Mechanism research on active power fluctuation caused by steam turbine valve test

To solve the problem of active power fluctuation and oscillation in the process of turbine’s throttle steam valve activity test, the mechanism and solutions were studied based on the real accident data from a thermal power unit. Theoretical analysis on the test control logic, valve actuator and valve flow characteristic was performed, and the results show that the main reason for the power fluctuation is the large deviation between actual valve flow characteristic and the designed one in the process of turbine’s throttle steam valve activity test. Moreover, the unreasonable control logic setting amplified the power fluctuation. After that, the reverse adjustment of primary frequency reset and power closed-loop control intensifies the fluctuation to power oscillation. The static and dynamic experiments both confirm that field test calibration of the valve flow characteristic is an effective way to reduce the active power fluctuation. Meanwhile, optimizing the control logic based on actuator’s characteristic and operation parameters can also relieve or even eliminate the power fluctuation and oscillation.