Intensive Programme “Renewable Energy Sources”

relatively reliable. Unfortunately, in some cases it can converge to non-physical solutions and increase total number of iterations.

The lowest CPU requirements have been observed in approach No. 5 (+11.8%) when compared to approaches No. 4 and No. 6 with increase of 16.5% and 39.0%, respectively.

5. Conclusions

In this paper, introductory analysis of different stability algorithms for Newton-Raphson method has been performed. Finally, the One-Shot Fast-Decoupled and One-Shot Gauss-Seidel approaches with V updates only in combination with the truncation algorithm have been found the most reliable in terms of convergence to physical solutions, total number of iterations, CPU time and modification level of the original Newton-Raphson code.

However, the R/X modifications and Jacobian adjustments (e.g. Hessian inclusion) have not been considered. Therefore, future research of this problem is intended to find more reliable techniques, which would show better convergence properties also for ill-conditioned load flow cases.

REFERENCES

1. Heckmann, W.; Sorg, A.; Weber, Th.; Wellssow, W.H.: Enhanced AC Power-Flow Solutions for Reliability Analyses. Paper in ETEP, Vol. 11, No. 2, pp. 79-88. March/April 2001

2. Koh, C.S.; Ryu, J.S.; Fujiwara, K.: Convergence Acceleration of the Newton-Raphson Method Using Successive Quadratic Function Approximation of Residual. Paper in IEEE Transactions on magnetics, Vol. 42, No. 4, pp. 611-614. April 2006

3. Lagace, P.J.; Vuong, M.H.; Kamwa, I.: Improving Power Flow Convergence by Newton Raphson with a Levenberg-Marquardt Method. Paper in IEEE Transactions. Montreal: 2008

4. Glover, J.D.; Sarma, M.S.; Overbye, T.J.: Power Systems Analysis and Design – 4^th edition. CENGAGE-Engineering, May 2007.

5. Canizares, C.; Conejo, A.J.; Exposito, A.G.: Electric Energy Systems: Analysis and Operation, CRC Press. New York, July 2008.

6. Bergen, A.R.; Vittal, V.: Power System Analysis – 2^nd edition, Prentice-Hall, 2000.

7. PowerWorld Corporation, PowerWorld Simulator 13 GSO version.

8. http://www.tavanir.org.ir/dm/etozi/download/siemens/Network%20Analysis%20and%20Calc ulation/06-LoadFlow.ppt

9. http://grb.physics.unlv.edu/~zbb/files/upload/29UV3GPCVQWO6ERVE9RABFQ5M.pdf

ACKNOWLEDGEMENT

The author would like to acknowledge Prof. Malcolm Irving of the Brunel Institute of Power Systems, Brunel University, UK for providing data for 61- and 629-bus ill-conditioned power systems.

This research has been supported by Department of Commerce - project no. MPO 2A-2TP1/051 and the students project SGS-2010-018.

Authors:

Ing. Jan Veleba, e-mail: jveleba@kee.zcu.cz

University of West Bohemia

Department of Electrical Power Engineering and Ecology

Univerzitní 8, 306 14 Plzeň, Czech Republic

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