A direct power control of a DFIG based-WECS during symmetrical voltage dips

Sara Mensou,Ahmed Essadki,Badr Bououlid Idrissi,Tamou Nasser

doi:10.1186/s41601-019-0148-y

Abstract

The Wind Energy Conversion System (WECS) based Doubly Fed Induction Generator (DFIG) has experienced a rapid development in the world, which leads to an increasing insertion of this source of energy in the electrical grids. The sudden and temporary drop of voltage at the network can affect the operation of the DFIG; the voltage dips produce high peak currents on the stator and rotor circuits, without protection, the rotor side converter (RSC) will suffer also from over-current limit, consequently, the RSC may even be destroyed and the generator be damaged. In this paper a new Direct Power Control (DPC) method was developed, in order to control the stator powers and help the operation of the aero-generator during the faults grid; by injecting the reactive power into the network to contribute to the return of voltage, and set the active power to the optimum value to suppress the high peak currents. The DPC method was designed using the nonlinear Backstepping (BS) controller associated with the Lyapunov function to ensure the stability and robustness of the system. A comparison study was undertaken to verify the robustness and effectiveness of the DPC-BS to that of the classical vector control (VC) using Proportional-Integral (PI) correctors. All were simulated under the Simulink® software.

Highlights

The evolution of renewable energy is the best solution to protect the environment and reduces the pollution caused by nuclear energy and fossil resources, renewable energy sources come from: wind energy, sun, geothermal, biomass, marine energy and hydroelectric
We develop a new Direct Power Control (DPC) strategy using the nonlinear Backstepping technique to help the operation of the system, ensure the continuity of service, and the connection to the network during and after the symmetrical voltage dips
4 Results and discussions The simulation of the wind energy system under voltage dips was performed using Simulink® software, all simulations were realized whit a doubly fed induction aerogenerator of 1.5 rated power, which the parameters of the generator and the wind turbine are given in the appendix

Summary

Introduction

The evolution of renewable energy is the best solution to protect the environment and reduces the pollution caused by nuclear energy and fossil resources, renewable energy sources come from: wind energy, sun, geothermal, biomass, marine energy and hydroelectric. The crowbar circuits protection are the most popular solution, the principle of this technology, is to connect directly a resistance bank to the rotor of the DFIG when voltage sag is detected, and the doubly-fed induction generator becomes likes a squirrel cage machine [3, 18, 19], that make the generator consumes more reactive power, which leads to voltage instability [20] This solution limits the high current transient and protects the power converter, but the controllability of the generator becomes impossible [17], so the control of reactive power is lost under the crowbar operation. In order to validate and analyze our proposed strategy, the aero-generator dynamic model of a rated power of 1.5 kW and DPC-based Backstepping approach were implemented, simulated, and compared whit VC control under symmetrical voltage dips using Simulink® environment.

Doubly-fed induction generator under voltage dips

Direct power control based-Backstepping technique

Results and discussions

Conclusion