S. Rama Reddy

Voltage sag/swell compensation using Z-Source inverter based dynamic voltage restorer

This paper presents the modeling and simulation of a dynamic voltage restorer as a voltage sag/swell mitigation device in electrical power distribution networks. The dynamic voltage restorer, with its excellent dynamic capabilities, when installed between the supply and a critical load feeder, can compensate for voltage sags/swells, restoring line voltage to its nominal value within few milliseconds and hence avoiding any power disruption to the load. A new topology based on Z-source inverter is presented in order to enhance the voltage restoration property of dynamic voltage restorer. Z-source inverter would ensure a constant DC voltage across the DC-link during the process of voltage compensation. The modeling of Z-source based dynamic voltage restorer is carried out component wise and their performances are analyzed using MATLAB software. The simulation results shows that the control technique is very effective and yields excellent compensation for voltage sag/swell mitigation.

Design and simulation of a photovoltaic induction motor coupled water pumping system

Efficiency is the sense of energy saving is a main issue in photovoltaic pumping. The objective of this work is to design and simulate an efficient battery less pumping system powered from photovoltaic panels, comprising a new push-pull converter with Induction Motor. In a photovoltaic pump-storage system, solar energy is stored, when sunlight is available as potential energy in water reservoir and consumed according to the demand. There are advantages in avoiding the use of large banks of lead acid batteries, which are heavy and expensive and have one fifth lifetime of photovoltaic panel. The DC/DC converter used in this system is the push-pull converter. It is commonly a two-switch topology. The primary advantage of push-pull converter is their simplicity and ability to scale up to high power throughput. Hence a pumping system based on an Induction motor can be an attractive proposal to overcome the drawback with DC motor and ensure reliable, costless and maintenance-free operation. Through this approach the drawbacks during the DC motor usage are overcome and a high power throughput is obtained from the designed push pull converter as it delivers accurate output value with low power losses and less output ripple because the converter has its own filter. In this project, an efficient push-pull converter-inverter fed Induction motor is designed, modeled and simulated using MATLAB simulink. Voltage spikes generated are reduced by a simple filter circuit. Fast Fourier transforms are carried out for the currents and voltages of three phase inverter with 120° and 180° conduction modes and corresponding total harmonic distortions are calculated in simulink for the selection of suitable inverter mode. Common mode voltage is also measured to find the noise ratio. This common mode noise is reduced using a filter. Open loop and closed loop systems are simulated and the results are presented.

Voltage sag/swell compensation in an interline Dynamic Voltage Restorer

The Dynamic Voltage Restorer (DVR) provides an advanced and economical solution for both voltage sag and swell problems. The voltage-restoration process involves real-power injection into the distribution system. The Interline DVR (IDVR) proposed in this paper provides a way to compensate the voltage deviation caused in a feeder. The IDVR consists of several DVRs connected to different distribution feeders in the power system sharing a common energy storage. Here, one DVR in the IDVR system works in voltage-sag/swell compensation mode while the other DVR in the IDVR system operate in power-flow control mode. The single phase model of the IDVR system is illustrated which is operated by Multiple Pulse Width Modulation (PWM). Open-loop and closed-loop control schemes of load voltage for a simple system is modeled and simulated using MATLAB software. The simulation results are presented to demonstrate the effectiveness of the proposed IDVR system.

ZVS LCL push-pull DC-DC converter with closed loop controlled PI controller

A high performance ZVS LCL push-pull DC-DC converter under closed loop control is analyzed with PI controller. Soft switching acquired by the primary MOSFET switches under LCL combination reduces the switching stress. Single device voltage drop on the primary side and resonating capacitor acting as tuned filter in the load side justifies an efficient converter. Quick settling time of error in the output for PI controller justifies its superior performance over other controllers. Circuit model developed for open and closed loop circuits are analyzed and simulated. Simulation results help in verifying the validity of PI controller for the closed loop controlled system.

Detection of broken bars in three phase squirrel cage induction motor using finite element method

Finite element method is more precise than the winding function approach, as it is based on the actual geometry of the machine and the machine model can easily be modified in order to study the effect of faults on the machines performance. Accurate models of the machine under healthy and faulty conditions are developed. This paper presents simulations of broken bars detection in a three phase squirrel cage induction motor under no load, half load and full load conditions for two and eight broken bars. The analysis is done using MagNet.

Modeling and Simulation of Faulty Squirrel Cage Induction Motor Using Magnet

867 Abstract—Induction motors are widely used in industry as prime electro mechanical energy conversion devices. Consequently the condition monitoring and fault diagnosis of induction motors have received significant attention recently and become an integrated part of various maintenance strategies. This paper presents the modeling and simulation of fault diagnosis of 3-phase squirrel-cage induction motor using magnet. The cross section of the machine was modeled with finite elements, and the field distribution and magnetic performance were computed. The fault considered in this work is broken bar condition. Simulation is performed using magnet and the results are presented.

Digital simulation of an Interline Dynamic Voltage Restorer for Voltage compensation

The Dynamic Voltage Restorer (DVR) provides an advanced and economical solution for voltage sag/swell problems. The voltage-restoration process involves real-power injection into the distribution system. The Interline DVR (IDVR) proposed in this paper provides a way to compensate the voltage deviation caused in a feeder. The IDVR consists of several DVRs connected to different distribution feeders in the power system sharing common energy storage. Here, one DVR in the IDVR system works in voltage-sag/swell compensation mode while the other DVR in the IDVR system operate in power-flow control mode. The single phase model of the IDVR system is illustrated which is operated by Multiple Pulse Width Modulation (PWM). Open-loop for sag/swell and closed-loop control for voltage swell for a simple system is modeled and simulated using MATLAB software. The simulation results are presented to demonstrate the effectiveness of the proposed IDVR system.

Design and Simulation of Energy Efficient Fixed Frequency Pulse Controlled Power Converter for Induction Melting Application

This paper discusses the design and simulation of pulse width modulated based circuit for induction melting application. This high frequency inverter topology have the practical advantages of energy saving, clean environment, high output power due to low switching losses, less electromagnetic noise and low total harmonic distortion. This two stage power converter has single phase full bridge rectifier, DC filter, zero voltage switching pulse width modulation controlled high frequency inverter. In this work, the steady state operation and control strategy of pulse width modulated high frequency inverter is analyzed. In order to achieve energy efficiency switching losses are reduced by operating the inverter above resonance frequency. Input side supply harmonics is also reduced using EMI filter. The simulation of the designed high frequency power supply is carried out at a frequency of 20 kHz using MATLAB simulink tool. Simulation results proof the energy saving due to reduction in switching losses of the presented control strategy and reduction in harmonic distortion of the presented power supply for induction heating load.

Simulation of Soft Switched Pwm Zvs Full Bridge Converter

This paper deals with the analysis and simulation of soft switched PWM ZVS full bridge DC to DC converter. The 48V DC is efficiently reduced to 12V DC using a DC to DC converter. This converter has advantages like reduced switching losses, stresses and EMI. Input DC is converted into high frequency AC and it is stepped down to 12V level. Latter it is rectified using a full wave rectifier. The simulation results are compared with the analytical results.

Modeling and simulation of closed loop controlled interleaved boost converter system

This paper deals with design calculations and simulation studies of interleaved boost converter cascaded with photovoltaic inverter for residential applications. Interleaved boost converter is mainly used for non conventional energy sources. IBC has two boost converters connected in parallel to reduce the ripple. Low voltage is boosted to higher level using IBC. The open loop and closed loop systems are modeled and simulated. The output waveforms are presented.