Simulation Of Synchronous Machine Research Articles

Application of Local Fourier Transform to Mathematical Simulation of Synchronous Machines with Valve Excitation Systems

Abstract The article proposes a method of mathematical simulation of electrical machines with thyristor exciters on the basis of the local Fourier transform. The present research demonstrates that this method allows switching from a variable structure model to a constant structure model. Transition from the continuous variables to the discrete variables is used. The numerical example is given in the paper.

A Comparative Study of Two Synchronous Machine Modeling Techniques for EMTP Simulation

Modeling and simulation of synchronous machines are traditionally based on the dq-axis model. An alternative method that uses direct phase-domain representation has been proposed over the past 30 years. One of the recent contributions , which is published as a letter in the June 2001 edition of Power Engineering Review , claims that the dq-axis model will give erroneous results in some cases, while the phase-domain model does not have such problems. This is a very bold claim. The purpose of this letter is to verify the conclusions of that Letter. Our simulation results indicate that both modeling methods produce very similar results. The letter's conclusion might have resulted from a misuse of the PSCAD/EMTDC software.

Simulation of synchronous machines in phase coordinates including magnetic saturation

This paper describes a novel way to account for magnetic saturation for simulation of synchronous machines in phase coordinate for power system studies. A synchronous machine model in phase coordinates is presented and the effect of saturation along direct and quadrature axes are taken into account by identifying the flux linkages of individual phases in terms of the flux linkages of direct and quadrature axes. The proposed model was simulated using the high-level dynamic simulation language (DSL) and its performance was compared with the standard dqo model in SIMPOW™ for a sample round rotor machine.

Efficient dynamic synchronous machine simulation with harmonics

Within this paper, an efficient procedure for the dynamic simulation of faulted synchronous machines operating in the presence of harmonics is presented. The algorithm employs steady-state frequency domain techniques for simulation of the transmission system sequence networks and time domain methods for synchronous machines represented in the odq frame of reference. The procedure affords greater accuracy than conventional fault analysis techniques based strictly on steady-state methods, yet requires far less computational time than full system dynamic simulations such as those using the EMTP.

Finite element analysis in electromagnetic systems-accounting for electric circuits

Two approaches for the numerical simulation of electromagnetic systems, accounting for electric circuit equations, are presented. First, the indirect coupled model, which permits the simulation of synchronous machines fed by controlled inverters with moderate calculation time is considered. Second, a direct coupled model where the magnetic and electric circuit equations (2-D or 3-D) are solved simultaneously is developed. This approach takes more calculation time but gives more precision. Applications concerning several electromagnetic systems are treated, and numerical results are compared with experimental ones to verify the validity of the models.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Calculation of saturated inductances for numerical simulation of synchronous machines

In this paper, a method permitting the determination of saturated inductances in synchronous machines as function of time is proposed. A numerical procedure using the finite element method is used to determine expressions of the inductances from the field distribution in the machine. These expressions are introduced in the variable coefficient differential equations of the machine. These equations are solved, using step-by-step numerical integration. Numerical applications are given for three types of machines, salient poles, non salient poles and permanent magnet machines.

Adaptive Control of a Synchronous Generator

Theoretical aspects are based on PARK's equations while the experimental part is achieved from on-line machine frequency responses on small signals for different active or reactive powers. The concordant results show that a third order multi-input-multi-output non minimum phase system characterizes correctly the dynamic behaviour of the synchronous machine and that this system varies greatly with the load.The system characteristics militate in favor of using an adaptive controller.It is the subject of the second part of the paper.The numarical controller is composed of two parts. The first one is concerned with the static non-linear behaviour of the system.The second one must correct the defectiveness of the static model and stabilize the system around a steady state point defined by the same static model.This dynamic control part is getting more complex, as the controlled system is multi-input-multi-output, depends on steady state point, and has sometimes a non-minimum phase behaviour. The chosen control structure is of parellel type, with a memoryless direct action in order to compensate the secondary effects of parametric adjustings and to account implicitely for the strong non linearities of the command. Examples of synchronous machine simulation show the good behaviour of the control system in case of minimum phase.

Dynamic simulation of synchronous machines interconnected by long, compensated transmission circuits

Systems incorporating long, compensated transmission lines operating in conjunction with salient-pole hydro-generators, necessary in the full utilisation of hydropower in remote regions, may operate in particular modes that do not occur with the more conventional power systems. When series-capacitor compensation is used, the line natural frequencies are modified and an extra oscillatory mode is introduced at a frequency which may interact with the machines in the system and cause instability. The paper reports on a study of transmission-system initiated oscillations at subsynchronous frequency, brought about by the introduction of series compensation, and self-induced oscillations at a frequency coinciding with the electromechanical natural frequency of the individual machines. A mathematical model of the complete system is developed that is suitable for use in computer studies. Representative results, from the numerous studies based on this model, are collected together in the paper, and are used to show the conditions which give rise to the two categories of instability.

An Improved Teaching Simulation of Synchronous Machines

An Improved Teaching Simulation of Synchronous Machines

Direct Simulation of AC Machinery Including Third-Harmonic Effcts

A method is described for simulating noncommutating electrical rotating machinery. The method is based on the expression of actual coil voltages and currents directly as contrasted with methods in which these coordinates are transformed along special axes. The voltage equations are integrated before computer simulation. This means that voltage inputs to the computer become integrated voltage inputs. Effectiveness of the method is demonstrated by simulating an electromagnetically balanced two-phase induction machine with input voltages of different frequencies. The simple addition of dc input to a rotor coil makes a synchronous machine simulation, which is illustrated for transient starting and short-circuit conditions. The straightforward representation of space MMF harmonics is demonstrated by the addition of a third harmonic of space distribution to the basic simulation. The method should be desirable for analysis of inverter or cycloconverter systems. It can be easily extended to unsymmetrical machines, and there are no restrictions against unsymmetrical inputs, as is amply illustrated by the results obtained with such extreme dissymmetry as inputs of different frequencies.