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 Resonant Controllers for Distributed Energy Resources in Microgrids

Motivated by the problem of different types and variations of load in micro-grids, this paper presents robust proportional-resonant controllers with a harmonics compensator based on the internal model principle. These controllers ensure robust tracking of sinusoidal reference signals in distributed energy resource systems subject to load variation with respect to sinusoidal disturbances. The distributed generation resource and the resonant controllers are described using the augmented state system approach, allowing the application of the state feedback technique. In order to minimize the tracking error and ensure robustness against perturbation, a set of linear matrix inequalities (LMIs) are addressed for the synthesizing of controller gains. Finally, results obtained in the simulation for resonant compensators with the distributed energy system are presented, in which the controller is applied to the CC-CA inverter

Structural Analysis and Improved Reactive Power Alignment for Secondary Voltage Control

International audienceThis paper proposes a new strategy for secondary voltage control which is easier to implement and improves the alignment of reactive power of generators The control objectives are revisited from both static and dynamic points of view using the internal model principle. A new alignment strategy for the re-active power generations is proposed along with robust dynamic control. The methodology is applied to interconnected power networks based on real data on EUROSTAG. The simulation results show the performance of the proposed methods to regulate the voltage on the pilot buses at the desired values

Adaptive Interval Type-2 Fuzzy Logic Control of a Three Degree-of-Freedom Helicopter

This paper combines interval type-2 fuzzy logic with adaptive control theory for the control of a three degree-of-freedom (DOF) helicopter. This strategy yields robustness to various kinds of uncertainties and guaranteed stability of the closed-loop control system. Thus, precise trajectory tracking is maintained under various operational conditions with the presence of various types of uncertainties. Unlike other controllers, the proposed controller approximates the helicopter’s inverse dynamic model and assumes no a priori knowledge of the helicopter’s dynamics or parameters. The proposed controller is applied to a 3-DOF helicopter model and compared against three other controllers, i.e., PID control, adaptive control, and adaptive sliding-mode control. Numerical results show its high performance and robustness under the presence of uncertainties. To better assess the performance of the control system, two quantitative tracking performance metrics are introduced, i.e., the integral of the tracking errors and the integral of the control signals. Comparative numerical results reveal the superiority of the proposed method by achieving the highest tracking accuracy with the lowest control effort

A Review on Mode Transition Strategies between Grid-Connected and Standalone Operation of Voltage Source Inverters-Based Microgrids

International audienceMicrogrids technologies are seen as a cost effective and reliable solution to handle numerous challenges, mainly related to climate change and power demand increase. This is mainly due to their potential for integrating available on-site renewable energy sources and their flexibility and scalability. The particularity of microgrids is related to their capacity to operate in synchronization with the main grid or in islanded mode to secure the power supply of nearby end-users after a grid failure thanks to storage solutions and an intelligent control system. The most critical operating case occurs when a sudden transition from grid-connected (GC) to stand-alone operation (SA) happens. During the transition, the system experiences abrupt changes that can result in a malfunction of the control system and a possible failure of the power system. The transition issue attracted considerable attention from researchers. Indeed, many research works are proposed to address this issue by proposing detection and transition techniques that ensure a smooth transition at the islanding time. Although there are several approaches to dealing with this issue, a categorization of the proposed methods in the literature and their differences is useful to assist engineers and researchers working on this topic. Thus, this study proposes a comprehensive review to summarize these approaches and point out their advantages and limitations

Active Disturbance Rejection Control for Distributed Energy Resources in Microgrids

International audienceMotivated by the significant efforts developed by researchers and engineers to improve the economic and technical performance of microgrids (MGs), this paper proposes an Active Disturbance Rejection Control (ADRC) for Distributed Energy Resources (DER) in microgrids. This approach is a nonlinear control that is based on a real-time compensation of different estimated disturbances. The DER operates along with the electrical grid to provide the load requirements. This load has a nonlinear and uncertain character, which presents a source of unmodeled dynamics and harmonic perturbations of the MG. The main objective of this paper is to ensure the stability and the continuity of service of the distributed generation resources by controlling the DC-AC converter. The ADRC as a robust control technique is characterized by its ability to compensate for the estimated total disturbances caused by the load variation and the external unmodeled perturbations to guarantee the high tracking performance of sinusoidal reference signals in the DER system. The ADRC technique is characterized by its nonlinear function, which provides a high robustness to the controlled system. However, in order to simplify the control structure by keeping its high reliability, this paper proposes to replace the nonlinear function with a simple error (termed linear ADRC), compares the impact of this modification on the system performances, and evaluates its operation in the presence of linear and nonlinear load variations. Simulation results are presented to demonstrate the efficiency of the proposed control approach for a three-phase DER