Transmission Line Dynamics Modeling For Power Electronics-Enabled Control in the Electric Power Systems

Abstract

In the analysis and operation of electric power systems, understanding the rates at which dynamic phenomena evolve is critical. Classically, power systems operate on multiple time scales, with slower mechanical dynamics from synchronous machines, faster electromechanical controls and protection, and very fast electrical dynamics from transmission networks. This time scale separation results in system modeling techniques which neglect certain component dynamics. However, in systems with significant penetration of power electronic devices and under fast time scale phenomena, the rates at which dynamics evolve become less separated, necessitating the modeling of all system dynamics. In large-scale systems, this becomes computationally challenging due to the high dimensionality of the interconnected system model. This work investigates the role transmission line dynamics play at very fast time scales in power systems. Theoretical results are presented to analyze which transmission line dynamics contribute significantly to power system dynamics, allowing for the intelligent incorporation of transmission line dynamics into computationally tractable models. For the first time, the use of control co-design techniques are demonstrated algorithmically to design fast power electronics-enabled control to stabilize unstable dynamics in electric power systems. This technique allows the design of controls, in an iterative way, to create stable interconnected systems. Finally, transmission line modeling impacts on the design of protection on fast time scales is analyzed. This work presents techniques to protect from short circuits in response to load disconnections, and introduces DC circuit breaker configurations to cause current commutation. In the modern day, power systems operators possess the technology to implement fast control of dynamics, however, due to insufficient information on how to model and prepare for them, system operators instead rely on using conventional, overly conservative control schemes. This work aims to bridge this gap by presenting methodologies to incorporate these dynamics into next-generation system models, and how to design control and protection to mitigate the risks these fast dynamics pose.