Cause Analysis and Measures of Tripping During ATT of a 1000 MW Ultra-supercritical Double Reheat Unit
A 1 000 MW ultra-supercritical double reheat unit experienced an abnormal drop in control(EH)oil pressure during a valve activity test(ATT),which led to the closure of all turbine control valves,triggering the generator reverse power protection and causing the unit to trip.The causes of the accident were analysed,and the treatment suggestions and subsequent preventive measures were put forward based on the working principle of the oil motor and the control valve anti-jamming logic in the logic of the digital electrohydraulic control system(DEH).Results show that,by strictly controlling the quality of EH oil,optimizing the test process,and enhancing the inspection of logic configurations,the turbine trip caused by ATT can be effectively avoided.The research results have a certain reference significance for the commissioning and operation of similar types of units.
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