Other resources

Connecting Micro-Generators in Parallel to the Low Voltage Distribution Network Utilising Standard EN50438 in the Republic of Ireland

Liam Murphy — Fri, 05 Apr 2013 02:15:19 PDT

The green agenda has been much to the fore internationally and has particularly had an influence in Republic of Ireland (ROI) where there are ‘green’ ministers in Government. Mr. Eamon Ryan who is the Minister for Communications, Energy and Natural Resources has particularly championed the idea of self generation. The author’s interest in the subject matter is to investigate the up-take of micro-generation and determine the likely short term future along with the grid tie standard i.e. EN50438.

Issues surrounding micro-generation are considered from the international and national perspective and from a customer and generation utility point of view. The market for micro-generation in the ROI is examined and particularly the tariffs offered for export.

Two case studies are investigated; a micro-Combined Heat and Power (CHP) unit operational since early 2008 and a micro-wind unit which has become operational since February 2010. Type certification issues with Chinese manufactured wind turbines are discussed backed up with case studies from Northern Ireland (NI).

The principal methods of investigation were by researching, particularly by discussion (qualitative means) with key stakeholders in the ROI and United Kingdom (UK) and by research of the relevant literature. In addition, an analysis of the performance of a photovoltaic (PV) inverter located at DIT was carried out (quantitative analysis).

Micro-generation has important role to play from a national and international perspective in reducing dependence on central generation and in Green House Gases (GHG) reduction strategies. EN50438 has a role in ensuring the safe connection of grid tied micro-generation and has been adopted by Electricity Supply Board Networks (ESBN).

The Effects of Harmonics on Power Quality and Energy Efficiency

Alan Harrison — Wed, 21 Mar 2012 10:55:43 PDT

By making our electricity supply more secure, reliable and versatile will mean that we reduce our reliance upon oil, gas and solid fuels, which mostly exist outside of Ireland and the European community. The majority of our fuel is imported and this makes our economy dependent on outside interests and out of our control. Even more importantly as the world’s fossil fuel reserves are running out and electricity demand is ever increasing.

If we make our electricity networks secure and designed to the highest standards we can import and export electrical energy more easily as our demands change, for example by exporting to other European countries any surplus energy from wind farms or wave energy. This is achieved by paralleling all our power stations and micro generating plants, which consist of combined heat and power plants, wind turbines, hydro power, wave power and photovoltaic installations. These plants that are connected to the distribution system must be reliable and produce power of premium quality. Also the load itself must minimise its effect it has on power quality and the distribution system.

This dissertation will examine measure and quantify the effects that electrical harmonics have on our power quality and on our distribution system. Typical loads are examined, compact fluorescent lamps, switch mode power supplies, lamp dimming control and true and average RMS measurement of alternating currents.

Electromagnetic Scattering Solutions for Digital Signal Processing

Jonathan Blackledge (Thesis) — Thu, 26 May 2011 09:12:03 PDT

Electromagnetic scattering theory is fundamental to understanding the interaction between electromagnetic waves and inhomogeneous dielectric materials. The theory unpins the engineering of electromagnetic imaging systems over a broad range of frequencies, from optics to radio and microwave imaging, for example. Developing accurate scattering models is particularly important in the field of image understanding and the interpretation of electromagnetic signals generated by scattering events. To this end there are a number of approaches that can be taken. For relatively simple geometric configurations, approximation methods are used to develop a transformation from the object plane (where scattering events take place) to the image plane (where a record of some measure of the scattered field is taken). The most common approximation is the weak scattering approximation which ignores the effect of multiple scattering interactions and the first part of this thesis investigates the use of this approximation for electromagnetic imaging systems modeling. When scattering interactions become progressively more complex (e.g. multiple scattering from random media), the applications of deterministic scattering theory becomes difficult to use in practice. Consequently the inverse scattering problem can become ill-posed. For this reason, a number of other approaches are considered which include developing statistical models for the scattered field itself rather than the scatterer. In this thesis, we investigate the use of diffusion based models for solving the inverse scattering problem when strong scattering processes occur. We then extend this approach and consider the intermediate case by modelling the scattering processes using a fractional diffusion equation. Finally, a low frequency scattering theory is presented which leads to the proposition that light and other high frequency electromagnetic wavefields can be weakly diffracted by a low frequency scattered field. This leads to a new interpretation of gravity gravitational lensing which is investigated through the question as to why Einstein rings, observed in the visible spectrum, are blue?

The Fractal Market Hypothesis: Applications to Financial Forecasting

Jonathan M. Blackledge — Tue, 25 Jan 2011 10:24:13 PST

Most financial modelling systems rely on an underlying hypothesis known as the Efficient Market Hypothesis (EMH) including the famous Black-Scholes formula for placing an option. However, the EMH has a fundamental flaw: it is based on the assumption that economic processes are normally distributed and it has long been known that this is not the case. This fundamental assumption leads to a number of shortcomings associated with using the EMH to analyse financial data which includes failure to predict the future volatility of a market share value. This book introduces a new financial risk assessment model based on Levy statistics and considers a financial forecasting system that uses a solution to a non-stationary fractional diffusion equation characterized by the Levy index. Variations in the Levy index are considered in order to assess the future volatility of financial data together with the likelihood of the markets becoming bear or bull dominant, thereby providing a solution to securing an investment portfolio. The key hypothesis associated with this approach is that a change in the Levy index precedes a change in the financial signal from which the index is computed and can therefore be used as a risk management index. It is shown that there is a quantitative relationship between Levy's characteristic function and a random scaling fractal signal obtained through a Green's function solution to the fractional diffusion equation. In this sense, the model considered is based on the Fractal Market Hypothesis and two case studies are considered in this respect: (i) application of the hypothesis by predicting the volatility associated with foreign exchange markets; (ii) application to the ABX index.