Two-Timescale Voltage Control in Distribution Grids Using Deep Reinforcement Learning

TL;DR

This paper introduces a two-timescale voltage control scheme for distribution grids that combines deep reinforcement learning and physics-based optimization to effectively manage voltage fluctuations caused by renewable energy and electric vehicles.

Contribution

It proposes a novel joint control framework coupling fast smart inverter adjustments with slow capacitor switching using deep reinforcement learning.

Findings

Effective voltage regulation demonstrated on real-world and IEEE test feeders.

Significant reduction in voltage deviations achieved.

Outperforms traditional control methods in dynamic scenarios.

Abstract

Modern distribution grids are currently being challenged by frequent and sizable voltage fluctuations, due mainly to the increasing deployment of electric vehicles and renewable generators. Existing approaches to maintaining bus voltage magnitudes within the desired region can cope with either traditional utility-owned devices (e.g., shunt capacitors), or contemporary smart inverters that come with distributed generation units (e.g., photovoltaic plants). The discrete on-off commitment of capacitor units is often configured on an hourly or daily basis, yet smart inverters can be controlled within milliseconds, thus challenging joint control of these two types of assets. In this context, a novel two-timescale voltage regulation scheme is developed for distribution grids by judiciously coupling data-driven with physicsbased optimization. On a faster timescale, say every second, the optimal setpoints of smart inverters are obtained by minimizing instantaneous bus voltage deviations from their nominal values, based on either the exact alternating current power flow model or a linear approximant of it; whereas, on the slower timescale (e.g., every hour), shunt capacitors are configured to minimize the longterm discounted voltage deviations using a deep reinforcement learning algorithm. Extensive numerical tests on a real-world 47- bus distribution network as well as the IEEE 123-bus test feeder using real data corroborate the effectiveness of the novel scheme.