Turn-to-turn fault protection technique for synchronous machines without additional voltage transformers

This paper presents a novel protection technique for the detection of inter-turn faults in synchronous machines. It is based on the calculation of voltage in the stator windings from the usual phases and neutral voltage, typically available in allgenerator protection relays. The existing turn-to-turn protection mechanisms require additional voltage transformers. The main contribution of this technique is that it can be implemented without using any additional voltage transformers. Thistechnique has been successfully tested in a special synchronous machine with taps in the stator windings, where turn-to-turn faults have been created

Detection of inter-turn faults in multi-phase ferrite-PM assisted synchronous reluctance machine

Inter-turn winding faults in five-phase ferrite-permanent magnet-assisted synchronous reluctance motors (fPMa-SynRMs) can lead to catastrophic consequences if not detected in a timely manner, since they can quickly progress into more severe short-circuit faults, such as coil-to-coil, phase-to-ground or phase-to-phase faults. This paper analyzes the feasibility of detecting such harmful faults in their early stage, with only one short-circuited turn, since there is a lack of works related to this topic in multi-phase fPMa-SynRMs. Two methods are tested for this purpose, the analysis of the spectral content of the zero-sequence voltage component (ZSVC) and the analysis of the stator current spectra, also known as motor current signature analysis (MCSA), which is a well-known fault diagnosis method. This paper compares the performance and sensitivity of both methods under different operating conditions. It is proven that inter-turn faults can be detected in the early stage, with the ZSVC providing more sensitivity than the MCSA method. It is also proven that the working conditions have little effect on the sensitivity of both methods. To conclude, this paper proposes two inter-turn fault indicators and the threshold values to detect such faults in the early stage, which are calculated from the spectral information of the ZSVC and the line currentsPeer ReviewedPostprint (published version

Transformers on-load exciting current Park`s vector approach as a tool for winding faults diagnostics

This paper presents the development of a new approach for diagnosing the occurrence of inter-turn short-circuits in the windings of three-phase transformers, which is based on the on-line monitoring of the on-load exciting current Park's Vector patterns. Experimental and simulated results demonstrate the effectiveness of the proposed technique for detecting winding inter-turn insulation faults in operating three-phase transformers

On-line diagnostics of transformer winding insulation failures, by Park's Vector Approach

This paper presents a non-invasive approach for diagnosing winding insulation failures in three-phase transformers, which is based on the on-line monitoring of the primary and secondary current Park's Vector. Experimental and simulated results demonstrate the effectiveness of the proposed technique, for detecting winding inter-turn insulation faults in operating three-phase transformers

Simulation of electrical faults of three phase induction motor drive system

The title of this project is Simulation of electrical faults of three phase induction motor drive system. Induction motor or asynchronous motor is a type of alternating current motor where power is supplied to the rotor by means of electromagnetic induction. Induction motor is now the preferred choice for industrial motor due to their rugged construction, absence of brushes (which are required in most DC motors) and the ability to control the speed of motor. The faults that can occur in the three-phase induction motor and its driver can be divided into two parts; internal and external faults. The internal fault of induction motors account for the proportion almost more than 70% of induction motor failures. This project will cover and study a few type of internal and external faults, which is the stator inter-turn short circuit, unbalanced voltage supply and the single phase open circuit fault. The study of induction motor is crucial and important so that the lifespan of the motor can be prolonged. In this project MATLAB SIMULINK is used to simulate the induction motor faults and analyze the condition. The simulation file is then compiled along with a GUI to simplify the overall process and improves the user friendliness to users

On-line diagnostics of transformer winding insulation failures, by Park`s vector approach

This paper presents a non-invasive approach for diagnosing winding insulation failures in three-phase transformers, which is based on the on-line monitoring of the primary and secondary current Park's Vector. Experimental and simulated results demonstrate the effectiveness of the proposed technique, for detecting winding inter-turn insulation faults in operating three-phase transformers

Condition monitoring approach for permanent magnet synchronous motor drives based on the INFORM method

This paper proposes a monitoring scheme based on saliency tracking to assess the health condition of PMSM drives operating under non stationary conditions. The evaluated scheme is based on the INFORM methodology, which is associated to the accurate sensorless control of PM drives without zero speed limitation. The result is a monitoring scheme that is able to detect faults that would be very difficult to evaluate under nonstationary conditions. A relevant aspect of the proposed scheme is that it remains valid for full speed range, and can be used for standstill operation. Additionally, the approach is insensitive to the inverter nonlinearities which enhance the detection capabilities further respect to similar topologies. In this work the proposed approach is evaluated numerically and experimentally in the presence of incipient winding faults and inter-turn short circuits in a PM conventional drive. The obtained results show quick response and excellent detection capabilities not only in the detection of faults, but to determine their magnitude which is vital to avoid further degradation

Investigation into Fault Tolerant Capability of a Triple Redundant PMA SynRM Drive

Fault tolerant machine drives are being favored in safety critical applications, thus they are being actively investigated. However, most of the solutions address the winding or switch open circuit only, which is insufficient since intra-phase and inter-phase turn short circuits are more likely in the machine drives as a result of insulation degradation, and the consequences are usually catastrophic. Magnets and capacitor may also fail and cause damage during operation. All these faults should be properly addressed in fault tolerant machine drives for safety critical applications. Hence, a triple redundant, 9 phase (3x3phase) permanent magnet assisted synchronous reluctance machine (PMA SynRM) drive is presented by investigating the fault tolerances against various faults. The different fault behaviors are evaluated and the corresponding fault tolerant capabilities are analyzed. The machine fault tolerance is examined on a 35kW prototype drive. Both the analysis and experimental tests demonstrate that the machine drive exhibits excellent fault tolerant capability under most common types of faults, including the intra-phase and inter-phase short circuit, uncontrolled rectification, demagnetization and DC capacitor fault

Improved transient simulation of salient-pole synchronous generators with internal and ground faults in the stator winding

An improved model for simulating the transient behavior of salient-pole synchronous generators with internal and ground faults in the stator winding is established using the multi-loop circuit method. The model caters for faults under different ground conditions for the neutral, and accounts for the distributed capacitances of the windings to ground. Predictions from the model are validated by experiments, and it is shown that the model accurately predicts the voltage and current waveforms under fault conditions. Hence, it can be used to analyze important features of faults and to design appropriate protection schemes

Stator turn fault detection by 2nd harmonic in instantaneous power for a triple redundant fault-tolerant PM drive

Fast and reliable detection of stator faults is of key importance for fail-safe and fault tolerant machine drives in order to immediately trigger appropriate fault mitigation actions. The paper presents a detailed analytical and experimental analysis of the behavior of a closed loop controlled permanent magnet machine drive under inter-turn fault conditions. It is shown that significant 2nd harmonic components in the dq voltages, currents, instantaneous active power (IAP) and reactive power (IRP) are generated during turn fault conditions. The analyses further show that the increase of the 2nd harmonic in IAP and IRP during fault conditions is comparatively higher than that of voltage and current, making them ideal candidates as turn fault indicators. A turn fault detection technique based on 2nd harmonic in IAP and IRP is implemented and demonstrated for a triple redundant, fault tolerant permanent magnet assisted synchronous reluctance machine (PMA SynRM) drive. The effectiveness of the proposed detection technique over the whole operation region is assessed, demonstrating fast and reliable detection over most of the operating region under both motoring and generating mode