Abstract: During the spray desuperheating control of the main steam temperature of a 300-MW unit, uneven spraying, frequent equipment faults and control failure on temperature disturbance exist, which severely affects the reliability and economy of the unit operation. In order to improve the control level of the main steam temperature, the temperature difference control and the self-adaptation control are applied, integral saturation resistance function and derivative feedforward logic are enhanced and the field equipment is improved. The adoption of these methods results in better spray desuperheating control. The unit operation indicates that the optimization and improvement have reached the expected goal and made the whole unit safer and more efficient.

Key words: thermal generating unit, main steam temperature, spray desuperheating, self-adaptation control, temperature difference control, derivative feedforward