Efficient steady state analysis of the grid using electromagnetic transient models

Abstract

• Time-domain steady-state (TDSS) methodology efficiently solves for an accurate steady-state of the grid using EMT models. • The paper presents a decoupling approach that iterates on a waveform to efficiently solve for the steady-state. • The simulation results highlight improvement in accuracy over power flow while solving in fewer iterations compared to EMT analysis. Modern grids contain an increasing number of non-linear grid devices that are accurately modeled only in the time domain. Performing an accurate steady-state analysis with such models requires a transient simulation to infinite (sufficiently long) time, which can be computationally prohibitive. Power flow provides an efficient, but approximate steady state analysis using models based on a single nominal frequency, which fails to represent the true steady-state. We present a new method for efficiently analyzing the steady state response using traditional transient models that is inspired by harmonic balance methods. Rather than solving the underlying ODE by discretizing time, our method iterates on the entire waveform to find an accurate time domain waveform that captures the steady-state dynamics for all three phases. This presents a novel, efficient methodology for accurately studying the steady-state of the power grid. We introduce the concept by studying the steady state of a 14-bus system under various scenarios and highlight the difference between the steady-states achieved through power-flow and our method that uses EMT models.