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AIF FORUM Jun Yin

Anti-Islanding Techniques for Distributed Power Generators. AIF FORUM Jun Yin. Outline . Introduction Review of Anti-Islanding Techniques Islanding Frequency Model & Hidden Gene Principle Proportional Power Spectral Density (PPSD) for Islanding Detection

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AIF FORUM Jun Yin

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  1. Anti-Islanding Techniquesfor Distributed Power Generators AIF FORUM Jun Yin

  2. Outline • Introduction • Review of Anti-Islanding Techniques • Islanding Frequency Model & Hidden Gene Principle • Proportional Power Spectral Density (PPSD) for Islanding Detection • Covariance Index for Islanding Detection • Adaptive Logic Phase Shift (ALPS) and Adaptive Reactive Power Shift (ARPS) Anti-Islanding Algorithm • Hybrid Anti-Islanding Techniques • Conclusion • Questions • References

  3. Introduction Distributed Generation Systems • DG Systems Regional Dispatch Energy Value Information Distribution Substation Transmission Line Smart Controller Communication & Control Links ~ ~ Genset Wind Photovoltaic Micro gas Central Generating Station Distribution Line Town Remote Load Factory

  4. Unintentional islanding is a situation in which local DG systems continue to supply power to the local loads at a sustained voltage and frequency while the main EPS is de-energized unknowingly. • Islanding operation could be fatally harmful to the line workers and power system facilities. • IEEE Std 1547™-2003 and IEEE Std 929-2000 require that islanded DG systems be shut down within a specified time. • Interconnection of Distributed Power Generators with Power System Fig. 1 Interconnection of DG systems with the power system

  5. Review of Anti-Islanding Techniques • Two types of techniques for anti-islanding purpose • Remote techniques: normally used on the utility site. Most of them are based on the communication between utilities and DG units • Power Line Carrier Communication (PLCC) • Supervisory Control and Data Acquisition Network (SCADA) • Local techniques: used on the DG site. They are based on the information available on the DG site. Two types of local techniques • Passive techniques: Detect abnormalities related to the islanding conditions • Traditional Over/Under Voltage and Over/Under Frequency Protection (OVP/UVP & OFP/UFP) • Rate of Change of Power Output (ROCOP) as an index of islanding • Rate of Change of Frequency (ROCOF) as an index of islanding • Rate of Change of Frequency over Power Change (ROCOFOP) as an index of islanding

  6. Phase Jump Detection (PJD) • Voltage Harmonics Detection (HD) • Active Techniques: introduce disturbance to the DG output for the islanding detection • The Reactive Power Export Error Detection (RPEED) • Impedance Measurement (IM) • Phase Shift (or Frequency Shift) techniques for inverter-based DG systems • Active Frequency Drift (AFD) • Active Frequency Drift with Positive Feedback (AFDPF) • Slip-Mode Frequency Shift (SMS) • Automatic Phase Shift (APS)

  7. General Comparison of Anti-islanding Techniques • Remote Techniques: • Usually do not have non-detection zone (NDZ) • Do not degrade the quality of the generating power of the DG • Effective in multi-DG systems But • too expensive to implement • Complicated communication techniques in multi-DG systems • Local Techniques: • Passive Techniques: • Do not degrade the quality of the power generation of the DG • Inexpensive and easy to implement But • Have relatively large non-detection zone (NDZ) • Effectiveness may be impaired in multi-DG systems • Active Techniques • Relatively small non-detection zone (NDZ) • Inexpensive and easy to implement But • may degrade the quality of the output power and the stability of the DG

  8. Islanding Frequency Model & Hidden Gene Principle • General Aspects of Islanding Operation α < 0 α > 0 Fig. 2 The phase characteristics of the islanding load The relationship between the current period and the voltage period in islanding operation (1)

  9. Hidden Gene Principle & Islanding • A 4th order moving average filter is embedded as a hidden gene into the inverter’s frequency controller • The islanding frequency model Fig. 3 Islanding frequency model • It has been proven that the stable region for islanding operation is (2)

  10. The Frequency Response of The System Fig. 4 System model for response to disturbance and noise Fig. 5 Bode plot of system transfer function

  11. Fig. 6 Frequency response to disturbance and noise

  12. Proportional Power Spectral Density (PPSD) for Islanding Detection • The definition of the PPSD (3) The signal energy is given by (4) The proportional Power Spectral Density (5)

  13. Comparison of PPSD of voltage periods in grid-connected and islanding operation Fig. 7 Period variation in grid-connected operation. Fig. 8 PPSD of voltage periods in grid-connected operation Fig. 9 Period variation in islanding operation Fig. 10 PPSD of voltage periods in islanding operation

  14. The Proportional Energy Fig. 11 A lab testing system for single phase islanding operation Fig. 12 Proportional energy in frequency band from radian

  15. 5kW Single-Phase Inverter

  16. The Lab Test System forSingle Phase Islanding Operation

  17. Fig. 13 Covariance in grid-connected operation Fig. 14 Covariance in islanding operation • Covariance Index for Islanding Detection • Comparison of covariance function in grid-connected operation and islanding operation • Proposed covariance estimator • the covariance between the current command periods and the actual voltage periods can be taken as a significant islanding indicator (6)

  18. Fig. 15 A lab testing systemforthree phase islanding operation Fig. 16 Covariance changes during islanding operation

  19. Adaptive Logic Phase Shift (ALPS) or Adaptive Reactive Power Shift (ARPS) Algorithm • Slip-Mode Shift As a Basic Phase Shift Fig. 17 SMS phase shift

  20. Probability of suspicious islanding The probability of or Is greater than 0.6 • Additional Phase Shift is added • Reference Period (or Frequency) Stop and Resume Criteria

  21. Hybrid Anti-Islanding Algorithms • A hybrid of passive and active algorithms is to use passive islanding indicators such as PPSD and covariance to activate the active anti-islanding techniques such as ALPS and ARPS to move the frequency into the UFP/OFP trip window. The goal of this hybrid anti-islanding algorithm is to robustly trip the islanding operation while maintain a zero or the least disturbance in grid-connected operation.

  22. The flowchart of hybrid anti-islanding

  23. Lab Testing Results Fig. 18 Lab testing system for hybrid anti-islanding algorithm

  24. (1) Covariance changes after islanding operation (2) Probability of Cause and Effect after islanding operation (3) Additional D-axis current after islanding operation (4) Total D-axis current after islanding operation

  25. (5) Period shift after the islanding operation Fig. 19 Lab tests for hybrid anti-islanding algorithm

  26. 30kW Three Phase SVPWM Inverter System

  27. The Lab Test System for Three-Phase Islanding Operation

  28. Three-Phase Islanding Load

  29. Conclusion • A hidden gene concept is introduced in islanding detection • Proportional power spectral density of voltage periods can be used as a distinct islanding indicator • The effectiveness of the covariance islanding indicator is proved • ALPS and ARPS active anti-islanding algorithms are proposed • Hybrid of passive and active anti-islanding techniques can provide a way to robustly trip the islanding operation while maintain a zero or the least disturbance in grid-connected operation.

  30. Questions ??? Suggestions……

  31. [1] L. Chang, C. Diduch, and P. Cusack, “Development of standards for interconnecting distributed generators with electric power systems,” IEEE Canadian Conference on Electrical and Power Engineering, Montreal, May, 2003. [2] IEEE, Standard 1547™, Standard for Interconnecting Distributed Resources with Electric Power Systems, June 2003. [3] IEEE, Standard 929-2000, IEEE Recommended Practice for Utility Interface of Photovoltaic (PV) Systems, 2000. [4] J. Yin, L. Chang and C. Diduch, “Recent developments in islanding detection for distributed power generation,” in Proc. Large Engineering Systems Conference on Power Engineering, July 28-30, 2004, pp. 124-128. [5] R. M. Rifaat, “Critical considerations for utility/cogeneration inter-tie protection scheme configuration,” IEEE Trans. Industry Applications, vol. 31, no. 5, pp. 973-977, Sep./Oct. 1995. [6] M. E. Ropp, M. Begovic, A. Rohatgi, G. A. Kern, R. H. Bonn, Sr., and S. Gonzalez, “Determining the relative effectiveness of islanding detection methods using phase criteria and non-detection zones,” IEEE Trans. Energy Conversion, vol. 15, no. 3, pp. 290-296, Sept. 2000. [7] W. BOWER and M. ROPP, “Evaluation of islanding detection methods for photovoltaic utility-interactive power systems,” Report IEA PVPS T5-09: 2002. [8] J. Warin and W. H. Allen, “Loss of mains protection,” ERA Conference on Circuit Protection for Industrial and Commercial Installations, London, UK, pp. 4.3.1-12, 1990. [9] M. A. Refern, O. Usta, and G. Fielding, “Protection against loss of utility grid supply for a dispersed storage and generation unit,” IEEE Trans. Power Delivery, vol. 8, no. 3, pp. 948-954, July 1993. [10] M. A. Redfern, J. I. Barrett, and O. Usta, “A new microprocessor based islanding protection algorithm for dispersed storage and generation units,” IEEE Trans. Power Delivery, vol. 10, no. 3, pp. 1249-1254, July 1995. [11] F. Pai and S. Huang, “A detection algorithm for islanding-prevention of dispersed consumer-owned storage and generating units,” IEEE Trans. Energy Conversion, vol. 16, no. 4, pp. 346-351, Dec. 2001. [12] W. Freitas, W. Xu, C. M. Affonso and Z. Huang, “Comparative Analysis Between ROCOF and Vector Surge Relays for Distributed Generation Applications,” IEEE Trans. Power Delivery, vol. 20, no. 2, pp. 1315-1324, Apr. 2005. [13] P. O’Kane and B. Fox, “Loss of mains detection for embedded generation by system impedance monitoring,” Development in Power System Protection, 25-27th March 1997, Conference Publication No. 434, IEE 1997, pp.95-98. [14] M. Sumner, B. Palethorpe, D. W. P. Thomas, P. Zanchetta, and M. C. D. Piazza, “A technique for power supply harmonic impedance estimation using a controlled voltage disturbance,” IEEE Trans. Power Electronics, vol. 17, no. 2, pp. 207-215, Mar. 2002. • References:

  32. [15] M. E. Ropp, “Design Issue for Grid-Connected Photovoltaic System,” PhD., Georgia Institute of Technology, Atlanta, GA, 1998. [16] G. A. Kern, “SunSine300: Utility interactive AC module anti-islanding test results,” in Proc. 26th IEEE Photovoltaic Specialists Conf., pp. 1265-1268, 1997. [17] M. E. Ropp, M. Begovic, A. Rohatgi, “Analysis and performance assessment of the active frequency drift method of islanding prevention,” IEEE Trans. Energy Conversion, vol. 14, no. 3, pp. 810-816, Sept. 1999. [18] G. Hung, C. Chang, and C. Chen, “Automatic phase-shift method for islanding detection of grid-connected photovoltaic inverter,” IEEE Trans. Energy Conversion, vol. 18, no. 1, pp. 169-173, Mar. 2003. [19] Z. Ye, R. Walling, L. Garces, R. Zhou, L. Li, and T. Wang, “Study and Development of Anti-Islanding Control for Grid-Connected Inverters,” Report, National Renewable Energy Laboratory, NREL/SR-560-36243, May 2004. [20] V. John, Z. Ye, and A. Kolwalkar, “Investigation of anti-islanding protection of power converter based distributed generators using frequency domain analysis,” IEEE Trans. Power Electronics, vol. 19, no. 5, pp. 1177-1183, Sept. 2000. [21] J. Yin, L. Chang and C. Diduch, “A new adaptive logic phase-shift algorithm for anti-islanding protections in inverter-based DG systems,” IEEE Power Electronics Specialists Conference 2005, Recife, Brazil, June 13-16, 2005, pp. 231-236.

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