Lecturer, University of Benin
The Stirling engine technology lost its place in the market more than 100 years ago due to the more compact invention of the Otto and Diesel engines. Although, the Otto and Diesel engines are non-flexible fuel engines, their reduced weight to power ratio gave them an edge in countless industrial applications. However, due to the recent global warming, environmental pollution and energy crises coupled with the instability of oil prices, interest in Stirling engine technology for mitigating these issues is growing once again. This study is aimed at developing a simple numerical model for evaluating and predicting the performance of a gamma-type Stirling engine and to validate the model against current knowledge in the field.
Abstract: Nowadays, renewable energy systems have come up with more potential in power generation so as to meet the power demand. Among all the renewable systems, the wind energy generating system is believed to be at the peak. However, the wind energy‐based microgrid system is associated with many problems such as fluctuations in output voltage due to the fluctuated wind speeds and harmonics generations in the system. To address these issues, this article proposes a new method in order to achieve harmonic mitigation across its output by maintaining constant voltage. Nevertheless, particular attention has been given to the form and function of modular multilevel converter with multi‐winding transformer connected to the grid. Modular multilevel converter has been implemented with an advanced voltage controller tuned to control the voltage at its output. Also, a new system topology has been introduced with two wind turbines that are interconnected to multi‐winding transformer through asynchronous generators. The proposed system has been implemented with constant and variable wind speeds, and their respective results have also been analysed. The proposed scheme shows its effectiveness by theoretical calculations, verified by simulation and experimental results. Copyright © 2016 John Wiley & Sons, Ltd.
Pub.: 21 Jan '16, Pinned: 25 Sep '17
Abstract: The paper addresses the problem of controlling a solar thermal storage system with the purpose of achieving a desired thermal comfort level and energy savings. A solar thermal power plant is used for heating district houses with borehole seasonal energy storage. As the energy output from the solar thermal plant with borehole seasonal storage varies, the control system maintains the thermal comfort by using a servo controller. In this work, the modelling of the solar thermal system with borehole seasonal storage is inspired by the Drake Landing Solar Community in Okotoks, Alberta, Canada . The discrete model of the integrated energy system is obtained by using energy preserving Cayley-Tustin discretization. A simple and easily realizable servo control algorithm is designed to regulate the system operating at desired thermal comfort level despite disturbances from the solar thermal plant system, the borehole geo-thermal energy storage system and/or the district heating loop system. Finally, the performance of the servo controller and frequency analysis of the plant is given in simulation results section.
Pub.: 08 Jun '16, Pinned: 25 Sep '17