Study On Stability And Regulation Quality Of Hydropower System Under Complex Layout Condition

With the rapid development of China’s economy,the demand for electric energy increases sharply.As an important way of generating electric energy,the stability and regulation quality of hydropower system are very important for the design and safe and stable operation of the whole hydropower station.At present,the transfer function method and the state space method are mostly used in the studies on the stability of small fluctuations and the regulation quality of the hydropower system.However,when the layout of the hydropower system is complex,these two methods are difficult to deduce the transfer function or to construct the state matrix.In view of the difficulties in the study of small fluctuation’s stability and regulation quality of complex hydropower system,the following aspects are studied in this paper.1.The expression of hydraulic impedance is derivedOn the basis of the expression of impedance put forward by predecessors,combining with the linearized model of turbine,the mathematical model of generator and the governor equation,the expression of the hydraulic impedance of the unit is deduced,and arranged into the form of transfer matrix equation,which lays a foundation for building the overall matrix and solving a stability region.2.The stability of a hydroelectric power system with complex layout is studiedThe overall matrix method has the characteristics of accurate solution for the stability region of complex hydroelectric power system,and can adapt to different power station layout(only the corresponding transfer matrix order of each module of the system needs to be modified),which is of great convenience for the calculation and analysis of the operation stability of hydropower stations.Therefore,based on the advantages of the overall matrix method,this paper uses the overall matrix method to construct the overall matrix of a two generating units sharing the same conduit and a two generating units sharing the same conduit with the upstream and downstream double surge chambers of pumped-storage power station,and to solve the stability region.The accuracy of the overall matrix method is verified by establishing the transfer function of a simple hydropower station with one generating unit and comparing the results of the transfer function method and Simulink numerical simulation with the overall matrix method.In addition,the stability region of the system with different parameters such as pipeline parameters,operating point,governor parameters,stability margin and area of surge chamber is further calculated and analyzed,and the variation rule of stability region is summarized,which provides a reference for the design and operation strategy of the power station.3.The regulation quality of hydraulic power system with complex layout is studiedSince the transfer function method requires the inverse Laplace transform to perform the time domain analysis,and the state space method is difficult to build a state matrix,Simulink is used in modeling and analyzing regulation quality in this paper,through the Simulink simulation platform for a two generating units sharing the same conduit and a two generating units sharing the same conduit with the upstream and downstream double surge chambers of pumped-storage power station have carried on the modeling and simulation,analyzed regulation quality of units when the pipeline parameters,operating point,governor parameters,stability margin and area of surge chamber are different,The results show that the governor parameters have a great influence on the regulation quality of the system and the area of surge chamber has a great influence on the speed fluctuation of tail wave.