aThree-Phase Transformerless Shunt Active Power Filter with Reduced Switch Count for Harmonic Compensation in Grid-Connected Applications

 ABSTRACT:

Shunt active power filter is the preeminent solution against nonlinear loads, current harmonics and power quality problems. APF topologies for harmonic compensation use numerous high-power rating components and are therefore disadvantageous. Hybrid topologies combining low-power rating APF with passive filters are used to reduce the power rating of voltage source inverter. Hybrid APF topologies for high-power rating systems use a transformer with large numbers of passive components. In this paper, a novel four-switch two-leg VSI topology for a three-phase SAPF is proposed for reducing the system cost and size. The proposed topology comprises a two-arm bridge structure, four switches, coupling inductors, and sets of LC PFs. The third leg of the three-phase VSI is removed by eliminating the set of power switching devices, thereby directly connecting the phase with the negative terminals of the dc-link capacitor. The proposed topology enhances the harmonic compensation capability and provides complete reactive power compensation compared with conventional APF topologies. The new experimental prototype is tested in the laboratory to verify the results in terms of total harmonic distortion, balanced supply current, and harmonic compensation, following the IEEE-519 standard.

KEYWORDS:

1.      Harmonics

2.      hybrid topology

3.      nonlinear load

4.      power quality (PQ)

5.      Transformerless inverter

6.      Grid-connected system

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Proposed transformerless APF system

EXPECTED SIMULATION RESULTS:

  

                  

Fig. 2. Steady state operation of the proposed SAPF a) Utility voltage (THDv=4%) b) Utility current (THDi=4.1%) c) Load current (THDi=30.1%) d) Compensating filter current.

Fig. 3. a) DC voltage (50V/div). b) Filter current (100A/div) at filter switched ON (t=0.15).

Fig. 4. Starting performance of the proposed SAPF. a) Utility voltage (THDv=4%) b) Utility current (THDi=4.1%) c) Load current (THDi=30.1%) d) Compensating current at switched ON

Fig. 5. a) On-state and Off-state APF operations. b) Zoom image of utility line current (𝒊𝑺𝒂𝒃𝒄) at 5th and 7th order harmonics.

Fig. 6. Dynamic performance with the R-L load step-change waveforms of the proposed SAPF.

CONCLUSION:

In this paper, a novel three-phase reduced switch count and transformer-less APF circuit, operating with the function of active filtering and enhanced reactive power compensation. The main point of the proposed APF circuit topology, which uses a two-leg bridge structure and only four IGBT power devices in the three-phase power converter. Compared with the other existing topologies, the elimination of the transformer and minimum active and passive component contributes to a significant reduction in the manufacturing cost, volumetric size and weight. The proposed APF system is more robust, efficient and stable to improve the feasibility and harmonic propagation of the power distribution system. A detail analysis of the both the active filter inverter and passive filter, including the reactive power capability and filtering characteristics has been presented. The series LC tuned PF at the 5th and 7th order harmonic frequencies improves the harmonic mitigation performance. However, the series ac coupling inductors can overcome the fixed reactive power compensation caused by the defined value of the LC filter. The control algorithm can ensure the regulated sinusoidal voltage, phase amplitude, and low THD in the power distribution system, along with dc-link voltage control. The experimental and simulation results have verified the feasibility of the proposed APF topology and its excellent performance in terms of both transient and steady states responses to compensate selectively either the reactive power compensation, as well as in damping out the current harmonic distortion. Furthermore, the proposed APF system based on transformerless and power switching device reduced count configuration could be used in extensive applications, such as the grid-connected power converters, grid interfaced distributed energy sources, and so on.

 REFERENCES:

[1] S. D. Swain, P. K. Ray, and K. B. Mohanty, "Improvement of Power Quality Using a Robust Hybrid Series Active Power Filter," IEEE Transactions on Power Electronics, vol. 32, pp. 3490-3498, 2017.

[2] A. Javadi, A. Hamadi, L. Woodward, and K. Al-Haddad, "Experimental Investigation on a Hybrid Series Active Power Compensator to Improve Power Quality of Typical Households," IEEE Transactions on Industrial Electronics, vol. 63, pp. 4849-4859, 2016.

[3] W. U. Tareen, S. Mekhilef, M. Seyedmahmoudian, and B. Horan, "Active power filter (APF) for mitigation of power quality issues in grid integration of wind and photovoltaic energy conversion system," Renewable and Sustainable Energy Reviews, vol. 70, pp. 635-655, 4// 2017.

[4] J. Solanki, N. Fröhleke, and J. Böcker, "Implementation of Hybrid Filter for 12-Pulse Thyristor Rectifier Supplying High-Current Variable-Voltage DC Load," IEEE Transactions on Industrial Electronics, vol. 62, pp. 4691-4701, 2015.

[5] L. Asiminoaei, C. Lascu, F. Blaabjerg, and I. Boldea, "Performance Improvement of Shunt Active Power Filter With Dual Parallel Topology," IEEE Transactions on Power Electronics, vol. 22, pp. 247-259, 2007.

Development of 10kW Three-Phase Grid Connected Inverter

ABSTRACT:

In this paper, modeling, simulation and experimental study of a 10kW three-phase grid connected inverter are presented. The mathematical model of the system is derived, and characteristic curves of the system are obtained in MATLAB with m-file for various switching frequencies, dc-link voltages and filter inductance values. The curves are used for parameter selection of three-phase grid connected inverter design. The parameters of the system are selected from these curves, and the system is simulated in Simulink. Modeling and simulation results are verified with experimental results at 10kW for steady state response, at 5kW for dynamic response and at −3.6 kVAr for reactive power. The inverter is controlled with Space Vector Pulse Width Modulation technique in d-q reference frame, and dSPACE DS1103 controller board is used in the experimental study. Grid current total harmonic distortion value  and efficiency are measured 3.59% and 97.6%, respectively.

KEYWORDS:

1.      Grid Connected Inverter

2.      Inverter Modeling

3.      Space Vector Pulse Width Modulation

4.      Total Harmonic Distortion

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Block diagram of the grid connected inverter.

EXPECTED SIMULATION RESULTS:

              

Fig. 2. THD variation of the grid current for V_dc = 650 V.

Fig. 3. THD variation of the grid current for f_sw = 3 kHz.

Fig. 4. THD variation of the grid current for fsw = 9 kHz.

Fig. 5. Three-phase grid currents and voltage for fsw = 3 kHz.

Fig. 6 d-q components of the grid current for fsw = 3 kHz

Fig. 7. Three-phase grid currents and voltage for fsw = 9 kHz

Fig. 8. d-q components of the grid current for fsw = 9 kHz.

Fig. 9. d-q components of grid current.

CONCLUSION:

In this study, performance of a 10kW three-phase grid connected inverter is investigated for various filter inductance values, DC-link voltages and switching frequencies. The system is modeled in m-file, thus characteristic curves of the inverter are obtained for different parameters. The THD values of grid current for 3 kHz and 9 kHz with 650V DC-link voltage are 10.22%and 3.41%. For verification of the modeling results, the system is simulated in Simulink. The control algorithm is implemented in Embedded Matlab Function in the simulation. The results are compared at 3 kHz and 9 kHz switching frequency, and modeling results are verified with simulation results that are 10.22% are 3.44%. In order to verify the modeling and simulation results, a laboratory prototype that is controlled by dSPACE DS1103 control board is realized. In the experimental study, THD values are measured as 10.68 and 3.59%. Furthermore, dynamic response and reactive power generation capability of the inverter are presented. The experimental results verify the modeling and simulation results. This verification shows that the system can be designed for various system and control parameters using the design curves. The study is realized for 10kW power but it is possible to obtain the characteristic curves for differen power values. According to results, the switching frequency or filter inductance value should be high to meet THD limit. Furthermore, efficiency is another important performance indicator. The efficiency at rated power and the european efficiency of the inverter is 97.6% and 97.2%  at 9 kHz.

REFERENCES:

[1] F. Blaabjerg, M. Liserre and K. Ma: “Power Electronics Converters for Wind Turbine Systems”, IEEE Transactio on Industry Applications, vol.48, pp. 708-719, 2012.

[2] F. Blaabjerg, Z. Chen, S.B. and Kjaer: “Power Electronics as Efficient Interface in Dispersed Power Generation Systems”, IEEE Transactions on Power Electronics, vol. 19,  pp. 1184-1194, 2004.

[3] J.M. Carrasco, L.G. Franquelo, J.T. Bialasiewicz, E. Galvan, R.C.P. Guisado, M.A.M. Prats, J.I. Leon and N.M. Alfonso:  “Power-Electronic Systems for the Grid Integration   of Renewable Energy Sources: A Survey”, IEEE Transactions  on Industrial Electronics, vol. 53, pp. 1002-1016, 2006. 

[4] C. Ramonas and V. Adomavicius: “Research of the Converte  Possibilities in the Grid-tied Renewable Energ  Power Plant”, Elektronika IR Elektrotechnika, vol. 19, pp  37-40, 2013.

[5] D. Meneses, F. Blaabjerg, O. Garcia and J.A. Cobos: “Review and Comparison of Step-Up Transformerless Topologies for Photovoltaic AC-Module Application”, IEEE  Transactions on Power Electronics, vol. 28, pp. 2649-2663,  2013.

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

ABSTRACT:

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.

KEYWORDS:

1.      PWM

2.      SVPWM

3.      Three phase inverter

4.      Total harmonic distortion

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

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

EXPECTED SIMULATION RESULTS:

             

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.

CONCLUSION:

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.

REFERENCES:

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.

D. 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.

T. Erfidan, S. Urugun, Y. Karabag and B. Cakir. 2004. New Software implementation of the Space Vector Modulation. Proceedings of IEEE Conference. pp.1113-1115.

D. Rathnakumar, J. Lakshmana Perumal and T. Srinivasan. 2005. A New software implementation of  space vector PWM. Proceedings of IEEE Southeast conference. pp.131-136.

B. Hariram and N. S. Marimuthu. 2005. Space vector switching patterns for different applications- A comparative analysis. Proceedings of IEEE conference. pp. 1444-1449.

Modeling and Simulation of a Distribution STATCOM (D-STATCOM) for Power Quality Problems-Voltage Sag and Swell Based on Sinusoidal Pulse Width Modulation (SPWM)

ABSTRACT:

This paper presents the systematic procedure of the modeling and simulation of a Distribution STATCOM (DSTATCOM) for power quality problems, voltage sag and swell based on Sinusoidal Pulse Width Modulation (SPWM) technique. Power quality is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure of end use equipments. The major problems dealt here is the voltage sag and swell. To solve this problem, custom power devices are used. One of those devices is the Distribution STATCOM (D-STATCOM), which is the most efficient and effective modern custom power device used in power distribution networks. D-STATCOM injects a current in to the system to correct the voltage sag and swell.The control of the Voltage Source Converter (VSC) is done with the help of SPWM. The proposed D-STATCOM is modeled and simulated using MATLAB/SIMULINK software.

KEYWORDS:

1.      Distribution STATCOM (D-STATCOM)

2.      MATLAB/SIMULINK

3.      Power quality problems

4.       Sinusoidal Pulse  Width Modulation (SPWM)

5.       Voltage sag and swell

6.       Voltage  Source Converter (VSC)

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. Schematic representation of the D-ST A TeOM for a typical custom

power application.

EXPECTED SIMULATION RESULTS:

Fig. 2. Voltage V_rms at load point, with three-phase fault: (a) Without DSTATCOM

and (b) With D-STATCOM, 750I-lf .

Fig. 3. Voltage v_rms at load point, with three phase-ground fault: (a)

Without D-STATCOM and (b) With D-STATCOM.

Fig. 4. Voltage V_rms at load point, with line-ground fault: (a) Without DSTATCOM

and (b) With D-STATCOM.

Fig. 5. Voltage v_rms at load point, with line-line fault: (a) Without DSTATCOM

and (b) With D-STATCOM.

Fig. 6. Voltage v_rms at load point, with line-line-ground fault: (a) Without

D-STATCOM and (b) With D-STATCOM.

CONCLUSION:

This paper has presented the power quality problems such as voltage sags and swell. Compensation techniques of custom power electronic device D-ST ATCOM was presented. The   design and applications of D-STATCOM for voltage sags, swells and comprehensive results were presented. The Voltage Source Convert (VSC) was implemented with the help of Sinusoidal Pulse Width Modulation (SPWM). The control scheme was tested under a wide range of operating conditions, and it was observed to be very robust in every case. For modeling and simulation of a D-ST ATCOM by using the highly developed graphic facilities available in MA TLAB/SIMULINK were used. The simulations carried out here showed that the D-STATCOM provides relatively better voltage regulation capabilities.

REFERENCES:

[I] O. Anaya-Lara, E. Acha, "Modeling and analysis of custom power  systems by PSCAD/EMTDC," IEEE Trans. Power Delivery, vol. 17, no .I, pp. 266-272, January 2002.

[2] S. Ravi Kumar, S. Sivanagaraju, "Simualgion of D-Statcom and DVR in  power system," ARPN jornal of engineering and applied science, vol. 2,   no. 3, pp. 7-13, June 2007.

[3] H. Hingorani, "Introducing custom power", IEEE Spectrum, vol. 32, no.6, pp. 41-48, June 1995.

[4] N. Hingorani, "FACTS-Flexible ac transmission systems," in Proc. IEE 5th Int Conf AC DC Transmission, London, U.K., 1991, Conf Pub.  345, pp. 1-7.

[5] Mahesh Singh, Vaibhav Tiwari, "Modeling analysis and soltion to  power quality problems," unpublished.