How to build a microgrid

Photo credit: S&C Electric.

Microgrids are becoming more and more prevalent today, representing a modern approach to solving a variety of energy supply challenges. Their unique nature, however, can still trip up even the most advanced engineers and utility staff. Before starting to design a system, it is important to understand the process of bringing about a microgrid from initial concept to real-world operations. Most important is understanding how to actually build it.

1. Feasibility assessment

The first step is to conduct a feasibility assessment. This will help uncover a system’s potential benefits, challenges and life cycle, with a unique site in mind. Financial, resiliency and sustainability opportunities will all vary from place to place.

It can be easy to overlook details at the beginning of the process, but missed details often result in increased costs and project delays. The following are some of the basic issues to address during the feasibility assessment:

• Have you mapped the microgrid’s functions back to the problems you want solved?
• Which of your electrical loads are the most important?
• How fast must the microgrid come online when grid power fails?
• How long must it remain operational in ‘islanded’ mode?

Key to all of these considerations will be the power supply:

• Which types of power generation will you include in the microgrid?
• Will you ‘own’ new on-site power generation assets or will you sign a lease or service agreement with another party?
• How much power will be needed from the microgrid?
• How long will independent power generation be needed?
• Is fuel available and does it need on-site storage?

Often, it is easiest to analyze where generation assets already exist and build around them:

• What electrical infrastructure and equipment that can support a new microgrid are already in place at the site?
• How do existing and future planned energy assets line up with existing and future loads?
• How and when can power flow within the microgrid?

2. Preliminary system design

The next step (although it often happens in conjunction with the feasibility assessment) is to complete a 30% system design. This involves laying out the basic types and sizes of technologies involved, their intended locations, the methods for interconnecting them within a microgrid and a plan for working with the local utility. The goal here is to help set the course for future detailed design considerations.

With regard to location, one of the key considerations is determining the best place to build:

• Do the topology and site features match up with the type of power generation likely to be used?
• What are the potential local environmental concerns about the microgrid, such as visibility, noise and/or emissions?
• How might the microgrid affect the community and utility infrastructure?
• How will buildings be connected to the energy source?
• How many switching procedures will be required to start or stop the power flow at different locations within the microgrid? (Note: The fewer switching procedures, the better.)
• How can the microgrid leverage the site’s existing data communications infrastructure?

3. Financial planning

Before beginning the full design process, it is also crucial to conduct financial planning and develop a cost estimate for the project. These are critical to a system’s feasibility and can illuminate opportunities for third-party financing. It is important to lay out all budgeting guidelines, so as to accommodate such assistance and equipment purchasing.

The following are some questions to consider when evaluating financing options for the project:

• How will the microgrid be paid for, including capital and operations and maintenance (O&M) costs?
• Have all necessary regulatory approvals been secured?
• Do you have buy-in from executives, customers and other stakeholders?
• Who will be working on this project and will it need support from specialized third parties?
• Will long-term maintenance of the microgrid be managed in-house or outsourced?

4. Integrator selection

Another critical step before completing the full design of an advanced microgrid is the selection of an experienced integrator. Their expertise, based on a history of successfully developing other microgrid projects, can streamline the process from design through commissioning, to avoid foreseeable challenges and delays.

5. Full design

Once these steps have been taken and the logistics of the system have been determined, it is time to carry out the full design, moving forward from 30% to complete blueprints and documentation, including a utility interconnection agreement. A high level of expertise will be needed at this stage. The integrator assisting with the project should be very familiar with electrical distribution equipment, distributed energy resources and control software.

6. Equipment procurement and construction

After the design is agreed upon among the engineers, the utility staff and the integrator, the next steps are to procure the necessary equipment and begin construction.

When procuring equipment, it is important to consider not just the initial costs of the components, but also their overall life-cycle operating costs. Also, many of the larger components needed for a microgrid, including energy storage systems and switchgear, will involve long manufacturing lead times. Construction timelines should be planned with procurement timelines in mind.

7. Commissioning

The completion of construction does not represent the completion of a microgrid project. Rather, before it can be fully operational, it must undergo system commissioning.

This phase involves thorough factory and site acceptance testing to ensure all of the components and connections perform as a coherent system. This is also the time to educate relevant employees about the functions and features of the system and its operation.

8. Monitoring and maintenance

Even after a microgrid has been successfully commissioned, it will still require ongoing attention.

Microgrids are complex systems that will need more than just regular maintenance to keep them operating at optimal performance levels. Using a control system specifically designed for microgrids will help, as will having a well-trained and knowledgeable service staff. Some integrators offer long-term remote monitoring and diagnostics, which can provide a cost-effective means for maintaining peace of mind over the long term.

Erik Svanholm is vice-president (VP) of non-wires alternatives for S&C Electric. For more information, including microgrid development guidebooks, visit www.sandc.com/microgrids.