Turan Demirci

Reactive-Power Compensation of Coal Mining Excavators by Using a New-Generation STATCOM

This paper deals with the development and implementation of a current-source-converter-based static synchronous compensator (CSC-STATCOM) applied to the volt-ampere-reactive (VAR) compensation problem of coal mining excavators. It is composed of a plusmn750-kVAR full-bridge CSC with selective harmonic elimination, a low-pass input filter tuned to 200 Hz, and a Delta/Y-connected coupling transformer for connection to medium-voltage load bus. Each power semiconductor switch is composed of an asymmetrical integrated gate commutated thyristor (IGCT) connected in series with a reverse-blocking diode and switched at 500 Hz to eliminate 5th, 7th, 11th, and 13th current harmonics produced by the CSC. Operating principles, power stage, design of dc link, and input filter are also described in this paper. It has been verified by field tests that the developed STATCOM follows rapid fluctuations in nearly symmetrical lagging and leading VAR consumption of electric excavators, resulting in nearly unity power factor on monthly basis, and the harmonic current spectra in the lines of CSC-STATCOM at the point of common coupling comply with the IEEE Std. 519-1992

Enhanced Nationwide Wind-Electric Power Monitoring and Forecast System

This paper describes an enhanced monitoring and forecast system for the electrical power generated from wind in Turkey. Wind power plant (WPP) owners, transmission system operator, distribution system operators, and renewable energy experts are the shareholders of this system. The developed monitoring and forecast system is composed of wind electricity analyzers and reference wind masts, one for each WPP, a Wind-Electric Power Monitoring and Forecast Center (WPMFC) equipped with database, data processing, and application servers, and the associated monitoring and forecast software. All shareholders can communicate with the developed WPMFC in order to retrieve preprocessed wind-electric power forecast data and power quality data, through the IP network according to their authorization level. The electrical and meteorological raw data can also be retrieved for postprocessing. The developed system is based on global positioning system (GPS) synchronized, real-time field measurements taken from each WPP, in addition to the use of mesoscale numerical weather prediction models. Instantaneous electrical and meteorological quantities of each WPP can be monitored continuously through the WPMFC. The forecast system employs physical, statistical, and hybrid models combining both approaches. Some sample monitoring and forecast results are given in the paper to illustrate the benefits and abilities of the developed system.

National PQ Monitoring Network for Turkish Electricity Transmission System

In this paper a nationwide power quality monitoring system, which computes and collects PQ parameters and the required waveforms at a power quality monitoring center for both the purposes of early warning and later analysis of power quality of the whole transmission system, is presented. The system consists of three basic units: PQ monitors connected to various transformer substations all over the country; a national PQ monitoring center which communicates with all PQ monitors regularly, receives PQ data and archives them; and finally a client software, which lets individuals connect to the national PQ center and run searches on the PQ archive. The monitors compute PQ parameters based on the IEC Standard-61000-4-30. The client software will be available to the Electricity Transmission System Corporation of Turkey, TEIAS, distribution companies, large industrial plants which are directly supplied from the transmission system, research institutes and the universities. This is a three-year project of the Scientific and Technological Research Council of Turkey, TUBITAK, which started in March 2006 and the already-developed prototype system is presented in this paper.

Mobile Monitoring System to Take PQ Snapshots of Turkish Electricity Transmission System

This work is devoted to taking nationwide power quality (PQ) snapshots of the Turkish electricity transmission system, via field measurements carried out by application specific mobile monitoring equipment. This project is carried out as a subproject of the national power quality project of Turkey, and is aimed at investigating the general status of electric power quality and reactive power flows in the electricity transmission system all over the country. Critical points will then be selected to place permanent PQ monitors, and to carry out troubleshooting projects on the system. This paper describes the mobile monitoring system established, and the methodology used to obtain power quality snapshots of the Turkish electricity transmission system. Some sample outputs of the mobile monitoring system are also given in the paper.

Power Quality Solutions for Light Rail Public Transportation Systems Fed by Medium-Voltage Underground Cables

In this paper, the combination of a thyristor-switched shunt reactor and a current source converter-based active power filter has been proposed for mitigation of power quality (PQ) problems of Light Rail public Transportation Systems (LRTSs) fed by long medium-voltage underground cables. A case study has been carried out on a typical LRTS to assess the performance of the proposed solution for both capacitive reactive power compensation of underground cables and harmonic filtering of 12-pulse catenary rectifiers. It has been shown by extensive field tests carried out that this solution meets the requirements satisfactorily, thus constituting a complete solution to the PQ problems of LRTS. Conventional PQ solutions have been also assessed, and the corresponding theoretical results are given in comparison with the proposed system.

National Power Quality Monitoring network and assessment center for the Turkish Electricity Transmission System: Recent developments

In this paper, the National Power Quality Monitoring System, which is designed to monitor the power quality (PQ) of the Turkish Electricity Transmission System is presented. The National PQ Monitoring System consists of three main parts: PQ monitors, which are installed all over the country; a monitoring center, which collects the data sent by the power quality monitors in a database and provides assessment facilities; and a client software for remote connection to the center and analysis of the collected PQ data. PQ monitors compute the PQ parameters according to the IEC-Standard-61000-4-30. The PQ monitoring center is located in the TEIAS Ankara Bahcelievler campus and it has a huge digital light processing (DLP) display to observe the PQ events on the map of Turkey as soon as the event occurs. The client software provides remote connection from universities, research institutes and TEIAS offices to the monitoring center to analyse the collected PQ data. This is a three-year project which started in March 2006 To date, PQ monitor design has been completed. 9 monitors have been installed at various transformer substations in Turkey and the monitoring center is now collecting and displaying PQ data continously. 150 PQ monitors will have been installed by the end of the project all over the country and the PQ of the whole electricity transmission system will be monitored. Some measurement results obtained upto now are also presented in this paper.

Power quality solutions for Light Rail public transportation systems fed by medium voltage underground cables

In this paper, the combination of a Thyristor Switched shunt Reactor (TSR) and a Current Source Converter (CSC) based Active Power Filter (APF) has been proposed for mitigation of power quality problems of Light Rail public Transportation Systems (LRTS) fed by long medium voltage underground cables. A case study has been carried out on a typical LRTS to assess the performance of the proposed solution for both capacitive reactive power compensation of underground cables and harmonic filtering of 12-pulse catenary rectifiers. It has been shown by extensive field tests carried out that this solution meets the requirements satisfactorily, thus constituting a complete solution to the power quality problems of LRTS. Conventional power quality solutions have also been assessed, and the corresponding theoretical results are given in comparison with the proposed system.

A performance study on real-time IP multicasting

In this paper we investigate the performance of Internet group management protocol version 3 (IGMPv3) and real time transport protocol (RTP) for various scenarios. For this purpose, a network simulator is developed using C++. As it is important to evaluate protocol performances under realistic conditions, the simulation models and network traffic models that are used in the simulations are developed to reflect real life behavior. The simulation models are verified and the performance results obtained are compared with the past studies.