Search

The excitation system with a multi-phase annular brushless exciter (MPABE) is widely used in large-capacity nuclear power plants. It is of great significance to realize a reliable protection of the exciter for safe operation. Since the MPABE is adopted with rotary armature structure, the rotor winding short-circuit (RWSC) fault is very difficult to be diagnosed directly. However, it is an effective way to realize fault diagnosis through the characteristics reflected in the stator field winding. In this paper, based on the mutual induction relationship between stator current and rotor current, detailed theoretical analysis of the RWSC fault is conducted and the harmonic characteristics of the stator field current are obtained. Then, related experiments and simulations are carried out, verifying the correctness of the theoretical analysis. Finally, a diagnosis method based on the transient harmonic characteristics of the stator field current is proposed and its sensitivity is also analyzed. The diagnosis method proposed in this paper is simple and feasible, which helps to improve the safety and reliability of the MPABE system in nuclear power plants. [ABSTRACT FROM AUTHOR]

An excitation system with a multiphase angular brushless exciter is the preferred nuclear power excitation scheme because of its low output voltage ripple. However, interturn short circuits of the stator field windings (ISCFW) often occur in the brushless exciter, affecting the normal operation of the system. To study this type of fault, this paper presents research on theoretical analysis, simulation calculation, and model machine experiments. First, through the analysis of the magnetomotive force produced by windings and their interaction in the air gap under fault, the frequency domain characteristics of the postfault steady-state current are obtained. A general multiloop-method-based mathematical model of multiphase angular brushless excitation system with ISCFW is established. Correlated simulations and experiments with ISCFW are carried out, verifying the result of the theoretical analysis: m/P times harmonics are in the field current, while all harmonics are in the armature current. The general theoretical analysis method and mathematical modeling method proposed in this paper provide a basis for the protection scheme to rapidly remove ISCFW that occurs in the multiphase angular brushless exciter. [ABSTRACT FROM AUTHOR]

Electric propulsion is widely used in ship propulsion systems, and multiphase machines are gaining increasing popularity because of their fault‐tolerant ability, high power density, and reduced torque ripple. This study concentrates on the tandem ship propulsion configuration with two 15‐phase induction machines (IMs) fixed on the same shaft. Based on field‐oriented control and reconfiguration fault‐tolerant control for the single 15‐phase IM, the master–slave coordinated control strategy is designed for the tandem motors, which can not only achieve power allocation between two motors during normal operation, but also minimise the total stator copper loss of the two motors and maximise the propulsion output power ability during fault‐tolerant operation. Experiment results from a ship propulsion experimental platform verify the effectiveness of the proposed control strategies. [ABSTRACT FROM AUTHOR]

This paper studies the electromagnetic torque (EMT) of a nonsalient-pole synchronous generator with the interturn short circuit of field windings (ISCFW). First, the virtual displacement method serves as a basis for analyzing the postfault steady-state harmonic characteristic of EMT. The interactions among various space magnetic fields with different orders, speeds, and rotation directions generated by the stator and rotor are considered. A general conclusion on the EMT characteristics under the fault is then derived. Second, based on the connection conditions of the rotor and stator windings under the fault, the voltage and flux relationships among each circuit are analyzed and the calculation model of the EMT under the fault is built. Through comparisons among the simulations, experiments, and theoretical analyses, the correctness of the calculation model is verified. In addition, a three-pole-pair nonsalient-pole synchronous generator after transformation is used for the case study. The calculation and analysis results indicate that ISCFW generates ac pulsation components with their harmonics closely linked to the stator winding configuration. This paper deepens the fault mechanism of ISCFW and lays a foundation for fault monitoring based on mechanical characteristics. [ABSTRACT FROM AUTHOR]