Uncertainty in wind energy forecasting

Wind energy is the energy source that contributes most to the renewable energy mix of European countries. While there are good wind resources throughout Europe, the intermittency of the wind represents a major problem for the deployment of wind energy into the electricity networks. To ensure grid security a Transmission System Operator needs today for each kilowatt of wind energy either an equal amount of spinning reserve or a forecasting system that can predict the amount of energy that will be produced from wind over a period of 1 to 48 hours. In the range from 5m/s to 15m/s a wind turbine’s production increases with a power of three. For this reason, a Transmission System Operator requires an accuracy for wind speed forecasts of 1m/s in this wind speed range. Forecasting wind energy with a numerical weather prediction model in this context builds the background of this work. The author’s goal was to present a pragmatic solution to this specific problem in the ”real world”. This work therefore has to be seen in a technical context and hence does not provide nor intends to provide a general overview of the benefits and drawbacks of wind energy as a renewable energy source. In the first part of this work the accuracy requirements of the energy sector for wind speed predictions from numerical weather prediction models are described and analysed. A unique set of numerical experiments has been carried out in collaboration with the Danish Meteorological Institute to investigate the forecast quality of an operational numerical weather prediction model for this purpose. The results of this investigation revealed that the accuracy requirements for wind speed and wind power forecasts from today’s numerical weather prediction models can only be met at certain times. This means that the uncertainty of the forecast quality becomes a parameter that is as important as the wind speed and wind power itself. To quantify the uncertainty of a forecast valid for tomorrow requires an ensemble of forecasts. In the second part of this work such an ensemble of forecasts was designed and verified for its ability to quantify the forecast error. This was accomplished by correlating the measured error and the forecasted uncertainty on area integrated wind speed and wind power in Denmark and Ireland. A correlation of 93% was achieved in these areas. This method cannot solve the accuracy requirements of the energy sector. By knowing the uncertainty of the forecasts, the focus can however be put on the accuracy requirements at times when it is possible to accurately predict the weather. Thus, this result presents a major step forward in making wind energy a compatible energy source in the future.

Current methods and advances in forecasting of wind power generation

Wind power generation differs from conventional thermal generation due to the stochastic nature of wind. Thus wind power forecasting plays a key role in dealing with the challenges of balancing supply and demand in any electricity system, given the uncertainty associated with the wind farm power output. Accurate wind power forecasting reduces the need for additional balancing energy and reserve power to integrate wind power. Wind power forecasting tools enable better dispatch, scheduling and unit commitment of thermal generators, hydro plant and energy storage plant and more competitive market trading as wind power ramps up and down on the grid. This paper presents an in-depth review of the current methods and advances in wind power forecasting and prediction. Firstly, numerical wind prediction methods from global to local scales, ensemble forecasting, upscaling and downscaling processes are discussed. Next the statistical and machine learning approach methods are detailed. Then the techniques used for benchmarking and uncertainty analysis of forecasts are overviewed, and the performance of various approaches over different forecast time horizons is examined. Finally, current research activities, challenges and potential future developments are appraised.

Power system parameters forecasting using Hilbert-Huang transform and machine learning

A novel hybrid data-driven approach is developed for forecasting power system parameters with the goal of increasing the efficiency of short-term forecasting studies for non-stationary time-series. The proposed approach is based on mode decomposition and a feature analysis of initial retrospective data using the Hilbert-Huang transform and machine learning algorithms. The random forests and gradient boosting trees learning techniques were examined. The decision tree techniques were used to rank the importance of variables employed in the forecasting models. The Mean Decrease Gini index is employed as an impurity function. The resulting hybrid forecasting models employ the radial basis function neural network and support vector regression. A part from introduction and references the paper is organized as follows. The second section presents the background and the review of several approaches for short-term forecasting of power system parameters. In the third section a hybrid machine learningbased algorithm using Hilbert-Huang transform is developed for short-term forecasting of power system parameters. Fourth section describes the decision tree learning algorithms used for the issue of variables importance. Finally in section six the experimental results in the following electric power problems are presented: active power flow forecasting, electricity price forecasting and for the wind speed and direction forecasting.

Reading Lydgate's Troy Book: patronage, politics, and history in Lancastrian England

This thesis, Reading Lydgate's Troy Book: Patronage, Politics and History in Lancastrian England, discusses the relationship between John Lydgate as a court poet to his patron Henry V. I contend that the Troy Book is explored as a vehicle to propagate the idea that the House of Lancaster is the legitimate successor to King Richard II in order to smooth over the usurpation of 1399. Paul Strohm's England's Empty Throne was a key influence to the approach of this thesis' topic. I examine that although Chaucer had a definitive impact on Lydgate's writing, Lydgate is able to manipulate this influence for his own ambitions. In order to enhance his own fame, Lydgate works to promote Chaucer's canon so that as Chaucer's successor, he will inherit more prestige. The Trojan war is seen in context with the Hundred Years War, and can be applied contextually to political events. Lydgate presents characters that are vulnerable to human failings, and their assorted, complicated relationships. Lydgate modernises the Troy Book to reflect and enhance his Lancastrian society, and the thesis gives a contextual view of Lydgate's writing of the Troy Book. Lydgate writes for a more varied target audience than his thirteenth-century source, Guido delle Colonne, and there is a deliberation on the female characters of the Troy Book which promulgates the theory that Lydgate takes a proactive and empathetic interest in women's roles in society. Furthermore Lydgate has never really been accepted as a humanist, and I look at Lydgate's work from a different angle; he is a self-germinating humanist. Lydgate revives antiquity to educate his fifteenth-century audience, and his ambition is to create a memorial for his patron in the vernacular, and enhance his own fame as a poet separate from Chaucer's shadow.

Dr. Richard Caulfield: antiquarian, scholar and academic librarian

The history of higher learning in Cork can be traced from its late eighteenth-century origins to its present standing within the extended confines of the Neo-Gothic architecture of University College, Cork. This institution, founded in 1845 was the successor and ultimate achievement of its forerunner, the Royal Cork Institution. The opening in 1849 of the college, then known as Queen's College, Cork, brought about a change in the role of the Royal Cork Institution as a centre of education. Its ambition of being the 'Munster College' was subsumed by the Queen's College even though it continued to function as a centre of learning up to the 1805. At this time its co-habitant, the School of Design, received a new wing under the benevolent patronage of William Crawford, and the Royal Cork Institution ceased to exist as the centre for cultural, technical and scientific learning it had set out to be. The building it occupied is today known as the Crawford Municipal Art Gallery.

The Irish House of Lords, 1780-1800: politics and ideology

This thesis covers the Irish House of Lords in the last two decades of its life. A number of important themes run through the work - the regency crisis, patronage, the management of the Lords, the relationship between the Lords and Commons. These themes, explored from different angles, are vital to an understanding of the political role of the upper house in the 1780s and 1790s. This study is confined to the Lords as a political institution and thus its judicial role as final court of appeal, which was restored to it in 1782, will not be explored here. The thesis consists of two parts. Part one examines the structure and powers of the House of Lords while part two looks at the parties and policies of the house. Chapter one discusses the British constitution as imposed upon Ireland. Chapter two suggests the reasons why constitutional changes were introduced in 1782, and looks at the contribution made by the Irish House of Lords in securing these changes. Chapter three explores the various channels of influence which the peers enjoyed. Chapter four explores the sometimes tense relationship between Lords and Commons. Chapter five examines management of the House of Lords by Dublin Castle. Part two, begins at chapter six. This chapter explores the leadership of both parties within the Lords. Chapter seven looks at how patronage was used to reward those who were loyal to the government. Chapter eight explores the influence of the Whig opposition. Chapter nine looks at the controversial attempts made by Pitt and his ministry during the 1790s to win the support of catholics and turn them from the lure of French ideas, and of the response of the peers to these attempts. Chapter ten is concerned with the relationship between the peers of the House of Lords and the lords lieutenant during the 1790s. Chapter eleven looks at the Union and the House of Lords and attempts to answer the question historians have long asked: why did the Irish parliament and the House of Lords in particular, look favourably on the proposed union of the two kingdoms and the end of their own institution? The House of Lords in the closing decades of the eighteenth century was an institution within which the wealth and power of the kingdom could be found. Its members were politically active, both inside and outside the house. It contained a majority who saw the Crown as the source of stability, but it was a living and evolving political organism and therefore it contained men who believed that the Crown should have its influence limited. This evolution is also demonstrated in its desire for political change in 1782 and 1788. Its last, and perhaps most radical decision, was to vote for its own demise in 1900.