Winding Inter-turn Short Circuit Fault Research Articles

Stator Winding Inter-Turn Short-Circuit Fault Modeling and Detection of Squirrel-Cage Induction Motors

Stator Winding Inter-Turn Short-Circuit Fault Modeling and Detection of Squirrel-Cage Induction Motors

Characteristics Analysis of Field Winding Inter-Turn Short-Circuit Fault for Large-Capacity Synchronous Condenser Based on Stator Winding Asymmetric Branch Current

Characteristics Analysis of Field Winding Inter-Turn Short-Circuit Fault for Large-Capacity Synchronous Condenser Based on Stator Winding Asymmetric Branch Current

The Effect of Stator Inter-Turn Short-Circuit Fault on DFIG Performance Using FEM

Doubly-Fed Induction Generators (DFIG) are operated for wind energy production, and as their capacity is increasing, their safety and reliability become more important. Several faults affect the performance of DFIG. The stator winding Inter-Turn Short-Circuit Fault (ITSCF) is one of the most prevalent electric machine failures. This study examined the stator ITSCF effects on DFIG performance for different cases. The DFIG was designed and engineered using the Finite Element Method (FEM) and the Maxwell software, and was examined in healthy operation and four defective cases with various Numbers of Inter-Turn Short Circuit Faults (NITSCF): 4, 9, 19, and 29. These models allowed the examination of the effects and the comparison of each case separately from the healthy state. The comparison was plotted in Matlab to show the effects of the faults. The novelty of this study was that it investigated the effects of different NITSCF on the performance of DFIG and not only on their effect on the stator current and distribution of magnetic flux density. A better understanding of the short circuit effects on the performance of the DFIG can be exploited for subsequent implementations of early fault detection systems.

Equivalent Broadband Electrical Circuit of Synchronous Machine Winding for Frequency Response Analysis Based on Gray Box Model

Frequency response analysis (FRA) is a popular tool to detect transformer winding deformation faults. It has been recently used to diagnose the winding inter-turn short circuit fault of the electric machine. The application of FRA is based on the fact that the winding can be equivalent to an electrical circuit consisting of resistance, inductance, and capacitance. Therefore, to obtain an accurate broadband equivalent circuit model of synchronous machine and perform the fault analysis and diagnosis, this paper introduces the gray box model technique based on the state space and genetic algorithm. The electrical circuit of a form-wound coil of a 4 kW machine with known electrical parameters is used to verify the proposed method primarily. Besides, the equivalent circuit modeling is carried out and experimentally verified on an actual 5 kW synchronous machine. Finally, the fault simulation analyses of winding inter-turn short circuits are performed based on the proposed equivalent electrical circuit. The verification result shows that the circuit parameters identified by the proposed method are accurate. Moreover, the fault simulation results indicate that the inter-turn short circuit faults can cause apparent variations in the frequency response curves. It is feasible to detect the winding fault of the synchronous machine by the FRA method.

Electromagnetic Torque Characteristics Analysis of Nuclear Half-Speed Turbine Generator with Stator Winding Inter-Turn Short Circuit Fault

To research the variation characteristics and influence factors of air gap magnetic field and electromagnetic torque of nuclear power half-speed turbine generator with stator winding inter-turn short circuit, the two-dimensional transient electromagnetic field of generator-external circuit-grid coupling mathematical model is established by field-circuit-network coupling method. Taking the national laboratory’s generator as an example, and comparing the simulation results of the inter-turn short circuit of the armature winding with experimental data, the correctness of the model is validated. On this basis, the simulation model of a 1407MVA nuclear power half-speed turbine generator is built. Then the stator winding inter-turn short circuit fault is simulated when the generator is connected to the grid with rated load. The characteristics of air gap flux density and electromagnetic torque are obtained before and after fault, as well as, the relationship between their each component and the fault degree is obtained. At the same time, the variation law of air gap flux density and electromagnetic torque is obtained when the relative position between fault winding and magnetic pole changes. The theoretical reference for fault diagnosis and localization using harmonic electromagnetic torque after fault is provided.

Interturn short‐circuit fault diagnosis in PMSM with partitioned stator windings

A new signal-based strategy for stator winding interturn short-circuit fault detection and isolation in permanent magnet synchronous machines (PMSM) is proposed. The strategy is based on an analysis of the midpoint voltage of the phase windings. A PMSM model with partitioned stator windings including an interturn short-circuit fault is presented. Unlike the motor current signature analysis methods, the midpoint voltage measurement allows detecting an incipient stator fault even under external disturbances without false alarms. For PMSM generators used in variable-speed wind turbines, the random changes of wind produce fluctuations in the rotor speed. In this situation, conventional fault detection methods used for the steady-state condition may produce errors in the fault diagnosis. However, the proposed strategy is capable of rejecting the effects of the non-stationary speed conditions by resampling the voltage signals at fixed increments of the rotor angular position. Several experimental results in time and frequency-domain are presented for different speed conditions using a PMSM with modified stator winding.

Research on Electromagnetic Noise of Claw Pole Alternators Under Stator Winding Interturn Short Circuit Faults

This paper proposes a novel simulation method to analyze the characteristics of the electromagnetic noise of claw pole alternators under stator winding interturn short circuit faults. For the two types of faults: short circuit between two wires of the same phase and short circuit between turns of the same wire, a general circuit model built in Matlab/Simulink was introduced to obtained the phase current and output current signals. The phase current was then used as current source and the claw pole alternator was simulated as an electric motor rather than a generator to analyze the magnetic force and electromagnetic noise by using 3-D finite element method and boundary-element method, respectively. A noise bench test was conducted to verify the simulation results. It is shown that under the stator winding interturn short circuit faults, the output current harmonics and electromagnetic noise of the three-phase 12-pole/36-slot claw pole alternator would increase greatly. The 12th order noise replaces the 36th order noise as the most dominant order noise at low speed. The method proposed in this paper can also be used to diagnose the stator winding interturn short circuit faults of claw pole alternators.

Real time observer-based stator fault diagnosis for IM

This paper proposes a delta connected IM model that takes the Stator winding Inter-Turn Short Circuit (SITSC) fault into account. In order to detect the fault and evaluate its severity, an observer based FDI method is suggested. It allows the generation of residual using extended Kalman filter (EKF). To overcome the problem of the EKF initialization, the cyclic optimization method is applied to determine its tuning parameters. The advantage of the proposed approach is the real-time quantification of the fault severity and the quick fault detection. Using numerical simulation under both the healthy and the faulty conditions, the proposed IM model and EKF-based FDI approach are confirmed. Experimental results obtained by a real-time implementation on test-bench validate the simulated results.

Research on current imbalance law of bus - bar caused by inter - turn short circuit of dry-type air - core reactor

Dry-type Air-core Reactor is widely used in power system. It is an important reactive power compensation equipment in power system. In recent years, the dry air reactor has suffered a number of failures in operation. The failure occurred most frequently in the dry-type air-core reactor and we cannot detect the inter-turn short circuit faults in neither single wire winding nor multiple wire windings. The research and protection of reactor faults is almost in the blank at present. This paper presents the method of collecting the unbalanced current between bus-bars to detect the winding inter-turn short circuit faults. The numerical simulation of short circuit model between different windings of the reactor is carried out. Current-differential analyzed on the unbalanced current data of experiment are used to determine whether an inter-turn short circuit occurs. The results indicated that the closer the short-circuit is to the end of the reactor, the greater the unbalance current is. The changes of collecting current between bus-bars are much larger than the total current. Short-circuit current redistribution only occurs between two windings after the short circuit. The circuit in other windings is almost unchanged.

Multifield Calculation and Analysis of Excitation Winding Interturn Short Circuit Fault in Turbo-Generator

Excitation winding interturn short circuit (EWISC) is a common fault in turbo-generators. Once the fault occurs, if not handled in time, it will result in significant security risks to the power system. Using the multifield characteristics of fault generators for a comprehensive diagnosis can make the diagnostic results more accurate and credible. In this paper, taking a TA-1100-78 type, two pole pairs turbo-generator as the research object, the two-dimensional finite element electromagnetic model of stator/rotor and the three-dimensional finite element heat transfer model of rotor were established. The electromagnetic field, temperature field, and stress field of the generator were simulated and analyzed. At the same time, the air gap magnetic field, three-dimensional temperature field, and stress field distribution of the rotor were calculated for EWISC faults in different fault degrees and positions. The results showed that the EWISC fault weakened the air gap magnetic field and caused unbalanced electromagnetic distribution. At the same time, it caused a distortion of the rotor temperature field, resulting in an unbalanced distribution of the temperature field. The stress field was affected by the distortion of temperature field, and the local thermal stress increased but did not exceed the yield limit of the material. Restorable elastic deformation occurred when the rotor was heated, which caused the thermal bending of the rotor. The method adopted in this paper can provide a reference for the calculation of multiphysical field after a generator fault. It is also pointed out that the thermal unbalance influence should not be neglected in the study of generator vibration characteristics.

Detection of Stator Winding Inter-Turn Short Circuit Fault in Induction Motor Using Vibration Signals by MEMS Accelerometer

This paper presents a novel method for detecting stator winding inter-turn short circuit fault in a three-phase induction motor by vibration signature analysis using non-electrical contact type microelectromechanical systems (MEMS) accelerometer. The present work detects inter-turn short circuit by vibration analysis in a three-phase induction motor running under different load conditions. Theoretical analysis of stator winding under inter-turn short circuit condition has been presented. Experimental investigations have been carried out to detect inter-turn short circuit fault by vibration signature analysis using a MEMS accelerometer with three-phase induction motor operating under different conditions. The spectral analysis of motor vibration has been carried out using radix-2 decimation in time fast Fourier transform algorithm. The appearance of particular characteristic frequency components in vibration spectrum indicates stator winding inter-turn short circuit faults. The experimental results are found to closely match with the theoretical values, indicating that MEMS accelerometers can be successfully employed for the detection of stator winding inter-turn short circuit fault in induction motors.

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.

Stator Winding Interturn Short-Circuit Faults Severity Detection Controlled by OW-SVPWM Without CMV of a Five-Phase FTFSCW-IPM

This paper proposed a method to detect different interturn short-circuit fault severity by analyzing zero-sequence current for a new five-phase fault-tolerant fractional-slot concentrated winding interior permanent magnet motor (FTFSCW-IPM). To eliminate the effect of common-mode voltage in single dc power supply application, fault severity analysis is conducted based on an open-end winding (OW) space vector. This new method is verified by simulation and experimental results in a five-phase FTFSCW-IPM OW system.

Detection of Stator Winding Inter-Turn Short Circuit Faults in Permanent Magnet Synchronous Motors and Automatic Classification of Fault Severity via a Pattern Recognition System

In this study, automatic detection of stator winding inter-turn short circuit fault (SWISCFs) in surface-mounted permanent magnet synchronous motors (SPMSMs) and automatic classification of fault severity via a pattern recognition system (PRS) are presented. In the case of a stator short circuit fault, performance losses become an important issue for SPMSMs. To detect stator winding short circuit faults automatically and to estimate the severity of the fault, an artificial neural network (ANN)-based PRS was used. It was found that the amplitude of the third harmonic of the current was the most distinctive characteristic for detecting the short circuit fault ratio of the SPMSM. To validate the proposed method, both simulation results and experimental results are presented.

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.

Detection and Analysis of Stator Winding Inter-Turn Short Circuit Fault in Permanent Magnet Linear Synchronous Motor

A two-dimensional finite element model of PMLSM is build based on the finite element analysis software Magnet to research the diagnosis of stator winding inter-turn short circuit fault in PMLSM. The velocity, thrust, the stator current performance curve are obtained by simulation using Magnet when PMLSM is normal and under different extent inter-turn short circuit fault, the harmonic content of speed and thrust are analyzed using Matlab / Simulink , the conclusion that the thrust of the harmonic content is used as the Permanent Magnet Linear Synchronous Motor (PMLSM) stator inter-turn short circuit fault feature is proposed , which provided a basis for detection of stator winding inter-turn short circuit fault in PMLSM.

Wing Technique: A Novel Approach for the Detection of Stator Winding Inter-Turn Short Circuit and Open Circuit Faults in Three Phase Induction Motors

This paper presents a novel approach based on the loci of instantaneous symmetrical components called "Wing Shape" which requires the measurement of three input stator currents and voltages to diagnose interturn insulation faults in three phase induction motors operating under different loading conditions. In this methodology, the effect of unbalanced supply conditions, constructional imbalances and measurement errors are also investigated. The sizes of the wings determine the loading on the motor and the travel of the wings while their areas determine the degree of severity of the faults. This approach is also applied to detect open circuit faults or single phasing conditions in induction motors. In order to validate this method, experimental results are presented for a 5 hp squirrel cage induction motor. The proposed technique helps improve the reliability, efficiency, and safety of the motor system and industrial plant. It also allows maintenance to be performed in a more efficient manner, since the course of action can be determined based on the type and severity of the fault.

Research on Stator Winding Inter Turn Short-Circuit Faults of Aeronautical Fault-Tolerant Machine Based on Maxwell 2D

Stator winding inter turn short-circuit fault is one of the most common internal faults of fault-tolerant machine, which can disconnect the fault phases and keep operating correctly in the event of a failure. Stator winding short-circuit fault model is established through analysis. Based on finite element method, the high-power density fault-tolerant machine internal magnetic field simulation and analysis is implemented using Maxwell2D and induced voltage frequency spectrum is analyzed by FFT method. The characteristics of stator winding short-circuit faults are summarized, which lay a solid foundation for fault-tolerant machine earlier faults prediction and winding switching.

Modeling of Surface-Mounted Permanent Magnet Synchronous Motors With Stator Winding Interturn Faults

This paper develops and analyzes a parametric model for simulating healthy and faulty surface-mounted permanent magnet synchronous motors. It allows studying the effects of stator winding interturn short-circuit faults. A relevant feature of the developed model is that it deals with spatial harmonics due to a nonsinusoidal rotor permanent magnet configuration. Additionally, the proposed model is valid for studying the behavior of these machines running under nonstationary conditions, including load or speed variations. Stator current spectra obtained from simulations performed by applying the proposed model show a close similitude with experimental results, highlighting the potential of such a model to understand the effects of stator winding failures on the current spectrum and allowing it to carry out an automatic diagnosis of such faults.

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.