Design and Analysis of Flexible Multi-Microgrid Interconnection Scheme for Mitigating Power Fluctuation and Optimizing Storage Capacity

Abstract

With the rapid increase of renewable energy integration, more serious power fluctuations are introduced in distribution systems. To mitigate power fluctuations caused by renewables, a microgrid with energy storage systems (ESSs) is an attractive solution. However, existing solutions are still not sufficiently cost-effective for compensating enormous power fluctuations considering the high unit cost of ESS. This paper proposes a new flexible multi-microgrid interconnection scheme to address this problem while optimizing the utilization of ESSs as well. The basic structure and functions of the proposed scheme are illustrated first. With the suitable power allocation method in place to realize fluctuation sharing among microgrids, the effectiveness of this scheme in power smoothing is analyzed mathematically. The corresponding power control strategies of multiple converters integrated into the DC common bus are designed, and the power fluctuation sharing could be achieved by all AC microgrids and DC-side ESS. In addition, a novel ESS sizing method which can deal with discrete data set is introduced. The proposed interconnection scheme is compared with a conventional independent microgrid scheme through real-world case studies. The results demonstrate the effectiveness of the interconnected microgrid scheme in mitigating power fluctuation and optimizing storage capacity, while at the expense of slightly increased capacity requirement for the AC/DC converters and construction cost for DC lines. According to the economic analysis, the proposed scheme is most suitable for areas where the distances between microgrids are short.

State-of-the-art review on energy sharing and trading of resilient multi microgrids

“… 136 Resiliency assessment of large-scale multi-microgrids Distributed Diffusion Strategy 3 Zhou et al. 137 Seamless interconnection of MMG networks Analytical Approach 2 Farzin et al. 138 Resiliency evaluation with Outage Management Model Predictive Control 3 Kargarian et al.…”

The implementation framework of a microgrid: A review

“… Designing feeders for microgrid: As per the existing the power system, feeders till date are designed based on the strong sources of power generation and distribution. However, a challenge arises when the availability of feeders according to the microgrids demand remains unfulfilled 37‐39 Identifying the microgrid's modes of operation: Each integrated power source vs load scenario in the microgrid should be identified and detailed for instances like temporary switchover or emergency shedding.…”

“…However, a challenge arises when the availability of feeders according to the microgrids demand remains unfulfilled. [37][38][39] • Identifying the microgrid's modes of operation: Each integrated power source vs load scenario in the microgrid should be identified and detailed for instances like temporary switchover or emergency shedding. This step turns to be important and challenging, as microgrid comprises of loads and generation with differently operating nature and behavior.…”

Handbook on Microgrids for Power Quality and Connectivity:

“…However, existing designs are not very cost-effective for handling large power fluctuations unless high capacities of relatively costly energy storage are incorporated. Zhou et al (2019) describe a flexible multi-microgrid interconnection scheme that can potentially optimize the pooled utilization of energy storage across multiple interconnected microgrids as a way to address this cost hurdle, albeit with slightly increased expense for AC/DC converters and DC lines construction, which is most economically viable when distances between the interconnected microgrids are short.…”