S M Ferdous

A standalone microgrid in a remote area may frequently experience overloading due to lack of sufficient power generation and/or renewable-based over generation causing unacceptable voltage and frequency deviation, which in turn lead the microgrid to operate with less resiliency and reliability. Conventionally, such problems are alleviated by load shedding or renewable curtailment. Alternatively, such autonomously operating microgrid clusters in a certain geographical area can be provisionally connected to each other to enable power exchange among them to address the problems of overloading or overgeneration more efficiently and cost-effective way. The power exchange link among the microgrids can be of different types such as a three-phase ac, a single-phase ac, or a dc-link. Power electronic converters are required to interconnect such power exchange networks to the three-phase ac microgrids and control the power-sharing amongst them. Such arrangement is also essential to interconnect microgrid clusters to each other with proper isolation while maintaining autonomy if they are operating in different standards. In this chapter, the topologies, and structures of various forms of power exchange links are investigated and an appropriate framework is established under which power exchange will take place. This approach is a decentralized control mechanism to facilitate power-sharing amongst the converters of the neighboring microgrids without any data communication, that can be implemented at the primary level based on the localized measurements. The dynamic performance of the control mechanism for all the topologies is illustrated through simulation studies in PSIM® to verify that such overloading or overgeneration situations can be effectively alleviated through proper frequency regulation. The chapter also presents a comparative analysis of the topologies in terms of stability and sensitivity.