B. Kishore Kumar

Bio: B. Kishore Kumar is an academic researcher from VIT University. The author has contributed to research in topics: Variable-frequency drive & Converters. The author has an hindex of 1, co-authored 1 publications receiving 4 citations.

Design and Analysis of Electrical Drives Using Active Front End Converter

Abstract: Variable frequency drives are widely used nowadays mainly because of their efficiency and reliability characteristics. Insulated Gate Bipolar Transistor active front end converters are frequently used because they offer a number of advantages such as bidirectional power flow, filter size is small, unity power factor and reduced harmonic distortion. IGBTs have unique attributes which allow VFD to actively control the power input, making it tolerant of supply side disturbances. This paper shows a MATLAB Simulink model which analyses the performance of a VFD and its control using AFE based variable frequency drive for induction motor used for crane drives in mining operations.

Symmetrical Components Detection With FFDSOGI-PLL Under Distorted Grid Conditions

Abstract: To synchronize grid-connected voltage source inverters with the grid, the knowledge about the phase angle of the fundamental, positive sequence of the supplying voltage is necessary. For additional compensation tasks, the knowledge about all symmetrical components is needed as well. A DSOGI-PLL (dual second order generalized integrator - phase locked loop) provides a method to determine the phase angle in a notable manner. Because of a co-dependency between the DSOGI and the PLL through its estimated frequency, the speed of the PI controller is limited. A solution is to set a fixed value as tuning frequency with recalculation of the resulting errors. This paper offers a method based on a frequency-fixed DSOGI-PLL to calculate the phase angle and the symmetrical components of the supplying voltage with high damping of harmonics which are inherent in it, in a fast and stable way.

The Comparative Analysis of Processes in Active Front End (AFE) for Cases of Different Power Sources

Abstract: The article presents the comparative analysis of influence of different power sources connected to an active front end on processes in the supply grid of limited capacity. The mathematical model of an active front end control system for cases with different power sources (generators) is developed and analyzed. The algorithms of forming generic control system of active front end are described and analyzed. The results show that power sources, such as ideal DC power source, battery and induction motor in the slip power recovery mode, have almost similar power quality characteristics It allows using simpler methods of power supply system analysis in case of presence of additional power sources based on active front end.

Description of processes in an active front-end with a fourth branch

Abstract: Neutral wire is used in multiple active front-end application. Some of these applications are single phase loads and maintaining system stability in case of emerging unsymmetrical components, which can lead to malfunction and device failure. In such cases neutral wire potential can be middle point of DC-link, what leads to capacitor separation, but also can be implemented as additional arm, leading to full DC-link voltage utilization and additional control channel for zero symmetrical component in case of unsymmetrical load. In order to perform control system synthesis for such a complicated object, knowledge of its complex mathematical model is required. Four arms active front-end mathematical model is developed for analysis and control system development, featuring phase-coordinates usage and taking into account multiple peculiarities of this converter. Diagrams of main voltages and currents components are derived from model research.

Negative Impact Mitigation on the Power Supply System of a Fans Group with Frequency-Variable Drive

Abstract: The technological installations’ characteristics are possible to improve by equipping fans with a frequency-controlled electric drive. However, it can lead to an electromagnetic compatibility problem in the electrical supply system. This problem becomes worse if a large number of fans are included in the technological installation and the electric drives are powered from a substation connected to a limited power source. As an example, in this article we investigate the power supply system of a gas cooling unit with variable-frequency electric drives for fans. The electric drives’ operating mode dependences characterizing the non-sinusoidal voltages and currents of the power source are obtained with the help of simulation modeling in the MATLAB environment with the Simulink expansion package. The typical substation circuit usage for the power supply of a group of fans with a frequency-controlled drive does not meet the requirements of IEEE Standard 519-2014. We can solve the problem of electromagnetic compatibility by changing the substation topology and organizing DC busbars and replacing frequency converters with inverters. We proposed forming DC busbars using 12-pulse rectifiers powered by transformers with two secondary windings with different connection schemes. The simulation results confirmed that the proposed substation topology provides the voltage and current harmonics level on the substation power busbars in accordance with the IEEE Standard 519-2014 requirements over the entire frequency range of the fans’ motor control.

Experimental Studies of Power Quality in the 34.5 kV Network of MMK Metalurji During Operation of Electric Drives with Active Rectifiers

Abstract: Medium voltage distribution networks of 6 - 35 kV are used in in-plant power supply systems in steel mills. As a mutual influence result of the capacitances of long cable lines and the inductances of step-down transformers, resonance phenomena can occur in the medium frequency range. If the high-frequency harmonics generated by frequency converters with active rectifiers fall into the resonant range, this can lead to disturbances in the plant’s internal distribution network. Such phenomena can cause long downtime of technological equipment and product defects. This entails significant economic losses, especially in the production of high value-added products. This paper reflects the experimental research results of voltage quality in 34.5 kV distribution networks of metallurgical plant “MMK Metalurji”. Measures for electromagnetic compatibility improvement of frequency converters with active rectifiers of electric drives in hot strip mill 1750 with supply mains are proposed.