Analysis of an offshore medium voltage DC microgrid environment — Part I: Power sharing controller design

The AC microgrid is proposed as a plug-and-play interface for various types of renewable generation resources. The fundamental microgrid requirements include the capability of operating in islanding mode and/or grid connected modes. The high-level technical challenges associated with microgrids include (1) operation modes and transitions that comply with IEEE1547 and (2) control architecture and communication. Proposed control layers and respective functions have been defined in the microgrid literature. These layers include the primary, secondary and tertiary control. In this work, the focus is on the design of a power management secondary control for an offshore DC microgrid serving induction motor drives. The power is managed through a secondary controller to adjust the power delivered through bidirectional DC/DC converters, which intertie with the inverters connected to the machine loads. Simulations in Matlab/Simulink demonstrate the system performance under a mechanical torque step change for one motor drive unit with other conditions fixed. Part I of the concept emphasizes the electrical layout and part II, a communication layout of the offshore platform is described.