Document Type : Article

**Authors**

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

**Abstract**

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.

**Keywords**

**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

(1992).

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

(1997).

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

identication 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

(2011).

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

(2013).

Volume 25, Issue 6

Transactions on Computer Science & Engineering and Electrical Engineering (D)

November and December 2018Pages 3559-3568