The use of frequency converters on three-circuit ferroresonant circuits Bobokul Shaymatov, Maktuba Rakhmatova, Sardor Komilov and Dilnoza Qurbonova E3S Web Conf., 264 (2021) 05019 Published online: 02 June 2021 DOI: 10.1051/e3sconf/202126405019