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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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outline
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
slide3

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

slide4

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

slide5

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
slide6
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)
slide7
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
slide8
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)

slide9

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)

slide10
The Frequency Response of The System

Fig. 4 System model for response to disturbance and noise

Fig. 5 Bode plot of system transfer function

slide12
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)

slide13
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

slide14
The Proportional Energy

Fig. 11 A lab testing system for single phase islanding operation

Fig. 12 Proportional energy in frequency band from radian

slide17

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)

slide18

Fig. 15 A lab testing systemforthree phase islanding operation

Fig. 16 Covariance changes during islanding operation

slide19

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

slide20

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
slide21

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.
slide23
Lab Testing Results

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

slide24

(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

slide25

(5) Period shift after the islanding operation

Fig. 19 Lab tests for hybrid anti-islanding algorithm

slide29
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.
slide30

Questions ???

Suggestions……

slide31

[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:
slide32

[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.