ISEL - Eng. Electrotécn. - Comunicações
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Browsing ISEL - Eng. Electrotécn. - Comunicações by Subject "Ancillary services"
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- Control of PV distributed systems based on three-phase triple inverters to support grids with unbalanced loadsPublication . Fernão Pires, V.; Foito, Daniel; Cordeiro, Armando; Silva, J. FernandoThis paper is focused on the control system for photovoltaic (PV) generators using three-phase triple inverters. These inverters allow for a distributed PV system, and at the same time, they provide AC multilevel operation. The proposed controller is designed to allow the operation of the inverter in a way that it can extend support to the grid with ancillary services. One of the ancillary services that the three-phase triple inverter can support is the injection of unbalanced currents in order to eliminate or attenuate grid load unbalances. Therefore, the proposed topology will be extended to accommodate four wires. The capability of the system to support the grid with ancillary services, especially the compensation of unbalanced loads, the four-wire multilevel topology operation and the proposed controller will be verified through several simulation tests.
- Optimal scheduling of a pumped storage hydro unit in the day-ahead and secondary reserve electricity marketPublication . Lagarto, João; Fernandes, Filipe; Sousa, Jorge A. M.; Santana, João; Martins, BertoAncillary services play a major role in power systems security and stability. The transmission systems operators contract some of these services at minimum cost in competitive markets. This is the case of the secondary reserve market (SRM). Besides the day-ahead market (DAM) generating companies, aiming at maximize their profits, can increase their revenues by selling available capacity in the SRM. This paper presents the solution of a price-taker generating company, owning a pumped-storage hydro (PSH) unit, acting in DAM and SRM. The results were obtained for three case studies: the generating company acts only in the DAM; the generating company acts in both markets with a fixed pumping capacity of the PSH unit; the generating company acts in both markets with a variable pumping capacity of the PSH unit. Results show that higher profits are obtained when acting in both markets with a variable pumping capacity of the PSH unit.