This thesis describes the design of multivariable excitation controllers for synchronous generators, and their practical implementation on a laboratory machine system. The main objectives of the investigation were aimed at extending the steady-state stability limit of the generator and improving its general controllability. The present work is principally concerned with the implementation and test of the designs. Instrumentation has been developed to measure and combine feedback signals; this instrumentation and the laboratory generator system are described in detail. The performances of the controllers are predicted by computer simulation and evaluated by practical testing; attention is focussed on comparison of predicted and experimental performances. The theoretical basis of the design strategy is described, in which an optimal control algorithm applies the system states as feedback signals to the open-loop system, thereby shifting certain of the system eigenvalues to more desirable, predetermined locations. The state variables are selected as physically measurable quantities which obviates the need for implementing state estimation techniques.

The dairy farming sector of European Agriculture is currently under considerable economic pressure so the aim of each farmer should be to produce saleable milk, at the lowest cost. One important area of concern is the expenditure on hot water for hygiene, as to be acceptable to the buyer the milk must have a low level of contaminants. Clean milk is produced from clean, healthy udders by means of equipment which is adequately and appropriately cleaned. To facilitate this hygienic milk production most dairies are eguipped with heaters to provide water at 40°C (for cleaning udders) and 80- 100°C (for plant cleaning). The practice of udder washing is a subjective process as it depends on the operator's judgement of a 'clean' udder and his view of necessity. In England and Wales there are two only accepted methods of plant cleaning, circulation cleaning and Acidified Boiling Water (A. B. W.). Prior to the. audit described it was expected that water and electricity consumption for plant cleaning would be predictable. To date there has been little information on the volume and temperature of water used on commercial dairy farms and the electricty consumed to produce this hot water. It is therefore difficult for farmers to make informed judgement on methods of reducing their electricity costs. Thirteen farms in South Devon have been monitored, to establish current practice: farmers were questioned about their water use; electricity and water consumption were metered for two years; and cleaning practices were observed. This survey has revealed that many non-standard cleaning methods are used on dairy farms, making the prediction of water and electricity consumption difficult. The management of equipment has been revealed as the most important aspect in determining the energy used. A computer model has been produced to simulate water heating in the farm dairy, which can be used to advise farmers as to the energy cost of their cleaning practices. This model has .been successfully used on several of the farms surveyed, on one farm its use resulted in energy savings in excess of 400 kWh per month.

The need to make more efficient use of energy resources by improved methods of control, the deferment of expensive pipework reinforcement or replacement and the requirement to accommodate different loading patterns on sections of the gas network have made the requirement for effective feedback control essential. Gas distribution systems are large and complex and a major problem in applying conventional feedback techniques is the cost and reliability of transmitting the data necessary for automatic control. In order to overcome these difficulties, state estimation techniques have been investigated as a means of providing information about a distribution system from a minimum number of measurement points. The theoretical background to the study is reviewed including the modelling technique and the results of experimental work which has been performed on a distribution network in order to verify the techniques developed are presented. The results show that state estimation techniques have considerable potential for this type of application.

The work described in this thesis develops a strategy for planning domestic energy supply systems for small, rural communities. Two methods, for system optimisation are proposed: economic optimisation and thermodynamic optimisation. Both methods are applied to the small Scottish island of Eigg, as an example of a small community. It is shown that, for the range of energy equipment studied, the two methods are generally complementary. Economic theory and choice of parameters are discussed, as is the theoretical background to thermodynamic modelling. The net present value method is used to determine unit energy costs, which are used in the economic model as the parameter by which different energy sources are chosen. For thermodynamic assessment three parameters are used: exergy, second law efficiency and energy quality. Energy quality against quantity diagrams (on which areas represent exergy) are shown to be a useful way of visualising thermodynamic system performance. This work also develops methods which can be used to determine model inputs. These include: an energy census of the island of Eigg to determine the current energy system, development of a hydrological prediction model for determining hydro power potential, use of computer models to determine house space heating demands, and development of methods for predicting meteorological parameters from long term data. The application of the economic planning model to Eigg allows a much improved energy supply system for the island to be proposed. This makes energy more available, improves comfort (with regard to energy usage), and gives 30% higher energy usage for a lower unit cost than the islanders currently pay. The thermodynamic optimisation process improves the thermodynamic efficiency of the energy system on Eigg by more than 100% and shows which areas of energy technology should be investigated to harmonise economic and thermodynamic optimisation.

No description available.

No description available.

Energy conservation, the improvement of energy efficiency, is recognised as an important part of energy policy. This thesis examines the potential for conservation investment and possible energy savings, in part of the UK industrial sector. Assessments of the extent and type of energy conservation activity to date, both investments and energy management, within the brewing, malting, distilling and dairy sectors are made. Achievements to date affect future potentials. In the light of a model of technical change related to energy conservation several potentials are defined. The inter-related problems of estimating or measuring these and measuring performance in energy management are discussed. Some estimates of potentials, with explicit assumptions, are made for the four sectors studied. As any definition or measurement of potential is arbitrary, processes of change are also examined. A soft systems model of necessary activities in energy management is advanced and used to explore managerial barriers to profitable conservation investments in companies studied. Managerial factors for promoting successful energy management are discussed. Economic barriers to change are explored by profitability modelling for several energy conservation techniques used within the four sectors, including heat pumps and combined heat and power. The approach used throughout has been systematic and on several levels.

No description available.

No description available.

Στην παρούσα εργασία διερευνάται η βιοκλιματική δόμηση και αναλύονται θέματα άμεσα συνυφασμένα με αυτή. Ο βιοκλιματικός σχεδιασμός, στοχεύει στην εκμετάλλευση των θετικών περιβαλλοντικών παραμέτρων ώστε να μειωθούν οι ενεργειακές ανάγκες του κτιρίου καθ' όλη τη διάρκεια του έτους και να εξοικονομήσει τη συμβατική ενέργεια. Η εφαρμογή της βιοκλιματικής αρχιτεκτονικής μπορεί να οδηγήσει σε ενεργειακή ανεξαρτησία των μη Ανανεώσιμων Πηγών Ενέργειας έως 60%. Παράλληλα συμβάλλει στην αυξανόμενη μείωση των εκπομπών CO2. Η βιοκλιματική αρχιτεκτονική, στοχεύει στην κατασκευή βιώσιμων κατοικιών και πόλεων, έτσι είναι εξέχουσας σημασίας η χρησιμοποίηση ανανεώσιμων πηγών ενέργειας για την ορθή λειτουργία της κατοικίας. Στόχος είναι η κατασκευή κατοικιών που δεν ρυπαίνουν το περιβάλλον και καλύπτουν τις ανάγκες των ενοίκων με φυσικούς τρόπους χωρίς να τους επιβαρύνουν οικονομικά ούτε να προκαλούν προβλήματα στην υγεία τους και ρύπανση στο περιβάλλον. Στόχος της βιοκλιματικής αρχιτεκτονικής είναι επίσης η εξασφάλιση θερμικής, οπτικής και ακουστικής άνεσης, οι οποίες δημιουργούν ευχάριστα αισθήματα στους ενοίκους κατά τη διαμονή τους στην κατοικία και επιτυγχάνεται με την ορθή χρήση των παθητικών και των ενεργητικών συστημάτων, εφόσον υπάρχουν, σύμφωνα με τις προσωπικές ανάγκες των ενοίκων. Μέσα από αυτή την εργασία θα παρουσιάσω όλους εκείνους τους τρόπους-συστήματα (παραδοσιακά και σύγχρονα) που θα εντάξουν ένα κτίριο στην βιοκλιματική δόμηση. Όλα αυτά τα συστήματα είτε πρόκειται για ενεργητικά είτε για παθητικά έχουν ένα στόχο την εξοικονόμηση ενέργειας και την επίτευξη άνεσης με ότι αύτη περιλαμβάνει. / In this diploma thesis the bioclimatic building and many issues about this is, investigated and analyzed. The bioclimatic design, aims to exploit the positive environmental aspects to reduce the energy consumption of the building throughout the year and save non-renewable sources of energy. The application of bioclimatic architecture can lead to a 60% independence of non-renewable sources of energy. It can also contributes to a further reduction of carbon dioxide emissions. Bioclimatic architecture, aims to build sustainable homes and cities, so it is of utmost importance to use renewable sources of energy for the proper function of the residence. The aim is to build homes that do not pollute the environment and meet the needs of residents in natural ways without being a financial burden and cause health problems. The aim of bioclimatic architecture is also to ensure thermal, visual and acoustic comfort, which creates a pleasant feeling to the guests during their stay in the house. This can be reached with the proper use of passive and active systems, according to personal needs of occupants. Through this work I will present all those way-systems (traditional and modern) that will incorporate a building in bioclimatic construction. All these systems whether passive or active has a goal of saving energy and achieving comfort.