Direct mass balancing and coordinating control system of direct current boiler unit

Abstract

The invention respectively adopts a direct energy balancing mechanism to realize the dynamic decoupling between a steam turbine power regulating loop and a boiler burning regulating loop and a direct mass (flow) balancing mechanism to realize the dynamic decoupling between a steam turbine power regulating loop and a boiler water supply regulating loop, and decouples a usual direct current boiler unit 3*n multi-variable parallel control system onto a decoupling control loop in a hierarchical control structure. The boiler burning regulating loop cancels an usual front side pressure series regulator, and takes the enthalpy increased deviation of an evaporation heated surface of a boiler as the control input; and the boiler water supply regulating loop is designed into fuel-water ratio regulation with a steam turbine power instruction as the input; and the dynamic compensation between boiler burning and water supply is designed. The method best eliminates the coupling impact among all the regulating loops, so that the adjustment is convenient, and the control quality of the direct current furnace unit coordinating control system under the working conditions of variable pressure and variable load is improved.

Description

technical field [0001] The invention relates to a unit unit coordination control system of a thermal power plant, in particular to a unit unit unit coordination control system of a once-through furnace based on a direct energy-mass balance mechanism, belonging to the field of thermal automatic control. Background technique [0002] The controlled object of a thermal power plant unit unit itself is a complex thermal process with nonlinear, multivariable, strong time-varying and large time-delay characteristics. There are strong correlations and strong couplings between variables, especially boiler-turbine power generation Significant differences in dynamic characteristics between machines and strong coupling between variables greatly restrict the load response characteristics of the unit. Therefore, thermal power plant unit units are usually designed with a set of boiler-turbine unit coordinated control system. [0003] By searching the existing literature, it can be found t...

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Problems solved by technology

[0010] In order to overcome the influence of various disturbances and uncertain factors on the adjustment quality of the coordinated control system, in the once-through boiler control strategy provided by some foreign manufacturers, the enthalpy difference signal of the boiler evaporating heating surface is also introduced into the boiler feedwater flow command loop to calculate the fuel-water ratio. However, the structure of its coordinated control system is still the same as that described above (Liu Xiao, Cao Donglin, Ding Jinsong. Design of closed-loop control system for 1000MW ultra-supercritical units in Waigaoqiao[J]. China Electric Power, 2006, 39(3) : 70-73); some domestic studies have also analyzed the heat signal problem of ultra-supercritical units, trying to apply the design idea of ​​DEB direct energy balance coordination control system similar to drum boiler unit units to improve the coordination control system of once-through boiler unit units (Sun Qunli , Li Jiachuan, Wang Zhao, Ma Yumiao. Research on heat signal structure of ultra-supercritical units[J]. Thermal Power Generation, 2009, 38(9): 37-39), but did not give a complete control that can be applied in engineering Program

[0011] Since the energy storage and mass storage of the once-through boiler are much smaller than that of the drum boiler, although the unit unit of the once-through furnace has better load regulation characteristics from the perspective of the thermal system, the change range and rate of the main control parameters are also greater. The operating parameters are high, the safety margin is small, and the advantages and disadvantages of its control characteristics greatly limit the adaptability of the unit to variable loads

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