Grid Impedance Estimation Using Several Short-Term Low Power Signal Injections

Document Type : Research Article


1 Image Processing & Data Mining Lab, Shahrood University of Technology, Shahrood, Iran

2 Power Engineering Group, the University of Queensland, Queensland, Australia


In this paper, a signal processing method is proposed to estimate the low and high-frequency impedances of power systems using several short-term low power signal injections for a frequency range of 0-150 kHz. This frequency range is very important, and thusso it is considered in the analysis of power quality issues of smart grids. The impedance estimation is used in many power system applications such as power quality analysis of smart grids and grid connected renewable energy systems. The proposed impedance estimation technique is based on applying a wideband voltage signal at a Point of Common Coupling (PCC) and then a division of the voltage to a generated current signal in a frequency range of 0-150 kHz. In a noisy system, the energy of the injected signal must be sufficient for an accurate approximation. This is the main issue in proposing a new method for the impedance estimation. In this paper, our simulation error is additive white Gaussian noise which is considered as a generic measurement noise. The proposed algorithm consists of three main parts: 1) Determining several injection signals with sufficient energy using the Genetic algorithm. At least one of the determined signals should have sufficient energy in some frequencies so that the union of these ranges is can be the universal set of estimation. 2) Injecting individuals of the signals to the grid separately, and estimating the impedance following Ohm’s law. The width of injection signals is calculated by the best chromosome in GA. 3) The fusion of estimated impedances. The simulation results show that the proposed method can properly estimate grid impedance in a wide frequency range up to 150 kHz.


Main Subjects

[1] M. Ciobotaru, R. Teodorescu, F. Blaabjerg, On-line grid impedance estimation based on harmonic injection for grid-connected PV inverter, in: International Symposium on Industrial Electronics, IEEE, 2007, pp. 2437-2442.
[2] M. Cespedes, J. Sun, Adaptive Control of Grid-Connected Inverters Based on Online Grid Impedance Measurements, IEEE Transactions on Sustainable Energy, 5(2) (2014) 516-523.
[3] J. Das, Passive filters-potentialities and limitations, in: Pulp and Paper Industry Technical Conference, 2003. Conference Record of the 2003 Annual, IEEE, 2003, pp. 187-197.
[4] A. Tarkiainen, R. Pollanen, M. Niemela, J. Pyrhonen, Identification of grid impedance for purposes of voltage feedback active filtering, IEEE Power Electronics Letters, 2(1) (2004) 6-10.
[5] M. Ciobotaru, V.G. Agelidis, R. Teodorescu, F. Blaabjerg, Accurate and less-disturbing active antiislanding method based on PLL for grid-connected converters, IEEE Transactions on Power Electronics, 25(6) (2010) 1576-1584.
[6] L. Asiminoaei, R. Teodorescu, F. Blaabjerg, U. Borup, A digital controlled PV-inverter with grid impedance estimation for ENS detection, IEEE Transactions on Power Electronics, 20(6) (2005) 1480-1490.
[7] Y.L. Familiant, K.A. Corzine, J. Huang, M. Belkhayat, AC Impedance Measurement Techniques, in: IEEE International Conference on Electric Machines and Drives, 2005, pp. 1850-1857.
[8] L.S. Czarnecki, Z. Staroszczyk, Dynamic on-line measurement of equivalent parameters of three-phase systems for harmonic frequencies, European Transactions on Electrical Power, 6(5) (1996) 329-336.
[9] T. Roinila, M. Vilkko, J. Sun, Online Grid Impedance Measurement Using Discrete-Interval Binary Sequence Injection, IEEE Journal of Emerging and Selected Topics in Power Electronics, 2(4) (2014) 985-993.
[10] Z. Shen, M. Jaksic, P. Mattavelli, D. Boroyevich, J. Verhulst, M. Belkhayat, Three-phase AC system impedance measurement unit using chirp signal injection, in: Applied Power Electronics Conference and Exposition (APEC), Twenty-Eighth Annual IEEE, 2013, pp. 2666-2673.
[11] M. Ciobotaru, V. Agelidis, R. Teodorescu, Line impedance estimation using model based identification technique, in: Power Electronics and Applications, Proceedings of the 14th European Conference on, 2011, pp. 1-9.
[12] M.M. AlyanNezhadi, F. Zare, H. Hassanpour, Passive grid impedance estimation using several short-term low power signal injections, in: 2nd International Conference on Signal Processing and Intelligent System, IEEE, Tehran, Iran, 2016.
[13] C. Cano, A. Pittolo, D. Malone, L. Lampe, A.M. Tonello, A.G. Dabak, State of the Art in Power Line Communications: From the Applications to the Medium, IEEE Journal on Selected Areas in Communications, 34(7) (2016) 1935-1952.
[14] S.D. Alessandro, M.D. Piante, A.M. Tonello, On modeling the sporadic impulsive noise rate within in-home power line networks, in: IEEE International Symposium on Power Line Communications and Its Applications (ISPLC), 2015, pp. 154-159.
[15] R. Hashmat, P. Pagani, A. Zeddam, T. Chonavel, MIMO communications for inhome PLC networks: Measurements and results up to 100 MHz, in: Power Line Communications and Its Applications (ISPLC), IEEE International Symposium on, 2010, pp. 120-124.
[16] J.A. Cortes, L. Diez, F.J. Canete, J.J. Sanchez-Martinez, Analysis of the Indoor Broadband Power-Line Noise Scenario, IEEE Transactions on Electromagnetic Compatibility, 52(4) (2010) 849-858.
[17] M. Katayama, T. Yamazato, H. Okada, A mathematical model of noise in narrowband power line communication systems, IEEE Journal on Selected Areas in Communications, 24(7) (2006) 1267-1276.
[18] T. Esmailian, F.R. Kschischang, P. Glenn Gulak, In-building power lines as high-speed communication channels: channel characterization and a test channel ensemble, International Journal of Communication Systems, 16(5) (2003) 381-400.
[19] Y. Jie, Z. Zhixiong, S. Anwen, X. Jinbang, W. Fang, Kalman filter based grid impedance estimating for harmonic order scheduling method of active power filter with output LCL filter, in: International Symposium on Power Electronics, Electrical Drives, Automation and Motion (SPEEDAM), 2016, pp. 359-364.
[20] G. Herong, X. Guo, W. Deyu, W. Wu, Real-time grid impedance estimation technique for grid-connected power converters, in: Industrial Electronics (ISIE), International Symposium on, IEEE, 2012, pp. 1621-1626.
[21] B.L. Eidson, D.L. Geiger, M. Halpin, Equivalent power system impedance estimation using voltage and current measurements, in: Clemson University Power Systems Conference, 2014, pp. 1-6.
[22] S. Cobreces, E.J. Bueno, D. Pizarro, F.J. Rodriguez, F. Huerta, Grid Impedance Monitoring System for Distributed Power Generation Electronic Interfaces, IEEE Transactions on Instrumentation and Measurement, 58(9) (2009) 3112-3121.
[23] T. Roinila, M. Vilkko, J. Sun, Broadband methods for online grid impedance measurement, in: Energy Conversion Congress and Exposition, IEEE, 2013, pp. 3003-3010.
[24] S. Han, D. Kodaira, S. Han, B. Kwon, Y. Hasegawa, H. Aki, An automated impedance estimation method in low-voltage distribution network for coordinated voltage regulation, IEEE Transactions on Smart Grid, 7(2) (2016) 1012-1020.
[25] D. Whitley, N.-W. Yoo, Modeling Simple Genetic Algorithms for Permutation, Foundations of Genetic Algorithms (FOGA 3), 3 (2014) 163.
[26] J. Genlin, Survey on genetic algorithm [J], Computer Applications and Software, 2 (2004) 69-73.