Dynamic Performance of a Wind Turbine Based on a Self-Excited Induction Generator

The paper is devoted to the study of the dynamic performance of a wind turbine in a remote site microgrid based on a self-excited induction generator (SEIG) during sudden load connection. A dynamic model of the currents of the SEIG in the stationary reference frame dq axis is introduced and the main effect of saturation flux in the SEIG is explained. The case of self-excitation with different capacities and connected with purely resistive and inductive loads are discussed in this paper. Keywords: Renewable Energy, Induction Generator, Islanded Wind, Modeling, Self-Excited Induction Generato

Robust three degrees of freedom based on H∞ controller of voltage/current loops for DG unit in micro grids

This study proposes a cascaded voltage–current robust control strategy for a distributed generator (DG) in microgrids. The main objective of the proposed controller is to improve the performance and power quality of a DG by injecting simultaneously a good sinusoidal voltage/current to the different loads connected to the DG. The proposed cascaded voltage/current controller consists of three degree-of-freedom controller, which is designed by using H∞ control theory based on mixed sensitivity specifications. The choices of appropriate weighting functions Wt, Wu, Wy that satisfy the preset goals to get a robust controller and a transform to a standard H∞ control design problem based on pre-compensator, feedforward and feedback connections are presented. The 3DOF-controller is based on MATLAB R/SimPowerSystems and using RT-EVENTS-toolbox. The controller is evaluated under different scenarios: transient responses with a resistive local load, and loads disturbances in steady-state responses with resistive, resistive inductive, resistive capacitive, and non-linear loads. Simulation and experimental results of resulting waveforms from a DG unit are presented, it confirms the effectiveness of the proposed method in effectively rejecting perturbation and robustness to loads disturbances; both good reference tracking and good transient response, and finally significantly lead to a very low total harmonic distortion

Adaptive hysteresis current control of active power filters for power quality improvement

In power grids, the active power filter (APF) is an important device for compensation of harmonic pollution and reactive power caused by nonlinear loads. However, the control method has a significant influence on the APF performance in eliminating the distorted currents. Henceforth, this paper explores the control of shunt active power filters based on: 1) instantaneous power control strategy (p-q Theory) for extracting the reference currents for APF, and 2) adaptive hysteresis current control (AHCC) strategy for performance evaluation. Different case studies are carried out such as, balanced/unbalanced source with balanced/unbalanced load, distorted source with balanced load in Matlab®/ SimPowerSystems. Simulation results highlight the effectiveness of the proposed control method

A novel Decoupled Trigonometric Saturated droop controller for power sharing in islanded low-voltage microgrids

This paper proposes a novel droop control based on Decoupled Trigonometric Saturated (DTS) controller for stable power sharing applied to meshed parallel inverter systems in islanded microgrids. The novel DTS control scheme is introduced to improve the power-sharing accuracy with a better stability and to provide a proper dynamic decoupling of active and reactive power in the presence of different impedances. Moreover, this method not only achieves the aforementioned decoupling; but also, guarantees both voltage and frequency stability. The theoretical concept of the proposed novel droop control strategy is presented in detail. The DTS controller is applied to a common AC bus microgrid structure and a meshed parallel inverter system structure in islanded microgrids with mainly inductive or resistive line impedances. An offline time-domain simulation is conducted in MATLAB®/SimPowerSystems environment using RT-EVENTS toolbox from OPAL-RT to model the inverters. Resulting waveforms from a three-phase microgrid with four distributed generators are presented along with a comparison against the conventional droop control strategy and show the effectiveness of the proposed method in allocating both real and reactive power