Design and Implementation of a Current-Source Converter for Use in Industry Applications of D-STATCOM

This paper deals with the design and implementation of the power stage of a forced-commutated current-source converter (CSC) for use in industry applications of distribution type static synchronous compensator (D-STATCOM). The power semiconductors are switched at 500 Hz according to the switching patterns generated by selective harmonic elimination method for the elimination of the most significant four low-order harmonics. The possibility of using various power semiconductors in CSC is examined both theoretically and experimentally. The requirement of bipolar voltage-blocking capability is achieved by the use of an asymmetric integrated gate commutated thyristor (IGCT) and a fast-recovery diode instead of a single symmetrical device, which maximizes the converter power rating and makes natural-air cooling realizable. Determination of optimum dc-link reactor in view of the power quality standards and design of optimum turn-ON and turn-OFF snubbers in view of the chosen power semiconductor characteristics are shown to be critical design issues in the paper. Design principles are verified by both laboratory tests and field tests conducted on two different industrial D-STATCOM prototypes. It has been shown that an IGCT-based CSC can be successfully used in industry applications of D-STATCOM systems by designing the power stage according to the proposed principles

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

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 +/- 750-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