Page 58 - Energize October 2022

TECHNICAL

Considerations for microgrids with

dissimilar energy sources

As more renewable energy sources and battery storage units are specified and incorporated into
power systems, consultant specifying engineers are faced with many challenges which could
impact the overall design and performance of these solutions.

by Hassan Obeid and Jaimie Hamilton-Antonson, Cummins

his article outlines and addresses diesel or natural gas generator sets, wind turbines, solar panels, fuel cells and energy
some of these challenges to aid storage.
Tin the system design, explains Microgrids may even incorporate combined heat and power (CHP) to address both
some common components found in electrical and thermal energy needs of its users. Through on-site generation with a
microgrids, and discusses the value microgrid, consumers of electricity can achieve their goals of increased resiliency,
of an advanced microgrid controller lower energy costs, greater independence, and reduced environmental impact by
for system operation. The traditional becoming producer-consumers or “prosumers” of energy.
top-down flow of electricity from large,
centralised power plants, through Challenges when evaluating a microgrid application and
transmission and distribution lines to incorporating dissimilar energy sources
a power meter, has been experiencing Some of the considerations related to microgrid projects are as follows:
disruptive forces over the past two • Finding an optimal economic and environmental solution with the best return on
decades due to deregulation of energy investment (ROI)
markets, de-carbonisation, technology • Identifying the right combination of traditional, renewable, and storage assets to
advances, availability and cost decline, meet the operational and load demands
higher customer expectations, and • Integrating the various generating, storage, controls and electrical distribution
increased penetration of renewable assets with simplicity
technologies. • Synchronising and paralleling dissimilar energy sources
Today, power consumers can • Complying with grid code requirements for interconnection
become power producers as roof-top • Ensuring continuous resiliency and uptime
solar, behind-the-meter generators • Handling changes in resource availability such as cloud cover, changes in wind
and battery energy storage systems speed and seasonal variation
become more economical and • Ensuring both electrical and thermal loads are satisfied consistently and securely
ubiquitous. Additionally, concerns • Managing assets to ensure best efficiency and longest lifecycle
about the reliability of the traditional • Reducing utility demand charges
utility electricity due to its aging • Generating revenue through demand response programs, behind the meter
infrastructure, extreme weather events applications and net metering
and more sensitive loads have led to • Designing for future load expansion needs
wider adoption of microgrids.
Where to start?
What is a microgrid? When beginning to evaluate a microgrid project it is important to:
A microgrid is a local energy grid with • Identify the goals of the project and customer in undertaking a microgrid project.
control capability. Microgrids can be • Engage the local utility to understand interconnection requirements in the case of a
disconnected from the traditional grid utility connected, and evaluate if the cost and complexity of interconnection can be
and operate autonomously. Some avoided through a system architecture such as “open transition” to and from utility.
microgrids may be entirely off-grid • Conduct a feasibility study and stability analysis.
and be the prime power source for the
end-users it serves. These microgrids A feasibility study would evaluate the needs and constraints of the specific site and
may incorporate a variety of traditional customer to identify a wide range of design options. It would look at assets such as
and renewable power sources such as synchronous generator sets, battery energy storage, solar, wind and fuel cells, etc., to

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