A Sequential Approach for Gas Turbine Power Plant Preventative Maintenance Scheduling

Abstract

Traditionally, gas turbine power plant preventive maintenance schedules are set with constant intervals based on recommendations from the equipment suppliers. Preventive maintenance is based on fleet-wide experience as a guideline as long as individual unit experience is not available. In reality, the operating conditions for each gas turbine may vary from site to site and from unit to unit. Furthermore, the gas turbine is a repairable deteriorating system, and preventive maintenance usually restores only part of its performance. This suggests a gas turbine needs more frequent inspection and maintenance as it ages. A unit-specific sequential preventive maintenance approach is therefore needed for gas turbine power plant preventive maintenance scheduling. Traditionally, the optimization criteria for preventive maintenance scheduling is usually cost based. However, in the deregulated electric power market, a profit-based optimization approach is expected to be more effective than the cost-based approach. In such an approach, power plant performance, reliability, and the market dynamics are considered in a joint fashion. In this paper, a novel idea that economic factors drive maintenance frequency and expense to more frequent repairs and greater expense as equipment ages is introduced, and a profitbased unit-specific sequential preventive maintenance scheduling methodology is developed. To demonstrate the feasibility of the proposed approach, a conceptual level study is performed using a base load combined cycle power plant with a single gas turbine unit.The deregulation of the electric power market has introduced a strong element of competition. As a result, power plant operators are striving to develop advanced operational strategies to maximize the profitability in the dynamic electric power market.A systematic approach for profit-based outage planning is introduced in Ref. ͓1͔, with consideration given to system performance, the aging and reliability of equipment, maintenance practices, and market dynamics accounting for the price and availability of fuel as well as the generation of revenues in competing markets. A dual time-scale method is developed to project coupled optimal generation scheduling and outage planning for a single operations and maintenance cycle. This paper studies gas turbine power plant maintenance scheduling with consideration given to multiple operations and maintenance cycles. Specifically, the impact of unit aging on maintenance frequency is investigated over the life cycle of power plants.Gas turbine units are widely used for land electric power generation, and maintenance planning has a strong impact on the profitability of a gas turbine power plant. Performance requirements for modern heavy-duty gas turbines necessitate extreme operating conditions for hot gas path components. As a result, these critical components have a limited life span and, more generally, a gas turbine represents an aging system experiencing continuous degradation during its operation. This physical degradation m...

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