Informatics Publishing Limited

Vani Vijay ¹, C. Viswanatha ², P. Giridhar Kini ³

Affiliations
1 Senior Research Fellow, Energy Efficiency and Renewable Enenrgy Division, Central Power Research Institute, Bangalore- 560080, IN
2 EEE Department, Manipal Institute of Technology, Manipal - 576104, IN
3 Diagnostics Cables and Capacitors Division, Central Power Research Institute, Bangalore - 560080, IN

Abstract

Using load emulation, the performance of source side converters can be easily evaluated and improved without the need for actual load. Due to the increase in use of power electronic converters and SMPS based systems, the harmonic levels in load side has increased considerably. Hence emulation of variable THD load is very important in analysing the performance of source side converters and ensure the performance efficiency and power quality under such loads. Here a novel method of obtaining variable load using PWM control explained. The PWM is controlled in a rainbow sinusoidal fashion to obtain clipped waveform across a resistor so that harmonics is introduced in the Load. The power factor can also be varied in the system by paralleling it with leading and lagging converter circuits. The working principle, modelling and simulation are presented along with the results. Proposed technique provides accurate modulation of load THD and effect of harmonics loads on sources converter are also analysed using this.

Keywords

Load Emulation, harmonic loads, current clipping

Full Text

     

Vani Vijay ¹, P. Giridhar Kini ², R. Sudhir Kumar ¹

Affiliations
1 Energy Efficiency and Renewable Enenrgy Division, Central Power Research Institute, Bangalore- 560080, IN
2 EEE department, Manipal Institute of Technology, Manipal -576104, IN

Abstract

Pulse Width Modulation (PWM) control of MOSFET based converters is used in almost all electrical application for accurate and efficient operation, like in motor drives, power supply units, power conditioners etc. The algorithm of PWM control in such system is the most important factor determining the operational features which can be implemented using microprocessors, micro controller, digital signal processors or higher end technologies. Here a detailed study of micro controller programming is done for PWM control of MOSFET based converters. The method of configuring the controller for PWM generation and programming steps are explained in detail with an example of PIC16F877A micro controller. Hardware implementation is done and program variation for different operating characteristics are observed. Micro controller programming is easiest, accurate and cost effective method for PWM control of converter. The program is flexible and higher end micro controllers can be used for complex control technique.

Keywords

Programming, micro controller, PWM control

Full Text

     

Vani Vijay ¹, C. Viswanatha ², P. Giridhar Kini ³, R. Sudhir Kumar ⁴

Affiliations
1 Senior Research Fellow, Energy Efficiency and Renewable Enenrgy Division, Central Power Research Institute, Bangalore - 560080, IN
2 Electrical and Electronics Engineering department, Manipal Institute of Technology, Manipal - 576104, IN
3 Diagnostics Cables and capacitors Division, Central Power Research Institute, Bangalore - 560080, IN
4 Energy Efficiency and Renewable Energy Division, Central Power Research Institute, Bangalore - 560080, IN

Abstract

Solar Photo Voltaic (SPV) sources are widely used in present scenario of energy crisis for various applications including grid connected PV plants and grid isolated standalone applications. The performance of solar PV system is highly dependent upon the operating conditions of source and loads especially in standalone applications. The effect on various types of loads on standalone system can be easily analyzed at design stage and testing stage by using load emulation technique, where a virtual load is used to replace actual load, giving more flexibility and accuracy to loading conditions. Here a novel load emulator model is presented which can provide accurate variation in load power factor and THD compared to existing models. The converter decouples the current in to in phase and out of phase components and the in phase component can be regenerated. The model is simulated using MATLABTM simulation and the results are validated by comparing with experimental results obtained by loading SPV inverter with actual load. Hence the proposed load emulator is very useful in design and development of application specific solar PV systems and also for performance analysis of such systems based on various standards.

Keywords

Solar PV inverters, non-linear loads, low pf loads

Full Text

     

Vani Vijay ¹, Sudhir Kumar R. ¹, Pradeep K. ¹

Affiliations
1 Energy Efficiency and Renewable Enenrgy Division, Central Power Research Institute, Bangalore - 560080, IN

Abstract

Electrical equipment designed for a particular environmental condition may not provide satisfactory performance under other conditions of temperature and humidity. Specifically in the case of solar PV inverters, the efficiency and other system characteristics may vary as per the extreme climatic conditions at the place of installation. Here a comparative study of solar PV inverter performance under such extreme conditions is presented in terms of system efficiency and insulation resistance. The conditions as per relevant international standards are simulated in a climatic chamber and five samples are studied for the effect of extreme temperature and humidity conditions. It is found that the insulation resistance of few samples is varying drastically which will affect the system safety. Similarly the efficiency of the system is also affected. Similarly there is considerable change in the system efficiency also.

Keywords

Solar PV Inverters, Climatic Conditions, Insulation Resistance

Full Text

     

Aparna Paulose ¹, Vani Vijay ², Reeba S. V. ³, Neha Adhikari ²

Affiliations
1 Department of E&E, PES Institute of Technology, Bengaluru - 560100, IN
2 Energy Efficiency and Renewable Enenrgy Division, Central Power Research Institute, Bengaluru - 560080, IN
3 Department of Electrical Engineering, College of Engineering Trivandrum, Kerala - 695016, IN

Abstract

Solar PV based Power generation is gaining importance in the present scenario of energy crisis. Precise control of Solar PV inverter is a very important factor deciding the efficiency and performance of Solar PV sources. Space Vector Modulation (SVM) technique is widely used for pulse width modulation in inverters, especially for power supplies for obtaining improved sine wave output. It is based on the representation of the three phase quantities as vectors in a two-dimensional using α and β co-ordinates. Here, a new three–dimensional (3-D) space vector algorithm in a-b-c co-ordinates for multilevel inverters is presented, which is based on the 3-Dimensional geometry of the vectors. This method calculates the on-state duration of switching vector without involving trigonometric functions, look-up tables or coordinate system transformation. Hence the computational complexity is very less compared to other algorithms. The proposed scheme is explained for a multilevel inverter and simulation results are presented with comparison of performance of a two level inverter and a three level inverter using this technique. The results shows that the algorithm can be applied for higher level inverter so that it operates at reduced Total Harmonic distortion.

Keywords

Multilevel Inverters, Space Vector Modulation (SVM), Three-dimensional (3-D) Space Vector

Full Text

     

Vani Vijay ¹, S. V. Reeba ², R. Sudhir Kumar ³

Affiliations
1 Energy Efficiency and Renewable Energy Division, Central Power Research Institute, Bangalore - 560080, IN
2 Department of Electrical Engineering, College of Engineering Trivandrum, Kerala - 695016, IN
3 Energy Efficiency and Renewable Energy Division, Central Power Research Institute, Bangalore -560 080, IN

Abstract

Solar Photovoltaic (SPV) is the most important renewable energy source which is gaining importance in all fields of electrical utility. Utilization of SPV source in electrical drives applications can bring about a considerable change in the present day energy crisis. Here an SPV based Switched Reluctance motor (SRM) drive is presented which can be utilized in low power high speed and medium speed applications. SRMs have inherent advantages of low inertia, low rotor losses, robustness and simple construction. The operation of the converter circuit is with respect to the reluctance variation of the rotating machine which makes it different from other drives. Here a converter circuit is designed for the operation of SRM from SPV source. The SPV characteristics are different from a constant DC source since the output power and voltage varies with insolation and temperature. The proposed system is verified using LabVIEW^TM Simulation and the results are discussed.

Keywords

Solar Photovoltaic (SPV), Switched reluctance Motor (SRM), LabVIEWTM, Reluctance

Full Text

     

J. L. Nandagopal ¹, Lekshmi R. Chandran ², R. Remya ³, Vani Vijay ⁴

Affiliations
1 Asst .Prof, ,Dept. of Electrical & Electronics,Amrita Vishwa Vidyapeetham, Amritapuri Campus, Kollam-690525, IN
2 Asst. Prof, ,Dept. of Electrical & Electronics ,Amrita Vishwa Vidyapeetham, Amritapuri Campus, Kollam-690525, IN
3 M.Tech Scholar, Dept. of Electrical & Electronics ,Amrita Vishwa Vidyapeetham, Amritapuri Campus, Kollam-690525, IN
4 Energy Efficiency and Renewable Energy Division, Central Power Research Institute, Bangalore -560080, IN

Abstract

AC-DC converters are used in most of the electrical utility applications especially in battery charging. Here, a novel topology for single-stage bridgeless ac-dc converter is presented which can give an isolated output voltage and input power factor correction. The input current to an ac-dc converter is rich in low order harmonics and so the total harmonic distortion is high and input power factor is poor. Hence Power Factor Correction (PFC) schemes have been implemented. The effectiveness of the converter is tested and verified in PSIM^TM simulation software and in experimental hardware prototype. This topology is found to have reduced losses and better power factor correction compared to the single-stage PFC ac to dc converters with full-bridge diode rectifier. This topology is suitable for battery charging application with reduced losses and better power quality.

Keywords

AC-DC Converter, half-bridge, single-stage, power factor correction

Full Text

     

Vani Vijay ¹, P. Giridhar Kini ², C. Viswanatha ³, K. Pradeep ⁴

Affiliations
1 Energy Efficiency and Renewable Enenrgy Division, Central Power Research Institute, Bangalore- 560080, IN
2 E&E Department, Manipal Institute of Technology, Manipal - 576104, IN
3 Diagnostics Cables and capacitors Division, Central Power Research Institute, Bangalore - 560080, IN
4 Energy Efficiency and Renewable Energy Division, Central Power Research Institute, Bangalore - 560080, IN

Abstract

Efficiency of power electronics devices are highly dependent on temperature. Hence temperature compensation and heat sink design are very important factors in maintaining the performance quality of power electronic converters. Thus the ambient temperature at which the device is operating also effects the performance since the heat removal by heat sinks or cooling fans is affected by the ambient temperature. Here a detailed analysis of the dependency of losses in power electronic switches on the junction temperature and in turn ambient temperature is presented. A theoretical Analysis of conduction losses and effect of ambient temperature on it is presented along with a set of experimental results by analyzing the performance of a 850W Solar PV inverter at various ambient temperatures. The results are satisfactorily explaining the effect of ambient temperature on converter efficiency.

Keywords

Solar PV inverters, conduction Losses, heat sink, ambient temperature

Full Text

     

Vani Vijay ¹, P. Giridhar Kini ², C. Viswanatha ³, S. Jothi Basu ⁴

Affiliations
1 Energy Efficiency and Renewable Enenrgy Division, Central Power Research Institute, Bangalore - 560080, IN
2 E&E Department, Manipal Institute of Technology, Manipal - 576104, IN
3 Diagnostics Cables and capacitors Division, Central Power Research Institute, Bangalore - 560080, IN
4 Energy Efficiency and Renewable Energy Division, Central Power Research Institute, Bangalore - 560080, IN

Abstract

AC-DC converters are very commonly used in many power electronics applications including controllable sources and machine drives. Rectifier circuit results in harmonic distortions in AC side and requires large capacitive filter for reducing DC ripples on the output side. Use of active power factor technique can be utilized for solving this issue resulting in better performance of the converter. It basically consists of boost converter with high frequency switching following the rectifier controlled using a suitable microcontroller. This paper presents the detailed design and operation of Active power factor corrected rectifier which operates with reduced THD and improved power factor there by reducing losses in power flow and utility. Simulation of the designed converter and comparison with conventional topology is also discussed.

Keywords

Rectifier; active power factor correction, capacitive filtering

Full Text

     

Vani Vijay ¹, P. Giridhar Kini ², C. Viswanatha ³, S. Jothi Basu ⁴

Affiliations
1 Energy Efficiency and Renewable Enenrgy Division, Central Power Research Institute, Bangalore-560080, IN
2 E & E Department, Manipal Institute of Technology, Manipal-576104, IN
3 Diagnostics Cables and capacitors Division, Central Power Research Institute, Bangalore-560080, IN
4 Energy Efficiency and Renewable Energy Division, Central Power Research Institute, Bangalore-560080, IN

Abstract

Inverter and power conditioning circuit is the most important part of solar PV system which is responsible for providing the AC output as per the requirement of the application. The presence of AC harmonics and DC ripples in the inverter is still an unavoidable drawback, even though it has reduced to a great extent in past two decades. This paper presents a detailed study of distortions in the AC and DC sides of commercial standalone single phase Solar PV inverter and the effect of the same in the application. The harmonic content is evaluated by loading the inverter using electronic loading. The reduction in distortions in the AC and DC sides by utilization of a high impedance network on the DC side of the inverter is also evaluated by simulation. A comparative study of harmonics and DC ripples in the inverter under test and the simulated impedance source inverter is also presented.

Keywords

Harmonics, Stand alone Solar PV inverters, DC ripples, Impedance network

Full Text

     

Vani Vijay ¹, Giridhar Kini P. ², Viswanatha C. ³, Jothibasu S. ⁴

Affiliations
1 Energy Efficiency and Renewable Enenrgy Division, Central Power Research Institute, Bangalore- 560080, IN
2 E&E department, Manipal Institute of Technology, Manipal 576104, IN
3 Diagnostics Cables and capacitors Division, Central Power Research Institute, Bangalore-560080, IN
4 Energy Efficiency and Renewable Energy Division, Central Power Research Institute, Bangalore -560080, IN

Abstract

Back to Back converters are commonly used converters in many ac to ac conversion applications. Even though Converters without intermediate energy storage element are developed, Those with DC link capacitors still continue to be most popular due to the inherent advantages. The performance of such converters is affected by the operation of DC link capacitors used. This paper gives a detailed study of various types of back to back converters and considerations in DC link capacitor design and selection. A MATLAB program is also developed to analyze the effect of RMS (Root mean Square) ripple current and consequent effect on the life of the DC link capacitors in Voltage link back to back converters.

Keywords

Back to back converters; matrix converter, DC link capacitors.

Full Text

     

Vani Vijay ¹, Kini P. Giridhar ², C. Viswanatha ³, S. Jothi Basu ⁴

Affiliations
1 Energy Efficiency and Renewable Enenrgy Division, Central Power Research Institute, Bangalore- 560080, IN
2 E&E department, Manipal Institute of Technology, Manipal 576104, IN
3 Diagnostics Cables and capacitors Division, Central Power Research Institute, Bangalore 560080, IN
4 Energy Efficiency and Renewable Energy Division, Central Power Research Institute, Bangalore -560080, IN

Abstract

Back to back converters are used in many applications including machine drives and HVDC links. It is a combination of AC to DC and DC to AC converters with topologies suitable for the application. Here a single phase converter topology is developed by combining a Z source network and HERIC inverter which operates with lesser losses and more controllability. Compared to conventional inverter model, the conduction losses are much less in HERIC configuration. The Z source network help in boosting the DC voltage level so as to obtain the required level of AC output. This back to back converter is mainly meant for regenerative load application which can be utilized in equipment testing. The power drawn by the converter can be regenerated to supply back to the utility grid there by it is possible to conduct equipment testing without wasting energy. The details of the proposed configuration and the output wav forms are explained. Also a comparative study of the losses in conventional converter and proposed converter is presented.

Keywords

Back to back converter, HERIC inverter, Z source nettwork, regenerative load

Full Text

     

Vani Vijay ¹, Giridhar P. Kini ², C. Viswanatha ³, S. Jothi Basu ⁴

Affiliations
1 Energy Efficiency and Renewable Enenrgy Division, Central Power Research Institute, Bangalore- 560 080, IN
2 E&E department, Manipal Institute of Technology, Manipal 576104, IN
3 Diagnostics Cables and capacitors Division, Central Power Research Institute, Bangalore 560 080, IN
4 Energy Efficiency and Renewable Enenrgy Division, Central Power Research Institute, Bangalore -560 080, IN

Abstract

All newly designed power electronic equipments are to be tested as per the standards, so as to verify the response of the equipment under various load conditions. For this, different linear, non-linear and dynamic loads are to be applied to the equipment in accordance with the applications. Load emulation is the process by which the actual load is replaced by a flexible system which can mimic the characteristics of the actual load. A regenerative operation can be implemented in power electronic emulators. Thus by using load emulators for testing, the energy lost in testing of equipments can be reduced to a great extent. Here a review of various types of load emulators is presented which are intended for various types of applications along with some experimental results obtained in various research studies.

Keywords

Load Emulation, Non-linearity, Power Regeneration, Phase Locked Loop

Full Text