Eftichios Koutroulis

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Maximum power point tracking (MPPT) is used in photovoltaic (PV) systems to maximize the photovoltaic array output power, irrespective of the temperature and irradiation conditions and of the load electrical characteristics. A new MPPT system has been developed, consisting of a Buck-type dc/dc converter, which is controlled by a microcontroller-based unit.(More)
A methodology for optimal sizing of stand-alone PV/WG systems is presented. The purpose of the proposed methodology is to suggest, among a list of commercially available system devices, the optimal number and type of units ensuring that the 20-year round total system cost is minimized subject to the constraint that the load energy requirements are(More)
A wind-generator (WG) maximum-power-pointtracking (MPPT) system is presented, consisting of a highefficiency buck-type dc/dc converter and a microcontroller-based control unit running the MPPT function. The advantages of the proposed MPPT method are that no knowledge of the WG optimal power characteristic or measurement of the wind speed is required and the(More)
Pulse width modulation (PWM) has been widely used in power converter control. Most high power level converters operate at switching frequencies up to 500 kHz, while operating frequencies in excess of 1 MHz at high power levels can be achieved using the planar transformer technology. The contribution of this paper is the development of a high-frequency PWM(More)
System latency (time delay) and its visible consequences are fundamental Virtual Environment (VE) deficiencies that can hamper user perception and performance. This paper presents an immersive simulation system which improves upon current latency measurement and minimization techniques. Hardware used for latency measurements and minimization is assembled(More)
This paper presents a new methodology for optimal design of transformerless photovoltaic (PV) inverters targeting a cost-effective deployment of grid-connected PV systems. The optimal switching frequency as well as the optimal values and types of the PV inverter components is calculated such that the PV inverter LCOE generated during the PV system lifetime(More)
In recent years, estimating the power output of inherently intermittent and potentially distributed renewable energy sources has become a major scientific and societal concern. In this paper, we provide an algorithmic framework, along with an interactive web-based tool, to enable short-to-middle term forecasts of photovoltaic (PV) systems and wind(More)
Data-acquisition systems are widely used in renewable energy source (RES) applications in order to collect data regarding the installed system performance, for evaluation purposes. In this paper, the development of a computer-based system for RES systems monitoring is described. The proposed system consists of a set of sensors for measuring both(More)
Environmental variables monitoring with wireless sensor networks (WSNs) is invaluable for precision agriculture applications. However, the effectiveness of existing low-power, conventional (e.g. ZigBee-type) radios in large-scale deployments is limited by power consumption, cost and complexity constraints, while the existing WSN solutions employing(More)