In an era where electricity demand continues to soar and our power infrastructure ages, the global electrical power system stands at a critical juncture. Today, we’re witnessing the formation of what could become the world’s first truly global electric power system, with ultra-high voltage (UHV) transmission lines stretching across continents. However, this exciting development comes with its own set of challenges, particularly regarding one of the most crucial components of our power infrastructure: large power transformers.
The Rise of Ultra-High Voltage Transmission
China has emerged as a pioneer in ultra-high voltage transmission, successfully operating 1,000 kV transmission lines since 2009. This achievement marks a significant milestone in power transmission technology, enabling the efficient distribution of electricity across vast distances. The country now boasts eight 1000 kV alternating current transmission lines, spanning approximately 5,310 kilometers.
However, the journey toward high-voltage transmission began much earlier. The Soviet Union led the initial charge in the 1950s, with the United States and Canada following suit in the 1960s. These early innovations laid the groundwork for today’s advanced power transmission systems.
The Aging Infrastructure Crisis
While we celebrate these technological advances, a looming crisis demands our attention. Of the approximately 400,000 large power transformers operating worldwide (rated at 100 MVA or higher and 100 kV or above), more than half have exceeded 30 years of service. This aging infrastructure presents a significant reliability challenge for power utilities globally.
The situation is particularly concerning in some regions. For instance, American Electric Power reports that 33% of their transformers are 50 years or older, with nearly 18% exceeding 60 years of service. The failure rate of these transformers increases dramatically after they reach 40 years of age.
The Reliability Challenge
Industry experts predict that the annual failure rate of large power transformers could soon exceed 2%. More worryingly, newer transformers (those less than 30 years old) are expected to fail at an increasing rate due to reduced safety margins – a consequence of manufacturers prioritizing cost reduction over reliability in recent decades.
While there are exceptional cases of transformers lasting beyond their expected lifespan (such as the remarkable Belgian transformers at Dneproges-1 that have operated for over 80 years), these are outliers rather than the norm. The reality is that most power utilities face the inevitable need for massive transformer fleet renewal.
Looking Ahead: Solutions and Challenges
Several approaches exist to address these challenges:
- Preventive replacement of aging transformers
- Rapid refurbishment and upgrading of units nearing end-of-life
- Online maintenance and modernization
However, each of these solutions comes with its own technical and financial limitations. The experience of the Bratsk HPP in the former USSR, where generator step-up transformers were replaced after their standard 25-year service life, proved to be prohibitively expensive when attempted elsewhere.
The Path Forward
As we move toward a more interconnected global power grid, the need for reliable transformer infrastructure becomes increasingly critical. The foundations are being laid for what could become a world electricity market – potentially rivaling oil in global economic importance.
For utilities and manufacturers, this presents both challenges and opportunities. The development of new specifications for transformers must ensure both reliability and longevity, aiming for a minimum service life of 40 years. Additionally, the industry needs better access to historical failure data and current condition assessments to improve future designs and maintenance strategies.
The fourth industrial revolution brings with it the potential for greater information sharing and transparency regarding transformer operations and failures. This openness, pushing aside traditional corporate secrecy, could lead to improved reliability across the entire power system.
As we look to the future, the role of power transformer engineers and specialists becomes increasingly crucial. Their expertise will be essential in developing specifications for new transformers that can meet the demands of our evolving global power infrastructure while ensuring reliability for decades to come.
Reference:
[1] S. P. Filippov, Mastering ultra-high voltage as – the basis for globalization of electricity supply, Energy policy, 31 Oct 2019 (in Russian), [Online] available at https://energypolicy.ru/osvoenie-ultravysokogo-napryazheniya/neft/2019/20/31/
[2] A. K. Lokhanin, Reducing the insulationlevels of power transformers of the highest voltage classes, Electrotechnika,No. 12, 1991, pp .6–8 (in Russian)
[3] A. Bossi et al., An international survey on failures in large power transformers in service, CIGRE Working Group 12.05, Electra, Vol. 88, pp. 21–48, 1983, [Online] available at https://e-cigre.
org/publication/ELT_088_1-an-international-survey-on-failures-in-large-power-
transformers
[4] CIGRE WG A2.37, Transformer Reliability Survey, Brochure 642, Paris, 2015, [Online], available at https://e-cigre.org/publication/642-transformer-reliability-survey
