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A new approach to synchronous generator internal fault simulation using combined winding function theory and direct phase quantities
Abstract
In this paper, a new method which combines the direct phase
quantifies approach with the winding function theory is described. With
this approach, the problem of effectively modeling the asymmetries in
the stator and rotor with the concomitant effects of space harmonics is
overcome. The paper also gives details of machine models under normal
conditions and under various fault conditions, namely single phase to
ground, double phase to ground and three phase to ground faults at
different fault locations. Some typical waveforms are presented with
respect to a 6 MVA, 6.6 kV synchronous generator
... PMSM modeling is the first step in the development of diagnostic systems [4], [5]. Models show a complex relationship between parameters, accurate identification of a fault is very difficult. ...
In the transition to automated and automatic manufacturing an urgent problem is to increase the reliability of mobile robots (MR) and their drives, creation of devices to monitor the technical characteristics of MR, diagnose and predict the remaining resource. Inspite of the high relevance of the diagnosing MR drives problem, there are no generally accepted methodology for diagnosing MR drives, criteria for selecting methods, parameters and volumes of diagnostics at present. An unsolved problem, related to the diagnosis of MR drives and the prediction of their residual life remains, is the development of methods that allow to carry out of automatic complex multiparametric diagnostics and prediction of the residual life using artificial intelligence methods. Effective fault detection and diagnosis can improve the reliability of the MR drive and avoid costly maintenance. In this paper a fault detection scheme for synchronous motors with permanent magnets based on a fuzzy system is proposed. The sequence current components (positive and negative sequence currents) are used as fault indicators and are set as input to the fuzzy fault detector. The expediency of the proposed scheme for determining of various types of faults for a synchronous motor with permanent magnets under various operating conditions is simulated using the SimInTech software.
... The PDM can deal with the saturation conditions, as described in Ref. [17]. Some have presented a modified winding function approach (MWFA), which combines the WFA and PDM model for detecting the phase to ground faults [9,18,19]. The MWFA, as an extended version of the WFA, is used in a non-uniform air-gap machine [20]. ...
Synchronous generator (SG) plays a vital and critical role in the power system by supplying electric power to consumers. Various faults in SGs can cause some catastrophic events such as power disruption or blackout. These faults can be classified into two electrical and mechanical faults. Short circuit in stator windings and field winding are electrical fault while bearing, static/dynamic eccentricity, and broken damper bars faults are mechanical one. Unlike the induction machines, there are no much researches in SGs condition monitoring owing to its complex behaviour against the faults. Herein, the SG modelling approaches are presented briefly to elaborate shortcoming and challenging issues in the modelling, and then a comprehensive review of various electrical and mechanical fault detection methods is presented.
... Internal faults create an imbalance in the winding of the machine. This imbalance in windings will lead to an imbalance in the mutual and magnetizing inductances of the machine [23]. Hence, the balance of the generator terminal voltage will be altered, leading to an increase in neutral voltage. ...
In this paper, a comprehensive mathematical model for synchronous generators under stator winding faults near the star point using the Modified Winding Function is described. The model includes space harmonics and their effects on windings inductances. The model is verified using electromagnetic analysis through 2D Finite Element Analysis simulation and experimental testing. The results prove the accuracy of the proposed mathematical model in reflecting the features of synchronous generators under stator windings ground faults in different parts of the winding and specifically near the star point. The developed modeling technique can be used for designing protections schemes for the very challenging 100% stator winding ground fault protection. The model enables protection designers to obtain rich set of data for protection relays designing and testing.
... This method uses the main component of zero sequence voltage to detect PGFs in 95% of the stator winding and the related third harmonic component for fault detection in the remnant winding (5%) in the neutral point vicinity. A combination of winding function theory and direct phase quantities is used in [17][18][19] to simulate the internal faults in the synchronous machines. In this simulation, only the odd space harmonics are considered to calculate the winding inductances while the faulty windings can produce some harmonics and even fractional sub-harmonics. ...
In this paper, a novel method is presented for detection and classification of the faulty
phase/region in the stator winding of synchronous generators on the basis of the resulting harmonic components that appear in the terminal voltage waveforms. Analytical results obtained through Decision Tree (DT) show that the internal faults are not only detectable but also they can be classified and the related region can be estimated. Therefore, this scheme can be used to protect the synchronous generators against the various internal faults. Fuji technical documents and data sheets for an actual salient pole synchronous generator (one unit of an Iran’s hydroelectric power plants) are used for the
modeling. Simulations in Maxwell software environment are presented. All the related parameters, such as B-H curve, unsymmetrical air gap and pole saliency, slot-teeth effect, and other actual parameters, are considered to obtain a comprehensive model to generate acceptable terminal voltage waveforms without any simplification.
... In [8][10] [14], the WFA with PD model is utilized to model the stator winding phase to ground faults. However, the inter-turn short circuit within a stator phase winding coil is not explored. ...
... The combined winding function theory and direct phase quantities to simulate internal faults in the synchronous machines were used in [17][18][19], where only the odd space harmonics are included in the calculation of the winding inductances, while the faulty windings can produce some harmonics and even fractional sub-harmonics. ...
In this paper, a novel method is presented to detect and classify turn-turn faults (TTF) in stator winding of the synchronous generators on the basis of resulting harmonics contents in the terminal voltage waveforms. Analytical results by using Decision Tree (DT) show that this algorithm is practicable using only the first harmonic of residual voltage and only two harmonic component values. Simulations in Maxwell software are done using Fuji's technical documents and data sheets of an actual salient pole synchronous generator (one unit of an Iran's hydroelectric power plants) and all of related parameters (such as B-H curve, unsymmetrical air gap and pole saliency, slot-teeth effect, and so on) are considered to obtain a comprehensive model, without any simplifier assumption.
... A generalized air-gap inverse function for any type of PM machine can be expressed as the Fourier series form, shown in (8) where ...
As the magnets are embedded in a rotor for the interior permanent magnet (IPM) motor, the distribution of the armature reaction magnetic field is different from that of the surface permanent magnet motor (SPM) type. Various methods have been used for the magnetic field solution, including analytical methods based on the winding function and the Laplacian-Poisson equation. However, in the IPM motor, the boundary condition is too complicated for using the Laplacian-Poisson equation. What is more, the equivalent air-gap inverse function presented in literature is not suitable for the IPM motor. A new armature reaction magnetic field model is proposed for the IPM motor, considering the effect of the embedded magnet in the rotor, which is named a pole-cap effect in this paper. The proposed model is derived from the winding function theory, and the rotor magnetic motive force (MMF) function is employed to model the so-called pole-cap effect. The proposed model is used to predict the armature reaction field under a different type of stator MMF, such as different orientation of the excitation current as well as various MMF wavelengths. The calculation result is validated by the finite element analysis (FEA) and shows remarkable advantages over the traditional method. The new model proposed in the paper is quite useful for evaluating various IPM motor performances in an accurate and time-effective manner, such as inductance, stator core losses, and magnet eddy current losses. Complete demonstration of the method to calculate the aforementioned performance indices will be presented in a separate paper, and inductance calculation of a primitive winding is given as an example at the end of this paper.
... The same has been used in the analysis of air gap eccentricity in the synchronous machines Al-Nuaim, 1998, 1999;Tabatabaei et al., 2004). The combined winding function theory and direct phase quantities has been used for simulating the internal faults in the synchronous machines (Jiang et al., 1999). The distribution factor and the pitch factor are taken into account for calculation of inductances. ...
When an internal fault occurs in a synchronous generator, the symmetry between the parallel paths of the winding is broken and different currents flow in them, due to unsymmetrical magnetic linkage between the stator windings. The aim of this paper is to present a simulation model to investigate the effect of internal fault on the parallel path currents of a large synchronous generator using direct phase quantities. This model is based on a modified winding function approach where the machine inductances are calculated directly from the machine winding distribution using machine electrical parameters instead of the geometrical ones. The simulation results for different cases of internal faults in salient-pole and non-salient-pole synchronous machines have been obtained. Salient-pole synchronous generator has wave winding distribution while the non-salient-pole generator has lap winding arrangement. Due to different stator winding arrangements, the two machines have been simulated individually. By using the simulated fault data, a suitable numerical protection scheme for synchronous generators can be developed.
... This approach was used by Toliyat and Al-Nuaim [11,12] in the analysis of air gap eccentricity in synchronous machines. Jiang et al. [13] used the combined winding function theory and direct phase quantities for simulating internal faults in synchronous machines. The distribution factor and the pitch factor are taken into account for the calculation of inductances. ...
When an internal fault occurs in the lap-connected windings of turbogenerators, the symmetry between the parallel windings is broken, and different currents then flow because unsymmetrical magnetic linkage exists between the stator windings. The aim of this article is to present a real-time simulation model to investigate the internal fault currents in large turbogenerators with lap windings. This model is based on a modified winding function approach, where the machine inductances are calculated directly from the machine winding distribution. The calculation of the machine inductances are made easier by the use of machine electrical parameters instead of geometrical parameters. The simulation results have been obtained for different cases of internal faults. By using simulated internal fault data, a suitable numerical protection scheme for turbogenerators can be developed.
... The same approach was used in the analysis of air gap eccentricity in the synchronous machines [12][13][14]. The combined winding function theory and direct phase quantities for simulating the internal faults in the synchronous machines wave used in [15]. The distribution factor and the pitch factor are taken into account for the calculation of inductances. ...
When an internal fault occurs in the wave-connected windings of salient-pole synchronous generators, the symmetry between the parallel windings is broken, and different currents flow in them since unsymmetrical magnetic linkage exists between the stator windings. The aim of this article is to present a model to investigate the internal fault currents in large hydrogenerators with wave windings. This model is based on a modified winding function approach, where the machine inductances are calculated directly from the machine winding distribution, and the space harmonics produced by them are also taken into account. The calculation of the machine inductances are made easier by the use of machine electrical parameters instead of geometrical parameters. The fast Fourier transform analysis of the simulated results has been tabulated for different cases of internal faults. By using the simulated internal fault data, suitable numerical protection schemes for hydrogenerators can be developed.
The research of aircraft generator stator winding faults has great significance to the generator protection design, and the conclusion of the research can be further used to provide a reference for aircraft maintenance decision. In this paper, the inductance parameters of the aircraft generator were calculated at the beginning based on the air-gap permeance method. Then the aircraft generator model with and without stator winding internal fault were built according to the multi-loop method. As two typical fault scenarios of the aircraft generator, inter-turn short circuit and inter-phase short circuit were introduced into the simulation model. And the simulation results show that the excessive short line current has a significant impact on the performance of the motor, which proves that the protection device is necessary for the generator. In addition, the harmonic distribution of the fault current was compared with the case without fault injected, which leads to the observation that the stator current contained more odd harmonics, and the excitation current contained more even harmonics. What's more, such harmonic analysis can provide a theoretical basis for fault diagnosis research.
The turn-to-turn short circuit (TTSC) fault is one of the most common faults in Brushless Synchronous Generator (BLSG). The robust TTSC fault detection, diagnosis and protection techniques require better understanding of the BLSG behaviour during such conditions. This paper presents an improved mathematical model of the main generator in BLSG with TTSC on a stator phase windings. In the proposed BLSG model, the performance under high degree of TTSC fault is improved by combining the d-q model approach and Winding Function Approach (WFA). The d-q model approach is used to keep the model simple for the development of online model based condition monitoring, and the WFA is used to improve the accuracy of the model under TTSC fault condition. The WFA is also used to consider the saturation effect in the model to improve the model accuracy under high degree TTSC fault condition. The verification results showed that the developed BLSG model is able to provide accurate and consistence performance under wider range of TTSC fault in the stator windings.
Upon occurrence of an internal fault on the permanent magnet synchronous machine (PMSM), the topology of the stator is amended causing structural imbalances due to the change of the connection within the windings. In this work, a state model of internal faults of the PMSM is developed. This model is in the (abc) reference frame. The modeling approach is based on the assumption that each stator phase is replaced by two major and minor sub-windings. This model is used subsequently in the residual generation for diagnosis. The fault indicators are obtained by the projection in parity space and estimated using the Luenberger observer. A scenario of fault inter-turn by the short-circuit occurring between phase (a and b) is validated by simulation.
This paper analyzes the way the different number of short-circuited turns during an inter-turn stator fault affects the functional behavior of a salient pole synchronous machine, while this is connected to an infinite bus. In order to achieve more accurate results, two subcases have been examined. In the first one, different number of turns belonging to the same phase is short-circuited, while in the second case the short-circuited turns belong to different phases; nevertheless, their respective number is almost the same. The geometry of the stator winding couldn't provide us with the possibility to simulate the exact same number of short-circuited turns resulting significant differences to both quantitative and qualitative magnitudes.
When an internal fault occurs in the wave-connected windings of salient-pole synchronous generators, the symmetry between the parallel windings is broken, and different currents flow in them since unsymmetrical magnetic linkage exists between the stator windings. The aim of this article is to present a model to investigate the internal fault currents in large hydro generators with wave windings. This model is based on a modified winding function approach, where the machine inductances are calculated directly from the machine winding distribution, and the space harmonics produced by them are also taken into account. By using the simulated internal fault data, suitable numerical protection schemes for hydro generators can be developed.
This paper presents a synchronous machine model for transient system analysis with trapezoidal and Euler methods. The model uses phase coordinates for stator windings coupled with excitation and damper windings. The phase representation allows the integration of synchronous machines parameters in the power system network Y<sub>BUS</sub> matrix. Such matrix allows the simultaneous solution of the machines and the network nodal equations in the time domain. Non linear phenomenon such as saturation effects can also be incorporated and require a few additional iterations. Simulation time can be reduced further for large systems by using decoupled resolution and prediction techniques on the machine current
Considering the space harmonics caused by the faulted windings, a simulation model of internal faults in salient pole synchronous machines is proposed in this paper. The model is based on the winding function approach, which makes no assumption for sinusoidal symmetrical distribution of the machine windings. A new method of calculation of synchronous machine inductances is presented, in which the space harmonics produced by the windings are readily taken into account. Simulation results for internal faults on the stator windings of a generator at no load and at load are compared with experimental results to verify the accuracy of the proposed model.
Internal stator winding faults in salient-pole synchronous
machines can cause serious damage to a machine and the system to which
it is connected. Thus, it is highly desirable to be able to accurately
model their transient behaviour and to predict the resulting currents
and voltages in order to develop appropriate protection schemes,
particularly for high power machines. Based on the multi-loop circuit
method, a general mathematical model for a salient-pole synchronous
machine with internal faults is established, and subsequently employed
to simulate both the steady-state and transient behaviour for three
different types of internal fault. Predicted results are validated by
experimental measurements
A synchronous machine internal faults model based on the actual winding arrangement is described in this paper. Based on the winding function approach, the machine inductances are calculated directly from the machine winding distribution, thereby the space harmonics produced by the machine windings are readily taken into account. Moreover, the calculation of the machine inductances is made easier by the use of the machine electrical parameters instead of the geometrical ones. Simulation results for internal faults on a laboratory generator are compared with experimental results to verify the accuracy of the proposed model
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