SFC Starting Performance Analysis of Large Variable Speed Pumped Storage Unit
Large variable-speed pumped storage units operate as electric motors under pumping conditions.During the start-up process,it is necessary to overcome the moments of resistance of the power generating motors and pump turbines,and it is necessary to drag the units to the grid-connected speed within a certain period of time.Therefore,it is crucial to adopt an effective starting method.Large variable-speed pumped storage unit electric starting methods include static frequency converter(SFC)starting,back-to-back starting and self-starting,of which SFC starting is one of the commonly adopted starting methods in pumped storage power stations,and variable-speed units can also be started with SFC configured for fixed-speed units.However,the variable-speed generating motor is a wound asynchronous motor with three-phase AC excitation technology,which is completely different from the fixed-speed unit in terms of model and excitation technology.At present,there are fewer research results related to the SFC starting for variable-speed generating motors at home and abroad,so there is an urgent need to carry out the research and analysis on the cooperation of variable-speed generating motors,SFC devices and AC excitation.The self-starting method is limited by the motor parameters and converter output,and the output torque capacity is small.The back-to-back starting method is often used as a backup starting method.So both of them are not applicable to the starting of large variable-speed pumped storage units of 400MW class and above.In this paper,starting from the analysis the principle of SFC starting of variable-speed generating motor,a numerical simulation model of SFC starting of variable-speed generating motor is constructed.The whole starting process of a 440MW pumped storage unit is carried out by using this simulation model,and the rule of change of the main physical quantities is obtained,which verifies the reliability of the numerical model.
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