Analysis and optimisation of mechanical equipment maintenance in a hydroelectric power plant

Avtor analizira vzdrževanje turbinskih agregatov in ključne podporne opreme v hidroelektrarni HE Ožbalt (Dravske elektrarne Maribor). Na podlagi delovnih nalogov, tipičnih okvar in intervjujev z vzdrževalci oceni učinkovitost obstoječih praks in predlaga optimizacijo z vidika zanesljivosti, razpoložljivosti in manj nenačrtovanih izpadov.

The theoretical part links maintenance types (preventive, corrective, condition-based), the TPM and RCM approaches, the MTBF, MTTR and availability indicators and the ISO 55000 standard with the practice of annual unit overhauls. A calculation shows that a 25 % blockage of the intake screens over four hours alone costs about 24.73 MWh. The proposed measures are feasible within the existing system.

Problem

A hydroelectric plant generates only when the unit is running – every unplanned outage means a direct loss of electricity from a renewable source. At the Ožbalt plant, maintenance is carried out by in-house staff in an annual overhaul cycle, but work-order records are inconsistent and failure data are not analysed systematically.

• recurring failures of the governor and hydraulics (oil cleanliness), sensors and electrical control assemblies
• auxiliary equipment (trash-rack cleaning machine, gantry crane) determines whether the screens can be cleaned and the flow maintained
• without standardised records, response times cannot be measured and improved

Solution and method

The author combines analytical, descriptive and comparative methods with field observation. He reviews internal documentation, work orders and intervention reports from recent years, groups them by assembly (turbine unit, gantry crane, cleaning machine) and compares existing practices with the TPM and RCM approaches and the principles of ISO 55000. He summarises the situation in a SWOT analysis and a comparison table of the current state and proposed improvements, and substantiates the importance of screen cleaning with an engineering calculation for a unit with a rated output of 24.73 MW.

Rezultati

The thesis confirms three of the four hypotheses (TPM/RCM, digitalisation of records, room for better failure management) and partly the fourth (ISO 55000). The calculation for four hours of operation shows a loss of about 24.73 MWh at medium (25 %) and about 49.46 MWh at severe clogging (50 %, alarm state). Proposals: a more reliable cleaning machine and gantry crane, standardised work-order records, oil-cleanliness monitoring through analyses, systematic tracking of wear parts, stronger preventive maintenance of electrical control and measuring components and gradual digital support for maintenance analysis.