Design of an Optimized Fractional High Order Differential Feedback Controller for Load Frequency Control of a Multi-Area Multi-Source Power System With Nonlinearity

Erdinc Sahin

doi:10.1109/access.2020.2966261

Abstract

Load frequency control (LFC) is one of the essential process in interconnected power systems. To provide high quality, reliable and stable electrical power, designed controller should perform satisfactorily, i.e. suppress area frequency and tie-line power deviations. Within this scope, in this study, a high order differential feedback controller (HODFC) and a developed fractional high order differential feedback controller (FHODFC) are proposed for LFC problem in multi-area power systems for the first time. The gains of the HODFC and FHODFC are optimally tuned by particle swarm optimization (PSO) algorithm aiming to minimize integral of time weighted absolute error (ITAE) performance index. The superiority of the developed FHODFC are verified by comparing reported controller structures in the recent state-of-the-art literature and HODFC for two identical non-reheat thermal power system and two-area multi-source power system consisting of gas, thermal and hydro generation units with/without consideration of HVDC link. To test the robustness of the designed controllers, varying system parameters and loading conditions are investigated. The governor dead band (GDB) and generation rate constraint (GRC) limitations are also considered for the system under study to examine non-linearity handling success of the proposed controllers. Performance results indicate that the developed FHODFC provides better dynamic response and robustness than other published techniques under nonlinearities, random load pattern, and variations in system parameters and loading conditions.

Highlights

To operate a reliable and stable electrical power system, a system frequency should be kept at scheduled value or its deviation should be regulated as soon as possible in case of variation in load supply or demand [1]
SIMULATION RESULTS AND DISCUSSION In order to show the effectiveness of the proposed high order differential feedback controller (HODFC) and fractional high order differential feedback controller (FHODFC), different type power systems are considered for Load frequency control (LFC) problem
particle swarm optimization (PSO) algorithm is employed to find the minimum value of integral of time weighted absolute error (ITAE) which is commonly preferred in reported studies in literature for LFC problem

Summary

INTRODUCTION

To operate a reliable and stable electrical power system, a system frequency should be kept at scheduled value or its deviation should be regulated as soon as possible in case of variation in load supply or demand [1]. The LFC or automatic generation control (AGC) keeps the system frequency and the tie line power flow at their scheduled values under normal and disturbed conditions. Dynamic responses of area frequency and tie-line power of LFC system with classical I/PI/PID controllers have large oscillations and longer settling time under consideration of physical limitations, system uncertainties, and change in loading conditions [27]. Researchers have attempted to set controller parameters optimally by using meta-heuristic algorithms, classical and artificial intelligence methods. To compare performance of the proposed FHODFC with other published controller techniques considering OF value and transient response characteristics.

MATHEMATICAL MODEL OF THE STUDIED POWER SYSTEM

FRACTIONAL HIGH ORDER DIFFERANTIAL FEEDBACK CONTROLLER

PARTICLE SWARM OPTIMIZATION

SIMULATION RESULTS AND DISCUSSION

FIRST TEST SYSTEM WITH GOVERNOR DEAD BAND

CONCLUSION