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

 

5

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.