Ultra-supercritical secondary reheating generator unit reheating steam temperature compound control strategy

Abstract

The invention discloses an ultra-supercritical secondary reheating generator unit reheating steam temperature compound control strategy. The strategy comprises smoke recycling and control over primary and secondary reheater smoke adjusting baffles. The smoke recycling control input is the sum of the primary reheating steam temperature deviation and secondary reheating steam temperature deviation, the output is superposed with the load predication link and the temperature average differentiation link after water spraying, and a smoke recycling command is formed finally. The reheater smoke adjusting baffle control input comes from the difference between the primary reheating steam temperature deviation and secondary reheating steam temperature deviation, the output is superposed with the load predication link and the temperature average differentiation link after water spraying, the primary and secondary reheater side smoke baffles are controlled correspondingly, two control signals and the smoke recycling command are subjected to weighted summing so that disturbance of the smoke recycling adjusting process to the reheating smoke baffles can be eliminated. According to the ultra-supercritical secondary reheating generator unit reheating steam temperature compound control strategy, the smoke recycling rate and adjustment of the reheating smoke baffles are subjected to compound control, and the load predication link is adopted for improving the adjusting quality of the control strategy.

Description

technical field [0001] The invention relates to the technical field of automatic control of thermal power plants, in particular to a composite control strategy for reheating steam temperature of an ultra-supercritical double-reheat generating set. Background technique [0002] In recent years, my country has made remarkable achievements in the field of power generation technology, and power generation technology with supercritical and ultra-supercritical parameter levels has developed rapidly. In 2013, the standard coal consumption of the five major power generation groups was 314.5g / kWh. This achievement is inseparable from the massive operation of large-capacity supercritical and ultra-supercritical units. At present, the technology of an intermediate reheat ultra-supercritical unit is relatively mature, and its parameters are close to the allowable upper limit of existing mature materials, which leads to the inability to continue to improve the cycle efficiency of the uni...

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Problems solved by technology

In terms of structural design, the double reheating unit is much more complicated than the single reheating unit: firstly, after adopting the double reheating operation mode, the convective heat absorption of hot steam increases by about 10%, and the corresponding main steam radiation heat absorption Due to the different thermodynamic mechanisms of radiation heat transfer and convective heat transfer, it will inevitably affect the thermal characteristics of the unit; secondly, an ultra-high pressure cylinder is added to the steam turbine part, a first-stage reheater is added to the boiler side, and the steam-water flow increases. Under the condition of low steam flow rate and relatively long steam-water flow, the dynamic and static response characteristics of the unit will inevitably change greatly; thirdly, a reheater is added to the boiler side, and the arrangement of the heating surface is more complicated, which makes the temperature adjustment of the main and reheat steam The characteristics change greatly, and the dependence on the dynamic and static response characteristics of the unit increases; finally, the temperature of the reheat steam reaches 620°C, which makes the working environment of the metal material on the final stage heating surface worse and more sensitive to the change of the thermal characteristics of the unit

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