) in deregulated envi- ronment for the multiarea interconnected power system. Each area consists of different kind of generating sources like thermal, hydro, and gas, each having different characteristics with physical constraint likes governor dead band and generation rate constraint. Loads are divided among different generator using the concept of economic load dispatch. The AC/DC links has been installed in all areas as well as unified power flow controller (UPFC) in tie lines to mitigate the effect of oscillation and to improve the system response. Thus, a more systematic and synchronized control of AGC with UPFC and AC/DC links has been proposed. Small signal stability of each area has been analyzed for finding out the oscillation states of the studied system. The proposed controller is optimized through Fruit Fly Algorithm, and its promising results reveal that the proposed controller is more efficient and effective in all different power transaction modes of restructured scenario. KEYWORDS AC/DC links, automatic generation control (AGC), deregulated environment, fruit fly optimization algorithm (FOA), PID controller, unified power flow controller (UPFC) List of symbols and abbreviations: U, control input vector; X, state vector; Y, output vector; λ, eigen value; Δf 1 , deviation in frequency of area‐1; Δf 2 , deviation in frequency of area‐2; Δ Ptie , deviation in tie‐line power; ΔP upfc , deviation in power output due to UPFC; ΔP ti1 , deviation in thermal turbine output; ΔP mi1 , deviation in intermediate state of reheat turbine; ΔP gi1 , deviation in steam turbine governor output; ΔP mi2 , deviation in hydro turbine output; ΔP ti2 , deviation in output of mechanical hydraulic governor of hydro turbine; ΔP gi2 , deviation in intermediate state of hydro turbine governor; ΔP mi3 , deviation in gas turbine output; ΔP ti3 , deviation in fuel system output of gas plant; ΔP gi3 , deviation in valve position of gas plant; ΔP g′i3 , deviation in governor system of gas plant; ΔP dci , deviation in power output due to dc link; K dc , gain constant of DC link; T dc , time constant of DC link; P real , real power injection; Q reactive , reactive power injection; V r , receiving end voltage; V s , sending end voltage; V se , series voltage magnitude; φ se , series voltage phase angle; ΔP di , total change of load; ΔP loc , sum of all the local contracted demand; ΔP UL , sum of all the local contracted demand; ΔP di , deviation of load in area‐i; R thi , speed regulation of thermal plant; R hyi , speed regulation of hydro plant; R gi , speed regulation of gas plant; B i , damping coefficient; Pf i1 , participation factor of generator‐1of i th area; Pf i2 , participation factor of generator‐2 of i th area; Pf i3 , participation factor of generator‐3 of i th area; ACE, area control error; apf, ACE participation factor; cpf, contract participation factor; ISE, integral square error; X, transmission line reactance Received: 25 August 2017 Revised: 10 June 2018 Accepted: 11 July 2018 DOI: 10.1002/etep.2690 Int Trans Electr Energ Syst. 2018;e2690. https://doi.org/10.1002/etep.2690 © 2018 John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/etep 1 of 25