Engineering Commons^™

The Application Of Multi Frequency Resonant Controllers In In A Dfig To Improve Performance By Reducing Unwanted Power And Torque Pulsations And Reducing Current Harmonics., Joseph Kearney, Michael Conlon, Eugene Coyle

Conference papers

The paper describes a method to control the rotor-side and grid side converters in a DFIG when subjected to the effects of network voltage unbalance conditions. Multi Frequency Resonant Controllers are incorporated into the grid side and rotor side converters to assist in the control functions. The Resonant Controllers are tuned to twice the network frequency to assist in the control of power and torque pulsations and to three times the network frequency to assist in the control of the generated third harmonic currents. A DFIG model is implemented in Matlab/Simulink and simulations show the reduction in power and torque …

The Application Of Multi Frequency Resonant Controllers In In A Dfig To Improve Performance By Reducing Unwanted Power And Torque Pulsations And Reducing Current Harmonics., Joseph Kearney, Michael Conlon, Eugene Coyle

Conference papers

The paper describes a method to control the rotor-side and grid side converters in a DFIG when subjected to the effects of network voltage unbalance conditions. Multi Frequency Resonant Controllers are incorporated into the grid side and rotor side converters to assist in the control functions. The Resonant Controllers are tuned to twice the network frequency to assist in the control of power and torque pulsations and to three times the network frequency to assist in the control of the generated third harmonic currents. A DFIG model is implemented in Matlab/Simulink and simulations show the reduction in power and torque …

Evaluation Of A Part-Time Engineering Degree Programme That Aimed To Unify And Diversify, Kevin Kelly, Vincent Kenny

Conference papers

The School of Electrical Engineering within DIT attempted to address the challenge of increasing diversity in Engineering Education by developing a part-time Electrical Services Engineering degree programme that began as a certificate in 2001 and as a degree in 2003. This four year evening programme had a number of innovations: • Recognition of Prior Learning (RPL) • Application of a Student Centred paradigm • Innovative Curriculum Development using Constructivist principles and Project Based Learning (in part) This paper will be an evaluation of the four year part time degree programme. There are issues deserving investigation with regard to the programme. …

Wavelet Based Islanding Detection Of Dc-Ac Inverter Interfaced Dg Systems, Mohamed Moin Hanif, Malabika Basu, Kevin Gaughan

Conference papers

The increased penetration of distributed generation (DG) often connected to grid through dc-ac interface has made islanding detection an important and challenging issue to power engineers. Several methods based on passive and active detection scheme have been proposed in the literature. While passive schemes have a large non detection zone (NDZ), concern has been raised on active method due to its degrading power quality effect. This paper proposes a wavelet based passive islanding detection scheme with almost zero NDZ for dc-ac inverter interfaced grid connected DGs. The key idea is to utilize the spectral changes in the higher frequency components …

Analysis Of Engineering Students Learning Styles On Level 7, Level 8 And Level 9 Programmes, Aidan O'Dwyer

Conference papers

This contribution reports on research, carried out over three academic years, into the learning styles of engineering students, on a number of Level 7, Level 8 and Level 9 programmes at DIT, using the index of learning styles survey developed by Felder and Soloman (1991). The contribution explores the results obtained in detail, placing them particularly in the national context. The correlation between student performance and individual learning styles is examined. Knowledge of the strongly visual learning style of these cohorts of students may be used to improve the learning environment.

High Performance Modified Dsr Routing Protocol For Wlan Mesh Networks, Mustafa Ramadhan, Mark Davis

Conference papers

This work presents a cross-layer modification to the DSR protocol which discovers high throughput paths on multi-hop wireless mesh networks. The modified DSR incorporates a metric based upon the bandwidth availability at a node into the routing discovery mechanism. We introduce the Access Efficiency Factor (AEF) as an alternative metric to the hop-count for the routing selection mechanism. In this modification, the selected path is identified by finding a path with the highest minimum AEF value. The OPNET modeler has been employed to investigate the performance of the modified DSR protocol on randomly generated network opologies of different node densities. …

Information Hiding Using Stochastic Diffusion For The Covert Transmission Of Encrypted Images, Jonathan Blackledge

Conference papers

A principal weakness of all encryption systems is that the output data can be `seen' to be encrypted. In other words, encrypted data provides a 'flag' on the potential value of the information that has been encrypted. In this paper, we provide a novel approach to `hiding' encrypted data in a digital image. We consider an approach in which a plaintext image is encrypted with a cipher using the processes of `stochastic diffusion' and the output quantized into a 1-bit array generating a binary image cipher-text. This output is then `embedded' in a host image which is undertaken either in …

Power Quality In Grid Connected Renewable Energy Systems: Role Of Custom Power Devices, Shafiuzzaman Khan Khadem, Malabika Basu, Michael Conlon

Conference papers

This paper deals with the technical review of power quality problems associated with the renewable based distributed generation systems and how the custom power devices like STATCOM, DVR and UPQC play important role in power quality improvement. IEEE and IEC standard for the grid connected renewable energy systems are one of the critical point of interest for the selection of custom power devices. Special attention has been given on the compensation of reactive power, harmonic current and voltage fluctuation during the interconnected as well as islanding mode of operation. As the solar and wind are the most abundant resources therefore …

The Control Of Rotor Side And Grid Side Converters In A Dfig During Network Voltage Unbalance Conditions Using Resonant Current Controllers., Joseph Kearney, Michael Conlon, Eugene Coyle

Conference papers

This paper implements control techniques to enable improved operation of DFIG’s when subjected to the effects of network voltage unbalance conditions. The control scheme involves the integration of a resonant regulator into the PI controllers of both the rotor side and grid side converters in a DFIG. The resonant controller is tuned to twice the network frequency (2ω_e) and designed to mitigate against the oscillations in a DFIG due to network voltage unbalance conditions. The grid side converter controller also incorporates a second resonant controller tuned to three times the grid frequency (3ω_e) to alleviate the …

Novel Ac Side P&O Maximum Power Transfer Control For Grid Connected Photovoltaic Systems, Mohamed Moin Hanif, Malabika Basu, Kevin Gaughan

Conference papers

Grid connected Photovoltaic inverters can convert PV energy into electricity with very high efficiencies. Power from the PV panels fluctuates depending on various weather conditions. PV inverters usually include a maximum power point tracker (MPPT) to track this varying power, in order to transfer all the available power to the grid efficiently. Control of power transferred to the grid along with the MPPT plays a crucial role in determining the efficiency of a PV system. This paper discusses about the basic power transfer theory between sources (PV and Grid) and focuses on the need of a DC-DC boost circuit, along …

Locating Tune Changes And Providing A Semantic Labelling Of Sets Of Irish Traditional Tunes, Cillian Kelly, Mikel Gainza, David Dorran, Eugene Coyle

Conference papers

An approach is presented which provides the tune change loactions within a set of Irish traditional turnes. Also provided are semantic labels for each part of each tune within the set. A set in Irish traditional music is a number of individual tunes played segue. Each of the tunes in the set are made up of structural segments called parts. Musical variation is a prominent characteristic of this genre. However, a certain set of notes known as "set accented tones" are considered impervious to musical variation. Chroma information is extracted at "set accented tone" locations within the music. The resulting …

Exploiting Glottal Formant Parameters For Glottal Inverse Filtering And Parameterization, Alan O'Cinneide, David Dorran, Mikel Gainza, Eugene Coyle

Conference papers

It is crucial for many methods of inverse filtering that the time domain information of the glottal source waveform is known, e.g. the location of the instant of glottal closure. It is often the case that this information is unknown and/or cannot be determined due to e.g. recording conditions which can corrupt the phase spectrum. In these scenarios, alternative strategies are required. This paper describes a method which, given the parameters of the glottal formant of the signal frame, can accurately parameterize the glottal shape source and vocal filter for a broad range of voice quality types and which is …

Harmonic/Percussive Separation Using Median Filtering, Derry Fitzgerald

Conference papers

In this paper, we present a fast, simple and effective method to separate the harmonic and percussive parts of a monaural audio signal.The technique involves the use of median filtering on a spectrogram of the audio signal, with median filtering performed across successive frames to suppress percussive events and enhance harmonic components, while median filtering is also performed across frequency bins to enhance percussive events and supress harmonic components. The two resulting median filtered spectrograms are then used to generate masks which are then applied to the original spectrogram to separate the harmonic and percussive parts of the signal. We …

Interactive Music Archive Access System, Martin Gallagher, Derry Fitzgerald, Dan Barry, Matt Cranitch, Eugene Coyle

Conference papers

The goal of the Interactive Music Archive Access System (IMAAS) project was to develop an interactive music archive access system which was capable of allowing an end-user to easily extract rhythmic, melodic and harmonic musical metadata descriptors from audio, and allow the user to interact with the archive contents in a manner not typically allowed in archive access systems. To this end, the IMAAS system incorporates a range of real-time interaction tools which allow the user to modify the retrieved audio in a number of ways including the ability to isolate individual instruments in stereo mixes, pitch and time-scale modification, …

Audio Thumbnail Generation Of Irish Traditional Music, Cillian Kelly, Mikel Gainza, David Dorran, Eugene Coyle

Conference papers

An approach is presented which generates an audio thumbnail of Irish traditional music. An audio thumbnail is consered to be the most representative segment of the music. For popular music, the chorus is considered to be an ideal audio thumbnail, however in Irish Traditional Music there is no chorus. An Irish Traditional tune consists of tow or mor short structural segments called parts. Parts are repeated to extend the tuen, and the tune itself is also repeated once or more in its entirety. To further extend a performance, tunes are concatenated to form a set of tuens. As a result, …

On The Use Of A Dynamic Hybrid Tempo Detection Model For Beat Tracking, Mikel Gainza

Conference papers

In this paper, an approach that estimates the times at which musical beats occur is presented. The system uses a hybrid multi-band decomposition in order to estimate the music tempo. Following this, beat events are tracked by using a dynamic programming approach, which is updated by using short time tempo estimates. The hybrid decomposition is used in order to calculate the tempo by using different onset detection functions in different frequency bands. In addition, a method that estimates which frequency bands provide reliable periodicities is also presented. The accuracy of the model is evaluated by comparing the presented system against …

E-Fraud Prevention Based On The Self-Authentication Of E-Documents, Jonathan Blackledge, Eugene Coyle

Conference papers

We consider a method for preventing e-Fraud in which a binary image is encrypted with a floating point cipher using a convolution operation and the output quantized into a 1-bit array generating a binary image ciphertext. The output is then ‘embedded’ in a host image to hide the encrypted information. Embedding is undertaken either in the lowest 1-bit layer or multiple 1-bit layers. Decryption is accomplished by: (i) extracting the binary image from the host image; (ii) correlating the result with the original cipher. In principle, any cipher generator can be used for this purpose and the method has been …

Experiences Of Assessment Using Multiple Choice Questions On Advanced Modules Taken By Level 8 And Level 9 Engineering Students, Aidan O'Dwyer

Conference papers

This contribution evaluates the use of multiple-choice questions, in both formative and summative assessment modes, on advanced modules taken by Level 8 and Level 9 engineering students, over the past two academic years. Assessment data, and student experiences with the assessment methods, are reported and analysed.

Estimating The Yield Of Micro Wind Turbines In An Urban Environment: A Methodology, Keith Sunderland, Michael Conlon

Conference papers

Micro wind turbines currently have the majority share of micro (electricity) generation installations in Ireland. These technologies are being installed predominantly in rural environments, and current applications to the Distribution Services Operator (DSO) for connection of all types of micro generator stand at less than 500. Poor market dissemination of information and research findings compounded with poor options for spill payment - as well as onerous planning restrictions do not –it appears - create a platform conducive to encouraging development in this market.

This paper outlines the complexities associated with evaluating the wind resource within an urban environment and investigates …

On The Appearance Of A Positive Real Pole In The Results Of Glottal Closed Phase Linear Prediction, Alan O'Cinneide, David Dorran, Mikel Gainza, Eugene Coyle

Conference papers

Often when performing glottal closed phase covariance linear prediction, a positive real pole can appear in the resulting filter transfer function. The commonly adopted approach is to discard this pole, as it does not fit with the usual model of the all-pole vocal tract filter. However, this real pole describes some aspect of the speech signal; this paper provides a novel perspective on its occurrence. This viewpoint has a useful implication to the speech community, especially from the perspective of fitting a glottal pulse to the inverse filtered signal, as the real pole describes the return phase of the glottal …

Towards A Method To Determine The Glottal Formant Parameters Of Voiced Speech Without Time-Domain Reference, Alan O'Cinneide, David Dorran, Mikel Gainza, Eugene Coyle

Conference papers

This paper presents an approach to estimate the glottal formant parameters of the voicing source in the frequency-domain. The method is based on a simplified pole-zero interpretion of the prevalent Liljencrants-Fant (LF) model of glottal flow, and gives approximations for a broad range of pulses shapes. An advantage of the method is that, unlike other methods, it does not rely on time-domain references.

Interactive Music Archive Access System, Martin Gallagher, Mikel Gainza, Derry Fitzgerald, Dan Barry, Matt Cranitch, Eugene Coyle

Conference papers

The goal of the Interactive Music Archive Access System (IMAAS) project was to develop an interactive music archive access system which was capable of allowing an end-user to easily extract rhythmic, melodic and harmonic musical metadata
descriptors from audio, and allow the user to interact with the archive contents in a manner not typically allowed in archive access systems. To this end, the IMAAS system incorporates a range of real-time interaction tools which allow the user to modify the retrieved audio in a number of ways including the ability to isolate individual instruments in stereo mixes, pitch and timescale modification, …