Enel’s vision for future inverters includes monitoring the condition of individual subcomponents, while Southern Power spoke about paying more attention to on-site transformers during their presentation at the O&M PV Operations Dallas 2019 conference. .
Walking on the exhibition floor at Dallas Photovoltaic Operations 2019, which has been coupled with Wind Operations Dallas, pv magazine United States received an excellent education in “state-led maintenance” which takes place a few hundred feet above the ground in wind-powered pods the size of a school bus.
from Enel David Grandi presented a vision of literally listening to the subcomponents within solar inverters, while reporting on the current state of inverter operations and maintenance (O&M).
First of all, it gave a great overview of standard UPS maintenance (image above) – and how it has certain flaws that limit the value of human labor going on. Grandi suggested, ironically, that the greatest value of the above work was not to help the inverters stay healthy – but that it was actually the best to maintain the warranty. The reason: 89% of UPS failures are random, and human interaction with hardware has been a major contributor to hardware failures.
This led to a great discussion of various ideas surrounding state-led maintenance. And what this basically means is that we need to invest earlier in our hardware by making it smarter, in our humans by training them better, and in our tools to choose which ones do the most for us. The investment challenge was one that the solar industry had to consider as it hammered the prices, however, the long term benefits were a more predictable equipment replacement schedule, higher level of education – therefore higher quality, higher wages and lower turnover of – operation and maintenance professionals, as well – of course – greater system availability.
The image above shows some of the tools that have been suggested to better pay attention to inverters. Already we are doing aerial drone thermography to help us analyze the modules, now it is suggested to integrate these types of tools inside the solar equipment. Additionally, Grandi pointed out that we can – literally – listen to the sounds made by the subcomponents and predict their health and potential duration of failure.
Tyler Cromey, refined gentlemen of Southern Power explained from a field experience that projected performance does not always represent reality and how you have to predict the future of hardware if you want to be economically competitive in power generation.
The first reality that Cromey pointed out is the header image of this article – that the reality and the projections are different. For example, the best O&M contract ever is run by human beings, human beings who sometimes have flaws and decide not to clean the top row of solar panels. However, there is much more than humans – there are bird watchers, foxes, squirrels, other rodents and more – and they are part of our industry’s big land use responsibility.
The most interesting preventive maintenance knowledge that has been abandoned has come from transformers. Southern Power has a national solar energy portfolio and a much larger fossil fleet, with over 500 megawatts of solar power that they themselves operate and maintain. During this time, they learned a lot about the equipment needed to increase the voltage from our 480 to networks of 13 kVa and above – and sometimes (picture below) this equipment catches fire. Cromey noted that generator step-up transformers (GSUs) are often the single most important point of failure for site operations.
Common issues for this hardware include tank leaks, bushing failures, bushing connections, loose tap changer contacts, and core grounding / core overheating issues. And because this hardware has such long lead times to build these units, many owners – Southern Power included – choose to purchase aftermarket units.
Southern Power has a GSU strategy that encompasses all of its renewable energy fleet. Many of their facilities have spare GSUs located onsite and ready to deploy if needed. For 13 of Southern Power’s sites, we are looking to acquire a resilience reserve that would be stationed in Memphis. This reserve would have several configurations, which would allow it to serve 13 of their renewable sites. This resilient spare could be deployed at any of these 13 sites and up and running in a week, instead of the typical 12-18 month lead time for manufacturing a new GSU.
Not only that, but Southern Power, just as Enel imagines it with inverters, actively monitors these units to project future outages, further shrinking the system, as hardware this size wipes out entire power plants – compared to simple chains.
Of course, a lot more nuance and knowledge has been communicated than what I could write was covered by these two professionals – and that is why we attend conferences on solar energy. So if you are into solar power operation and maintenance maybe consider a visit. This author of pv magazine United States will be there.
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