ANALYSIS OF ELECTRONIC LOAD CONTROLLER FOR THREE PHASE SYNCHRONOUS GENERATOR

USING FUZZY LOGIC

Presented by: ANURAG YADAV

Guided by : Dr. S.N. Singh

Alternate Hydro Energy Centre

Indian Institute of Technology Roorkee

INTRODUCTION Energy is the basic requirement for economic development

Mainly Coal, Petroleum, Natural gas, nuclear etc. are used to be exploited as versatile and high quality energy products

Utilities in many developing countries are finding it difficult to establish and maintain remote rural area electrification and other needs

The cost of delivering power to such areas is becoming excessively large due to large investments in transmission lines and large transmission losses

For these reasons, many utilities are seriously considering local renewable energy resources as an alternative to meet the load demand

ADVANTAGES OF HYDROPOWER

Clean energy source

Renewable source as it doesn’t utilize any fuel

Environment friendly

Easily integrable with grid and other energy

sources and can easily meet peaking demands

Very high conversion efficiency

OBJECTIVES

To develop the model of ELC in MATLAB/Simulink

To simulate the model and analyze it for various operating conditions

Interpretation of the results obtained through simulation

SCHEME OF ELC

ALTERNATOR ELECTRONIC LOAD CONTROLLER

CONSUMER LOADS

BALLAST/DUMP LOAD

ADVANTAGES OF ELECTRONIC LOAD CONTROLLER

Reduces the cost of Small Hydro installation

Provides smooth control of Voltage and Frequency

Efficient than a conventional hydraulic governor as it is faster in response

No complications and maintenance is very less

Maintains constant load on the generator irrespective of consumer load variations

SYNCHRONOUS GENERATOR

It works on the principle of electromagnetic induction

It runs at synchronous speed which is fixed by the line frequency and no. of poles

It can both export or import reactive power depending upon the type of excitation

Stable in operation and control

They are of Salient-Pole type or Cylindrical rotor type

In hydropower plants, Salient Pole Synchronous Generators are employed

SYNCHRONOUS GENERATOR

Droop Characteristics of two different Alternators

LITERATURE REVIEWAUTHOR(s) TOPIC WORK AND RESULTS

Jan Portegijs[1] 2000

The Humming Bird ELC/Induction Generator

• The humming bird ELC for both single phase and three phase Induction generator is being developed.

• Thyristorized control has been used to control the dump power consumption with two ballast loads.

• Design considerations for building and troubleshooting an ELC were described.

• Design is quite simple but its major disadvantage is the electronic noise which is due to the phase angle control strategy employed.

Arun Kant [2]2002

Design and development of a controller for Single Phase Induction Generator

• A design for load controller for Single-phase Induction Generator is developed.• A circuit for sensing the reference and actual frequency has also been developed.• Hardware of ELC has been developed using IC 555 timer utilizing the solid state electronic

devices and circuits. • Under-voltage,Overvoltage,Over-speeding protections are also being incorporated in the

model.• The model provides quite smooth control of voltage and frequency

S.S. Murthy,et al. [3]2003

Field experience on a novel pico hydel system using SEIG and ELC

• The field experience is being done by exploiting locally available small hydro potential needing minimal civil works

• Water is made to flow in a channel and stored in a forebay tank whose discharge is regulated to have nearly constant head.

• Thyristor based, diode based, Mark-space ratio/PWM based ELC’s were developed and these are being compared for their voltage regulation.

• IGBT based ELC is being found to yield the best performance.

V. Aggarwal [4]2004

Techno-economic study of micro hydro-turbine governing systems

• Study is being carried out keeping in mind the economic aspects of the turbine governing system.

• It is being concluded that the cost of penstock of ELC based system is less as the flow is constant.

• Constant flow condition also eliminates the water pressure or surge pressure.• It also eliminates the use of regulating equipment like guide vanes which further

adds to cost reduction.

S.P. Singh [5]2004

Design and development of single phase ELC for micro hydro power plant

• Worked and designed an ELC for a single phase system.• Design consistes of an uncontrolled rectifier in series with chopper switch (IGBT)

which is given pulse signal by PWM controller to control the switching.• Voltage and frequency are thus controlled and regulated.

S. Singh[6]2006

Design, testing and sensitivity analysis of ELC

• ELC is designed using phase angle regulation scheme which can vary from 0 to п.• The ELC is being made for single phase system and back to back thyristors are being

used in its design as it can be operated in both directions.• Switching occurs at twice the frequency and thus generates harmonic distortion as

high as 35-40%.• The results show that design is succesful for single phase system and that too upto

7kW.

B. Singh[7]2006

Analysis and design of ELC for SEIG

• ELC is being designed for stand-alone operating mode.• Uncontrolled rectifier and chopper based ELC is being developed with resistive

dump load.• IGBT is being used as a chopper switch.• It is being concluded from transient and steady state waveforms that ELC is able to

maintain constant voltage and frequency. This type of ELC can handle large power as compared to single phase one.

S.S. Murthy, et al[8]2006

A Novel Digital Control Technique of Electronic Load Controller for SEIG Based Micro Hydel Power Generation

• The work presents both transient and steady-state analysis of ELC• The operation of ELC is controlled using digital controller.• The controller is being tested in both laboratory and field.• This design of ELC is found to be more effective, faster, reliable, compact and cost-

effective.

J.M Ramirez, et al[9]2007

An Electronic Load Controller for Self-Excited Induction Generator

• The proposed ELC is reliable, simple and injects fewer harmonics.• The proposed ELC is conformed by a per-phase chopper circuit in series with dump load• Each switch is a combination of a couple of IGBT in anti-parallel connection.• The commutation pulses are obtained by PWM technique.

D.K. Palwalia, et al[10] 2008

Voltage and Frequency regulation of single phase SEIG

• ELC is being developed for single phase two-winding squirrel cage induction motor working as SEIG.• The error is generated based on the voltage difference between the actual and the

reference.• The error signal is compared with internally generated triangular wave of PWM

generation scheme which generates the pulses for firing the IGBT through an opto-isolation and pulse driver circuit.

B. Singh, et al [11]2008

VSC with Star-Delta Transformer based Electronic Load Controller for a stand alone power generation

• The proposed scheme presents an asynchronous generator driven by a pico hydro turbine and controller is connected at a point of common coupling through interfacing transformers.

• A star-delta transformer is used to form a four wire topology. It provides path to zero-sequence component of load current.

• Transformer is of three winding type with turns ratio as 2:2:1.• ELC serves the purpose of harmonic elimination, load balancing and reactive power

compensation for voltage control.• The results show that three phase system is balanced and sinusoidal.

B. Singh, et al [12]2008

Power Quality improvement in Conventional ELC for isolated power generation

• The designed ELC scheme consists of a 24-pulse rectifier with 14 diodes and a chopper.• A polygon wound autotransformer is being employed with reduced kVA rating for 24

pulse rectifier for harmonic reduction and to meet the power quality requirements as prescribed by IEEE standard-519.

• ELC’s are being developed using two schemes viz. six pulse bridge type and 24 pulse bridge type.

• The performance of both designs are being compared and it is concluded that 24 pulse bridge type ELC yields better performance.

• Experimental validation of the design has also been done.

B. Singh, et al[13]2008

Zig-zag transformer based ELC for isolated Asynchronous generator

• In this scheme, the VSC(Voltage source converter) and a zig-zag transformer are connected in shunt with the stator terminals of the generator.

• The neutral terminal for the consumer loads is created using a zig-zag transformer.• Two legs of the VSC are connected to the two phases while third phase is connected at

the mid-point of the DC bus capacitors of the VSC.• The cost, complexity, of ELC is less as compared to other ELC’s for four wire topology.

H. Ludens[14] 2010

Electronic Load Controller for Micro-hydro system

• The ELC is being developed for a single phase system.• The power circuit consists of eight TRIACs• It also employs a power transformer consisting of two secondaries.• One of the secondary is utilized to feed the line frequency and the other one to power

the control circuitry of thyristor.• ELC based on this scheme gives satisfactory performance.

V. Rajagopal [15]2010

Electronic load controller for isolated asynchronous generator in pico hydropower generation

• The work proposes a digital signal processor based ELC for asynchronous generator.• The control circuitry consists of excitation capacitors, voltage source converter, dc link

capacitor, a chopper, star/delta transformer, consumer loads and an auxiliary load.• The system provides a viable and cost effective solution to achieve power quality

improvement, voltage and frequency control, harmonic suppression and load balancing for feeding non-linear loads.

Anurag Chauhan [16]2010

Transient analysis of self-excited induction generator

• The ELC is being simulated for transient conditions such as process of self-excitation, voltage build-up, faults, unbalanced excitation, switching of resistive and dynamic loads.

• SEIG can safely feed an induction motor rated upto 50% of its rating.• Three-phase fault, L-L fault and unbalanced excitation cause voltage collapse and de-

excitation.• The dynamic behaviour of SEIG with ELC is satisfactory in constant power applications.

Shalini Singh[17]2010

Design and testing of ELC for hydropower plant

• The ELC in this scheme is designed and fabricated using thyristors.• The input is taken from generator through step down transformer and using the control

circuit, the triggering pulses are fed through the pulse transformer for gating the thyristors.

• The ELC is tested and shows that it is capable to maintain almost constant voltage.

S.N. Mahato, et al[18]2010

Transient performance of a three-phase SEIG supplying single phase load with ELC

• The work presents an SEIG feeding a single phase inductive load.• The effect of cross-saturation has also been incorporated.• The developed model has been validated through experiment by sudden removal and

application of load so as to check the effectiveness of the model.

S. Gao, et al[19]2010

Design of a Microcontroller based ELC for SEIG supplying Single Phase Loads

The ELC has been designed using Microprocessor interface.The ELC is an intelligent sensor in this caseThe operation of the controller is fast and also smooth and reliable control is obtained.

B. Singh, et al [20]2011

Electronic Load Controller for a Parallel Operated Isolated Asynchronous Generator Feeding Various Loads

The ELC is developed for induction generator operating in stand-alone mode.The model is simulated for linear/non-linear, balanced/unbalanced loading conditions.The controller is PI based.

B. Singh, et al[21]2011

Neural-Network-Based Integrated Electronic Load Controller for Isolated Asynchronous Generators in Small Hydro Generation

The work proposes a neural-network based integrated ELC for isolated asynchronous generator feeding a three-phase four wire load.The scheme uses adaptive linear element to extract the fundamental component of load current to control the voltage and frequency.The IELC is realized using zigzag/three single-phase transformers and a six-leg insulated-gate bipolar-transistor-based current controlled voltage-source converter, a chopper switch, and an auxiliary load on its dc bus.The model was simulated and also validated and found to give satisfactory performane.The controller is also simple, easy to control and less sensitive to load perturbations.

V. Rajagopal[22] 2011

Improved ELC for offgrid Induction Generator in SHP generation

ELC is being implemented using a digital signal processor.The design also balances the system under unbalanced loading conditions and also eliminates the harmonics in the load.THD of load current and terminal voltage lies within 5% as prescribed by IEEE-519 standard.Performance is very good under non-linear and unbalanced loading conditions.

Anjali Garg, et al [23]2011

A Fuzzy Logic Based Electronic Load Controller for Self-excited Induction Generators

The proposed scheme presents a fuzzy logic based ELC for asynchronous generator.The load current is being compared with the reference current and based on the error signal the input goes into Fuzzy logic controller.The proposed ELC gives better performance as compared to conventional controllers due to the use of fuzzy logic scheme.

Dibyendu Das[24]2011

Steady-State analysis of Electronic Load Controller for Three Phase Alternator

• The ELC is being developed using PD, PI and PID controller techniques.• The performance of ELC based on the three techniques is being compared and the

effect of varying the proportional, derivative and integral gain constants is also discussed.

• It is being concluded that PID based controller gives better performance as compared to other two.

• The system is not state controllable but the output is controllable as desired.

Érika S. Melo, et al [25]2013

Electronic Load Controller of a Micro-Hydro generator for stand-alone operation

The proposed scheme presents an ELC for single phase permanent magnet synchronous generator operating in isolated mode.A switched binary-weighted ballast load is connected in parallel with the main load.Binary-weighted resistors consists of six resistors connected in series.Each switch is triggered in integer cycles and on/off combinations provide 64 options of equivalent resistances that vary linearly.Comparison is being done between actual and reference frequency.The controller employed here is of PI type.Better results can be obtained by connecting more resistors to the ballast load.

Peeyush Kala[26]2013

Steady-state analysis of Fuzzy logic based ELC for SEIG

• In this scheme, fuzzy logic based ELC is being developed for self-excited induction generator.

• The model is simulated in MATLAB/Simulink environment.• The error signal is fed to the fuzzy logic controller based on the comparison between

reference voltage and actual voltage.• The results show that a better and quick restoration of the system takes place with

Fuzzy logic based controller.

Yellaiah. Ponnam [27] 2013

ELC for SEIG using fuzzy logic controller

• The proposed scheme consists of a Fuzzy logic based controller for SEIG operating in isolated mode.

• The error signal is generated by the comparison between the actual voltage and the reference voltage.

• Fuzzy logic based ELC gives faster response and the peak overshoot is also reduced.

C.Kathirvel, et al [28]2013

Fuzzy logic based voltage and frequency of a self excited induction generator for micro hydro turbines for rural applications

• The ELC based SEIG has been designed in this work.• The design is being tested using simulation in MATLAB/Simulink.• It is concluded that STATCOM or any other reactive power supply device needs to be

integrated with fuzzy in order to keep the voltage perturbations within safe limits.

B. Nia Roodsari , et al [29]2014

The Distributed Electronic Load Controller: A New Concept for Voltage Regulation in Micro hydro Systems with Transfer of Excess Power to Households

• The work presents a concept of distributed ELC.• The power going as a waste or dump to ballast load is utilized in various household

usage nearby.• This scheme provides good regulation of voltage and frequency.• The results showed that distributed ELC has more reliable performance than a

conventional one.

M. Prabhu Raj, et al[30]2014

Fuzzy Logic Control Strategy for Stand-Alone Self-Excited Induction Generator for a Variable Speed Wind Turbine

• The work presents a control strategy for SEIG connected to wind turbine and operating in isolated mode.

• The strategy aims to extract the maximum energy from the turbine and simultaneously regulating the terminal voltage over a wide range of speed variations.

• The dynamic performance is achieved using three fuzzy logic controllers.

B. Nia Roodsari , et al [31]2014

A New Electronic Load Controller for the Self-excited Induction Generator to Decrease Stator Winding Stress

• In this technique, a part of the dump load is being connected vin parallel with the consumer load so that stress on the stator windings can be reduced.

• The duty cycle varies with the variations in main load, which requires constant connection and disconnection of the ballast load.

• In the proposed scheme the ballast load has been divided into two parts for the reasons explained above.

GAPS IDENTIFIED

Fuzzy logic based ELC can be developed for Synchronous Generator

State space models for the controllers may be developed

Analysis can be done for inductive dump load

The Fuzzy logic based ELC can be integrated with microcontroller so as to improve the design

The controller can also be developed using Artificial Neural Network, Neuro-Fuzzy technique

FUZZY LOGIC Fuzzy logic is a multi-valued logic that deals with approximate rather than fixed and

exact reasoning Fuzzy logic variables may have a value that ranges between 0 and 1 It gives the freedom to use linguistic variables where the degree of truth or falsehood is

determined by defining the membership functions It gives a convenient way to map an input space to an output space It consists of a fuzzy inference system, rule editor, membership function editor and

surface viewer Fuzzy logic is robust, can be easily modified, use multiple inputs and outputs, gives

faster response compared to other controller Fuzzy logic is utilized practically in various day to day applications like washing

machine control, temperature control, water level control etc.

Fuzzification Fuzzy Inference System

Defuzzification

Rule Base

Membership Functions

Crisp Values Crisp Values

DESIGN OF THE PROPOSED MODEL

SIMULINK MODEL

Circuit Diagram of Three Phase uncontrolled rectifier

Conduction Table for rectifier operation

Waveforms pertaining to Uncontrolled Rectifier

DESIGN PARAMETERS OF THE CONTROL CIRCUIT

RULE VIEWER AND SURFACE VIEWER AT A GLANCE

SIMULATION RESULTS

SUDDEN LOAD APPLICATION

FIXED INITIAL LOAD

RESULTS & DISCUSSION

There is a sudden drop in the voltage due to sudden application of such a large load

There is an abrupt rise in the stator currents up-to 1.75pu due to sudden application of such a large load. However, there is a slight departure of stator currents due to the use of uncontrolled rectifier.

The speed drops suddenly below 0.99pu as shown in Fig. 4.5. There is also a transient at 0.1 second in the power dumped which finally settles down to a steady-state value of 10kW.

Voltage rises initially beyond 1pu and in about 0.2 seconds it settles to 1pu.

Stator currents shoot up beyond 1pu initially but settle to 1pu in about 0.1 second

As the generator is loaded up to its rated capacity, there is an initial transient in the power dumped which reduces to zero after sometime

The speed contains lesser number of transients as compared with the case of sudden load application

CONCLUSION Small change in speed/frequency of the system has been observed but the variation is within the safe limits. The current and voltage waveforms are slightly distorted due to the use of uncontrolled rectifier

The frequency ,voltage and other parameters of the alternator are restored in a very short duration

Lesser transients and overshoots are there due to the fuzzy logic based controller design and the operating parameters get restored to their normal values in a very short duration

Fuzzy logic controller based on ANN technique thus proves to be a strong candidate for designing the electronic load controller as compared to other conventional controllers

With the help of fuzzy logic controller, it is possible to control the sophisticated systems without the inclusion of complex mathematical equations

FUTURE SCOPE

State space model can be developed for PI and PID based controllers

Controller design can be improved by using neuro-fuzzy or other artificial intelligence control tools

STATCOM can also be integrated with ELC for reduction in the harmonic content of the rectified voltage for better regulation

The design can be practically developed and validated for the results in the laboratory

Analysis can be done for inductive dump load

A comparative study can be done for the ELC design based on PI, PID, PD and artificial intelligence techniques

LIST OF PUBLICATIONS

“A Fuzzy Logic based Electronic Load Controller for Three Phase Alternator”, International Journal of Emerging Technology and Advanced Engineering, Vol. 5, Issue 3, pp 514-520, March 2015

“Steady-State Analysis of Electronic Load Controller for Three Phase Synchronous Generator”, 12th IEEE International Conference, INDICON, December 2015(Communicated)

REFERENCES[1] Portegijs, Jan , “The Humming bird Electronic Load Controller /Induction Generator Controller”, final version, 6 December 2000. [2] Kant, Arun, M.Tech dissertation Work On, “Controller for Single Phase Induction Generator”, AHEC, IIT Roorkee, 2002.

[3] Murthy S.S., et al, “Field experience on a novel Pico Hydel System using SEIG and ELC”, IEEE Conference, Vol.2, pp 842-847, 2003.

[4] Aggarwal V., M.Tech dissertation Work On, “Techno-economic study of micro-hydro turbine governing systems”, AHEC, IIT Roorkee, 2004.

[5] Singh, S.P., M.Tech dissertation Work On, “Design and Development of Single Phase ELC for Micro Hydro Power Plant ”, AHEC, IIT Roorkee, 2004.

[6] Singh, S., M.Tech dissertation Work On, “Design, testing and sensitivity analysis of ELC ”, AHEC, IIT Roorkee, 2006.

[7] Singh B., et al, “Analysis and design of ELC for SEIG”, IEEE Transactions on energy conversion, Vol.21, No.21, pp 285-293, March 2006.

[8] Singh B.,et al, “Neural-Network based integrated ELC for isolated asynchronous generator in small hydropower generation”, IEEE Transactions on Industrial Electronics, 2006.

  

[9] Ramirez J.M, et al, “An Electronic Load Controller for Self-Excited Induction Generator” , IEEE Transactions on energy conversion, Vol.22, No.2, pp 1-8, 2007.

[10] Palwalia D.K., et al, “Voltage and Frequency Regulation of single phase Self-Excited Induction Generator”, Department of Electrical Engineering, Conference Paper, Indian Institute of Technology Roorkee, 2008.

[11] Singh B., et al, “VSC with Star-Delta Transformer Based Electronic Load Controller for a stand alone power generation, Department of Electrical Engineering, Conference Paper, Indian Institute of Technology Roorkee, 2008.

[12] Singh B., et al, “Power Quality Improvement in Conventional ELC for isolated power generation”, IEEE Transactions on energy conversion, 23, pp 764-773, 2008.

[13] Singh B., et al, “Zig-zag Transformer based ELC for isolated asynchronous generator”, 2nd IEEE International Conference on Power and Energy 1-3, pp 431-436, Johor Baharu, Malaysia, 2008.

[14] H. Ludens, Electronic Load Controller for micro hydro systems, http: // ludens.cl/, 2010.

[15] Rajagopal V., et al, “Electronic Load Controller for isolated asynchronous generator in pico hydropower generation”, Conference paper, Department of Electrical Engineering, Indian Institute of Technology Roorkee, 2010.

[16] Chauhan A., M.Tech dissertation Work On, “Transient analysis of self-excited induction generator with electronic load controller supplying static and dynamic loads, AHEC, Indian Institute of Technology Roorkee, 2010.

[17] Singh Shalini, M.Tech dissertation Work On, “Design and Testing of ELC for hydropower plant, AHEC, Indian Institute of Technology Roorkee, 2010.

[18] Mahato S.N, et al, “Transient performance of a three phase SEIG supplying a single phase load with ELC”, IEEE Conference, ESARS, Oct. 2010.

[19] Gao Sarsing, et al, “Design of Microcontroller based ELC for SEIG supplying single phase loads”, Journal of Power Electronics, Vol. 10, No. 4, July 2010.

[20] Singh B., et al, “Electronic load controller for parallel operated isolated asynchronous generator feeding various loads”, Journal of Electromagnetic Analysis and Applications Vol. 3  No. 4, Article ID: 4625, 2011.

[21] Murthy S.S., et al, “A novel digital control technique for ELC for SEIG based micro hydel power generation, IEEE International Conference on Power Electronics, drives and energy systems, 2011.

[22] Rajagopal V., et al, “Improved ELC for off-grid Induction Generator”, IEEE India International Conference on Power Electronics, 2011.

[23] Garg Anjali, et al, “A fuzzy logic based ELC for self excited induction generator”, Journal of Alternate Energy Sources & Technologies, Vol.2, No.2, 2011.

[24] Das Dibyendu, M. Tech dissertation Work On, “ Steady-State analysis of Electronic Load Controller for Three Phase Alternator” , AHEC, Indian Institute of Technology Roorkee, 2011.

[25] Erika S. Melo, et al, “Electronic Load Controller of a micro-hydro generator for stand alone operation” , IEEE Power Electronics Conference, Brazil, 2013.

[26] Kala Peeyush, et al “Steady-State Analysis of fuzzy logic based ELC for SEIG”, International Journal of Advancements in Research & Technology, Volume 2, Issue4, 2013.

[27] Yellaiah. Ponnam, et al, “Electronic Load Controller for SEIG using Fuzzy Logic”, IOSR Journal of Electrical and Electronics Engineering, 2013.

[28] Kathirvel C., et al, “Fuzzy Logic based voltage and frequency of a SEIG for micro-hydro turbines for rural applications”, Journal of Theoretical and Applied Information Technology, 2013.

[29] B. Nia Roodsari, et al, “The Distributed Electronic Load Controller: A New Concept for Voltage Regulation in Microhydro Systems with Transfer of Excess Power to Households”, ISES Solar World Congress, Vol.57 pages: 1465-74 Elsevier, 2013.

[30] M. Prabhu Raj, et al, “Fuzzy Logic Control Strategy for Stand-Alone Self-Excited Induction Generator for a Variable Speed Wind Turbine”, International Journal of Innovative Research in Science, Engineering and Technology, 2014.

[31] B. Nia Roodsari, et al, “A New Electronic Load Controller for the Self-excited Induction Generator to Decrease Stator Winding Stress”, ISES Solar World Congress, Vol.57 pages: 1455-64 Elsevier, 2013.

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