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.

Neuro Fuzzy based controller for Power Quality Improvement

International Conference on Computational Intelligence and Communication Networks, 2015

ABSTRACT: Use of power electronic converters with nonlinear loads leads to power quality problems by producing harmonic currents and drawing reactive power. A shunt active power filter provides an elegant solution for reactive power compensation as well as harmonic mitigation leading to improvement in power quality. However, the shunt active power filter with PI type of controller is suitable only for a given load. If the load is varied, the proportional and integral gains are required to be fine tuned for each load setting. The present study deals with hybrid artificial intelligence controller, i.e. neuro fuzzy controller for shunt active power filter. The performance of neuro fuzzy controller over PI controller is examined and tabulated. The salvation of the problem is extensively verified with various loads and plotted the worst case out of them for the sustainability of the neuro fuzzy controller.

 

KEYWORDS:

  1. Active Power Filter
  2. Neuro Fuzzy Controller
  3. Back Propagation Algorithm
  4. Soft Computing

 

SOFTWARE: MATLAB/SIMULINK

 

BLOCK DIAGRAM:

Fig 1. Schematic Diagram of Shunt Active Power Filter

  

EXPECTED SIMULATION RESULTS:

   

Fig 2. (a) Waveform of Load Current, Compensating Current, Source

Current and Source Voltage for Case V of Table1 (1kVA with α=60o) and

(b) Waveform of Source Voltage and in phase Source Current of Fig. (a) Reproduced

 

CONCLUSION:

The application of hybrid artificial intelligence technique on shunt active power filter is proved to be an eminent solution for the mitigation of harmonics and the compensation of reactive power. The hybrid artificial intelligence used here is the neuro fuzzy controller. It takes the linguistic inputs as a fuzzy logic controller and it adapts any situation in between the running of the program as the neural network. The simulation results states that the active power filter controller with neuro fuzzy controllers have been seen to eminently minimize harmonics in the source current when the load demands non sinusoidal current, irrespective of whether the load is fixed or variable when compared to PI Controller. Simultaneously, the power factor at source also becomes the unity, if the load demands reactive power. The neuro fuzzy controller is far superior to the PI controller for all the loads. In the present work, a range of values of the load is considered to robustly test the controllers. It has been demonstrated that neuro fuzzy controller offers more acceptable results over the PI controller. The neuro fuzzy controller, therefore, significantly improves the performance of a shunt active power filter.

 

REFERENCES:

  • Laszlo Gyugyi, “Reactive Power Generation and Control by Thyristor Circuits”, IEEE Transactions on Industry Applications, vol. IA-15, no. 5, September/October 1979.
  • Akagi, Y. Kanazawa, and A. Nabae, “Instantaneous reactive power compensators comprising switching devices without energy storage components,” IEEE Transaction Industrial Applications, vol. IA-20, pp. 625-630, May/June 1984.
  • Z. Peng, H. Akagi, and A. Nabae, “A study of active power filters using quad series voltage source pwm converters for harmonic compensation,” IEEE Transactions on Power Electronics, vol. 5, no. 1, pp. 9–15, January 1990.
  • Conor A. Quinn, Ned Mohan, “Active Filtering of Harmonic Currents in Three-phase, Four-Wire Systems with Three-phase and Single-phase Non-Linear Loads”, IEEE-1992.
  • A. Morgan, J. W. Dixon, and R. R. Wallace, “A three-phase active power filter operating with fixed switching frequency for reactive power and current harmonic compensation,” IEEE Transactions on Industrial Electronics, vol. 42, no. 4, pp. 402–408, August 1995.

PSO – PI Based DC Link Voltage Control Technique for Shunt Hybrid Active Power Filter

2016 IEEE

ABSTRACT: In power systems, the intensive use of nonlinear loads causes several power quality problems such as current harmonic pollution. In order to reduce the current harmonic pollution, the shunt hybrid active filter (SHAPF) is the best solutions effectively. In shunt hybrid active filter systems SHAPFs, the design of dc link controller is a significant and challenging task due to its impact on the performance and stability of the overall system. The main contribution of this paper is that the particle swarm optimization (PSO) algorithm is applied gains for PI controller which can result in the improved response in terms of response time and overshoot. In proposed control method, the performance results of harmonic compensation are satisfactory. Theoretical analyses and simulation results are obtained from an actual industrial network model in PSCAD. The simulation results are presented for proposed system in order to demonstrate that the harmonic compensation performance meets the IEEE-519 standard.

KEYWORDS

  1. DC link controller
  2. Harmonics
  3. Particle swarm optimization
  4. Power quality
  5. PSCAD
  6. Shunt hybrid active power filter

SOFTWARE: MATLAB/SIMULINK

 CIRCUIT DIAGRAM:

Figure 1. SHAPF Power System

 EXPECTED SIMULATION RESULTS

 

Figure 2 Comparison of PI, PID and PSO based PI controller for DC link

Control

Figure 3 Three phase Source Voltages, Load – M-SHAPF – Source

Currents, SHAPF DC link Voltage

Figure 4 Source -Load-M-SHAPF active power, Source -Load-M-SHAPF

reactive power

 CONCLUSION

The intensive use of nonlinear loads causes several power quality problems such as current harmonic pollution. In order to reduce the current harmonic pollution, the shunt hybrid active filter (SHAPF) is the best solution effectively. In shunt hybrid active filter systems (SHAPF)s, the design of dc link controller is a significant and challenging task due to its impact on the performance and stability of the overall system. On account of the limitations between existing literatures, the purpose of this paper is that PSO algorithm has been proposed to adapt the dc link controller gains of the SHAPF. In this paper, the particle swarm optimization (PSO) algorithm is applied gains for PI controller which can result in the improved response in terms of response time and overshoot. In proposed control method, the performance results of harmonic compensation are satisfactory. Theoretical analyses and simulation results are obtained from an actual industrial network model in PSCAD. The simulation results are presented for proposed system in order to demonstrate that the harmonic

REFERENCES

[1] B. Soudan and M. Saad, “An evolutionary dynamic population size PSO implementation,” in Information and Communication Technologies: From Theory to Applications, 2008. ICTTA 2008. 3rd International Conference on, 2008, pp. 1–5.

[2] J. Kennedy, “Particle swarm optimization” IEEE International Conference on Neural Network , pp. 1942 – 1948 , 1995. doi: 10.1109/ICNN.1995.488968.

[3] Chien-Hung Liu and Yuan-Yih Hsu, “Design of a Self-Tuning PI Controller for a STATCOM Using Particle Swarm Optimization,” IEEE Transactions on Industrial Electronics, vol. 57, no. 2, pp. 702– 715, Feb. 2010.

[4] J. Turunen, M. Salo and H. Tuusa, “Comparison of three series hybrid active power filter topologies”, 11th International Conference on. Harmonics and Quality of Power, pp. 324–329, Sept. 2004. doi: 10.1109/ICHQP.2004.1409375.

[5] M. A. Mulla, C. Rajagopalan, A. Chowdhury,”Compensation of three-phase diode rectifier with capacitive filter working under unbalanced supply conditions using series hybrid active power filter”, IET Power Electronics, vol.7, (6), pp. 1566–1577, 2014, doi: 10.1049/iet-pel.2013.0605.

Harmonics Reduction And Power Quality Improvement By Using DPFC

 

ABSTRACT:

The DPFC is derived from the unified power-flow controller (UPFC). The DPFC can be considered as a UPFC with an eliminated common dc link. The active power exchange between the shunt and series converters which is through the common dc link in the UPFC is now through the transmission lines at the third-harmonic frequency. The DPFC employs the distributed concept, in which the common dc-link between the shunt and series converters are eliminated and three-phase series converter is divided to several single-phase series distributed converters through the line. According to the growth of electricity demand and the increased number of non-linear loads in power grids harmonics, voltage sag and swell are the major power quality problems. DPFC is used to mitigate the voltage deviation and improve power quality. Simulations are carried out in MATLAB/Simulink environment. The presented simulation results validate the DPFC ability to improve the power quality.

KEYWORDS:

  1. Load flow control
  2. FACTS
  3. Power Quality
  4. Harmonics
  5. Sag and Swell Mitigation
  6. Distributed Power Flow Controller
  7. Y–Δ transformer

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. DPFC configuration

EXPECTED SIMULATION RESULTS:

 

Fig 2. three phase voltage sag waveform without DPFC

 

Fig. 3 three phase voltage sag waveform with DPFC

 Fig.4 3-ϕ load current swell waveform without DPFC

Fig.5 Mitigation of 3-ϕ load current swell with DPFC

             

Fig.6 Total harmonic distortion of load voltage without DPFC

.Fig.7 Total harmonic distortion of load voltage with DPFC

 CONCLUSION:

This paper has presented a new concept called DPFC. The DPFC emerges from the UPFC and inherits the control capability of the UPFC, which is the simultaneous adjustment of the line impedance, the transmission angle, and the bus voltage magnitude. The common dc link between the shunt and series converters, which is used for exchanging active power in the UPFC, is eliminated. This power is now transmitted through the transmission line at the third-harmonic frequency. The series converter of the DPFC employs the DFACTS concept, which uses multiple small single-phase converters instead of one large-size converter. The reliability of the DPFC is greatly increased because of the redundancy of the series converters. The total cost of the DPFC is also much lower than the UPFC, because no high-voltage isolation is required at the series-converter part and the rating of the components of is low. To improve power quality in the power transmission system, the harmonics due to nonlinear loads, voltage sag and swell are mitigated. To simulate the dynamic performance, a three-phase fault is considered near the load. It is shown that the DPFC gives an acceptable performance in power quality improvement and power flow control.

 REFERENCES:

[1] S.Masoud Barakati Arash Khoshkbar sadigh and Mokhtarpour.Voltage Sag and Swell Compensation with DVR Based on Asymmetrical Cascade Multicell Converter North American Power Symposium (NAPS),pp.1-7,2011.

[2] Zhihui Yuan, Sjoerd W.H de Haan, Braham Frreira and Dalibor Cevoric “A FACTS Device: Distributed Power Flow Controller (DPFC)” IEEE Transaction on Power Electronics, vol.25, no.10, October 2010.

[3] Zhihui Yuan, Sjoerd W.H de Haan and Braham Frreira “DPFC control during shunt converter failure” IEEE Transaction on Power Electronics 2009.

[4] M. D. Deepak, E. B. William, S. S. Robert, K. Bill, W. G. Randal, T. B. Dale, R. I. Michael, and S. G. Ian, “A distributed static series compensator system for realizing active power flow control on existing power lines,” IEEE Trans. Power Del., vol. 22, no. 1, pp. 642–649, Jan. 2007.

[5] D. Divan and H. Johal, “Distributed facts—A new concept for realizing grid power flow control,” in Proc. IEEE 36th Power Electron. Spec. Conf. (PESC), 2005, pp. 8–14.

Harmonics Reduction And Power Quality Improvement By Using DPFC

 

ABSTRACT:

The DPFC is derived from the unified power-flow controller (UPFC). The DPFC can be considered as a UPFC with an eliminated common dc link. The active power exchange between the shunt and series converters which is through the common dc link in the UPFC is now through the transmission lines at the third-harmonic frequency. The DPFC employs the distributed concept, in which the common dc-link between the shunt and series converters are eliminated and three-phase series converter is divided to several single-phase series distributed converters through the line. According to the growth of electricity demand and the increased number of non-linear loads in power grids harmonics, voltage sag and swell are the major power quality problems. DPFC is used to mitigate the voltage deviation and improve power quality. Simulations are carried out in MATLAB/Simulink environment. The presented simulation results validate the DPFC ability to improve the power quality.

KEYWORDS:

  1. Load flow control
  2. FACTS
  3. Power Quality
  4. Harmonics
  5. Sag and Swell Mitigation
  6. Distributed Power Flow Controller
  7. Y–Δ transformer

SOFTWARE: MATLAB/SIMULINK

BLOCK DIAGRAM:

Fig. 1. DPFC configuration

EXPECTED SIMULATION RESULTS:

 

Fig 2. three phase voltage sag waveform without DPFC

 

Fig. 3 three phase voltage sag waveform with DPFC

Fig.4 3-ϕ load current swell waveform without DPFC

Fig.5 Mitigation of 3-ϕ load current swell with DPFC

             

Fig.6 Total harmonic distortion of load voltage without DPFC

Fig.7 Total harmonic distortion of load voltage with DPFC

 CONCLUSION:

This paper has presented a new concept called DPFC. The DPFC emerges from the UPFC and inherits the control capability of the UPFC, which is the simultaneous adjustment of the line impedance, the transmission angle, and the bus voltage magnitude. The common dc link between the shunt and series converters, which is used for exchanging active power in the UPFC, is eliminated. This power is now transmitted through the transmission line at the third-harmonic frequency. The series converter of the DPFC employs the DFACTS concept, which uses multiple small single-phase converters instead of one large-size converter. The reliability of the DPFC is greatly increased because of the redundancy of the series converters. The total cost of the DPFC is also much lower than the UPFC, because no high-voltage isolation is required at the series-converter part and the rating of the components of is low. To improve power quality in the power transmission system, the harmonics due to nonlinear loads, voltage sag and swell are mitigated. To simulate the dynamic performance, a three-phase fault is considered near the load. It is shown that the DPFC gives an acceptable performance in power quality improvement and power flow control.

 

REFERENCES:

[1] S.Masoud Barakati Arash Khoshkbar sadigh and Mokhtarpour.Voltage Sag and Swell Compensation with DVR Based on Asymmetrical Cascade Multicell Converter North American Power Symposium (NAPS),pp.1-7,2011.

[2] Zhihui Yuan, Sjoerd W.H de Haan, Braham Frreira and Dalibor Cevoric “A FACTS Device: Distributed Power Flow Controller (DPFC)” IEEE Transaction on Power Electronics, vol.25, no.10, October 2010.

[3] Zhihui Yuan, Sjoerd W.H de Haan and Braham Frreira “DPFC control during shunt converter failure” IEEE Transaction on Power Electronics 2009.

[4] M. D. Deepak, E. B. William, S. S. Robert, K. Bill, W. G. Randal, T. B. Dale, R. I. Michael, and S. G. Ian, “A distributed static series compensator system for realizing active power flow control on existing power lines,” IEEE Trans. Power Del., vol. 22, no. 1, pp. 642–649, Jan. 2007.

[5] D. Divan and H. Johal, “Distributed facts—A new concept for realizing grid power flow control,” in Proc. IEEE 36th Power Electron. Spec. Conf. (PESC), 2005, pp. 8–14.

Implementation of Adaptive Filter in Distribution Static Compensator

 

ABSTRACT:

This paper presents an implementation of an adaptive filter in a three-phase distribution static compensator (DSTATCOM) used for compensation of linear/nonlinear loads in a three-phase distorted voltage ac mains. The proposed filter, which is based on adaptive synchronous extraction, is used for extraction of fundamental active- and reactive-power components of load currents in estimating the reference supply currents. This control algorithm is implemented on a developed DSTATCOM for reactive-power compensation, harmonics elimination, load balancing, and voltage regulation under linear and nonlinear loads. The performance of DSTATCOM is observed satisfactory under unbalanced time-varying loads.

KEYWORDS

  1. Adaptive filter (AF)
  2. distribution static compensator (DSTATCOM)
  3. harmonics
  4. load balancing
  5. sinusoidal tracking algorithm
  6. voltage-source converter (VSC)

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig.1. Schematic of three-leg DSTATCOM.

EXPECTED SIMULATION RESULTS:

(a)

(b)

                                                             (c)

Fig. 2. (a), (b), and (c) Various intermediate signals of the control algorithm at load injection. (a) Ch. 1 and 2: 200 V/div; Ch. 3 and 4: 20 A/div; Time axis: 50 ms/div. (b) Ch. 1, 2, 3, and 4: 20 A/div; Time axis: 20 ms/div. (c) Ch. 1, 2,3, and 4: 20 A/div; Time axis: 20 ms/div.

 Fig. 3. Steady-state performance of DSTATCOM at linear lagging PF load in PFC mode. (a) Ps. (b) PL. (c) Pc. (d) vab, isa. (e) vbc, isb. (f) vca, isc.

Fig. 4. Steady-state performance of DSTATCOM at nonlinear loads in PFC mode. (a) vab, isa. (b) vbc, isb. (c) vca, isc. (d) Harmonic spectrum of isa. (e) vab, iLa. (f) Harmonic spectrum of iLa.

Fig. 5. Dynamic performance of DSTATCOM at unbalanced linear loads. (a) vab, isa, isb, isc. (b) vab, iLa, iLb, iLc. (c) vdc, isa, iCa, iLa.

Fig. 6. Dynamic performance of DSTATCOM at unbalanced nonlinear loads. (a) vab, isa, isb, isc. (b) vab, iLa, iLb, iLc. (c) vdc, isa, iCa, iLa

Fig. 7. Steady-state performance of DSTATCOM at linear lagging PF load in ZVR mode. (a) Ps. (b) PL. (c) Pc. (d) vab, isa. (e) vbc, isb. (f) vca, isc.

Fig. 8. Steady-state performance of DSTATCOM at nonlinear load in ZVR mode. (a) vab, isa. (b) vbc, isb. (c) vca, isc. (d) Harmonic spectrum of isa. (e) Harmonic spectrum of iLa. (f) iCa. (g) Ps. (h) PL.

Fig. 9. Variation of Vt, isa, and iLa with vdc under unbalanced linear loads.

 CONCLUSION:

 A DSTATCOM has been implemented for a three-phase distribution system. An AF has been used for control of DSTATCOM. This AF has been found simple and easy to implement, and its performance has been observed satisfactory with nonsinusoidal and distorted voltages of ac mains under load variation. The performance of DSTATCOM with its AF has been demonstrated for harmonics elimination, reactivepower compensation, and load balancing with self-supporting dc link in PFC and ZVR modes. The dc-link voltage of the DSTATCOM has been also regulated to a desired value under time-varying load conditions.

 REFERENCES:

 [1] E. F. Fuchs and M. A. S. Mausoum, Power Quality in Power Systems and Electrical Machines. London, U.K.: Elsevier, 2008.

[2] H. Akagi, E. H. Watanabe, and M. Aredes, Instantaneous Power Theory and Applications to Power Conditioning. Hoboken, NJ, USA: Wiley, 2007.

[3] A. Emadi, A. Nasiri, and S. B. Bekiarov, Uninterruptible Power Supplies and Active Filters. Boca Raton, FL, USA: CRC Press, 2005.

[4] J. Jacobs, D. Detjen, C. U. Karipidis, and R. W. De Doncker, “Rapid prototyping tools for power electronic systems: Demonstration with shunt active power filters,” IEEE Trans. Power Electron., vol. 19, no. 2, pp. 500– 507, Mar. 2004.

[5] A. Ghosh and G. Ledwich, Power Quality Enhancement Using Custom Power Devices. New Delhi, India: Springer Int. Edition, 2009.

Diode Clamped Three Level Inverter Using Sinusoidal PWM

 

ABSTRACT:

An inverter is a circuit which converts dc power into ac power at desired output voltage and frequency. The ac output voltage can be fixed at a fixed or variable frequency. This conversion can be achieved by controlled turn ON & turn OFF or by forced commutated thyristors depending on applications. The output voltage waveform of a practical inverter is non sinusoidal but for high power applications low distorted sinusoidal waveforms are required. The filtering of harmonics is not feasible when the output voltage frequency varies over a wide range. There is need for alternatives. Three level Neutral Point Clamped inverter is a step towards it.

KEYWORDS:

  1. Harmonics
  2. Inverter
  3. THD
  4. PWM

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Figure1.Diode clamped three level inverter

EXPECTED SIMULATION RESULTS:

 

 Figure2. Upper triangular pulse width modulation

Figure3. lower triangular pulse width modulation

Figure4. three level voltage waveform

Figure5.Matlab model of three level inverter feeding induction motor

 Figure 6. stator waveform of three level inverter

 CONCLUSION:

In normal inverters odd harmonics are present which causes distortion of the output waveform. By using the “THREE LEVEL DIODECLAMPED INVERTER” we can eliminate some number of harmonics hence increasing the efficiency of the inverter.

 REFERENCES:

[1] A.Mwinyiwiwa, Zbigneiw Wolanski, ‘Microprocessor Implemented SPWM for Multiconverters with Phase-Shifted Triangle Carriers’ IEEE Trans. On Ind. Appl., Vol. 34, no. 3, pp 1542-1549, 1998.

[2] J. Rodriguez, J.S. Lai, F. Z. Peng, ’ Multilevel Inverters: A Survey of Topologies, Controls and Applications’, IEEE Trans. On Ind. Electronics, VOL. 49, NO. 4, pp. 724-738, AUGUST 2002

[3] D. Soto, T. C. Green, ‘A Comparison of High Power Converter Topologies for the Implementation of FACTS Controller’, IEEE Trans. On Ind. Electronics, VOL. 49, NO. 5, pp. 1072-1080, OCTOBER 2002.

[4] Muhammad H. Rashid, Power Electronics: Circuits, Devices and Applications, Third edition, Prentice Hall of India, New Delhi, 2004.

[5] Dr. P. S. Bimbhra, Power Electronics, Khanna Publishers, Third Edition, Hindustan Offset Press, New Delhi-28, 2004.

Modeling and Control of Hybrid Power Filter using p-q Theory

 

 ABSTRACT:

 The paper presents design of hybrid active power filter (HAPF) in a three-phase three-wire power system. Design is implemented with instantaneous reactive power theory for control of HAPF in order to mitigate harmonics generated by both non-linear and unbalanced load at the point of common coupling (peC). The p-q Theory enables the source current to be decomposed in αβ0 frame to obtain compensation current for each phase. The hysteresis band current controller is used to generate gating pulses for voltage source inverter (VSI). Over all harmonic reduction is achieved via the proposed control of HAPF and the THD levels are per the IEEE-519 standard. Investigation of proposed scheme is validated by extensive simulations using MATLAB / Simulink Sim-Power System tool box.

 KEYWORDS:

  1. Harmonics
  2. Passive Filter
  3. Active Filter
  4. Hybrid Filter
  5. Power Quality

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig. 1: Basic Diagram of SAF

EXPECTED SIMULATION RESULTS:

Fig. 2: Source Current THD (29.9%) without Filter

Fig. 3: Source Current THD (10. I 5%) using Passive Filter

Fig. 4: Source Current THD (4.47%) using Active Filter

Fig. 5: Source Current THD (2.02%) using HAPF

Fig. 6: Compensating Current for Phase a,b and c

Fig. 7: Load Current THD (10.39%) in HAPF

CONCLUSION

This paper highlights the efficacy of HAPF for improving the power quality by eliminating harmonics from power system. The HAPF with a constant power compensation control strategy and hysteresis-band current controller is proposed. A thorough simulation based investigation validates the competency of HAPF among all filters for harmonic mitigation in power system due to current quality problem. The performance examined has demonstrated the efficiency by reducing the source current THD for non-linear load. The THD is well below the specified limit ofIEEE-519 standard.

REFERENCES

[1] A. Baitha and N. Gupta, ” A comparative analysis of passive filters for power quality improvement”, Int. Conf on Advancements in Power and Energy (TAP Energy), pp. 327-332, 20 IS .

[2] B. Singh and V. Verma, “An improved hybrid filter for compensation of current and voltage harmonics for varying rectifier loads”. Int. J. Electrical Power & Energy Systems, Vol. 29, No. 4, pp. 312-xxx, May 2007.

[3] H. Fujita, T. Yamasaki, and H. Akagi, ” A hybrid active filters for damping of harmonic resonance in industrial power system,” IEEE Trans. on Power Electrics, Vol IS , No. 2, pp. 209-216, 2000.

[4] F.Z. Peng, H. Akagi, and A. Nanbe, ” A new approach to harmonic compensation in power systems-A combined system of shunt passive and series active filters,” I EEE Trans. on Ind. Appt, Vol. 26, pp. 983-990, Nov. 1990

[5] B. Singh and V. Verma, “Design and Implementation of a Current Controlled Parallel Hybrid Power Filter” Int. Conf on Power Electronics, Drives and Energy Systems, PEDES’06, pp. 1-7, 2006.

A Two-Level 24-Pulse Voltage Source Converter with Fundamental Frequency Switching for HVDC System

 ABSTRACT

This paper deals with the performance analysis of a two-level, 24-pulse Voltage Source Converters (VSCs) for High Voltage DC (HVDC) system for power quality improvement. A two level VSC is used to realize a 24-pulse converter with minimum switching loss by operating it at fundamental frequency switching (FFS). The performance of this converter is studied on various issues such as steady state operation, dynamic behavior, reactive power compensation, power factor correction, and harmonics distortion. Simulation results are presented for a two level 24-pulse converter to demonstrate its capability.

 

KEYWORDS

  1. Two-Level Voltage Source Converter
  2. HVDC
  3. Multipulse
  4. Fundamental Frequency Switching
  5. Harmonics

 

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 1

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

EXPECTED SIMULATION RESULTS

 2

Fig. 2 Synthesis of Stepped AC voltage waveform of 24-pulse VSC.

 

3

Fig. 3 Steady state performance of proposed 24-pulse voltage source Converter

4

Fig. 4 Dynamic performance of proposed 24-pulse voltage source converter

 

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Fig. 5 Waveforms and harmonic spectra of 24-pulse covnerter i) supply voltage ii) supply current (iii) converter voltage

CONCLUSION

A two level, 24-pulse voltage source converter has been designed and its performance has been validated for HVDC system to improve the power quality with fundamental frequency switching. Four identical transformers have been used for phase shift and to realize a 24-pulse converter along with control scheme using a two level voltage source converter topology. The steady state and dynamic performance of the designed converter configuration has been demonstrated the quite satisfactory operation and found suitable for HVDC system. The characteristic harmonics of the converter system has also improved by the proposed converter configuration with minimum switching losses without using extra filtering requirements compared to the conventional 12-pulse thyristor converter.

 REFERENCES

[1] J. Arrillaga, “High Voltage Direct Current Transmission,” 2nd Edition, IEE Power and Energy Series29, London, UK-1998.

[2] J. Arrilaga and M. Villablanca, “24-pulse HVDC conversion,” IEE Proceedings Part-C, vol. 138, no. 1, pp. 57–64, Jan. 1991..

[3] Lars Weimers, “HVDC Light: a New Technology for a better Environment,” IEEE Power Engineering Review, vol.18, no. 8, pp. 1920-1926, 1989.

[4] Vijay K. Sood, “HVDC and FACTS Controller, Applications of Static Converters in Power Systems”, Kluwar Academic Publishers, The Netherlands, 2004.

[5] Gunnar Asplund Kjell Eriksson and kjell Svensson, “DC Transmission based on Voltage Source Converters, in Proc. of CIGRE SC14 Colloquium in South Africa 1997.