Active Synchronizing Control of a Microgrid

• Published in: IEEE transactions on power electronics 2011-12, Vol.26 (12), p.3707-3719
• Main Authors: Cho, Changhee, Jeon, Jin-Hong, Kim, Jong-Yul, Kwon, Soonman, Park, Kyongyop, Kim, Sungshin
• Format: Article
• Language: English
• Subjects: Alternative energy sources; Applied sciences; Circuit properties; Circuits of signal characteristics conditioning (including delay circuits); Control systems; Direct energy conversion and energy accumulation; Electric power; Electric, optical and optoelectronic circuits; Electrical engineering. Electrical power engineering; Electrical power engineering; Electronic circuits; Electronic equipment and fabrication. Passive components, printed wiring boards, connectics; Electronics; Energy accumulation; Energy storage system; Exact sciences and technology; Frequency synchronization; Generators; microgrid; microgrid central controller (MCC); Miscellaneous; network-based control; Power networks and lines; Power system reliability; Simulation; static transfer switch (STS); Synchronization; Voltage control
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2011.2162532

A microgrid is an aggregation of multiple distributed generators (DGs), such as renewable energy sources, conventional generators, and energy storage systems that provide both electric power and thermal energy. Typically, a microgrid operates in parallel with the main grid. However, there are cases in which a microgrid operates in an islanded mode, or in a disconnected state. Islanded microgrid can change its operational mode to grid-connected operation by reconnection to the grid, which is referred to as synchronization. Generally, a single machine simply synchronizes with the grid using a synchronizer. However, the synchronization of microgrids that operate with multiple DGs and loads cannot be controlled by a traditional synchronizer. It is needed to control multiple generators and energy storage systems in a coordinated way for the microgrid synchronization. This is not a simple problem, considering that a microgrid consists of various power electronics-based DGs as well as alternator-based generators that produce power together. This paper proposes an active synchronizing control scheme that adopts the network-based coordinated control of multiple DGs. From the simulation results using Simulink dynamic models, it is shown that the scheme provides the microgrid with a deterministic and reliable reconnection to the grid. The proposed method is verified by using the test cases with the experimental setup of a practical microgrid pilot plant.