Transient Fault Response of Grid Connected Wind Electric Generators

Vol. 6 No. 4

Year : 2013

Issue : Apr-Jun

Title : Transient Fault Response of Grid Connected Wind Electric Generators

Author Name : G. Vikram, B. Linga Reddy , P.V. Prasad

Synopsis :

In recent years, as demand is increasing continuously, the search for renewable energy sources is intensified. Wind energy is one of the latest renewable energy sources and this paper is intended at presenting the impact of wind generators on the transient response of a power system network. The analysis is carried out for different types of wind generators i.e., Squirrel Cage Induction Generator (SCIG), Doubly Fed Induction Generator (DFIG) for asymmetrical fault i.e. LLG fault on the system and the simulation is carried out on Matlab/Simulink software.

Natural Harmonic Elimination of Square-Wave Inverter for Induction Motor Drive

Vol. 6 No. 4

Year : 2013

Issue : Apr-Jun

Title : Natural Harmonic Elimination of Square-Wave Inverter for Induction Motor Drive

Author Name : Seshagiri Boppana, G. Durga Prasad , T. Suresh Kumar

Synopsis :

Normally, high power voltage source inverters are very common in industry and need to provide sinusoidal output to the load for proficient operation. Sinusoidal wave output can be obtained in inverters by adopting various modulation techniques, which increases the switching frequency of the inverter elements like IGBTs and Power MOSFETs, which are having limited power handling capabilities. In case of moderate to high power output from the inverter, SCRs or GTOs need to be used as inverter switching elements. These devices are having limited switching frequencies making the inverter operation impossible using the high frequency modulation techniques. This results in an output with rich harmonic content. The latest multilevel inverters can be used to overcome these problems. But the circuit is very complex and also requires isolated power supplies to feed the inverter. In the proposed project, a low frequency square wave inverter using SCRs is operated along with a series connected pulse width modulated inverter, in each phase designed. The 3-phase SCR inverter basically works as a voltage source inverter producing square wave output. The series compensator used in each phase produce only the desired harmonic voltages to make the net output voltage sinusoidal, with small PWM switching harmonics only. The series compensators are designed using the IGBTs, forming a bridge inverter configuration.

Fuzzy Direct Torque and Flux Control of Induction Motor Using Fuzzy Speed controller

Vol. 6 No. 4

Year : 2013

Issue : Apr-Jun

Title : Fuzzy Direct Torque and Flux Control of Induction Motor Using Fuzzy Speed controller

Author Name : Sudheer, Kodad SF , Sarvesh B

Synopsis :

Classical DTC has inherent disadvantages such as: problems during starting resulting from the null states, the compulsory requirement of torque and flux estimators, and high torque ripple. In this paper classical DTC, Fuzzy DTFC along with Fuzzy logic based speed controller are designed and their results are compared. Classical DTC is improved by means of Fuzzy logic using 180 fuzzy rule base which eliminates hysterisis controllers and shows improved performance compared to classical DTC. The Classical DTC with PI type speed regulator results in high Torque and Flux ripples due to nonlinearity. In Fuzzy Logic DTFC torque and flux linkage hysterisis loop controller are eliminated and the transient and steady state performance of drive is improved due to fuzzy PI speed regulator. The improved performance and effectiveness of proposed method Fuzzy DTFC with Fuzzy Speed controller is evaluated through digital simulation using Matlab-Simulink.

Reducing Torque Pulsation of Induction Motor using Matrix Converter

Vol. 6 No. 4

Year : 2013

Issue : Apr-Jun

Title : Reducing Torque Pulsation of Induction Motor using Matrix Converter

Author Name : Sittanuri Chaitanya, Hussain Shaik

Synopsis :

This paper presents a design of Matrix converter using space vector modulation which is connected to an Induction motor. When the Induction motor is driven by a matrix converter using space vector modulation the torque pulsation is reduced and improves the speed of the motor. Switching losses of the converter is also reduced. Matrix converter does not require any DC link. Matrix converter has its unique feature is pure sinusoidal. Because of this feature harmonic losses are reduced. Thus the matrix converter improves overall performance of the motor. Matrix converter is a better alternative for PWM inverters. The simulation performance on matrix converter connected an induction motor using Matlab/simulink show good response of speed and torque. The matrix converter is superior to inverter drives because of its regeneration ability and four-quadrant operation. Therefore it meets the stringent energy efficiency and power quality.

Condition Monitoring of SF6 Filled Make Switch with Special Emphasis on Troubleshooting

Vol. 6 No. 4

Year : 2013

Issue : Apr-Jun

Title : Condition Monitoring of SF6 Filled Make Switch with Special Emphasis on Troubleshooting

Author Name : G Venkateswarlu, N.R. Mondal , J.R. Gajbhiye

Synopsis :

Make switch is used in short circuit testing laboratories. The Make Switch used in CPRI laboratories combine high current (80 kA rms) or high voltage (up to 24 kV rms) of electrical circuits with a brief and accurate closing time (<14 ms, ± 0.2ms) during a 100msec to 3sec short circuit test. The role of make switch during short circuit testing is crucial. Hence condition monitoring of make switch should get utmost important in the short circuit plant. Make switch cannot open under load,and is designed to ensure desired operation and facilitate maintenance of of it. During operation of make switch, safety of equipments is of prime importance. It is to be ensured that any operation of make switch does not damage its own parts or other electrical equipments. This is achieved by proper designing of mechanical and electrical interlocks in the control scheme. This paper emphasizes the importance of make switch during short circuit testing and its condition monitoring & troubleshooting.

Application Of Differential Evolution Technique For Short Term Hydrothermal Scheduling And Its Comparision With Other Meta Heuristic Search Algorithms

Vol. 6 No. 3

Year: 2013

 
Issue: Jan-Mar

Title: Application Of Differential Evolution Technique For Short Term Hydrothermal Scheduling And Its Comparision With Other Meta Heuristic Search Algorithms  

Author Name: S.Padmini, C. Christober Asir Rajan

 

Synopsis:

This paper proposes an application of Differential Evolution Technique(DE) for solving short- term scheduling problem.Generally Short-term hydrothermal scheduling involves the hour by hour scheduling of all generation on a system to achieve minimum production cost.A set of starting conditions is given and the optimal hourly schedule that minimizes the desired objective,while meeting hydraulic and steam constraints is sought and solved using Differential Evolution. . The results are examined to validated the effectiveness of the algorithm in comparision with other Meta heuristic algorithms like GA, GS, IFEP, SA and PSO.

Design and Simulation of AC to DC Single Stage Converter for Low Voltage Application

Vol. 6 No. 3

Year: 2013

 
Issue: Jan-Mar

Title : Design and Simulation of AC to DC Single Stage Converter for Low Voltage Application 

  

Author Name : Honey Susan Eldo, Dhayalini. K

Synopsis :  

In this paper, an ac/dc converter is presented that can boost very low ac voltages to a higher dc voltage. The converter is based on a new hybrid form of boost converter and a buck boost converter and it is suitable for power harvesting applications too. The measured prototype can supply 3.3V by converting an input voltage of 400mV delivered by an electromagnetic microgenerator. Detailed analysis of converter is carried out and based on that control schemes are proposed to operate the converter.

Simulation and Performance of Matrix Converter with Faulty Conditions

Vol. 6 No. 3

Year: 2013

 
Issue: Jan-Mar

Title : Simulation and Performance of Matrix Converter with Faulty Conditions   

Author Name : Dr.S.Sankar, Dr.S.Saravanakumar , M.Padmarasan 

Synopsis : 

This paper presents a matrix converter for power flow management. The matrix converter has several advantages over traditional rectifier-inverter type power frequency converters. It provides sinusoidal input and output waveforms, with minimal higher order harmonics and no sub harmonics. The matrix converter having the ability to generate multilevel output voltages, this converter is able to produce better quality output waveforms than conventional matrix converter in terms of harmonic content. This paper gives the performance of a matrix converter and the qualitative analysis of some performance parameters is carried out. Some numerical results based on a simulation model of a matrix converter system are also presented. The simulations results of different load conditions are presented .The open loop controlled system is simulated and the waveform output is predicted at various conditions.

Investigation on Symmetrical Three Phase Hybrid Cascaded Multilevel Inverter With Reduced Number of Switches

Vol. 6 No. 3

Year: 2013

 
Issue: Jan-Mar

Title : Investigation on Symmetrical Three Phase Hybrid Cascaded Multilevel Inverter With Reduced Number of Switches

Author Name : V. Vidhya, C.R.Balamurugan , S.P.Natarajan

Synopsis :

This work proposes investigation on symmetrical three phase hybrid cascaded multilevel inverter topology with reduced number of switches and is able to create five level output. The main advantage of the proposed work is to reduce the number of switches when compared to the Cascaded Multi Level Inverter (CMLI). The reduced number of switches reduces the switching losses and improves the efficiency of the inverter. The variation of Total Harmonic Distortion (THD) in the inverter output voltage is observed for various modulation indices. Simulation is performed using MATLAB-SIMULINK. By comparing the various PWM techniques, such as COPWM-1, COPWM-2, COPWM-3 and COPWM-4, it is observed that Carrier Overlapping Pulse Width Modulation-3 (COPWM-3) provides output with relatively low distortion for all strategies and better DC bus utilization is obtained in (COPWM-1) and also comparing the various variable amplitude techniques, such as  VACOPWM-1, VACOPWM-2, VACOPWM-3 and VACOPWM-4, it is observed that Variable Amplitude Carrier Overlapping Pulse Width Modulation-3 (VACOPWM-3) provides output with relatively low distortion for all strategies and better DC bus utilization. Finally comparing the various PWM techniques with  the various variable amplitude techniques, It is observed that Variable Amplitude Carrier Overlapping Pulse Width Modulation-3 (VACOPWM-3) provides output with relatively low distortion for all strategies and better DC bus utilization is obtained in (VACOPWM-2).

Analysis of Temperature Field in Switched Reluctance Machine Based on Regression Technique

Vol. 6 No. 3

Year: 2013

 
Issue: Jan-Mar

Title : Analysis of Temperature Field in Switched Reluctance Machine Based on Regression Technique

Author Name : Annie elisabeth jebaseeli, S.Paramasivam

Synopsis : 

This paper presents   a novel method  for the  determination of   temperature rise in rotating electrical machine. Rise in the winding temperature was determined from the  estimated values of winding resistance during the heat run test conducted as per IEC standard. The estimation of hot resistance was modeled  using multiple variable linear regression . The modeled hot resistance helps to find the load losses at any load situation without using complicated measurement set –up. This technique was applied for the hot resistance estimation for Switched Reluctance Machine using the input variables as cold resistance, ambient temperature and temperature rise. The results are compared and they show a good agreement between measured and the computed values. The proposed method was verified using experimental results obtained from temperature rise test on a 2 H.P 8/6 Switched Reluctance Machine.