Bikarma Singh

Fuzzy control algorithm for universal active filter

In this paper, a fuzzy algorithm is employed to control a three-phase unified power quality conditioner (UPQC). The UPQC is an active filter (AF) and it compensates the reactive power and harmonics in both the voltage and current caused by nonlinear loads. The UPQC makes use of two back-to-back connected IGBT-based voltage source inverters (VSIs) with a common DC bus. One inverter is connected in series while other is placed in shunt with the nonlinear load. The shunt inverter works as a current source and compensates current harmonics caused by nonlinear loads. The series inverter works as a voltage source and helps in compensating the voltage harmonics caused by nonlinear loads. A diode bridge rectifier feeding an R-L load is considered as a nonlinear current load while a source of voltage harmonics is considered in shunt with the load. With a view to examining the steady state and transient performance of the UPQC, a suitable mathematical model of the system is developed. The capability of the UPQC is demonstrated in the filtering of voltage and current harmonics along with the reactive power compensation of nonlinear loads. Simulated results are given and discussed in detail. Experimental results are also given.

Application of DSTATCOM for Mitigation of Voltage Sag for Motor Loads in Isolated Distribution Systems

This paper deals with one of the potential applications of distribution static compensator (DSTATCOM) to industrial systems for mitigation of voltage dip problem. The dip in voltage is generally encountered during the starting of an induction motor. Isolated distribution systems are comparatively not as stiff as grid systems; so large starting currents and objectionable voltage drop during starting of an induction motor could be critical for the entire system. DSTATCOM is one effective solution for isolated power systems facing such power quality problems. The model of DSTATCOM connected in shunt configuration to such an isolated system (3phase, 42.5 kVA alternator) feeding dynamic motor loads is developed using Simulink and PSB of MATLAB software. Simulated results demonstrate that DSTATCOM can be a considered as a viable solution for solving such voltage dip problems

A new control scheme of series hybrid active filter

This paper presents a digital implementation of a new and simple control technique of a hybrid filter to compensate harmonics of a nonlinear load. The hybrid filter consists of a shunt passive filter (PF) along with a series active filter (AF). A diode bridge rectifier with R-L load is considered as a nonlinear load. An indirect current controlled voltage source inverter (ICC-VSI) is considered as an AF. A simple control algorithm based on proportional plus integral control of a self-supporting DC bus voltage of the series AF is implemented on a TMS320C31 DSP. A laboratory prototype model of the proposed hybrid filter is developed and its performance is examined. Experimental results are given and discussed in detail.

A Survey of Ethnomedicinal Plants Utilized by the Indigenous People of Garo Hills with Special Reference to the Nokrek Biosphere Reserve (Meghalaya), India

The present study documented pharmaceutically important plant resources used in primary health care of ethnic Garo tribes from Eastern Himalayas (Nokrek Biosphere Reserve [NBR], India). In order to document information on medicinal plants and to maximize the collection of indigenous knowledge of Garo tribes, 12 traditional healers were identified using the Participatory Rapid Appraisal approach. Data were collected through open-end interviews with traditional healers, between 2007 and 2011. A total of 157 plant species representing 134 genera and 81 families were found to be commonly used in the treatment of 67 health-problems. More than one-fourth of the plant species were used in the treatment of cough, flu, and cold, which are prevalent ailments in the study area. The leaves, root, rhizome, and tuber were the most commonly used plant parts while decoction was the most common method of drug preparation.

A method of implementation of separating customer and supply side harmonic contributions using an active filter

This paper presents a scheme for implementing an approach to quantify the distortion caused by a single customer when there are many customers in the network, and then mitigate only that portion of harmonics for which the customer is responsible. Many complex theories have been proposed for sharing the responsibility but none suggests a practical way of implementing one such scheme. This paper makes use of the theory of conforming and nonconforming currents for sharing of responsibility which was earlier proposed by one of the authors. All the calculations are based on measurements during the operation and at the point of common coupling. The conforming current has the same graphical pattern as the voltage at point of common coupling. This is the responsibility of the utility. The balance of the current is nonconforming current and is the responsibility of the customer. In this paper, we present the results of simulation studies to demonstrate the feasibility of the approach. It has been demonstrated that the approach is successfully implemented using a digital-signal-processor (DSP) based active filter. The active filter (AF) is based on current controlled voltage source inverter.

Simultaneous quantitative determination of bioactive terpene indole alkaloids in ethanolic extracts of Catharanthus roseus (L.) G. Don by ultra high performance liquid chromatography–tandem mass spectrometry

Graphical abstract Figure. No caption available. HighlightsA UHPLC‐ESI–MS/MS method in MRM mode was developed and validated.Validation was based on calibration curve, linearity, LOD, LOQ and precision.UHPLC‐ESI–MS/MS method was successfully applied in ethanolic extracts of leaf, stem and root of 39 samples of C. roseus.Serpentine was detected as one of the most abundant alkaloid amongst 10 alkaloids.PCA was discriminated all C. roseus samples collected from five states of India. ABSTRACT A rapid, sensitive and reproducible method using ultra‐high‐performance liquid chromatography coupled with electrospray ionization hybrid triple quadrupole‐linear ion trap mass spectrometry (UHPLC‐ESI‐QqQLIT‐MS/MS) in multiple reaction monitoring (MRM) mode was developed and validated for simultaneous quantitation of anticancer (vincristine, vinblastine, vindesine), antihypertensive (ajmaline, ajmalicine, reserpine), aphrodisiac (yohimbine), sedative (serpentine) agents, dietary supplement (vinpocetine, yohimbine) and precursor of vinblastine (vindoline) from crude extracts of Catharanthus roseus. The precursor to product ion transitions for these compounds were observed at m/z 327 → 144, 355 → 144, 754 → 355, 353 → 144, 349 → 317, 825 → 225, 811 → 224, 458 → 188, 351 → 280 and 609 → 195, respectively in positive ionization mode. Chromatographic separation of all targeted TIAs was performed on ACQUITY UPLC BEH™ C18 column (1.7 &mgr;m, 2.1 mm × 50 mm). The calibration curves were linear within the concentration range 0.5–1000 ng/mL and correlation coefficients (R2) were closer to 1. Limit of detection (LOD) and limit of quantitation (LOQ) ranged from 0.039–0.583 ng/mL and 0.118–1.767 ng/mL, respectively. The intra‐day (0.23–2.71% RSD) and inter‐day (0.40–2.90% RSD) precision, stability (0.69–3.45% RSD) and recovery (99.63–104.30% ± %RSD ≤ 3.03%) were acceptable indicating good accuracy of the developed method. The method was successfully applied in ethanolic extracts of 39 samples of C. roseus parts (leaf, stem and root) collected from five different locations in India. Serpentine was detected as one of the most abundant TIA. Principal component analysis (PCA) was able to successfully discriminate among C. roseus samples on the basis of content of targeted TIAs.

Development of Ultra Performance Liquid Chromatography Tandem Mass Spectrometry Method for Simultaneous Identification and Quantitation of Potential Osteogenic Phytochemicals in Butea monosperma

An ultra performance liquid chromatography coupled with hybrid triple-quadrupole linear ion trap tandem mass spectrometry (UPLC-ESI-QqQLIT-MS-MS) method in multiple reaction monitoring mode was developed for identification and simultaneous determination of potential osteogenic compounds in ethanol extracts of different plant parts of Butea monosperma collected from different geographical regions. The chromatographic separation was carried out on an Acquity UPLC CSH C18 column (1.7 μm, 2.1 × 100 mm) with 0.1% (v/v) formic acid in water and methanol as mobile phase under gradient conditions in 8 min. The developed method was validated according to the guidelines of international conference on harmonization. The correlation coefficients of all the calibration curves were ≥0.9995 and recoveries ranged from 95.2 to 105.8% (RSD ≤ 1.95%). Relative standard deviations of intra-day, inter-day precisions and stability were ≤1.74, 1.84 and 2.8%, respectively. The quantitative results showed remarkable differences in the content of all potential osteogenic compounds in different parts of the plant as well as samples from different geographical regions. Quantitative variations studied from principal component analysis indicated tentative markers for B. monosperma cultivars which can discriminate sample of different geographical regions.

Assessment of chemical and genetic variability in Tanacetum gracile accessions collected from cold desert of Western Himalaya

Genetic diversity is essential for survival and adaptation of high altitude plants such as those of Tanacetum genus, which are constantly exposed to environmental stress. We collected flowering shoots of ten accessions of Tanacetum gracile Hook.f. & Thomson (Asteraceae) (Tg 1–Tg 10), from different regions of cold desert of Western Himalaya. Chemical profile of the constituents, as inferred from GC–MS, exhibited considerable variability. Percentage yield of essential oil ranged from 0.2 to 0.75% (dry-weight basis) amongst different accessions. Tg 1 and Tg 6 were found to produce high yields of camphor (46%) and lavandulol (41%), respectively. Alpha-phellendrene, alpha-bisabool, p-cymene and chamazulene were the main oil components in other accessions. Genetic variability among the accessions was studied using RAPD markers as well as by sequencing and analyzing nuclear 18S rDNA, and plastid rbcL and matK loci. The polymorphic information content (PIC) of RAPD markers ranged from 0.18 to 0.5 and the analysis clustered the accessions into two major clades. The present study emphasized the importance of survey, collection, and conservation of naturally existing chemotypes of medicinal and aromatic plants, considering their potential use in aroma and pharmaceutical industry.

Active corrector of the power factor in a three-phase network with impedance

This study aims to analyse the working of a three-phase convertor controlled by the method of pulse width modulation with sinusoidal references. A simulation aided by Matlab software is completed with consideration of the state representation of each working sequence. The values of the various parameters of the system is optimized on the basis of this simulation. It is then shown that this type of convertor can produce reactive power in order to restore the power factor to unity while continuing to operate as a voltage source. A closed-loop model control strategy is proposed and validated by simulation on Simulink. This control uses forward compensation and state return of the system linearized about the working point. The proposed forward compensation is based on a novel approach and leads to decoupling of the control on the two inputs to the system.

A Comprehensive Analysis of Vector Controlled Induction Motor Drive

The ruggedness of squirrel cage induction motor may be utilized by evolving an effective strategy for its speed control. In this paper, a control methodology for the current controlled voltage source inverter (CC-VSI) fed induction motor is considered. The proposed control strategy employs the concept of field orientation, also known as vector control. In the closed loop vector control of the motor, a PID speed controller and field weakening block are employed. With a view to studying the dynamic behaviour of the induction motor in the closed loop, its detailed model is developed. The model is made more realistic by taking the magnetic saturation into account. The simulated results showing the dynamic response of a vector controlled induction motor drive are presented and discussed. The proposed drive is useful for the applications where high dynamic performance is required such as rolling mill, hoist, traction etc.