Jaqueline Oliveira Rezende

With a great potential yet to be explored in Brazil, the grid-connected photovoltaic system, besides supplying the active power, can also contribute to improve the voltage level grid providing reactive power. Therefore, this work proposes to use a Grid-Connected Photovoltaic System (GCPVS) equipped with a control that uses the automatic voltage regulator (AVR) to balance the injection of the active and reactive powers, thus softening the short-duration voltage variation, more specifically the momentary voltage dip. For this purpose, the GCPVS was connected in part of a real distribution grid that attend the block 1106 South of Palmas city, state of Tocantins, northern region of Brazil. It is shown that the active and reactive power delivered to the grid can be controlled to help the power quality of the main grid during a disturbance. During a short-circuit situation, the active power is reduced, freeing up space from the inverter capacity for maximum supply of reactive power, in this way, helping the main grid to return to an adequate voltage level. The simulation results show that such voltage profile improvement is possible. Therefore, they confirm that photovoltaic systems, even though considered small, can also provide ancillary services to the low voltage distribution grid during abnormal conditions, adding to the actions normally performed by conventional power plants

The present paper has as its objective to optimize the reactive power in electric systems that have a photovoltaic power plant connected to it, thus aiming at improving the voltage profile of all system buses, so that they meet the values determined in the standard. For this, it is proposed to accurately determine the ideal amount of reactive power, using the genetic algorithm, in which there is no use of approximate equations, reduction of the active power of the photovoltaic source and, moreover, it allows the regulation of the voltage of all the buses in the system, being able to raise or reduce their voltage level. The proposed methodology is validated through the analysis of the 14-bus electric system from IEEE, into which a photovoltaic power plant was connected. Studies were carried out with six different load scenarios in the literature to observe the performance of the proposed algorithm. Through the analysis of the results, one concludes that the developed genetic algorithm is efficient for determining the reactive power values that result in the reduction or increase of the voltage levels of all buses in the system, allowing them to meet the values determined in the regulatory standards.

This article presents a new free and open-source computer platform that is capable of performing power flow simulations, balanced and unbalanced short-circuits, besides transitory and dynamic stability studies with user-defined controls. The software, called Power Systems Platform from the Federal University of Uberlândia (PSP-UFU), has as its goal to aid in the areas of research and education. Through an interface aligned with the CAD tool, the construction of any electric network and control system is permitted by the directing of visual elements. Standard software architecture was used in the development of the platform, as well as standardisation and documentation, which are necessary practices for an understanding into the source code and software development by third parties. The software possesses an excellent computational performance and a friendly and intuitive interface, which all go on to make it ideal for educational applications in electric power systems.

This research has as main objective to analyze the contributions of a distributed generation unit when connected to a medium voltage distribution feeder (13.8 kV). The behaviour this electrical system is evaluated following the occurrence of some disturbances. Before this, all the modelling of the electrical system was performed using ATP - Alternative Transients Program. Three types of disturbances were simulated: phase-to ground short-circuit, islanding of part of the electrical system and load increase on the feeder. To easy the comparisons, all studies were carried out with and without the presence of the distributed generator taking into account the following variables: busbar voltage profile, output power provided by the substation and by the distributed generator when present.