Direct active and reactive power control of DFIG based WECS using PI and sliding mode controllers

Abstract

This paper presents a power control study of a Wind Energy Conversion System (WECS) based on a DoublyFed Induction Generator (DFIG) connected to the electric power grid. Proportional-Integral (PI) and Sliding Mode (SM) controls are used to compare the system's performances in terms of reference tracking and robustness to disturbance rejection and with respect to the machine parameters variation. The DFIG control method is based on vector direct control loop with stator flux orientation and the active and reactive powers are controlled PI and sliding mode Simulation studies were performed using Matlab/Simulink/ SimPowerSystems software.

Direct Power Control Optimization for Doubly Fed Induction Generator Based Wind Turbine Systems

“…The dynamical model of the studied DFIG can be expressed by the following electrical equations [6][7][8]:…”

“…Considering that the electrical network is stable, the stator flux ϕ s is constant. In addition, for the medium and high power DFIG, the value of the stator resistance is very small and therefore it can be neglected [6,7]. Hence, based on these assumptions, the stator voltages and fluxes in Equation 3and Equation (4) can be rewritten respectively as follows:…”

“…The conventional control scheme of the grid connected DFIG wind turbine system is built based on a vector control method [5][6][7][8]. Here, the Stator Flux Orientation (SFO) scheme is selected for DFIG power regulation at the RSC.…”

“…The SFO-based vector control strategy enables a decoupled regulation of the active and reactive powers that is flowing between the DFIG and the grid. The active and reactive powers' control strategy is performed by regulating the converter currents using Proportional-Integral (PI) controllers [5][6][7][8]. On the other hand, the Voltage Oriented Control (VOC) is adopted at the GSC, which the DC-link voltage is maintained to constant value [9].…”

“…The gains of the PI controllers that verify the design condition are selected for control loop. However, Hamane et al [6] performed the direct power control of the DFIG using both PI and sliding mode controllers. The synthesis of the PI controller is based on an algebraic pole compensation method.…”