An Introduction to Microgrid Energy Management Systems

With the growing number of industries and businesses, access to reliable and cost-effective power is critical. This leads to demand for small-scale power supply networks to cater to the communities. The microgrid thus formed serves as a connection between the power generation facility and the utility grid [1]. It enables resilience, reliability, energy efficiency, environmental benefits, and economic gains. This promises uninterrupted power, thus prevents outages, and manages energy loads of multiple generation systems along with storage systems. The management aspect of the microgrid is handled through dedicated software and control systems. Read on to learn more about what a microgrid is, how it works, and its pros and cons.

Microgrids are a growing segment of the energy industry and represent a paradigm shift from remote central power plants to more localized distributed generation [2]. The  microgrid concept has been around for several years, but it has gained significant traction in recent years as many projects are put into production, turning the concept into reality. If we observe closely, we realize that the early power systems developed by Thomas Edison and Nikola Tesla were all essentially microgrids. They are known to be revolutionary as they act as new drivers supporting the expansion of electrification while reducing the carbon footprint and enabling new technologies to support clean energy endeavors.

The microgrid is a local energy system capable of producing and distributing energy and is composed of different types of assets, also known as distributed energy resources (DERs), as illustrated in Figure 1. It can also be termed as a miniature power grid system that manages DERs, including both renewable and non-renewable sources of energy. It can be connected to the grid-like in healthcare facilities where continuous power is inevitable or be run entirely off the grid as it is self-sustaining in nature, like in remote sites that require tremendous amounts of energy. 

Figure 1: Illustration of a microgrid [4]

The process of building a microgrid can be described as that of a Paladin lifecycle [3]. It involves the initial feasibility study of the site, the possible design, and the modeling of it. It is followed by the power study, including model-based studies, forecasting, and optimization. The next stage involves system design and management, including analysis of interconnection, implementation, and real-time simulations. The final step involves real-time control and optimization of all the power components.

 

Components of a Microgrid

The U.S. Department of Energy (DOE) defines a microgrid as "A group of interconnected loads and distributed energy resources within clearly defined electrical boundaries that acts as a single controllable entity with respect to the grid. A microgrid can connect and disconnect from the grid to enable it to operate in both grid and island modes" [5]. A microgrid generally comprises renewable or fossil-fueled generators, loads, energy storage systems, circuit breakers, and control equipment, as illustrated in Figure 2. 

The most commonly employed assets to generate power are photovoltaics (PV), wind turbines, and power generators. The other elements critical in terms of the functionality of a microgrid include storage systems, smart controls, and software that facilitates interconnection. All of these components need to work well together to ensure a seamless customer experience while adhering to standard regulatory requirements.

Figure 2: Components of a microgrid [6]

Advantages of Microgrids

The formation of microgrids assures efficient and low-cost clean energy along with reducing grid congestion and peak loads. It helps improve the stability of the grid while enhancing the reliability and resilience of the critical infrastructure. It also helps in reducing the carbon footprint and line losses while promoting the use of renewable energy sources. 

Microgrids offer several financial benefits, including tax breaks, discounts and avoid peak pricing burden. It is also diversified and produces energy from multiple sources like wind, solar, and fuel cells, adding several levels of security [3]. They come in handy as they are smaller and can be installed quickly than traditional power plants. Further, microgrids can integrate with the grid along with other smart grid technologies with ease.

 

Disadvantages of Microgrids

The main disadvantage of a microgrid is the resynchronization with the main grid.

There is also a need for ample storage, which again demands an additional cost, maintenance, and space for installation. There is some resistance from the utilities to implement microgrid technologies. There are also regulatory issues that might be difficult to comply with, and it is difficult for laws to catch up with building technology. 

 

Key references:

• Microgrid - basics, structure, advantages, disadvantages - Electrical - Industrial Automation, PLC Programming, scada & Pid Control System
• Features and Benefits - Microgrids
• Power Analytics, Microgrid Basics, Part 1: The Need for a Feasibility Study.
• The Pros and Cons of Microgrids
• Microgrid Fundamentals | What is and Role Generators Play w/ Video & Graphics!
• Microgrid-graphic - Midwest