Research On Control Strategy And Test For Isolated Grid Operation Of Thermal Power Unit

When large-scale faults occur in the power network, if predetermined and reasonable splitting measures are worked out to maintain the isolated power grid stable operation,which can guarantee the important load of the city normal power supply and can contribute to the global electric power network gradual recovery. However, the isolated grid operation is a special operating mode under certain conditions, and most of the operating characteristics and control strategies power plants have not consider this function. Moreover, the thermal power unit have a large proportion in regional power network, with its complex control technology and difficult test, when the situation appears, the local power plants are difficult to support the loads of the isolated power grid. So, it has very important significance to research on the control strategy of fossil plant units to improve the security and the reliability of the power supply of the isolated power grid.The main constraint conditions of the isolated grid operation of thermal power t units are discussed in this paper, the power system operating mode and automatic safety devices are the main constraint conditions of load side, the control mode, regulation characteristics and protection device of unit are the main constraint conditions of unit side. The simulation model of the isolated grid operation is structured, and model parameters based on measured and identification is given. The response characteristics of unit under different parameters settings are discussed,when the isolated network was formed with large unbalanced power, and parameter setting value which beneficial to stable operation of isolated network are given. The control logic of isolated grid operation of thermal power unit are improved, logic judgment of isolated network, predictive control of acceleration of rotor and hierarchical control of primary frequency regulation are proposed. Combined with the islanding risk of GuangDong power grid, The application of control strategy of isolated grid operation which according to isolated network mode are analyzed. With the control strategy of isolated grid operation as a guidance, an islanding examination is conducted.