ELECTRICAL ENGG. Volume:91 2011 MAR

1		A Solution to the Load Flow Problem with Induction Motor using Modified Genetic Algorithm	This paper presents a solution to the load flow problem with induction motor using Modified Genetic Algorithm (MGA). The classical constant power load model is usually employed for load flow analysis. Since, the actual loads of power systems mostly have nonlinear voltage characteristics. The nonlinear load model is included into load flow problem that is essential to get better and precise results of load flow analysis. In this paper, the nonlinear model of induction motor load is included into the conventional load flow problem. Modified genetic algorithm involves a set of improved operators like Elitism, tournament selection and two point crossover, in order to increase its convergence speed and improve the quality of solution.In MGA, the objective function is to minimize the voltage and power mismatches and also constraining the power loss to a minimum value. This will results a precise solution to the load flow problem. To establish the validly of this method, the algorithm is tested with standard Ward-Hale six-bus system and with nine-bus system and the results are compared with simple genetic algorithm. It shows that speed of convergence is high and finds the precise solution for the problem.
2		A SVS Control Strategy for Damping Torsional Oscillations due to SSR in a Series Compensated Power System	The paper presents a Static VAR system (SVS) control strategy for damping torsional oscillations due to subsynchronous resonance (SSR) in a series compensated power system. The proposed SVS control strategy utilizes the effectiveness of combined reactive power and voltage angle (CRPVA) SVS auxiliary control signals. Eigenvalue analysis has been carried out using a linearized model of the power system.A digital computer simulation study, using a nonlinear system model, has been carried out to illustrate the performance of the proposed SVS control strategy under large disturbance conditions. It is found that the torsional oscillations are effectively damped out and the transient performance of the series compensated power system is greatly improved. This corroborates the outcome of the eigenvalue analysis.
3		Design of an LC VCO for Low Phase Noise and Low Power Consumption	This paper reports design of a voltage controlled oscillator (VCO) with high oscillation frequency, low power consumption and low phase noise. The oscillator is a single stage circuit and it has a low phase noise due to reduce noise sources. The design is implemented in cadence environment with 0.18 µm UMC technology. To evaluate the performance parameters the VCO is simulated in a 0.18 µm UMC technology using specter RF simulator.In this design frequency range was varied from 2.86 GHz to 3.3 GHz. Also the phase noise of the VCO at oscillation frequency of 3.3 GHz is to 122.84 dBc/Hz @ 1 MHz offset frequency and –124.39@100 MHz offset frequency, with the power consumption of 10.71 mW and tuning range of 8.53 %. In addition the present results with earlier published work has been compared 1,2 and obtained improvements. Also layout is designed at supply voltage of 2V and simulated results have been verified.
4		Modelling and Simulation of Optical Fibre based Temperature Sensor for Monitoring Dry Type Transformers	Breakdown of transformers prove to be very expensive and inconvenient because it takes a lot of time for their replacement. During breakdown the industry also incurs heavy losses because of stoppage in production line. A system for monitoring the temperature of transformers is required. Existing sensors cannot be used for monitoring the temperature of transformers because they are sensitive to electrical signals and can cause sparking which can trigger fire since there is oil in transformers cooling coils.Optical fibres are electrically inert so this system will prove to be ideal for this application. Results of investigations carried out by simulating a configuration of optical fibre temperature sensor for transformers based on micro bending using MATLAB7.5 as a simulation tool to evaluate the effectiveness of this sensor have been communicated through this paper.
5		Shunt Active Power Filter with a Novel Hysteresis Current Controller	Since the rapid development of the semiconductor industry, power electronics devices have gained popularity in our daily used electrical household appliances. Although these power electronics devices have benefited the electrical and electronics industry, these devices are also the main source of harmonics in the power system. Recently, the harmonic suppression facilities based on power electronic technique have been developed. These active harmonic suppression facilities known as active power filter which can suppress the different order harmonic components of nonlinear loads simultaneously. In this paper, a three-phase shunt active power filter using synchronous reference frame (SRF) strategy with a novel hysteresis current control technique is presented.For each 60 duration of line cycle, the three-phase controlled bridge can be considered as dual buck, buck and boost or dual boost configuration depending on the grid voltage and injected current polarities. Only two switches are controlled at high frequency at any instant of time. A threephase diode bridge with R-L load has been considered as nonlinear loads. Harmonics currents have been extracted by using SRF strategy and is used as reference current signal. A switching algorithm for injection of harmonic current has been developed. Simplicity of control circuit, reduction in switching losses with excellent dynamic performance are the salient features of the proposed hysteresis switching strategy.
6		Switched Reluctance Motor Converters Simulation : A High Efficiency Low Cost Comparative Performance Evaluation	The emergence of new applications for switched reluctance drive has created a need for low cost, compact converter topologies. A number of attempts were made in recent times to develop novel power electronic converter structures for SRM drives, based on their utilisation. This paper reviews the performance of various converters and the demonstrated by simulation.The proposed topologies are simulated using MATLAB/ Simulink software package and result is obtained. The computer simulation result supports the proposed methods of performance analysis of the converter. The comparative performance is also predicted.
7		Wing Technique Approach for the Detection of Stator Winding Faults in Three-phase Induction Motors	This paper presents a novel approach to diagnose inter-turn insulation faults and open circuit fault in threephase induction motor operating at different loading conditions. This approach is based on loci of instantaneous symmetrical components and requires measurement of three input stator currents. In this methodology, the effect of unbalance supply conditions, constructional imbalance and measurement errors are also investigated.The proposed technique helps improve the reliability, efficiency, and safety of the motor system and industrial plant and also allows maintenance to be performed in a more efficient manner, since the course of action can be determined based on the type and severity of the fault.