Accurate Load Demand Sharing Strategy in a Grid Connected Network
Keywords:Distributed generation (DG), droop control, low-bandwidth communication, microgrid, reactive power compensation, real and reactive power sharing.at location in the distribution system
For the operation of autonomous microgrids, an important task is to share the load demand using multiple distributed generation (DG) units. In order to realize satisﬁed power sharing without the communication between DG units, the voltage droop control and its different variations have been reported in the literature. However, in a low-voltage microgrid, due to the effects of non- trivial feeder impedance, the conventional droop control is subject to the real and reactive power coupling and steady-state reactive power sharing errors. Furthermore, complex microgrid conﬁgurations (looped or mesh networks) often make the reactive power sharing more challenging. To improve the reactive power sharing accuracy, this paper proposes an enhanced control strategy that estimates the reactive power control error through injecting small real power disturbances, which is activated by the low-bandwidth synchronization signals from the central controller. At the same time, a slow integration term for reactive power sharing error elimination is added to the conventional reactive power droop control. The proposed compensation method achieves accurate reactive power sharing at the steady state, just like the performance of real power sharing through frequency droop control. Simulation and experimental results validate the feasibility of the proposed method.
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