Estratégia de controle volt/var em redes elétricas inteligentes por inversores fotovoltaicos

Abstract

This paper presents a study for the implementation of an hierarchical Volt/Var control (VVC) strategy using the frequency inverters which make the connection between photovoltaic distributed generation (DG) and the electrical grid, with the objective of improving distribution network voltage levels. The VVC is a fairly used procedure within distribution systems, traditionally implemented through equipment such as capacitor banks and voltage regulators, and is based in the use of reactive power to regulate the voltage at all the system buses. This way, the technological advances regarding smart grids have been inflicting big changes in the way such systems work, by the likes of the expansion on computational and communication methods at the same time the presence of DG grows more each day. Therefore, although the many benefits DG can bring, its presence is a known factor for worsening the grid’s voltage levels, due to the intermittence of renewable energy sources and the reverse power flow problem caused by DG. Frequency inverters are equipment based on power electronics and, due to this, don’t lose their lifespan when performing the control commutations necessary for VVC, showing, in this aspect, an advantage to traditional control equipment. To summarize, implementing VVC through the photovoltaic inverters that connect GD to the electrical grid represents a huge benefit to the system, not just by the surplus on traditional control equipment’s lifespan but also due to the high growth of distributed energy resources presence and the improvement on the voltage levels. This paper’s proposed methodology foresees the use of a local control, aiming to establish an easy and agile implementation for power distribution companies, in order to improve voltage levels on electrical networks with photovoltaic DG. Keywords: Photovoltaic Distributed Generation; Smart Grids; Smart Inverts; Volt/VAr Control.