Peer-to-Peer-Based Power Flow Control in Microgrids With Limited Voltage Harmonic Distortion

Abstract

This paper proposes a novel primary level controller and coupling LCL filter design methodology for microgrid prosumer units The so-called decentralized peer-to-peer-based power flow control algorithm introduces a power exchange communication link between two contractees, namely a prosumer unit and any other unit, on the time scales of primary power flow controller. This can be regarded as feed-forwarding of power flow information between the units in close to real-time in order to attain almost instant power balancing within the system. When coupled with the conventional voltage and frequency droop primary control, as presented in the paper, and tested on a simulation model of one radial microgrid in the off-grid mode of operation, it showed enhanced static and dynamic performance. The study also investigated adverse influence of the communication link time delay. The paper addressed prosumer units microgrid voltage-forming role by proposing design and control methodology for the prosumer units’ LCL coupling filter. To that aim, thorough voltage and current harmonic emission analysis has been conducted, taking into account realistic span of a microgrid parameters’ values and presence of other units. The study and the simulation model tests revealed that the limited total voltage harmonic distortion becomes critical requirement in the off-grid model of operation.

Keywords

• Microgrid
• peer-to-peer power flow
• decentralized control
• droop control
• limited voltage and current THD
• LCL filter design