Research On Dynamic And Seismic Performance Of 660MW Thermal Power Generator Structure

At present,thermal power is the main form of power generation in China,and the safe operation of power stations is of vital importance.Turbine generator support structure,as an important support for bearing generator units,shafting and other unit equipment,plays a decisive role in the smooth operation of the steam turbine.During the design,there are higher requirements for the dynamic characteristics and seismic performance of the supporting structure of thermal power generators.Due to the differences in the design,manufacturing process,and support structure layout of unit equipment,it is particularly important to conduct separate experimental research on support structures with specific structural arrangements.At the same time,according to the relevant national regulations,the test results meet the relevant national specifications for dynamic performance before actual engineering construction can be carried out.This paper takes a 660MW turbo-generator support structure of an actual thermal power station in China as the research background,and makes a 1:10 scale model in accordance with the support structure drawings provided by the Design Institute.The main research contents and conclusions are as follows:(1)The modal test of the support structure using the spatial three-way random excitation method gives the natural vibration characteristics of the support structure,which mainly include the natural frequency,mode shape,and damping ratio.Its natural frequency is sparsely distributed in the operating frequency range(50Hz±25%).In the low-frequency region,the mode is mainly dominated by the translation and torsion of the roof as a whole;in the high-frequency region,local bending,torsion,and vertical bending vibration of the structure are the main modes,but the distribution is relatively sparse.This distribution is more favorable for the safe operation of the steam turbine.(2)The modal test is performed on the scale model of the supporting structure,and the obtained results are analyzed by the root-mean-square analysis of the linear displacement of the vibration and the velocity of the vibration.The dynamic characteristic parameters of the prototype of the supporting structure are converted according to the similar ratio,and the corresponding amplitude curve is drawn.The test results show that the maximum linear vibration displacement of the support structure is23.40?m during the start-up phase;the maximum linear vibration displacement of the support structure is 17.31?m within the operating speed range.The root-mean-square value of the maximum vibration speed is 3.33mm/s.The linear displacement of the support structure and the root-mean-square value of the vibration speed meet the requirements of the relevant national regulations.(3)The bearing support where the supporting structure is connected to the unit is hammered.The corresponding data through force sensors and acceleration sensors are collected,and the dynamic stiffness values and amplitude curve of the generator unit in the operating frequency band(37.5~62.5Hz)are intercepted and analyzed..The test results show that the minimum value of the dynamic stiffness at the bearing support of the supporting structure is 5.72×10~6kN/m,which meets the requirements of relevant regulations and proves that the ability of the supporting structure to resist deformation meets the actual engineering needs.(4)The pseudo-static test of low-cycle reciprocating loading on the support structure model is performed,and performance parameters such as hysteresis curve,stiffness,ductility,and energy consumption capacity of the support structure model are given.The hysteresis loop of the structure is full and the seismic performance is good;under the same load,no obvious stiffness degradation occurs;the large displacement ductility coefficient proves that the structure has good ductility performance.In the plastic phase,with the load displacement gradually increasing,the energy consumption capacity of the structure is significantly enhanced,and the structure has good seismic performance.