Main steam temperature control of ultra supercritical unit based on online identification and IMC-PID

The main steam temperature is an important parameter to affect the economy and security of the generator. Due to the ultra supercritical units of the large capacity and high parameter, the main steam temperature control must be higher quality. However, main steam temperature of ultra supercritical unit has the characteristics of large time delay and different dynamic characteristics in different operating conditions. In the paper, the cascade control structure is applied. And the sampling period is reasonably selected. The identification mutation and the noise effect are inhibited by the threshold δ. The recursive least squares method with forgetting factor is used to identify the dynamic characteristics of main steam temperature on online. According to the IMC-PID theory, internal model control for main steam temperature is realized. Simulation results show that this algorithm is reliable, simple and easy to understand for the application of field personnel. There are less adjustable parameters (just one). In different conditions, the control quality of main steam temperature is improved, and the temperature deviation control is within 3°C.