This paper proposes a robust finite control set for doubly-fed induction generator power control. In this way, the proposed robust finite control has two components of the predicted rotor voltage. The first term calculates the voltage considering the rotor current references and the second term is designed considering the mistakes due to parameters’ estimation. The mentioned errors due to parameters’ variations were modeled as rotor current changes. Hence, the controller calculates the predicted rotor voltage considering parameter variations and rotor current references. So that, the minimized cost function selects the voltage vector to be supplied to the rotor of the machine. The influence of the estimation errors for variations on $R_{2}$ and $\sigma L_{2}$ was also investigated. The results obtained in a setup confirm the controller performance.

A Robust Finite Control Set Applied to the DFIG Power Control

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.

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

This paper proposes a Fuzzy Logic Controller for improvement of the steady-state response of a Doubly Fed Induction Generator used in a wind energy system, and governed by means of a Deadbeat Power Controller. The generator mathematical model is consistent with the Stator Flux oriented strategy in the synchronous reference frame. Different simulation scenarios were developed in Matlab/Simulink to evaluate the dynamic and the steady-state responses. In order to obtain experimental results, the simulated scenarios were repeated by means of a test bench and a Digital Signal Processor board. These results demonstrate that the response still follows the power references imposed, despite the fact that the generator parameters ( R r , L s and L m ) were varied in a 30%. A lower steady-state error is also achieved when compared with a Deadbeat and a classical PI controller. All the aforementioned evidence the proper application of this Fuzzy Controller in a wind power system based on a Doubly Fed Induction Generator.

Deadbeat-fuzzy controller for the power control of a Doubly Fed Induction Generator based wind power system.

Direct torque control-based power factor control of a DFIG

Model predictive control (MPC) is a very popular technique for doubly fed induction generator (DFIG), and several MPC topologies have been proposed. However, most of the time, the controller parameters are done in a heuristic way. This paper proposes an analytical method for the design weighting matrices based on the fake algebraic Riccati equation (FARE). The proposed methodology guarantees the control system stability. Furthermore, simulations results were used to choose the desired control horizon and the desired prediction horizon, considering the steady-state error and the computational cost. Moreover, the DFIG vector control model, the MPC theory, and the FARE formulation were presented. Experimental results were shown to endorse the proposed method.

Predictive Power Control for DFIG: A FARE-Based Weighting Matrices Approach

A direct power control for DFIG under a three phase symmetrical voltage sag condition

This research analyses the quality of the electricity produced on photovoltaic systems connected to the power grid in the city of Cuenca (Ecuador). For this, an overview of the literature and the Ecuadorian, American, and European regulations concerning power quality was carried out to determine the regulatory parameters and admissible limits. From the quality records, it is concluded that, in general, there are no power quality problems, except for momentary current imbalances. In one of the cases, violations of voltage parameters, voltage unbalance, current unbalance and flicker were found. The recommended parameters to be included in the Ecuadorian quality standards are individual harmonic distortion and frequency have been registered.

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Mariana Silva Barreto

Papers

A direct power control for DFIG under a three phase symmetrical voltage sag condition

Power Quality Analysis of Photovoltaic Systems