Rotor Winding Inter-turn Short Circuit Research Articles

State feedback method of inter-turn short circuit in rotor winding of induction motor based on improved association rule algorithm

Aiming at timely feedback and processing of asynchronous motor rotor windings, a feedback method based on an improved association rule algorithm of asynchronous motor rotor windings is studied. Based on the inter-turn short circuit mechanism of asynchronous motor windings, the fuzzy association rule mining method is used to mine the inter-turn short circuit mechanism of asynchronous motor windings. The method mines the rotor-side electrical parameters as the input of the deep neural network and uses the deep neural network to output the short-circuit state feedback results of the rotor windings of the asynchronous motor. The experimental results show that when the A-phase of the asynchronous motor is the faulty phase, the A-phase current of the rotor winding inter-turn short circuit increases significantly, and the phase angle difference deviation has a positive correlation, which effectively feedbacks the asynchronous motor rotor winding inter-turn short-circuit state.

Weak Fault Detection of Rotor Winding Inter-Turn Short Circuit in Excitation System Based on Residual Interval Observer

Weak Fault Detection of Rotor Winding Inter-Turn Short Circuit in Excitation System Based on Residual Interval Observer

Effect of Pole Number on Generator End Winding Electromagnetic Force and Mechanical Response before and after RISC

This paper comparatively studies on the end winding electromagnetic force and mechanical response for generators with different numbers of poles. The analytical expression of the end winding electromagnetic force is derived under the rotor winding interturn short circuit (RISC) considering the pole number. Meanwhile, the three-dimensional transient finite element simulation is carried on two generators with one-pair poles and three-pair poles. Then, the frequency composition and amplitude variation characteristics of the radial, axial, and tangential electromagnetic forces are analyzed. Further, the maximum stress and deformation on the end winding are calculated and the similarity and difference of the coil failure law are obtained for two kinds of generators. It is found that RISC will bring odd harmonics to electromagnetic force for one-pair pole generators but it will bring odd and fraction harmonics for multipair pole generators. Moreover, the max mechanical response under RISC will decrease for one-pair pole generators but it will increase for multipair pole generators.

Fault diagnosis of rotor winding inter‐turn short circuit for sensorless synchronous generator through screw

Timely and accurate detection of the rotor winding inter-turn short-circuit fault of a synchronous generator can reduce the more serious damages caused by fault deterioration and economic losses, so developing online detection methods with high sensitivity is necessary. On the basis of the structural characteristics of the synchronous generator, this study proposes a sensorless online detection method for rotor winding inter-turn short-circuit faults, respectively, taking a 300 MW turbo generator and a 550 MW hydro-generator as the objects of finite-element simulation. The results show that the new fault diagnosis method of the rotor winding inter-turn short circuit for the sensorless synchronous generator has high sensitivity and can realise real-time monitoring of the faults.

Discrimination of Synchronous Machines Rotor Faults in Electrical Signature Analysis Based on Symmetrical Components

Electrical signature analysis (ESA) has been successfully applied to predictive maintenance of synchronous machines. The fault diagnosis is performed by analyzing failure patterns in the current or voltage spectra, which allow the discrimination of a healthy and a faulty condition on the monitored machine. Generally, the failure patterns are a function of the line frequency, rotor rotation frequency, and some structure features of the machine. The rotor rotation frequency pattern, for instance, is indicative of rotor mechanical problems and rotor winding interturn short-circuit. An increase of this frequency component magnitude may indicate the incipience of a rotor fault but may not discriminate the nature of the fault (electrical or mechanical). Thus, it is necessary to distinguish the effects of electrical and mechanical faults in these components in order to get a reliable diagnosis of the machine. No works have been found in the literature approaching this specific issue. This paper proposes a simple and innovative methodology to distinguish the effect of electrical and mechanical faults in the mentioned ESA failure patterns based on the method of symmetrical components. Its effectiveness is validated by experiments performed on a synchronous generator test rig. The proposed condition monitoring system is simple, low cost, and low intrusive, as it only relies on stator electrical quantities. Moreover, it is in operation in a Brazilian 404-MW thermal power station.

An Analysis of the Impact of Rotor Winding Interturn Short Circuits on Turbine Generator Operating Variables

— In this article, the finite-element method is used to study the impact on a generator's electromagnetic torque by the position and level of a rotor winding interturn short circuit. The rules involving changes to the exciting current and the reactive power of generators are analyzed under the given adjustment patterns. The results of this study show that the saturability of ferromagnetic materials reduces the torque undulations that occur during the rotor winding interturn short circuit fault and that it improves the static stability of generators. Both the simulation experiment and the real case of a rotor winding interturn short circuit demonstrated that when a rotor winding interturn short circuit happens in a turbine generator, the generator can maintain its static stability by adjusting its state variables. This results in an increased exciting current and a decreased reactive power. The analytical method described herein allows accurate prediction of the change limits of the exciting current and the reactive power, enabling better diagnosis of the rotor winding interturn short circuit based on the two variables.

Diagnosis of Rotor Winding Interturn Short-Circuit in Turbine Generators Using Virtual Power

Rotor winding interturn short-circuit (RWISC) occurring in turbine generators has been plaguing power producers with respect to production safety and economy. RWISC is characterized by impaired fundamental component of the exciting magnetomotive force and resultantly reduced no-load electromotive force E 0 . In this paper, an inverse reasoning method is proposed to analyze RWISC. First, it is assumed that the generator's rotor winding is running in good condition and the generator's electromagnetic power (virtual power, VP) is inversely calculated from the obtained operational data on generators. Second, the difference between the virtual power and the actual electromagnetic power is calculated and then used to determine whether an RWISC occurs on the turbine generator. Three real cases of severe rotor winding shorts have demonstrated that this method proposed in this paper not only enables to diagnose RWISC, but also allows determining the RWISC level and its trending accurately. The method is appropriate for RWISC diagnosis, whether offline or online, and can be applied to make the generator sets in the power plant run safer, more economical, and more stable.

Generator vibration fault diagnosis method based on rotor vibration and stator winding parallel branches circulating current characteristics

Rotor vibration characteristics are first analyzed, which are that the rotor vibration of fundamental frequency will increase due to rotor winding inter-turn short circuit fault, air-gap dynamic eccentricity fault, or imbalance fault, and the vibration of the second frequency will increase when the air-gap static eccentricity fault occurs. Next, the characteristics of the stator winding parallel branches circulating current are analyzed, which are that the second harmonics circulating current will increase when the rotor winding inter-turn short circuit fault occurs, and the fundamental circulating current will increase when the air-gap eccentricity fault occurs, neither being strongly affected by the imbalance fault. Considering the differences of the rotor vibration and circulating current characteristics caused by different rotor faults, a method of generator vibration fault diagnosis, based on rotor vibration and circulating current characteristics, is developed. Finally, the rotor vibration and circulating current of a type SDF-9 generator is measured in the laboratory to verify the theoretical analysis presented above.

F311 THE ANALYSIS OF GENERATOR EXCITATION CURRENT HARMONICS ON STATOR AND ROTOR WINDING FAULT

When generator operates normally, armature reaction magnetic field synchronously rotates with rotor, and rotor winding won't induce additional harmonic current. When stator winding and rotor winding inter-turn short circuit fault has happened, armature reaction magnetic field non-synchronously rotates with rotor. So additional harmonic current is induced in rotor winding. Through analyzing electromagnetism characteristic on stator and rotor winding fault respectively, it is known that the additional excitation current harmonic on stator winding fault mainly is twice electrical frequency, and that on rotor winding fault is the function of air-gap excitation magnetic field harmonic frequency, poles' pairs of generator and rotor mechanical revolution. Finally, the excitation current of MJF-30-6 synchronous non-salient pole generator is acquired on stator and rotor winding inter-turn short circuit fault respectively, the results of verification show that the theory analysis is right.