CSEIT1952271 | Received : 15 March 2019 | Accepted : 07 April 2019 | March-April -2019 [ 5 (2) : 1019-1025 ] International Journal of Scientific Research in Computer Science, Engineering and Information Technology © 2019 IJSRCSEIT | Volume 5 | Issue 2 | ISSN : 2456-3307 DOI : https://doi.org/10.32628/CSEIT1952271 1019 A Comparative Study on Load-Frequency Controllers of a Five- Area Interconnected Power System Dao Thi Mai Phuong Department of Electrical Engineering Technology, Hanoi University of Industry, Hanoi, Vietnam ABSTRACT The crucial objectives of load-frequency control (LFC) to a multi-area interconnected power system are to maintain the system frequency at a nominal value (50 Hz or 60 Hz) and the tie-line power flows at predetermined values. Based on tie-line bias control strategy, conventional regulators, such as I, PI and PID, were initially used for solving the LFC problem. Due to the complexity, nonlinearity and uncertainty of a multi-area power system in practice, the conventional regulators may not obtain the control performances good enough to bring the network back to the steady state as soon as possible. Meanwhile, intelligent controllers, such as fuzzy logic (FL)-based controllers, are able to completely replace these conventional counterparts. The superiority of the FL-based LFC controllers over the conventional ones for a typical case study of five-area interconnected power grids is validated in this paper through numerical simulations implemented in Matlab/Simulink package. It should be apparent from this comparative study that the LFC controller based on FL technique is a feasible selection in dealing with the LFC problem of a multi-area power network. Keywords: LFC, Five-Area Interconnected Power System, Conventional Regulator, Intelligent Controller, FL I. INTRODUCTION Together with voltage, frequency is a highly important parameter in power system operation and control. The frequency of an electric power grid is a systematic parameter, which is required to be a constant value at any point of the network. The nominal value of the electric power network frequency is 50Hz for most countries in the world, except in the US and Western of Japan the network frequency is 60Hz. It is an undeniable fact that the network frequency changes over time depending on load characteristic which is always varying in an electric power grid. Unacceptable system frequency deviations from the nominal value affect a lot of devices, causing unstable and uneconomic operation of an electric power grid [1-3]. Therefore, it is necessary to establish robust load frequency control (LFC) strategies to control the automatic generation in an interconnected power system [1]. In general, the main roles of these control strategies are to maintain the frequency and tie-line power to ensure the optimal and economical generation in the power network. Based on the tie-line bias control principle, two types of LFC controllers have been applied, namely conventional and intelligent controllers. At first, the conventional controllers based on the integral (I), proportional-integral (PI), or proportional-integral- derivative (PID) regulators are used successfully to reduce the frequency and tie-line power deviations. However, by applying these controllers, main control