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Power transformer is one of the most important high voltage apparatus in any power system network. The life span of such apparatus commonly relies upon its insulation condition. The primary reason for an insulation breakdown is partial discharge. Partial discharges (PDs) are electrical discharges that happen in the insulation system of the transformers. Occurrence of PDs results in deterioration of the transformer insulation system. Hence, measuring and detecting the PD at an initial stage is necessary to avoid complete breakdown of the transformer. Currently, various PD detection and measurement methods, such as, electrical, chemical, acoustic, UHF and optical methods are being used for PD monitoring in power transformers. The conventional PD monitoring techniques like electrical or chemical have some limitations. The optical Fiber Bragg Grating (FBG) Sensor has been used as a PD sensor for PD monitoring in the power transformer to overcome these issues. This paper presents a review of FBG sensors’ application as a sensor for PD monitoring in an oil-filled power transformer. The challenges and future prospects in this area are also discussed.

Energy policymakers address rural energy poverty with locally available renewable sources. Further, an acquaintance in the adoption of similar renewable based rural electrification technology (RBRET) would enhance the community acceptance in the neighboring villages. As a result of which, the pace of RBRET dissemination can be heightened in the corresponding geographic cluster. Amongst the varied RBRET projects, Micro Hydro Power (MHP) is relatively economic, efficient, reliable, and ease to operate. However, the sustainability of MHP cluster relies upon the appropriate prioritization process of site selection. In this regard, a novel computational intelligence technique has been proposed through a case study in the eastern Himalayan region of India. The proposed model encompasses four phases. First, refinement of the initial technical feasibility conformations through geographical information system (GIS) and past hydrological data. Second, the establishment of interdependency influencing relationship using interpretive ranking process (IRP). Third, the computation of Pareto based prioritization of entropy weights derived through IRP. Fourth, the prioritization of potential sites for MHP in the sequential manner adopting fuzzy similarity analysis measure, and Ardalan heuristic method. The proposed hybrid model surpasses the existing application of standalone methods such as multi-criterion analysis tools, geographic information system, and econometric analysis method.

Most Electric Power Exchange (PX) around the world employs Linear Programming (LP) based method for step-wise market clearing in Day-Ahead Electricity Market (DAM). Market clearing involves calcul...

This study provides an overview of the different techno-commercial aspects of a wind energy conversion system. The review includes the grid codes provided by the transmission system operator of different countries supplemented by various communication protocols, explanation of different types of conventional and advanced wind generators, discussions on different maximum power point algorithms along with various conventional and advanced pitch angle control systems. The study also describes a variable speed system using different types of power electronic converters at the generator and the grid side to maintain power quality, grid synchronisation and unity power factor operation along with various cooling techniques utilised. In a subsequent part, a clear overview of different control topologies such as field-oriented control, direct torque control, voltage-oriented control and direct power control has been provided along with the recent advancement of each and every topology. The study also provides the challenges of the prevailing technology along with the already available and possible ways of minimising these technological gaps. Finally, a techno-commercial comparison of different commercially available wind systems by different companies has been presented along with their market share based on the current scenario.

Owing to rapid depletion of fossil fuels and environmental hazard, different non-conventional sources of energy like wind, geothermal, nuclear, photovoltaic etc, have been taken into consideration for power generation. Environmental familiarness, reduced installation cost, improved power quality, abundant availability of source makes photovoltaic based distributed generation as one of the most popular alternative source of energy production. Improvement in power electronics technology makes synchronization of PV system with grid more viable. Power output from the PV module changes continuously with time depending upon the climatic condition. In order to get maximum output from the PV system different types of MPPT algorithm present in literature are studied and improvement proposed are described in this paper. Furthermore, different types of inverter topologies along with different grid synchronization technique and PWM topologies used to connect the PV system with the 3-phase AC grid are presented. In order to minimize the harmonic content of the inverter output, different types of filters used are presented in the proceeding section. Nextly different commonly used advanced islanding detection techniques for the safety purpose of PV based distribution generation system have been addressed and based on advantages and limitation of anti-islanding techniques, a comparison table has been presented. Afterward based on parameters like input, output voltage & current, MPP range, used standards etc, a comparison table between different commercially available grid tied PV inverters are presented in this paper. Finally, drawbacks of the prevailing grid connected PV system have been discussed.

Presently the insulation used in the majority of electric utility transformers generally consists of cellulose materials impregnated with mineral oil. But, conventional mineral oil has long been recognized as hazardous to the environment and also being derived from crude oil – a non-renewable source, and hence, over the last few decades, insulating oil from a renewable source has been researched due to their high environmental and fire safety features. However, vegetable insulating oils are still 2–3 times more expensive, and therefore, new vegetable oils not used so far in transformers have also been experimented with by some researchers. Jatropha Curcas oil is one such example. The plant of Jatropha Curcas is extensively spread all over the tropical and sub-tropical countries and adapted to harsh environmental conditions. In this paper, a comparative review of Jatropha Curcas-based insulating oil has been presented based on the experimental results from the previous studies, perspective on the current status and future development needs are discussed.

Close Proximity Operation of HVAC and HVDC transmission line is the recent trend for increase of power transmission capacity. Need for same is becoming vital day by day due to ever increasing power demand. Erection of HVAC lines has a requirement of high right of way (ROW) as compared to the HVDC lines. Also recent past has witnessed constraint in availability of ROW for many projects of Indian Power Grid. Raise in transmission voltage level of HVDC from Power Grid Corporation of India Limited (PGCIL) and its suitability to decentralized non-conventional grids has led to addition of many upcoming HVDC projects with the already existing ones. So the need of analysis for electric field distribution under this type of hybrid transmission corridor is necessary to meet the standards of engineering design, exposure limits to living beings and environmental protection. The present work shows a two dimensional modelling approach for estimation of hybrid electric field at ground surface with impulse excitation. A practical case of hybrid transmission corridor so formed in Northeast Agra HVDC project of PGCIL has been taken for this case. Effects of both standard and non-standard impulse waveform has been modelled and analysis of its effect on hybrid electric field is presented.

Abotani community of eastern Himalayan region have been recognized as one the ethnic groups with comprising of many tribes of same antecedent. Their old scientific management of natural resources through their indigenous belief and practice system. The traditional knowledge of the community, though has not been recorded in the writing format, has been preserved by passing the knowledge from one generation to another generation by word of mouth and daily need-based practices. The paper highlights the inter-relationship between indigenous community-based beliefs and practicing cooperation and management of natural resources and farming practices for many centuries. preserve and scientific agroforestry approaches such as The Abotani community has also been involved in community management practices like Kebang, Kabo,Soru-Ruth, Rongo-Ray, Aka Mele, Buling. The paper has emphasized the similarity with that of present days' village community management system and modern. Finally, the paper has attempted to focus on the success story of a commercially viable cooperative farming.

The effective and efficient utilization of electrical energy is the outcome of smart energy management system. Moreover, appropriate augmentation of renewable energy alternatives through distributed generation can considerably unburden the power utility system. This paper identifies the scope for the rule based approach to develop an energy efficient utilization model for bulk power consumers. The augmentation of distributed power generation using solar PV has also been proposed which considerably reduces the maximum demand (M.D) of power during peak hours. The distributed generation from solar PV for this case-study uses minimum storage battery as the generation schedule and the load schedule often coincides. The portfolio of energy distribution is formulated based on priority of energy demand. The proposed model can be suitably modified for similar type of load centers including industrial loads.

Summary Impulse voltage testing is generally carried out for assessing the insulation strength of power equipment using standard impulse voltage waveforms in high-voltage laboratory. However, in actual field, the power equipment experiences standard and non-standard lightning impulse voltages. The main objective of this work is to analyse the voltage stress on surge arresters under standard and non-standard lightning impulse waveforms. Surge arrester models are developed in matlab (The MathWorks, Inc., Natick, Massachusetts, United States), and residual voltage test results are compared with manufacturer data for validation. Impulse voltage test is performed on the Institute of Electrical and Electronics Engineers surge arrester model using standard and non-standard lightning impulse voltage waveforms. The obtained test results showed that non-standard impulses have the potential to develop higher voltage stress and hence pose a high risk to surge arresters. However, results of this study provide the basis for further laboratory-based investigation considering a wide variety of impulse voltage waveforms representing the real lightning overvoltages. The test results will contribute to identify the need for modifying existing test standards or introducing new standards for impulse testing of surge arrester. Copyright © 2015 John Wiley & Sons, Ltd.

This work presents an extension of our previous work on voltage stress analysis of a 3 MVA, 33/11 kV, 3-phase, 50 Hz, Dyn 11 transformer against the application of standard and non-standard impulse voltages. A preliminary comparative study on the variation of maximum voltage to ground and voltage across the coils under different impulse voltages indicated that non-standard impulse voltage waveforms develop higher voltage stress in the windings. They pose high risk and are critical to transformer insulation system. The obtained test results provide the basis for further study of non-standard impulse voltage waveforms and make necessary correction in the existing impulse testing standards. However, to take care of the stringent effect of actual lightning and other impulse voltages occurring in practical field a more detailed study considering a wide variety of non-standard impulse voltage waveforms is aimed to be done in future.

Pulsed Power in the form of Recurrent Surge Generator (RSG) can be used for testing various parameters of Motor or Transformer windings including inter turn, interlayer insulation and many other winding defects. In motor and dry type transformers insulation has many interfaces and undesirable defects and these defects can be exposed under this non destructive testing methodology. With the development of power electronics variable frequency drives (VFD), Dry Type or cast resin Transformers used with PWM Sine wave inverters for solar power are being widely used. Solid insulation system used now-a-days are shifting more and more to high frequency applications. To probe the integrity of the Electrical insulation system as well as winding defects we have used the recurrent surge generator for testing winding integrity as well as Partial Discharge(PD) at fast rising voltage enabling PD measurement at closer situation under which the insulation system is supposed to work. We have discussed test results on different system with recurrent surge voltages of different rise time.

In this paper, the Simulated Annealing (SA) optimization method is introduced to estimate the parameters of Fractional Order Proportional-Integral-Differential (FOPID) controller for controlling a field-controlled DC servo motor. The parameters are evaluated for considering a transfer function of controlling a field-controlled DC servo motor and its performance is observed for unit step response. Also, the parameters of FOPID controller are calculated using the traditional techniques such as Genetic Algorithm (GA) and frequency domain design method based on constrained optimization for the sake of comparison of performance with respect to simulated annealing method. A detail study on all the specified techniques is discussed in this paper.

Customer’s view in online brand community acts as a foundation for the co-creation of the brand, which results in increased purchase frequency. Influencing attributes as the independent variables significantly influences performance of these online platforms. Prioritization of these alternative platforms would act as a boosting factor for marketer for their inclusive growth. In this paper, an attempt has been made with the help of interval type-II fuzzy multiple group decision making process for the said purpose. A fuzzy linguistic interpretation membership has also been proposed which can further improve the computed results.

Eastern Regional(ER) grid of India is one of the five regional grid consisting of voltage level 765kV, 400 kV, 220 kV and numerous buses at lower voltage range. Eastern Regional Grid is connected to North Eastern Regional Grid, Southern Grid, Northern Grid and Western Grid. Further, there are various HVDC lines or back to back systems which all together form the network of Eastern Grid. Depending on voltage level ER grid comprises of many bus. The system has been studied using 205 buses of voltage levels 220 kV and above and transmission lines running over a length of 23693 km. The paper studies the power flow simulation analysis of Eastern Grid of India with and without HVDC links using Power System Simulators for Engineering (PSS®E). Further, Simulations have also been performed for various kinds of faults as per IEC 60909 standard.

The goal of this work is to study the transient behavior of the cable against the application of standard and non-standard lightning impulse voltage waveforms. A 66 kV cable model has been developed in MATLAB Simulink and standard and non-standard impulse voltages are applied to it. A preliminary comparative study on the obtained voltages indicated that non-standard impulse voltage waveform developed higher voltage stress in the cable. Simulation results helped to investigate which impulses (standard or non-standard) represent the worst possible voltage stresses on the cables. This study provides the basis for further study of effects of non-standard impulse voltage waveforms and make necessary correction in the existing impulse testing standards.

The paper studies the load flow simulation studies of North Eastern Grid of India using PSS®E, well-accepted and commercial software from SIEMENS. The studied system comprises of 143 buses of different voltage levels and transmission lines running over a length of 6445 km. 80% loading for all the lines has been assumed for this study. The results have been validated by solving the model using DIgSILENT, also commercially known as Power Factory and a satisfactory convergence in both of the result has been seen. Simulations have also been performed for various kinds of faults.

The electromagnetic radiations from High Voltage Transmission lines are causing serious health threats to human beings working outdoors. Interference from HV lines may be electrostatic and electromagnetic interference. Probable risk for leukemia, neuropsychological disorders, cancer and reproductive outcomes has been reported due to this exposure. This paper is aimed at analysis of electric field distribution in a 400kV transmission line. Electric Field is calculated using FEM based ANSYS software package. By comparing these values with the standard available guidelines and the values calculated by analytical method we can find the permissible distance that the human beings may be exposed to.

Assessment of the dynamic characteristics of surge arrester is an important aspect of insulation coordination. Computer simulation of residual impulse voltage test of surge arrester models have been done using Alternative Transients Program (ATP) and Power systems computer aided design (PSCAD) design softwares. In this paper, the models have been developed in MATLAB Simulink. The accuracy of the models are ascertained by comparing the results with the manufacturer's design data.

Utilization of renewable energy resources have been the most important & prospective field to seek new energy sources to meet up the increasing demand in power all over the world specially in a developing country like India. Grid-connected photovoltaic systems are providing a viable technology for producing electrical energy by using renewable energy resources. High power density, high efficiency and reliability for this system are important design considerations along with control objectives like Maximum power point tracking (MPPT), grid synchronization, islanding detection and prevention, sinusoidal current injection into the grid, maintaining the THD within certain permissible limit (

In the case of multiple fringes and complex frequency measurements, the frequency of the output signal changes rapidly when the vibration changes and frequency breakdown takes place at the turning point. For a particular vibration signature containing many frequency components at different time intervals, it is often difficult to trace the direction of the vibration as well as individual frequency peaks. In such cases, advanced signal-processing scheme is necessary to decode the vibration signature. This paper investigates the data interrogation technique for multifrequency and complex signals of surface vibration obtained from an extrinsic Fabry-Pe/spl acute/rot interferometric sensor. In this paper, wavelet transform (WT)-based signal processing methodology has been employed to count of optical fringes with special reference to signals having subfringes. A WT-based tool has also been developed for unambiguous identification of frequency components from a nonsinusoidal vibration. The results of such WT-based analyses are presented, and merits as well as demerits of the proposed methods are discussed.

Vulnerability analysis in modern power systems is essential to mitigate cascading failures. This assumes prominence in the wake of permeation of information and communication technologies in the operation of power systems. Most research works have focused on vulnerability analysis of either general interdependent infrastructure systems or power systems. As a part of this work, it will be of interest to identify the existing approaches in vulnerability analysis in power systems as well as ICT infrastructures. Phaser Measurement Units (PMUs) are typically used in Wide Area Measurement (WAM) systems to predict and prevent cascading failures. The role of PMUs in preventing cascading failures because of interaction between ICT and the power grid in future Smart Grid is reviewed.

Interferometric optical fibre sensors have proved to be many orders of magnitude more sensitive than their electrical counterparts, but they suffer from limitations in signal demodulation caused by phase ambiguity and complex fringe counting when the output phase difference exceeds one fringe period and for multiple fringes. This paper presents a novel signal decoding technique based on the wavelet transform of optical data extracted from a non-contact vibration sensor using an extrinsic Fabry-Perot interferometer (EFPI) implemented using single-mode fibre. The EFPI cavity has been used to generate an optical interference signal between two parallel, highly reflective surfaces separated by a variable distance. Firstly, a few recorded experimental results of the interference fringe formation due to vibration are presented in this paper. Then the wavelet transform is used for decoding the vibration signature for three major purposes of the data analyses, namely elimination of noise from the optical signals collected in real time, identification of the frequency breakdown points of the signal efficiently and automatic counting of the interference fringes. In turn, the wavelet transform is successfully employed to decode the vibration signature from the non-stationary output signal of an EFPI sensor.

Bewley's lattice diagram is a graphical method that has been widely used for determining value of a travelling wave (TW) in transient analysis. The method provides a very simple representation for voltage and current surge reflections as it travels along the transmission system. From an extensive literature survey it was concluded that till date use of digital computers by developing a program for the same computation has not been done. This paper aims at an approach for the development of a program for this method using MATLAB. Coding has been done for few specific practical cases of transmission system. Results for all those cases have been presented in this paper. And finally with the achieved results a discussion has been done on the possible future work in this direction.

A switched reluctance motor is a variable speed motor in which switching of current results in the production of torque and power. Due to the doubly salient structure of switched reluctance motor high acoustic noises and vibrations are produced along with torque ripple. In order to overcome these hindrances bearing-less switched reluctance motor was introduced as a solution to this problem. The motoring action of a switched reluctance motor can be combined with a magnetic bearing action to get a single unit called self-bearing switched reluctance motor. It is an electromagnetic device that has the capability of supporting the rotor on its own, generating magnetic forces by the windings on its stator. This paper presents an extensive literature survey on self-bearing switched reluctance motor and its recent developments including its various purposes in industrial applications. Details of its working principle, design methodologies, winding designs, control strategies and some prototype developments have been studied and presented.

Efficient utilization of electrical energy plays a significant role for sustainable development of the industries. Moreover, effective implementation of energy efficiency technology in the industrial infrastructure and production chain is a part of smart grid mission. However, the cost effectiveness of the project is always a constraint for adoption and implementation. In this paper, for demand side management, an appropriate rule based strategy has been proposed which improves the energy efficiency of a production unit in a cost effective manner. Also, an attempt has been made to develop a fair trade-off based captive renewable power augmentation scheme which will further enhance the cost effectiveness of the presented energy efficiency model for the plant. Moreover, this approach can significantly reduce the maximum demand of the plant which will unburden the power utility. The developed model has been applied in a cement-asbestos industry considered for case-study which produces satisfactory results. The proposed model can be suitably customized for other type of production industries. The trade-off mechanism has been validated using HOMER Pro-3.2 software.

This paper aims to highlight the observations made on surge performance of a power transformer. The impulse test on power transformers simulates the conditions that exist in service when a transformer is subjected to an incoming high voltage surge due to lightning or other disturbances on the associated transmission line. A simulated non-linear transformer model helps to analyze the surge response under varying impulse waveforms accurately and so surge modeling of the transformer using MATLAB SIMULINK has been done. For a range of applied waves (both standard and non-standard) and different winding connections, comparison of the insulation characteristics under non-standard lightning impulse voltage waveforms which represent actual surge waveforms encountered in the field and the characteristics under the standard lightning impulse waveform quantitatively can be made. An investigation on the transformer behavior when subjected to standard and non standard impulse waves is done in this paper. The maximum voltage to ground and maximum voltage across the coils along with the time of their occurrences against different coils for 0% tapping and 10% tapping respectively is recorded and analyzed.

Busbars, being one of the most critical components of a switchyard where all the power system equipments are connected, needs an important attention from protection and from reliability point of view. Any maloperation may lead to threat for system stability but instant clearance is needed during a fault to avoid cascaded tripping. Many protection schemes have been devised starting from over-current protection to differential schemes using numerical to microprocessor based analysis in recent times. The paper reviews different aspects of busbar protection schemes and the recent trends of protection and their advantages including steps taken to overcome the problems of CT saturation and ratio mismatch of CT secondary.

This paper aims to validate the surge modelling of a transformer using Matlab-Simulink using an electromagnetic model and thereby ascertaining the model accuracy. The studies cover winding responses to both full and chopped standard lightning impulses with time to chop varying over a wide range. Modelling was carried out using the design data of a 3 MVA, 33/11 kV, 3-phase, 50 Hz, Dyn 11 Transformer whose 33 kV mesh connected winding was considered to be subjected to standard full wave (1.2/ 50 μs) and chopped impulses chopped at 3 μs, 8 μs and 15 μs. The mathematical model considered takes into account the series and shunt capacitances and inductances of the winding elements, including the effect of their mutual inductances. The Simulation compared with the experimental results shows the validity of the Surge modelling of the transformer. Keywords - Modelling, Lightning Surges, Transformer winding, Transients.I. INTRODUCTION n a power system a power transformer is the most important and expensive piece of equipment. The fundamental work on transients in a magnetic winding was done by Wagner [1] 1915. Great progress has been made since 1915 in understanding the physical phenomenon which govern the transient response in transformer. Required transformer insulation is determined to a great extent by the transient voltages and stresses which appear in the transformer winding. Varying impulse voltages with long wave shape and large magnitude may be due to switching fault, lightning surge or by commercial impulse voltage test in the laboratory [2]. To design the insulation it is necessary to know the voltage appearing across the insulation (as a function of time) and the strength of insulation against the particular voltage wave. The study of the behaviour of a transformer winding with one grounded end is done when stressed by standard impulse voltage wave (1.2/50 μs) and chopped impulse waves chopped at 3 μs, 8 μs and 15 μs [2]. II. MODEL PARAMETERS The Transformer winding is represented by a network with distributed parameters as shown in Fig. 1. C, K, L and M represent the capacitance to ground, series capacitance, self inductance and mutual inductance per unit winding length respectively. Magnetic losses have been ignored [2, 3, 4].

This paper presents the study of transients resulting from different circuit topology in high voltage line. The analysed data are obtained from experiments as well as simulated model based on Simulink in matlab environment. The experimental set up as well as the simulation parameters are discussed along with the viability of the simulation model. The data are analysed using continuous wavelet transform and conclusions have been drawn thereafter.