IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS, VOL. 43, NO. 1, JANUARY/FEBRUARY 2007 97 Reactive-Power Compensation of Coal Mining Excavators by Using a New-Generation STATCOM Hazim Faruk Bilgin, Student Member, IEEE, Muammer Ermis, Member, IEEE, K. Nadir Kose, Alper Cetin, Isik Cadirci, Member, IEEE, Adnan Acik, Turan Demirci, Alper Terciyanli, Student Member, IEEE, Cetin Kocak, and Mustafa Yorukoglu Abstract—This paper deals with the development and imple- mentation 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 ±750-kVAR full-bridge CSC with selective harmonic elimination, a low-pass input filter tuned to 200 Hz, and a Δ/Y -connected coupling transformer for connection to medium-voltage load bus. Each power semiconductor switch is composed of an asymmetrical integrated gate commutated thyris- tor (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 lag- ging and leading VAR consumption of electric excavators, re- sulting 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. Index Terms—Current-source converter (CSC), harmonic elimination, power quality, static VAR compensator (SVC). I. I NTRODUCTION E LECTRIC excavators, i.e., power shovels and draglines, are the key equipment in open-cast coal mining (Fig. 1). In addition to their intermittent character as a load on the network, they may be the sources of harmonics and consumers Paper PID-06-05, presented at the 2005 Industry Applications Society An- nual Meeting, Hong Kong, October 2–6, and approved for publication in the IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS by the Mining Industry Committee of the IEEE Industry Applications Society. Manuscript submitted for review October 15, 2005 and released for publication August 25, 2006. H. F. Bilgin, A. Cetin, T. Demirci, and A. Terciyanli are with the TUBITAK Information Technologies and Electronics Research Institute, TR 06531 Ankara, Turkey, and also with the Electrical and Electronics Engineering Department, Middle East Technical University, TR 06531 Ankara, Turkey (e-mail: faruk.bilgin@bilten.metu.edu.tr; alper.cetin@bilten.metu.edu.tr; turan. demirci@bilten.metu.edu.tr; alper.terciyanli@bilten.metu.edu.tr). M. Ermis is with the Electrical and Electronics Engineering Depart- ment, Middle East Technical University, TR 06531 Ankara, Turkey (e-mail: ermis@eee.metu.edu.tr). K. N. Kose and A. Acik are with the TUBITAK Information Technolo- gies and Electronics Research Institute, TR 06531 Ankara, Turkey (e-mail: nadir.kose@bilten.metu.edu.tr; adnan.acik@bilten.metu.edu.tr). I. Cadirci is with the TUBITAK Information Technologies and Electronics Research Institute, TR 06531 Ankara, Turkey, and also with the Electrical and Electronics Engineering Department, Hacettepe University, TR 06531 Ankara, Turkey (e-mail: cadirci@bilten.metu.edu.tr). C. Kocak is with Turkish Coal Enterprises, TR 06330, Ankara, Turkey. M. Yorukoglu is with Enerjisa Corporation, TR 34330 Istanbul, Turkey (e-mail: myorukoglu@enerjisa.com.tr). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TIA.2006.887308 Fig. 1. General view of the Southern Aegean open-cast lignite mining site (top: power shovels; bottom: dragline). of reactive power. The severity of power quality problems arising from electric excavators largely depend on their elec- tric motor drive technology: 1) Ward Leonard drives; 2) dc motor drives based on phase-controlled thyristor rectifiers; and 3) variable-frequency ac motor drives based on dc-link convert- ers. In newest excavators, device-commutated rectifiers have been used on the supply side of the dc-link converter system, thus providing theoretically harmonicless operation at nearly unity power factor [1]. The usual practice is to solve the power quality problems on each electric excavator individually. On the supply side, the use of overexcited synchronous motors, induction motors compen- sated by permanently connected shunt capacitors, permanently connected shunt filters, and thyristor-switched shunt filters are the most common solutions. However, in some of the applica- tions, the aforementioned solution techniques cannot provide an adequate reactive-power compensation, resulting in a need for group compensation of electric excavators [2]. In recent years, reactive-power compensation problem of coal mining equip- ment existing in the stocks of Turkish Coal Enterprises (TKI) has been solved by the use of unified relocatable static volt- ampere-reactive (VAR) compensators (SVC); each of which is composed of thyristor-controlled reactors (TCR) and shunt harmonic filters tuned to the fifth and seventh harmonics. The power quality problems are not new, but customer awareness of this problem has increased. In recent times, power quality issues and custom solutions have generated a 0093-9994/$25.00 © 2007 IEEE