CN110778918A - Control method and system for steam pipe network balance optimization - Google Patents

Control method and system for steam pipe network balance optimization Download PDF

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Publication number
CN110778918A
CN110778918A CN201911081119.5A CN201911081119A CN110778918A CN 110778918 A CN110778918 A CN 110778918A CN 201911081119 A CN201911081119 A CN 201911081119A CN 110778918 A CN110778918 A CN 110778918A
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pipe network
pressure
control
control loop
output increment
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CN110778918B (en
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程高峰
蒋威
杨振国
胡一智
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Zhejiang Supcon Technology Co Ltd
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Zhejiang Supcon Technology Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17D—PIPE-LINE SYSTEMS; PIPE-LINES
    • F17D1/00—Pipe-line systems
    • F17D1/02—Pipe-line systems for gases or vapours
    • F17D1/06—Pipe-line systems for gases or vapours for steam
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17D—PIPE-LINE SYSTEMS; PIPE-LINES
    • F17D3/00—Arrangements for supervising or controlling working operations
    • F17D3/01—Arrangements for supervising or controlling working operations for controlling, signalling, or supervising the conveyance of a product
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17D—PIPE-LINE SYSTEMS; PIPE-LINES
    • F17D5/00—Protection or supervision of installations
    • F17D5/005—Protection or supervision of installations of gas pipelines, e.g. alarm

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Feedback Control In General (AREA)

Abstract

The invention discloses a control method and a control system for steam pipe network balance optimization, which are applied to single-stage steam pipe networks, wherein each single-stage steam pipe network comprises at least two regulating devices and a discharge device, and the method comprises the following steps: determining the regulating quantity of the corresponding regulating device based on any one of the outlet temperature associated with each regulating device or the first local-level pipe network pressure of the local-level pipe network, the outlet flow associated with each regulating device and the adjacent pipe network pressure of the adjacent pipe network associated with the local-level pipe network; determining the regulating quantity of the relief device based on the second local-level pipe network pressure, the inflow mass flow and the outflow mass flow of the local-level pipe network, which are obtained by the relief device; and adjusting the pipe network pressure of the single-stage steam pipe network to the target pressure together according to the adjustment quantity of all the adjusting devices and the adjustment quantity of the discharge devices, and realizing the automatic control of the balance optimization of the steam pipe network when each single-stage steam pipe network in the whole steam pipe network system adopts the control method.

Description

Control method and system for steam pipe network balance optimization
Technical Field
The invention relates to the technical field of industrial automation control, in particular to a control method and a control system for steam pipe network balance optimization.
Background
In the field of industrial automation control, steam plays an important role as one of power sources. The stable control of the steam pressure is related to the stable operation of the product control process, thereby affecting the production cost of the enterprise.
The steam system bears multiple functions of system heat supply, power driving and the like, a plurality of pipe networks which are used in a pressure gradient mode exist, the steam pipe network of each level bears the driving of equipment of each level, the start and stop or load change of each equipment influences the pressure and the steam consumption of the steam pipe network of the level, and other steam pipe networks which are related to each other are indirectly influenced. The steam devices under each stage of pipe network are connected in series from top to bottom, and the change of the load of any stage of pipe network can affect other pipe networks and devices. From the control requirement, the steam system still can maintain the pressure of the pipe network to a certain extent under the severe disturbance of the change of the working condition, the halt of other equipment is avoided, and the adjusting amplitude and the adjusting time are in a tolerable range. From the production technology, the steam system needs to be capable of realizing automatic control and adjustment according to different load conditions, and the steam demand can be met under various working conditions. From the production cost, the steam control scheme needs to be optimized as much as possible while the safety and stability control is realized and the process production requirements are met, so that the waste is reduced, the energy is saved and the consumption is reduced.
However, in the current domestic complex steam pipe network system, the balance control is mainly controlled by manual scheduling of manpower, so the requirements of system stability, high efficiency and energy conservation can not be met.
Disclosure of Invention
In view of the above, the invention discloses a control method and a control system for steam pipe network balance optimization, so as to realize automatic control on the steam pipe network balance optimization and meet the requirements of system stability, high efficiency and energy conservation.
A control method for balancing and optimizing a steam pipe network is applied to single-stage steam pipe networks, each single-stage steam pipe network comprises at least two adjusting devices and a discharge device, and the steam pipe network system formed by a plurality of single-stage steam pipe networks comprises the following steps:
obtaining an outlet flow associated with each of the regulating devices;
acquiring the outlet temperature associated with each adjusting device or the pressure of the local-level pipe network, and recording the pressure of the local-level pipe network as the first local-level pipe network pressure;
acquiring the adjacent pipe network pressure of the adjacent pipe network associated with the current-stage pipe network;
determining the adjustment quantity of a corresponding adjusting device based on any one of the obtained outlet temperature and the first stage pipe network pressure, the outlet flow and the adjacent pipe network pressure;
acquiring the pressure of the local-level pipe network based on each discharge device, and recording the pressure as the pressure of a second local-level pipe network;
acquiring inflow mass flow and outflow mass flow of the stage of pipe network based on each relief device;
determining the adjustment quantity of the corresponding relief device based on the second stage pipe network pressure, the inflow mass flow and the outflow mass flow;
and jointly adjusting the pipe network pressure of the single-stage steam pipe network to a target pressure according to the adjustment amount of all the adjusting devices and the adjustment amount of the relief device.
Optionally, each of the adjusting devices at least includes three virtual function modules, which are respectively: a first base control loop, a balance control loop, and at least one pressure limit control loop;
the first basic control loop is configured to obtain a control output increment of the first basic control loop based on the outlet temperature of the regulating device or the local stage pipe network pressure as a measured value, the outlet temperature and an outlet temperature set value, or based on the first local stage pipe network pressure and a first local stage pipe network pressure set value;
the balance control loop is used for taking the outlet flow of the adjusting device as a measured value, and obtaining a control output increment of the balance control loop based on the outlet flow and a flow set value;
the pressure limiting control loop is used for judging whether the measured value exceeds a set value of the pressure of the adjacent pipe network by taking the pressure of the adjacent pipe network connected with the current-stage pipe network as the measured value, if so, triggering the pressure limiting function of the pressure limiting control loop, and if not, not triggering the pressure limiting function of the pressure limiting control loop.
Optionally, the determining, based on any one of the obtained outlet temperature and the first local-stage pipe network pressure, the outlet flow and the adjacent pipe network pressure, an adjustment amount of a corresponding adjustment device specifically includes:
determining a control output increment of the first basic control loop based on the outlet temperature and the outlet temperature set value, or based on the stage pipe network pressure and the stage pipe network pressure set value, and recording the control output increment as: a first control output increment;
determining a control output increment for the balance control loop based on the outlet flow and the flow set point as: a second control output increment;
and determining the control output increment of the pressure limit control loop based on the adjacent pipe network pressure of the adjacent pipe network and the set value of the adjacent pipe network pressure, and recording the control output increment as: a third control output increment;
and determining the adjustment amount of the corresponding adjusting device according to the first control output increment, the second control output increment and the third control output increment.
Optionally, the adjustment amount of each of the adjustment devices is determined by control output increments of the first basic control loop, the pressure limit limiting control loop and the balance control loop of the adjustment device, and specifically includes:
when the limiting function of the pressure limiting control circuit is triggered, the adjusting quantity of the adjusting device follows the control output increment of the pressure limiting control circuit, and the control output increments of the first basic control circuit and the balance control circuit are shielded;
when a plurality of pressure limit control loops exist and a limit function is triggered at the same time, selecting the control output increment of the limit control loop with the highest priority as the regulating quantity of the regulating device; when no pressure control circuit triggers the limiting function, the regulating quantity of the regulating device is the control output increment of the first basic control circuit and the control output increment of the balance control circuit;
when the limiting function of the pressure limiting control circuit is not triggered, the regulating quantity of the regulating device is the control output increment of the first basic control circuit and the control output increment of the balance control circuit, and is determined by the fling-cut switch; selecting a control output increment for the first base control loop when the balance control loop is not engaged, or when the balance control loop is engaged and an outlet flow point referenced by the balance control loop fails; when a balance control is engaged, a sum of the control output increment of the balance control loop and the control output increment of the first basic control loop is selected.
Optionally, each of the bleeding devices includes two virtual function modules, which are respectively: a second basic control loop and a flow monitoring unit;
the second basic control loop is used for calculating the control output increment of the second basic control loop by taking the second local-level pipe network pressure as a measured value and based on the second local-level pipe network pressure and a second local-level pipe network pressure set value;
the flow monitoring unit is used for calculating the mass flow difference between inflow mass flow and outflow mass flow of the pipe network and judging whether the mass flow difference is larger than a step control preset value or not, if so, calculating the regulating quantity of the relief device according to the mass flow difference, and taking the regulating quantity of the relief device as a step control quantity; and if not, calculating the variable quantity of the mass flow difference between the inflow and the outflow of the pipe network, and when the variable quantity is larger than a feedforward control preset value, calculating a feedforward quantity according to the variable quantity and transmitting the feedforward quantity to the second basic control loop.
Optionally, the flow monitoring unit is further configured to:
judging whether the pressure of the pipe network of the current stage exceeds a preset pressure value, if so, using a preset step quantity as a step control quantity, wherein the step control quantity can be superposed, and when the pressure of the pipe network of the current stage continuously exceeds the preset pressure value, superposing the preset step control quantity once every time a preset interval time lasts; and if not, calculating the variable quantity of the mass flow difference between the inflow and the outflow of the pipe network, and when the variable quantity is larger than a feedforward control preset value, calculating a feedforward quantity according to the variable quantity and transmitting the feedforward quantity to the second basic control loop.
Optionally, the calculation process of the feedforward quantity is as follows:
calculating the variation of the mass flow difference between inflow and outflow of the pipe networks in two adjacent operation periods according to the following formula;
dw＝ΔQn–ΔQn-1；
in the formula, dw is the variation of the mass flow difference between the inflow and the outflow of the pipe network in two adjacent operation periods, Δ Qn is the mass flow difference between the inflow and the outflow of the pipe network in the current operation period, and Δ Qn-1 is the mass flow difference between the inflow and the outflow of the pipe network in the previous operation period;
calculating a feed forward quantity according to the following formula;
SV＝K*dw/dt；
in the formula, SV is a feedforward quantity, K is a gain coefficient, and dt is a time difference between two adjacent operation periods.
Optionally, the exiting process of the feed forward amount is: and attenuating the feedforward quantity in each operation period according to a preset attenuation time coefficient until the attenuation is zero.
Optionally, the adjustment amount of the relief device is: and the control output increment of the second basic control loop is added to the step control quantity of the flow monitoring unit.
Optionally, the step control amount is calculated by: and calculating the coefficient of the relief device according to the mass flow difference, the front and rear differential pressures of the relief device and the steam density, reversely calculating the regulating quantity of the relief device through the characteristic curve of the relief device, and taking the regulating quantity as a step control quantity.
A control system for balancing and optimizing a steam pipe network, which is applied to single-stage steam pipe networks, wherein each single-stage steam pipe network comprises at least two adjusting devices and a discharge device, and a steam pipe network system formed by a plurality of single-stage steam pipe networks comprises:
a first obtaining unit, configured to obtain an outlet flow rate associated with each of the adjusting devices;
the second obtaining unit is used for obtaining the outlet temperature associated with each regulating device or the pressure of the local-level pipe network, and recording the pressure of the local-level pipe network as the first local-level pipe network pressure;
a third obtaining unit, configured to obtain an adjacent pipe network pressure of an adjacent pipe network associated with the current-stage pipe network;
a first determining unit, configured to determine an adjustment amount of a corresponding adjusting device based on any one of the obtained outlet temperature and the first local-stage pipe network pressure, and the outlet flow and the adjacent pipe network pressure;
the fourth obtaining unit is used for obtaining the pressure of the local-level pipe network based on each discharge device and recording the pressure as the pressure of the second local-level pipe network;
the fifth obtaining unit is used for obtaining inflow mass flow and outflow mass flow of the pipeline network of the stage based on each bleeder device;
the second determining unit is used for determining the regulating quantity of the corresponding relief device based on the second local-stage pipe network pressure, the inflow mass flow and the outflow mass flow;
and the adjusting unit is used for adjusting the pipe network pressure of the single-stage steam pipe network to a target pressure together according to the adjusting amount of all the adjusting devices and the adjusting amount of the discharge device.
Optionally, each of the adjusting devices at least includes three virtual function modules, which are respectively: a first base control loop, a balance control loop, and at least one pressure limit control loop;
the first basic control loop is configured to obtain a control output increment of the first basic control loop based on the outlet temperature of the regulating device or the local stage pipe network pressure as a measured value, the outlet temperature and an outlet temperature set value, or based on the first local stage pipe network pressure and a first local stage pipe network pressure set value;
the balance control loop is used for taking the outlet flow of the adjusting device as a measured value, and obtaining a control output increment of the balance control loop based on the outlet flow and a flow set value;
the pressure limiting control loop is used for judging whether the measured value exceeds a set value of the pressure of the adjacent pipe network by taking the pressure of the adjacent pipe network connected with the current-stage pipe network as the measured value, if so, triggering the pressure limiting function of the pressure limiting control loop, and if not, not triggering the pressure limiting function of the pressure limiting control loop.
Optionally, the first determining unit is specifically configured to:
determining a control output increment of the first basic control loop based on the outlet temperature and the outlet temperature set value, or based on the stage pipe network pressure and the stage pipe network pressure set value, and recording the control output increment as: a first control output increment;
determining a control output increment for the balance control loop based on the outlet flow and the flow set point as: a second control output increment;
and determining the control output increment of the pressure limit control loop based on the adjacent pipe network pressure of the adjacent pipe network and the set value of the adjacent pipe network pressure, and recording the control output increment as: a third control output increment;
and determining the adjustment amount of the corresponding adjusting device according to the first control output increment, the second control output increment and the third control output increment.
Optionally, the adjustment amount of each of the adjustment devices is determined by control output increments of the first basic control loop, the pressure limit limiting control loop and the balance control loop of the adjustment device, and specifically includes:
when the limiting function of the pressure limiting control circuit is triggered, the adjusting quantity of the adjusting device follows the control output increment of the pressure limiting control circuit, and the control output increments of the first basic control circuit and the balance control circuit are shielded;
when a plurality of pressure limit control loops exist and a limit function is triggered at the same time, selecting the control output increment of the limit control loop with the highest priority as the regulating quantity of the regulating device; when no pressure control circuit triggers the limiting function, the regulating quantity of the regulating device is the control output increment of the first basic control circuit and the control output increment of the balance control circuit;
when the limiting function of the pressure limiting control circuit is not triggered, the regulating quantity of the regulating device is the control output increment of the first basic control circuit and the control output increment of the balance control circuit, and is determined by the fling-cut switch; selecting a control output increment for the first base control loop when the balance control loop is not engaged, or when the balance control loop is engaged and an outlet flow point referenced by the balance control loop fails; when a balance control is engaged, a sum of the control output increment of the balance control loop and the control output increment of the first basic control loop is selected.
Optionally, each of the bleeding devices includes two virtual function modules, which are respectively: a second basic control loop and a flow monitoring unit;
the second basic control loop is used for calculating the control output increment of the second basic control loop by taking the second local-level pipe network pressure as a measured value and based on the second local-level pipe network pressure and a second local-level pipe network pressure set value;
the flow monitoring unit is used for calculating the mass flow difference between inflow mass flow and outflow mass flow of the pipe network and judging whether the mass flow difference is larger than a step control preset value or not, if so, calculating the regulating quantity of the relief device according to the mass flow difference, and taking the regulating quantity of the relief device as a step control quantity; and if not, calculating the variable quantity of the mass flow difference between the inflow and the outflow of the pipe network, and when the variable quantity is larger than a feedforward control preset value, calculating a feedforward quantity according to the variable quantity and transmitting the feedforward quantity to the second basic control loop.
Optionally, the flow monitoring unit is further configured to:
judging whether the pressure of the pipe network of the current stage exceeds a preset pressure value, if so, using a preset step quantity as a step control quantity, wherein the step control quantity can be superposed, and when the pressure of the pipe network of the current stage continuously exceeds the preset pressure value, superposing the preset step control quantity once every time a preset interval time lasts; and if not, calculating the variable quantity of the mass flow difference between the inflow and the outflow of the pipe network, and when the variable quantity is larger than a feedforward control preset value, calculating a feedforward quantity according to the variable quantity and transmitting the feedforward quantity to the second basic control loop.
The technical scheme shows that the invention discloses a control method and a system for steam pipe network balance optimization, the method is applied to single-stage steam pipe networks, each single-stage steam pipe network comprises at least two adjusting devices and a discharge device, and the steam pipe network system is composed of a plurality of single-stage steam pipe networks, and the control method comprises the following steps: determining the regulating quantity of the corresponding regulating device based on any one of the outlet temperature associated with each regulating device or the first local-level pipe network pressure of the local-level pipe network, the outlet flow associated with each regulating device and the adjacent pipe network pressure of the adjacent pipe network associated with the local-level pipe network; determining the regulating quantity of the relief device based on the second local-level pipe network pressure, the inflow mass flow and the outflow mass flow of the local-level pipe network, which are obtained by the relief device; and (3) adjusting the pipe network pressure of the single-stage steam pipe network to the target pressure together according to the adjustment quantity of all the adjusting devices and the adjustment quantity of the discharge devices, and realizing the control of the steam pipe network of the whole plant when each single-stage steam pipe network in the whole steam pipe network system adopts the control method disclosed by the invention. Therefore, the invention realizes the automatic control of the balance optimization of the steam pipe network and can meet the requirements of system stability, high efficiency and energy conservation.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the disclosed drawings without creative efforts.
Fig. 1 is a flow chart of a control method for steam pipe network balance optimization disclosed by the embodiment of the invention;
FIG. 2 is a functional logic diagram of a steam pipe network balance optimization disclosed in an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a control system for steam pipe network balance optimization according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention discloses a control method and a control system for steam pipe network balance optimization, the method is applied to single-stage steam pipe networks, each single-stage steam pipe network comprises at least two adjusting devices and a discharge device, and the steam pipe network system formed by a plurality of single-stage steam pipe networks comprises the following steps: determining the regulating quantity of the corresponding regulating device based on any one of the outlet temperature associated with each regulating device or the first local-level pipe network pressure of the local-level pipe network, the outlet flow associated with each regulating device and the adjacent pipe network pressure of the adjacent pipe network associated with the local-level pipe network; determining the regulating quantity of the relief device based on the second local-level pipe network pressure, the inflow mass flow and the outflow mass flow of the local-level pipe network, which are obtained by the relief device; and (3) adjusting the pipe network pressure of the single-stage steam pipe network to the target pressure together according to the adjustment quantity of all the adjusting devices and the adjustment quantity of the discharge devices, and realizing the control of the steam pipe network of the whole plant when each single-stage steam pipe network in the whole steam pipe network system adopts the control method disclosed by the invention. Therefore, the invention realizes the automatic control of the balance optimization of the steam pipe network and can meet the requirements of system stability, high efficiency and energy conservation.
Referring to fig. 1, a flow chart of a control method for steam pipe network balance optimization according to an embodiment of the present invention is applied to a single-stage steam pipe network, each single-stage steam pipe network includes at least two adjusting devices and a discharge device, and a steam pipe network system is composed of a plurality of single-stage steam pipe networks, and the control method includes the steps of:
s101, acquiring outlet flow associated with each adjusting device;
for the purpose of explaining the working principle of the adjusting device, the present invention divides the internal program of the adjusting device into the following components according to the different functions according to the different acquired parameters: three virtual function modules, a first basic control loop, a balancing control loop and a pressure limiting control loop, wherein each regulating device comprises: a first base control loop, a balance control loop, and at least one pressure limit control loop.
Specifically, the first basic control loop of each regulating device is configured to use an outlet temperature of the regulating device or a pipe network pressure of the local pipe network as a measured value, perform pid (proportion integration differentiation) operation on the measured value and a set value, and obtain a control output increment of the first basic control loop based on the outlet temperature and the outlet temperature set value, or based on the first local pipe network pressure and a first local pipe network pressure set value, where the set value of the first basic control loop is derived from a process setting, and the setting basis is related to a pressure or a temperature required by the single-stage steam pipe network during normal production.
And a balance control loop of each regulating device is used for taking the outlet flow of the regulating device as a measured value and calculating the control output increment of the balance control loop based on the measured value and the flow set value.
Wherein the flow set value is derived from the main balance calculation unit.
Specifically, the sampled values of the outlet flow rates of the n regulators are respectively defined as F1, F2, … … Fn, the weights of the n regulators are respectively defined as B1, B2, … … Bn, the main balance calculating unit calculates the SUM of the outlet flow rates of all the regulators as F1+ F2+ … … + Fn, and calculates the set value SVn of the balance control circuit of the nth regulator as SUM + Bn. The nth balance control loop takes the set value SVn as a control target and the outlet flow Fn as a measured value, and the balance control loop calculates the control output increment DMVn of the balance loop of the adjusting device.
Step S102, obtaining outlet temperature associated with each adjusting device or local-level pipe network pressure of a local-level pipe network, and recording the local-level pipe network pressure as first local-level pipe network pressure;
s103, acquiring the pressure of an adjacent pipe network associated with the current-stage pipe network;
and the pressure limiting control loop of each regulating device is used for judging whether the measured value exceeds the set value of the pressure of the adjacent pipe network by taking the pressure of the adjacent pipe network connected with the pipe network of the current stage as the measured value, if so, triggering the pressure limiting function of the pressure limiting control loop, and if not, not triggering the pressure limiting function of the pressure limiting control loop.
The pressure limiting function is mainly applied to safety protection, and when the pressure measurement value of an adjacent pipe network is abnormal in process, for example, the pressure is easy to cause danger when being too high, the adjusting device needs to be forced to increase the opening degree to adjust the pressure relief direction.
Wherein, the setting of the set value of the pressure of the pipe network is derived from the process setting.
It should be noted that the execution sequence of step S101 to step S103 includes, but is not limited to, that shown in fig. 1, and in practical applications, step S101 to step S103 may also be executed simultaneously.
Step S104, determining the regulating quantity of the corresponding regulating device based on any one of the outlet temperature and the first stage pipe network pressure obtained by the regulating device, the outlet flow and the adjacent pipe network pressure;
it should be noted that the adjustment amount of each of the adjusting devices is determined by the control output increments of the first basic control circuit, the pressure limit limiting control circuit, and the balance control circuit of the adjusting device.
Specifically, in this embodiment, step S104 specifically includes:
determining a control output increment of the first basic control loop based on the outlet temperature and the outlet temperature set value, or based on the first local-stage pipe network pressure and the first local-stage pipe network pressure set value, and recording as: a first control output increment;
determining a control output increment for the balance control loop based on the outlet flow and the flow set point as: a second control output increment;
and determining the control output increment of the pressure limit control loop based on the adjacent pipe network pressure of the adjacent pipe network and the set value of the adjacent pipe network pressure, and recording the control output increment as: a third control output increment;
and determining the adjustment amount of the corresponding adjusting device according to the first control output increment, the second control output increment and the third control output increment.
In this embodiment, when there are a plurality of pressure limiting control circuits and the limiting function is simultaneously activated, it is necessary to define the priority and select the control output increment of the limiting control circuit with the highest priority as the adjustment amount of the adjustment device. When no pressure control loop triggers the limiting function, the regulating quantity of the regulating device is the control output increment of the pressure control loop and the control output increment of the balance control loop, and is specifically determined by the fling-cut switch; selecting a control output increment for the first basic control loop when either no balance control is engaged, or balance control is engaged but the outlet flow measurement point for the way referenced by balance control fails; when putting into balance control, the sum of the control output increment of the selected balance control loop and the control output increment of the first basic control loop will be selected.
S105, acquiring the pressure of the local-level pipe network based on each discharge device, and recording the pressure as the second local-level pipe network pressure;
similarly, in order to explain the working principle of the bleeding device, the internal program of the bleeding device is divided into different virtual function modules according to different functions according to different acquired parameters, and the method comprises the following steps: a second basic control loop and a flow monitoring unit, wherein each bleed device comprises: a second basic control loop and a flow monitoring unit.
Specifically, the second basic control loop of each bleeding device is configured to calculate a control output increment of the second basic control loop based on a second local-stage pipe network pressure as a measured value and a second local-stage pipe network pressure set value, where the pipe network pressure set value of the second basic control loop depends on the pressure setting of the process on the pipe network.
In this embodiment, the bleed-off device is used for the sudden change of the pipe network when the functions are more, a set value of the pipe network pressure higher than the pipe network pressure is set in a normal state, and a valve closing action is performed in the normal state through the operation of the basic control loop.
It should be noted that, when the second pipe network pressure set value of the second basic control circuit is higher than the set pressure value of the pipe network of the present stage, the pipe network pressure is lower than the pipe network pressure set value in the normal state, and therefore, the control output increment calculated by the second basic control circuit is in the off direction.
S106, acquiring inflow mass flow and outflow mass flow of the pipe network of the stage based on each relief device;
specifically, the flow monitoring unit of each relief device is configured to calculate a mass flow difference between an inflow mass flow and an outflow mass flow of the pipe network, and determine whether the mass flow difference is greater than a step control preset value, if so, calculate an adjustment amount of the relief device according to the mass flow difference, and use the adjustment amount of the relief device as a step control amount; and if not, calculating the variable quantity of the mass flow difference between the inflow and the outflow of the pipe network, and when the variable quantity is larger than the feedforward control preset value, calculating the feedforward quantity according to the variable quantity of the mass flow difference and transmitting the feedforward quantity to the second basic control loop.
The flow monitoring unit is further configured to:
judging whether the pressure of the pipe network of the current stage exceeds a preset pressure value, if so, using a preset step quantity as a step control quantity, wherein the step control quantity can be superposed, and when the pressure of the pipe network of the current stage continuously exceeds the preset pressure value, superposing the preset step control quantity once every time a preset interval time lasts; and if not, calculating the variable quantity of the mass flow difference between the inflow and the outflow of the pipe network, and when the variable quantity is larger than a feedforward control preset value, calculating a feedforward quantity according to the variable quantity and transmitting the feedforward quantity to the second basic control loop.
The calculation method of the feedforward quantity comprises the following steps:
calculating the variable dw of the mass flow difference between inflow and outflow of the pipe network in two adjacent operation periods according to a formula (1), wherein the formula (1) is as follows:
dw＝ΔQn–ΔQn-1(1)；
in the formula, dw is the variation of the mass flow difference between the inflow and the outflow of the pipe network in two adjacent operation periods, Δ Qn is the mass flow difference between the inflow and the outflow of the pipe network in the current operation period, and Δ Qn-1 is the mass flow difference between the inflow and the outflow of the pipe network in the previous operation period.
The feedforward amount SV is calculated according to the formula (2), and the formula (2) is as follows:
SV＝K*dw/dt(2)；
in the formula, SV is a feedforward quantity, K is a gain coefficient, and dt is a time difference between two adjacent operation periods.
It should be specially noted that a preset dead zone is set in advance for the feedforward quantity, and when the feedforward quantity is smaller than the preset dead zone, the corrected feedforward quantity is zero; and when the feedforward quantity is not less than the preset dead zone, determining that the feedforward quantity is effective.
The feed forward quantity acts as: and transmitting the calculated feedforward quantity to a second basic control loop of the relief device, and superposing the feedforward quantity on a pressure set value of the second basic control loop to form a virtual pressure set value, wherein the virtual pressure set value is lower than a preset pressure set value of the second basic control loop, so that the regulation action of the second basic control loop can be acted in advance.
The exit process of the feed forward amount is: and attenuating the feedforward quantity in each operation period according to a preset attenuation time coefficient until the attenuation is zero.
In practical application, the coefficient of the bleed device may be obtained from the mass flow difference, the differential pressure before and after the bleed device, and the steam density, and the adjustment opening degree of the bleed device may be inversely calculated from the characteristic curve of the bleed device, and the obtained value may be used as the step control amount.
The step control quantity allows for multiple superposition, and the total step control quantity after superposition is used as a superposition item of the regulating quantity of the relief device.
S107, determining the adjustment quantity of a corresponding relief device based on the pipe network pressure of the local-stage pipe network, the inflow mass flow and the outflow mass flow;
specifically, the regulating quantity of the relief device is jointly determined by the second basic control loop of the relief device and the step control quantity of the flow monitoring unit.
The regulating quantity of the relief device is as follows: and the control output increment of the second basic control loop of the relief device is added to the step control quantity of the flow monitoring unit.
And S108, adjusting the pipe network pressure of the single-stage steam pipe network to a target pressure together according to the adjustment amount of all the adjusting devices and the adjustment amount of the relief device.
That is to say, the pipe network pressure of the stage of pipe network is subjected to the combined action of the regulating quantity of all the regulating devices and the regulating quantity of the relief device.
Specifically, after the regulating quantity of the regulating device and the regulating quantity of the discharge device are respectively obtained, the regulating quantities of the regulating device and the discharge device influence the inflow and outflow of steam of the pipe network, so that the pressure of the pipe network is changed, and the pipe network pressure of the single-stage steam pipe network is regulated to the target pressure under the combined action of the regulating device and the discharge device.
It should be particularly noted that the invention realizes the balance optimization control of the pipe network pressure of the single-stage steam pipe network, and when each single-stage steam pipe network in the whole steam pipe network system adopts the control method shown in fig. 1, the steam pipe network control of the whole plant can be realized.
To sum up, the invention discloses a control method for steam pipe network balance optimization, which is applied to single-stage steam pipe networks, each single-stage steam pipe network comprises at least two adjusting devices and a discharge device, and the steam pipe network system is formed by a plurality of single-stage steam pipe networks, and the control method comprises the following steps: determining the regulating quantity of the corresponding regulating device based on any one of the outlet temperature associated with each regulating device or the first local-level pipe network pressure of the local-level pipe network, the outlet flow associated with each regulating device and the adjacent pipe network pressure of the adjacent pipe network associated with the local-level pipe network; determining the regulating quantity of the relief device based on the second local-level pipe network pressure, the inflow mass flow and the outflow mass flow of the local-level pipe network, which are obtained by the relief device; and (3) adjusting the pipe network pressure of the single-stage steam pipe network to the target pressure together according to the adjustment quantity of all the adjusting devices and the adjustment quantity of the discharge devices, and realizing the control of the steam pipe network of the whole plant when each single-stage steam pipe network in the whole steam pipe network system adopts the control method disclosed by the invention. Therefore, the invention realizes the automatic control of the balance optimization of the steam pipe network and can meet the requirements of system stability, high efficiency and energy conservation.
In the above embodiment, the adjusting device determines whether the measured value of the pressure limit control loop, that is, the pressure of the adjacent pipe network connected to the current stage pipe network, exceeds the set value of the pipe network pressure, depending on the direction in which the measured value crosses the set value. If the set value of the pipe network pressure is set to be a high limit value when the process sets the set value of the pipe network pressure, the measured value is a set value crossing the pipe network pressure when the measured value is lower than the set value of the pipe network pressure and higher than the set value of the pipe network pressure, and a limiting function is triggered; if the set value is set to the low limit value by the process, the limiting function is triggered for the crossing pipe network pressure set value when the measured value is greater than the pipe network pressure set value to be smaller than the pipe network pressure set value.
It should be noted that the flow rate set value is set by the main balance calculation unit.
In the above embodiment, the balancing control loop of each regulating device is configured to take the outlet flow of the regulating device as a measured value, and calculate the control output increment of the balancing control loop based on the measured value and a flow set value, and specifically includes:
and counting the total flow of the outlet flows of all the adjusting devices, multiplying the total flow by the weight coefficient of each adjusting device to obtain the target output flow of the adjusting device, transmitting all the target output flows to a balance control loop of the corresponding adjusting device to be used as a loop set value, and calculating a control output increment by the balance control loop.
It should be noted that, when the adjusting function of a certain path of adjusting device fails or manual control is performed or balance control is not performed, the path of adjusting device is removed, and the set value calculation of each path of balance control loop is continued in the remaining effective adjusting devices.
In the above embodiment, the adjusting amount of each adjusting device is determined by the control output increments of the first basic control loop, the pressure limit limiting control loop and the balance control loop of the adjusting device, and specifically includes:
when the limiting function of the pressure limiting control circuit is triggered, the adjusting quantity of the adjusting device follows the control output increment of the pressure limiting control circuit, and the control output increments of the basic control circuit and the balance control circuit are shielded;
when a plurality of pressure limit control loops exist and a limit function is triggered, priority is preset, when the limit function of a high-priority limit control loop is triggered, control output increment of a low-priority limit control loop is shielded, and the adjustment amount of an adjusting device follows the control output increment of the high-priority limit control loop;
when the limiting function of the pressure limiting control loop is not triggered, the regulating quantity of the regulating device is the control output increment of the basic control loop and the control output increment of the balance control loop, and is specifically determined by the fling-cut switch; selecting a control output increment for the base control loop when the balance control loop is not engaged, or when the balance control loop is engaged and an outlet flow point referenced by the balance control loop fails; when a balance control is engaged, the sum of the control output increment of the balance control loop and the control output increment of the base control loop is selected.
In the above embodiment, the flow monitoring unit of the bleed device is configured to calculate the mass flow difference between the inflow mass flow and the outflow mass flow of the pipe network in real time, and determine whether the flow difference is greater than the preset step control value, if so, calculate the adjustment value of the bleed device according to the mass flow difference, and use the adjustment value as the step control value, including:
when the occurrence of step control is detected and the step control quantity is calculated, whether the proportional action is temporarily shielded or not can be selected according to the adjusting effect, and when the step control judging condition is not met, the proportional action of the second basic control loop is recovered;
when the moment of step control is detected, if the second basic control loop of the relief device is in a manual state, the second basic control loop is switched to an automatic state once.
Wherein, the calculation process of the step control quantity is as follows: and calculating the coefficient of the relief device according to the mass flow difference, the front and rear differential pressures of the relief device and the steam density, reversely calculating the regulating quantity of the relief device through the characteristic curve of the relief device, and taking the regulating quantity as a step control quantity. The step control quantity allows multiple times of superposition, and the total step control quantity after superposition is used as a superposed item of the regulating quantity of the relief device.
It is to be noted that, with particular reference to the flow chart shown in fig. 2, each regulating device comprises a first basic control circuit, a balancing control circuit and at least one pressure limiting control circuit, and each relief device comprises a second basic control circuit and a flow monitoring unit.
Corresponding to the embodiment of the method, the invention also discloses a control system for the balance optimization of the steam pipe network.
Referring to fig. 3, a schematic structural diagram of a control system for steam pipe network balance optimization according to an embodiment of the present invention is disclosed, where the control system is applied to a single-stage steam pipe network, each single-stage steam pipe network includes at least two adjusting devices and a bleed device, and a steam pipe network system is composed of a plurality of single-stage steam pipe networks, and the control system includes:
a first obtaining unit 201, configured to obtain an outlet flow rate associated with each of the adjusting devices;
for the purpose of explaining the working principle of the adjusting device, the present invention divides the internal program of the adjusting device into the following components according to the different functions according to the different acquired parameters: three virtual function modules, a first basic control loop, a balancing control loop and a pressure limiting control loop, wherein each regulating device comprises: a first base control loop, a balance control loop, and at least one pressure limit control loop.
Specifically, the first basic control loop of each regulating device is configured to use an outlet temperature of the regulating device or a pipe network pressure of the local pipe network as a measured value, perform pid (proportion integration differentiation) operation on the measured value and a set value, and obtain a control output increment of the first basic control loop based on the outlet temperature and the outlet temperature set value, or based on the first local pipe network pressure and a first local pipe network pressure set value, where the set value of the first basic control loop is derived from a process setting, and the setting basis is related to a pressure or a temperature required by the single-stage steam pipe network during normal production.
And a balance control loop of each regulating device is used for taking the outlet flow of the regulating device as a measured value and calculating the control output increment of the balance control loop based on the measured value and the flow set value.
Wherein the flow set value is derived from the main balance calculation unit.
Specifically, the sampled values of the outlet flow rates of the n regulators are respectively defined as F1, F2, … … Fn, the weights of the n regulators are respectively defined as B1, B2, … … Bn, the main balance calculating unit calculates the SUM of the outlet flow rates of all the regulators as F1+ F2+ … … + Fn, and calculates the set value SVn of the balance control circuit of the nth regulator as SUM + Bn. The nth balance control loop takes the set value SVn as a control target and the outlet flow Fn as a measured value, and the balance control loop calculates the control output increment DMVn of the balance loop of the adjusting device.
A second obtaining unit 202, configured to obtain an outlet temperature associated with each adjusting device or a local-stage pipe network pressure of the local-stage pipe network, and record the local-stage pipe network pressure as a first local-stage pipe network pressure;
a third obtaining unit 203, configured to obtain an adjacent pipe network pressure of an adjacent pipe network associated with the current-stage pipe network;
and the pressure limiting control loop of each regulating device is used for judging whether the measured value exceeds the set value of the pressure of the adjacent pipe network by taking the pressure of the adjacent pipe network connected with the pipe network of the current stage as the measured value, if so, triggering the pressure limiting function of the pressure limiting control loop, and if not, not triggering the pressure limiting function of the pressure limiting control loop.
The pressure limiting function is mainly applied to safety protection, and when the pressure measurement value of an adjacent pipe network is abnormal in process, for example, the pressure is easy to cause danger when being too high, the adjusting device needs to be forced to increase the opening degree to adjust the pressure relief direction.
Wherein, the setting of the set value of the pressure of the pipe network is derived from the process setting.
It should be particularly noted that, the execution sequence of the first acquiring unit 201, the second acquiring unit 202 and the third acquiring unit 203 includes, but is not limited to, the embodiment shown in fig. 3, the execution sequence of the three acquiring units can be adjusted according to actual needs, and the three executing units of the first acquiring unit 201, the second acquiring unit 202 and the third acquiring unit 203 can also be executed simultaneously.
A first determining unit 204, configured to determine an adjustment amount of a corresponding adjusting device based on any one of the obtained outlet temperature and the first local-stage pipe network pressure, and the outlet flow and the adjacent pipe network pressure;
it should be noted that the adjustment amount of each of the adjusting devices is determined by the control output increments of the first basic control circuit, the pressure limit limiting control circuit, and the balance control circuit of the adjusting device.
Specifically, in this embodiment, the first determining unit 204 is specifically configured to:
determining a control output increment of the first basic control loop based on the outlet temperature and the outlet temperature set value, or based on the first local-stage pipe network pressure and the first local-stage pipe network pressure set value, and recording as: a first control output increment;
determining a control output increment for the balance control loop based on the outlet flow and the flow set point as: a second control output increment;
and determining the control output increment of the pressure limit control loop based on the adjacent pipe network pressure of the adjacent pipe network and the set value of the adjacent pipe network pressure, and recording the control output increment as: a third control output increment;
and determining the adjustment amount of the corresponding adjusting device according to the first control output increment, the second control output increment and the third control output increment.
In this embodiment, when there are a plurality of pressure limiting control circuits and the limiting function is simultaneously activated, it is necessary to define the priority and select the control output increment of the limiting control circuit with the highest priority as the adjustment amount of the adjustment device. When no pressure control loop triggers the limiting function, the regulating quantity of the regulating device is the control output increment of the pressure control loop and the control output increment of the balance control loop, and is specifically determined by the fling-cut switch; selecting a control output increment for the first basic control loop when either no balance control is engaged, or balance control is engaged but the outlet flow measurement point for the way referenced by balance control fails; when putting into balance control, the sum of the control output increment of the selected balance control loop and the control output increment of the first basic control loop will be selected.
A fourth obtaining unit 205, configured to obtain, based on each of the bleeding devices, a local pipe network pressure of the local pipe network, which is recorded as a second local pipe network pressure;
similarly, in order to explain the working principle of the bleeding device, the internal program of the bleeding device is divided into different virtual function modules according to different functions according to different acquired parameters, and the method comprises the following steps: a second basic control loop and a flow monitoring unit, wherein each bleed device comprises: a second basic control loop and a flow monitoring unit.
Specifically, the second basic control loop of each bleeding device is configured to calculate a control output increment of the second basic control loop based on a second local-stage pipe network pressure as a measured value and a second local-stage pipe network pressure set value, where the pipe network pressure set value of the second basic control loop depends on the pressure setting of the process on the pipe network.
In this embodiment, the bleed-off device is used for the sudden change of the pipe network when the functions are more, a set value of the pipe network pressure higher than the pipe network pressure is set in a normal state, and a valve closing action is performed in the normal state through the operation of the basic control loop.
It should be noted that, when the second pipe network pressure set value of the second basic control circuit is higher than the set pressure value of the pipe network of the present stage, the pipe network pressure is lower than the pipe network pressure set value in the normal state, and therefore, the control output increment calculated by the second basic control circuit is in the off direction.
A fifth obtaining unit 206, configured to obtain an inflow mass flow and an outflow mass flow of the stage of pipe network based on each of the bleeding devices;
specifically, the flow monitoring unit of each relief device is configured to calculate a mass flow difference between an inflow mass flow and an outflow mass flow of the pipe network, and determine whether the mass flow difference is greater than a step control preset value, if so, calculate an adjustment amount of the relief device according to the mass flow difference, and use the adjustment amount of the relief device as a step control amount; and if not, calculating the variable quantity of the mass flow difference between the inflow and the outflow of the pipe network, and when the variable quantity is larger than the feedforward control preset value, calculating the feedforward quantity according to the variable quantity of the mass flow difference and transmitting the feedforward quantity to the second basic control loop.
The flow monitoring unit is further configured to:
judging whether the pressure of the pipe network of the current stage exceeds a preset pressure value, if so, using a preset step quantity as a step control quantity, wherein the step control quantity can be superposed, and when the pressure of the pipe network of the current stage continuously exceeds the preset pressure value, superposing the preset step control quantity once every time a preset interval time lasts; and if not, calculating the variable quantity of the mass flow difference between the inflow and the outflow of the pipe network, and when the variable quantity is larger than a feedforward control preset value, calculating a feedforward quantity according to the variable quantity and transmitting the feedforward quantity to the second basic control loop.
The calculation method of the feedforward quantity comprises the following steps:
calculating the variable dw of the mass flow difference between inflow and outflow of the pipe network in two adjacent operation periods according to a formula (1), wherein the formula (1) is as follows:
dw＝ΔQn–ΔQn-1(1)；
in the formula, dw is the variation of the mass flow difference between the inflow and the outflow of the pipe network in two adjacent operation periods, Δ Qn is the mass flow difference between the inflow and the outflow of the pipe network in the current operation period, and Δ Qn-1 is the mass flow difference between the inflow and the outflow of the pipe network in the previous operation period.
The feedforward amount SV is calculated according to the formula (2), and the formula (2) is as follows:
SV＝K*dw/dt(2)；
in the formula, SV is a feedforward quantity, K is a gain coefficient, and dt is a time difference between two adjacent operation periods.
It should be specially noted that a preset dead zone is set in advance for the feedforward quantity, and when the feedforward quantity is smaller than the preset dead zone, the corrected feedforward quantity is zero; and when the feedforward quantity is not less than the preset dead zone, determining that the feedforward quantity is effective.
The feed forward quantity acts as: and transmitting the calculated feedforward quantity to a second basic control loop of the relief device, and superposing the feedforward quantity on a pressure set value of the second basic control loop to form a virtual pressure set value, wherein the virtual pressure set value is lower than a preset pressure set value of the second basic control loop, so that the regulation action of the second basic control loop can be acted in advance.
The exit process of the feed forward amount is: and attenuating the feedforward quantity in each operation period according to a preset attenuation time coefficient until the attenuation is zero.
In practical application, the coefficient of the bleed device may be obtained from the mass flow difference, the differential pressure before and after the bleed device, and the steam density, and the adjustment opening degree of the bleed device may be inversely calculated from the characteristic curve of the bleed device, and the obtained value may be used as the step control amount.
The step control quantity allows for multiple superposition, and the total step control quantity after superposition is used as a superposition item of the regulating quantity of the relief device.
A second determining unit 207, configured to determine an adjustment amount of a corresponding bleeding device based on the second local pipe network pressure, the inflow mass flow, and the outflow mass flow;
specifically, the regulating quantity of the relief device is jointly determined by the second basic control loop of the relief device and the step control quantity of the flow monitoring unit.
The regulating quantity of the relief device is as follows: and the control output increment of the second basic control loop of the relief device is added to the step control quantity of the flow monitoring unit.
And the adjusting unit 208 is configured to jointly adjust the pipe network pressure of the single-stage steam pipe network to a target pressure according to the adjustment amount of all the adjusting devices and the adjustment amount of the bleeding device.
That is to say, the pipe network pressure of the stage of pipe network is subjected to the combined action of the regulating quantity of all the regulating devices and the regulating quantity of the relief device.
Specifically, after the regulating quantity of the regulating device and the regulating quantity of the discharge device are respectively obtained, the regulating quantities of the regulating device and the discharge device influence the inflow and outflow of steam of the pipe network, so that the pressure of the pipe network is changed, and the pipe network pressure of the single-stage steam pipe network is regulated to the target pressure under the combined action of the regulating device and the discharge device.
It should be particularly noted that the invention realizes the balance optimization control of the pipe network pressure of the single-stage steam pipe network, and when each single-stage steam pipe network in the whole steam pipe network system adopts the control method shown in fig. 1, the steam pipe network control of the whole plant can be realized.
To sum up, the invention discloses a control system for steam pipe network balance optimization, which is applied to single-stage steam pipe networks, each single-stage steam pipe network comprises at least two adjusting devices and a discharge device, and the steam pipe network system is formed by a plurality of single-stage steam pipe networks, and the control method comprises the following steps: determining the regulating quantity of the corresponding regulating device based on any one of the outlet temperature associated with each regulating device or the first local-level pipe network pressure of the local-level pipe network, the outlet flow associated with each regulating device and the adjacent pipe network pressure of the adjacent pipe network associated with the local-level pipe network; determining the regulating quantity of the relief device based on the second local-level pipe network pressure, the inflow mass flow and the outflow mass flow of the local-level pipe network, which are obtained by the relief device; and (3) adjusting the pipe network pressure of the single-stage steam pipe network to the target pressure together according to the adjustment quantity of all the adjusting devices and the adjustment quantity of the discharge devices, and realizing the control of the steam pipe network of the whole plant when each single-stage steam pipe network in the whole steam pipe network system adopts the control method disclosed by the invention. Therefore, the invention realizes the automatic control of the balance optimization of the steam pipe network and can meet the requirements of system stability, high efficiency and energy conservation.
In the above embodiment, the adjusting device determines whether the measured value of the pressure limit control loop, that is, the pressure of the adjacent pipe network connected to the current stage pipe network, exceeds the set value of the pipe network pressure, depending on the direction in which the measured value crosses the set value. If the set value of the pipe network pressure is set to be a high limit value when the process sets the set value of the pipe network pressure, the measured value is a set value crossing the pipe network pressure when the measured value is lower than the set value of the pipe network pressure and higher than the set value of the pipe network pressure, and a limiting function is triggered; if the set value is set to the low limit value by the process, the limiting function is triggered for the crossing pipe network pressure set value when the measured value is greater than the pipe network pressure set value to be smaller than the pipe network pressure set value.
In the above embodiment, the adjusting amount of each adjusting device is determined by the control output increments of the first basic control loop, the pressure limit limiting control loop and the balance control loop of the adjusting device, and specifically includes:
when the limiting function of the pressure limiting control circuit is triggered, the adjusting quantity of the adjusting device follows the control output increment of the pressure limiting control circuit, and the control output increments of the basic control circuit and the balance control circuit are shielded;
when a plurality of pressure limit control loops exist and a limit function is triggered, priority is preset, when the limit function of a high-priority limit control loop is triggered, control output increment of a low-priority limit control loop is shielded, and the adjustment amount of an adjusting device follows the control output increment of the high-priority limit control loop;
when the limiting function of the pressure limiting control loop is not triggered, the regulating quantity of the regulating device is the control output increment of the basic control loop and the control output increment of the balance control loop, and is specifically determined by the fling-cut switch; selecting a control output increment for the base control loop when the balance control loop is not engaged, or when the balance control loop is engaged and an outlet flow point referenced by the balance control loop fails; when a balance control is engaged, the sum of the control output increment of the balance control loop and the control output increment of the base control loop is selected.
In the above embodiment, the flow monitoring unit of the bleed device is configured to calculate the mass flow difference between the inflow mass flow and the outflow mass flow of the pipe network in real time, and determine whether the flow difference is greater than the preset step control value, if so, calculate the adjustment value of the bleed device according to the mass flow difference, and use the adjustment value as the step control value, including:
when the occurrence of step control is detected and the step control quantity is calculated, whether the proportional action is temporarily shielded or not can be selected according to the adjusting effect, and when the step control judging condition is not met, the proportional action of the second basic control loop is recovered;
when the moment of step control is detected, if the second basic control loop of the relief device is in a manual state, the second basic control loop is switched to an automatic state once.
Wherein, the calculation process of the step control quantity is as follows: and calculating the coefficient of the relief device according to the mass flow difference, the front and rear differential pressures of the relief device and the steam density, reversely calculating the regulating quantity of the relief device through the characteristic curve of the relief device, and taking the regulating quantity as a step control quantity. The step control quantity allows multiple times of superposition, and the total step control quantity after superposition is used as a superposed item of the regulating quantity of the relief device.
Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (16)

1. A control method for balance optimization of a steam pipe network is characterized in that the control method is applied to single-stage steam pipe networks, each single-stage steam pipe network comprises at least two adjusting devices and a discharge device, and a steam pipe network system formed by a plurality of single-stage steam pipe networks comprises the following steps:
obtaining an outlet flow associated with each of the regulating devices;
acquiring the outlet temperature associated with each adjusting device or the pressure of the local-level pipe network, and recording the pressure of the local-level pipe network as the first local-level pipe network pressure;
acquiring the adjacent pipe network pressure of the adjacent pipe network associated with the current-stage pipe network;
determining the adjustment quantity of a corresponding adjusting device based on any one of the obtained outlet temperature and the first stage pipe network pressure, the outlet flow and the adjacent pipe network pressure;
acquiring the pressure of the local-level pipe network based on each discharge device, and recording the pressure as the pressure of a second local-level pipe network;
acquiring inflow mass flow and outflow mass flow of the stage of pipe network based on each relief device;
determining the adjustment quantity of the corresponding relief device based on the second stage pipe network pressure, the inflow mass flow and the outflow mass flow;
and jointly adjusting the pipe network pressure of the single-stage steam pipe network to a target pressure according to the adjustment amount of all the adjusting devices and the adjustment amount of the relief device.
2. Control method according to claim 1, characterized in that each of said regulating devices comprises at least three virtual functional modules, respectively: a first base control loop, a balance control loop, and at least one pressure limit control loop;
the first basic control loop is configured to obtain a control output increment of the first basic control loop based on the outlet temperature of the regulating device or the local stage pipe network pressure as a measured value, the outlet temperature and an outlet temperature set value, or based on the first local stage pipe network pressure and a first local stage pipe network pressure set value;
the balance control loop is used for taking the outlet flow of the adjusting device as a measured value, and obtaining a control output increment of the balance control loop based on the outlet flow and a flow set value;
the pressure limiting control loop is used for judging whether the measured value exceeds a set value of the pressure of the adjacent pipe network by taking the pressure of the adjacent pipe network connected with the current-stage pipe network as the measured value, if so, triggering the pressure limiting function of the pressure limiting control loop, and if not, not triggering the pressure limiting function of the pressure limiting control loop.
3. The control method according to claim 2, wherein the determining an adjustment amount of a corresponding adjustment device based on the obtained any one of the outlet temperature and the first local stage pipe network pressure, the outlet flow rate and the adjacent pipe network pressure specifically includes:
determining a control output increment of the first basic control loop based on the outlet temperature and the outlet temperature set value, or based on the stage pipe network pressure and the stage pipe network pressure set value, and recording the control output increment as: a first control output increment;
determining a control output increment for the balance control loop based on the outlet flow and the flow set point as: a second control output increment;
and determining the control output increment of the pressure limit control loop based on the adjacent pipe network pressure of the adjacent pipe network and the set value of the adjacent pipe network pressure, and recording the control output increment as: a third control output increment;
and determining the adjustment amount of the corresponding adjusting device according to the first control output increment, the second control output increment and the third control output increment.
4. The control method according to claim 3, wherein the adjustment amount of each of the adjusting devices is determined by control output increments of the first basic control circuit, the pressure limit control circuit, and the balance control circuit of the adjusting device, and specifically includes:
when the limiting function of the pressure limiting control circuit is triggered, the adjusting quantity of the adjusting device follows the control output increment of the pressure limiting control circuit, and the control output increments of the first basic control circuit and the balance control circuit are shielded;
when a plurality of pressure limit control loops exist and a limit function is triggered at the same time, selecting the control output increment of the limit control loop with the highest priority as the regulating quantity of the regulating device; when no pressure control circuit triggers the limiting function, the regulating quantity of the regulating device is the control output increment of the first basic control circuit and the control output increment of the balance control circuit;
when the limiting function of the pressure limiting control circuit is not triggered, the regulating quantity of the regulating device is the control output increment of the first basic control circuit and the control output increment of the balance control circuit, and is determined by the fling-cut switch; selecting a control output increment for the first base control loop when the balance control loop is not engaged, or when the balance control loop is engaged and an outlet flow point referenced by the balance control loop fails; when a balance control is engaged, the sum of the control output increment of the balance control loop and the control output increment of the first basic control loop is selected.
5. Control method according to claim 1, characterized in that each of said bleeding devices comprises two virtual function modules, respectively: a second basic control loop and a flow monitoring unit;
the second basic control loop is used for calculating the control output increment of the second basic control loop by taking the second local-level pipe network pressure as a measured value and based on the second local-level pipe network pressure and a second local-level pipe network pressure set value;
the flow monitoring unit is used for calculating the mass flow difference between inflow mass flow and outflow mass flow of the pipe network and judging whether the mass flow difference is larger than a step control preset value or not, if so, calculating the regulating quantity of the relief device according to the mass flow difference, and taking the regulating quantity of the relief device as a step control quantity; and if not, calculating the variable quantity of the mass flow difference between the inflow and the outflow of the pipe network, and when the variable quantity is larger than a feedforward control preset value, calculating a feedforward quantity according to the variable quantity and transmitting the feedforward quantity to the second basic control loop.
6. The control method of claim 5, wherein the flow monitoring unit is further configured to:
judging whether the pressure of the pipe network of the current stage exceeds a preset pressure value, if so, using a preset step quantity as a step control quantity, wherein the step control quantity can be superposed, and when the pressure of the pipe network of the current stage continuously exceeds the preset pressure value, superposing the preset step control quantity once every time a preset interval time lasts; and if not, calculating the variable quantity of the mass flow difference between the inflow and the outflow of the pipe network, and when the variable quantity is larger than a feedforward control preset value, calculating a feedforward quantity according to the variable quantity and transmitting the feedforward quantity to the second basic control loop.
7. The control method according to claim 5, wherein the calculation process of the feedforward amount is:
calculating the variation of the mass flow difference between inflow and outflow of the pipe networks in two adjacent operation periods according to the following formula;
dw＝ΔQn–ΔQn-1；
in the formula, dw is the variation of the mass flow difference between the inflow and the outflow of the pipe network in two adjacent operation periods, Δ Qn is the mass flow difference between the inflow and the outflow of the pipe network in the current operation period, and Δ Qn-1 is the mass flow difference between the inflow and the outflow of the pipe network in the previous operation period;
calculating a feed forward quantity according to the following formula;
SV＝K*dw/dt；
in the formula, SV is a feedforward quantity, K is a gain coefficient, and dt is a time difference between two adjacent operation periods.
8. The control method according to claim 5, characterized in that the exit procedure of the feedforward amount is: and attenuating the feedforward quantity in each operation period according to a preset attenuation time coefficient until the attenuation is zero.
9. The control method of claim 5, wherein the amount of adjustment of the bleed device is: and the control output increment of the second basic control loop is added to the step control quantity of the flow monitoring unit.
10. The control method according to claim 5, characterized in that the step control amount is calculated by: and calculating the coefficient of the relief device according to the mass flow difference, the front and rear differential pressures of the relief device and the steam density, reversely calculating the regulating quantity of the relief device through the characteristic curve of the relief device, and taking the regulating quantity as a step control quantity.
11. A control system for balancing and optimizing a steam pipe network is applied to single-stage steam pipe networks, each single-stage steam pipe network comprises at least two adjusting devices and a discharge device, and a steam pipe network system formed by a plurality of single-stage steam pipe networks comprises:
a first obtaining unit, configured to obtain an outlet flow rate associated with each of the adjusting devices;
the second obtaining unit is used for obtaining the outlet temperature associated with each regulating device or the pressure of the local-level pipe network, and recording the pressure of the local-level pipe network as the first local-level pipe network pressure;
a third obtaining unit, configured to obtain an adjacent pipe network pressure of an adjacent pipe network associated with the current-stage pipe network;
a first determining unit, configured to determine an adjustment amount of a corresponding adjusting device based on any one of the obtained outlet temperature and the first local-stage pipe network pressure, and the outlet flow and the adjacent pipe network pressure;
the fourth obtaining unit is used for obtaining the pressure of the local-level pipe network based on each discharge device and recording the pressure as the pressure of the second local-level pipe network;
the fifth obtaining unit is used for obtaining inflow mass flow and outflow mass flow of the pipeline network of the stage based on each bleeder device;
the second determining unit is used for determining the regulating quantity of the corresponding relief device based on the second local-stage pipe network pressure, the inflow mass flow and the outflow mass flow;
and the adjusting unit is used for adjusting the pipe network pressure of the single-stage steam pipe network to a target pressure together according to the adjusting amount of all the adjusting devices and the adjusting amount of the discharge device.
12. The control system according to claim 11, characterized in that each of said regulating means comprises at least three virtual functional modules, respectively: a first base control loop, a balance control loop, and at least one pressure limit control loop;
the first basic control loop is configured to obtain a control output increment of the first basic control loop based on the outlet temperature of the regulating device or the local stage pipe network pressure as a measured value, the outlet temperature and an outlet temperature set value, or based on the first local stage pipe network pressure and a first local stage pipe network pressure set value;
the balance control loop is used for taking the outlet flow of the adjusting device as a measured value, and obtaining a control output increment of the balance control loop based on the outlet flow and a flow set value;
the pressure limiting control loop is used for judging whether the measured value exceeds a set value of the pressure of the adjacent pipe network by taking the pressure of the adjacent pipe network connected with the current-stage pipe network as the measured value, if so, triggering the pressure limiting function of the pressure limiting control loop, and if not, not triggering the pressure limiting function of the pressure limiting control loop.
13. The control system according to claim 12, wherein the first determination unit is specifically configured to:
determining a control output increment of the first basic control loop based on the outlet temperature and the outlet temperature set value, or based on the stage pipe network pressure and the stage pipe network pressure set value, and recording the control output increment as: a first control output increment;
determining a control output increment for the balance control loop based on the outlet flow and the flow set point as: a second control output increment;
and determining the control output increment of the pressure limit control loop based on the adjacent pipe network pressure of the adjacent pipe network and the set value of the adjacent pipe network pressure, and recording the control output increment as: a third control output increment;
and determining the adjustment amount of the corresponding adjusting device according to the first control output increment, the second control output increment and the third control output increment.
14. The control system of claim 13, wherein the amount of each of the adjustments of the adjustment devices is determined by the control output increments of the first base control loop, the pressure limit control loop, and the balance control loop of the adjustment device, including:
when the limiting function of the pressure limiting control circuit is triggered, the adjusting quantity of the adjusting device follows the control output increment of the pressure limiting control circuit, and the control output increments of the first basic control circuit and the balance control circuit are shielded;
when a plurality of pressure limit control loops exist and a limit function is triggered at the same time, selecting the control output increment of the limit control loop with the highest priority as the regulating quantity of the regulating device; when no pressure control circuit triggers the limiting function, the regulating quantity of the regulating device is the control output increment of the first basic control circuit and the control output increment of the balance control circuit;
when the limiting function of the pressure limiting control circuit is not triggered, the regulating quantity of the regulating device is the control output increment of the first basic control circuit and the control output increment of the balance control circuit, and is determined by the fling-cut switch; selecting a control output increment for the first base control loop when the balance control loop is not engaged, or when the balance control loop is engaged and an outlet flow point referenced by the balance control loop fails; when a balance control is engaged, a sum of the control output increment of the balance control loop and the control output increment of the first basic control loop is selected.
15. Control system according to claim 11, characterized in that each of said bleeding devices comprises two virtual function modules, respectively: a second basic control loop and a flow monitoring unit;
the second basic control loop is used for calculating the control output increment of the second basic control loop by taking the second local-level pipe network pressure as a measured value and based on the second local-level pipe network pressure and a second local-level pipe network pressure set value;
the flow monitoring unit is used for calculating the mass flow difference between inflow mass flow and outflow mass flow of the pipe network and judging whether the mass flow difference is larger than a step control preset value or not, if so, calculating the regulating quantity of the relief device according to the mass flow difference, and taking the regulating quantity of the relief device as a step control quantity; and if not, calculating the variable quantity of the mass flow difference between the inflow and the outflow of the pipe network, and when the variable quantity is larger than a feedforward control preset value, calculating a feedforward quantity according to the variable quantity and transmitting the feedforward quantity to the second basic control loop.
16. The control system of claim 15, wherein the flow monitoring unit is further configured to:
judging whether the pressure of the pipe network of the current stage exceeds a preset pressure value, if so, using a preset step quantity as a step control quantity, wherein the step control quantity can be superposed, and when the pressure of the pipe network of the current stage continuously exceeds the preset pressure value, superposing the preset step control quantity once every time a preset interval time lasts; and if not, calculating the variable quantity of the mass flow difference between the inflow and the outflow of the pipe network, and when the variable quantity is larger than a feedforward control preset value, calculating a feedforward quantity according to the variable quantity and transmitting the feedforward quantity to the second basic control loop.
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