A. Terciyanli

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

A Selective Harmonic Amplification Method for Reduction of kVA Rating of Current Source Converters in Shunt Active Power Filters

This paper describes a new approach to the design of current-source converter (CSC)-based shunt active power filters (APFs) to reduce the converter kilovolt-ampere rating considerably. This design approach is called the selective harmonic amplification method (SHAM), and is based on the amplification of some selected harmonic current components of CSC by the ac-side filter, and the CSC control system specifically designed for this purpose. The proposed SHAM has been implemented on a CSC-based APF for the elimination of 11th and 13th current harmonics of 12-pulse rectifier loads supplied from a medium-voltage underground cable. Simulation and field test results have shown that SHAM can successfully be applied to a CSC-based APF for reduction of the converter kilovolt-ampere rating, thus making it a cost-competitive alternative to voltage-source-converter-based APFs traditionally used in industry applications.

A Current Source Converter-Based Active Power Filter for Mitigation of Harmonics at the Interface of Distribution and Transmission Systems

A medium power Current Source Converter (CSC) based Active Power Filter (APF) system is designed and implemented to suppress the amplification of low order harmonics at the Medium Voltage (MV) interface bus between the distribution and transmission systems, owing to the presence of large shunt capacitor banks installed only for reactive power compensation. For this purpose, four CSC based APF units designed at 1.0 kV are operated in parallel, and connected to the 31.5 kV MV bus via a specially designed coupling transformer. In each APF module, a specially designed LC-type input filter eliminates the switching ripples, and active damping method embedded into the control software suppresses harmonic frequencies around the natural frequency of the input filter. The resulting system can operate at relatively high frequencies in the range from 2.0 to 3.0 kHz, depending upon which selected harmonics among 5th, 7th, 11th, and 13th are to be eliminated. Furthermore, in order to reduce the installed capacity of CSCs, Selective Harmonic Amplification Method (SHAM) is applied to the APF system described in the paper. MV APF system has been built as a mobile system for temporary connection to a problematic MV interface bus, until a permanent solution is found for that location in the distribution system.

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.

Reactive Power Compensation of Coal Conveyor Belt Drives by Using D-STATCOMs

This paper discusses feasibility of conventional and fully static reactive power compensation techniques used in the solution of power quality problems of coal conveyor belt drives and also describes the features and field performance of the distribution type static synchronous compensator (D-STATCOM) prototypes in such applications. They are composed of 2-level, 3-leg voltage/current source converters (VSC/CSC), low-pass input filters and Delta/Y connected coupling transformers to allow their connection to medium voltage load bus. Reactive power is controlled in both capacitive and inductive regions by phase-shift-angle control. Dominant voltage/current harmonics of VSC/CSC are eliminated by selective harmonic elimination method (SHEM). Developed D-STATCOMs are shown to comply with IEEE Std 519-1992 even for the weakest supply. Viability of D-STATCOM in reactive power compensation of conveyor belts has been proven in the field.

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.

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 VAr compensation problem of coal mining excavators. It is composed of a /spl plusmn/750 kVAr full-bridge current source converter with selective harmonic elimination, a low-pass input filter tuned to 200 Hz, and a /spl delta//Y connected coupling transformer for connection to medium voltage load bus. Each power semiconductor switch is composed of an asymmetrical IGCT connected in series with a reverse blocking diode and switched at 500 Hz to eliminate 5/sup th/, 7/sup th/, 11/sup th/, and 13/sup th/ current harmonics produced by CSC. Operating principles, power stage, and design of DC link, and input filter are also described in the 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 pf on monthly basis, and the harmonic current spectra in the lines of CSC-STATCOM at the point of common coupling comply with IEEE Std. 519-1992.

A unified relocatable SVC for open-cast lignite mining in Turkey

Design and implementation of a unified, relocatable static VAr compensator (SVC) meeting reactive power compensation needs of various coal enterprises of Turkey for open-cast lignite mining have been presented. Design and sizing of SVCs are based on mains data for all possible connection points, load bus data recorded in the field, monthly electric bills and simulations carried out on PSCAD/EMTDC, SPICE and MATLAB. In addition to standard AC/DC converter and motor tools used in the modeling of electric excavators, actual load characteristics obtained from data collected in the field by means of a data acquisition system have been processed in PSCAD/EMTDC to rind out reactive power demand of each load bus, and to optimize sizing of SVC within the power factor penalty limits imposed by electricity authorities. The SVC component ratings have been based upon the suitability to all possible loads under worst operating conditions, thus making sure that they can be operated for different loading conditions, minimizing stock requirements, and inspection and maintenance costs. The implemented systems are flexible and extendable in order to meet the future needs of coal enterprises.

Power quality solutions for 12-pulse smelter converters in ETI aluminum works

This paper describes the solution of power quality problems arising from 12-pulse smelter converters in the ETI Aluminum Works, Seydis

A Current Source Converter based Active Power Filter for mitigation of harmonics at the interface of distribution and transmission systems

80ehir, Turkey. The design work is based on practical data collected in the field as well as on the results of detailed simulation studies obtained by EMTDC/PSCAD, SPICE, and MATLAB. The main design objective is to meet both present regulations and harmonic standards by using robust, reliable, and cost-effective systems with a long life expectancy. The shunt-connected passive reactive power compensation system is composed of a damped 11th harmonic filter and a make-up filter tuned to the 5th harmonic with optional damping resistor. Such a system exhibits nearly transient-free switching and series-resonance proof characteristics owing to damping resistors. A close correlation has been obtained between theoretical results and field data.