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Μόνιμο URI για αυτήν τη συλλογήhttps://dspace.library.tuc.gr/handle/123456789/115

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Advanced fuzzy logic controllers design and evaluation for buildings’ occupants thermal–visual comfort and indoor air quality satisfaction
(Elsevier, 2001) Kolokotsa Dionysia; Κολοκοτσα Διονυσια; Tsiavos D.; Stavrakakis Georgios; Σταυρακακης Γεωργιος; Kalaitzakis Kostas; Καλαϊτζακης Κωστας; Antonidakis E.
The aim of this paper is to present and evaluate control strategies for adjustment and preservation of air quality, thermal and visual comfort for buildings’ occupants while, simultaneously, energy consumption reduction is achieved. Fuzzy PID, fuzzy PD and adaptive fuzzy PD control methods are applied. The inputs to any controller are: the PMV index affecting thermal comfort, the CO2 concentration affecting indoor air quality and the illuminance level affecting visual comfort. The adaptive fuzzy PD controller adapts the inputs and outputs scaling factors and is based on a second order reference model. More specifically, the scaling factors are modified according to a sigmoid type function, in such a way that the measured variable to be as closer as possible to the reference model. The adaptive fuzzy PD controller is compared to a non-adaptive fuzzy PD and to an ON–OFF one. The comparison criteria are the energy required and the controlled variables response. Both, energy consumption and variables responses are improved if the adaptive fuzzy PD type controller is used. The buildings’ response to the control signals has been simulated using MATLAB/SIMULINK.
Genetic algorithms optimized fuzzy controller for the indoor environmental management in buildings implemented using PLC and local operating networks.
(Elsevier, 2002) Kolokotsa Dionysia; Κολοκοτσα Διονυσια; Stavrakakis Georgios; Σταυρακακης Γεωργιος; Kalaitzakis Kostas; Καλαϊτζακης Κωστας; Agoris D.
In this paper, an optimized fuzzy controller is presented for the control of the environmental parameters at the building zone level. The occupants’ preferences are monitored via a smart card unit. Genetic algorithm optimization techniques are applied to shift properly the membership functions of the fuzzy controller in order to satisfy the occupants’ preferences while minimizing energy consumption. The implementation of the system integrates a smart card unit, sensors, actuators, interfaces, a programmable logic controller (PLC), local operating network (LON) modules and devices, and a central PC which monitors the performance of the system. The communication of the PLC with the smart card unit is performed using an RS 485 port, while the PLC-PC communication is performed via the LON network. The integrated system is installed and tested in the building of the Laboratory of Electronics of the Technical University of Crete.
Interconnecting smart card system with PLC controller in a local operating network to form a distributed energy management and control system for buildings
(Elsevier, 2002) Kolokotsa Dionysia; Κολοκοτσα Διονυσια; Kalaitzakis Kostas; Καλαϊτζακης Κωστας; Antonidakis E.; Stavrakakis Georgios; Σταυρακακης Γεωργιος
Distributed control and energy management for buildings is a viable solution, ensuring both indoor comfort for the occupants and reduction of energy consumption. The aim of this paper is to present the architecture of a distributed building energy management system that can be installed in new as well as in existing buildings, which are more energy inefficient. The system integrates a smart card unit, acting as a user machine interface, sensors, actuators, interfaces, a PLC controller that incorporates the fuzzy control algorithm, local operating network (LON) modules and devices and an optional PC which monitors the performance of the system. The distributed control architecture is based on the properties of the LON. The complete system is installed and tested in the Laboratory of Electronics of the Technical University of Crete.
Local operating networks technology aiming to improve building energy management system performance satisfying the users preferences
(Taylor & Francis, 2001) Kolokotsa Dionysia; Κολοκοτσα Διονυσια; Kalaitzakis Kostas; Καλαϊτζακης Κωστας; Stavrakakis Georgios; Σταυρακακης Γεωργιος; Sutherland George; Eftaxias George
The available Building Energy Management Systems (BEMS), although they contribute to a significant reduction of energy consumption and improvement of the indoor environment, they can only be implemented in new buildings. Their installation in existing buildings is far from being cost effective due to the incompatibility of communication protocols between BEMS designed by various manufacturers and unavoidable modifications for data transmission. On the other hand, current research for energy efficient buildings has proved that although the design and the facilities including BEMS aim to satisfy the thermal and visual comfort plus the air quality demands while minimising the energy needs, they often do not reach their goals due to users interference. Latest trends in designing Intelligent Building Energy Management Systems (IBEMS) offer a Man Machine Interface that could store the users preferences and adapt the control strategy accordingly. The objectives of the present paper are to present the advantages of the use of a man machine interface based on a smart card terminal together with fuzzy control techniques in satisfying the users preferences plus to underline the capabilities that the LON network offers to the design. A fuzzy PID controller is developed to reach the first of the above objectives. The monitoring of the energy consumption along with satisfying the users preferences is achieved by the use of a suitable cost function for the whole system. All the above parameters as well as the cost function are kept between acceptable limits. The overall control system including the cost function is modeled and tested using MATLAB/SIMULINK. The implementation of the control system in an existing building requires interconnection of sensors and actuators installed across the building, is well served by the LonWorks technology due to its high standards and flexibility features.
Short-term load forecasting based on artificial neural networks parallel implementation.
(Elsevier, 2002) Kalaitzakis Kostas; Καλαϊτζακης Κωστας; Stavrakakis Georgios; Σταυρακακης Γεωργιος; Anagnostakis E.
This paper presents the development and application of advanced neural networks to face successfully the problem of the short-term electric load forecasting. Several approaches including Gaussian encoding backpropagation (BP), window random activation, radial basis function networks, real-time recurrent neural networks and their innovative variations are proposed, compared and discussed in this paper. The performance of each presented structure is evaluated by means of an extensive simulation study, using actual hourly load data from the power system of the island of Crete, in Greece. The forecasting error statistical results, corresponding to the minimum and maximum load time-series, indicate that the load forecasting models proposed here provide significantly more accurate forecasts, compared to conventional autoregressive and BP forecasting models. Finally, a parallel processing approach for 24 h ahead forecasting is proposed and applied. According to this procedure, the requested load for each specific hour is forecasted, not only using the load time-series for this specific hour from the previous days, but also using the forecasted load data of the closer previous time steps for the same day. Thus, acceptable accuracy load predictions are obtained without the need of weather data that increase the system complexity, storage requirement and cost.
A Simulation Model for the Reliable Integration of a 4.5MW Wind Farm into the Power Grid of the Crete Island
(Taylor & Francis, 1990) Kalaitzakis Kostas; Καλαϊτζακης Κωστας; Stavrakakis Georgios; Σταυρακακης Γεωργιος
This paper describes a computer simulation model which has been developed to study the effects of integrating wind energy conversion systems (WECS) into autonomous power systems. The quality of the interconnected system performance is specified in terms of operational constraints. Load-flow and power-system-stability studies were preformed in order to evaluate the penetration impact of a 4·5 MW wind farm on the local grid fo Sitia-Crete. The results show that the above wind energy penetration level will not cause any problem to the existing electric power grid.
Size optimization of a PV system installed close to sun obstacles.
(Elsevier, 1996) Kalaitzakis Kostas; Καλαϊτζακης Κωστας; Stavrakakis Georgios; Σταυρακακης Γεωργιος
The assessment of the optimal size of a PV-array/battery-storage system, when the incident solar radiation is considerably obstructed, is presented in this article. An optimal dimensioning method is proposed based on a new procedure for the calculation of the actual solar radiation on the array surface, for installations located near obstacles. The optimum tilt of the PV array is also computed and the resulting optimal PV-array/battery-storage system is evaluated by an appropriate routine. The results of the application of the complete algorithm for a real case study inside a gorge are illustrated.

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