Design and Control of Grid-Connected PWM Rectifiers by Optimizing Fractional Order PI Controller Using Water Cycle Algorithm

Sushma Kakkar,Baseem Khan,Pratima Walde,Tanmoy Maity,Sanjeevikumar Padmanaban,Rajesh Kumar Ahuja,R K Saket

doi:10.1109/access.2021.3110431

Abstract

In this paper water cycle algorithm-based fractional order PI controller (FOPI) is proposed for virtual flux-oriented control of a three-phase grid-connected PWM rectifier. FOPI controller makes the PWM rectifier control more robust due to the fractional behavior. Fractional-order controllers have an additional degree of freedom, so a wider range of parameters is available to provide better control and robustness in the plant. The optimization and design of the FOPI controller are done using the water cycle algorithm (WCA). WCA is an optimization method inspired by monitoring the water cycle operation and flow of water bodies like streams and rivers toward the sea. The performance of the FOPI controller is compared with the classical integer order PI controller. The parameters of PI and FOPI controllers are optimized and designed using the WCA technique, leading to WCA-PI and WCA-FOPI controllers. The system is tested using MATLAB/Simulink. The simulation results verify the better performance of WCA-FOPI in terms of settling time, rise time, peak overshoot, and Total Harmonic Distortion (THD) of grid current. A robustness measurement with line filter parametric variations and non-ideal supply voltage (unbalance and distorted supply voltage) is carried out. The WCA-FOPI demonstrates more robustness as compared to WCA-PI. Simulation findings validate the WCA-FOPI controller outcomes as compared to WCA-PI in terms of control effect and robustness.

Highlights

The power electronics converters are being used at all levels in power systems using renewable energy sources
The major benefit of fractional order PID (FOPID) controller is to increase in performance of non linear and dynamic systems; and have less sensitivity to changes in parameters of the system
Design and Control of Grid Connected PWM Rectifiers by Optimizing Fractional Order PI Controller using Water Cycle Algorithm parameters obtained by water cycle algorithm (WCA) are KP=0.2179, KI=11.7736.The outer loop fractional order PI controller (FOPI) parameters obtained by WCA are KP=0.3713, KI=1.9075 and λ=1.0006

Summary

Introduction

The power electronics converters are being used at all levels in power systems using renewable energy sources. The most commonly used power converter topology is the three phase voltage source converter. This converter is popular due to its capability to operate either as a rectifier or inverter. In rectifier mode, it is more commonly called as PWM rectifier. The attractive features of these rectifies are better control of dc voltage, nearly unity power factor operation (grid voltage and current in same phase) and less harmonic content in grid current. One of the popular control method known as voltage oriented control (VOC) provides the active and reactive power control indirectly. VOC provides satisfactory response, the operation is largely affected by the chosen current controller [1]. Fine tuning of PI controller is necessary to get satisfactory steady and dynamic response

Methods

Results

Conclusion