Energetica India nº91 July August 2020

WIND POWER Obtaining an optimized control structure Low time (~100 ms) is needed to generate and analyze one LTI system. That brings the possibility to test high number of different control parameters and algorithms with all possible different grid and generator combinations, obtaining stability maps and dynamical behaviours. The optimal control structure and its parametrization are se- lected, which are stable with all possible grid and generator casuistic and present best dynamical behaviour. Validation of the control structure The selected control structure and its parametrization are val- idated with SiL&HiL simulation platforms together with an au - tomated testing procedure, to eliminate uncertainties due to simplifications and linearization of the control algorithms when generating the LTI model. Conclusions The use of LTI models is proposed to anticipate complex net - work issues. These LTI models are generated to each partic- ular grid, generator and control algorithm and parameter ca- suistics, allowing to check in a fast way the stability and the dynamic behaviour of the whole system. Simplifications must be done in order to generate the LTI mod - els. Switching and dead time are neglected, and non-linear control algorithms must be linearized. In spite of these simplifi - cations, the LTI model and real system responses have a good equivalence. Through simulation sweeps using LTI models, an optimal con- trol structure can be selected, that assures stability with all possible grid and generator casuistics and has acceptable dynamical behaviour. The selected control structure and its parametrization is finally validated using SiL / HiL simulation platforms. In this way, the good performance of the selected control structure is totally guaranteed References D. Velasco, J. Lopez, “Discrete-Time Domain Modeling of DQ-Frame Cur - rent-Controlled Systems through easy Implementation,” 2018 IEEE 19th Workshop on Control and Modeling for Power Electronics (COMPEL), Pad - ua, 2018, pp. 1-7. D. Velasco, “Modelización de parques eólicos conectados a redes débiles,” 2019. PhD thesis, Public University of Navarre, Pamplona, Spain. L. Harnefors, X. Wang, A. G. Yepes and F. Blaabjerg, “Passivity-Based Sta - bility Assessment of Grid-Connected VSCs—An Overview,” in IEEE Journal of Emerging and Selected Topics in Power Electronics, vol. 4, no. 1, pp. 116-125, March 2016. D. Dong, B. Wen, D. Boroyevich, P. Mattavelli and Y. Xue, “Analysis of Phase-Locked Loop Low-Frequency Stability in Three-Phase Grid-Connect- ed Power Converters Considering Impedance Interactions,” in IEEE Trans- actions on Industrial Electronics, vol. 62, no. 1, pp. 310-321, Jan. 2015. A. Lorea, J. Aguirrezabal, “Development of INGECON® WIND LV Power Converter for DFIG topology Wind Turbines up 5.X MW, “ Wind Europe, 2019. J. M. Maciejowsky, “Mutlivariable feedback desing (1. edition). Boston, USA. Pearson Education, 1989. J. Kukkola, M. Hinkkanen, K. Zenger, “Observer-based state-space current controller for a grid converter equipped with an LCL filter: Analytical method for direct discrete-time design,” IEE Trans. Ind. Appl. 51, 4079-4090, 2015. X. Li, J. Fang, Y. Tang, X. Wu, Y. Geng, “Capacitor-voltage feedforward with full delay compensation to improve wead grids adaptability of LCL-filtered grid-connected converters for distributed generation systems,” IEE ETrans. Power Electron. 33, 749-764, 2018. C. Zhang, X.F. Wang, F. Blaajberg, W.S. Wang, C. Liu, “The influence of phase-locked loop on the stability of single-phase grid connected inverter,” Proceedings paper presented on IEEE Energy Conversion Congress and Exposition. Montreal, Canada. 4737-4744, 2015. Figure 2. Real and LTI model current response comparison Figure 3. Stability map (left) and dynamic behavior (right) Figure 4. SiL model (left) and HiL simulation bench (right) energetica INDIA- July-Aug_2020 39