Avaliação de estratégias de controlo de tensão em redes de baixa tensão com unidades de microgeração

Increasing worldwide pollution levels and the emission of greenhouse gases have brought severe negative effects to the environment, with climate change and global warming being one of the biggest warning signs against the non-sustainable growth of Humanity. As a consequence, the Electrical Energy Systems (EES) have been facing significant changes, in order to further the production of clean and renewable electrical energy. The last decades have since witnessed a huge development of new and better technics for endogenous energy exploitation, aiming for an increase in its efficiency and supply safety. One of the products of this development has been the creation of low power energy production systems, whose increasing technological maturity has allowed regular Low Voltage (LV) customers to afford these Microgeneration (μG) systems. Besides producing renewable energy, this type of Distributed Generation (DG) also has numerous operational advantages for the grids. However, the passive integration of microgeneration in the LV distribution grids has been troublesome, introducing several negative impacts and disadvantages, which can lead to various technical problems if left unchecked. The EES typical organization and structure doesn’t contemplate the inclusion of DG in the transport and distribution grids, assuming the power flow to be unidirectional, beginning in the major production centers, travelling down the superior voltage levels and finishing in the LV end customers. This type of grid organization offers serious inconveniences to microgeneration integration, fueling the creation of a new energy paradigm, who molded the planning and structuring of the electrical grids around maximizing DG integration. Pertaining to the LV distribution grids case, the fact that these grids are characterized for being highly resistive, establishes a direct coupling between active power and voltage, meaning that the power produced from microgeneration generates a rising voltage effect so serious, it may even infringe the voltage technical limits in place, limiting the amount of microgeneration that can be installed. For this reason, new notions of LV distribution grids have been studied based on a Smart Grid (SG) concept, which together with the microgrid (MR) and multi-microgrid (MMR) concepts have brought a new purpose of maximizing the amount of μG distribution grids can integrate, by efficiently managing all Distributed Energy Resources (DER) connected to them. This is possible through the use of an advanced communication and control infrastructure, which allows the implementation of numerous voltage control strategies. These voltage control strategies differ in concern to their usage of the resources made available in a SG scenario, being often grouped as local or coordinated control. Under a local control strategy, local information is used in order to exact a control that despite being easy and simple to implement, is often non-optimal and not dynamic. On the other hand, the coordinated control makes use of all the resources a SG offers, in order to obtain a general view of the grid and measurements of all its controllers, as to provide a truly optimal and global solution. Energy storage devices, despite being simple DER, are special in regards to their ability to play many roles, both in support to other voltage control strategies, and in order to implement a voltage control itself.