Comparison of Control Algorithms for Shunt Active Filter for Harmonic Mitigation

ABSTRACT:

 Shunt Active Filter generates the reference current, that must be provided by the power filter to compensate harmonic currents demanded by the load. This paper presents different types of SRF methods for real time regeneration of compensating current for harmonic mitigation. The three techniques analyzed are the Synchronous Reference Frame Theory (SRF), SRF theory without synchronizing circuit like phase lock loop (PLL) also called instantaneous current component theory and finally modified SRF theory. The performance of Shunt Active Power Filter in terms of THD (Total Harmonic distortion) of voltage and current is achieved with in the IEEE 519 Standard. The comparison of all methods is based on the theoretical analysis and simulation results obtained with MATLAB/SIMULINK

KEYWORDS:

1.      Synchronous Reference Frame

2.      Instantaneous current component theory

3.      Modified SRF

4.      Active Filter

5.      Harmonics

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

CONCLUSION:

This paper presents the compensation performance of all the different SRF techniques under sinusoidal voltage source condition as shown in table-1. Results are similar with gained source THD under IEEE 519, but under various filter type the chebyshev type filter is having superior performance compare to Butterworth filter for all methods. The Synchronous Reference Frame method is one of the most common and performing methods for detection of harmonics in active filters. An Improved Synchronous Reference Frame Method for the control of active power filters was presented. It is called Filtered Modified Reference Frame Method (FMRF) and is based on the same principle as the Synchronous Reference Frame method. However, this new method explores the fact that the performance of the active filter to isolate harmonics depends on the speed of the system that determines the rotating reference frame, but doesn’t depend on its position. So, the delay introduced by the ac voltage filters, used for the detection of the reference frame, has no influence on the detection capability of the method. Compared with other methods, this new method presents some advantages due to its simplicity and its rudeness to perturbations on the ac network.

REFERENCES:

[1] M.J. Newman, D.N.Zmood, D.G.Holmes, “Stationary frame harmonic reference generation for active filter systems”, IEEE Trans. on Ind. App., Vol. 38, No. 6, pp. 1591 – 1599, 2002.

[2] V.Soares,P.Verdelho,G.D.Marques,“ An instantaneous active reactive current component method for active filters” IEEE Trans. Power Electronics, vol. 15, no. 4, July- 2000, pp. 660–669.

[3] G.D.Marques, V.Fernao Pires, Mariusz Mlinowski, and Marian Kazmierkowski, “An improved synchronous Reference Method for active filters,” the International conference on computer as a tool, EUROCON 2007, Warsaw, September - 2007, pp. 2564-2569. 

Comparison of Controllers for Power Quality Improvement Employing Shunt Active Filter

ABSTRACT:

In this paper, an implementation of shunt active filter for current harmonics compensation in order to achieve power quality improvement under non linear load condition is proposed. Shunt active filter makes the source current almost sinusoidal under non linear load condition by eliminating current harmonics. Controller generates the reference current and it is compared with actual current. PWM current controller controls the switch of the shunt active filter circuit. Shunt active filter eliminates the undesired current harmonics by injecting current into the system thereby reduces total harmonic distortion and improves power factor. The main objective of the project is to find the most suitable control method that is capable of reducing total harmonic distortion in the source current under non linear load condition. Fast and precise control loop is needed in order to assure the desired power quality. Three control techniques have been proposed: PI controller, Hysteresis current controller, Fuzzy logic controller. The system is modeled using Matlab/Simulink and simulation results prove that the source current harmonics can be reduced and power factor can be improved. The comparative performance of the proposed three controllers is also presented.

KEYWORDS:

1.      Power Quality

2.      Shunt Active Filter

3.      Voltage Source Inverter

4.      PI

5.      Hysteresis Current Controller

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

EXPECTED SIMULATION RESULTS:

CONCLUSION:

In this paper, the design of shunt active filter to compensate harmonics in the power system based on three control techniques were presented and compared. All the control techniques make the source voltage and source current to be in phase. In the first control scheme the capacitor voltage is regulated based on reference voltage and provides compensation for the reduction of harmonics in the source current, the second one provides compensation based on reference current generated from the fourier transform of load current, while the third one considers the active filter controlled by fuzzy logic controller which is suitable for uncertainty condition. Among the three proposals the fuzzy logic control technique [7] doesn't need any mathematical model, reduces total harmonic distortion in a better way and provides good performance and robust to the parameter uncertainties compared with other strategies.

REFERENCES:

[1] David A .Torrey, Adel M. A . M. AI-Zamel "Single-phase active power filters for multiple nonlinear loads" IEEE Transactions on Power Electronics, Vol. 1 0, No. 3, May 1 995, pp 263-2 72.

[2] B.Singh ,K.Ai-Haddad, and A.chandra , " A review of active filters for power quality improvement" IEEE Transaction on Industrial electronics, vol 46,Issue no. 5, Oct-1999, pp 960-971.

[3] Fabiana Pottker de Souza, and Ivo Barbi, " Single-phase active power filters for distributed power factor correction", Power Electronics Specialists Conference 2000, PESC 00, Vol.l , pp500-505.

[4] M. EI- Habrouk, M.K. Darwish and P. Mehta "Active filter - A review" Electric Power Applications, lEE Proceedings, Vol 1 4 7, Sep 2000, Issue 5, pp 403-413.

Control Strategy for Three Phase Voltage Source PWM Rectifier based on the SVM

Control Strategy for Three Phase Voltage Source PWM Rectifier based on the SVM

ABSTRACT:

This paper proposes the space vector pulse width modulation control scheme for three phase voltage source PWM rectifier. The control system based on SVPWM includes two PI controllers which are used to regulate the AC currents and DC link voltage. The proposed control can stabilize the minimum of the systems storage function at the desired equilibrium point determined by unity power factor and sinusoidal current on the AC side, and constant output voltage on the DC side. So the stable state performance and robustness against the load’s disturbance of PWM rectifiers are both improved. The result simulation shows feasibility of this strategy.

KEYWORDS:

1.      PWM rectifier

2.      SVPWM

3.      Power factor.

SOFTWARE: MATLAB/SIMULINK

CIRCUIT SCHEMATIC DIAGRAM:

EXPECTED SIMULATION RESULTS:

CONCLUSION:

In this paper, a control strategy of the three phase voltage source PWM rectifier based on the space vector modulation is proposed. The control system based on SVPWM includes two PI controllers which are used to regulate the AC current and an outer DC voltage loop is composed by IP controller with anti-windup strategy. The simulation results shows a good performance of proposed strategy method at start-up and during load variations, providing a good regulation of output DC voltage, sinusoidal input AC current and unitary power factor.

REFERENCES:

[1] S. Mazumder, DSP based implementation of a PWM AC/DC/AC converter using space vector modulation with primary emphasis on the analysis of the practical problems involved, in 12th Applied Power Electronics Conference, 1997, pp. 306-312.

[2] S. Hansen, M. Malinowski, F. Blaabjerg, M.P. Kazmierkowski, Control strategies for PWM rectifier without line voltage sensors, in Proc. IEEE-APEC conf. vol. 2, pp. 832-839, 2000.

[3] Li Yabin, Li Heming, P. Yonglong, A unity power factor three phase buck type SVPWM rectifier based on direct phase control scheme, Mobile Robots,

Power Electronics and Motion Control Conference, 2006, IPEMC’06, vol. 8, no. 2, pp. 520-531.

[4] C.T. Pan and J. Shieh, New space vector control strategies for three-phase step-up/down AC/DC converter, IEEE Trans. On Industriel Electronics, vol. 47, pp. 25-35, February 2000.

[5] S.R. Bowes, S. Grewal, Novel harmonic elimination PWM control strategies for three-phase PWM inverters using space vector techniques, Electric Power Applications, IEE proceeding, vol. 146, pp. 451-495, Sept. 1999.

Z-SOURCE INVERTER WITH A NEW SPACE VECTOR PWM ALGORITHM FOR HIGH VOLTAGE GAIN

Z-SOURCE INVERTER WITH A NEW SPACE VECTOR PWM ALGORITHM FOR HIGH VOLTAGE GAIN

ABSTRACT:

 This paper presents a methodology to apply a novel space vector pulse width modulation control for three phase Z-source inverter. The space vector modulation for the conventional voltage source inverter is modified so that the additional shoot-through states are inserted within the zero states. So zero voltage time period is diminished for generating a shoot-through time, and active states are unchanged. The shoot-through states are evenly distributed to each phase within zero state. The shoot-through time is used for controlling the dc link voltage boost and hence the output voltage boost of the inverter. This new method provides a high voltage gain at higher modulation index. The proposed algorithm is verified with simulation and experiment. MatLab/Simulink is used for simulating the complete circuit with RL load. The frequency spectra of the output voltage and current are explored.

KEYWORDS:

1.      voltage gain

2.      Z-source inverter

3.      Space vector PWM

4.      Current source inverter

5.       Total harmonic distortion.

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

EXPECTED SIMULATION RESULTS:

CONCLUSION:

A novel modified space vector PWM control method was carried out in this paper for three phase Z-source inverter. In this modified SVPWM method four shoot-through states were inserted in each sector for controlling the output voltage of Z-source inverter. The output AC voltage obtained from ZSI is no longer limited and can be boosted beyond the limit imposed by conventional VSI. Using MatLab/Simulink software package the simulation was performed to validate the proposed algorithm. The frequency spectra and the total harmonic distortion of the load current and voltages were obtained. Also the presented concepts were verified experimentally using a laboratory prototype.

REFERENCES:

[1] F. Z. Peng. 2003. Z-Source Inverter. IEEE Transactions on Industry Applications. 39(2): 504-510.

[2] P. C. Loh, D. M. Vilathgamuwa, Y. S. Lai, G. T. Chua and Y. W. Li. 2005. Pulse-width modulation of Z-source inverters. IEEE Trans. Power Electronics. 20: 1346-1355.

[3] Mohan N., W. P. Robbin and T. Undeland. 1995. Power Electronics: Converters, Applications and Design. 2^nd Edition, Wiley.

[4] F. Z. Peng, M. Shen and Z. Qian. 2005. Maximum Boost Control of the Z-source Inverter. IEEE Trans. Power Electronics. July. 20(4): 833-838.

[5] Miaosen shen, Jin Wang, Alan Joseph, Fang Z. Peng, Leon m. Tolbert and Donald J. Adams. 2006. Constant Boost Control of the Z-Source Inverter to Minimize Current Ripple and Voltage Stress. IEEE Transactions on Industry Applications. 42(3): 770-778.

Simulation and Analysis of Zero Voltage Switching PWM Full Bridge Converter

Simulation and Analysis of Zero Voltage Switching PWM Full Bridge Converter

ABSTRACT:

In the conventional zero voltage switching full bridge converter the introduction of a resonant inductance and clamping diodes are introduced the voltage oscillation across the rectifier diodes is eliminated and the load range for zero-voltage switching (ZVS) achievement increases. When the clamping diode is conducting, the resonant inductance is shorted and its current keeps constant. So the clamping diode is hard turned-off, leading to reverse recovery loss if the output filter inductance is relatively larger. By introducing a reset winding in series with the resonant inductance to make the clamping diode current decay rapidly when it conducts this paper improves the full-bridge converter. The conduction losses are reduced by the use of reset winding. Also the clamping diodes naturally turn-off and avoids the reverse recovery. The proposed converter has been simulated for two different configurations and results have been compared. A 1 kW prototype converter is built to verify the operation principle and the experimental results are also demonstrated.

KEYWORDS:

1.      Clamping diodes

2.      Full bridge converter

3.      Reset winding

4.      Zero-voltage-switching (ZVS).

SOFTWARE: MATLAB/SIMULINK

CIRCUIT DIAGRAM:

Fig: 1. Tr-Lag type ZVS full bridge PWM full bridge converter

Fig:2  Tr-Lead type ZVS full bridge PWM full bridge converter

EXPECTED SIMULATION RESULTS:

    

Fig:9. Voltage Across Switch Q1 (Tr-Lead)

Fig:10. Current Through Lr (Tr-Lead)

Fig;11:Inverter output Voltage (Tr-Lead)

Fig:12. Rectifier Output Voltage (Tr-Lead)

         

CONCLUSION:

A ZVS PWM full-bridge converter is proposed in this paper, it employs an additional reset winding to make the clamping diode current decay rapidly when the clamping diode conducts, thus the conduction losses of the clamping diodes. The reset winding removes the need of auxiliary switches and the resonant inductance is reduced. The use of reset winding removes the need of hard switching for clamping diodes so there will not be any power loss due to switching of clamping diodes and the conversion efficiency will increased. In the meanwhile, the clamping diodes can be turned off naturally without reverse recovery over the whole input voltage range, and the output filter inductance can be designed to be large to obtain small current ripple, leading to reduced filter capacitance. Compared with the traditional full bridge converter, the proposed circuit provides another simple and effective approach to avoid the reverse recovery of the clamping diodes. The structure and operation of the proposed ZVS PWM full-bridge converter with reset winding topology are described and two configurations have been studied i.e. Transformer leading and Transformer-Lagging connections. We have studied the performance of both the configuration. If we compare the rectifier output in both the case we find that Tr-Lag connection produces less ripples. Transformer lagging configuration is advisable for more accurate results.

REFERENCES:

[1] B.P. Mcgrath, D.G. Holmes, McGoldrick and A.D. Mclve, “Design of a soft-switched 6-kW battery charger for traction applications,” IEEE Trans. Power Electron, vol.22,no. 4, pp. 1136-1144, Jull. 2007.

[2] J. Dudrick, P. Spanik and N.D. Trip, “Zero-voltage and zero-current switching full-bridge dc-dc converter with auxiliary transformer,” IEEE Trans. Power Electron, vol.21, no.5, pp.1328-1335, Sep. 2006.

[3] J.Zhang, X. Xie, X. Wu, G. Wu and Z. Qian, “ A novel zero-current transition full bridge dc-dc converter,” IEEE Trans. Power Electron, vol. 21, no. 2, pp. 354-360, Mar. 2006.

[4] Darlwoo Lee, Taeyoung Abu, Byungcho Choi, “A new soft switching dc-to-dc converter employing two transformer”, . PESC, pp. 1-7, June 2006.

[5] Xinyu Xu Ashwin M. Khambadkhone, Toh Meng Leong, Ramesh Oruganti, “ A 1 MHz zero-voltage switching asymmetrical half bridge dc/dc converter: analysis and design” IEEE Trans. Power Electron, vol.21, no. 1, pp. 105-113, Jan. 2006.

Design and Simulation of Three Phase Inverter for grid connected Photovoltaic systems

ABSTRACT:
Grid connected photovoltaic (PV) systems feed electricity directly to the electrical network operating parallel to the conventional source. This paper deals with design and simulation of a three phase inverter in MATLAB SIMULINK environment which can be a part of photovoltaic grid connected systems. The converter used is a Voltage source inverter (VSI) which is controlled using synchronous d-q reference frame to inject a controlled current into the grid. Phase lock loop (PLL) is used to lock grid frequency and phase. The design of low pass filter used at the inverter output to remove the high frequency ripple is also discussed and the obtained simulation results are presented.

KEYWORDS:
1.      VSI Inverter

2.      PLL

3.      d-q reference frame

4.      Grid connected system.

SOFTWARE: MATLAB/SIMULINK

  

BLOCK DIAGRAM:

  

EXPECTED SIMULATION RESULTS:

CONCLUSION:

The design of the system is carried out for feeding 1KW power to the grid The Inverter is controlled in order to feed active power to the grid, using synchronous d-q transformation. PLL is used to lock grid frequency and phase. The phase detection part of PLL is properly done by using dq transformation in the three phase system. The FFT analysis of the inverter output current shows that the THD is within limits and the controlled injected current generates three phase balance current which controls power at the output of the transformer. To simulate the actual grid connected PV system, the PV model, dc to dc converter model and the control of the dc to dc converter should be included in place of the battery source.

REFERENCES:

[1] Soeren Baekhoej, John K Pedersen & Frede Blaabjerg, ―A Review of single phase grid connected inverter for photovoltaic modules,‖ IEEE transaction on Industry Application , Vol. 41,pp. 55 – 68, Sept 2005

[2] Milan Pradanovic& Timothy Green, ―Control and filter design of three phase inverter for high power quality grid connection, ― IEEE transactions on Power Electronics,Vol.18. pp.1- 8, January 2003

[3] C Y Wang,Zhinhong Ye& G.Sinha, ― Output filter design for a grid connected three phase inverter,‖Power electronics Specialist Conference, pp.779-784,PESE 2003

[4] Samul Araujo& Fernando Luiz, ― LCL fiter design for grid connected NPC inverters in offshore wind turbins,‖ 7th International conference on Power Electronics, pp. 1133-1138, October 2007.

[5] Frede Blaabjerg , Remus Teodorescu and Marco Liserre, ―Overview of control & grid synchronization for distributed power generation systems,‖ IEEE transaction on Industrial Electronics, Vol. 53, pp. 500 – 513,Oct- 2006