| The electric braking device plays an important role in improving the transient stability of the generator set,especially in the case of load rejection.Therefore,it is of great significance to study the electric braking device of generator set.The traditional electric braking device is a energy-consuming device,which consumes the kinetic energy of the generator rotor through the resistance after the load is dumped.Energy storage type electric braking device is proposed in this paper,using the super capacitor to generator rotor kinetic energy stored by the momentum again after motor recovery interconnection will be stored energy release back into the grid,this paper called SCBD.The research shows that SCBD can not only improve the transient stability of the generator system,but also compensate the power of the system and play the function of STACOM.In this paper,the hydrogenerator is taken as the research object to study the integrated coordinated control between SCBD and hydrogenerator,and the influence of SCBD on the transient stability of hydrogenerator system and the power compensation function are analyzed through the simulation results.In addition,SCBD is also applied to the load side to further verify the power compensation function of SCBD.This paper mainly completes the following tasks:1.Starting from the schematic diagram of SCBD,the third-order accurate mathematical model of SCBD containing the dc voltage at the side of the supercapacitor under the dq0 coordinate is deduced.Then,taking the hydrogenerator as the research object,and according to the structure diagram of SCBD and generator connection,the eight-order nonlinear comprehensive control system model including generator excitation,speed regulation controlsystem and SCBD is established.2.According to the characteristics of the integrated control system model,selection of differential algebraic nonlinear control method for control strategy,completed DAMNC controller design of the control system,the system of nonlinear control law u.Built by using MATLAB simulation system,and the linear optimal control(LOC)design the controller,to check the effectiveness of the system model and the superiority of the designed control law u,and through the three-phase short-circuit disturbance simulation SCBD influence on system transient stability,through regulating and adjustable work such as small disturbance test certificate II SCBD power compensation function.3.The model of SCBD is established by using the switch function method,which extends the modeling method of SCBD.And in order to avoid a multi-index nonlinear control method in the C parameter configuration,reduce the number of controller parameters configuration,reduce reliance controller on the system constraints,this article will applie the method of NCCOHF to nonlinear controller design,broaden the designing idea of the SCBD and generator integrated control research.Based on NCCOHF method,the system was simulated with and without SCBD,which further verified the effectiveness of SCBD in improving the transient stability of the system.4.The application of SCBD on the load side was studied,and the power compensation function of SCBD was further verified. |
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