This paper presents experimental and theoretical analyses used to establish electrical features that can be utilized as indicators of armature winding, field winding or rectifier diode deterioration in brushless three-phase synchronous generators before the imperfection progresses to become a ground fault. The paper begins with the description of a 5 kVA synchronous generator specifically designed and constructed to allow for simulation of armature winding, field winding or rectifier diode deterioration in a brushless machine. Subsequently, a description of the experimental methodology and the results of experiments are presented. Specific features that can be used as indicators of the deterioration are described and a theoretical basis for them is provided. The proposed features can be obtained continuously during normal generator operation. As such, they can be used as a basis for both winding brushless and brush-fed synchronous generator health monitoring applications.

Condition Monitoring of Brushless Three-Phase Synchronous Generators With Stator Winding or Rotor Circuit Deterioration

This paper describes a digital technique for protecting busbars. The technique uses positive- and negative-sequence models of the power system in a fault-detection algorithm. While phase voltages and currents are used to detect faults, parameters of the power system are not used. An analysis of the performance of the proposed technique during CT saturation and ratio-mismatch conditions is presented. The performance of the technique was investigated for a variety of operating conditions and for several busbar configurations. Data generated by EMTP simulations of model power systems were used in the investigations. The results indicate that the proposed technique is stable during CT saturation and ratio-mismatch conditions.

A busbar protection technique and its performance during CT saturation and CT ratio-mismatch

This paper describes a new artificial neural network (ANN) based digital differential protection scheme for generator stator winding protection. The scheme includes two feedforward neural networks (FNNs). One ANN is used for fault detection and the other is used for internal fault classification. This design uses current samples from the line-side and the neutral-end in addition to samples from the field current. Fundamental and/or second harmonic present in the field current during a fault help the ANN, used for fault detection, to differentiate between generator states (normal, external fault and internal fault states). Results showing the performance of the protection scheme are presented and indicate that it is fast and reliable.

An artificial neural network based digital differential protection scheme for synchronous generator stator winding protection

Summary form only given as follows. This paper describes a digital technique for protecting power transformers. The technique uses positive- and negative-sequence models of the power system in a fault-detection algorithm. While phase voltages and currents at the transformer terminals are used to detect a fault, no information concerning parameters of the transformer and power system is required. The performance of the proposed technique was studied for a variety of operating conditions using data generated by EMTP simulations. The impact of ratio-mismatch and saturation of current transformers on the performance of the technique was also examined. Results indicate that the proposed technique is stable during these conditions.

A power transformer protection technique with stability during current transformer saturation and ratio-mismatch conditions

The design, implementation and testing of a microprocessor-based busbar protection system is presented. The proposed system employs a protection technique that uses the positive- and negative-sequence models of the power system. The system is composed of delta-impedance relays which implement a fault-detection algorithm, based on the developed technique. The algorithm, hardware and software of the relays are described. Performance of the proposed system was checked in the laboratory; the testing procedure and test results are presented.

Microprocessor-based busbar protection system

A digital technique for stator winding protection of synchronous generators

The authors describe the development of an algorithm for detecting internal faults in the windings of synchronous generators. The fault detection algorithm is based on the positive- and negative-sequence models of the synchronous machine. The algorithm uses voltages and currents at the generator terminals to detect the faults. The performance of the proposed algorithm was tested using data recorded from a laboratory generator which was subjected to a variety of internal and external faults. The results indicate that the algorithm effectively detects winding faults. >

B.R. Sunga

Papers

A digital technique for stator winding protection of synchronous generators

A modeling approach for digital protection of synchronous generators