Supercritical unit coordination control method based on hierarchical model predictive control algorithm

Abstract

The invention discloses a supercritical unit coordination control method based on a hierarchical model predictive control algorithm. The method comprises the following steps: regarging a controlled object of a supercritical unit as a three-input three-output multivariable system, the input quantity of the system being a water supply flow, a steam turbine control valve opening and an actual coal asfired quantity, and the output quantity being the actual power of the unit, the machine side main steam pressure and the separator outlet temperature; expressing sub-models of different working conditions of the controlled object of the supercritical unit according to a CARIMA model, solving a model prediction value based on a diophantine equation, and finally solving a current optimal control quantity by taking the minimum performance index function as an optimization target; establishing a three-layer sub-model set by adopting a hierarchical structure algorithm; and according to the unit operation load range, the control deviation and the deviation change rate, combining different levels and different numbers of sub-model sets so as to adapt to different control targets during unit operation. The control effect of the supercritical unit can be effectively guaranteed, and the actual engineering requirement is met.

Description

technical field [0001] The invention relates to an automatic control method for thermal energy and power engineering, in particular to a coordinated control method for a supercritical unit based on a layered model predictive control algorithm. Background technique [0002] The current development trend of the power system is low-carbonization. Clean energy, including wind power, photovoltaic power generation, hydropower, and nuclear power, is inherently random and volatile. A large number of grids connected to the grid will inevitably affect the security and stability of the grid. [0003] In order to provide reliable support for the safe operation of the power system, it is still necessary to play the role of thermal power "ballast stone" and continuously improve the flexible operation level of thermal power units. At present, almost all the coordinated control systems of coal-fired power plants are based on PID, and the PID controller is not suitable for the controlled obj...

AI Technical Summary

Problems solved by technology

At present, almost all the coordinated control systems of coal-fired power plants are based on PID, and the PID controller is not suitable for the controlled objects of the coordinated system with large lag, nonlinearity, many constraints and strong coupling when the unit is operating in a wide range of variable loads. As a result, grid-related functions such as unit AGC and primary frequency regulation do not meet the requirements of the grid, which severely restricts the operational flexibility of thermal power units

Although the method of switching sub-models or sub-controllers is easy to implement and has a light computational burden, it is easy to cause jumps in control variables, which is not conducive to system stability; although the method of weighting sub-models or sub-controllers can achieve a smooth transition of the system, the calculation Increased burden

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