Avaliação da variabilidade de potência de um sistema híbrido eólico- fotovoltaico de geração centralizada

Abstract

The growing demand for electric energy, coupled with environmental concerns, has increased the use of renewable sources of energy on the electric matrix, with solarphotovoltaic and wind generation being the most notable. The wind and photovoltaic energy sources have been evaluated as the most promising and economically attractive and, due to successive technological advances, it has become widely used at several countries, representing an important portion of installed capacity and with several large plants as highlight. However, the generation of energy from these sources depends directly on solar irradiation and wind speed, which have a stochastic behavior, resulting in greater variability in the power generated and, consequently, can cause problems in the quality of electricity and affect the safe and stable operation of the electrical power system. The aforementioned power variations can be classified according to the time scale which it occurs. Short-time variations are those that occur on the scale of seconds and minutes, and long-time variations are those that occur on the scale of hours to days. As a result of the problems introduced by the power variability, solution has been adopted to mitigate the effects, being the hybrid connection of these systems an option. The hybrid generation of a photovoltaic system with a wind system is a solution to mitigate the power variability caused by a photovoltaic power plant or a wind power plant, given the complementary characteristics of these two resources, in such a way that the hybrid connection would improve reliability and result in more economical operation. However, it is necessary to quantify how the hybrid power plant of photovoltaic with wind system reduces the power variations in relation to the single system, in order to evaluate the power variations magnitudes and power variation rates of the three large systems. The evaluation of the wind-photovoltaic system is performed using simulations on MATLAB® and Simulink considering photovoltaic and wind power plants models that have realistic behavior. The solar irradiation signals are generated using fractal theory to emulate the shading caused by clouds. The wind speeds used are originals from measured data, which are emulated in order to introduce the effects of time delay and damping. In this way, the power variation of the systems was evaluated for different conditions, where in the scenario with the bigger maximum percentage power variation observed, the hybrid power plant showed a maximum variation of 15,67%, while the photovoltaic power plant showed 28,05%, this means that the hybrid connection mitigate the power variation. With these results, it will be possible to verify the scenarios in which the hybrid system will be able to mitigate power variations when compared to the single systems.