Desacoplamento P/Q de sistemas de geração distribuída utilizando o conceito de impedância virtual

Abstract

The distributed generation systems based on renewable sources has increased due to a fast return on investment, advances in interconnection systems, and environmental concerns. In Brazil, the distributed generation energy capacity is growing due to the new electric power system model based on distributed generation systems participation and methods to regulate the power flow in generation units. The generation units contribute to electric system stability, especially in low-voltage grids, which is the predominantly resistive and the active power produces overvoltages. In addition, power flow strategies used in conventional generation systems cannot be used in low-voltage systems due to active and reactive power coupling. This paper presents the power flow control on distributed generation photovoltaic system controlled in voltage mode based on virtual impedance concept. In order to overcome the active and reactive power coupling problem, the proposed method is implemented by means a virtual resistor. For analysis purposes, the virtual resistor is implemented by two ways. In the first one, a positive virtual resistor is implemented to accentuate the resistive profile of the system, performing the P/V and Q/θ control. In the second one, a negative virtual resistor is implemented in order to make the network profile predominantly inductive, and then perform the traditional P/θ and Q/V control. The virtual impedance concept technique is evaluated through simulation and experimental results.