Υβριδικά συστήματα παραγωγής ηλεκτρικής ενέργειας μικρής κλίμακας: η περίπτωση του οικίσκου ελέγχου σταθμού ηλεκτροδίων γείωσης διπολικής διασύνδεσης υψηλής τάσης συνεχούς ρεύματος Αττικής-Κρήτης στη νησίδα Σταχτορρόη Αττικής

Abstract

A lot of autonomous power systems have been designed and operated with different power levels and with special requirements for climatic conditions, availability, operation/maintenance cost, fuel consumption, environmental impacts, etc. In this thesis, new methods of designing an autonomous power system are presented by application to the power supply of the shoreline electrode station for HVDC link. This station will be constructed on the small island of Stachtoroi for the new high voltage direct current (HVDC) link of Attica–Crete in Greece. The general guidelines of the International Council on Large Electric Systems (CIGRE) and of the International Electrotechnical Committee (IEC) for the power system of lighting and auxiliary loads for these HVDC stations are supplied from the medium voltage or the low voltage distribution network, whereas they do not take into consideration the criticality of this interconnection, which will practically be the unique power facility of Crete island. Therefore, the respective instructions for the process of designing the electrical supply of shoreline electrode station for HVDC link are reworded, the power needs of the station are evaluated in detail and the optimal design of an autonomous power generation system is carried out in terms of annual equivalent cost of construction, operation and maintenance through exhaustive testing and sensitivity analysis taking into account a number of technical parameters such as battery aging, discharge depth, solar irradiation variance during the day and year, cost of land occupation by the photovoltaic panels etc. Then, the photovoltaic unit is optimally configured for the required power from a set of photovoltaic panels of general use and inverters taking into account technical constraints, installation costs, lifetime, efficiencies, capital recovery rates, etc. and extend the corresponding results of the previous configuration appropriately. Following, the method of optimal design of an autonomous hybrid power generation system with photovoltaic panels, batteries and diesel generators that operate in the optimum operation point is developed, while in addition other parameters are adjusted, such as the charge-discharge range of the battery etc., applying it similar to the case of the autonomous system with photovoltaic panels and batteries. Finally, the proposed autonomous systems are compared with the classic conventional solutions (use of autonomous systems with diesel generators only, connection to the distribution power network) and it turns out that depending on the user requirements the creation of an autonomous system with either general purpose photovoltaic panels and batteries, or with photovoltaic panels for marine applications, batteries and diesel generators for particularly increased reliability requirements are superior to the classic solutions in terms of total annual equivalent construction - operation - maintenance costs for the respective deflated capital recovery rates.