Distributed three-phase reactive power control of distributed energy resources in distribution systems

This paper proposes a new distributed control method for three-phase reactive power control of distributed energy resources (DERs) in distribution systems. Each DER-connected bus has been equipped with a local bus controller which has bi-way communications with bus controllers at adjacent buses upstream and downstream to the bus under consideration. The reactive powers of a DER-connected bus are adjusted to prevent its monitored buses from voltage violations. When voltage violations occur, the required reactive powers for the bus are determined based on the voltage violations on its monitored buses, and equivalent impedances and phase angle shifting between the substation transformer and the study bus. If the required reactive powers of a DER-connected bus are beyond its capacities, the neighbor DER-connected buses are required to share the additional generations. A new iterative residual splitting distributed control algorithm is proposed to coordinate the reactive powers between DER-connected buses. Each DER unit at a DER-connected bus has been equipped with a local unit controller which has bi-way communications with unit controllers at adjacent units of the same bus as the unit under consideration. A consensus-based distributed control algorithm is used to allocate the total demand among units with respect to their capacities. The test results on a modified IEEE 123-node feeder are given to demonstrate the effectiveness of the proposed method.