An enhanced microgrid power sharing strategy based on multiple second order generalized integrators harmonic detection and adaptive virtual impedance

Abstract

When microgrid which adopt droop control operate in island mode, the difference of line impedance from the distributed generation (DG) units to the common coupling point (PCC) will lead to a poor sharing performance of reactive power, harmonic power and unbalanced power. This paper introduces a novel control method based on multiple second-order generalized integrator harmonic detection, which can dynamically adjust the two DG virtual impedance by processing the error between steady active power and transient active power with an integrator. Then the reactive power, harmonic power and unbalanced power control are added through respectively injecting small frequency disturbances to achieve power sharing. The proposed control method achieves accurate reactive power, harmonic power and unbalanced power sharing at the steady state even on the condition that the information of line impedance and AC bus voltage is unknown. Simulation and experimental results verify the effect of the proposed control method.