Secondary valve control method using integral action of PID as manipulated variable demands of primary valve

摘要

According to the present invention, a method for controlling an auxiliary valve in accordance with a required amount of an operation of a main valve by using an integral action of a proportional integral derivative (PID) in a power plant comprises: 1) a step of additionally configuring an auxiliary PID controller (20) for controlling an auxiliary valve (12) in accordance with an output of a main PID controller (10) controlling the main valve (11), allowing a preset positive (+) error to be input into the auxiliary PID controller (20) when the output of the main PID controller (10) is an upper limit value or more, allowing a preset negative (-) error to be input when the output of the main PID controller (10) is a lower limit value or less, and allowing an error of 0 to be input when the output of the main PID controller (10) is between the upper limit value and lower limit value to calculate an error of the auxiliary PID controller (20) in accordance with the output of the main PID controller (10); 2) a step of determining an integral time (Ti) of the auxiliary PID controller (20) according to an opening degree of the auxiliary valve (12); and 3) a step of controlling the auxiliary valve (12) by an output of the auxiliary PID controller (20), which is calculated through equation (1) using as input the error and the integral time (Ti) calculated in steps 1) and 2).