SDRE-Based Integral Sliding Mode Control for Wind Energy Conversion Systems

Bayandy Sarsembayev,Botagoz Mirzagalikova,Ton Duc Do,Kanat Suleimenov

doi:10.1109/access.2020.2980239

Abstract

This paper proposes a novel integral sliding mode control (ISMC) scheme based on numerically solving a state-dependent Ricatti equation (SDRE), nonlinear feedback control for wind energy conversion systems (WECSs) with permanent magnet synchronous generators (PMSGs). Unlike the conventional ISMC, the proposed control system is designed with nonlinear near optimal feedback control part to take into account nonlinearities of the WECSs. The Taylor series are used to approximate the solutions of SDRE. More specifically, the nonlinear optimal feedback control has been obtained by solving continuous algebraic Ricatti and Lyapunov equations. Sliding variables are designed such that reaching phase is eliminated and stability is guaranteed. The proposed control method equipped with high-order observer can guarantee more superior results than linear techniques such as linear quadratic regulator (LQR), conventional ISMC, and first-order sliding-mode control (SMC) method. Increasing the number of terms of the Taylor's series of the proposed control law provides better approximation, therefore the performance is improved. However, this increases the computational burden. The effectiveness of the control method is validated via simulations in MATLAB/Simulink under nominal parameters and model uncertainties.

Highlights

The disadvantages of the traditional energy sources such as high cost, scarcity, and negative environmental impacts have triggered enormous interest to utilize renewable energy sources effectively
The permanent magnet synchronous generators (PMSGs) in the wind energy conversion systems (WECSs) is connected to the wind turbine all the time
To consider the performance of the proposed control method under parameters uncertainties, the stator resistance is increased by 20% and inductance is reduced by 1% (Table 3)

Summary

INTRODUCTION

The disadvantages of the traditional energy sources such as high cost, scarcity, and negative environmental impacts have triggered enormous interest to utilize renewable energy sources effectively. To cope with limitations of linear control methods, researchers have proposed various advanced linear and nonlinear control techniques to improve performance, attenuate disturbance and unmodelled dynamics in the permanent magnet synchronous generator (PMSG)-based WECS. To overcome these challenges in the nonlinear control systems, the methods such as sliding mode control (SMC) referred as variable structure control (VSC) [9]–[13], direct torque control (DTC) [14], optimal control [15], fault-tolerant control (FTC) [16], model predictive control (MPC) [17], hybrid control [18], [19], [22], H-infinity control [23], fuzzy control [24], and neural network based control [25], [26], have attracted most attention of research groups in the field.

PERMANENT MAGNET SYNCHRONOUS

SDRE-BASED NOMINAL CONTROL PART OF CONTROL

GENERALIZED HIGH-ORDER DISTURBANCE

RESULTS AND DISCUSSION

CONCLUSION