| REPRESENTATION OF FAULTS IN MATHEMATICAL MODEL OF CONVERTOR SET | ||||||
| Author(s) | Ewa Napierulska-Juszczak | |||||
| Abstract | Diode faults in network commutated convertors provide unidirectional currents strongly submagnetizing the convertor transformer. After a few periods very high saturation of the core appears. If the fuses are wrong the transformer windings undergo very peculiar dynamic strains, generally more dangereous than during usual S.C. To obtain proper wave shapes of all currents, voltages, main, leakage and so called yoke fluxes enabling the analysis of transient phenomena, the design of adequate equivalent circuit and formation of mathematical model are necessary. It has to consider the magnetic non-linearity and non-symmetry of the core, saturation of smoothing reactor, properties of diodes and SCR. This paper presents an equivalent circuit for three phase bridge with 20 nonlinear equations forming the mathematical model. It allowes the analysis of transients during all possible faults, changes of load, EMF, or impulsing angle, disconnections, blowing of fuses etc for rectifier and invertor operation. Following phenomena are analyzed as instances: a/ short circuit of one diode in a 6 D set; b/ short circuit on DC terminals in 6 T bridge with only a nonlinear smoothing reactor; stoping impulses when IDC > 5 In; c/ same as "a" but in 6T set. The results are computed and compared with experiments with good agreement. |
|||||
| Download |
|
|||||
| Type | Members Only | |||||
| Date | Last modified 2021-02-08 by System | |||||
 |
||||||