Operation Performance Of Typical Transition Process Of Pumped Storage Power Station

Pumped storage unit is a two-way running unit with both pumping and power generation functions.It undertakes the tasks of peak regulation,frequency regulation and phase regulation in the power system.It is precisely because pumped storage power stations have a similar role as a "stabilizer" in the power system,so the stable operation performance of pumped storage power stations is particularly important.There are as many as 24 operating conditions for pumped storage power stations,and they experience at least 2,500 start-stops each year.They may operate under various non-design conditions.How to ensure that pumped storage units are efficient under typical transition process conditions Stable operation has become the focus of research.In this thesis,three typical transitional processes are selected: pumped-storage unit start-up,phase modulation and forward power,pump power failure,and vane refusal.The non-linear mathematical models applicable to the above transitional processes are established,and pumping is analyzed.The dynamic evolution law of various parameters of the energy storage power generation system,and suggestions are given to affect the stable performance of the unit.The main structure of this thesis is as follows:(1)Performance analysis of the transition process of pumped storage units under pressure pulsation.Innovatively introduce the pressure pulsation at this time into the pump turbine control system,and establish a mathematical model of the pumped storage unit considering the pressure pulsation.Based on this mathematical model,a numerical simulation platform was used to simulate the dynamic characteristics of the unit's speed,flow,and voltage during the startup transition process,and the stability performance of the unit was analyzed using the stability performance index.Whether to consider the pressure pulsation as a variable,the factors that affect the stability of the unit under pressure pulsation are given,and provide corresponding theoretical guidance for the actual construction of the project.(2)Performance analysis of the phase transition and forward electricity transfer process of pumped storage power stations.Based on the full characteristic curve of the pump and turbine,the transfer coefficient in the transition process was obtained by polynomial fitting.The transfer coefficient was used to obtain the guide vane opening and the flow rate,speed and torque at the corresponding time.Mathematical model of the process.In order to analyze the comprehensive influence of the switching time and the opening rule of the guide vanes on the overall operating performance of the unit,six typical experimental cases were selected,and the optimal switching time and opening law were found through comparative analysis.(3)Performance analysis of the transition process of the pumped storage power station when the pump is powered off and the guide vanes are refused to move.Based on the full characteristic curve of the pump-turbine,a mathematical model was obtained for the pump-storage power station's pump failure and the guide vane refusing to move.The change law of the unit's external characteristic parameters under this transition process is shown in the form of a bifurcation diagram.From the perspective of the internal and external characteristics,the evolution of the unit's parameter after the power is cut off is analyzed.The main parameters that affect the stability of the unit are determined using the Helvetitz judgment method.The influencing factors are compared and analyzed to find the key parameters that affect the stability performance,and provide technical guidance for engineering practice.