Stator Ground Fault Protection Schemes Research Articles

Adaptive 100% Injection-Based Generator Stator Ground Fault Protection With Real-Time Fault Location Capability

The paper presents a novel adaptive stator ground fault protection scheme with fault location capability for high-impedance grounded synchronous generators. The protection scheme uses already available neutral grounding signals in the existing subharmonic injection protection to obtain a Kalman adaptive filter (KAF) for real-time stator insulation parameter estimation. The KAF estimator yields a method of continuous tracking of stator insulation condition during healthy operations. This information is then used for real-time stator ground fault detection as well as fault location. The effectiveness of the proposed method is verified using extensive experiments performed on a lab-scale unit-connected generating station.

Modeling and Experimental Verification of a 100% Stator Ground Fault Protection Based on Adaptive Third-Harmonic Differential Voltage Scheme for Synchronous Generators

In this paper, a novel adaptive stator-ground fault protection scheme based on third-harmonic differential voltages is implemented on a lab scale synchronous generator. The lab scale generator is used to emulate the fault characteristics of industrial generators along the stator windings. Simulations based on finite element analysis methods were used to design and tune the laboratory testbed. Experimental results prove the expected fault characteristics as well as fault detection capability of the adaptive stator-ground fault protection scheme.

Wavelet ANN Based Stator Ground Fault Protection Scheme for Turbo Generators

This article proposes a protection scheme for turbo generators to detect stator ground faults in particular closer to neutral. The scheme considers total generated voltage of the machine and makes use of wavelet multi-resolution analysis. A fault index is defined in terms of peak and valley values of the highest-level wavelet decomposition, which is compared with a threshold value to discriminate from other transients, like sudden unbalance, in load. To identify the faulty coil, an ANN employing back propagation algorithm is used with the lowest level wavelet coefficients as inputs. The results of digital simulation are presented for different fault impedances and fault locations.

Wavelet-based directional stator ground fault protection for generator

This paper introduces a wavelet-based stator ground fault protection scheme with selectivity for generator. It is found that the WT results of the measured zero sequence current at the terminals, zero sequence voltages at the neutral and the terminals of a fault generator, especially the modulus maxima, contain important information. It can be used to discriminate the generator stator ground fault. By applying the zero sequence current, the proposed scheme can detect if the fault is in the internal generator or out of the generator. The effectiveness of the proposed scheme was verified both in the experiment and in the field. Investigation results show that the scheme can detect the ground fault with high sensitivity and selectivity during all operating conditions.

Wavelet-based ground fault protection scheme for generator stator winding

Abstract A new stator ground fault protection scheme is introduced in this paper. It is based on wavelet transform, particularly the multiresolution analysis (MRA) technique. The effectiveness of the proposed scheme was verified both in the experiment and in the field. Investigation results show that the scheme can detect the ground fault with high sensitivity and selectivity during all operating conditions.

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

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.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

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

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

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

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.