The current microgrid (MG) needs alternatives to raise the management level and avoid waste. This approach is important for developing the modern electrical system, as it allows for better integration of distributed generation (DG) and battery energy storage systems (BESSs). Using algorithms based on artificial intelligence (AI) for the energy management system (EMS) can help improve the MG operation to achieve the lowest possible cost in buying and selling electricity and, consequently, increase energy conservation levels. With this, the research proposes two strategies for managing energy in the MG to determine the instants of charge and discharge of the BESS. A heuristic method is employed as a reference point for comparison purposes with the fuzzy logic (FL) operation developed. Furthermore, other algorithms based on artificial neural networks (ANNs) are proposed using the non-linear autoregressive technique to predict the MG variables. During the research, the developed algorithms were evaluated through extensive case studies, with simulations that used data from the PV system, load demands, and electricity prices. For all cases, the AI algorithms for predictions and actions managed to reduce the cost and daily consumption of electricity in the main electricity grids compared with the heuristic method or with the MG without using BESSs. This indicates that the developed power management strategies can be applied to reduce the costs of grid-connected MG operations. It is important to highlight that the simulations were executed in an adequate time, allowing the use of the proposed algorithms in dynamic real-time situations to contribute to developing more efficient and sustainable electrical systems.

The design of the capacitor bank to be placed with the squirrel cage induction generator, when operating with a direct connection to the distribution system, is performed from the value of the magnetization reactance of the machine. Based on the experimental procedures, the necessary reactive power is simulated according to the induction generator loading. Therefore, with the increase in generated active power, a larger portion of reactive is required. The simulation indicates the values of ideal capacitors. Thus, an analysis is made of which magnetization reactance factor is ideal for the capacitor bank design designated for the generator. The characteristic curve for capacitor bank sizing is related to the load torque loading depending on the active power generated. Thus, this work contributes to the analysis of the self-excitation curve of the three-phase induction generator that operates in parallel with the steady-state power distribution network. Obtaining the active power generated as a function of the absorbed reactive power required for induction generator magnetization can be found.

The main objective of this research is to propose an active and reactive power injection control in order to mitigate voltage sags. The proposed control strategy works in conjunction with a modified version of an automatic voltage regulator (AVR), where it will act on the active and reactive powers injected by the inverter to reduce the effects of voltage sags. In this way, the control will avoid possible shutdowns and damage to the equipment connected to the grid. The voltage improvement can be perceived for consumers connected to the power system. Modifications in AVR model and parameters are performed to speed up its performance, thus identifying the short-duration voltage variations (SDVV) and, consequently, the control acts to alter the powers, decreasing the active power injection and increasing the reactive power based on inverter capacity during the momentary voltage dip (MVD). Finally, when the fault is cleared, all values return to the pre-fault condition, so that the inverter only operates with active power. A 75 kW three-phase grid-connected photovoltaic system (GCPVS) equipped with the proposed control was inserted in a distribution grid of the city of Palmas, state of Tocantins, Brazil, and all of the computer simulations were performed on the Matlab/Simulink^®.

This article proposes the use of a three-phase induction generator (IG), connected through a single-phase connection (Fukami configuration), to be used as a rotating exciter for synchronous generators. This proposal aims at presenting an alternative to replace the permanent magnet generators (PMGs) used in the rotating exciters for synchronous generators (SGs). In order to obtain the results, a six-pole IG and a four-pole SG were used, a DC motor (DCM) was employed as the primary machine, and the speed control for the aforementioned primary machine is presented and described in this work. To carry out performance tests of the rotating exciter with the IG and the terminal voltage control of the SG, a voltage controller was proposed. The performance of the voltage regulator was tested when the SG supplied a dynamic load, as established by the NEMA MG-1 standard. This article validates its proposal by comparing the results obtained through computational simulation and experimental testing of the SG terminal voltage waveform when faced with a sudden load change.