SCR denitrification control method based on variable-constraint multi-model prediction control

Abstract

The invention discloses an SCR denitrification control method based on variable-constraint multi-model prediction control. The method is implemented by combining a multi-model prediction control algorithm, an intelligent model weighing algorithm and variable constraint conditions. The method comprises the following steps that 1, a precise NOx prediction model is obtained through the intelligent model weighing algorithm; 2, the optimal real-time ammonia demand is calculated by beans of continuous rolling optimization of the multi-model prediction control algorithm and the constraint conditions changing by following the working conditions. According to the method, the conflict generated between the model precision and the control algorithm when an existing prediction control strategy is applied in an SCR denitrification system is solved; compared with a traditional simple multi-linear-model linear weighing method, the model precision of the algorithm is improved; traditional immobile constraint conditions are changed into the variable constraint conditions changing by following the working conditions, constraint adjustment is more accurate, therefore, the computing burden of a resolution control instruction is reduced, a project is easy to implement, the large lag characteristic of the SCR system is overcome, and the NOx concentration regulation quality is significantly improved.

Description

technical field [0001] The invention relates to thermal power engineering and automatic control, in particular to a thermal power unit SCR denitrification optimization control method based on variable constraint multi-model predictive control technology. Background technique [0002] my country is a big coal country, and the installed weight of thermal power units accounts for about 70%, playing a leading role in the power industry. High-efficiency, energy-saving, and environmentally-friendly thermal power generation technology research is also a top priority related to the development of the national economy. With the increasing environmental problems such as smog, the environmental protection department has put forward higher requirements for the NOx emission standards of thermal power units (50mg / Nm 3 ). The traditional control method of NOx concentration at SCR outlet is PID+feed-forward adjustment method, but the chemical reaction process of SCR denitrification has st...

AI Technical Summary

Problems solved by technology

The published patents in this area have the following two problems: 1. The predictive control algorithm has high requirements on the accuracy of the model used, and the characteristics of the SCR change drastically with the change of the load section

However, due to the complexity of the algorithm and the large amount of calculation, it is difficult to implement it in engineering applications.

Then people use the multi-model switching predictive control algorithm. Although this method reduces the complexity of the algorithm, it uses linear weighting for multiple models when switching models, and the accuracy of the model is limited, which is likely to cause instability in regulation.

2. The scope of constraints is set too broadly

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