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UBC Theses and Dissertations

Analysis of electromagnetic and electromechanical power system transients with dynamic phasors Henschel, Sebastian

Abstract

Over the last 50 years, digital simulation of electric power systems has become an integral part for planning, design and operation in the power industry. The number of possibilities with respect to the purpose of a study, investigated frequency ranges, etc. with, in the past, limited computer resources has resulted in a spectrum of simulation tools, designed to handle very specific tasks. Simplifying assumptions were often needed to facilitate such a simulation. Recent system failures and power outages, partly due to increasingly sensitive operating conditions, have created a demand for more comprehensive studies and more general simulation tools that overcome former limitations. With regards to time-domain simulation, this demand has led to combining the areas of transient, mid-term and long-term stability. Confronted with concerns about black start and system restoration due to a global trend to a deregulated power market, several power utilities suggested to also include the area of electromagnetic transients. However, previously made assumptions as well as technical limitations complicate the implementation of this idea: Stability programs are based on the assumption that power transfer takes place at system frequency and are therefore unable to represent rapid electromagnetic transients. Electromagnetic transients programs, on the other hand, are very accurate but use too small simulation step sizes for an efficient simulation of electromechanical transients. A new method for simulating both types of transient phenomena with complex signals and dynamic phasors is presented in this thesis. Whereas in previous work three-phase transformations had been used to accomplish this task, this new method is applied directly in the phase-domain and not restricted to balanced three-phase systems. Several numerical aspects such as an appropriate variable representation, integration method and a control mechanism for variable simulation step sizes have been addressed. Important modeling constraints for transmission lines and synchronous machines have been thoroughly analysed and are considered in this work. Finally, several simulation examples are presented that compare the results of the new simulation program with the results obtained from the EMTP. These case studies demonstrate that the methods presented in this thesis are suited to combine the areas of electromagnetic and electromechanical transients simulation.

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