**1. Introduction**

For the last couple of years, a new solution suitable to local energy distribution within existing power systems has been proposed and developed: microgrids [1].

security reasons. Also, the development of new energy sources as well as their integration within microgrids allows the supply of some isolated locations, such as islands or mountain areas,

Energy Management System Designed for the Interconnected or Islanded Operation…

http://dx.doi.org/10.5772/intechopen.74856

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Currently, a typical microgrid configuration, **Figure 1**, consists of an open architecture, including electrical, communication, command, and control components, which allow the users and energy sources interconnection. Thanks to the capability of offering higher levels for power quality and reliability, a large number of users will adopt power supply solutions based on advanced technology and power electronics in order to minimize voltage sags, interruptions

Generic microgrids consist of a number of electric generators with static converters as interface modules, electric loads (to be connected either at DC or AC by inverter modules) as well as a connection (by transformer and conversion modules) to the electric distribution grid.

For an optimal microgrid operation, energy management strategies are necessary, proving their utility by adjusting the generated power for each distributed source [5] and by considering the energy storage which currently represents a main component of the energy sector.

The special operating conditions of the power systems require new solutions in order to ensure the continuity of the power supply. Therefore, the chapter proposes and analyzes the integration of renewable energy sources (RESs) (photovoltaic panels and wind turbines) into a mixed microgrid by using the LabVIEW software. Also, the MATLAB environment was used by introducing MATLAB scripts within the developed visual instruments (VI) diagrams.

• mixed microgrid, including various energy sources, which ensures the end user's power

• option to extend the grid infrastructure without achieving any changes in the existing

• option to store the generated power in order to establish the energy security and autonomy

The developed microgrid model, **Figure 2**, includes the following components: distributed energy sources, distributed storage, backup sources for the generated power, critical or priority energy users (which do not allow any interruptions in the power supply) as well as standard users (which allow power supply interruptions) and one control unit that communicates to all the other components. The standard energy consumers, which can be considered by the

which are not connected to conventional power systems.

**2.1. Architecture of the AC/DC microgrid**

supply, by providing a high level of security;

equipment;

of the end user [6].

and other voltage fluctuations, or other power-quality disturbances.

**2. Microgrid and Energy Management System configuration**

The designed microgrid takes into account the following requirements:

• option to connect to the electric public grid and to operate interconnected;

The two microgrid definitions, which are currently in use, are provided by the US Department of Energy Microgrid Exchange Group and by CIGRÉ C6.22 Working Group, Microgrid Evolution Roadmap, respectively:

*"A microgrid is 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-connected or island-mode"* [2, 3].

*"Microgrids are electricity distribution systems containing loads and distributed energy resources, (such as distributed generators, storage devices, or controllable loads) that can be operated in a controlled, coordinated way either while connected to the main power network or while islanded"* [2, 3].

The microgrid concept supports an alternative approach to the integration of distributed energy resources characterized by low installed capacity to distribution grids [4]. When compared to conventional power systems, the main advantage of microgrids consists of the controllable unit feature. Microgrids can be operated as a single load, ensuring easy control and compliance to rules and regulations without impacting the reliability and safety of the user's power supply.

Microgrids are designed to operate semi-independently, usually in grid-connected mode, providing options for isolated or islanded operation, either for economic, reliability, or

**Figure 1.** The conceptual model of a typical microgrid configuration [6].

security reasons. Also, the development of new energy sources as well as their integration within microgrids allows the supply of some isolated locations, such as islands or mountain areas, which are not connected to conventional power systems.

Currently, a typical microgrid configuration, **Figure 1**, consists of an open architecture, including electrical, communication, command, and control components, which allow the users and energy sources interconnection. Thanks to the capability of offering higher levels for power quality and reliability, a large number of users will adopt power supply solutions based on advanced technology and power electronics in order to minimize voltage sags, interruptions and other voltage fluctuations, or other power-quality disturbances.

Generic microgrids consist of a number of electric generators with static converters as interface modules, electric loads (to be connected either at DC or AC by inverter modules) as well as a connection (by transformer and conversion modules) to the electric distribution grid.

For an optimal microgrid operation, energy management strategies are necessary, proving their utility by adjusting the generated power for each distributed source [5] and by considering the energy storage which currently represents a main component of the energy sector.
