UDE Based Robust Control of Grid Tied Inverters

Abstract

In this paper, a modified (proportional-integral) PI control is suggested to improve current tracking performance of three-phase grid-tied inverters (GTI). Presence of the L filter between inverter and grid, makes complex to design a controller with proper parameters, due to characteristics of the filter. Clasical PI control depends on an accurate dynamical model, thus its performance is deteriorated by parametric uncertainties, unmodelled dynamics and external disturbances, when operating conditions affect the filter parameters. To solve this problem, uncertainty and disturbance estimator based PI current control approach is proposed for grid-tied inverters, which provides robustness against to parametric perturbations. An UDE based observer that has been adopted into the PI current loop is used to eliminate lumped disturbances and the steady-state tracking error of current states, which can enhance the robustness of the control performance. Then, parameter design method, stability and robustness analysis are explored and presented. Performance comparison among the clasical PI and proposed control scheme. Efficacy and performance of the proposed approach are carried out by simulations and experiments. Experimental results show that effectiveness of the suggested control method against parametric uncertainties and disturbances are succesfully validated. Besides, the precise current tracking performance with zero steady state error has been reached.

Keywords

• Uncertainty
• Disturbance
• Robust Control
• Inverters

References

1. M. Lindgren and J. Svensson, “Control of a voltage-source converter connected to the grid through an LCL-filter-application to active filtering,” in Proc. IEEE Power Electron. Spec. Conf., May 1998, pp. 229–235.
2. W. Li, X. Ruan, D. Pan, and X. Wang, “Full-feedforward schemes of grid voltages for a three-phase LCL-type grid-connected inverter,” IEEE Trans. Ind. Electron., vol. 60, no. 6, pp. 2237–2250, Jun. 2013.
3. Q. Zhao, Y. Ye, G. Xu, and M. Zhu, “Improved repetitive control scheme for grid-connected inverter with frequency adaptation,” IET Power Electron., vol. 9, no. 5, pp. 883–890, Apr. 2016.
4. R. Teodorescu, F. Blaabjerg, M. Liserre, and P. C. Loh, “Proportional resonant controllers and filters for grid-connected voltage-source converters,” in Proc. Elect. Power Appl., vol. 153, no. 5, pp. 750–762, Sep. 2006.
5. S. Tong, Y. Li, and S. Sui, “Adaptive fuzzy tracking control design for SISO uncertain nonstrict feedback nonlinear systems,” IEEE Trans. Fuzzy Syst., vol. 24, no. 6, pp. 1441–1454, Dec. 2016
6. N. Kumar, T. K. Saha, and J. Dey, “Sliding-mode control of PWM dual inverter-based grid-connected PV system: Modeling and performance analysis,” IEEE J. Emerg. Sel. Topics Power Electron., vol. 4, no. 2, pp. 435–444, Jun. 2016.
7. E. Sariyildiz and K. Ohnishi, “Stability and robustness of disturbanceobserver- based motion control systems,” IEEE Trans. Ind. Electron., vol. 62, no. 1, pp. 414–422, Jan. 2015.
8. J. Han, “From PID to active disturbance rejection control,” IEEE Trans. Ind. Electron., vol. 56, no. 3, pp. 900–906, Mar. 2009.

9. B. Ren, Q.-C. Zhong, and J. Dai, “Asymptotic reference tracking and disturbance rejection of UDE-based robust control,” IEEE Trans. Ind. Electron., vol. 64, no. 4, pp. 3166–3176, Apr. 2017.
10. J. Ren, Y. Ye, G. Xu, Q. Zhao, and M. Zhu, “Uncertainty-and-disturbanceestimator- based current control scheme for PMSM drives with a simple parameter tuning algorithm,” IEEE Trans. Power Electron., vol. 32, no. 7, pp. 5712–5722, Jul. 2017.
11. Q.-C. Zhong, A. Kuperman, and R. K. Stobart, “Design of UDE-based controllers from their two-degree-of-freedom nature,” Int. J. Robust Nonlinear Control, vol. 21, no. 17, pp. 1994–2008, Nov. 2011.
12. J. Chen, B. Ren, and Q.-C. Zhong, “UDE-based trajectory tracking control of piezoelectric stages,” IEEE Trans. Ind. Electron., vol. 63, no. 10, pp. 6450–6459, Oct. 2016.
13. B. Ren, Y.Wang, and Q.-C. Zhong, “UDE-based control of variable-speed wind turbine systems,” Int. J. Control, vol. 90, no. 1, pp. 137–152, 2017.
14. J. Ren, Y. Ye, G. Xu, Q. Zhao, and M. Zhu, “Uncertainty and disturbance estimator-based current control scheme for PMSM drives with a simple parameter tuning algorithm,” IEEE Trans. Power Electron., vol. 32, no. 7, pp. 5712–5722, Jul. 2017,
15. I. Aharon, D. Shmilovitz, and A. Kuperman, “Robust output voltage control of multimode non-inverting DC-DC converter,” Int. J. Control, vol. 90, no. 1, pp. 110–120, 2017.
16. S. Y. Gadelovits, Q.-C. Zhong, V. Kadirkamanathan, and A. Kuperman, “UDE-based controller equipped with a multi-band-stop filter to improve the voltage quality of inverters,” IEEE Trans. Ind. Electron., vol. 64, no. 9, pp. 7433–7443, Sep. 2017.
17. Y. Ye and Y. Xiong, “UDE-based current control strategy for LCCL-type grid-tied inverters,” IEEE Trans. Ind. Electron., vol. 65, no. 5, pp. 4061– 4069, May 2018.
18. R. Errouissi, M. Ouhrouche, W.-H. Chen, and A. M. Trzynadlowski, “Robust nonlinear predictive controller for permanent-magnet synchronous motors with an optimized cost function,” IEEE Trans. Ind. Electron., vol. 59, no. 7, pp. 2849–2858, Jul. 2012