On-line Condition Monitoring, Fault Detection and Diagnosis in Electrical Machines and Power Electronic Converters

The objective of this PhD research is to develop robust, and non-intrusive condition monitoring methods for induction motors fed by closed-loop inverters. The flexible energy forms synthesized by these connected power electronic converters greatly enhance the performance and expand the operating region of induction motors. They also significantly alter the fault behavior of these electric machines and complicate the fault detection and protection. The current state of the art in condition monitoring of power-converter-fed electric machines is underdeveloped as compared to the maturing condition monitoring techniques for grid-connected electric machines. This dissertation first investigates the stator turn-to-turn fault modelling for induction motors (IM) fed by a grid directly. A novel and more meaningful model of the motor itself was developed and a comprehensive study of the closed-loop inverter drives was conducted. A direct torque control (DTC) method was selected for controlling IM’s electromagnetic torque and stator flux-linkage amplitude in industrial applications. Additionally, a new driver based on DTC rules, predictive control theory and fuzzy logic inference system for the IM was developed. This novel controller improves the performance of the torque control on the IM as it reduces most of the disadvantages of the classical and predictive DTC drivers. An analytical investigation of the impacts of the stator inter-turn short-circuit of the machine in the controller and its reaction was performed. This research sets a based knowledge and clear foundations of the events happening inside the IM and internally in the DTC when the machine is damaged by a turn fault in the stator. This dissertation also develops a technique for the health monitoring of the induction machine under stator turn failure. The developed technique was based on the monitoring of the off-diagonal term of the sequence component impedance matrix. Its advantages are that it is independent of the IM parameters, it is immune to the sensors’ errors, it requires a small learning stage, compared with NN, and it is not intrusive, robust and online. The research developed in this dissertation represents a significant advance that can be utilized in fault detection and condition monitoring in industrial applications, transportation electrification as well as the utilization of renewable energy microgrids. To conclude, this PhD research focuses on the development of condition monitoring techniques, modelling, and insightful analyses of a specific type of electric machine system. The fundamental ideas behind the proposed condition monitoring technique, model and analysis are quite universal and appeals to a much wider variety of electric machines connected to power electronic converters or drivers. To sum up, this PhD research has a broad beneficial impact on a wide spectrum of power-converter-fed electric machines and is thus of practical importance

Power Converter of Electric Machines, Renewable Energy Systems, and Transportation

Power converters and electric machines represent essential components in all fields of electrical engineering. In fact, we are heading towards a future where energy will be more and more electrical: electrical vehicles, electrical motors, renewables, storage systems are now widespread. The ongoing energy transition poses new challenges for interfacing and integrating different power systems. The constraints of space, weight, reliability, performance, and autonomy for the electric system have increased the attention of scientific research in order to find more and more appropriate technological solutions. In this context, power converters and electric machines assume a key role in enabling higher performance of electrical power conversion. Consequently, the design and control of power converters and electric machines shall be developed accordingly to the requirements of the specific application, thus leading to more specialized solutions, with the aim of enhancing the reliability, fault tolerance, and flexibility of the next generation power systems

Modelling of ground penetrating radar backscatter for water pipeline leakage detection

Subsurface water leaks not only waste precious natural resources, but also create substantial damages to the transportation system and structures within urban and suburban environments. While many geophysical techniques have been suggested for detecting water leakage including ground-penetrating radar (GPR), acoustic devices, gas sampling devices and pressure wave detectors, there is no ideal solution for it. Nonetheless, GPR, a non-destructive geophysical technique which uses high frequency electromagnetic waves to acquire subsurface information has been regularly utilized as GPR responds to the changes in electrical properties, which is a function of soil and rock material, and moisture content. To evaluate the feasibility of GPR in detecting water pipe leakage, a finite-difference time-domain (FDTD) numerical modelling is conducted together with water pipe leakage detection fieldwork and experimental test. To properly design the features of the imaging approach, and test its capabilities in controlled conditions, the synthetic data was generated in a two dimensional FDTD forward modelling solver capable of accurately simulating real world GPR scenarios. Different types of simulate conditions involving sizes of leakage area, frequencies (250 MHz and 700 MHz), pipe materials (AC, DI, PVC, MS and HDPE) and pipe sizes (100mm, 200mm and 300mm) were conducted. For the fieldwork, case studies were carried out using GPR scanning equipment (Detector Duo) to validate FDTD numerical model. For the experimental test, Detector Duo was used to collect data on top of District Metering Areas testbed. More understanding regarding the signature of leakage was gained in radargram. Compared to a distinct hyperbola or line as shown in radargram of intact pipes, the leakage zone is disturbed by the wave reflection caused by saturated soil. Numerically simulated results seem to be in agreement with the case studies and experimental results. The signature of pipe and leakage are clearly visible in the simulated radargram compared with those in the case studies and experimental radargram. Therefore, GPR survey seems promising as an efficient non-destructive geophysical technique for leakage detection approach. This finding is useful to provide protocols for GPR profile interpretation, particularly in underground water pipe leakage detection

The analytical and artificial intelligence methods to investigate the effects of aperture dimension ratio on electrical shielding effectiveness

This paper presents that the effect of single aperture size of metallic enclosure on electrical shielding effectiveness (ESE) at 0 – 1 GHz frequency range has been investigated by using both Robinson’s analytical formulation and artificial neural networks (ANN) methods that are multilayer perceptron (MLP) networks and a radial basis function neural network (RBFNN). All results including measurement have been compared each other in terms of aperture geometry of metallic enclosure. The geometry of single aperture varies from square to rectangular shape while the open area of aperture is fixed. It has been observed that network structure of MLP 3-40-1 in modeling with ANN modeled with fewer neurons in the sense of overlapping of faults and data and modeled accordingly. In contrast, the RBFNN 3-150-1 is the other detection that the network structure is modeled with more neurons and more. It can be seen from the same network-structured MLP and RBFNN that the MLP modeled better. In this paper, the impact of dimension of rectangular aperture on shielding performance by using RBFNN and MLP network model with ANN has been studied, as a novelty

Faults Detection for Power Systems

Non

Comparison of Switched Reluctance Motor and Double Stator Switched Reluctance Motor

This thesis is concerned with the design and analysis of Switched Reluctance Motor (SRM) and its improved structure Double Stator Switched Reluctance Motor (DSSRM). Three configurations of SRM viz. Inner Stator, Outer stator and Double Stator are designed and simulated in ANSYS Maxwell Suite. Design parameters are chosen by aiming optimum performance of motor after literature review and analytical study of the motor. SRM is not a line start machine, so power converter circuit is required to excite the motor. Without proper switching of current, desired torque is not obtained in SRM. The converter circuit and switching unit is built in Maxwell Circuit Editor Tools. Both magnetostatics and transient analysis is performed to investigate motion torque, torque ripple, normal force and radial force. A good comprehensive comparison of three different types of SRMs based on their torque profile and force densities is presented. Simulation performed verified better performance of DSSRM

Comparison of Switched Reluctance Motor and Double Stator Switched Reluctance Motor

This thesis is concerned with the design and analysis of Switched Reluctance Motor (SRM) and its improved structure Double Stator Switched Reluctance Motor (DSSRM). Three configurations of SRM viz. Inner Stator, Outer stator and Double Stator are designed and simulated in ANSYS Maxwell Suite. Design parameters are chosen by aiming optimum performance of motor after literature review and analytical study of the motor. SRM is not a line start machine, so power converter circuit is required to excite the motor. Without proper switching of current, desired torque is not obtained in SRM. The converter circuit and switching unit is built in Maxwell Circuit Editor Tools. Both magnetostatics and transient analysis is performed to investigate motion torque, torque ripple, normal force and radial force. A good comprehensive comparison of three different types of SRMs based on their torque profile and force densities is presented. Simulation performed verified better performance of DSSRM

Recent Progress in Electrical Generators for Oceanic Wave Energy Conversion

Oceanic wave energy extraction through electrical generator is one of the most interesting topics in the field of power engineering. Almost all the existing relevant review paper focus on electrical generator with the working principle of electromagnetic induction or piezoelectric or triboelectric effect. In this paper, all the existing types (based on principle of operation) of electrical generator used for wave power harvesting are discussed. This paper not only covers recent progress in electrical power generation by electro-magnetic induction, piezoelectric generator, and electrostatic induction, but also presents critical comparative review as well where suitable use and weakness of each type of generators are discussed. Moreover, the application of advanced magnetic core, winding, and permanent magnets are discussed with extensive explanation which are not focused in the existing reviews. Various new constructional features of the electrical generators such as split translator flux switching, two-point absorber, triangular coil, dual port linear generator, piezoelectric, triboelectric nanogenerator, etc. are highlighted with principles of operation. It also includes emerging human intervened optimization method for determining optimum shape of generator and cooling system which is necessary to prevent demagnetization of the permanent magnet. Finally, the way of supply the generated electrical power form the generator to load/grid is thoroughly described in a separate section that would be obvious for successful operation. The comparison among all types of generators in terms of output voltage, current, scale of power production, power-frequency characteristics, power density, cascading, and approaches are tabulated in this paper