Supercritical unit fuel calorific value correction control method based on dynamic coal-power ratio

Abstract

The invention relates to a supercritical unit fuel calorific value correction control method based on a dynamic power-coal ratio, which comprises the following steps of: calculating a power-coal ratio loop by utilizing a judgment condition of steady-state operation of a unit to obtain a steady-state power-coal ratio coefficient of the unit, and performing product operation on the steady-state power-coal ratio coefficient and a current load instruction to obtain a power-coal ratio coefficient of the unit; obtaining the basic coal quantity of the unit under the condition of the current fire coal heat value; when the unit fire coal heat value changes, correcting the dynamic power-coal ratio of the unit through power-coal ratio correction trigger judgment, single correction coal quantity latching, correction coal quantity superposition and boiler master control reverse compensation of the power-coal ratio correction coal quantity. According to the method, the f(x) function of the coal quantity corresponding to the conventional load is replaced based on the power-coal ratio, so that the accuracy of the coal quantity following the change when the load is changed can be ensured, and meanwhile, the disturbance in the coal calorific value correction process can also be avoided.

Description

technical field [0001] The invention belongs to the technical field of power generation, and in particular relates to a method for correcting and controlling the calorific value of supercritical unit fuels based on a dynamic power-to-coal ratio. Background technique [0002] With the gradual promotion of new energy power generation, the proportion of new energy power generation is increasing year by year, and affected by seasons, sunshine, rainfall and other aspects, the amount of new energy power generation has not yet stabilized. These factors will undoubtedly put forward higher requirements on the peak regulation and frequency regulation capabilities of thermal power units, and at the same time have stricter requirements on the speed and stability of unit load adjustment. With the increase of the operating life of the unit, factors such as equipment aging and failure rate will inevitably increase, all of which will have a greater impact on the safe and stable operation of...

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Problems solved by technology

[0004] The basic coal quantity function f(x) corresponding to the total load of the unit, this function is the relational expression of the coal quantity of the design coal type, when the coal type changes greatly, the characteristics of each auxiliary machine change, the boiler overhaul and other factors occur, this f(x ) function relationship will no longer be accurate, and when the deviation of coal quantity is large, it will cause great disturbance to the correction function of coal calorific value

[0005] Conventional coal-fired calorific value correction (BTU) is based on the comparison of the designed coal volume corresponding to the unit load command with the actual coal volume. When the unit load, pressure, intermediate point temperature, and coal volume are stable, it needs to go through 6000s-8000s of pure integral pid Slowly correct the amount of coal. When the amount of coal changes, the main steam pressure of the unit will change after a period of pure lag time, and the coal amount will be adjusted again through the closed-loop function of the main control of the boiler to achieve the effect of correction. If the correction time is too fast, the coal of the unit will be Large fluctuations in the main steam pressure and main reheat steam temperature; when the correction function is set slowly, although the influence on the main parameters of the unit is slightly weak, the correction function is weak, so that the unit coordination cannot adapt to the change of coal type

At the present stage, due to the impact of faster, larger amplitude and higher frequency of AGC load change, the time for the unit to be in a stable working condition for a long time is shorter, and with the current situation of thermal power units’ urgent demand for fuel, the type of coal entering the plant cannot To meet the requirements of the designed coal type, the calorific value of coal combustion fluctuates greatly, the basic coal amount corresponding to the load in the coordinated control system is no longer an accurate value, and the actual power-to-coal ratio differs greatly from the original design value

Therefore, the conventional coal-fired calorific value correction (BTU) function can no longer meet the coordinated control needs of the units at the present stage, and the coal-fired calorific value cannot be corrected in time, which will cause abnormal over- or under-regulation of the coal volume when the unit load changes. The unit is in an unstable working condition for a long time, which not only affects the safety of the unit, but also is not conducive to the economic operation of the unit

The above-mentioned problems have always been an important factor affecting the quality of the coordinated control system of thermal power units. This invention aims to solve the problem of poor coordinated control of the units under the conditions of frequent changes in fuel species and large calorific value changes, and realize rapid control of the coordinated control system. , Coal quality correction function under zero disturbance

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