Sun Yuguang

Research on the internal faults of the salient-pole synchronous machine

Adopting the multi-loop method, the mathematical model of the salient-pole synchronous machine is established in which the internal faults can be taken into account. Based on the model, a simulation program of the internal faults is made. It is found that the simulation results are consistent with the experimental data under the same condition, which verifies the mathematical model. According to the simulation results, the variational regularities of transient and steady-state currents are discussed. Referring to a few protective schemes against the internal faults, the protective sensitivities are calculated. Then the sensitivity based on the steady-state fundamental component and that based on the transient fundamental component are compared.

A study of armature winding internal faults and protection schemes for turbogenerators

The internal fault of an armature winding is one of the most severe faults for turbogenerators. It is necessary to know the transient values of the machine when the internal faults occur so as to design suitable protection. Based on the multi-loop method, a mathematical model of the turbogenerator with an internal fault is developed. The air-gap permeance analysis method is used to calculate the parameters and the eddy current of the solid rotor. The method is verified by computer simulation and experimental results. The developed model provides a theoretic basis for predicting transients and developing protection schemes for turbogenerators with internal armature faults.

Comparison of transient and steady-state simulation methods on internal faults of salient-pole synchronous machine

Transient analysis of internal faults in the salient-pole synchronous machine has been seldom discussed so far. In this paper, the mathematical model of the salient-pole synchronous machine, which comprises a group or differential equations with time-variant coefficients, is established using the multi-loop method. Two solution methods, the transient solution and the steady-state solution, are applied to work out the mathematical model. The numerical solutions based on both methods are verified separately by experiments on a 12 kW machine. The paper also compares the two sets of results, pointing out the advantages and limitations of corresponding methods in internal fault analysis.

Transient simulation for stator ground fault in generators based on ML-FEM coupled model

This paper puts forward the ML-FEM coupled model for analyzing the transient behavior of stator ground fault in generators, which possesses the distinguished capability to accurately take account of not only the distributed capacitances of the stator windings to the ground, but a variety of generator nonlinearities. The numerical simulation of stator ground fault in generators, along with the related experiments, has been completed. The simulation and experiment results explicitly demonstrate that the ML-FEM coupled model is superior to the ML model presented previously, and more preferable for transient analysis of stator ground fault in generators. As paves the way to develop and improve the relay protection scheme against this type of fault.