C. Zhang, X. Zhao, X. Wang, X. Chai, Z. Zhang, and X. Guo, “A Grid Synchronization
PLL Method Based on Mixed Second- and Third-Order Generalized Integrator for DC Offset
Elimination and Frequency Adaptability,” in IEEE Journal of Emerging and Selected
Topics in Power Electronics, vol. 6, no. 3, pp. 1517-1526, Sept. 2018. DOI:10.1109/JESTPE.2018.2810499.