Doctoral Dissertations

Date of Award

5-2024

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Electrical Engineering

Major Professor

Kai Sun

Committee Members

Fangxing “Fran” Li, Xiaopeng Zhao, Bin Wang

Abstract

This dissertation investigates efficient power system electromagnetic transient (EMT) simulations using a semi-analytical approach.

First, based on state-space equations of system EMT models, a semi-analytical solution (SAS) is acquired using the Differential Transformation Method (DTM). The DTM can efficiently derive the SAS of any linear or nonlinear system as a power series in time in a recursive manner using well-developed transformation rules. A high-order SAS allows a large time step to speed up the simulation while maintaining the same level of accuracy. Also, a variable time step approach is proposed to further improve its efficiency. Case studies on multiple systems demonstrate that the proposed approach has better performance compared to traditional numerical approaches.

Second, to effectively handle switches caused by limit violations during simulations, a binary search-enhanced quadratic-interpolation algorithm is proposed to precisely locate the transition moment and correct the simulation using the SAS. Case studies on a full EMT model of the IEEE 39-bus system are conducted to show the high accuracy of the proposed detection approach.

Third, while the network is solved by a nodal equation instead of a state-space equation, the SAS is explored on synchronous generators and controllers. An interface between the two different numerical approaches is developed based on the extrapolation of terminal voltages. At the same accuracy, the SAS can still improve the simulation efficiency using a larger time step.

Fourth, the parallel SAS-based EMT simulation using a nodal equation for the network is studied and tested. The network solution is parallelized through reformulating the network conductance matrix into a bordered block diagonal (BBD) form. The SAS-represented synchronous generators are naturally decoupled and parallelized. Case studies on a synthetic 10024-bus system demonstrate the high performance of the parallel simulation.

Fifth, a high-order nodal approach for the network equation based on diagonally implicit Runge-Kutta methods is proposed and interfaced with the SAS of generator and controller equations. Case studies on a four-bus system show that the proposed approach has higher efficiency compared with the traditional approach.

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