Browsing by Author "Etxegarai, Agurtzane"
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Item Comparative analysis of European grid codes relevant to offshore renewable energy installations(2019-03) Robles, Eider; Haro-Larrode, Marta; Santos-Mugica, Maider; Etxegarai, Agurtzane; Tedeschi, Elisabetta; RENOVABLES OFFSHORE; Tecnalia Research & Innovation; POWER SYSTEMSThe purpose of this paper is to highlight the most demanding aspects of grid interconnection of marine energy installations while at the same time providing an updated overview and comparative analysis of the connection requirements of eight European Grid Codes. Therefore, the major issues related to marine energy installations will be summarized as well as the requirements of this type of generation. Besides, the extent to which current Grid Codes include marine energy technologies will be analysed jointly with the need of harmonization of different Grid Codes into a generalised European grid code. Apart from this, several future trends of marine energy technology and its interconnection will be provided for the final discussion.Item Integration of offshore wind energy into an island grid by means of a Multi-Terminal VSC-HVDC network(Institute of Electrical and Electronics Engineers Inc., 2018-05-21) Haro-Larrode, Marta; Santos-Mugica, Maider; Etxegarai, Agurtzane; Eguia, Pablo; Tecnalia Research & Innovation; POWER SYSTEMSIn this paper, the connection of two offshore wind-farms to an island grid through a Multi-Terminal HVDC (MTDC) link is examined. The control strategy of the MTDC grid is validated against several adverse fault cases occurring at the island grid side. For this purpose an electrical grid model based on a medium size island is used to test the control structure of the MTDC link under faults such as voltage dips and frequency deviations. Simulation results are also presented thereby, pointing out interaction issues between control schemes of the MTDC and island grid. Thus, the participation of the MTDC network to increase the flexibility of the interconnected electrical system stands out in the present work.Item Methodology for Tuning MTDC Supervisory and Frequency-Response Control Systems at Terminal Level under Over-Frequency Events(2020-06) Haro-Larrode, Marta; Santos-Mugica, Maider; Etxegarai, Agurtzane; Eguia, Pablo; Tecnalia Research & Innovation; POWER SYSTEMSThis paper proposes a methodology for tuning a supervisory and frequency-response outer loop control system of a multi-terminal direct current (MTDC) grid designed to transmit o_shore wind energy to an onshore AC grid, and to provide frequency support during over-frequency events. The control structure is based on a master–slave scheme and ensures the achievement of frequency response, with specific implementation of the UK national grid code limited-frequency sensitive (LFSM) and frequency-sensitive (FSM) modes. The onshore AC grid is modelled with an equivalent frequency-response model to simulate the onshore AC grid dynamics under frequency deviations. The main innovation of this paper is the development of a methodology for tuning simultaneously two hierarchical levels of a MTDC coordinated control structure, i.e., the MTDC supervisor, given by the active power set point for slave terminal, and the slope of frequency-response functions at onshore terminals. Based on these two hierarchical levels, di_erent strategies are evaluated in terms of frequency peak reductions and change of the frequency order type. Moreover, tuning guidance is given when a di_erent MTDC control structure or di_erent synchronous generator characteristics of the onshore AC grid are considered.Item Performance of a superconducting breaker for the protection of HVDC grids(2020-03-27) Etxegarai, Agurtzane; Larruskain, Dunixe Marene; Iturregi, Araitz; Saldaña, Gaizka; Apiñaniz, Susana; POWER ELECTRONICS AND SYSTEM EQUIPMENTFuture multi-terminal high-voltage direct current (HVDC) grids will be essential for the electric power system expansion. However, there are still several technical, economic and legal obstacles that interfere with the construction of those grids. One of the main technical issues is the interruption of DC currents when a fault occurs, due to the high values of DC fault currents that can exceed the DC circuit breakes (DCCB) interruption capability in few milliseconds. In order to overcome that limitation, a superconducting DCCB (S-DCCB) is presented in this study. The proposed S-DCCB is based on the combination of a superconducting fault current limiter, a mechanical DC circuit breaker and a current limiter reactor. The presented S-DCCB is modelled and simulated by PSCAD/EMTDC software on a four-terminal HVDC system. Its behaviour is proven to be satisfactory for several fault scenarios. DC fault currents are initially limited and afterwards interrupted by the S-DCCB in an operation time that fulfils DC grids' protection requirements.