Construction of Energy Flow Model for Direct Drive Fan Grid-connected System

As new energy equipment with wind power as the main body occupies a dominant position in the energy supply side, the high-order and strong interaction characteristics of the power system dominated by the control link gradually become prominent. Especially during the fault period, the mutation of the system balance point leads to the further intensification of the interaction between different control links.lt poses a threat to the stability of power system-However, at present, there is no suitable fan grid- connected model that can accurately describe the strong interaction characteristics between different control links of the system during the fault period. The traditional modeling method is difficult to achieve both high order and interaction characteristics of the system, resulting in the subsequent analysis cannot obtain accurate results.In order to solve the problem of the lack of reliable modeling scheme in the fault period of direct drive fans, this paper proposes a reduced order model of direct drive fans based on the dynamic energy flow of the system. The model is based on the dynamic energy flow of the system, focusing on the strong interaction between the control systems and the change trend, and the interaction characteristics of energy are used to decoupage the high order system.The specific steps are as follows: Firstly, according to the energy storage of each part of the system during the failure period, the grid-connected system is divided into subsystems based on storage units, and the dynamic mathematical model of each subsystem is established.Then, the first integral method is used to construct the dynamic energy units of each subsystem, and the interaction between the energy units is analyzed to determine the influence path of each unit.On this basis, the interaction characteristics of energy are used to reduce the order of the system, and the high order energy system is divided into a low order system dominated by different energy units, so as to obtain a simplified energy flow model under the fault scenario.Finally, the reliability of the model is verified by simulation.