Compensation Of Voltage Sag And Harmonics By Dynamic Voltage Restorer Without Zero Sequence Blocking

 ABSTRACT:

amic Voltage Restorer (DVR) is a power electronic device to protect sensitive loads from voltage sag. Commonly, sensitive loads are electronic-based devices which generate harmonics. This paper presents fuzzy polar based DVR as voltage sag restorer and harmonics compensator without zero sequence blocking. Research presented in this paper uses d-q-0 axis method considering of the value of neutral axis, because the method works very well if the neutral axis value is zero. Result shows that this method can compensate voltage sag with a compensation error of 0.99%. Using this method, DVR may reduce voltage THD from 10.22% to 0.66%.

KEYWORDS:

1.      DVR

2.      Voltage sag

3.      Harmonics

SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

Fig.1 Dynamic voltage restorer

EXPECTED SIMULATION RESULTS:

Fig. 2 Distorted voltages at bus C

Fig. 3 Voltage at bus C after DVR

Fig.4 70% sag at bus C caused by phase-phase-ground fault

Fig.5 70% sag at bus C (caused by phase-phase- ground fault) restored by DVR

 CONCLUSION:

The simulation of a DVR using MATLAB has been presented. Simulation results show that DVR can restore both the voltage sag and voltage harmonics. The efficiency and effectiveness in voltage sag restoration and voltage harmonics compensation showed by the DVR makes it an interesting power quality device compared to other custom power devices. Under normal condition, DVR is able to decrease voltage THD from 10.22 % to 0.66%. And using the proposed method, DVR can restore asymmetrical voltage sag without zero blocking transformer. The average error of DVR voltage sag compensation is 0.99.

REFERENCES:

[1] Hiyama, T., 1994, “Robustness of Fuzzy Logic Power System Stabilizers Applied to Multimachine Power Systems”, IEEE Trans. on Energy Conversion, Vol. 9, No.3, pp.451-45.

[2] Fransisco Jurado, manuel Valverde, May 2003, “Voltage Correction By Dynamic Voltage Restorer Based on Fuzzy Logic Controller”, IEEE Transaction on Industrial Electronics.

[3] Margo P. M. Hery P. M. Ashari, Imanda, 2005, “ Dynamic Voltage Restorer Using Y connected Boost Transformer Controlled by Back propagation Neural Network”, SMELDA, Malang.

[4] Margo P.M. Hery P.M. Ashar,, T. Hiyama, September 2007, “Balanced voltage sag correction using DVR based on Fully polar controller”, ICICIC 2007 Conference Proceedings, Kumamoto Japan.

[5] C. Meyer, R. W. De Doncker, Y. W. Li, and F. Blaabjerg, “Optimized control strategy for a medium-voltage DVR—Theoretical investigations and experimental results”, IEEE Trans. Power Electron., vol. 23, no. 6, pp. 2746–2754, Nov. 2008.