Multi-train modeling and simulation integrated with traction power supply solver using simplified Newton–Raphson method

Railway Engineering Science - Multi-train modeling and simulation plays a vital role in railway electrification during operation and planning phase. Study of peak power demand and energy consumed...     

The potential micro-hydropower projects in Nakhon Ratchasima province,Thailand

At present, fossil fuel energy is commonly used in developing countries, including Thailand. The tendency to use fossil fuel energy is continuously increasing, and the price of fossil fuels is rising. Thus, renewable energy is of interest. Hydropower is one of the oldest renewable energy forms known and one of the best solutions for providing electricity to rural communities. The present paper aims to determine the potential micro-hydropower sites that could provide more than 50 kW but not over 10 MW in Nakhon Ratchasima Province, Thailand. Both reservoir and run-of-the-river schemes are considered for the assessment of potential micro-hydropower sites. For the reservoir scheme, the discharge in the reservoir is employed for generating micro-hydropower electricity. This installation can be carried out without major modifications to the dam. The run-of-the-river scheme diverts water flow from the river mainstream to the intake via a pressure pipe or an open canal, which is then conveyed to the turbine via a penstock to generate electricity. The results showed that there are 6 suitable projects for the reservoir scheme and 11 suitable projects for the run-of-the-river. The maximum power load was 6000 kW and 320 kW for the reservoir and the run-of-the-river schemes, respectively. Hydropower from the run-of-the-river scheme is more suitable than hydropower from the reservoir scheme because of the many mountains in this province. The designed head for the run-of-the-river scheme is thus generally higher than that for the reservoir scheme. Because stream flow during the dry season is very low, electricity can only be produced in the wet season. This research is a pilot study to determine the potential sites of micro-hydropower projects.     

Control of paralleled single-phase motors for a crop chopping machine

This article proposes a fuzzy control system for driving multiple single-phase induction motors in parallel connection. The drive system employs only a single PWM inverter controlled by a self-organizing fuzzy controller. This drive and control system has been utilized in an invented crop chopping machine. The article presents the control system concept, modeling of multiple motors in parallel connection, controller design, simulation of the closed-loop system and practical results. The control system stability is also analyzed on the basis of passivity theorem.     

Optimal power flow solution using improved harmony search method

This paper describes the improved harmony search method (IHS) to solve optimal power flow (OPF) problems. The harmony search is one of meta-heuristic search methods inspired by the improvisation of musicians developed by Geem (2001) [23]. The proposed algorithm was tested with five standard IEEE test systems (6-bus, 14-bus, 30-bus, 57-bus and 118-bus test systems). The tests were divided into smooth and non-smooth fuel-cost cases. The comparisons among solutions obtained by sequential quadratic programming (SQP), genetic algorithms (GA) and IHS were conducted. As revealed from the simulated results, the effectiveness of the IHS for solving OPF problems was confirmed.