Tracking Aggregate Active-and Reactive-power Setpoints for a Collection of Dispatchable Inverters

This paper proposes a strategy to regulate active-and reactive-power injections of a collection of dispatchable inverters so that the distribution feeder where they are installed can, in aggregate, track active-and reactive-power regulation signals issued by a higher-level aggregator. At its core, the proposed method relies on the linear mapping of nodal active-and reactive-power injections to the active and reactive power injected into the bulk transmission grid and a linear-quadratic-regulator (LQR) controller. We demonstrate the effectiveness of the proposed LQR controller using regulation signals from Pennsylvania-New Jersey-Maryland Interconnection (PJM) for a collection of 15 inverters (each with a 15th-order model capturing phase locked loop, LCL filter, power-and current-controller dynamics) installed in a modified IEEE 37-bus distribution feeder. We also evaluate the ability of the proposed controller to track regulation signals with different sampling and dispatch rates.