A microgrid is a power generation system that is contained within a localized area that operates either independently of or connected to a main utility grid. Microgrids may contain both renewable and traditional generation sources and may include energy storage to offset the variability of renewable sources.

Microgrid power stability is more susceptible to changing loads due to its lack of rotating inertia and reliance on inverter-based resources. Also, the distributed generation coupled with bidirectional power flows increase the complexity of operation in the microgrid.

A microgrid can operate when connected to a utility grid (grid-connected mode) or independently of the utility grid (standalone or islanded mode). In islanded mode, the system load is served only from the microgrid generation units. In this mode, the microgrid control regulates voltage and frequency of generation units using grid-forming control. In grid-connected mode, the utility grid commands the voltage and frequency of the microgrid, and the microgrid control regulates active and reactive power from generation units using grid-following control.

Microgrid control includes multiple modes to ensure stable and secure operation:

1. Grid Synchronization: In this microgrid control practice, the magnitude, frequency, and phase of microgrid voltage is matched to the utility voltage before connecting. If the voltages are not matched to within a certain tolerance, large transients can occur on connection, which introduces instability and can result in hazardous operation and equipment damage.
2. Grid Forming: In this microgrid control practice, certain generation units are under voltage and frequency control on an AC system and voltage control on a DC system. An islanded microgrid is incapable of operating in a secure and stable manner if grid-forming control is not present.
3. Grid Following: In this microgrid control practice, certain generation units are under active and reactive power control on an AC system and power control on a DC system. Grid-following units do not directly contribute to voltage and frequency control and instead “follow” the voltage and frequency conditions at their terminals.
4. Curtailment: This microgrid control practice reduces generation and/or load power. The main reason to curtail generation/load is to maintain security and stability when unplanned events occur or when operational conditions stress the grid.

Microgrid control modes can be designed and simulated with MATLAB^®, Simulink^®, and Simscape Electrical™, including energy source modeling, power converters, control algorithms, power compensation, grid connection, battery management systems, and load forecasting. 

Microgrid Control Design with MATLAB and Simulink

With MATLAB and Simulink, you can design, analyze, and simulate microgrid control systems. Using a large library of functions, algorithms, and apps, you can:

• Design a microgrid control network with energy sources such as traditional generation, renewable energy, and energy storage.
• Model inverter-based resources.
• Develop microgrid control algorithms and energy management systems.
• Assess interoperability with a utility grid.
• Analyze and forecast load to reduce operational uncertainty.
• Match the level of model fidelity to the engineering question being addressed, from early-stage feasibility through in-service operation.
• Implement microgrid control algorithms and models to embedded targets, real-time systems, and cloud platforms.

To learn more about how to design a microgrid control system with MATLAB and Simulink, see Simscape Electrical, Control System Toolbox™, and Optimization Toolbox™.