Deriving ARX models for synchronous generators

Abstract

Parameter identification of a synchronous generator based on Phasor Measurement Unit (PMU) data requires autoregressive exogenous (ARX) models. This paper presents ARX model derivation and validation of two synchronous generator models. The first one is a third-order ARX model including electromechanical dynamics, turbine-governor dynamics and primary frequency control. Input of the model is power while output is frequency. The second one is a fifth order generator model extending from the simplified one, with additional rotor flux dynamics and excitation dynamics. Generator terminal voltage is treated as input while real power, reactive power and frequency are treated as outputs. Nonlinear model simulation data from Power System Toolbox (PST) are used as PMU data. The derived ARX models are validated by comparing the measurement outputs with the outputs generated from the ARX models. High matching degrees are observed. The coefficients of the ARX models are also compared based on two approaches: (i) calibration from the known generator parameters and (ii) system identification. High matching degrees are also observed.