Renewable energy was responsible for producing this year around 59% of the total amount of electricity in Portugal and it is expected that 1/3 comes from wind energy sources, according to data disclosed by APREN. It becomes more and more crucial to support alternative solutions to produce energy, a topic that was highlighted on the 2016 Portuguese Association of Renewable Energies Award which has honoured Bernardo Marques Amaral Silva, a INESCTEC researcher and a MIT Portugal Program Sustainable Energy Systems Phd doctorate at the Faculty of Engineering of the University of Porto with the first prize for his thesis "Multi-terminal HVDC Grids: Control Strategies for Ancillary Services Provision in Interconnected Transmission Systems with Offshore Wind Farms" , a pioneering approach to take the best profit of Wind farms (WF).
Wind Energy (WE) has largely contributed to the de-carbonisation of the energy sector and consequently to the de?nition of the European Commission (EC) targets on renewable-based electricity generation. During the last decade, massive investment has culminated in the substantial installation of Wind Farms (WF). Moreover, the ambitious plans for increasing these targets on renewable-based electricity generation demand the deployment of more WF. However, the European Union has settled the goal for the level of greenhouse gas reduction by 40% (by comparison with 1990 levels) until 2030 and the share of renewable energy to 27% in terms of energy consumption.
Simultaneously, the Fukushima incident has put pressure on European governments regarding the use of nuclear power plants which, although not considered as renewable, have reduced emission of greenhouse gases (compared to conventional power plants based on fossil fuels).
In order to meet the new goals, it is expected a significant contribution from offshore wind farms (at sea). From a technical point of view, the adoption of High Voltage Direct Current (HVDC) is crucial to allow the installation of high power PE and to manage high connexion distances from the mainland. Recent procedures intend to adopt direct current networks rather than connections "point-to-point" since they may also support the connection between mainland AC networks, allowing a greater integration of renewable sources and enabling the development of a European electricity market.
The work developed by Bernardo Marques Amaral Silva has focused on the development of strategies to control and operate HVDC networks with offshore wind farms, to allow the delivery of support services to the mainland electrical systems, in an autonomous environment without communication system.
In a first phase, a control scheme for allowing offshore WF as well as the interconnected AC mainland grids on participating on primary frequency control has been developed. This control scheme also took into account the need of provision of synthetic inertia by offshore WF. The results showed a successful accomplishment on mitigating an interconnected mainland grid frequency disturbance.
In a second phase, DC grids control schemes were developed and tested aiming at the operation of the DC grid during an AC mainland fault event (Fault Ride-Through - FRT capability) and also to assure the operation of the DC grid following a permanent fault events or the disconnection of an onshore converter.
According to the former MIT Portugal Program student, the major outcome of this project consists on allowing the management of more wind energy production and consequently increasing energy coming from renewable sources. The idea has already been tested in laboratory and its feasibility has been verified so, in a near future, the goal is to test it in an existing wind farm.
The main objective of the second edition of the APREN Award was to support the best and most relevant academic Thesis held in Portuguese higher education institutions (related to renewable electricity) and to contribute to the disclosure and knowledge transfer between Research Centers and companies.