An experience of modularity through design

We aim to utilise the experiences of a marine industry-based design team to determine the need for research into a modular design methodology in an industrial environment. In order to achieve this we couple the outcome of a current design project with the findings of a recent literature survey with the objectives of firstly, clarifying why a methodology is required and, secondly, defining the key elements which the methodology would have to realise or address. The potential benefits of modularity have long been recognised in the shipbuilding industry. Many shipbuilders adopt a 'module' approach to ship construction whereby the ship structure is separated into a number of large structural 'blocks' to ease manufacture and manoeuvrability during construction. However, as understanding of the capabilities of modularity as a design tool develops there is increased interest in capitalising on the differing life phase benefits of modularity such as reduced design costs and time, increased ease of maintenance, upgrade, re-use, redesign and standardisation across individual products and product families. This is especially pertinent in naval shipbuilding where the maintenance of a class of ship requires that all previously designed ships in that class must be of similar outfitting and must be able to interface with the new ship, in terms of propulsion, weapons, communications and electronics, and thus often require some form of retrofit. Therefore, many shipbuilders are moving from viewing modularity as a purely 'manufacturing' principle to a design centred principle. However, as noted by Chang and Ward 'none of the design theories or tools in the mechanical world serves as an articulate procedure for designers to follow in practising modular design'. Thus, despite the identification of a need to introduce modular principles at an earlier stage than detail design and construction, there is little aid in the form of tools, techniques and methodologies for designers in practice

Coupling of electromagnetic waves into wires: experiments and simulations

Electromagnetic Compatibility (EMC) problems may occur in many environments. This Thesis considers a particular sub-set of coupling within shielded enclosures. The actual systems studied are the coupling between a dipole and either one or two rods in a screened room and the effect of a cavity and apertures on a signal travelling along a wire. Experiments are described for the screened room which investigate the repeatability of the measurements and the effects of two closely spaced conductors on the coupling results. The cavity experiments also consider the repeatability of the measurements and the effects of the apertures. Transmission-Line Modelling (TLM) is compared with some other popular modelling methods and generally described. It is applied to the modelling of the experimental systems already discussed. An inherent error associated with the modelling of wires in TLM, manifesting itself as an apparent decrease in the resonant frequency of a wire-like structure, is investigated. The source of the error is deduced and a method of minimising it is proposed. The experimental results are applied to the validation of TLM, and its error correction. Very good comparisons between the experiments and simulations are reported. Correlelograms are investigated as a method of comparing the modelled and experimental results

Coupling of electromagnetic waves into wires: experiments and simulations

Electromagnetic Compatibility (EMC) problems may occur in many environments. This Thesis considers a particular sub-set of coupling within shielded enclosures. The actual systems studied are the coupling between a dipole and either one or two rods in a screened room and the effect of a cavity and apertures on a signal travelling along a wire. Experiments are described for the screened room which investigate the repeatability of the measurements and the effects of two closely spaced conductors on the coupling results. The cavity experiments also consider the repeatability of the measurements and the effects of the apertures. Transmission-Line Modelling (TLM) is compared with some other popular modelling methods and generally described. It is applied to the modelling of the experimental systems already discussed. An inherent error associated with the modelling of wires in TLM, manifesting itself as an apparent decrease in the resonant frequency of a wire-like structure, is investigated. The source of the error is deduced and a method of minimising it is proposed. The experimental results are applied to the validation of TLM, and its error correction. Very good comparisons between the experiments and simulations are reported. Correlelograms are investigated as a method of comparing the modelled and experimental results

Factors influencing the successful validation of transient phenomenon modelling

An increased requirement for validation of computational electromagnetic simulation and modelling through the publication of IEEE Standard 1597.1 brings to light some interesting issues surrounding the validation of transients. The structure of a transient event has three particular regions of interest that can have an influence on the results, of which only two are generally well defined. These are the initial quiescent phase from t = 0 to the transient event; the transient event itself up to the point where the energy has fallen to a predefined limit, and the post-transient phase where residual energy is still present in the system. This latter region is generally ill-defined and changes the way that a validation comparison should be made, from, for example a frequency domain coupling study where the region of interest is usually well defined. This study looks at the influence of the three regions on the validation results and suggests how the Feature Selective Validation (FSV) method can be applied in transient studies.Peer ReviewedPostprint (published version

EMI Risk Estimation for System-Level Functions Using Probabilistic Graphical Models

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.In general, the functions provided by complex systems often involve multiple sub-systems and components that are functionally dependent on each other. The dependency could be to receive power, control signals, input data, memory storage, feedback etc. With the increasing use of electronic systems to perform critical functions, the potential for malfunctions due to electromagnetic interference need to be identified and mitigated. Hence, a risk analysis, estimating the likelihood and severity of electromagnetic interference effects, is desirable from the very early stages of system development. In this paper, the use of probabilistic graphical models for estimating the likelihood of electromagnetic disturbances causing system malfunctions with various degrees of severity is demonstrated using a very simple case study. Statistical data are synthesised to illustrate the construction of conditional probability distribution tables for a Bayesian Network system model. Factorization and inference techniques are then applied to demonstrate the formulation and answer of queries that could be of value during system risk assessment

Electromagnetic Time Reversal to Locate Partial Discharges in Power Networks with Inhomogeneous cables using the Transmission Line Matrix Method

This work was supported by the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie Grant under Agreement 838681.This paper describes a method for the on-line location of partial discharges (PD) in power networks based on the electromagnetic time reversal (EMTR) theory. PDs are localized electrical discharges that partially bridge the insulation between conductors and that start in cable insulation defects. Since the insulation degradation is often caused by PD, PD is regarded as a symptom of insulation degradation and on-line PD location is considered the most suitable monitoring method of network integrity assessment to prevent faults and improve network resilience. The proposed method, reversing in time the measured PD signals, refocuses them to their source allowing the location of PD site. The method uses the Transmission Line Matrix modelling approach to solve the backward propagation equations. In this paper, the effectiveness of the EMTR-based method to locate PDs in inhomogeneous power lines, using only one measurement point at a line end, is investigated and proved in simulation

A new method to localize partial discharges on power cables using time reversal and TLM numerical method – A review

The file attached to this record is the author's final peer reviewed version.Insulation deterioration is often caused by partial discharge (PD) events. The adoption of on-line PD location methods is one of the most suitable methods to perform the power networks condition monitoring to improve their resilience and to guarantee electricity supply security. This paper reviews the results obtained in the design process of a new on-line PD location method based on the use of the electromagnetic time reversal (EMTR) theory and the Transmission Line Matrix (TLM) numerical method. Building on the work previously presented at the IWCS, where the method had been presented using two observation points, this paper shows further progress in this research and as a proof of its effectiveness, shows its ability in locating PDs using only one observation point. The procedure of the method is briefly described and its performance that overcomes the shortcomings of the traditional PD location methods are summarized. Finally, future related activities are described

Time Reversal for Partial Discharge Localization on Power Lines with Different Termination Impedances

This paper describes a new method for the on-line location of partial discharges (PDs) in power transmission and distribution networks based on Electromagnetic Time Reversal (EMTR) theory and on the Transmission Line Matrix (TLM) method in order to describe the time reversed propagation. In particular, the paper shows the effectiveness of the method in localizing the PD source when the impedances at the terminations of the line are unknown and describes the procedure to be followed in this case. The analysis is performed in simulation, and a model of the PD signal propagation that is able to reproduce the distortion phenomenon that affect the PD signal propagation on power lines and thus the accuracy of the on-line PD location methods is also described

Application to Real Power Networks of a Method to Locate Partial Discharges Based on Electromagnetic Time Reversal

This work was supported by the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie Grant under Agreement 838681.The paper presents an experimental validation of a method to locate partial discharges (PDs) on power distribution and transmission networks. The method is based on electromagnetic time reversal (EMTR) theory, and it uses a Transmission Line Matrix (TLM) model to describe the propagation of the PD signals in the reversed time. Since PDs are regarded as a symptom of insulation degradation, on-line PD location is considered an important approach to monitoring the integrity of a power distribution network, with the aim of detecting and preventing faults and improving network reliability. In this paper, the EMTR-based method is described and its effectiveness in PD localization using only one measurement point is demonstrated in three real 33 kV power lines. Its effectiveness is proved with and without an on-line electromagnetically noisy environment, and its accuracy is evaluated with respect to different signal-to-noise ratio (SNR) levels of the networks. The validation shows that the method is able to locate PDs with an error of 0.14% with respect to the total length of the line in the absence of noise, and with an error that is always lower than 0.5% for an SNR down to -7 dB