Practical Lessons Learned from an Installed Grid-Edge Microgrid

This paper presents the lessons learned from an installed grid-edge microgrid within a distribution utility in rural Western Canada. A discussion on the overall operations and protection takes place to demonstrate the viability of the microgrid during both grid and islanded operations. One lesson that is discussed is setting undervoltage protection to prevent nuisance tripping when black-start capabilities are required during islanded operations. The methodology for overcoming the nuisance tripping is outlined with actual data collected from the implemented system. The use of neutral grounding resistors (NGRs) is also discussed in the context of grid mode relay desensitization. Further demonstration of how the NGR affects islanded operations using the EMTP-RV software is outlined with solutions via a bypass explained in detail. Practical implementation of the bypass is presented using modern infrastructure. Lastly, a case where the NGR bypass fails is discussed with field data to demonstrate the need for NGR considerations within islanded operations.