A new Wavelet based ground fault protection scheme for turbo generators

Statistical method for fault detection in synchronous generators

Abstract: This paper presents a new methodology to detect faults in synchronous generators. The proposed approach is based on principal component analysis. Principal component analysis is a multivariate statistical technique used for detecting fault transients and characterization of faults. The proposed fault detection scheme is able to distinguish internal and external faults. The proposed scheme will aid in development of an automatic protective relay for the synchronous generators.

A new protection algorithm for synchronous generators using artificial neural networks

Abstract: This paper presents a new protection scheme for synchronous generator using an artificial neural network. The proposed scheme is able to discriminate internal and external faults of synchronous generator, consists of feature extraction using eigenvalues and fault classification using artificial neural networks. The performance of algorithm was tested using artificial neural networks and simulation results show the proposed scheme is able to identify and classify all types of faults of synchronous generator. The proposed approach has the ability to detect the generator winding faults which are close to neutral.

Fault Detection in Synchronous Generators Based on Independent Component Analysis

Abstract: A novel technique for fault detection and classification in the synchronous generator is proposed. In this paper, a new statistical method based on independent component analysis is presented. The proposed fault detection scheme identifies external and internal faults of synchronous generator. This characterization of fault transients will aid in the development of a protection relay for synchronous generator and the proposed method is effective in detecting faults and has great potential in power engineering applications.

Third harmonic differential over current relay based protection system for stator ground fault in synchronous generator

Abstract: In this paper, a new method is proposed for 100% protection against the stator earth fault in synchronous generator. Conventional ground fault protection schemes can be applied to any generator but it covers at most 95% of generator stator length. For ensuring 100% protection of synchronous generator stator winding, conventional ground fault schemes are combined with our proposed third harmonic differential over current protection scheme. Moreover, an investigation into the differences between first harmonic fault current and third harmonic fault current is performed. By using proper simulation model, earth faults are simulated at various distant points from the generator neutral and using this simulations, first harmonic fault current and third harmonic fault current characteristics are properly distinguished. Finally, the threshold current of our proposed differential third harmonic over current relay is selected based on the results of the simulations.

Wind Farm Connected Distribution System Protection Using Wavelet-Alienation Coefficient Technique

Abstract: This paper deals with an algorithm, based on wavelet-Alienation coefficients for protection of wind farm connected distribution network. The proposed algorithm takes the differential current signal of grid node and wind farm coupling node. The Wavelet transform used to extract the approximation coefficients of all the three-phase current signals. Alienation coefficients of each differential phase current obtained over a half cycle is used to identify and categorize the various faults. A modified IEEE13 bus test feeder system used for simulation in MATLAB. Proposed technique tested for detection of all shunt faults at each bus of the distribution system.

Exploring the power of wavelet analysis

Abstract: Wavelets are a recently developed mathematical tool for signal analysis. Informally, a wavelet is a short-term duration wave. Wavelets are used as a kernel function in an integral transform, much in the same way that sines and cosines are used in Fourier analysis or the Walsh functions in Walsh analysis. To date, the primary application of wavelets has been in the areas of signal processing, image compression, subband coding, medical imaging, data compression, seismic studies, denoising data, computer vision and sound synthesis. Here, the authors describe how wavelets may be used in the analysis of power system transients using computer implementation.

A Comparison of 100 Percent Stator Ground Fault Protection Schemes for Generator Stator Windings

Abstract: This paper describes three different schemes for detecting single-phase-to-ground faults in 100% of the generator stator winding. The operating theory, a setting example, and field measurements are provided for each of the three schemes. A chart comparing the significant application characteristics of the three schemes is presented.

Adaptive ground fault protection schemes for turbogenerator based on third harmonic voltages

Abstract: Equivalent circuits based on the actual connection of coil-groups of generators are used to study the characteristics of various generator stator ground fault protection schemes presented in the literature. The evaluation and the comparison of the characteristics of those schemes are given by means of protection coverage-critical resistance curves. Although these schemes are successful in practice, they suffer the disadvantage of low sensitivity, which is strongly related to generator operating conditions. To overcome this disadvantage, two adaptive stator ground fault protection schemes based on digital techniques are developed. Compared to conventional third-harmonic voltage schemes, they can automatically track the change of generator operating conditions before a ground fault occurs. Test results from a digital simulation show that they can keep high sensitivity during all operating conditions. >

Performance of Third Harmonic Ground Fault Protection Schemes for Generator Stator Windings

Abstract: The paper shows how the normally generated third-harmonic voltage can be used to protect the lower ten to twenty percent of generator stator windings against ground faults. A method of determining the applicability of the scheme to a given machine is described which takes into account the design of the generator and its externally connected apparatus. The effects of finite resistence ground faults are also investigated and other advantages of the scheme, such as protection of the neutral, are also highlighted.