Cogenerative Performance of a Wind − Gas Turbine − Organic Rankine Cycle Integrated System for Offshore Applications

Gas Turbines (GT) are widely used for power generationin offshore oil and gas facilities, due to their high reliability,compactness and dynamic response capabilities. Small heavyduty and aeroderivative units in multiple arrangements aretypically used to offer larger load flexibility, but limitedefficiency of such machines is the main drawback. A solutionto enhance the system performance, also in Combined Heat andPower (CHP) arrangement, is the implementation of OrganicRankine Cycle (ORC) systems at the bottom of the gas turbines.Moreover, the resulting GT-ORC combined cycle could befurther integrated with additional renewable sources.Offshore wind technology is rapidly developing and floatingwind turbines could be combined with offshore GT-ORC basedpower plants to satisfy the platform load.The pioneering stand alone power system, for an oil and gasplatform, examined in this paper comprises a 10MW offshorewind farm and three gas turbines rated for 16:5MW, eachone coupled with an 4:5MW ORC module. The ORC mainparameters are observed under different wind power fluctuations.Due to the non-programmable availability of wind and powerdemand, the part-load and dynamic characteristics of the systemshould be investigated. A dynamic model of the power systembased on first principles is used, developed in the Modelicalanguage. The model is integrated with a time series-basedmodel of two offshore wind mills. Various thermodynamicindexes, available in the literature, are identified and evaluatedto compare the actual combined heat and power performancesof single components and of the overall integrated system in theconsidered wind scenarios.