The Availability Model: Consultant's Working Paper Number 32

Abstract

This note describes some results obtained from the Consultant's Availability Model. They are based on preliminary data provided by Y-ard on the reliability of devices, and by Kennedy & Donkin on the transmission scheme. It is estimated that about 20% of the total energy output of a system might be lost due to repairs of its component. (This does not include lossed due to routine maintenance activities) . Assuming a value of 5p/kwh, this is equivalent to a cost of about £40m per annum for a 2gw station. station. There are several possible ways of reducing such losses, however , the most important being: - The reduction of failure rates by improvements in design, added redundancy in critical areas, or additional preventive maintenance. The use of larger numbers of repair crews, boats, etc .. - The reduction of live repair times in order to take advantage of the short weather windows which occur during the winter months, and/or the improvement of access to devices so that repair work can be carried out in more severe sea conditions. The trade-offs which exist between investing money in these areas and the resultant savings in energy losses are discussed, with the conclusion that the optimal solution for any scheme is likely to be one that reduces such losses to a minimum, by capital investment or high O+M expenditure. The appendices give an outline of the Availability Model and a revision of the sea-state information given in Working Paper 24, based on a more extensive analysis of the data