Just a few years ago, microgrids were simple. A diesel generator sat for long periods until a facility manager manually disconnected the site from the grid. The generator ran until the power came back on or the fuel supply ran out. All in all, managers faced a limited number of decisions when it came to managing a microgrid.
Now, microgrids are much more complicated. They often have multiple generation sources, battery storage systems, controllable energy consumption devices and have live connections to the grid. It has become essential for microgrids to be intuitive when it comes to knowing what to do and when. This helps ensure the best outcome for the lowest cost.
Here is where optimization comes in. Granted, some think optimization is a buzzword, created to sound impressive without any specificity. The fact is understanding the values of various types of optimization helps ensure microgrid owners meet their goals. Optimization automates the best results for a system, considering its site-specific limitations. Optimization is made up primarily of four core concepts:
- Objective function: It defines the objective of the solution. For example, the objective could be to minimize the cost for supplying load. How the control variables influence that cost must be known
- Control Variables: These are the levers you can use to achieve your objective. For microgrid operations, typical control variables are power output of generating/storage units or load connection statuses, etc.
- Constraints: Constraints address the laws of physics such as generation output cannot be outside of the operating range of the generating unit or the load must exactly match the generation
- Model: The optimization works on a model, where the model defines number of entities (DERs) participating in the optimization, the constraints, the relationship of the control variables to the objective function etc.
A technique that strictly adheres to these principles and method of solving a problem is referred to as “optimization”. The optimization “engine” finds the optimal values for the control variables that result in achieving the objective while respecting the constraints.
Here are some good starting points for anyone interested in optimizing a new microgrid project.