Power System Thévenin Equivalent Estimation Based on Phasor Measurements

Document Type : Article


Faculty of Electrical and Computer Engineering, Shahid Beheshti University (SBU), Tehran, Iran


This paper presents a novel algorithm based on phasor measurements to online estimation of power system Thévenin Equivalent (TE) from a generator terminal. Three consecutive phasor measurements of generator terminal voltage and current are used to estimate the system TE. In a real network, system frequency deviation from its nominal value will produce some phase drift in consecutive phasors reported by Phasor Measurements Units (PMUs). To correct the phase drift and synchronizing the reported phasors to the same reference, an improved triangulation method is developed. The improved method uses a virtual vector in its structure. Using this vector alleviates the negative impacts of improper data resulting from noise or disturbances which make the simple triangulation method to be useless. The algorithm is tested on standard NE-39 network and is implemented in Shahid Beheshti University (SBU) protection laboratory to verify the results in a practical area. The obtained results show that the new method can efficiently estimate the  in online mode in steady-state and transient conditions.


Main Subjects

1. Alinezhad, B., Akbari, M., and Kazemi, H. \PMUbased
distribution network load modelling using harmony
search algorithm", 17th Conf. on Electrical
Power Distribution Networks (EPDC), Tehran, Iran,
pp. 1-6 (2012).
2. Safdarian, A., Aminifar, F., Fotuhi-Firuzabad, M., and
Shahidehpour, M. \A Multi-Objective Framework for
Enhancing the Reliability and Minimizing the Cost
of PMU Deployment in Power Systems", Scientia
Iranica, 23(6), pp. 2917-2927 (2016).
3. Soni, S., Bhil, S., and Mehta, D. \Linear state estimation
model using phasor measurement unit (PMU)
technology", 9th Int. Conf. on Elect. Engin., Computing
Science and Automatic Control (CCE), Mexico,
pp. 1-6 (2012).
4. Chebbo, A., Irving, M.R., and Sterling, M.J.H. \Voltage
collapse proximity indicator, behavior and implications",
IEE Gen. Trans. and Dist., 139(3), pp. 241-252
5. Elkateb, M., Abdelkader, M.S., and Kandil, M.S.
\Linear indicator for voltage collapse in power systems",
IEE Gen. Trans. and Dist., 144(2), pp. 139-146
6. Abdelkader, M.S. and Flynn, D. \Graphical determination
of network limits for wind power integration",
IET Gen. Trans. Dist., 3(9), pp. 841-849 (2009).
7. Abdelkader, M.S. and Fox, B. \Voltage stability assessment
for system with large wind power generation",
44th Int. Universities Power Engineering Conf., Glasgow,
United Kingdom, pp. 1-6 (2009).
8. Al-Mohammed, A.H. and Abido, M.A. \A fully adaptive
PMU-based fault location algorithm for seriescompensated
lines", IEEE Trans. on Power Syst.,
29(5), pp. 2129-2137 (2014).
9. Fusco, G. and Russo, M. \Adaptive voltage regulator
design for synchronous generator", IEEE Trans. on
Energy Conv., 23(3), pp. 946-956 (2008).
10. Corsi, S. and Taranto, G. \A real time voltage instability
identi cation algorithm based on local phasor
measurements", IEEE Trans. on Power Syst., 23(3),
pp. 1271-1279 (2008).
11. Smon, I., Verbic, G., and Gubina, F. \Local voltage
stability index using Tellegen's theorem", IEEE Trans.
on Power Syst., 21(3), pp. 1267-1275 (2006).
12. Munan, W., Baozhu, L., and Zhelin, D. \An improved
recursive assessment method of Thevenin equivalent
parameters based on PMU measurement", Power Eng.
and Auto. Conf. (PEAM), Wuhan, China, pp. 372-375
13. Abdelkader, M.S. \Online Thevenin's equivalent using
local PMU measurements", Int. Conf. on Renewable
Energy and Power Quality (ICREPQ 11), Las Palmas,
Spain, pp. 1-4 (2010).
14. Abdelkader, M.S. and Morrow, D. \Online tracking
of Thevenin equivalent parameters using PMU measurements",
IEEE Trans. on Power Syst., 27(2), pp.
975-983 (2012).
15. Tsai, S. andWong, K. \On-line estimation of Thevenin
equivalent with varying system states", IEEE Power
and Energy Society General Meeting-Conv. and Delivery
of Elect. Energy in the 21st Century, Pittsburgh,
USA, pp. 1-7 (2008).
16. Corsi, S. and Taranto, G.N. \Voltage instability alarm
by real-time predictive indicators", IEEE Power and
Energy Society General Meeting, pp. 1-10 (2012)
17. Alinezhad, B. and Karegar, H.K. \On-line Thevenin
impedance estimation based on PMU data and phase
drift correction", IEEE Trans. on Smart Grid, to be
published (2016).
18. Abdelkader, S.M. and Morrow, D.J. \Online Thevenin
equivalent determination considering system side
changes and measurement errors", IEEE Trans. on
Power Syst., 30(5), pp. 2716-2725 (2015)
19. Vanouni, M. \Discussion of \Online Tracking of
Thevenin Equivalent Parameters Using PMU Measurements",
IEEE Trans. on Power Syst., 28(2), p. 1899