From Each According to its Ability: Distributed Grid Regulation With Bandwidth and Saturation Limits in Wind Generation and Battery Storage

The problem addressed here is motivated by distributed control for frequency regulation in the electric power grid, and by the characteristics of new technologies contributing to this control objective: wind generation and battery energy storage. In the large scale, coupled dynamical system of the power grid, we seek a distributed control design approach that can successfully share control effort among two classes of actuators: one class having low bandwidth, but broader actuation limits (controllable power output from wind turbines); and a second class, having narrow actuation limits, essentially zero gain at dc, but much broader bandwidth actuation possible at high frequencies (power output from battery energy storage). In this context, we extend the “saturation-respecting” design methodology developed by Saberi and his co-workers, adapting their low-high gain method with partitioning of slow acting actuator input channels (e.g., wind turbine power changes) from fast acting actuators (battery power delivery). The design methodology, resulting frequency regulation performance, and characteristics of control actuation from individual wind generators and batteries is demonstrated in representative test power system models.