The Coupling of Voltage and Frequecncy Response in Splitting Island and Its Effects on Load-shedding Relays

Hao Yang, Baohui Zhang

School of Electrilcal Engineering, Xi’an Jiaotong University, Xi’an, China.

DOI: 10.4236/epe.2013.54B128                

Abstract

The voltage and frequency dynamics interact with each other in the island after splitting. The current frequency response model without considering the voltage effect would bring remarkable errors when analyzing the frequency dynamic progress in the island with large-capacity active-power shortage. In this paper, coupling effects of voltage and frequency are studied to indicate that initial reactive-power deficit and load characteristics have strong effects on the coupling effects of the voltage and frequency. Moreover, control effects of currently used under frequency load-shedding relays (UFLS) and under voltage load-shedding relays (UVLS) which are installed and executed independently are examined to find that it would sometimes cause excessive or inadequate control without considering the coupling, suggesting that it is necessary to develop coordinate control methods for voltage and frequency problems.

Keywords

Frequency Response; Coupling Effects; Splitting Island; Coordination Control

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	P. Kunder, “Power System Stability and Control,” New York： McGraw-Hill, 1994, EPRI Power System Engineering Series.
[2]	X. G．Zhang, C. G．Li, Y. T. Liu, et al, “Reviews on Power System Dynamic Frequency Analysis and Its Application,” Transactions of China Electrotechnical Society, Vol. 25, No. 21, 2010, pp. 168-176．
[3]	Q. B. Zhao, Z. L. Zhang and J. H. Bai, “Energy Sources Distribution and Power Development Strategy,” Electric Power, Vol. 40, No. 12, 2007, pp. 1-5.
[4]	Q. Zhao, Z. X. Liu and L. Zhang, “Discussions on Several Problems of Under-frequency Load Shedding Scheme in China,” Automation of Electric Power Systems, Vol. 34, No. 11, 2010, pp. 48-53.
[5]	X. Zhou, M. K. Zhou, W. L, et al, “Analysis on Adaptability of UFLS&UVLS Scheme in Jiangsu District Grids,” Jiangsu Electricl Engineering, Vo. 31, No. 2, 2009, pp. 5-7.
[6]	P. M. Anderson and M. Mirheydar, “A Low-order System Frequency Response Model,” IEEE Transactions on Power Systems, Vol. 5, No. 3, 1990, pp. 720-729. doi:10.1109/59.65898
[7]	M. L. Chan, R. D. Dunlop and F. Schweppe, “Dynamic Equivalents for Average System Frequency Behavior Folowwing Major Disturbances, ” IEEE Transactions on Power Apparatus and Systems, Vol. PAS-91, No. 4, 1972, pp. 1637-1642. doi:10.1109/TPAS.1972.293340
[8]	Y. S. Xue, “Space-time Cooperative Framework for Defending Blackouts: PartIII Optimization and Corridenation for Defense Lines,” Automation of Electric Power Systems, Vol. 30, No. 3, 2006, pp. 1-10.
[9]	C. X. Ren, Y. S. Xue, M. Ding, et al., “Negative Control Effects of UFLS and UVLS,” Automation of Electric Power Systems, Vol. 33, No. 10, 2009, pp. 1-5.
[10]	U. Rudez and R. Mihalic, “Analysis of Underfrequency Load Shedding Using a Frequency Gradient,” IEEE Transactions on Power Delivery, Vol. 26, No. 2, 2011, pp. 565-575. doi:10.1109/TPWRD.2009.2036356