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.

This paper presents an investigation into overvoltage issues triggered by distributed energy resources (DERs) tripping. The expected voltages are presented from initial planning criteria based on slack bus modelling of the transmission substation. Results demonstrate that transmission voltage fluctuations are exacerbated at weak substation distribution buses. Results are determined through actual system measurements and simulation in the CYME software.

This paper presents a protection and operating scheme integrated into an installed grid-edge microgrid in rural Western Canada. The scheme employs a centralized controller with relays utilizing traditional overcurrent elements in conjunction with voltage and frequency components to yield efficient protection and operation of the microgrid in both grid and islanded modes. The relays are independent and use a single group of settings removing the need to change based on operating topology. The proposed elements are utilized to handle the drastic differences in fault characteristics when transitioning between grid and islanded modes. The proposed scheme is tested in a laboratory environment with an Omicron test set and SEL relays which confirm its efficacy in the context of this microgrid’s application.

This paper presents the steps and considerations used for a microgrid that is operating in a distribution utility. The case study discusses five major considerations namely system components, system characteristics, grid forming and return-to-grid transitions, operations, and protection. Within these considerations, questions and criteria are discussed to allow for successful implementation of the microgrid. Additionally, a list of considerations is compiled and presented for others to implement microgrids within their own networks.

This paper presents effective grounding criteria for high penetration inverter-based resources (IBRs) in distribution networks. It demonstrates that traditional methods of employing supplemental grounding exclusively does not prevent excessive ground fault overvoltages (GFOV) where adoption levels of IBRs exceed a distribution feeder minimum load. Definitions and requirements are presented for quantifying and mitigating IBR-caused GFOV such that the distribution utility is protected. The requirements are tested using a real, albeit generic case study within the EMTP-RV environment to demonstrate their efficacy.