Powеr Quality Improvement In Powеr Systеm By Using SVPWM Based Static Synchronous Sеriеs Compеnsator


 Power quality improvement is an important issue in power system. Flexible AC Transmission (FACTS) devices are commonly used for solving problems related to power quality and improving it. In this paper a synchronous static series compensator (SSSC) is used for control and modulation of power flow in a transmission line. The Pulse Width Modulation (PWM) and SVPWM control techniques are employed in SSSC. The active performance of SSSC is evaluated using Matlab/Simulink environment. The simulation results validate that the power quality is enhanced properly using SSSC.


  1. Power Quality
  2. FACTS
  3. PWM
  4. SVPWM
  5. SSSC




 Figure 1. Functional model of SSSC.



 Figure 2. (a) Source voltage (b) Source current without SSSC.

Figure 3. (a) Load voltage (b) Load current without SSSC.

Figure 4. (a) Source voltage (b) Source current with SSSC.

Figure 5. (a) Load voltage (b) Load current with SSSC.

Figure 6. (a) Source voltage (b) Source current with SVPWM SSSC.

Figure 7. (a) Load voltage (b) Load current with SVPWM SSSC.

Figure 8. FFT analysis of (a) Source voltage (b) Source current-without SSSC.

Figure 9. FFT analysis of (a) Load voltage (b) Load current –without SSSC.

Figure 10. FFT analysis of (a) Source voltage (b) Source current with SSSC.

Figure 11. FFT analysis of (a) Load voltage (b) Load current with SSSC.

Figure 12. FFT analysis of (a) source voltage and (b) source current using SVPWM SSSC.

Figure 13. FFT analysis of (a) Load voltage and (b) Load current using SVPWM SSSC.


 In this paper the problem of modulation and control of power flow in transmission line is carried out by using SSSC with PWM and SVPWM techniques. The performance of SSSC is validated using Matlab/Simulink software. Thus, simulation results and THD analysis shows that by using SVPWM based SSSC power quality gets improved more as compared to the SPWM based SSSC. Hence SVPWM technique proves better as compared to that of the SPWM technique for power quality improvement.


[1] N.G. Hingorani and L. Gyugyi, “Undеrstanding FATCS concеpts andtеchnology of flеxiblе ac transmission systеm”,Nеw York, NY: IЕЕЕ prеss, 2000.

[2] “Static Synchronous Compensator,” CIGRE, Working group 14.19, 1998.

[3] Laszlo Gyugyi, Colin D. Schaudеr, and Kalyan K. Sеn, “static synchronous sеriеs compеnsator: a solid-statе approach to thе sеriеs compеnsation of transmission linеs”, IЕЕЕ Transactions on powеr dеlivеry, Vol. 12, No. 1, January 1997.

[4] Vaishali M. Morе, V.K. Chandrakar, “Powеr systеm pеrformancеs improvеmеnt by using static synchronous sеriеs compеnsator”, intеrnational confеrеncе on Advancеs in Еlеctrical, Еlеctronics,Informantion, Communication and Bio-Informatics 978-1-4673-9745-2©2016 IЕЕЕ.

[5] M. Farhani, “Damping of subsynchronous oscillations in powеr systеm by using static synchronous sеriеs compеnsator”,IЕT Gеnr. Distrib.vol.6.Iss.6.pp.539-544,2012.

Simulation and Comparison of SPWM and SVPWM Control for Three Phase Inverter


A voltage source inverter is commonly used to supply a three-phase induction motor with variable frequency and variable voltage for variable speed applications. A suitable pulse width modulation (PWM) technique is employed to obtain the required output voltage in the line side of the inverter. The different methods for PWM generation can be broadly classified into Triangle comparison based PWM (TCPWM) and Space Vector based PWM (SVPWM). In TCPWM methods such as sine-triangle PWM, three phase reference modulating signals are compared against a common triangular carrier to generate the PWM signals for the three phases. In SVPWM methods, a revolving reference voltage vector is provided as voltage reference instead of three phase modulating waves. The magnitude and frequency of the fundamental component in the line side are controlled by the magnitude and frequency, respectively, of the reference vector. The highest possible peak phase fundamental is very less in sine triangle PWM when compared with space vector PWM. Space Vector Modulation (SVM) Technique has become the important PWM technique for three phase Voltage Source Inverters for the control of AC Induction, Brushless DC, Switched Reluctance and Permanent Magnet Synchronous Motors. The study of space vector modulation technique reveals that space vector modulation technique utilizes DC bus voltage more efficiently and generates less harmonic distortion when compared with Sinusoidal PWM (SPWM) technique. In this paper first a model for Space vector PWM is made and simulated using MATLAB/SIMULINK software and its performance is compared with Sinusoidal PWM. The simulation study reveals that Space vector PWM utilizes dc bus voltage more effectively and generates less THD when compared with sine PWM.


  1. PWM
  2. SVPWM
  3. Three phase inverter
  4. Total harmonic distortion



Figure-1. Block diagram of SPWM inverter fed induction motor.


Figure-2a. Response of line voltage in SPWM.

Figure-3. Response of line voltage in SPWM.

Figure-4a. Response of line current in SPWM.

Figure-5b. Response of line current in SPWM.

Figure-6. Response of rotor speed in SPWM.

Figure.7. Response of torque in SPWM.

Figure-8. Response of line voltage in SVPWM.

Figure-9. Response of line current in SVPWM.

Figure-10. Response of rotor speed in SVPWM.

Figure-11. Response of torque in SVPWM.


Space vector Modulation Technique has become the most popular and important PWM technique for Three Phase Voltage Source Inverters for the control of AC Induction, Brushless DC, Switched Reluctance and Permanent Magnet Synchronous Motors. In this paper first comparative analysis of Space Vector PWM with conventional SPWM for a two level Inverter is carried out. The Simulation study reveals that SVPWM gives 15% enhanced fundamental output with better quality i.e. lesser THD compared to SPWM. PWM strategies viz. SPWM and SVPWM are implemented in MATLAB/SIMULINK software and its performance is compared with conventional PWM techniques. Owing to their fixed carrier frequencies cfin conventional PWM strategies, there are cluster harmonics around the multiples of carrier frequency. PWM strategies viz. Sinusoidal PWM and SVPWM utilize a changing carrier frequency to spread the harmonics continuously to a wideband area so that the peak harmonics are reduced greatly.


Zhenyu Yu, Arefeen Mohammed, Issa Panahi. 1997. A Review of Three PWM Techniques. Proceedings of the American Control Conference Albuquerque, New Mexico. pp. 257-261.

  1. G. Holmes and T. A. Lipo. 2003. Pulse Width Modulation for Power Converters: Principles and Practice. M.E. El-Hawary, Ed. New Jersey: IEEE Press, Wiley- Interscience. pp. 215-313.
  2. Erfidan, S. Urugun, Y. Karabag and B. Cakir. 2004. New Software implementation of the Space Vector Modulation. Proceedings of IEEE Conference. pp.1113-1115.
  3. Rathnakumar, J. Lakshmana Perumal and T. Srinivasan. 2005. A New software implementation of space vector PWM. Proceedings of IEEE Southeast conference. pp.131-136.
  4. Hariram and N. S. Marimuthu. 2005. Space vector switching patterns for different applications- A comparative analysis. Proceedings of IEEE conference. pp. 1444-1449.

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


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].


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




 Fig.1. DTC block diagram



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


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.


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


Simplified SVPWM Algorithm for Neutral Point Clamped 3-level Inverter fed DTC-IM Drive



In this paper, a simplified space vector pulse width modulation (SVPWM) method has been developed for three phase three-level voltage source inverter fed to direct torque controlled (DTC) induction motor drive. The space vector diagram of three-level inverter is simplified into two-level inverter. So the selection of switching sequences is done as conventional two-level SVPWM method. Where in conventional direct torque control (CDTC), the stator flux and torque are directly controlled by the selection of optimal switching modes. The selection is made to restrict the flux and torque errors in corresponding hysteresis bands. In spite of its fast torque response, it has more flux, torque and current ripples in steady state. To overcome the ripples in steady state, a space vector based pulse width modulation (SVPWM) methodology is proposed in this paper. The proposed SVPWM method reduces the computational burden and reduces the total harmonic distortion compared with 2-level one and the conventional one also. To strengthen the voice simulation is carried out and the corresponding results are presented.


  1. SVPWM
  2. DTC



Fig.1 Block diagram of proposed DTC drive.


 Fig 2 steady state plots of speed, torque, stator currents and stator flux for CDTC based IM drive at 1200 rpm.

Fig 3 Harmonic Spectrum of stator current along with THD.

Fig. 4 Simulation results of 2-level SVPWM based DTC: steady-state plots at 1200 rpm.

Fig. 5 Harmonic Spectrum of stator current along with THD for 2-Level SVPWM based DTC-IM drive.

Fig. 6 Starting transients in speed, torque, currents and flux for simplified SVPWM algorithm based 3-level inverter fed DTC-IM.

Fig. 7 Steady state plots of speed, torque, currents and flux for simplified SVPWM algorithm based 3-level inverter fed DTC-IM.

Fig. 8 Harmonic spectra of steady state line current for simplified SVPWM algorithm based 3-level inverter fed DTC-IM.

Fig. 9 transients during step change in load for simplified SVPWM algorithm based 3-level inverter fed DTC-IM: a 30 N-m load is applied at 0.5 sec.

Fig. 10 Phase and line voltages during a step change in load for simplified SVPWM algorithm based 3-level inverter fed DTC-IM: a 30 N-m load is applied at 0.5 sec.

Fig. 11 Transients in speed, torque, currents and flux during speed reversal for simplified SVPWM algorithm based 3-level inverter fed DTC-IM (speed is changed from 1200 rpm to -1200 rpm at 0.7 s)

Fig. 12 Transients in speed, torque, currents and flux during speed reversal for simplified SVPWM algorithm based 3-level inverter fed DTC-IM (speed is changed from -1200 rpm to +1200 rpm at 1.35 s)

Fig. 13 Four-quadrant operation of proposed simplified SVPWM algorithm based 3-level inverter fed induction motor drive.


In this paper, a simplified SVPWM algorithm is presented for three-phase three-level inverter fed DTC drive. The proposed algorithm generates the switching pulses similar to a two-level inverter based SVPWM algorithm. Thus, the proposed algorithm reduces the complexity involved in the existing PWM algorithms. To validate the proposed PWM algorithm, numerical simulation studies have been carried out and results are presented. From the simulation results, it can be concluded that the three-level inverter fed DTC drive gives reduced steady state ripples and harmonic distortion.


[1] F. Blaschke “The principle of field orientation as applied to the new transvector closed loop control system for rotating-field machines,” Siemens Review, 1972, pp 217-220.

[2] Isao Takahashi and Toshihiko Noguchi, “A new quick-response and high-efficiency control strategy of an induction motor,” IEEE Trans. Ind. Applicat., vol. IA-22, no.5, Sep/Oct 1986, pp. 820-827.

[3] Domenico Casadei, Francesco Profumo, Giovanni Serra, and Angelo Tani, “FOC and DTC: Two Viable Schemes for Induction Motors Torque Control” IEEE Trans. Power Electron., vol. 17, no.5, Sep, 2002, pp. 779-787.

[4] D. Casadei, G. Serra and A. Tani, “Implementation of a direct torque control algorithm for induction motors based on discrete space vector modulation” IEEE Trans. Power Electron., vol.15, no.4, Jul 2000, pp.769-777.

[5] Nabae, A., Takahashi, I., and Akagi, H, “A neutral-point clamped PWM inverter’, IEEE-Trans. Ind. Appl., 1981, 17, (5), pp.518-523.

Simulation Analysis of SVPWM Inverter Fed Induction Motor Drives


In this paper represent the simulation analysis ofspace vector pulse width modulated(SVPWM) inverter fedInduction motor drives. The main objective of this paper isanalysis of Induction motor with SVPWM fed inverter and harmonic analysis of voltages & current. for control of IMnumber of Pulse width modulation (PWM) schemes are used tofor variable voltage and frequency supply. The most commonlyused PWM schemes for three-phase voltage source inverters(VSI) are sinusoidal PWM (SPWM) and space vector PWM(SVPWM). There is an increasing trend of using space vectorPWM (SVPWM) because of it reduces harmonic content involtage, Increase fundamental output voltage by 15% & smoothcontrol of IM. So, here present Modeling & Simulation ofSVPWM inverter fed Induction motor drive inMATLAB/SIMULINK software. The results of Total HarmonicDistortion (THD), Fast Fourier Transform (FFT) of current areobtained in MATLAB/Simulink software.


  1. Inverter
  2. VSI
  3. SPWM
  4. SVPWM
  5. IM drive



  Figure 1.Simulation Block Diag. of SVPWM Three level inverter with IM load



Figure 2 Inverter Line voltage

Figure 3 Inverter Line currents

Figure 4 Stator Current

Figure 5 Rotor Current

Figure 6 Mechanical Speed

Figure 7 Torque

Figure 8 Harmonic (FFT) Analysis of Line current


The SVPWM Inverter fed induction motor driveModeling & then simulation is done in MATLAB/SIMULINK 12. From simulation results of THD & FFT analysis concluded that SVPWM technique is better overall PWM techniques which gives less THD in Inverter current 4.89%., which under the permissible limit.


[1] A. R. Bakhshai H. R. Saligheh Rad G. Joos, space vectormodulation based on classification method in three-phasemulti-level voltage source inverters, IEEE 2001

[2] Bimal K Bose, modern power electronics and ac drives © 2002Prentice hall ptr.

[3] Dorin O. Neacsu, space vector modulation –An introductiontutorial at IECON2001 IEEE 2001

[4] Fei Wang, Senior Member, “Sine-Triangle versus Space-VectorModulation for Three-Level PWM Voltage-Source Inverters”,IEEE transactions on industry applications, vol. 38, no. 2,March/April 2002. The 27th Annual Conference of the IEEEIndustrial Electronics Society

[5] F. Wang, Senior, Sine-Triangle vs. space vector modulation forthree-level voltage source inverters ,IEEE 2000