Microgrids feature several benefits for consumers, from reliability and resilience to improving energy delivery and integrating/aggregating distributed resources. A microgrid can also provide backup for the critical end-use loads in case of emergencies and allow communities to become more energy independent.
However, one of the largest barriers of deployment of microgrids is the cost. One important reason for this is because of the need for larger diesel generators and/or batteries to address dynamic stability issues associated with smaller microgrids. Because of the relatively small size of the generating units, microgrids are affected more by system disturbances than the bulk power system. The challenge with this approach is if you put a bigger generator or more batteries in just for stability, that’s more capital costs, and when running the microgrid, you’ll have a generator that is larger than needed and only running at a partial load. Partial loads result in more operational costs. To mitigate the need for oversized equipment, control systems are needed to stabilize the microgrid using existing assets. These control system temporarily reduce voltage output of the electrical generators during a transient, to mitigate the frequency variations.
Researchers at PNNL have developed algorithms that can be added to already installed voltage regulators in a microgrid to improve the systems primary frequency response during a transient. When a controller detects a variation in system frequency, it quickly adjusts the output voltage of the electrical generator to oppose the change in frequency, which in turn affects the power consumption of the end-use load. Since the algorithms operate using already existing components, there is no need for additional equipment and/or oversized generators.
Benefits of using properly sized generators include lower capital, operating, and maintenance costs. The capital costs of generators will vary, but a reduction of a 3,500-kVA generator to a smaller 2,500-kVA generator equating to around $550,000 in savings has been cited.
- When capability added to larger system, provides flexibility to reduce overall costs.
- Increases resiliency of system to disturbances.
- Scalable to assist with a variety of grid sizes, including bulk power systems.