What is it about?
A microgrid is a type of resilient electrical power system. It's increasingly employed as part of the critical and non-critical infrastructure, such as hospitals, residential buildings, emergency systems, etc., to maintain or to increase the availability of services such infrastructure provides us. In the paper, we discussed a few protection design, stability, and control challenges associated with microgrids based on our experiences from designing and troubleshooting two real-world microgrids. We also provided the following: a detailed analysis of the observed site protection and stability challenges, supported by an extensive set of site measurements and simulations; and, the efficacy of our proposed and or implemented solutions.
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Why is it important?
The quality of services we expect from critical and non-critical infrastructure is reliant on the energy systems—including, microgrids—that power that infrastructure. Most microgrids are deployed on existing distribution utility or utility customers’ systems, with existing and or with additional equipment. And developing microgrids within existing systems to offer desired features present several unique challenges, particularly the protection and stability-related microgrid challenges, which are among the most common. Our work showed that microgrids may require faster short-circuit clearing times and faster protection systems, particularly if those microgrids are to provide a seamless transfer between their grid-tied and island operational modes. When traditional, Relay-based Protection Systems (RPSs) fall short of meeting protection speed requirements, alternative methods, such as a Utility Disturbance Detection-based Protection Scheme (UDDPS), could be used to meet the application needs. We demonstrated the efficacy of the site implemented UDDPS solution over an RPS solution via simulations. Our work also showed that several dependent or independent phenomena, such as a harmonics, voltage flicker, converter instability, etc., could occur, including simultaneously, in microgrids when those microgrids are operated as an island or are connected to weak utility grids. We found that it was important to gather as much site information or data as possible, including via onsite testing, to draw key insights, connecting various pieces of information and data, thoroughly understanding the problem, and establishing the source of that problem. We successfully replicated and studied the observed site stability phenomenon using a mathematical model of the system in a simulation environment. We also successfully showed that the simulation-based studies can assist to identify potential problems at the site before commissioning and to develop effective solutions to address those problems. We also formulated a few solutions, and demonstrated, in the paper, the efficacy of those solutions.
Perspectives
The work here is an outcome of a tremendous collaborative work, for a period over two years, between the co-authors of this paper and other internal and external colleagues and customers, bringing in different perspectives and expertise from their respective fields to gather useful insights and recommendations to improve the quality of our analysis, insights, and solutions we presented in the paper. The paper is a testament to this collaboration and hard work. Thank you! I sincerely hope that the work presented in the paper adds to designing, engineering, and operating resilient microgrids.
Dr. Sarat Chandra Vegunta
Siemens Industry, Inc.
Read the Original
This page is a summary of: Impact of Site Conditions and Requirements on Microgrid Design, Control, and Performance, IEEE Transactions on Smart Grid, January 2022, Institute of Electrical & Electronics Engineers (IEEE),
DOI: 10.1109/tsg.2022.3157769.
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