Condition assessment of electrical equipment of windfarms is likely one of the most challenging tasks in asset management of power generation. Stresses which come from power electric pulses to harsh environment affects wind turbines electrical components. Additionally wind turbines are expensive and critical components, due long times required to inspect, replace or restore after failure in particular in off-shore installations.
The reliability of electrical systems in the presence of frequency converters may be reduced significantly by the occurrence of Partial Discharges (PD) and voltage/current transients, which can affect the insulation of the electrical equipment installed. Impulse voltage supply gives rise to over-voltages and uneven potential distributions which stress dramatically electrical insulation. It has been demonstrated experimentally that ageing under high-frequency impulse waveforms is accelerated significantly with respect to sinusoidal waveforms.
A growing number of outages in service has increased the awareness of the industry of the necessity of condition monitoring for the electrical equipment almost to the same level as monitoring of the mechanical gear. From commissioning tests to online condition monitoring modern technologies support the change from Time Based Maintenance (TBM) programs at fixed time intervals to Condition Based Maintenance (CBM).
Condition monitoring will help to detect potential sources of problems at a very early stage and to take the relevant countermeasures before irreversible and harmful events take place. Unexpected breakdown, causing long unplanned outages, can be avoided, thus limiting costs due to loss of revenues and repair after failure.