Research On Stability Of Steam Turbo-generator Set On Parallel Operation

With the rapid development of modern industry, the science and technology are enteringthe speedy development period. And then, the corresponding marine technology is evolvedaccordingly. The overall trend in modern ship technology is informatization, giant, speedinessand industrialization. With the tonnage of ship bigger and bigger and the increased marinehigh-power load, the requirement of control accuracy of ship synchronous generatorexcitation control system is gradually raised. In this paper, H_∞control theory is used tostudy the stability of ship power system, because it can solve the control problem ofperformance deterioration which is caused by uncertainty of the control object andperturbation within range of the model parameter.The mathematical model of the steam turbine in ship power station is built in this article.Combined with direct feedback linearization method, the nonlinear H_∞speed controller ofturbo generator set has been set up. According to the experience, the weighting function isconfirmed and a detailed study is carried out to the problem in the design of systemoptimization. Through the simulation of suddenly increasing and decreasing load to the model,the dynamic performance of nonlinear H_∞controller is verified successful and its prospectis bright.Through the mathematical analysis for the synchronous generator and excitation system,the mathematical model has been built. Then, mixed sensitivity method of the H_∞controltheory is used to design the H_∞excitation controller of synchronous generator. Theperformance of mixed sensitivity problem requirement and weighting function selection wereintroduced in detail and verified the performance of the system by the bode plot. Through thesimulation of sudden increasing and decreasing load to the excitation system, it is verified thatthe designed H_∞excitation controller is reasonable and it can obviously improve the systemdynamic accuracy and robustness. Thus, the voltage control of system received the desiredeffect.In this paper, the coupled relation between the speed of steam turbine and the voltage ofsynchronous generator is considered and a detailed analysis has been done for the steamturbine speed control system and the synchronous generator excitation system. And themathematical model of turbo generator set has been built to reduce the coupled relation ofthem. On this basis, the model of one turbo generator set combination control system has beenbuilt. Through comparative analysis, the designed combination controller could not only control the speed and voltage effectively, but also increase the dynamic precision of systemand the performance of suppressing the disturbance.In this paper, based on the research of one turbo generator set system, the simulation ofdouble set parallel system has been done and the robust controller has been applied to it. Theresult of simulation shows that the active power between two generators is distributedreasonable. The speed and terminal voltage of each generator have also been controlled well.