Components of Microgrids

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Microgrids are technology marvels. Check out the different components that come together under a microgrid.

Utility grids and microgrids have a lot in common. Both serve the same function—to provide electrical power to consumers. Both are subject to the same constraints—ensuring that electrical generation and electric load are equal at all times. Their components, however, are different. 

Microgrids are at a much smaller scale than utility grids and as a result include components that are accordingly scaled down. 

Here are the main components of a microgrid:

Electricity generation resources within microgrids

The beating heart of a microgrid consists of a set of electricity generation resources. Typical generation resources found in microgrids include diesel and/or natural gas generators, solar arrays and wind turbines.

The most basic microgrids are usually built around one or more diesel generators. When natural gas is available, gas generators are also among the options available. Older island microgrids, for example, are based on a small power plant consisting of a few diesel engines coupled to alternators. Generators are the default choice to power a microgrid because they can cover a wide range of loads and because they can be used as backup power. They start quickly, are responsive to changes in load, and can operate on a variety of fuels. 

Fuel cell technology is emerging as a valid option to provide on-demand power on microgrids. Fuel cells can run on natural gas, hydrogen and other less common fuels. Although their cost remains too high to be widely used, hydrogen fuel cells are seen as a potential source of small-scale CO2-free electricity.

Typical components of an island microgrid
Click the image to take a closer look at microgrid components

Intermittent energy resources within microgrids

The cost of solar panels has become so low that, in some regions, their installation on homes and businesses is a no-brainer. University campuses, industrial facilities and others equipped with a microgrid can install solar arrays in large numbers, thus achieving significant savings on their energy bills. In fact, many build a microgrid specifically to be able to better integrate and take advantage of their solar resources. 

Energy storage within microgrids

Many homeowners sometimes choose to supplement their home photovoltaic installation with a battery pack. Likewise, many microgrid owners incorporate battery energy storage in their system. With the price of lithium-ion batteries at an all-time low, the benefits of adding an energy storage resource often justify the additional cost. 

For one, battery energy storage systems provide a service known as “time-shifting”. Time-shifting batteries collect extra electricity from an oversized solar system during the day, and then discharge the battery after the sun has set to meet overnight load demands. Similarly, batteries can be discharged at times when the solar array output does not match the load requirements such as short periods of peak demand. This allows the owner to maximize the use of intermittent resources.

Another benefit of battery systems is their ability to instantly respond to changes in electricity demand on the microgrid. Having a battery serve as standby capacity is often much more cost-effective than idling an extra generator 24/7 in case demand increases unexpectedly. Think of energy storage as the fat on the microgrid where energy is stored.

Load management within microgrids

Some microgrid owners have the option to actively manage electricity demand in the same way that they manage electricity generation. 

By default, when a large electric machine starts up somewhere on the microgrid, the generators supplying the microgrid need to quickly ramp up to meet the additional demand. Microgrids that actively manage demand have another option. They can decrease demand somewhere else on the microgrid, for example by switching off a building’s AC temporarily. The result is that demand and generation are again balanced out without increasing generation.

Control and communications within microgrids

Microgrids need a brain and a nervous system to operate safely and effectively, thus needing to possess sophisticated microgrid control systems

Wide-area utility grids serve millions of consumers and have a considerable amount of inertia, limiting the potential for fast, uncontrolled changes. Microgrids, in contrast, include fewer loads and resources and are more sensitive to variations in load and generation. Starting up several large electrical machines without the assurance that an equivalent amount of generation is available is a sure way to crash the microgrid. 

A microgrid’s control system typically includes multiple controllers and sensors distributed over its territory. A Supervisory Control and Data Acquisition (SCADA) system is also required to collect data and distribute instructions. 

If the SCADA system is the nervous system of the microgrid, then the energy management software is the brain; that software can be highly sophisticated. Artificial Intelligence (AI) and machine-learning features allow modern energy management software to learn to better anticipate load from the consumers on the microgrid and generation from renewable assets, to optimize the system to run in the most cost-effective way. Maximizing the use of renewable resources, minimizing fossil fuel costs and maintaining the reliability of the equipment and the microgrid, all while dispatching the load, is all taken care of by the energy management software, within the parameters specified by the owner of the microgrid.

Switchgears, inverters and other equipment

Finally, microgrids include other critical components such as electrical cables, circuit breakers, transformers and more. These components are the bones, muscles and blood vessels of a microgrid. They connect generation resources to consumers, and allow the microgrid’s control system to effect changes to the state of the microgrid.

Automatic transfer switches, for instance, isolate different generation assets to ensure that, for example, the AC inverter associated with a solar array does not feed electricity to a diesel generator. Inverters convert the DC power supplied by batteries or by solar panels to AC power that is adequately synchronized to other AC resources on the microgrid. 

Interested in more on microgrids? You might also like: 

Aytek Yuksel - Cummins Inc

Aytek Yuksel

Aytek Yuksel is the Content Marketing Leader for Cummins Inc., with a focus on Power Systems markets. Aytek joined the Company in 2008. Since then, he has worked in several marketing roles and now brings you the learnings from our key markets ranging from industrial to residential markets. Aytek lives in Minneapolis, Minnesota with his wife and two kids.

Cummins Custompaks are being used for water management as Thailand struggles with its water crisis

CustomPak on site

Water crisis

Sixty Cummins Inc. CustomPaks are in service in Thailand as part of a critical water management plan aimed at easing the country’s water crisis – a crisis that has caused enormous economic and social damage and stirred conflict among communities.

Over the past several decades, Thailand has continually faced water problems caused by severe drought. Water reserves in dams and reservoirs are insufficient while water resources are often contaminated with toxins caused by urban communities and the industrial and agricultural sectors.

Severe flooding is a threat, too, at a time when the realities of climate change are hanging over the country.

As a result, the allocation of precious water resources, which must be shared among various stakeholders including new and existing industry, large and small agriculture, and cities and villages has become a flashpoint.

Kittithanapat Engineering Co. (KTP), has been involved in the water management system since 1996, working closely with authorities such as the Royal Irrigation Department, Department of Water Resources, Bangkok Metropolitan Authority and others.

CustomPaks on site

600 hp CustomPaks

To help KTP meet its often urgent requirements, Cummins DKSH (Thailand) has recently supplied 60 Australian-built CustomPaks – 45 powered by Cummins’ X15 engine rated at 600 hp, and 15 powered by the QSL9 rated at 325 hp. These fully self-contained powerpacks are emissions certified to Tier 3.

The CustomPaks are coupled to hydraulically-driven, large-volume submersible water pumps sourced by KTP from US company Moving Water Industries (MWI); KTP is the exclusive distributor in Thailand for these MWI Hydroflo pumps.

Prior to Cummins’ involvement, KTP was using another diesel engine brand but service support wasn’t up to the standard required.

Long-serving KTP engineer Kittisak Thanasoot says Cummins DKSH’s reputation for technical and aftersales support along with the reliability of the Cummins product were a key reason behind KTP’s decision to specify the CustomPaks for the Royal Irrigation Department.

The ability of Cummins DKSH to respond to short delivery times was also important.

“Supplying large quantities of high horsepower diesel engines for emergency situations such as flash flooding can be a challenge for KTP,” says Kittisak Thanasoot.

“Responding to the needs of the government agencies to manage such problems in a timely manner and with least impact on communities, KTP has found the answer in our partnership with Cummins DKSH.”

Power, pride and passion

Parked semi truck

The switch back to Cummins power has been beneficial for iconic New Zealand company Uhlenberg Haulage. It's all about whole-of-life costs.

Uhlenberg Haulage is closing in on 60 years in business, having been founded in 1966 by Mike and Carol Uhlenberg.

Based in Eltham, Taranaki, in New Zealand’s North Island, the operation is today owned and operated by their sons Chris, Daryl and Tony Uhlenberg.

Describing the Uhlenbergs as “old school family truckies”, Daryl talks about the company’s time-honored journey with a definite tone of pride, especially the work of his parents in laying the foundations for what is today an iconic fleet in its own right.

Cummins Inc. made its debut in the Uhlenberg fleet in 1971 with an NH250 powering a second-hand Kenworth K923 used in logging. A second Kenworth, a new W924 with a Cummins NTC335, followed soon after hauling an LPG tanker.

The Uhlenberg operation today comprises 40 prime movers and a variety of trailing gear to cater for the myriad of a jobs the fleet is involved in.

A number of Peterbilts feature in the fleet although Kenworth is now the brand of choice with six new units to be delivered over the next 12 months to cater for business growth.

Cummins’ X15 Euro 5 engine rated at 550 or 600 hp is the preferred power specification, with 18 red engines currently in the fleet.

Uhlenberg family in front of truck

Whole-of-life support

“The switch to Cummins has been a very good experience for us. We have nothing but praise for the Cummins organization,” says Daryl.

“The whole-of-life picture is the key thing for us and we’ve got that nailed with the support we get from Cummins – parts availability, scheduled maintenance, life expectancy and in-frame rebuilds.

“So the red engines turn up, we run them to life, which is 900,000 to 1.2 million kilometers, and then Cummins does an in-frame overhaul in a timely manner. If there’s an issue, parts and support are close by.

“The support we get from Cummins Palmerston North is fantastic, second to none.”

Daryl recently looked under a Kenworth that was in the workshop for a service and was surprised to see no oil leaking from the one-million-kilometer X15. “I remember when I was a fitter we had to wear a raincoat when working under a truck,” he jokes.

Fuel agnostic

Acknowledging that the push to decarbonize is now “very real”, Daryl likes the idea of Cummins’ fuel agnostic concept where one base internal combustion engine, optimized to run on diesel, can also be customized to run on ultra-low and zero-carbon fuels like renewable natural gas and hydrogen.

“My father was a pioneer of linehaul trucking in New Zealand and he always embraced new technology. He was never scared of it,” he says.

“I tend to be a little more cautious but I can see where a 500 hp natural gas or hydrogen engine would work for us in short haul applications,” he admits. “We’re certainly willing to look closely at these alternative fuel technologies when suitable infrastructure is in place.”

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