Power system islanding is the last defense in protecting power grids from wide-area blackout. The operation of an island power system differs in many ways from that of large interconnected networks. The research frequency is important significance to improve the security and reliability of the isolated power grid. The characteristics of islanding operation are introduced in this paper; the control methods of hydraulic turbine, steam turbine are described. The contributions of primary frequency control, OPC, over frequency generator tripping, UFLS, secondary frequency regulation made to islanding operation are analyzed. The state of islanded power grids and shortcomings of stability control technology at home and abroad are summarized comprehensively，the research direction of system frequency control in the future is prospected in this paper.
展开▼
