An Integral Method to Improve PLL Performance under Unbalanced Electric Grid Conditions

Abstract:

Accurate phase information on three-phase grid voltage and currents which are supplied by PLL are needed in power system operation. Conventional three-phase synchronous reference frame-based phase locked loop is generally sufficient during balanced operation conditions. But unbalanced in input signal set causes a double-frequency ripple. The output signal is not ideal. There are lots of improved SRF-PLL methods, aiming at removing the double-frequency ripple such as DSC-PLL,MAF-PLL, but these methods may causes a certain time delay. DIF-PLL method is based on adding another signal, which has reverse polarity ripple. It may amplify the harmonic signal. In this paper, an INT-PLL method based on integral is proposed, which wont amplify the harmonics. The comparison of these methods and simulation results are given in this paper.

• Periodical: Applied Mechanics and Materials (Volumes 347-350)
• Pages: 1318-1322
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.347-350.1318
• Online since: August 2013
• Authors: Shu Jun Yao, Ming Ran Bao, Ya Nan Hu, Min Xiao Han, Jun Xian Hou, Lei Wan
• Keywords: PLL, Unbalanced Electric Grid Conditions

References

[1] V. Kaura and V. Blasko, Operation of a phase locked loop system under distorted utility conditions, in IEEE Transactions on Industry Applications, Volume 33, Issue 1, Jan. -Feb. 1997 pp.58-63.

DOI: 10.1109/28.567077

[2] P. Rodriguez, J. Pou, J. Bergas, J.I. Candela, R.P. Burgos and D. Boroyevich, Decoupled Double Synchronous Reference Frame PLL for Power Converters Control, in IEEE Transactions on Power Electronics Volume 22, Issue 2, March 2007 pp.584-592.

DOI: 10.1109/tpel.2006.890000

[3] M.E. Meral, Improved phase-locked loop for robust and fast tracking of three phases under unbalanced electric grid conditions, in Generation, Transmission & Distribution, IET, Volume 6, Issue 2, February. 2012 pp.152-160.

DOI: 10.1049/iet-gtd.2011.0189

[4] Yazdani, D., Bakhshai, A., Joos, G., Mojiri, M.: A nonlinear adaptive synchronization technique for grid-connected distributed energy sources, IEEE Trans. Power Electron., 2008, 23, p.2181–2186.

DOI: 10.1109/tpel.2008.926045

[5] Liccardo, F., Marino, P., Raimond, G.: Robust and fast three-phase PLL tracking system, IEEE Trans. Ind. Electron., 2011, 58, (1), p.221–231.

DOI: 10.1109/tie.2010.2044735

[6] Awad, H., Svensson, J., Bollen, M.J.: Tuning software phase-locked loop for series-connected converters, IEEE Trans. Power Deliv., 2005, 20, p.300–308.

DOI: 10.1109/tpwrd.2004.837823

[7] J. -W. Choi, Y. -K. Kim, and H. -G. Kim, Digital PLL control for single-phase photovoltaic system, IEE Proc. -Electr. Power Appl., vol. 153, no. 1, p.40–46, Jan. (2006).

DOI: 10.1049/ip-epa:20045225

[8] S. Shinnaka, A robust single-phase PLL system with stable and fast tracking, IEEE Transactions on Indus-try Applications, vol. 44, no. 2, Mar-Apr. (2008).

DOI: 10.1109/tia.2008.916750

[9] X. Fang,Y. Wang, M. Li, K. Wang and W. Lei, A Novel PLL Grid Synchronization of Power Electronic Converters in Unbalanced and Variable-Frequency Environment, IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG), pp.466-471, (2010).

DOI: 10.1109/pedg.2010.5545832