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This is the text version for the video Optimizing Voltage Control for Large-Scale Solar.

Murali Baggu, Ph.D.: Duke Energy has a lot of substation size PV inverters, which can have very high impact on the voltage levels and power transfer and reverse power flow within the distribution grid. So they have to actively monitor these, control these particular PV inverters.

This particular project paved the way to really see how we can control this inverter at a scale which will matters, so that they can apply this to all the different inverters within their territory.

Bryan Palmintier, Ph.D.: There's a number of unique things about this research. In this context, we used the actual distribution management system software in the loop during simulations, both for long term studies, as well as in some hardware in the loop studies, where we had actual devices interacting with
this. So this is a fairly unique example of using production operation software in the process of doing an analysis for planning.

Murali: So GE Grid Solutions ADMS offers a comprehensive solution for the utilities to really monitor what's happening in their system, and in this case actually their algorithm is also controlling PV inverters along with the legacy distribution assets like cadbanks and voltage regulators.

Bryan: There are a number of innovative aspects to this project. We developed a bootstrapping statistical technique to allow us to look at full years' worth of results, using only four year representative days.

Another innovation was in the use of a co-simulation technique to enable multiple different tools to interact with each other. This included the DMS for power flow, as well some models we built of the inverters, and later on, with the hardware itself.

We also looked at the use of the PV inverter as a controllable asset for managing the system-wide voltage, and found that it was effective, but had some room for improvement that we were able to provide suggestions to GE for future version of their product.

We wanted to make sure that what we were simulating matched reality.

So we took advantage of the unique capabilities of ESIF to have hardware, a real actual advanced inverter, in the lab, interacting in real time with the distribution management system, to validate that we are capturing the advanced inverter properly in the models we use for the longer simulations.

Murali: I think it's a very good match of three entities, Duke providing the real feeder data, and GE Grid Solutions providing the advanced distribution managed systems solution as a package, and we really – creating the right environment as a utility to evaluate the algorithm.

Bryan: The research showed that while advanced inverters can do a lot to help with managing voltage, that use of a distribution management system in conjunction with them can really help improve the voltage management within the distribution system.

The economic savings system-wide could easily be in the millions of dollars.

What we saw on an individual feeder was that these advanced controls can cause considerable reduction in the need to replace equipment, as well as in reducing the losses on the system.

I think the most exciting thing about this project is that we've shown that advanced inverters, along with other technologies, can really improve solar beyond either one of them alone.