Analysis and optimization of abnormal command switching of steam regulating valve in MEH system of 350 MW power unit
During the operation of a 350 MW supercritical unit,the inlet steam regulating valve command of the feed water pump turbine suddenly swayed,in order to prevent the feed water flow swing caused by the water-coal ratio imbalance,the MEH was urgently cut to the valve control,butthe sudden closure of the steam inlet valve further caused water cut-off on the boiler heating surface.Based on the analysis of the accident process and the control circuit of MEH inlet steam regulating valve,it is clear that the pressure swing of auxiliary steam header is the main cause of MEH regulating valve swing,meh valve control command fast off is due to valve control tracking circuit timing anomalies.After the optimization of the valve-controlled tracking loop of MEH,the undisturbed switching tests of valve-controlled,speed-controlled and remote-controlled modes are carried out,the important hidden problem of non-tracking of valve position commands caused by timing anomalies is effectively solved.
feed water pump turbineinlet steam regulating valveswingvalve controlMEH
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