How to Evaluate Ground Fault Trips in a Microgrid using ETAP software

There is much we can achieve in ETAP modeling the Microgrid. Low flow studies, short circuit studies, minimum versus peak load studies, and switching scenarios can all be modeled and analyzed in ETAP. They must be investigated to ensure the system functions correctly and operates safely.
By Jesse Hoffman, Engineering Manager at Energy Systems Group

In this technical presentation, we learn about problems associated with adding distributed generation sources to existing power distribution systems. If not properly designed, implementing islanding microgrid capability introduces protection and control challenges. Each new generator may present a new source ground fault current to the system, which can result in unanticipated breaker operation. Energy Systems Group was using ETAP to model the system and check the coordination of local and remote breakers, which can reduce downtime and troubleshooting.

The Energy Systems Group, LLC is headquartered in Newburgh, Indiana, and maintains a separate headquarters for the federal team in Eagan, Minnesota. Their offices are located throughout the U.S. and help companies achieve their energy efficiency, resiliency, and sustainability goals.

Location: Newburgh, Indiana, United States

Year: 2022

Selection of the current transformer in medium voltage

Challenges

  • Identifying the impact of the design errors of the Microgrid grounding configuration. What happens during ground faults in a microgrid system, and what will happen with grounding in islanded mode? The main challenge was to check the quality of the existing design for one of the customers and propose corrections.
  • Taking off the blinders. Understanding how the microgrid operates normally with the Utility system connected and how it works in an isolated way. Engineers typically check the generation process. It's a fault. In fact, the utility system and its safety are essential.
  • Considering power flow, fault current flow, peak power, switching requirements, and all required analyses and calculations. Every electrical design case is different and should be checked before starting the build process.
  • Modeling the variations of the electrical distributed system and utility grid, with different grounding models, different types of transformers, and options for connection.
  • Considering the impact of generators on harmonic current. Modeling appropriate transient systems and overcurrent protection.

Which solutions did they choose?

Selected applications

They chose the ETAP Base Module with ETAP StarZ and System Grounding and Earthing in context with the Microgrid to analyze variations of grounding and variations of transformers and to find the correct design of the microgrid connected to the utility grid.

The ETAP solution guaranteed compatibility with actual standards for electrical distributed systems. 

Why do they use ETAP?

Main Customer Benefits

  • Easy modeling of the required variations of the electrical grid system saves time by adding accurate electrical data from the field. All symbols have built-in electrical parameters. In ETAP, the process starts from design and continues through the analysis to the operating stage. It is all in one model and one software. Another software is not required until the grid reaches its end of life.  
  • The flexible ETAP digital twin model includes all required electrical studies and has a built-in actual calculation standard, so engineers do not have to look for paper documentation.
  • Compared to the other software, ETAP analyses are understood by users. The vital user benefit is the intuitive evaluation of the studies and clear visualization with warnings.
  • If the design problem exists, ETAP suggests how an engineer can solve it (e.g., changing the transformer type or grounding system).
  • The main direct benefits were a conclusion that transformer winding configurations are critical, especially when connecting generators, and should be changed from Y/Y to Y/∆ configuration. The design was changed, and an appropriate type of transformer was used. The system became safe.

What do they think about ETAP?

Opinions

This engineer was more familiar with backup power generation on the low-voltage side and then grid-parallel operation, but mainly on the low-voltage side. One thing we can do with ETAP is to help visualize and train people on what to watch out for. We can design systems like this in ETAP.
By Jesse Hoffman, Engineering Manager at Energy Systems Group

As long as we're doing all these studies properly, rapid ETAP checks can prevent major cost and schedule impacts on microgrid projects.
By Jesse Hoffman, Engineering Manager at Energy Systems Group



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Using ETAP to Evaluate Ground Fault Trips in a Microgrid

Adding distributed generation sources to existing power distribution systems and the implementation of islanding microgrid capability introduce protection and control challenges if not properly designed. Each new generator may present a new source ground fault current to the system, which can result in unanticipated breaker operation. Energy Systems Group, was using ETAP to model the system and check coordination of local and remote breakers can reduce downtime and troubleshooting.


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