The Analysis and Development of a Power Flow-Based Controller for Microgrid Systems

This paper presents the analysis, development, and implementation of a new controller for microgrid systems. The developed controller is structured to produce command values for the active and reactive powers (P
_C
and Q
_C
), and d-q-axis voltage components (v
_dC
and v
_qC
) for each bus in the microgrid system at hand. Values for P
_C
, Q
_C
, v
_dC
, and v
_qC
are obtained using a power flow formulated in the d-q-axis frame. The d-q-axis power flow (DQPF) produces values for P
_C
, Q
_C
, v
_dC
, and v
_qC
that can meet load demands, respond to variations in power generation within the microgrid, and accommodate the mode of operating the microgrid (interconnected or standalone), while maintaining the voltage and frequency stability. The DQPF-based controller is implemented for performance evaluation using a five-bus microgrid system operated under various conditions, including changes in power generation, step changes in load demands, and changes in mode of operation. Test results demonstrate that the DQPF-based controller can offer simple implementation, accurate and fast responses, and negligible sensitivity to the mode of microgrid operation.