In this paper, an Internet of Things (IoT) platform is proposed for Multi-Microgrid (MMG) system to improve unbalance compensation functionality employing three-phase four-leg (3P-4L) voltage source inverters (VSIs). The two level communication system connects the MMG system, implemented in Power System Computer Aided Design (PSCAD), to the cloud server. The local communication level utilizes Modbus Transmission Control Protocol/Internet Protocol (TCP/IP) and Message Queuing Telemetry Transport (MQTT) is used as the protocol for global communication level. A communication operation algorithm is developed to manage the communication operation under various communication failure scenarios. To test the communication system, it is implemented on an experimental testbed to investigate its functionality for MMG neutral current compensation (NCC). To compensate the neutral current in MMG, a dynamic NCC algorithm is proposed, which enables the MGs to further improve the NCC by sharing their data using the IoT platform. The performance of the control and communication system using dynamic NCC is compared with the fixed capacity NCC for unbalance compensation under different communication failure conditions. The impact of the communication system performance on the NCC sharing is the focus of this research. The results show that the proposed system provides better neutral current compensation and phase balancing in case of MMG operation by sharing the data effectively even if the communication system is failing partially.
Neutral current compensation techniques in autonomous wind energy sources
