State estimation of power grid under smart grid integration based on FFCD-SOGI-PLLXiangyu ZHOU, Zhen ZHANG, Ruiqing MA, Chunling WU, Yong LU, Kang XIANGLI and Danqing WANGJNWPU, 40 6 (2022) 1343-1351DOI: https://doi.org/10.1051/jnwpu/20224061343