With the increasing complexity of power system structures and the increasing penetration of renewable energy, driven primarily by the need for decarbonization, power system operation and control become challenging. Changes are resulting in an enormous increase in system complexity, wherein the number of active control points in the grid is too high to be managed manually and provide an opportunity for the application of artificial intelligence technology in the power system. For power flow control, many studies have focused on using generation redispatching, load shedding, or demand side management flexibilities. This paper presents a novel reinforcement learning (RL)-based approach for the secure operation of power system via autonomous topology changes considering various constraints. The proposed agent learns from scratch to master power flow control purely from data. It can make autonomous topology changes according to current system conditions to support grid operators in making effective preventive control actions. The state-of-the-art RL algorithm—namely, dueling double deep Q-network with prioritized replay—is adopted to train effective agent for achieving the desired performance. The IEEE 14-bus system is selected to demonstrate the effectiveness and promising performance of the proposed agent controlling power network for up to a month with only nine actions affecting substation configuration.

Phase shifting transformers (PSTs) are a cost-efficient solution for controlling power flow without additional operating expenses. They can enhance power distribution in transmission systems and increase system capacity, particularly for renewable energy integration. However, existing methods for PST sizing and allocation often rely on DC power flow models, which may lack accuracy, and are typically tested on simplified networks that don't fully capture real-world conditions. Furthermore, these methods often overlook practical challenges, such as space limitations in substations. This paper presents a new methodology for PST sizing and allocation in real power networks. Unlike previous approaches, our method is based on AC power flow calculations and takes into account system requirements, space constraints, and economic factors. The goal is to determine the optimal type, size, phase angle regulation range, and location of PSTs to prevent system overloading under normal and N-1 system conditions.