Simulation and Analysis of Stand-alone Photovoltaic System with Boost Converter using MATLAB/Simulink

ABSTRACT:  

Use of renewable energy and in particular solar energy has brought significant attention over the past decades.  Many research works are carried out to analyze and validate the performance of P V modules. Implementation of experimental set up for P V based power system with DC-DC converter to validate the performance of the system is not always possible due to practical constraints. Software based simulation model helps to analyze the performance of P V and a common circuit based model which could be used for validating any commercial P V module will be more helpful.

Simulation

of mathematical model for Photo voltaic (P V) module and DC-DC boost converter is presented in this paper. The model presented in this paper can be used as a generalized P V module to analyze the performance of any commercially available P V modules. I-V characteristics and P-V characteristics of P V module under different temperature and irradiation level can be obtained using the model. The design of DC-DC boost converter is also discussed in detail. Simulation of DC-DC converter is performed and the constant DC supply fed converter and P V fed converter generates the results.

 BLOCK DIAGRAM:

Fig. 1 Sim u link Model of proposed system

EXPECTED SIMULATION RESULTS:

Fig.2 P WM Pulse generation

Fig. 3(a) Input Voltage of DC-DC Boost Converter

Fig. 4(b) Output Voltage of Boost Converter constant DC input supply

Fig. 5 (c) Output current of Boost Converter constant DC input supply

Fig. 6 (a) Input voltage of P V fed converter

Fig. 7 (b) Output voltage and current waveform of P V fed converter

Fig. 8. Change in irradiation level of P V Module

Fig. 9. Output Voltage and Current wave forms of Boost Converter at

different irradiation level.

CONCLUSION:

A circuit based system model of P V modules helps to analyze the performance of commercial P V modules. The commonly used blocks in the form of masked subsystem block develops a general model of P V module. I-V and P-V characteristics outputs are generated for MS X 60 P V module under different irradiation and different temperature levels and the matlab/simulink simulates the module under various conditions as presented in the data sheet. The results obtained from the simulation shows excellent matching with the characteristics graphs provided in the data sheet of the selected models.

Thus,

the model can be used to analyze the performance of any commercial P V module. Matlab/Simulink simulates the DC-DC boost converter and the converter generates  the results with constant DC input supply and by interconnecting the P V module with it. The results shows close match between the output of converter with constant DC input and the P V fed converter. The P V fed DC-DC boost converter generates the output voltage and current for change of irradiation levels at constant temperature is also presented.

REFERENCES:

 [1] J. A. Go w, C.D.Manning, “ Development of photo voltaic array model for the use in power electronic simulation studies,” I E E Proceedings Electric power applications, Vol. 146, No.2, March,1999.

[2] J e e-H o o n Jung, and S. Ahmed, “Model Construction of Single Crystalline Photo voltaic Panels for Real-time Simulation,” IEEE Energy Conversion Congress & Expo, September 12-16, 2010, Atlanta, USA.

[3] T. F. E l shatter, M. T. E l ha g r y, E. M. Ab o u-E l z a  h a b, and A. A. T. Elk o u s y, “Fuzzy modeling of photo voltaic panel equivalent circuit,” in Proc. Conf. Record 28th IEEE Photo voltaic Spec. Conf., pp. 1656– 1659, 2000.

[4] M. Ba l z a n i and A. Re at ti, “Neural network based model of a P V array for the optimum performance of P V system,” in Proc. P h.D. Res. Micro electron. Electron., vol. 2, pp. 123–126, 2005.

Solar Photovoltaic Powered Sailing Boat Using Buck Converter

ABSTRACT

 The main objective of this paper is to establish technical and economical aspects of the application of stand-alone photovoltaic (PV) system in sailing boat using a buck converter in order to enhance the power generation and also to minimize the cost. Performance and control of dc-dc converter, suitable for photovoltaic (PV) applications, is presented here. A buck converter is employed here which extracts complete power from the PV source and feeds into the dc load. The power, which is fed into the load, is sufficient to drive a boat. With the help of matlab simulink software PV module and buck model has been designed and simulated and also compared with theoretical predictions.

KEYWORDS

  1. Buck Converter
  2. Ideal Switch
  3. Matlab Simulink
  4. PV
  5. Solar Sailing Boat

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM

Figure 1. Schematic Diagram of PV powered Sailing Boat

 EXPECTED SIMULATION RESULTS

 Figure 2. Simulation result of maximum voltage, current and power in PV array

Figure 3. Simulation result of Buck converter

Figure 4. Simulation result of PV with Buck

 CONCLUSION

Here proposed a solar PV powered sailing boat using buck converter. And tested the effectiveness of the proposed control scheme. This is a new and innovative application which is fully environmental friendly and is almost pollution less. As the upper portion of the boat is unused, solar panels are implemented in that portion quite easily, without requiring extra space. Fuel cost is not required in day time due to the presence of sunlight. lastly, energy pay back period will be lesser than diesel run boat.

 REFERENCES

 [1] P V or  ob i e  v, Y u. V or ob i  e v. Automatic Sun Tracking Solar Electric Systems for Applications on Transport. 7th International Conference on Electrical Engineering, Computing Science and Automatic Control. 2010.

[2] Nob u  y u l  u K  as a, Ta  k  ah i k o Ii d a, Hide o I w a motto. An invert er using buck-boost type chopper circuits for popular small-scale photo voltaic power system. IEEE. 1999.

[3] Pen g Zhang, Wen yuan Li, S her win Li, Yang Wang, Wei dong Xi a o. Reliability assessment of photo voltaic power systems: Review of current status and future perspectives. Applied Energy. 2013; 104(2013): 822–833,

[4] M Nag a o, H Ho r i k a w a, K Ha r a d a. Photo voltaic System using Buck-Boost PW  M Invert er. Trans. of IE E J. 1994; ll 4(D): 885-892.

[5] A Z e g a o u i, M Ail l e r i e, P Pet it, JP S a wick i, JP Charles, AW Be la r bi. Dynamic behavior of P V generator trackers under irradiation and temperature changes. Solar Energy. 2011; 85(2011): 2953–2964.

Space Vector Pulse Width Modulation Fed Direct Torque Control Of Induction Motor Drive Using Matlab-Simulink

ABSTRACT:

Now a day’s induction motor drives are highly demanding to design both mechanical and electrical drive system which is used widely in many industrial applications. Recent years many mathematical models for induction motor drive using Simulink models are employed. Scalar and Vector control method can be applied to induction motors in three phases symmetric as well as unsymmetrical two-phase form. The mathematical and Simulink operation of the induction motor drive can be studied and it is equivalent to a DC motor by the vector control method. With the combined performance of the numerical electronics and power electronics we are capable to smoothly control the variable speed and torque in low power industrial operations. With the help of technological achievements, several command and control techniques are developed by the technologists to control the time, flux and torque of the industrial electrical machine drives. The direct torque control (DTC) technique is one of the most advanced mechanisms in control operation of torque and speed. This technique with SVPWM gives fine regulation without rotational speed controlled feedback. The electromagnetic torque and stator flux are estimated in DTC technique only stator currents and voltage and it is independent of the parameters of the motor except for the Rs i.e. stator resistance [7].

KEYWORDS:

  1. Controller
  2. DTC
  3. IDM
  4. SVPWM and switching table.

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 

 Fig.1. DTC block diagram

EXPECTED SIMULATION RESULTS:

 

Fig.2. Electromagnetic torque

Fig.3. Rotor speed

Fig.4. Stator current

Fig.5. d-axis stator flux

Fig.6. q-axis stator flux

Fig.7. Electromagnetic torque

Fig.8. Rotor speed

Fig.9. Trajectory of direct axis stator and quadrature axis

flux (stationary reference frame)

Fig.10. Electromagnetic torque

Fig.11. Rotor speed

Fig.12. Direct axis stator flux

Fig.13. Quadrature axis stator flux

Fig.14. Direct axis stator current

Fig.15. Quadrature axis stator current

Fig.16. Stator flux trajectory

Fig.17. Rotor flux trajectory

CONCLUSION:

The proposed paper highlights to create a Simulink model of  DTC in induction motor drive. The DTC technique allows the decoupled control of torque and stator flux operate indipendently. The control process is simulated with the help of simpower system MATLAB Simulink block set and Sector determination with open-loop induction motor drive is obtained. In conventional DTC technique, high torque ripple is produced because the voltage space vector which are considered is applied for the whole switching period without considering the torque error value. This torque ripple can be minimized in order to achieve a smooth operation of the drive system and its performances, by changing the duty cycle ratio of the voltage vector which are selected during each switching cycle period, based on the stator flux position and torque error magnitude. This constitutes the basic of SVPWM technique. here simulate DTC scheme based on SVPWM technique and comparative study of conventional DTC-SVM scheme is derived and studied.

REFERENCES:

[1] Takahashi Isao, Noguchi Toshihiko, ,,’’A New Quick-Response IEEE Transactions on Industry Applications , Vol. IA-22No-5, Sept/Oct 1986.

 

Simulation Projects using Matlab/Simulink for BTech/MTech

Simulation Projects using Matlab/Simulink for BTech/MTech

A simulation is an imitation of the operation of a real-world process or system.The act of simulating something first requires that a model be developed; this model represents the key characteristics, behaviors and functions of the selected physical or abstract system or process. The model represents the system itself, whereas the simulation represents the operation of the system over time.

Simulation Projects List

Simulation is used in many contexts, such as simulation of technology for performance optimization, safety engineering, testing, training, education, and video games. Often, computer experiments are used to study simulation models. Simulation is also used with scientific modelling of natural systems or human systems to gain insight into their functioning, as in economics. Simulation can be used to show the eventual real effects of alternative conditions and courses of action. Simulation is also used when the real system cannot be engaged, because it may not be accessible, or it may be dangerous or unacceptable to engage, or it is being designed but not yet built, or it may simply not exist.

Simulation Projects

Performance comparison of PI & ANN based STATCOM for 132 KV transmission line  

International Conference on Electrical, Electronics, and Optimization Techniques (ICEEOT) – 2016

ABSTRACT: This paper presents simulation model of the 132KV transmission line with comparison of ANN based STATCOM and conventional PI based STATCOM. The STATCOM being the state-of-the-art VSC based dynamic shunt compensator in FACTS family is used now a days in transmission system for reactive power control, increase of power transfer capacity, voltage regulation etc. Such type of controller is applied at the middle of the transmission line to enhance the power transmission capacity of the line. The simulation result shows that the STATCOM is effective improve the power factor and voltage regulation for the 132kV line loading.

 KEYWORDS:

  1. STATCOM
  2. PI
  3. ANN control strategy
  4. MatLab simulink

 SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

 Fig 1: Schematic Representation of the Control Circuit.

 EXPECTED SIMULATION RESULTS:

 

Fig 2 1-phase current and voltage waveform using STATCOM

Fig3 Phase Current and Voltage waveform when the STATCOM is ON

Fig 4Phase Current and Voltage waveform when Load is Varied in the system

Fig 5 Phase Current and Voltage waveform when suddenly a Load is remove from the system at 0.4sec

Fig 6 3-phase current and voltage waveform using STATCOM

Fig 7 Active and Reactive power flow in Transmission system using STATCOM

Fig8 1-phase current and voltage waveform for STATCOM using ANN

Fig 9 Phase Current and Voltage waveform when the STATCOM is ON

Fig 10 1 Phase Current and Voltage waveform when Load is Varied in the System

Fig11 3-phase voltage and current waveform for STATCOM using ANN

CONCLUSION:

The paper present that the STATCOM bring the power factor to the unity thereby enhancing the power transfer capability by supplying or absorbing controllable amount of reactive power. By using a STATCOM with ANN controller and the Response time is faster comparing to the PI Controller because of this voltage regulation maintained within a limit. More over ANN Controlled STATCOM will improve the stability of the system and improve the dynamic performance of the system.

REFERENCES:

[1] B.Sing ,R.saha, A.Chandra “Static Synchronous Compensator (STATCOM): a review” IET Power Electronic 2008

[2] N.G Hingroni and I Gyugyi. “Understanding FACTS: Concepts and Technology of flexible AC Transmission System”, IEEE Press, New York, 2000.

[3] D.J Hanson, M.L.Woodhouse, C.Horwill “STATCOM: a new era of Reactive Compensation” Power Engineering Journal June 2002

[4] Mustapha Benghanem — Azeddine Draou” A NEW MODELLING AND CONTROL ANALYSIS OF AN ADVANCED STATIC VAR COMPENSATOR USING A THREE–LEVEL (NPC) INVERTER TOPOLOGY” Journal of ELECTRICAL ENGINEERING, VOL. 57, NO. 5, 2006, 285–290

[5] Jagdish Kumar, Biswarup Das, and Pramod Agarwal “ Modeling of 11- Level Cascade Multilevel STATCOM” International Journal of Recent Trends in Engineering, Vol 2, No. 5, November 2009

Dynamic Simulation of a Three-Phase Induction Motor Using Matlab Simulink

 

ABSTRACT:

The theory of reference frames has been effectively used as an efficient approach to analyze the performance of the induction electrical machines. This paper presents a step by step Simulink implementation of an induction machine using dq0 axis transformations of the stator and rotor variables in the arbitrary reference frame. For this purpose, the relevant equations are stated at the beginning, and then a generalized model of a three-phase induction motor is developed and implemented in an easy to follow way. The obtained simulated results provide clear evidence that the reference frame theory is indeed an attractive algorithm to demonstrate the steady-state behavior of the induction machines.

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 

 

Figure 1 the 3-phase induction motor Matlab/Simulink model

EXPECTED SIMULATION RESULTS:

 Figure 2 Torque speed characteristics for the 3 hp induction motor

Figure 3 Machine variables during free acceleration of a 3-hp induction motor

Figure 4 Torque speed characteristics for the 2250 hp induction motor

Figure 5 Machine variables during free acceleration of a 2250-hp induction motor

CONCLUSION:

In this paper, an implementation and dynamic modeling of a three-phase induction motor using Matlab/Simulink are presented in a step-by-step manner. The model was tested by two different ratings of a small and large induction motors. The two simulated machines have given a satisfactory response in terms of the torque and speed characteristics. Also, the model was evaluated by Matlab m-file coding program. Both methods have given the same results for the same specifications of the three phase induction motors used in this simulation. This concludes that the Matlab/Simulink is a reliable and sophisticated way to analyze and predict the behaviour of induction motors using the theory of reference frames.

 REFERENCES:

[1] P. C. Krause, O. Wasynczuk, S. D. Sudhoff “Analysis of Electric Machinery and Drive Systems”, IEEE Press, A John Wiley & Sons, Inc. Publication Second Edition, 2002.

[2] P.C. Krause and C. H. Thomas, “Simulation of Symmetrical Induction Machinery”, IEEE Transaction on Power Apparatus and Systems, Vol. 84, November 1965, pp. 1038-1053.

[3] P. C. Krause, “Analysis of Electric Machinery”, McGraw-Hill Book Company, 1986.

[4] D. C. White and H. H. Woodson, “Electromechanical Energy Conversion”, John Wiley and Sons, New York, 1959.

[5] M. L. de Aguiar, M. M. Cad, “The concept of complex transfer functions applied to the modeling of induction motors”, Power Engineering Society Winter Meeting, 2000, pp. 387–391.

[6] S. Wade, M. W. Dunnigan, B. W. Williams, “Modeling and simulation of induction machine

vector control with rotor resistance identification”, IEEE Transactions on Power Electronics, vol.

12, No. 3, May 1997, pp. 495–506.

Speed Controller of Switched Reluctance Motor

ABSTRACT

Fuzzy logic control has become an important methodology in control engineering. The paper suggest a Fuzzy Logic Controller (FLC) for controlling a speed of SRM drive. The impartial of this work is to compare the operation of P& PI based conventional controller and Artificial Intelligence (AI) based fuzzy logic controller to highlight the work of the effective controller. The present work focus on the design of a fuzzy logic controller for SRM speed control. The result of applying fuzzy logic controller to a SRM drive gives the best work and high robustness than a conventional P & PI controller. Simulation is carried out using Matlab/Simulink.

KEYWORDS: P Controller, PI Controller, Fuzzy Logic Controller, Switched Reluctance Motor

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM

Block diagram of SRM speed control

Figure 1. Block diagram of SRM speed control

 

 SIMULATION MODELS

Simulation model using P controller

Figure 2. Simulation model using P controller

Simulation model using PI controller.

Figure 3. Simulation model using PI controller.

Simulink model using FLC.

Figure 4. Simulink model using FLC.

SIMULATION RESULTS

Output flux.

Figure 5. Output flux.

Output current

Figure 6. Output current

Output torque

Figure 7. Output torque.

Speed

Figure 8. Speed.

 

CONCLUSION

Thus the SRM dynamic performance is forecasted and by using MATLAB/simulink the model is simulated. SRM has been designed and implemented for its speed control by using P, PI controller and AI based fuzzy logic controller. We can conclude from the simulation results that when compared with P & PI controller, the fuzzy Logic Controller meet the required output. This paper presents a fuzzy logic controller to ensure excellent reference tracking of switched reluctance motor drives. The fuzzy logic controller gives a perfect speed tracking without overshoot and enchances the speed regulation. The SRM response when controlled by FLC is more advantaged than the conventional P& PI controller.

 

REFERENCES

  1. Susitra D, Jebaseeli EAE, Paramasivam S. Switched reluctance generator – modeling, design, simulation, analysis and control -a comprehensive review. Int J Comput Appl. 2010; 1(210):975–8887.
  2. Susitra D., Paramasivam S. Non-linear flux linkage modeling of switched reluctance machine using MVNLR and ANFIS. Journal of Intelligent and Fuzzy Systems. 2014; 26(2):759–768.
  3. Susitra D, Paramasivam S. Rotor position estimation for a switched reluctance machine from phase flux linkage. IOSR–JEEE. 2012 Nov–Dec; 3(2):7.
  4. Susitra D, Paramasivam S. Non-linear inductance modeling of switched reluctance machine using multivariate non- linear regression technique and adaptive neuro fuzzy inference system. CiiT International Journal of Artificial Intelligent Systems and Machine Learning. 2011 Jun; 3(6).
  5. Ramya A, Dhivya G, Bharathi PD, Dhyaneshwaran R, Ramakrishnan P. Comparative study of speed control of 8/6 switched reluctance motor using pi and fuzzy logic controller. IJRTE; 2012

A New Control Strategy for Active and Reactive Power Control of Three-Level VSC Based HVDC System

ABSTRACT

This paper displays another control procedure no doubt and ready power control of three-level multipulse voltage source converter based High Voltage DC (HVDC) communication plan working at Fundamental Frequency Switching (FFS). A three-level voltage source converter change the regular two-level VSC and it is determined for the real and reactive power control is each of the four quarter task.

HVDC

Another control method is created for produce the ready power control by changing the beat width and by keeping the dc connect voltage regular. The enduring state and dynamic showing of HVDC plan joining two unique density arrange are shown for dynamic and responsive forces control.

VSC

Complete capacity of motor apply in the plan are decreased in contrast with two dimension VSCs. The killing of the HVDC plan is also increase as far as decreased music level even at important frequenccy exchanging.

BLOCK DIAGRAM: 1

Fig. 1 A three-level 24-Pulse voltage source converter based HVDC system

 CONTROL SCHEME

2

Fig. 2 Control scheme of three-level VSC based HVDC system using dynamic dead angle (β) Control

EXPECTED SIMULATION RESULTS

3

Fig. 3 Performance of rectifier station during simultaneous real and reactive power control of three-level 24-pulse VSC based HVDC system

4

Fig. 4 Performance of inverter station during simultaneous real and reactive power control of three-level 24-pulse VSC based HVDC system

5

Fig. 5 Variation of angles (δ) and (β) values of three-level 24-pulse VSC based HVDC system during simultaneous real and reactive power control

CONCLUSION

Another control method for three-level 24-beat voltage source converter setup has been planned for HVDC plan. The execution of this 24-beat VSC based HVDC  plan apply the control method has been exhibited in dynamic power control in bidirectional, free control of the ready power and power quality improvement.

HVDC PLAN

Another powerful dead point (β) control has been presented for three-level voltage source converter working at critical recurrence trade. In this control the HVDC plan activity is efficiently shown and furthermore an analysis of (β) esteem

ADAPTABLE

for different responsive power necessity and symphonious execution has been completed in detail. In this way, the determination of converter task locale is more adaptable as indicated by the necessity of the responsive power and power quality.

High-Efficiency MOSFET Transformerless Inverter for Non-isolated Microinverter Applications

ABSTRACT

Best in class low-control level metal– oxide– semiconductor field-affect transistor (MOSFET)- based transformerless photovoltaic (PV) inverters can achieve high capacity by using latest super union MOSFETs. In any case, these MOSFET-based inverter topologies encounter the suffering forcce of no less than one of these drawbacks:

MOSFET

MOSFET letdown danger from body diode pivot recovery, extended conduction event as a result of more devices, or low magnetics use. By part the conventional MOSFET based stage leg with a up to date inductor, this paper proposes a novel MOSFET-based stage leg plan to reduce these strain. In light of the proposed stage leg structure, a high viability single-arrange

PV

MOSFET transformerless inverter is shown for the PV microinverter applications. The pulsewidth change (PWM) direction and circuit undertaking rule are then describe. The ordinary mode and differential-mode voltage show is then displayed and consider for circuit structure. basic outcomes of a 250Whardware model are look to show the advantages of the proposed transformerless inverter on non-isolated two-sort out PV microinverter application.

 BLOCK DIAGRAM:

image001

Fig. 1. Two-stage nonisolated PV microinverter.

CIRCUIT DIAGRAM:

image002

Fig. 2. Proposed transformerless inverter topology with (a) separated magnetic and (b) integrated magnetics.

 EXPERIMENTAL RESULTS:

image003

Fig. 3. Output voltage and current waveforms.

image004

Fig. 4. PWM gate signals waveforms.

image005

Fig. 5. Inverter splitting inductor current waveform.

image006

Fig. 6. Waveforms of voltage between grid ground and DC ground (VEG ).

CONCLUSION

This paper proposes a MOSFET transformerless inverter with a novel MOSFET-based stage leg, which achieve:

1) high ability by apply super interchange MOSFETs and SiC diodes;

2) limited dangers from the MOSFET stage leg by part the MOSFET stage leg with up to date inductor and limiting the di/dt from MOSFET body diode switch recovery;

3) high magnetics use compare and past high ability MOSFET transformerless inverters in [21], [22], [25], which just have half magnetics use.

PWM

The proposed transformerless inverter has no dead-time necessity, basic PWM regulation for usage, and limited high-recurrence CM issue. A 250W hardware model has been planned, created, and tried in two-arrange non isolated micro inverter application. basic outcomes display that the proposed MOSFET transformerless inverter produce 99.01% height effectiveness at full load condition and 98.8% CEC capacity and furthermore produce around 98% attractive use. Because of the benefits of high strength, low CM voltage, and enhanced attractive use, the proposed topology is attractive for two-organize nonisolated PV microinverter applications and transformerless string inverter applications.

Cascaded Two-Level Inverter-Based Multilevel STATCOM for High-Power Applications

ABSTRACT

In this paper, a simple static var compensating system using a cascaded two-level inverter-located multilevel inverter is planned. The topology consists of two standard two-level inverters linked in cascade done open-end windings of a three-phase transformer. The dc link voltages of the inverters are controlled at different levels to get four-level operation. The simulation study is transported out in MATLAB/SIMULINK to conclude the work of the proposed scheme under balanced and unbalanced supply-voltage conditions.

CONTROL SCHEME

A lab prototype is grown to validate the simulation results. The control scheme is appreciate using the TMS320F28335 digital signal processor. Further, stregth behavior of the topology is checked. The dynamic model is developed and transfer functions are derived. The system act is consider for various operating conditions.

 KEYWORDS

  1. DC-link voltage balance
  2. Multilevel inverter
  3. Power quality (PQ)
  4. Static compensator (STATCOM)

 SOFTWARE:  MATLAB/SIMULINK

BLOCK DIAGRAM

image002

Fig. 1. Power system and the STATCOM model.

EXPECTED SIMULATION RESULTS

image004

Fig. 2. Frequency response ∆Vdc1(s) /∆δ1(s) at  iq0 =1.02 p.u., δ1=-0.902=178.90,R1=80 p.u., R2=60 p.u.

image006

Fig. 3. Root locus of the transfer function  ∆Vdc1(s) /∆δ1(s) at  iq0 = – 0.75 p.u., δ1=-0.5702=179.60,R1 =80 p.u., R2=60 p.u.

image008

Fig. 4. Reactive power control. (a) Source voltage and inverter current. (b) DC-link voltages of two inverters.

image010

Fig. 5. Operation during fault. (a) Grid voltages on the LV side of the transformer. (b) -axis negative-sequence current component idn. (c) -axis negative- sequence current component iqn.

image012

Fig. 6. Experimental result: Capacitive mode of operation. (a) Source voltage (50 V/div) and STATCOM current (5 A/div). (b) DC-link voltages of inverter-1 and inverter-2 (20 V/div). Time scale: 5 ms/div. (c) Harmonic spectrum of current.

image014

Fig. 7. Experimental result: Mode change from capacitive to inductive. (a) DC-link voltages of inverter-1 and inverter-2 (20 V/div). Time scale: 100 ms/div. (b) Source voltage (100 V/div) and STATCOM current (5 A/div) in steady state. Time scale: 100 ms/div.

CONCLUSION

DC-link voltage balance is one of the major spread in cascaded inverter-based STATCOMs. In this paper, a simple var compensating system is proposed for a cascaded two-level inverter- located multilevel inverter. The scheme provide regulation of dc-link voltages of inverters at asymmetrical levels and reactive power benefit. The work of the system is verify by simulation and test under balanced and unbalanced voltage conditions. Further, the cause for insecurity when there is a change in reference current is examined.

DYNAMIC

The dynamic model is grown and transfer functions are derived. System behavior is consider for various operating conditions. From the search, it is implicit that the system is a non minimum phase type, that is, post of the transfer function always distortion on the left half of the -plane. However, zeros shift to the right half of the -plane for certain operating conditions. For such a system, oscillatory insecurity for high controller gains exists.

REFERENCES

[1] N. G. Hingorani and L. Gyugyi, Understanding FACTS. Delhi, India: IEEE, 2001, Standard publishers distributors.

[2] B. Singh, R. Saha, A. Chandra, and K. Al-Haddad, “Static synchronous compensators (STATCOM): A review,” IET Power Electron., vol. 2, no. 4, pp. 297–324, 2009.

[3] H. Akagi, H. Fujita, S. Yonetani, and Y. Kondo, “A 6.6-kV transformerless STATCOM based on a five-level diode-clamped PWMconverter: System design and experimentation of a 200-V 10-kVA laboratory model,” IEEE Trans. Ind. Appl., vol. 44, no. 2, pp. 672–680, Mar./Apr. 2008.

[4] A. Shukla, A. Ghosh, and A. Joshi, “Hysteresis current control operation of flying capacitor multilevel inverter and its application in shunt compensation of distribution systems,” IEEE Trans. Power Del., vol. 22, no. 1, pp. 396–405, Jan. 2007.

[5] H. Akagi, S. Inoue, and T. Yoshii, “Control and performance of a transformerless cascaded PWM STATCOM with star configuration,” IEEE Trans. Ind. Appl., vol. 43, no. 4, pp. 1041–1049, Jul./Aug. 2007.