An Enhanced Primary and Secondary Control Method for Three Phase VSCs

Under the hierarchical control architecture for dc microgrids (MGs), primary and secondary control cope with preliminary power sharing and maintaining dc bus voltage, respectively. This paper proposes an ac current-dc voltage droop characteristic for the primary level and secondary control approach in the absence of PI controllers and communication links. In addition, state space model is established and corresponding eigenvalues contours with respect to key parameters variations are performed. Based on state apace model of parallel voltage source converters (VSCs), an optimal power distribution can be designed. Eigenvalues analysis and time domain simulations verify that proposed method has a fast dynamic performance depending on current loop and power distribution accuracy with adaptive droop gain.