A Western engineering professor has developed a way to ease stresses on the electric power system, with a smart inverter that allows solar farms to be put to work even at night.
Even better, the technology has been proven to improve the power system’s stability and flexibility – preventing blackouts and eliminating the need for extra transmission lines to handle new renewable power generation – at less than one-tenth the cost of conventional solutions.
And when we’re talking about system upgrades that would ordinarily cost $50 million but instead are $5 million, that’s near-revolutionary.
Now, professor Rajiv Varma has written a book that illustrates why and how others can do the same.
The essence of Varma’s invention – for which he has 23 international patents and another nine patents pending – is an improvement on large regulator devices, called static synchronous compensators (STATCOMs), that are placed on transmission systems to control voltages along the lines. Used over the past three decades, these STATCOMs are a cost-effective alternative to building additional transmission lines to manage increasing power generation and loads.
But Varma’s smart solar PV device – called PV-STATCOM – is a multi-purpose tool, compared to the conventional single-function device.
“During the daytime, the entire capacity of the PV-STATCOM is used as an inverter to feed solar power into the grid, which turns on our lights and powers our homes,” Varma explained.
“But when it’s night or the sun is not up, we use the whole capacity of the PV-STATCOM to provide those other smart inverter functions, stabilizing the grid and controlling voltage surges in the span of 50 milliseconds, less than even the time that we take to blink an eyelid.”
During daytime, if a disturbance occurs in the power system, the PV-STATCOM reduces solar power output briefly for just a minute and provides system stabilization. “The solar farm only feels it as the equivalent of a tiny cloud passed over it, but in the meantime the PV-STATCOM has stabilized the grid.”
If the technical specifications are a bit dense to understand, the benefits are much clearer: it can save the power industry and taxpayers millions of dollars.
A new transmission line from London, Ont., to Toronto, for example, would cost roughly $700 million. A conventional STATCOM, instead, provides the same transmission capability for about $50 million. Varma’s PV-STATCOM, harnessing the power of an existing solar farm to use as a smart inverter and voltage regulator, would cost just $5 million.
To use a real-world example, Varma’s team installed a PV-STATCOM on an existing 10- kilowatt solar farm operated by Bluewater Power, Sarnia. During the day, the solar farm feeds energy to the grid. At night, the PV-STATCOM – about the size of two microwave ovens stacked on each other – is used to stabilize critical motors such as ones used in the petrochemical industry where transmission reliability is essential because even a momentary power surge or outage could cost millions of dollars.
Piggybacking on the existing solar farm, Varma’s system costs one-tenth the cost of a conventional STATCOM for providing the same power grid stabilization services.
“So it has a potential to bring new revenues for the solar farms; utilities are happy because their systems are more efficient, and industry is happy because they can count on reliable power most cost-effectively.”
Varma is a Fellow of the Canadian Academy of Engineering (FCAE). He is the second Canadian recipient in 22 years of the IEEE PES Nari Hingorani FACTS Award, the most prestigious award in Flexible AC Transmission System (FACTS) technology – which he got for development of PV-STATCOM. He has also received 13 teaching excellence awards at Western.
The first part of Varma’s new book, Smart Solar PV Inverters with Advanced Grid Support Functionalities, published by Wiley /IEEE Press, examines developments in smart inverter technology around the world since they were first developed: how they can transform power systems, connect more renewables, reduce line losses, save energy and lower the overall cost of electricity for consumers.
The second part of the book illustrates how the even newer PV-STATCOM technology can super-size the benefits of ordinary STATCOMS, providing several grid support functions at a fraction of the cost.
It’s distilling a whole lifetime of learning and innovation into this book, which Varma hopes will be useful to electrical engineers, systems planners and operators, inverter manufacturers, students and academics.
“In 2009, when we said you can use a solar farm in the night, people in the industry said, ‘What? There’s no sun. Are you using moonlight to operate the solar farms?’ So I had to explain how we’re transforming the solar inverter to provide new functions at night. It was out-of-the-box thinking, innovative thinking, that a system which is ‘sleeping’ can be awakened to provide all these functionalities at a fraction of the cost.”
