Stability Preservation and Power Management in Autonomous Microgrids using adaptive non-linear droop scheme

This paper proposes sharing active and reactive power in autonomous voltage source inverter (VSI)-basedmicrogrids with no physical communication links. In decentralized VSI-based microgrids, when the demand or generationchanges, the output voltage of distributed generation units and the frequency of the system will also change. This studypresents a novel adaptive nonlinear droop (ANLD) scheme for preserving network stability, improving the system'sdynamics, and controlling power sharing in multibus microgrids in a decentralized manner. Subcontrollers are modeledin a state space and combined together so that a complete dynamic model of the network can be developed. Note thatcontroller coefficients are optimized to improve small-signal stability and to obtain a good operating point. To this end,an optimization problem is formulated and solved using the particle swarm optimization method. For the purposes ofcomparison, the proposed ANLD method and three other schemes are applied to two case studies: a 5-bus microgrid anda modied 37-bus IEEE microgrid. The stability margin analysis and time response simulations prove that the proposedalgorithm performs much better and can be applied to large-scale microgrids.QC 20170405Autonomous microgrid, droop control, load sharing, small-signal dynamics, voltage source inverter mode