Abstract
An efficient and accurate multi-scale induction machine model for simulating diverse transients in power systems is developed and validated. Voltages, currents, and flux linkages are described through analytic signals that consist of real in-phase and imaginary quadrature components, covering only positive frequencies of the Fourier spectrum. The stator is modeled in the abc phase coordinates of an arbitrary reference frame whose rotating speed is adjusted by a simulation parameter called shift frequency. When the reference frame is stationary at a zero shift frequency, then the model processes instantaneous signals to yield natural waveforms. When the reference frame is set to rotate at the synchronous frequency of the electric network, then the Fourier spectra of the analytic signals are shifted by this synchronous frequency to become dynamic phasors that allow for efficient envelope tracking. The shift frequency can be adapted during simulation. For any rotor position and independent of the variation of the magnetizing inductances with saturation, the induction machine model appears as a Norton current source with constant inner admittance in the abc phase domain to support the integration with simulators that represent the electric network in the abc phase domain. The analysis of test cases covering diverse transients substantiates the claims made in terms of accuracy and efficiency across different time scales.
Highlights
A LGORITHMS for the simulation of transients in electric power systems are commonly classified into two categories
If it is of interest to study both electromagnetic and electromechanical transients within the same study, the concept of frequency-adaptive simulation of transients (FAST) [6]–[10] offers an efficient multi-scale simulation
The virtues of dynamic phasors and electromagnetic transients programs (EMTP)-type modeling techniques are combined by representing all ac quantities through analytic signals and by introducing a variable simulation parameter called the shift frequency
Summary
A LGORITHMS for the simulation of transients in electric power systems are commonly classified into two categories. In [12], the voltage-behind-reactance (VBR) induction machine model providing direct machine-network interfacing was introduced Both the described phase domain and VBR models have rotor-position-dependent equivalent admittance matrices when discretized for EMTP-type solution. The electromagnetic quantities in the difference equations are described through dynamic phasor calculus using shift frequency analysis This allows for larger time-step sizes in representing electromechanical transients compared with the original EMTP-type solution, the admittance matrix is dependent on the rotor position. In [17] and [18], EMTP-type solutions were developed to keep the equivalent admittance matrices of the induction machine models constant in the abc phase domain This advantage is combined with the capability to directly integrate with network models in the phase domain without transformation from the dq0 to the abc frame.
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