This paper presents the analysis, design, and experimentation results of a photovoltaic energy management system with battery backup. The proposed system is capable of both grid-connected and islanded operations. The main advantage of the proposed system is that, in grid-connected mode, the inverter works as a current source in phase with the grid voltage, injecting power to the grid and controlling the dc-link voltage. The dc/dc converter manages the battery charge. In islanded mode, the inverter control is reconfigured to work as a voltage source using droop schemes. The dc/dc converter controls the dc-link voltage to enable the maximum power point tracking reference to be followed. An operation protocol is proposed to ensure the quality of the energy supply and minimize energy loss. A battery bank is connected to the dc link as energy storage for islanded operation mode. The aim of this paper is to show that the proposed system performs correctly, without dangerous transients for the inverter or the loads. Simulation and experimental results on a 3-kW prototype show the feasibility of the proposed control strategy.

This paper presents a review of the power and torque coefficients of various wind generation systems, which involve the real characteristics of the wind turbine as a function of the generated power. The coefficients are described by mathematical functions that depend on the trip speed ratio and blade pitch angle of the wind turbines. These mathematical functions are based on polynomial, sinusoidal, and exponential equations. Once the mathematical functions have been described, an analysis of the grouped coefficients according to their function is performed with the purpose of considering the variations in the trip speed ratio for all the coefficients based on sinusoidal and exponential functions, and with the variations in the blade pitch angle. This analysis allows us to determine the different coefficients of power and torque used in wind generation systems, with the objective of developing algorithms for searching for the point of maximum power generated and for the active control of wind turbines with variations in the blade pitch angle.

This paper presents a review of different mathematical models of both the power coefficient and torque coefficient in wind turbines. These coefficients are used to realize the analysis of a wind turbine, depending on the type of turbine, which is used. The coefficients of power and torque establish the relationship between wind power and power obtained in the turbine. In the review were found various models, the goal of this paper is to classify to find a general model, however, due to the characteristics of the models found, the models were classified into three general groups. Each group was classified according to their mathematical expression, which was exponential, sinusoidal and polynomial. The exponential and sinusoidal models include variations in relation to the specific speed and the pitch angle; and the polynomial models only depend on the specific speed. The models consider the real characteristics of wind turbines. The purpose of this review is to establish mathematical models of power coefficient and torque coefficient, in order to evaluate different models of wind turbines on the emulator.

Unavoidably, the controlsystem of any permanent magnet synchronous motor (PMSM) is subjected to perturbations, e.g., motor nonidealities and inverter nonlinearities. To reject these perturbations, a new super-twisting (ST) control variant, called speed adaptive super-twisting (S-AST) control, is proposed in this paper. In the S-AST control, a proportional-integral (PI) and a ST controllers are merged using an adaptive law that is based on the motor speed measurement. This is done to reduce the chattering problems that the standard ST control presents. In addition, a mathematical design for the S-AST control is proposed, where the relationship between the chattering amplitude, the switching frequency and the system perturbations is shown. The main contribution in this paper is the application of the S-AST controller to reduce the total harmonic distortion (THDi) of the PMSM currents. By comparing the S-AST control against PI control, the THDi is reduced from 9.9% to 1.27%, in simulation, and the THDi is reduced from 22.79% to 1.56%, experimentally. These results demonstrate how the S-AST control is an excellent alternative to improve the waveform of the PMSM currents.