Nowadays, a significant number of distribution systems are facing problems to accommodate more photovoltaic (PV) capacity, namely due to the overvoltages during the daylight periods. This has an impact on the private investments in distributed energy resources (DER), since it occurs exactly when the PV prices are becoming attractive, and the opportunity to an energy transition based on solar technologies is being wasted. In particular, this limitation of the networks is a barrier for larger consumers, such as commercial and public buildings, aiming at investing in PV capacity and start operating as microgrids connected to the MV network. To address this challenge, this paper presents a coordinated approach to the microgrid investment and planning problem, where the system operator and the microgrid owner collaborate to improve the voltage control capabilities of the distribution network, increasing the PV potential. The results prove that this collaboration has the benefit of increasing the value of the microgrid investments while improving the quality of service of the system and it should be considered in the future regulatory framework.
KeywordsDistribution grid voltage control, microgrid design, model predictive control, photovoltaics.
IntroductionThe number of photovoltaic (PV) installations have exponentially increased over the last decades and a more accelerated growth, pulled by the emerging economies, is expected by In addition, in order to maximize the on-site DER penetration it is a common practice to apply Demand Response (DR) procedures to decrease the load in peak hour conditions, These technical approaches to improve grid controllability proved to be very efficient in increasing the capabilities of distribution systems to host more PV capacity. However, they entail investment and operational costs to the distribution system operators (DSO) and, especially in scenarios of unbundling electricity sectors, DSOs have no interest in making those investments and bearing those costs. In fact, they have no motivation to enable more PV capacity, since their remuneration depends on electricity consumption and the 6 challenges of solar integration are mostly peak power related [19]. Moreover, the installation of photovoltaic units has the practical effect of reducing the net consumption of the prosumers, which decreases the income of the DSOs.The difficulties of the system to accommodate more solar power persist in most distribution networks, especially those that already have a considerable number of photovoltaic installations connected to the LV network. This is a particular barrier for larger consumers, such as commercial and public buildings, aiming at investing in PV capacity and start operating as microgrids connected to the MV network (e.g., [26] and [27]). Three main reasons explain the limitations imposed by the distribution grids to the microgrids investment and planning process: 1) microgrids require a significant amount of PV to justify the investments and, since all the capacity is conc...