Sistema fotovoltaico utilizando um conversor monofásico-trifásico com condicionamento ativo de energia para aplicações em redes monofásicas rurais

Abstract

This work proposes a photovoltaic system connected to an inverter with single-phase input and three-phase output, with universal filtering capabilities. This system is able to inject the energy extracted from the photovoltaic system on the electrical grid, to condition the energy drained of the grid to provide the loads and to supply the three-phase four-wire or three-phase four-wire loads. In addition, current injectec/drained of the grid are sinusoidal and with low power factor, voltage harmonic suppression and voltage sag/swell compensation are achieved, such that the three-phase output voltages are balanced, regulated and sinusoidal with low harmonic contents. The power system is composed by four half-bridge PWM inverters. The topology of the single-phase to three-phase UPQC is composed of four half-bridge PWM converters coupled to a common DC-link. In this topology, one of the half-bridge converters is used to implement the series inverter, which operates as a sinusoidal current source synchronized with the utility voltage. The other three half-bridge converters are connected in parallel to the load. The PV array is connected directly to the DC-link. To maximize the energy drained from the photovoltaic panel is implemented the Observe and Perturb (P&O) MPPT. To the generation of the single-phase reference current is used a SRF algorithm, which receives information from: loads currents, a PLL system, DC-link voltage compensation current, and feedforward current. To the generation of the three-phase reference voltage is used the peak value and the PLL system. To control the systems, a control strategy based in resonant controllers in the state space was developed. The state-feedback gains were obtained by the LQR (Linear-Quadratic Regulator) method. Simulation results are presented to evaluate the performance of the system.