Sevki Demirbas

A novel web-based laboratory for DC motor experiments

This article introduces a novel web‐based DC motor laboratory, called NeTRe‐LAB, to support teaching electrical machines. The NeTRe‐LAB includes favorable animations to facilitate understanding characteristics of the DC motor, interactive DC motor models for instructive simulations, and web‐based experiments with online monitoring features. To illustrate the current operations, remote access to an experimental setup of a DC motor has been provided and the speed control of it has been realized over Internet. The evaluation results have shown that the NeTRe‐LAB presented in this study provides encouraging aspects, services, and support system for higher education.

A Novel Integrated Web Based Learning System for Electrical Machines Education

This study introduces a novel web based learning tool for electrical machines education. The tool developed consists of the real time experiments remotely accessible via internet in addition to thereotical presentations with animations and simulations on mathematical models of the electrical machines. The system is based on server/client architecture. All operation steps are executed by the server. So, clients do not need any additional software rather than internet connection and an internet browser. A DC motor course is given as an example to illustrate the novel tool developed. The remotely located users can learn the therotical information about the DC motor by means of using interactive web pages. All thereotical presentations supported with favorable animations to facilitate the understanding. Also, users can use the simulation models over the web to observe the motors dynamic behaviours under the different parameters. Moreover, they can remotely access a DC motor experimental set via internet to perform real time experiments such as speed control and generator operation of DC motor. During the conducting real time experiments over the web, the experimental set can be monitored with a webcam. Experimental results show that the integrated web based learning system developed is user-friendly and can be used for electrical machines education successfully.

Building of W&S energy system

This study introduces building and operation of a wind and a solar power sources as a clean energy park. This park includes efficient wind and solar power sources that are controlled by a PIC microcontroller to manage the energy storage in batteries and the parallel connection of the system with the grid. There are 14 solar panels producing 2.5 kW in total and a 2.5 kW wind turbine installed in the system. Alternating current energy obtained from wind turbine and direct current energy obtained from solar panels are collected on the direct current bar, where the level of the direct current voltage is kept constant. A hybrid system based on microcontroller has been applied in this study to control the power flow in all directions between the wind turbine, the solar panels, the batteries and the grid.

Effects of renewable energy sources on the power system

Recently, growing electrical energy market and increasing integration of renewable energy sources (RES) in power systems have lead to new challenges on network planning step and operation, thus it is required to investigate and analyze properly the impacts of integrated RES on the power system. In this paper, the electricity transmission network with wind farms (WF) is modeled. For the grid model, a part of Izmir region is chosen due to the amount of installed generation plants based RES especially wind energy in this region. The comparison between unexpected variations to voltage profile of the power system before and after RES integration to the power system is demonstrated. In the modeling of the electricity transmission network with RES, Digsilent/Power Factory is used as software. The different case studies in integration of different amounts of RES are implemented on the developed grid model. As a result of the conducted case studies, effects of RES on existing power system are evaluated and graphics obtained from the simulation are presented. Especially, the voltage profile of power system is examined.

Microgrid facility around Asia and far east

The surprising rates of electrification have experienced numerous populated counties in Asian region such as Bangladesh, Indian, China and Indonesia. To meet the increased demand for both power and grid services across the region will require innovation approach and the term discrete power system microgrid has introduced. As the reliability and quality of power demand have increased day by day, power industry faces many problems including rising cost of energy, power quality and stability, aging infrastructure, mass electrification, climate change and so on where people have focused on low voltage or medium voltage distribution generation. Microgrid has served several goals for the society in term of reliability, sustainability and economic power operation. Besides, feasibility of microgrid is wide spread such as various region of underdeveloped Asian subcontinent especially in remote village and Islands. This paper has a detail description of perspective and existing microgrid around this region and its future application. Moreover, the information of microgrid has tabulated here so that researcher and designer would get help from it along with they might know what have done so far in this field and what is going up. The market of microgrid has increased dramatically since last decade and government has focused on quality of community life by harvesting maximum renewable power.

Active and reactive power control of grid connected permanent magnet synchronous generator in wind power conversion system

With the advances of power electronic technologies and permanent magnet materials, there have been great interest to direct driven permanent magnet synchronous generators (PMSG) among wind turbine manufactures. Since PMSG directly connected to the wind turbine, controlling of the power electronic converters has vital role at gearless connection. This paper presents grid side converter (GSC) control algorithm for a grid connected PMSG used in wind power conversion system. In developed system operation of the GSC are controlled by using vector control algorithm and a PLL algorithm is employed for compensation of phase difference between grid and GSC voltage. Operation of the system has been verified through simulation.

Investigation of current harmonics using FEM on different rotor types of PMSMs

Current harmonics of the permanent magnet synchronous motors (PMSMs) varies with the shaft structures. These harmonics produce additional loses at both windings and the core of a PMSM and increase the temperature inside the machine. Such a temperature increase affects the machine parameters and the efficiency. Therefore, in order to obtain the optimum operating conditions of a PMSM, current harmonics should be analyzed. In the present study, two types of rotors for a PMSM have been simulated and evaluated with a current controlled voltage source inverter (VSI) by the help of a 3D finite element method. As a result of these simulations, motor current harmonics are examined by using the Hamming method at different modulation frequencies and the outputs of efficiencies, torques, powers and the induced voltages on windings are compared for these shaft structures. It has been proven that the current ripples and harmonics may be decreased to some extend by using a symmetrical structure among the proposed structures.

Stability analysis of an offshore wind farm connected to turkish electricity transmission system

Complexing power systems and increasing the amount of renewable energy sources (RES) in the power systems have caused new challenges such as stability, security problem, thus the analysis of stability in the power systems has become very crucial in order to maintain system equilibrium. In this paper, the electricity transmission network with an offshore wind farm (OWF) is modeled. For the grid model, a part of Turkish Electricity Transmission System, near to Gallipoli region, is chosen due to variation of generations and balance between load and generation in this region. In aspect of system stability, the voltage stability analyses with and without an OWF connected to Turkish Electricity Transmission System are demonstrated. Using active power-voltage (P-V) curve and reactive power-voltage (Q-V) curve, the voltage stability analyses has been carried out. In the modeling of the electricity transmission network with the OWF, Digsilent/Power Factory is used as software.

Design and application of a control system for DC motors over power line

Communicating high frequency control signals over a power lines is well known and getting popular day by day. This technique is known as power line communication (PLC) and mostly used to control the loads in short distance. In this study, authors present to control a DC motor over a power line. For this purpose, a transmitter and receiver have been used on the power line. High frequency control signals are sent by the transmitter and received by the receiver at other side of the line. In this way, DC motors is run and stop. This whole system is controlled by a microprocessor PIC16F877A at 33 kHz. Experimental results show that the proposed system is successful and can be applicable for controlling of other loads.

Design and implementation of DSP-based three-phase PFC

In this study, DSP based three phase PFC system for switching devices such as switching mode power supplies has been designed and implemented. The experimental set uses MATLAB/SIMULINK compatible eZdsp F2812 target equipped with a TI TMS320F2812 DSP. The DSP produces the driving signals by realizing control algorithm, current control and PWM modulation methods. MATLAB/SIMULINK software has been used to modeling of control algorithm, current control and PWM modulation techniques. Therefore more flexible control system has been carried out while reducing software writing time. Experimental results show that, input current of PFC system is in phase with utility voltage and its total harmonic distortion (THD) is in the range described at international standards.