Nonlinear Control of PMSG Wind Turbine Systems

Wind energy conversion system under asymmetrical voltage failures: Analysis and nonlinear control

“…It should be noted that in Figure 4, dynamic expressions and blocks are related in the next way: Turbine and PMSG represent expressions (3)(4)(5)(6), DC link corresponds to (14), GCD + Line Filter indicates ( 8) and ( 9), Grid Power + Losses takes into account the resistive part of ( 8) and ( 9) and ( 11)and (12). Finally, PSC + SGSC means PSC in the converter at the PMSG side and DC link Control and GSC Control indicate Lyapunov Control at DC and at grid sides, respectively.…”

“…respectively, which means that active power oscillations are eliminated. However, equation (12), it is straightforward to see an unavoidable oscillatory behavior in the reactive power…”

“…New grid connection codes specifically require that WECS provide grid support in cases of abnormal conditions [5], with special stress in operation under unbalanced grid voltages [6]. In this sense, many interesting contributions about WECS operating under symmetrical and asymmetrical grid failures have been published in the specialized literature during the last years [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. In the particular case of PMSG-WECS, most of these approaches propose, during such grid voltage failures, reducing the wind power extraction at the generator side converter while delivering at the grid side the power required by the net despite the distorted voltage presence [7].…”