In an era when renewable energy sources are becoming the backbone of power generation, ensuring the reliability of key components such as lower-voltage generator step-up transformers (LV-GSUs) is paramount. A new survey aims to study the performance and reliability of LV-GSUs, says Ian Gray of Oilwatch Transformer Service.
In response to the global energy transition, thousands of LV-GSUs have been installed in renewable energy plants such as wind farms and solar photovoltaic (PV) parks over the past decade.
Unlike conventional GSUs used in large power plants, the LV-GSUs operate at significantly lower power ratings and voltages, superficially resembling standard distribution transformers. However, their operating conditions are different, involving fluctuating loads and high harmonics from inverter systems, compared to the high load factor and quasi-sinusoidal waveforms of traditional generator sets.
Therefore, the design and insulation systems of LV-GSUs vary considerably from conventional GSUs. LV-GSUs can be either liquid-type or dry-type transformers with epoxy resin insulation. For liquid-insulated systems, alternative fluids such as natural or synthetic esters, combined with thermally upgraded or aramid paper, are often used. Failures in these transformers can lead to power interruptions with offshore installations facing particularly high costs for installation, repair or replacement.
In recent years, multiple failures of LV-GSUs have been reported, raising concerns about their reliability compared to conventional transformers.
CIGRE study
The International Council on Large Electric Systems (CIGRE) has launched a study to better estimate the failure rates, reliability and root causes of failures in LV-GSUs. This research aims to develop recommendations for future specifications, design parameters and testing improvements. If specific failure causes are found to be prevalent, additional working groups may be established.
Led by Professor Peter Werle of Leibniz University Hannover, the CIGRE working group is looking for operators and owners of onshore and offshore wind and PV parks to share their data anonymously. Local efforts are spearheaded by Professor Jan de Kock with support from the CIGRE Southern Africa Regional Advisory Group.
