Managing the Risks of Adverse Operational Requirements in Power Generation – Case Study in Gas and Hydro Turbines

Abstract

Load demands in power generation for the national or district grid often require turbo-generator sets to operate under adverse operational requirements with respect to maintenance and design ideals. Such instances typically involve turbines operating beyond maintenance schedules or at part load conditions. Part load operations for hydro turbines, in particular, present a set of unique problems. Power generation managers have to manage the risks of machine damage imposed on their engineering assets in attempt to ensure continuing and stable electricity despatch. This paper presents two case studies examining the risks of machine failures from adverse operating requirements and how it could be managed by condition monitoring. One involves gas turbines operating beyond OEM recommended operating hours between maintenance. Blades failures are potential concerns as well. The risks were evaluated and managed with vibration monitoring of the blades passing frequencies. The other case study relates to hydro turbines operating in rough zones at part load conditions dictated by load stabilization requirements of the electricity grid. Measurements of vibrations, draft tube pressures and strain gauging showed distressed conditions when the turbines were operated at part loads. Premature failures were experienced in these units.