G. Bhuvaneswari

Design, Simulation, and Analog Circuit Implementation of a Three-Phase Shunt Active Filter Using the

A three-phase shunt active filtering algorithm based on the real component of fundamental load current (I cos Phi) has been proposed and implemented in a novel manner in this paper. The complete simulation and hardware implementation of the active filter (AF) with the proposed algorithm has been presented. Simulations have been performed for various dynamic operating conditions under balanced/unbalanced nonlinear reactive loads for both balanced as well as unbalanced/distorted source conditions. The AF has been realized by means of a hysteresis current-controlled voltage-source inverter (VSI). The experimental setup is controlled by making use of simple op-amp-based analog circuits and digital signal processor ADMC401. Experimental results have been obtained for different load and source conditions and discussed in detail. The response of the AF system in simulation as well as in hardware proves the effectiveness of the proposed control technique.

{\rm I}\cos\Phi

This paper presents the design, analysis, and development of a novel autotransformer-based 18-pulse AC-DC converter with reduced kilovoltampere rating, feeding vector-controlled induction-motor drives (VCIMDs) for power-quality improvement at the point of common coupling (PCC). The proposed autotransformer consists of only two single-phase transformers for its realization against three single-phase transformers required in other configurations. The proposed 18-pulse AC-DC converter is suitable for retrofit applications, where, presently, a six-pulse diode bridge rectifier is being used. A set of power-quality parameters, such as total harmonic distortion (THD) and crest factor of AC mains current, power factor, displacement factor, and distortion factor at AC mains, THD of supply voltage at PCC, and DC-bus-voltage ripple factor for a VCIMD fed from an 18-pulse AC-DC converter, are computed to observe its performance. The presented design technique provides flexibility to give an average DC output from the proposed converter, which is the same as that of a conventional three-phase diode bridge rectifier. However, it is also possible to step-up or step-down the output voltage as required. The effect of load variation on VCIMD is also studied to observe the effectiveness of the proposed harmonic mitigator. A laboratory prototype of the proposed autotransformer-based 18-pulse AC-DC converter is developed to validate the design and simulation model.

Algorithm

In this paper, a novel autotransformer with a reduced kilovolt-ampere rating is presented for harmonic current reduction in twelve-pulse ac-dc converter-fed vector-controlled induction motor drives (VCIMDs). Different transformer arrangements for 12-pulse-based rectification are also studied and a novel harmonic mitigator capable of suppressing fifth, seventh, and 11th (most dominant harmonics) in the supply current is presented. The design procedure for the proposed autotransformer is presented to show the flexibility in the design for making it a cost-effective replacement suitable for retrofit applications, where presently a six-pulse diode bridge rectifier is being used. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed harmonic mitigator. A set of power-quality indices on input ac mains and on a dc bus for a VCIMD fed from different 12-pulse ac-dc converters is given to compare their performance.

A Novel T-Connected Autotransformer-Based 18-Pulse AC–DC Converter for Harmonic Mitigation in Adjustable-Speed Induction-Motor Drives

Solar PV based electricity generation is gaining importance due to its abundant availability and improvements in materials and energy conversion technology. Global warming and fossil fuel depletion is indirectly catalyzing this transformation process. As the solar power conversion is already a low efficient conversion process, accurate and reliable modelling of solar cell is imperative to optimize the design of the solar PV system. Due to the non-linear nature of its characteristics, accurate modelling of a solar cell is still a difficult task. The existing models do suffer in a few issues while developing an integrated solar PV power conversion system. This paper compares two of the existing models for solar cell in MATLAB with a newly proposed model. To analyse and validate the results of the simulation models, I-V and P-V characteristics obtained from all the three models are compared with the experimental characteristics obtained from a 50W photovoltaic module. Finally relative merits and demerits of all the three models are discussed.

Harmonic mitigation using 12-pulse AC-DC converter in vector-controlled induction motor drives

In this paper, an autotransformer with reduced kilovoltampere rating for 24-pulse ac-dc converter fed vector controlled induction motor drives (VCIMDs) is presented for harmonic current reduction. The 24-pulse operation is achieved using dc ripple reinjection technique in 12-pulse ac-dc converters. The proposed novel harmonic mitigator is found capable of suppressing up to 21st harmonic in the supply current. The procedure for the design of autotransformer for proposed ac-dc converter is presented to show the flexibility in the design for making it a cost-effective replacement suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed ac-dc converter. A set of power quality indices on input ac mains and on dc bus for a VCIMD fed from other 24-pulse ac-dc converters are also given to compare their performance. The laboratory prototypes of proposed autotransformers based 12-pulse and 24-pulse ac-dc converters are developed and test results are presented to validate the developed design procedure and the simulation models of these ac-dc converters under varying loads.

Development of a solar cell model in MATLAB for PV based generation system

A new scheme for voltage regulation of standalone single phase self excited induction generator (SEIG) is proposed. The thyristor switched capacitor scheme with electronic controller is designed and implemented for the reactive power supply and voltage regulation of single phase two winding SEIG reported earlier [1-2]. The recorded waveforms and test results verify the correct and proper operation of all the sections of controller design as implemented in the laboratory. The object of this scheme is to provide a standalone single phase SEIG with acceptable voltage regulation with the help of inexpensive, simple thyristor switched capacitors, suitable for low power generator with single phase out put driven by any fixed speed prime mover such as an engine energized by oil or bio-fuel. The use of SEIG reduces the capital and maintenance cost of the system, while the electronic controller along with capacitors provides acceptable voltage regulation at its output terminal. Such a system is specially suited for portable/standby generator units of 1 to 10 kW rating. Experimental results demonstrate the viability of the scheme for practical deployment.

Pulse multiplication in AC-DC converters for harmonic mitigation in vector-controlled induction motor drives

This paper presents a novel configuration of an autotransformer based 18-pulse ac-dc converter for improving the power quality at the point of common coupling (PCC) in variable frequency induction motor drives (VFIMDs). The polygon based connection of autotransformer for achieving 18-pulse rectification is utilized to result in reduction in rating of the magnetics. The design of the autotransformer is carried out for an 18-pulse ac-dc converter feeding a vector controlled induction motor drive (VCIMD). Moreover, the autotransformer design is modified for making it suitable for retrofit applications, where presently a 6-pulse diode bridge rectifier is used. The effect of load variation on VCIMD is also studied and the performance of the proposed 18-pulse ac-dc converter is compared in terms of different power quality indices on both ac as well as dc side with other ac-dc converters. A laboratory prototype of the proposed autotransformer based 18-pulse ac-dc converter feeding a 10-hp induction motor drive is developed to verify the design and simulated results

A Novel Electronic Controller Implementation for Voltage Regulation of Single Phase Self-Excited Induction Generator

This paper deals with the pulse doubling in a 12-pulse ac-dc converter for improving power quality in vector-controlled induction motor drives (VCIMDs). The design of proposed magnetics shows the flexibility in varying the voltage ratio of the autotransformer for making it suitable for retrofit applications, where presently a six-pulse diode bridge rectifier is being used. The proposed ac-dc converter is capable of eliminating up to 21st harmonics in the supply current. The effect of load variation on VCIMD is also studied to demonstrate the effectiveness of the proposed ac-dc converter. A set of power quality indices on input ac mains and on dc bus for a VCIMD fed from proposed ac-dc converter are also given to compare its performance with six-pulse and twelve-pulse ac-dc converters.

A Novel Polygon Based 18-Pulse AC–DC Converter for Vector Controlled Induction Motor Drives

A new robust passive waveshaper based on 24-pulse ac-dc conversion is proposed to feed voltage source inverter (VSI) supplying squirrel-cage induction motor drive. The passive waveshaper consists of a newly designed T-connected autotransformer with less number of windings resulting in simplicity in design and manufacturing. The proposed 24-pulse ac-dc converter is found capable of suppressing less than 23rd harmonics in the supply current. The power factor is also improved to near unity in the wide operating range of the vector-controlled induction motor drive (VCIMD). Finally, the design of the autotransformer is modified to make it suitable for applications, where presently a 6-pulse diode bridge rectifier is used. A laboratory prototype of proposed T-connected autotransformer-based 24-pulse ac-dc converter is developed and test results are presented to validate the developed design procedure and the simulation models of this ac-dc converter under varying loads

Power-quality improvements in vector-controlled induction motor drive employing pulse multiplication in AC-DC converters

An HVDC transmission system has a converter transformer as one of its main components. The failure of the converter transformer is one of the major concerns for electric power utilities all over the world. Invariably, the top portions of the secondary windings of the converter transformers fail whereas the primaries are left unaffected. In this paper, an effort has been made to analyze the causes for these failures by means of modeling a practical HVDC system existing in India which ties up Talcher and Kolar and has a length of 1368 km. The modeling and analysis have been carried out in the MATLAB/SIMULINK environment. Based on the analysis, possible solutions for this problem have been suggested, such as providing passive filters on the secondary windings of the converter transformer, connecting a parallel capacitor on the dc side of the converter and R-C snubbers across the secondary windings. The suggested solutions have been compared to bring out their relative merits and demerits.