Online phase margin compensation strategy for a grid-tied inverter to improve its robustness to grid impedance variation

Chen Zheng; Lin Zhou; Xirui Yu; Bin Li; Jinhong Liu

Online phase margin compensation strategy for a grid-tied inverter to improve its robustness to grid impedance variation

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Author(s): Chen Zheng ¹ ; Lin Zhou ¹ ; Xirui Yu ¹ ; Bin Li ¹ ; Jinhong Liu ¹
- Affiliations: 1: State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, No.174 Shazheng Street Shapingba District, Chongqing, People's Republic of China
Source: Volume 9, Issue 4, 30 March 2016, p. 611 – 620
DOI: 10.1049/iet-pel.2015.0196 , Print ISSN 1755-4535, Online ISSN 1755-4543

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Received 23/03/2015, Accepted 05/08/2015, Revised 12/07/2015, Published 30/03/2016

According to studies on active damping and the stability margin, grid impedance variation does not make active damping ineffective; instead, it attenuates the stability margin. The harmonic resonance mechanism of grid-tied inverters has been revealed by researching the influence of stability margin reduction on harmonic current amplification coefficients around the cut-off and phase crossover frequencies. With the stability margin decreasing, amplification to harmonics around relevant frequencies is strengthened. The harmonic resonance around the cut-off frequency is triggered as the stability margin decreases to zero. An online phase margin (PM) compensation strategy is proposed in this study to improve system robustness to grid impedance variation. The strategy is implemented by the lead network to enhance the phase and the proportional component to regulate the cut-off frequency according to the grid impedance measured online. Hence, the system can be maintained with a sufficient PM to mitigate the harmonic resonance caused by grid impedance. Simulation and experimental results validate the theoretical analysis presented in this study. Comparisons show that the proposed strategy is superior to the zero compensation strategy in suppressing the harmonic resonance.

References

1. 1)
  - 16. Yang, D., Ruan, X., Wu, H.: ‘Impedance shaping of the grid-connected inverter with LCL filter to improve its adaptability to the weak grid condition’, IEEE Trans. Power Electron., 2014, 29, (11), pp. 5795–5805 (doi: 10.1109/TPEL.2014.2300235).
2. 2)
  - 13. He, Li, J.W., Y.W., Bosnjak, D., et al: ‘Investigation and active damping of multiple resonances in a parallel-inverter-based microgrid’, IEEE Trans. Power Electron., 2013, 28, (1), pp. 234–246 (doi: 10.1109/TPEL.2012.2195032).
3. 3)
  - 17. Xu, J.M., Xie, S.J., Tang, T.: ‘Improved control strategy with grid-voltage feedforward for LCL-filter-based inverter connected to weak grid’, IET Power Electron., 2014, 7, (10), pp. 2660–2671 (doi: 10.1049/iet-pel.2013.0666).
4. 4)
  - 8. Pan, D., Ruan, X., Bao, C., et al: ‘Optimized controller design for LCL-type grid-connected inverter to achieve high robustness against grid-impedance variation’, IEEE Trans. Ind. Electron., 2015, 62, (3), pp. 1537–1547 (doi: 10.1109/TIE.2014.2341584).
5. 5)
  - 2. Heydt, G.T.: ‘The next generation of power distribution systems’, IEEE Trans. Smart Grid, 2010, 1, (3), pp. 225–235 (doi: 10.1109/TSG.2010.2080328).
6. 6)
  - 15. Jia, Y., Zhao, J., Fu, X.: ‘Direct grid current control of LCL-filtered grid-connected inverter mitigating grid voltage disturbance’, IEEE Trans. Power Electron., 2014, 29, (3), pp. 1532–1541 (doi: 10.1109/TPEL.2013.2264098).
7. 7)
  - 2. Marco, L., Teodorescu, R., Blaabjerg, F.: ‘Stability of photovoltaic and wind turbine grid-connected inverters for a large set of grid impedance values’, IEEE Trans. Power Electron., 2006, 21, (1), pp. 263–272 (doi: 10.1109/TPEL.2005.861185).
8. 8)
  - 22. Liserre, M., Blaabjerg, F., Teodorescu, R.: ‘Grid impedance estimation via excitation of LCL-filter resonance’, IEEE Trans. Ind. Appl., 2007, 43, (5), pp. 1401–1407 (doi: 10.1109/TIA.2007.904439).
9. 9)
  - 16. Mukherjee, N., De, D.: ‘Analysis and improvement of performance in LCL filter-based PWM rectifier/inverter application using hybrid damping approach’, IET Power Electron., 2013, 6, (2), pp. 309–325 (doi: 10.1049/iet-pel.2012.0032).
10. 10)
  - 20. Erickson, R.W., Maksimovic, D.: ‘Fundamentals of power electronics’ (Kluwer, Norwell, MA, USA, 2001, 2nd edn.), pp. 331–408.
11. 11)
  - 11. Li, B., Yao, W., Hang, L., Tolbert, L.M.: ‘Robust proportional resonant regulator for grid-connected voltage source inverter (VSI) using direct pole placement design method’, IET Power Electron., 2012, 5, (8), pp. 1367–1373 (doi: 10.1049/iet-pel.2012.0102).
12. 12)
  - 9. Enslin, J.H.R., Heskes, P.J.M.: ‘Harmonic interaction between a large number of distributed power inverters and the distribution network’, IEEE Trans. Power Electron., 2004, 19, (6), pp. 1586–1593 (doi: 10.1109/TPEL.2004.836615).
13. 13)
  - 18. Wang, X., Blaabjerg, F., Liserre, M., et al: ‘An active damper for stabilizing power-electronics-based AC systems’, IEEE Trans. Power Electron., 2014, 29, (7), pp. 3318–3329 (doi: 10.1109/TPEL.2013.2278716).
14. 14)
  - 2. Jinn-Chang, W., Kuen-Der, W., Hurng-Liahng, J., et al: ‘Small-capacity grid-connected solar power generation system’, IET Power Electron., 2014, 7, (11), pp. 2717–2725 (doi: 10.1049/iet-pel.2014.0015).
15. 15)
  - 21. Cespedes, M., Sun, J.: ‘Online grid impedance identification for adaptive control of grid-connected inverters’. Proc. Conf. IEEE ECCE. Applications, USA, September, 2012, pp. 914–921.
16. 16)
  - 8. Tang, Y., Loh, P.C., Wang, P., Choo, F.H., Gao, F.: ‘Exploring inherent damping characteristic of LCL-filters for three-phase grid-connected voltage source inverters’, IEEE Trans. Power Electron., 2012, 27, (3), pp. 1433–1443 (doi: 10.1109/TPEL.2011.2162342).
17. 17)
  - 6. Tang, Y., Loh, P.C., Wang, P., et al: ‘Improved one-cycle-control scheme for three-phase active rectifiers with input inductor-capacitor-inductor filters’, IET Power Electron., 2011, 4, (5), pp. 603–614 (doi: 10.1049/iet-pel.2010.0193).
18. 18)
  - 23. Sun, X.F., Chen, J.X., Josep, M., et al: ‘Fundamental impedance identification method for grid-connected voltage source inverters’, IET Power Electron., 2014, 7, (5), pp. 1099–1105 (doi: 10.1049/iet-pel.2013.0398).
19. 19)
  - 15. Xu, J., Xie, S., Tang, T.: ‘Evaluations of current control in weak grid case for grid-connected LCL-filtered inverter’, IET Power Electron., 2013, 6, (2), pp. 227–234 (doi: 10.1049/iet-pel.2012.0192).
20. 20)
  - 3. Jian, S.: ‘Impedance-based stability criterion for grid-connected inverters’, IEEE Trans. Power Electron., 2011, 26, (11), pp. 3075–3078 (doi: 10.1109/TPEL.2011.2136439).
21. 21)
  - 5. Koutroulis, E., Blaabjerg, F.: ‘Methodology for the optimal design of transformerless grid-connected PV inverters’, IET Power Electron., 2012, 5, (8), pp. 1491–1499 (doi: 10.1049/iet-pel.2012.0105).
22. 22)
  - 12. Agorreta, J., Borrega, M., Lopez, J., et al: ‘Modelling and control of N-paralleled grid-connected inverters with LCL filter coupled due to grid impedance in PV plants’, IEEE Trans. Power Electron., 2011, 26, (3), pp. 770–785 (doi: 10.1109/TPEL.2010.2095429).
23. 23)
  - 14. Mohamed, Y.A.-R.I.: ‘Suppression of low- and high-frequency instabilities and grid-induced disturbances in distributed generation inverters’, IEEE Trans. Power Electron., 2011, 26, (12), pp. 3790–3803 (doi: 10.1109/TPEL.2011.2161489).

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Online phase margin compensation strategy for a grid-tied inverter to improve its robustness to grid impedance variation

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