Decision tree-based fault zone identification and fault classification in flexible AC transmissions-based transmission line

Transmission line distance relaying for flexible AC transmission lines (FACTS) including thyristor controlled series compensator (TCSC), STATCOM, SVC and unified power flow controller (UPFC) has been a very challenging task. A new approach for fault zone identification and fault classification for TCSC and UPFC line using decision tree (DT) is presented. One cycle post fault current and voltage samples from the fault inception are used as input vectors against target output dasia1psila for fault after TCSC/UPFC and dasia0psila for fault before TCSC/UPFC for fault zone identification. Similarly, the DT-based classification algorithm takes one cycle data from fault inception of three phase currents along with zero-sequence current and voltage, and constructs the optimal DT for classifying all ten types of shunt faults in the transmission line fault process. The algorithm is tested on simulated fault data with wide variations in operating parameters of the power system network including noisy environment. The results indicate that the proposed method can reliably identify the fault zone and classify faults in the FACTs-based transmission line in large power network.     

X-ray,electron microscopy and photovoltaic studies on CdTe thin films deposited normally at different substrate temperatures

X-ray diffraction, transmission electron microscopy and electron diffraction studies were conducted on CdTe thin films deposited on glass substrates kept at different substrate temperatures. Variation of the different structural parameters, such as lattice constant, crystallite size, r.m.s. strain, dislocation density and stacking fault probability with substrate temperature, was investigated in the temperature range 300 to 498 K. An increase in the lattice constant and crystallite size values and a decrease in the other parameters with increase in temperature of the substrate was observed. A photovoltage was observed for CdTe film deposited normally on glass substrates kept at higher substrate temperatures. The development of photovoltage in the film is explained in the light of the formation of crystallites of variable structure.     

Dehydration and phase transformation in chrysotile asbestos—A radial distribution analysis study

Radial distribution analysis of x-ray intensities diffracted by chrysotile samples untreated and treated at different temperatures upto 900°C has been carried out. Interatomic distances, coordination numbers, mean square displacements and the interatomic coupling constants for different pairs of atoms have been calculated from the radial distribution curves. The interatomic distances and octahedral co-ordination number is found to decrease marginally upto 640°C and thereafter decrease steadily upto 800°C. The hydroxyl water is completely expelled from the structure and the original chrysotile structure breaks down. The entire process of dehydration has been interpreted in terms of RDF data.     

Complex impedance analysis of layered perovskite structure electroceramics—NaDyTiO<Subscript>4</Subscript>

A ceramic oxide (NaDyTiO₄), having layered perovskite structure, has been prepared by a standard high-temperature solid-state reaction technique. X-ray diffraction (XRD) studies have confirmed material formation under reported condition along with the presence of impurity (Na₂Dy₂Ti₃O₁₀) as the minor phase. Complex impedance spectroscopy (CIS) analysis has been carried out to investigate its microstructure and electrical properties as a function of frequency and temperature. CIS analysis has indicated that the electrical behavior of the material sample shows negative temperature coefficient of resistance (NTCR) typical to a semiconductor. Impedance studies have also indicated the presence of temperature dependent relaxation process in the material with a spread of relaxation time. The d.c. conductivity of the material as evaluated from the impedance spectrum has been observed to be ∼10⁻⁹ Scm⁻¹ at room temperature (RT). It has been observed to increase as a function of temperature with a maximum of ∼10⁻⁵ Scm⁻¹ at 550∘C. The conductivity variation shows a cross over from Mott-type hopping phenomena at lower temperatures to a thermally activated Arrhenius type behavior at high temperature.     

Wavelet packet-based digital relaying for advanced series compensated line

A new approach for the protection of thyristor-controlled series-compensated (TCSC) line using wavelet packets transform (WPT) is presented. The proposed method uses one cycle post-fault-current samples just after fault inception, which is processed through WPT and decomposed into various decomposition levels. The decomposed components are grouped together to provide different frequency sub-bands. Then the phase selection signal (PSS) and section identification signal (SIS) are computed to identify the faulty phase and faulty section, respectively, involved in the fault process in transmission line including TCSC. A threshold value (THD) is selected for PSS, and PSS above THD describes the faulty phase involved, otherwise not. Similarly, another THD is selected for SIS, and SIS below THD describes fault that includes TCSC, otherwise fault that does not include TCSC. As PSS takes half cycle after fault inception to identify the faulty phase and then triggers SIS, the faulty phases and faulty sections are identified within one cycle of fault inception. The proposed WPT algorithm is also tested on physical transmission line model with TCSC, under wide variations in operating conditions and provides accurate results. Thus, the proposed method provides accurate and fast protection measures for TCSC-based line.     

Transmission line distance relaying using a variable window short-time Fourier transform

This paper presents a new approach for transmission line protection using a variable window short-time Fourier transform known as S-transform. The S-transform (ST) is a time–frequency spectral localization method, similar to short-time Fourier transform (STFT), but with a Gaussian window whose width scales inversely, and whose height scales linearly with the frequency. The change in spectral energy of the ST of the current and voltage signals provide the information regarding fault detection. After the fault detection, the impedance to the fault point is calculated using the estimated phasors of the faulted current and voltage signals which provide accurate results even with noisy conditions. Also, the fault location is calculated using polynomial curve fitting technique with a devised index obtained from the ratio of spectral energy of the voltage and current signals, respectively.     

Performance and Emission Analysis of a Novel Porous Radiant Burner for Domestic Cooking Application

Present study focuses on the performance and emission analysis of a novel porous radiant burner for domestic cooking application using liquefied petroleum gas (LPG) as fuel. The porous radiant burner (PRB) used here is a novel ceramic porous radiant burner which is designed and developed in the University laboratory for this present study. Two kinds of PRBs as circular porous radiant burner and square porous radiant burner have been developed and hence the thermal efficiency and emission analysis of these burners are tested for their performance. The test results are very encouraging as the thermal efficiency of the circular porous radiant burner and square porous radiant burner are much higher as compared to the conventional metallic burners or other types of burners. The emission characteristic also shows that the emission of CO and NOx values are much lesser than the conventional burner and are well within the world health organization standard. The experimental setup used here is a flexible one that contains PRBs, LPG cylinder, K- type thermocouple, data acquisition system, flue gas analyzer, Infrared camera and a computer. The maximum thermal efficiency obtained in that test for the PRB is about 72% which indicates its bright future prospect.     

A critical comparison of various data processing methods in simple uni-axial compression testing

The paper compares the error associated with various data processing methods to obtain true stress–plastic strain data from the load–deformation curves generated from uni-axial compression tests. Towards this end, uni-axial compression tests have been conducted on three representative materials viz. modified 9Cr–1Mo ferritic steels, alloy D9 (a titanium modified austenitic stainless steel) and 316L(N) austenitic stainless steel in wide ranges of temperatures and strain rates. It has been observed that the absolute average error associated with maximum true plastic strain calculation in all the three materials is always more than 5% and sometimes as high as 42.1% if the elastic region is removed either from the load–stroke curve or engineering stress–strain curve to get the true stress–plastic strain curve. However, the absolute average error associated with plastic strain calculation is always less than 5% if the elastic region is removed from the true stress–strain curve.     

Phosphomolybdic acid dispersed in the micropores of sulfate treated Zr-pillared clay as efficient heterogeneous catalyst for the synthesis of β-aminocarbonyl compounds in aqueous media

Zr-pillared clay (Zr-P) was synthesized by insertion of zirconium oxyhydroxy clusters into clay interlayer and subsequent thermal activation. The Zr-P materials were treated with sulfuric acid to graft sulfate ions onto the zirconia nanopolliars. The sulfate grafted Zr-Pillared clay (SZr-P) was used as support for phosphomolybdic acid (PMA/SZr-P). The synthesized materials were characterized by XRD, IR, UV–Vis, SEM and sorptometric techniques. The expansion of the clay lattice as a result of pillaring was confirmed from X-ray diffraction study. The interlayer space was found to be retained in the PMA/SZr-P material. All pillared clay materials show Type-I sorption isotherm typical of microporous materials. The IR spectra of the pillared clay materials show the presence of acidic and non-acidic hydroxyl groups. The structural integrity of the phosphomolybdic acid in the clay matrix was ascertained from the IR and UV-Vis spectroscopy. The PMA/SZr-P material was used as an efficient catalyst for the one pot synthesis of β-aminocarbonyl compounds by Mannich reaction in aqueous media. The multicomponent condensation of aryl aldehyde, amines and ketones using PMA/SZr-P material afforded a variety of β-aminocarbonyl compounds in excellent yield and purity under ambient conditions. The protocol developed in this investigation using the PMA/SZr-P material was found to be advantageous in terms of simple experimentation, preclusion of toxic solvents, recyclable catalyst and high yield and purity of the products.