Hardware in the Loop: Addressing the Challenges of Microgrid Systems Integration

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In a new special report series brought to you by Microgrid Knowledge and Typhoon HIL, we explore how hardware in the loop (HIL) testing and model-based engineering techniques provide an effective way to address the technical challenges that can impact the cost and scheduling of microgrid projects. This first article explores the evolving nature of our electrical system.

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In the US, the centralized grid delivers electricity to around 145 million customers. This power originates in about 7,300 power plants and travels through 160,000 miles of high-voltage power lines and huge numbers of low-voltage lines to the consumers. That energy system, however, is becoming more complex with a much larger number of energy sources as well as diversifying players, roles and even service offerings.

The traditional picture of large power stations supplying power to consumers is changing into an image with more distributed and decentralized features. Micro-generation and storage are on the rise, with consumers turning into “prosumers.” Industries and even private citizens are now producing, consuming and storing energy to improve their own position; some sell energy back to their utility or via increasingly flexible exchange markets. The rising adoption of distributed energy resources (DERs), especially nature-driven wind and solar PV in place of fuel-powered generators, complicates maintenance of voltage and frequency stability and challenges established operating assumptions.

Fifty years ago, the Tennessee Valley Authority was still working to extend centrally generated power, from dams and even nuclear reactors, to American households. Today, utilities are expected to deliver abundant, reliable electricity on demand. As the 21st century plays out, people are relearning the fact that the world continuously changes, including how energy is generated and used. Energy projections are being reshaped in light of apparent climate impacts, which lead to weather related events such as fires and storms, interrupting distribution. Power systems are vulnerable to hackers attacking from anywhere in the world. The capacity to deal with these changes and uncertainty is known as resilience.

New meaning of resilience

Resilience has moved on since the industrial era; it no longer means simply reinforcing and protecting systems to maintain their integrity through any hazard, such as wind and lightning. The modern day concept of resilience describes constructive ways to respond to events and changes of any kind, anticipated or not, by sensing, responding, learning and adapting.

Resilience thinking provides motivation to find new ways to anticipate situations and have the flexibility to prepare and respond in ways that limit negative impacts, and incrementally change systems based upon newly recognized realities. It is no longer about emphasizing that all points in the electrical system have the same quality of service all of the time. Notably, resilience involves ownership of outcomes and initiative to manage them. This is one of the primary motivations for investment in DERs and microgrids: They provide the ability to anticipate, respond and adapt, consistent with local needs.

Flexible, agile energy ecosystems

Today’s microgrids employ fundamentally new technologies to create flexible and agile ecosystems. They network electrical devices and DERs in different combinations using a new generation of power electronic converters and controllers that manipulate electrical currents and voltages up to a million times per second to deliver power in the required form to the desired location at precisely the right time. Among other possibilities, microgrids can enable improved energy resilience, reductions in carbon emissions and cost savings for the energy users. According to research carried out by Navigant, spending on microgrids is projected to increase fivefold between 2018 and 2027. Spend is predicted to be on a combination of retrofits to existing infrastructure, and on brand new microgrids.

Unlike a generator in the basement of a building or a set of solar panels on the roof of a home, a microgrid acts as a management tool for a complex system of generation sources. Equipment can be turned on and off or ramped up and down to balance demands of the energy user with availability and cost associated with market patterns and changes in weather conditions. Energy storage can help manage such dynamics and enable the possibility to continue functioning when the larger distribution network fails.

Keys to this new trend are developments in power electronics, communications and digital control systems, which have unlocked the ability for rapid data collection, analysis and coordination between individual devices. Only updating existing power systems with faster, more efficient devices would result in marginal improvements in efficiency and reliability, as opposed to the ongoing transformation of the physics of networks. Just as digital communications replaced wires, switches and tubes in analog systems with bits and packets, power electronics manipulate energy in digital form, thus dramatically increasing flexibility and agility.

hardware in the loop

For more information, download the full report.

Smart by complexity

Coupled with modern computing and communication technologies, the new digital power systems continue to become smarter and more capable. On the flip side, they are unavoidably complex. Digital power controllers simultaneously implement an expanding set of different functions that may themselves interact. Combining different devices, especially from different sources, introduces even greater potential for unanticipated behaviors and failures. This presents interoperability issues for those designing and building new microgrids, and retrofitters of new components into existing microgrids.

The increasing complexity can result in microgrid projects taking longer and costing more. According to research carried out by VDC in 2017, 43% of respondents to the Software and System Development survey reported that their embedded development projects were late.

Going forward, this is likely to become more exacerbated as embedded devices like power electronics converters become more interconnected and reliant on software for system functionality than the products they replace, leading to technical obstacles. In addition, once the microgrid is up and running, there is a risk that it will not run in an optimized way. Steps to mitigate these risks do exist, through the validation and certification of microgrids.

Hardware in the loop and microgrid projects

In the coming weeks, this special report article series will explore the following topics:

  • Design and Validation of Microgrids.
  • Hardware in the Loop (HIL) — Tried and Tested.
  • HIL and Microgrids.
  • Model-Based Engineering.
  • HIL Case Studies.

Download the full report “How Hardware in the Loop Addresses Challenges of Microgrid System Integration” courtesy of Typhoon HIL to learn more.

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