XFMR-Sync Controller Solves
Transformer In-Rush Current Issues
Charlotte, NC – Transformer in-rush current is a new hurdle for solar projects facing Duke Energy’s increasingly stringent interconnection audit requirements. For many engineers and construction companies, this is a completely unknown risk, and they are often unprepared to address the issue. In the few seconds following a grid outage event, unacceptable levels of in-rush current can occur when the utility grid is turned back on and large power transformers energize (or magnetize). The electrical load created by the transformers energizing creates a brief but sudden demand on the grid and can be measured by the utility’s metering equipment. Only recently, in-rush current has been identified as an audit requirement for new solar farms connecting to utility grids in the southeastern United States.
It’s risky business to order transformers and finalize the medium voltage plans before the utility’s full advanced study process is completed. Brad Micallef, managing director and co-founder of Solar Operations Solutions, LLC (Solar-Ops), witnessed this all too often in his role providing consultation and commissioning services to solar developers and EPCs in North Carolina. In late 2017, his customer, Wadesboro Solar, LLC, was informed that their solar farm’s theoretical transformer in-rush current exceeded operational tolerances established by the utility. After several years of planning and investment, the project was suddenly at risk.
“We were already ordering equipment and planning to start construction when we found out,” Adam Foodman, COO of O2 emc, LLC and developer for Wadesboro Solar explained. “The existing options to address ‘in-rush’ had a long lead-time and were a very unwelcome capital expense we had not planned for,” he said. “Missing our end-of-year commercial operations date was not an option and we turned to Solar-Ops for an affordable solution.”
Solar-Ops recognized that this technical hurdle was new, and that commonly used equipment was both in short supply and not appropriate for the challenge.
“We actually started with a set of simple electro-mechanical control relays to test our initial concepts, then quickly realized that the actual technical requirement for precise timing and audit processes with no power on site was deceptively complicated,” said Micallef. “In our simulations of the audit process, when there is no power on site, and often the local network is not even operating yet, the actual solution had to be very simple, reliable, and repeatable. That’s how the XFMR-Sync Controller was born.”
“From the beginning, we intended the XFMR-Sync Controller to be a standard product offering that the utility’s audit team would recognize, understand, and sufficiently document as a ‘trusted solution.’ It’s currently in use on several of our client’s projects as well as projects we manage ourselves,” explained Micallef. “The XFMR-Sync Controller is completely self-contained and may be used either as a stand-alone automated control solution or connected to the client’s DAS or SCADA for monitoring and control."
Many developers and engineers incorrectly assume the transformer in-rush requirement can be addressed by the existing inverters or through a simple timing arrangement using reclosers. These approaches do not fully take into account the source of the in-rush current, the custom programming costs, the test conditions, and the need for fail-safe operation on loss of power to the site. The XFMR-Sync Controller is a turnkey solution that fully addresses all of these requirements.
XFMR-Sync Controller Benefits:
The XFMR-Sync Controller is one of several products that Solar-Ops is developing and marketing under its new myPV™ product line. Like the XFMR-Sync Controller, all myPV products are created to satisfy the industry’s expectations of affordability, reliability, ease of installation, and ease of use. Micallef reinforces, “We use these products in our own portfolio of projects. We want products that solve problems, not just components that create more work. ‘Turnkey Solutions for PV Solar’ is our motto.”