Frequency-Weighted Residual Truncation and Padé Approximant for Model Reduction of Power System with Constant Time Delay

Yonghui Nie,Zhunhang Wang,Yan Zhao,Lei Gao,Jiang Li

doi:10.1109/access.2020.2984528

Abstract

To improve the efficiency for managing power systems with constant time delay, an improved frequency-weighted model reduction is proposed. First, the Pade approximant allows to represent the time delay in the state-space form and build a linear model of the closed-loop power system containing a wide-area damping controller. Then, a weight function is introduced to solve the equilibrium transformation matrix and balance the original system. Finally, the residual order reduction is applied to the model of the power system considering time delay. The proposed method is evaluated in the two-area four-machine test system and New England system, and the effectiveness of the proposed reduction method is verified.

Highlights

The increasing scale of modern power systems and adoption of power system stabilizers, flexible ac transmission systems, high-voltage dc transmission, and a myriad of control methods make the dimension of the state variables to sharply increase [1]–[3]
Frequency-weighted truncation can be used for model reduction of the time-delay power system
We can further verify error in the low-frequency band, whereas the high-frequency band error is relatively large, and the high-frequency amplitudes of the two reduced systems have a similar considerable decline compared to the original system, resulting in the abovementioned time-domain changes of the two reduced systems

Summary

Introduction

The increasing scale of modern power systems and adoption of power system stabilizers, flexible ac transmission systems, high-voltage dc transmission, and a myriad of control methods make the dimension of the state variables to sharply increase [1]–[3]. This method has the following advantages: (I) establishes a linear model of the power system using the Padé approximant, (II) guarantees stability of the reduced-order model under input and output weighting, (III) effectively approximates the behavior of the original system regarding low-frequency oscillations, and (IV) employs the reduced-order method with frequency-weighted residuals in model reduction of the power system with time delay to reduce the steady-state error.

Results

Conclusion