Padej Pao-La-Or

Optimal overcurrent relay coordination using artificial bees colony algorithm

This paper presents optimal coordination of overcurrent relays by using artificial bees colony algorithm. The objective function of the relay coordination problem is to minimize the operation time of associated relays in the systems. The control variables used in this paper are the pickup current and time dial setting of relays. Quasi-Newton (BFGS), particle swarm optimization (PSO) and artificial bees colony (ABC) are employed to evaluate the search performance. For test, a 9-bus test power system was used. The simulation results showed that the artificial bees colony algorithm is capable to minimize the operation time of relays in the entire system. As a result, all search algorithms can solve optimal coordination relay which the artificial bees colony (ABC) gives the best solutions for coordination relay setting.

Analysis of temperature in solar thermal by 3-D finite element method

This paper presents a mathematical model of temperature in solar thermal which are evinced in the second-order partial differential equation. The solar thermal analysis uses copper pipe, aluminium pipe, and anodized aluminium pipe to compare temperature distribution of water from three types of pipe. In a computer simulation, 3-D finite element method established in MATLAB program were applied for temperature investigation. The result was shown the graphical performance of the water temperature in various type of pipe.

Study of Natural Frequencies and Characteristics of Piezoelectric Transformers by Using 3-D Finite Element Method

Piezoelectric transformers are electronic devices made from piezoelectric materials. The piezoelectric transformers as the name implied are used for changing voltage signals from one level to another. Electrical energy carried with signals is transferred by means of mechanical vibration. Characterizing in both electrical and mechanical properties leads to extensively use and efficiency enhancement of piezoelectric transformers in various applications. In this paper, study and analysis of electrical and mechanical properties in forms of potential and displacement distribution throughout the volume, respectively, are discussed and especially focused on around its natural frequency. This paper proposes a set of quasi-static mathematical model of electro-mechanical coupling for piezoelectric transformer by using a set of partial differential equations. Computer-based simulation utilizing the three-dimensional finite element method (3-D FEM) is exploited as a tool for calculation in two purposes. The first use is developed the 3-D FEM for identifying its natural frequencies while the second use is for visualizing potentials and displacements distribution within the piezoelectric transformer. The computer simulation based on the use of the FEM has been developed in MATLAB programming environment. In addition, which satisfactory results of natural frequencies are compared with those obtained from the experiment and the accuracy of 3-D FEM model is confirmed.