UC Berkeley

Due to the massive increase in renewable energy deployment around the world, the distribution level of electric power grids has more active devices than ever before. Many distributed energy resources (DERs) were installed to output the maximum amount of power available without consideration of the grid's status or the presence of other devices. As a result, grid operators can encounter power quality issues, especially voltage volatility, which can stall the adoption of more renewable energy devices. Traditional grid devices that are intended to maintain distribution grid power quality may be insufficient to address today's challenges. While academic literature has proposed many types of approaches to device control, it can favor approaches that are optimization-based at the expense of being impractical for deployment on real distribution grids.

This thesis argues for the analysis of simple, flexible device controls to improve power quality and power delivery. We take a dynamical systems perspective, which provides transparency into the underlying device interactions. This perspective allows us to develop intuition for device interactions and develop safety guarantees that prevent dangerous behavior. For the important problem of computing DER power injections, we take a holistic approach to controller design, where control parameters and DER siting are analyzed to achieve improved voltage stability. Furthermore, this design is achieved without imposing restrictions on the DER communication network. Next, we consider device design under two important modeling scenarios. First, we consider the case of abnormal voltage events, in which there is a strict time limit during which DERs must recover the voltage before devices must disconnect. Then we model the interaction between inverter-based DERs and load-tap changer devices, to determine parameter relationships that guarantee against voltage oscillations. We conclude with a discussion of future work and as synthesize important principles for device control in power systems.