Abstract-The introduction of microgrids in distribution networks based on power electronics facilitates the use of renewable energy resources, distributed generation (DG) and storage systems while improving the quality of electric power and reducing losses thus increasing the performance and reliability of the electrical system, opens new horizons for microgrid applications integrated into electrical power systems. The hierarchical control structure consists of primary, secondary, and tertiary levels for microgrids that mimic the behavior of the mains grid is reviewed. The main objective of this paper is to give a description of state of the art for the distributed power generation systems (DPGS) based on renewable energy and explores the power converter connected in parallel to the grid which are distinguished by their contribution to the formation of the grid voltage and frequency and are accordingly classified in three classes. This analysis is extended focusing mainly on the three classes of configurations grid-forming, grid-feeding, and gridsupporting. The paper ends up with an overview and a discussion of the control structures and strategies to control distribution power generation system (DPGS) units connected to the network.

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.

No abstract

No abstract

No abstract

Voltage fluctuations due to random load variation are amongst the most important power-quality problem in a self-excited induction generator (SEIG) and wind energy conversion system. This paper presents a comprehensive modeling analysis and control strategy of a three-phase cage induction machine used as a self-excited induction generator. The proposed load voltage control strategy is based on the action of the static synchronous Compensator (STATCOM) which can not only provide the necessary reactive power but also may enhance the load ability. Moreover, a feed forward control method for the STATCOM is introduced and applied for controlling the SEIG's terminal voltage by using an outer control loop. An inner loop was also used to control the STATCOM's output reactive power to achieve the regulation of the AC bus voltage during load variation. To achieve this objective, we have designed and introduced an RST inner loop controller. To demonstrate the effectiveness of the proposed RST controller, a comprehensive set of simulation results are presented and thoroughly discussed in comparison with those of two other classical controllers, namely, the proportional-integral controller and the integral-proportional controller.

This paper presents the description, analysis and control of an LLC resonant inverter suitable for induction heating applications. The output power of the proposed inverter has to be controlled by adjusting the duty cycle of the switches using a power loop circuit based on fractional order PI λ controller. A phased locked loop (PLL) is used as frequency tracking control circuit. The complete closed loop control model is obtained using small signal analysis. The validity of the proposed control is verified by simulation results. Results of this simulation are compared to those obtained by using a PI controller. They show that the improved PI λ controller exhibits a much better behaviour.

<span>Wind turbines components work as nonlinear systems where electromechanical parameters change frequently [1], which makes nonlinear control an interesting solution to prevail good efficiency. SMC has been largely used in electrical power applications because it offers interesting features like robustness to parametric uncertainties and external disturbances, to conquer the biggest drawback of the SMC, adaptation strategy consists on updating the sliding gain and the turbine torque to contribute with some important characteristics such as chatter-free performance, heftiness, robustness and secure power system operation. Matlab tests are introduced and compared.</span>