B. Gultekin

Multi-DSP and -FPGA-Based Fully Digital Control System for Cascaded Multilevel Converters Used in FACTS Applications

In this paper, a fully digital controller based on multiple digital signal processor (DSP) and field-programmable gate array (FPGA) boards has been proposed for parallel-operated cascaded multilevel converters (CMC) used in flexible AC transmission system (FACTS) applications. The proposed system is composed of a DSP-based master controller in combination with a multiple number of slave DSP boards, FPGA boards, microcontrollers, a programmable logic controller (PLC), an industrial computer, and their peripherals in interaction. Intercommunication of these digital controllers is achieved mainly through fiber-optic links, via synchronous serial data link wherever a high-speed, full duplex communication is needed, and via asynchronous serial communication interface wherever relatively slow communication speed is required. The proposed fully-digital control system has been implemented on a sample 11-level CMC-based 154-kV, +/-50-MVAr transmission type static synchronous compensator (T-STATCOM). Field test results have shown that the proposed fully digital control system provides good transient response and steady-state characteristics for the oveall system including protection and monitoring functions.

Design and Implementation of a 154-kV

In this research work, the design and implementation of a 154-kV ± 50-Mvar transmission static synchronous compensator (T-STATCOM) have been carried out primarily for the purposes of reactive power compensation and terminal voltage regulation and secondarily for power system stability. The implemented T-STATCOM consists of five 10.5-kV ±12-Mvar cascaded multilevel converter (CMC) modules operating in parallel. The power stage of each CMC is composed of five series-connected H-bridges (HBs) in each phase, thus resulting in 21-level line-to-line voltages. Due to modularity and flexibility of implemented HBs, each CMC module has reached a power density of 250 kvar/m3, thus making the mobility of the system implementable. DC-link capacitor voltages of HBs are perfectly balanced by means of the modified selective swapping algorithm proposed. The field tests carried out at full load in the 154-kV transformer substation where T-STATCOM is installed have shown that the steady-state and transient responses of the system are quite satisfactory.

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In this research work, design and implementation of a 154 kV, ± 50 MVAr Transmission STATCOM (T-STATCOM) has been carried out primarily for the purposes of reactive power compensation and terminal voltage regulation, and secondarily for power system stability. The implemented T-STATCOM consists of five 10.5 kV, ±12 MVAr Cascaded Multilevel Converter (CMC) modules operating in parallel. The power stage of each CMC is composed of five series connected H-Bridges (HB) in each phase, thus resulting in 21-level line-to-line voltages. Due to modularity and flexibility of implemented HBs, a CMC module power density of 250kVAr/m3 is reached, thus making the mobility of the system implementable. DC link capacitor voltages of HBs are perfectly balanced by means of the Modified Selective Swapping Algorithm proposed. The field tests carried out at full load in the 154 kV transformer substation where T-STATCOM is installed and put into service have shown that the steady-state and transient responses of the system are quite satisfactory.

50-Mvar Transmission STATCOM Based on 21-Level Cascaded Multilevel Converter

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.

Design and implementation of a 154 kV, ±50 MVAr Transmission STATCOM based on 21-level Cascaded Multilevel Converter

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.

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

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

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

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.

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 ETI Aluminium Works. 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. 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 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.

Power quality solutions for 12-pulse smelter converters in ETI Aluminium Works

This paper is devoted to the design and implementation of a 12-pulse thyristor controlled reactor (TCR) system, which constitutes a low-cost solution to the reactive power compensation problem of a ladle furnace in Iskenderun iron and steel plant (ISDEMIR). Design objectives and elimination of 5th and 7th harmonic current components produced by 6-pulse TCRs are met by connecting two sets of 6 kV, 6 MVAr TCRs to the 34.5 kV ladle furnace bus by the use of two separate converter transformers with delta- and wye-connected secondaries. The effects of dissimilarities between the two sets of 6-pulse TCRs on the harmonic current content of the resulting 12-pulse TCR system are also presented in this paper. Both reactive power compensation and power system redundancy objectives are met by using two separate and dissimilar transformers instead of a single transformer with identical /spl Delta/-and Y-connected secondaries for connection to 6-pulse TCRs, resulting in a two-folded design. One of these transformers is chosen as a sufficiently large unit with two identical /spl Delta/-connected secondaries to supply the ladle furnace in emergency or during maintenance periods of main transformer. In normal operation mode of the resulting ladle furnace power system, the 12-pulse TCR implemented in the project gives quite satisfactory results in reactive power compensation and nearly meets harmonic standards currently used in the country.