Don’t let the name fool you. Microgrids are big – and getting bigger – both in the size of individual units and total U.S. capacity. In fact, Greentech Media now forecasts that U.S. microgrid capacity will reach 4.3 GW by 2020, up from an earlier estimate of 3.71 GW. Currently, there are about 160 microgrids in the U.S. with a total capacity of 1.7 MW.
“The principal driver behind this growth is resiliency – the continuing fear of massive damage and power outages from new super-storms like Sandy – but there are a number of other reasons too,” says Chris Evanich, Applications Director of Microgrids at S&C Electric Company. He cites advances in energy storage technologies, flexible control architecture that can adapt to most any system configuration, and the availability and affordability of smart technology, including cyber security, as additional reasons that microgrids are offering utilities a number of real advantages.
“One of the most critical benefits microgrids bring to utilities is the ability to control and coordinate multiple distributed energy resources,” Evanich adds. “Not only will microgrids increase the reliability and efficiency of renewable resources, but they will also ensure and enhance power quality while, critically, creating new revenue streams for utilities.”
However, with microgrid configurations and technologies constantly evolving, utilities are finding that building and operating them to realize those benefits is still a complex, and potentially risky, undertaking. “To minimize that risk you need to take a ‘macro’ – some would say holistic – approach, one that brings together people with experience in every required discipline,” says Evanich. “But that alone won’t guarantee success,” he adds. “You must also have experienced managers, people who understand how to fully integrate all of today’s most innovative hardware, software, protection systems, and services. This is absolutely key.”
S&C breaks this macro process down into three management categories that include a total of 12 items that should be on the critical path of every microgrid development project. “It’s like a puzzle with 12 pieces that have to be put together exactly right,” says Evanich. “If done correctly, a utility will have a microgrid that is not only reliable but also scalable and future-proof.”
S&C’s macro approach to microgrids:
Sources and Loads – Gensets, renewables, battery energy storage, switchgear, and loads.
Contrary to what some people believe, developing microgrids is not traditional power engineering. Not only must you have a fundamental understanding of your existing generation assets, controls, switchgear, you must be able to create a priority list of loads on the system, identifying which loads must stay on line and which can be shut down during an event. Only then can you pick the right generation and energy storage technologies for the microgrid and begin to integrate all components effectively. Note: You must also look beyond the microgrid: a) for its impact on the larger grid, and b) for opportunities to sell excess power.
Communications and Controls – Control system, network architecture, cyber security
Whether cell, radio, or fiber optic, the integrated communication system that links various resources in a microgrid will be familiar to utility engineers. But because microgrid reliability, stability, and efficiency are completely dependent on advanced software controls, cyber security is a must. “Most engineers understand that combining all these new technologies and their many subsystem increases operational risk substantially,” says Evanich, “but they may not be aware how much it also increases the risk of cyber attack – or how to provide adequate cyber security.” Knowing full well that it’s very difficult to prevent someone from getting into a system, the key is to create a multi-layered defense that will prevent intruders from doing harm once they are in. “That may seem counter-intuitive, but it’s how the Dept. of Defense measures control,” notes Evanich.
Design and Construction – Engineering design, protection, project management, construction
Microgrid design requires a firm that understands each component and its intricacies and who has the skill to bring everything together to work in harmony. “You need to have experts in each category to design the microgrid effectively, and you need complete control over the construction process to prevent delays,” says Evanich.
Case Study: Ameren’s Test Microgrid
In May 2016, S&C Electric signed a contract with Ameren to build a microgrid that: a) had paying customers on the microgrid distribution feeder that could be islanded from the grid; b) could seamlessly transfer power back and forth from the larger grid without a blink of a customer’s lights; and 3) would provide a platform to investigate the potential return on investment of 15 separate use cases. Critically, S&C developed adaptive protection and control software to help the microgrid’s multiple generation sources move into and out of “microgrid mode” without creating an outage. Separately, S&C developed a means to “black start” the microgrid after an outage without requiring a reference voltage from the utility source. The microgrid, which consisted of one 50-kW microgrid nested within a larger 1-MW microgrid, went live in December, seven months later.