Smart Inverter for Voltage Regulation: Physical and Market Implementation

Lack of efficient coordination schemes between photovoltaic (PV) panels may result in voltage stability issues. In this paper, we exploit the power control potential enabled by the PV inverters for voltage regulation. There are considerable obstacles to design a viable coordination scheme. Physically, the power flow equations lead to a highly nonconvex constraint set. With respect to the market implementation, voltage regulation is predominately conducted by the system operator, and voltage regulation related products rarely exist. We cast the voltage regulation as a nonconvex optimization problem, and devise an analytical framework to show that based on a linearized model, one can design a gradient descent-based distributed scheme, which, when implemented in the nonconvex branch flow model, will converge to a local minimum exponentially fast. Additionally, we design a compensation scheme which incentivizes the PV panel owners to provide voltage regulation. The compensation naturally leads to a game between all the PV panel owners. By design, the equilibria coincide with the global minimizers to the social planner problem. Simulation results confirm the convergence rate of the control actions in practice.