CN111396301A - Double-frequency-conversion energy-saving control system and method for circulating water pump of seaside power plant - Google Patents

Double-frequency-conversion energy-saving control system and method for circulating water pump of seaside power plant Download PDF

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CN111396301A
CN111396301A CN202010389504.2A CN202010389504A CN111396301A CN 111396301 A CN111396301 A CN 111396301A CN 202010389504 A CN202010389504 A CN 202010389504A CN 111396301 A CN111396301 A CN 111396301A
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circulating water
water pump
condenser
module
calculating
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王明坤
高林
王林
高海东
侯玉婷
周俊波
郭亦文
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Xian Thermal Power Research Institute Co Ltd
Xian Xire Control Technology Co Ltd
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Thermal Power Research Institute
Xian Xire Control Technology Co Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/06—Control using electricity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
    • F01D25/08—Cooling; Heating; Heat-insulation
    • F01D25/12—Cooling

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  • General Engineering & Computer Science (AREA)
  • Control Of Non-Positive-Displacement Pumps (AREA)

Abstract

The invention discloses a double-frequency-conversion energy-saving control system and method for a circulating water pump of a seaside power plant, which are based on the frequency conversion modification of the circulating water pump, increase the protection control of the pressure of a circulating jellyfish pipe, increase the frequency conversion automatic control of the circulating water pump and a control loop of an outlet valve of the circulating water pump, and arrange the frequency conversion automatic protection control loop of the circulating water pump according to the vacuum of a condenser and the like, thereby realizing the frequency conversion energy-saving automatic control of the circulating water pump, solving the multi-variable cooperative control problems of tide level, circulating water inlet temperature, load and the like, further improving the automatic control level of the power plant, reducing the power consumption of the circulating water pump and realizing.

Description

Double-frequency-conversion energy-saving control system and method for circulating water pump of seaside power plant
Technical Field
The invention relates to the field of automatic control of coal-fired power plants, in particular to a double-frequency-conversion energy-saving control system and method for a circulating water pump of a seaside power plant.
Background
The cold end system of the steam turbine is huge and comprises a condenser, a vacuumizing system, a circulating water system, a condensed water system and the like, so that the problems are more, and the heat economy of the unit is influenced. The normal operation power consumption of each unit auxiliary machine generally accounts for 5% -9% of the generating capacity of the unit, wherein for a seaside power plant, the power consumption of a circulating water pump in a cold end system accounts for a considerable proportion of the plant power consumption. Therefore, the energy-saving and consumption-reducing purposes of the thermal power plant can be effectively realized by the energy-saving and optimized control of the cold end system.
Although the change of the running combination of the circulating pump can be realized by starting and stopping the pump or (and) switching between high and low speeds by using more constant-speed or double-speed circulating water pumps at present, so that the change of the working condition of a cold end is adapted, the starting, stopping and high and low speed switching of a 6kV motor cannot be frequently and continuously carried out, so that the adjustment of limited times can be usually carried out only aiming at long-period seasonal changes, the effective response cannot be carried out on day-night environment temperature difference change, power load peak-valley change and the like, but under the background of deep peak regulation of a thermal power unit, the response to the great change of the latter is more meaningful. The variable-frequency circulating water pump has more free and accurate continuous variable-frequency adjusting capacity, not only can adopt variable-speed control in real time according to the change of working conditions such as load and the like, but also can adopt power frequency operation in a high-load section, and has very wide adaptability, thereby realizing the purposes of energy conservation and consumption reduction under the variable-load working conditions.
On the other hand, the running parameters of cold end equipment such as the running frequency of the circulating water pump are set by depending on manual experience for a plurality of parameters after the frequency conversion transformation of the circulating water pump, and the running combination corresponding to different environmental temperatures and unit loads is given by the conventional cold end optimization technology based on a time-consuming cold end optimization test and by taking running guidance as a technical means. However, due to the limitations of deviation between the actual operation condition and the test condition, scaling of cold end pipelines, difficulty in accurate measurement of unit heat load and circulating water flow, inconvenience in using operation guide tables or curves, high labor intensity of operators and the like, the actual cold end optimization calculation precision is insufficient, the energy-saving effect is limited, and the automatic continuous adjustment capability of the variable-frequency circulating pump cannot be effectively exerted.
Secondly, for a seaside power plant thermal power generating unit which utilizes seawater as a cooling water source of auxiliary machines such as a condenser and the like, on one hand, the temperature difference between day and night and winter and summer is large, and the actual operating environment temperature of the unit often has large fluctuation; on the other hand, the sunlight tide level changes greatly under the influence of the tide, and the tide peak and valley time is indefinite, so that the heat exchange characteristic of the condenser and the power consumption characteristic of the circulating water pump change. And the performance variables influencing the cold end system are more, and the circulating pump parameters cannot be controlled in real time according to the variable changes for operating personnel. Meanwhile, as part of the circulating water of the power plant has multiple purposes, the circulating water can also participate in the cooling of other devices except for ensuring the cooling of the condenser to maintain the vacuum requirement of the condenser, and the pressure of the lowest circulating jellyfish pipe is ensured. Therefore, the independent variables influencing the performance of the cold-end system are many, and the control system and the method are very important. The existing sea side power plant circulating water pump frequency conversion control system does not fully utilize frequency conversion automatic control, the control means still depends on manual input of an operator according to the experience of unit load change and related parameter change, the setting of circulating water pump outlet pressure parameters still lacks scientific guidance, and a large margin is often set for ensuring the unit operation safety, so that the aim of energy conservation cannot be really realized.
At present, the existing circulating water system of the seaside power plant has the technical limitation of frequency conversion energy-saving control:
1. the cold end system of the conventional unit adopts a constant-speed or double-speed circulating water pump, can only adjust for long-period seasonal changes for a limited number of times, and cannot effectively respond to day-night environment temperature difference changes, power load peak-valley changes and the like;
2. for a seaside power plant, due to the multi-variable influences of tide level, day and night/season temperature, load and the like, the heat exchange performance of a condenser and the power consumption of a circulating water pump change at any moment, the relatively accurate control of cold end equipment cannot be finished only by the experience of operators, the controllable parameters of unit start and stop and the like in the actual operation process lack scientific guidance, the parameter setting has blindness, and the power consumption of the circulating pump are serious because the pressure setting allowance of a main pipe of the circulating pump is selected excessively. Meanwhile, when partial load is caused, the circulating water adjusting door participates in action, large throttling loss is caused to the system, and the opening of the circulating water adjusting door is reasonably set.
3. At present, cold end controllable parameters are optimized through partial cold end performance tests, and the cold end controllable parameters comprise frequency conversion parameter setting of a circulating water pump, valve opening degree and the like, wherein performance test data have one-sidedness. On one hand, the sea side power plant is greatly influenced by the change of the tide level, the tide level changes constantly, the running state of the sea side power plant changes in each working condition, and the running characteristics of devices such as a circulating pump, a condenser and the like change, so that the measurement is difficult; secondly, the measurement workload is also a factor to be considered if more comprehensive data is to be obtained under the influence of variables such as tide level, ambient temperature, load and the like. Meanwhile, due to the fact that deviation exists between actual operation working conditions and test working conditions caused by cold end pipeline scaling and the like, cold end optimization control is not accurate, and the energy-saving effect is limited.
4. The cold end system parameter setting is carried out according to the performance test, the cold end system parameter setting is often guided in the form of an operation guide table or curve, and an operator needs to carry out optimization work such as interpolation on the current operation working condition, so that the related setting parameters are determined, the use is inconvenient, and the labor intensity of operators is high. Meanwhile, when the variables are more, the parameter correction in real time is not practical.
Disclosure of Invention
In view of the above problems, the invention develops a circulating water pump double-frequency-conversion energy-saving control system for a cold end system of a sea side power plant, increases the protection control of the pressure of a circulating jellyfish pipe based on the frequency conversion transformation of the circulating water pump, increases a circulating water pump frequency conversion automatic control and a circulating water pump outlet valve control loop, and sets a circulating water pump frequency conversion automatic protection control loop according to the condenser vacuum and the like, thereby realizing the frequency conversion energy-saving automatic control of the circulating water pump, solving the multivariable cooperative control problems of the tide level, the circulating water inlet temperature, the load and the like, further improving the automatic control level of the power plant, reducing the power consumption of the circulating water pump, and realizing the purposes of energy.
In order to achieve the purpose, the invention adopts the following technical scheme:
a double-frequency-conversion energy-saving control system for a circulating water pump of a seaside power plant is characterized in that a first circulating water forebay liquid level sensor 17 for measuring a liquid level signal of a first circulating water forebay 4 and a circulating water main pipe pressure sensor 18 for measuring a pressure of a circulating water main pipe are connected with a first circulating water pump lift calculating module 19, the first circulating water pump lift calculating module 19 for calculating the lift and a first circulating water pump rotating speed sensor 16 for measuring the rotating speed of a first circulating water pump 8 are connected with a first circulating water pump work calculating module 20, and a first circulating water pump current sensor 21 for measuring the current of the first circulating water pump 8 and a first circulating water pump work calculating module 20 are connected with a first circulating water pump characteristic curve correcting module 22; similarly, a second circulating water forebay liquid level sensor 24 for measuring a liquid level signal of a second circulating water forebay 5 and a pressure sensor 18 for measuring a pressure of a circulating jellyfish pipe are connected with a second circulating water pump lift calculation module 25, a second circulating water pump 2 lift calculation module 25 for calculating the lift and a second circulating water pump rotating speed sensor 23 for measuring the rotating speed of a second circulating water pump 9 are connected with a second circulating water pump work calculation module 26, and a second circulating water pump current sensor 27 for measuring the current of the second circulating water pump 9 and a second circulating water pump work calculation module 26 are connected with a second circulating water pump characteristic curve correction module 28; the first circulating water pump lift calculating module 19, the first circulating water pump rotating speed sensor 16, the second circulating water pump lift calculating module 25 and the second circulating water pump rotating speed sensor 23 are connected with a circulating water flow calculating module 31 for calculating the total flow of circulating water; the condenser circulating water inlet temperature sensor 29, the condenser circulating water outlet temperature sensor 30 and the circulating water flow calculating module 31 which are arranged at the inlet and the outlet of the condenser 13 are connected with the condenser heat load calculating module 32; the condenser heat load calculation module 32 is connected with the condenser backpressure calculation module 33, and a condenser vacuum pressure sensor 34 for measuring the actual condenser backpressure, a unit load measurement module 35 for measuring the load of the steam turbine 12, and the condenser backpressure calculation module 33 are connected with the condenser micro-augmentation power curve calculation module 36; the condenser micro-augmentation power curve calculation module 36, the first circulating water pump characteristic curve correction module 22 and the second circulating water pump characteristic curve correction module 28 are connected with the control instruction module 37; the control instruction module 37 is connected with the controlled components of the first circulating water pump 8 and the second circulating water pump 9, and the first condenser circulating water inlet regulating valve 10 and the second condenser circulating water inlet regulating valve 11.
The control method of the double-frequency-conversion energy-saving control system of the circulating water pump of the seaside power plant comprises the following specific steps:
sending a front pool liquid level signal measured by a first circulating water front pool liquid level sensor 17 and a circulating water main pipe pressure signal measured by a circulating water main pipe pressure sensor 18 into a first circulating water pump lift calculation module 19 for calculation, sending the obtained first circulating water pump 8 lift and a first circulating water pump 8 rotating speed signal measured by a first circulating water pump rotating speed sensor 16 into a first circulating water pump work calculation module 20 for interpolation calculation, obtaining a first circulating water pump 8 theoretical pump work according to a circulating pump characteristic curve interpolation provided by a circulating water pump manufacturer, then obtaining a first circulating water pump 8 actual pump work by using a first circulating water pump current signal and a first circulating water pump working voltage calculation, and then sending the first circulating water pump current signal and a first circulating water pump working voltage correction module 22 for correcting a pump work characteristic curve of the first circulating water pump 8; similarly, a front pool liquid level signal measured by a second circulating water front pool liquid level sensor 24 and a circulating water main pipe pressure signal measured by a circulating water main pipe pressure sensor 18 are sent to a second circulating water pump lift calculation module 25 for calculation, the obtained second circulating water pump 9 lift and a second circulating water pump 9 rotating speed signal measured by a second circulating water pump rotating speed sensor 23 are sent to a second circulating water pump work calculation module 26 together for interpolation calculation, theoretical pump work of the second circulating water pump 9 is obtained by interpolation according to a circulating pump characteristic curve provided by a circulating water pump manufacturer, then actual pump work of the second circulating water pump 9 is obtained by calculation by using a second circulating water pump current signal and a second circulating water pump working voltage, and then the actual pump work is sent to a second circulating water pump characteristic curve correction module 28 for correcting the pump work characteristic curve of the second circulating water pump 9; according to the first circulating water pump lift calculating module 19, calculating to obtain the first circulating water pump 8 lift, the first circulating water pump 8 rotating speed signal measured by the first circulating water pump rotating speed sensor 16, calculating to obtain the second circulating water pump 9 lift by the second circulating water pump lift calculating module 25, and the second circulating water pump rotating speed signal measured by the second circulating water pump rotating speed sensor 23, sending the second circulating water pump rotating speed signal into the circulating water flow calculating module 31 for calculation, and inquiring a circulating pump characteristic curve through interpolation to obtain the total circulating water flow; then, the temperatures of the circulating water inlet and the outlet of the condenser are actually measured according to a circulating water inlet temperature sensor 29 of the condenser and a circulating water outlet temperature sensor 30 of the condenser, the total flow of the circulating water is sent to a heat load calculation module 32 of the condenser to calculate the heat load of the condenser, and the heat load is sent to a back pressure calculation module 33 of the condenser to carry out interpolation according to a heat exchange characteristic curve provided by a condenser manufacturer to calculate the theoretical back pressure of the condenser; the actual condenser back pressure measured by combining the condenser vacuum pressure sensor 34 is used for correcting a heat exchange characteristic curve, the steam turbine load measured by the unit load measuring module 35 is sent to the condenser micro-power curve calculating module 36 for calculating the corresponding back pressure-micro-power relationship under different flow rates, and therefore the steam turbine micro-power curve and the pump power consumption characteristic curve are optimized through the control instruction module 37 to obtain the rotating speed instructions of the first circulating pump 8 and the second circulating pump 9 corresponding to the current sea level, the optimal back pressure and the circulating water flow rate and the corresponding opening degrees of the first condenser circulating water inlet regulating valve 10 and the second condenser circulating water inlet regulating valve 11; thereby avoid circulating water flow too big, cause the condenser backpressure that hangs down to cause the waste of circulating water pump power consumption, also can avoid the safety problem that circulating water pump bus pipe pressure hangs down and causes through the regulation of first condenser circulating water inlet damper 10 and second condenser circulating water inlet damper 11.
The method for calculating the corresponding relationship between back pressure and micro power under different flows by the turbine micro power calculation module 36 is as follows:
firstly, a theoretical calculation backpressure p' and an actual measurement backpressure p are obtained through a condenser backpressure calculation module 33 to correct a condenser heat exchange characteristic curve;
Δp＝p-p′
then, when the temperature of circulating water of the condenser is not changed and the heat load is not changed, corresponding back pressure relation curves under different flow rates are given;
p＝f1(Q)+Δp
the formula of the micro-increase power curve is as follows:
Pt＝f2(p)＝f2(f1(Q)+Δp)。
the control instruction module 37 optimizes the turbine micro-power-increasing curve and the pump power consumption characteristic curve by adopting a particle swarm optimization algorithm.
Compared with the prior art, the invention has the following advantages:
1. for a seaside power plant, due to the multi-variable influences of tide level, day and night/season temperature, load and the like, the heat exchange performance of a condenser and the power consumption of a circulating water pump change at any moment, the relatively accurate control of cold end equipment cannot be finished only by the experience of operators, the controllable parameters of unit start and stop and the like in the actual operation process lack scientific guidance, the parameter setting has blindness, and the power consumption of the circulating pump are serious because the pressure setting allowance of a main pipe of the circulating pump is selected excessively. Meanwhile, when partial load is caused, the circulating water regulating valve participates in action, and large throttling loss is caused to the system. By adopting the variable-frequency energy-saving control system, the circulating water flow required under the current tide level, load and ambient temperature can be accurately calculated, so that the maximum opening degree of a circulating water inlet throttle of the condenser is ensured, the throttling loss is effectively reduced, the rotating speed of a circulating water pump is low, and the purposes of energy conservation and emission reduction are achieved.
2. At present, cold end controllable parameters are optimized through partial cold end performance tests, and the cold end controllable parameters comprise frequency conversion parameter setting of a circulating water pump, valve opening degree and the like, wherein performance test data have one-sidedness. On one hand, the sea side power plant is greatly influenced by the change of the tide level, the tide level changes constantly, the running state of the sea side power plant changes in each working condition, and the running characteristics of devices such as a circulating pump, a condenser and the like change, so that the measurement is difficult; secondly, the measurement workload is also a factor to be considered if more comprehensive data is to be obtained under the influence of variables such as tide level, ambient temperature, load and the like. Meanwhile, due to the fact that deviation exists between actual operation working conditions and test working conditions caused by cold end pipeline scaling and the like, cold end optimization control is not accurate, and the energy-saving effect is limited. According to the control method, a real-time and accurate control instruction is obtained by correcting a circulating pump power consumption characteristic curve and a condenser heat exchange characteristic curve through measured data including parameters such as a tidal level, a circulating water inlet temperature, a circulating pump current and a condenser back pressure.
3. The cold end system parameter setting is carried out according to the performance test, the cold end system parameter setting is often guided in the form of an operation guide table or curve, and an operator needs to carry out optimization work such as interpolation on the current operation working condition, so that the related setting parameters are determined, the use is inconvenient, and the labor intensity of operators is high. Meanwhile, when the variables are more, the parameter correction in real time is not practical. The control method adopts self-adaption to analyze the optimal working condition, gives out the optimal control instruction, has continuous instruction, does not need additional operation of operators, and greatly reduces the labor intensity of the operators.
Drawings
FIG. 1 is a schematic diagram of the connection relationship of the system components of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
As shown in a solid line block diagram in fig. 1, the tidal action of seawater 1 of the seaside power plant flows into a first circulating water forebay 4 and a second circulating water forebay 5 after being filtered by a first forebay filter device 2 and a second forebay filter device 3 respectively, an electric valve 6 at an inlet of a first circulating water pump and an electric valve 7 at an inlet of a second circulating water pump are kept fully opened, the seawater is pressurized by a first circulating water pump 8 and a second circulating water pump 9, flows through a circulating water inlet damper 10 of a first condenser and a circulating water inlet damper 11 of a second condenser, and is sent into a condenser 13 to cool the exhaust steam of a steam turbine 12, and then flows out of the condenser and returns to the seawater. On the other side, steam discharged by the steam turbine 12 enters a condenser 13 and is cooled by circulating water and then is sent into a hot well, and then the steam is pressurized by a condensate pump 15 to complete subsequent processes such as heating power generation and the like. The condenser 13 is connected to a vacuum pump 14.
The double-frequency-conversion energy-saving control system of the circulating water pump of the seaside power plant provided by the invention is composed as shown by a dotted line in figure 1:
a first circulating water forebay liquid level sensor 17 for measuring a liquid level signal of the first circulating water forebay 4 and a circulating water main pipe pressure sensor 18 for measuring a pressure of a circulating water main pipe are connected with a first circulating water pump lift calculation module 19, the first circulating water pump lift calculation module 19 for calculating the lift and a first circulating water pump rotating speed sensor 16 for measuring the rotating speed of the first circulating water pump 8 are connected with a first circulating water pump work calculation module 20, and a first circulating water pump current sensor 21 for measuring the current of the first circulating water pump 8 and the first circulating water pump work calculation module 20 are connected with a first circulating water pump characteristic curve correction module 22; similarly, a second circulating water forebay liquid level sensor 24 for measuring a liquid level signal of a second circulating water forebay 5 and a pressure sensor 18 for measuring a pressure of a circulating jellyfish pipe are connected with a second circulating water pump lift calculation module 25, a second circulating water pump 2 lift calculation module 25 for calculating the lift and a second circulating water pump rotating speed sensor 23 for measuring the rotating speed of a second circulating water pump 9 are connected with a second circulating water pump work calculation module 26, and a second circulating water pump current sensor 27 for measuring the current of the second circulating water pump 9 and a second circulating water pump work calculation module 26 are connected with a second circulating water pump characteristic curve correction module 28; the first circulating water pump lift calculating module 19, the first circulating water pump rotating speed sensor 16, the second circulating water pump lift calculating module 25 and the second circulating water pump rotating speed sensor 23 are connected with a circulating water flow calculating module 31 for calculating the total flow of circulating water; the condenser circulating water inlet temperature sensor 29, the condenser circulating water outlet temperature sensor 30 and the circulating water flow calculating module 31 which are arranged at the inlet and the outlet of the condenser 13 are connected with the condenser heat load calculating module 32; the condenser heat load calculation module 32 is connected with the condenser backpressure calculation module 33, and a condenser vacuum pressure sensor 34 for measuring the actual condenser backpressure, a unit load measurement module 35 for measuring the load of the steam turbine 12, and the condenser backpressure calculation module 33 are connected with the condenser micro-augmentation power curve calculation module 36; the condenser micro-augmentation power curve calculation module 36, the first circulating water pump characteristic curve correction module 22 and the second circulating water pump characteristic curve correction module 28 are connected with the control instruction module 37; the control instruction module 37 is connected with the controlled components of the first circulating water pump 8 and the second circulating water pump 9, and the first condenser circulating water inlet regulating valve 10 and the second condenser circulating water inlet regulating valve 11.
The control method based on the technical scheme of the condensed water frequency conversion energy-saving control system comprises the following steps:
sending a front pool liquid level signal measured by a first circulating water front pool liquid level sensor 17 and a circulating water main pipe pressure signal measured by a circulating water main pipe pressure sensor 18 into a first circulating water pump lift calculation module 19 for calculation, sending the obtained first circulating water pump 8 lift and a first circulating water pump 8 rotating speed signal measured by a first circulating water pump rotating speed sensor 16 into a first circulating water pump work calculation module 20 for interpolation calculation, obtaining a first circulating water pump 8 theoretical pump work according to a circulating pump characteristic curve interpolation provided by a circulating water pump manufacturer, then obtaining a first circulating water pump 8 actual pump work by using a first circulating water pump current signal and a first circulating water pump working voltage calculation, and then sending the first circulating water pump current signal and a first circulating water pump working voltage correction module 22 for correcting a pump work characteristic curve of the first circulating water pump 8; similarly, a front pool liquid level signal measured by a second circulating water front pool liquid level sensor 24 and a circulating water main pipe pressure signal measured by a circulating water main pipe pressure sensor 18 are sent to a second circulating water pump lift calculation module 25 for calculation, the obtained second circulating water pump 9 lift and a second circulating water pump 9 rotating speed signal measured by a second circulating water pump rotating speed sensor 23 are sent to a second circulating water pump work calculation module 26 together for interpolation calculation, theoretical pump work of the second circulating water pump 9 is obtained by interpolation according to a circulating pump characteristic curve provided by a circulating water pump manufacturer, then actual pump work of the second circulating water pump 9 is obtained by calculation by using a second circulating water pump current signal and a second circulating water pump working voltage, and then the actual pump work is sent to a second circulating water pump characteristic curve correction module 28 for correcting the pump work characteristic curve of the second circulating water pump 9; according to the first circulating water pump lift calculating module 19, calculating to obtain the first circulating water pump 8 lift, the first circulating water pump 8 rotating speed signal measured by the first circulating water pump rotating speed sensor 16, calculating to obtain the second circulating water pump 9 lift by the second circulating water pump lift calculating module 25, and the second circulating water pump rotating speed signal measured by the second circulating water pump rotating speed sensor 23, sending the second circulating water pump rotating speed signal into the circulating water flow calculating module 31 for calculation, and inquiring a circulating pump characteristic curve through interpolation to obtain the total circulating water flow; then, the temperatures of the circulating water inlet and the outlet of the condenser are actually measured according to a circulating water inlet temperature sensor 29 of the condenser and a circulating water outlet temperature sensor 30 of the condenser, the total flow of the circulating water is sent to a heat load calculation module 32 of the condenser to calculate the heat load of the condenser, and the heat load is sent to a back pressure calculation module 33 of the condenser to carry out interpolation according to a heat exchange characteristic curve provided by a condenser manufacturer to calculate the theoretical back pressure of the condenser; the actual condenser back pressure measured by combining the condenser vacuum pressure sensor 34 is used for correcting a heat exchange characteristic curve, the steam turbine load measured by the unit load measuring module 35 is sent to the condenser micro-power curve calculating module 36 for calculating the corresponding back pressure-micro-power relationship under different flow rates, and therefore the steam turbine micro-power curve and the pump power consumption characteristic curve are optimized through the control instruction module 37 to obtain the rotating speed instructions of the first circulating water pump 8 and the second circulating water pump 9 corresponding to the current sea level, the optimal back pressure and the circulating water flow rate and the corresponding opening degrees of the first condenser circulating water inlet throttle 10 and the second condenser circulating water inlet throttle 11; thereby avoid circulating water flow too big, cause the condenser backpressure that hangs down to cause the waste of circulating water pump power consumption, also can avoid the safety problem that circulating water pump bus pipe pressure hangs down and causes through the regulation of first condenser circulating water inlet damper 10 and second condenser circulating water inlet damper 11.
The calculation process of the relevant modules is described in detail as follows:
(1) the formula for calculating the lift of the circulating water pump by the first circulating water pump lift calculating module 19 and the second circulating water pump lift calculating module 25 is as follows:
Figure BDA0002485258260000111
P1＝ρg(h-Z1)
in the formula: h is the lift/m; p2Is the outlet pressure/Pa of the circulating water pump; p1Is inlet pressure/Pa of a circulating water pump; rho is the average density of inlet and outlet water of the circulating water pump/kg.m-3(ii) a g is the acceleration of gravity (9.81 m.s)-2)；Z2Measuring cross section elevation for circulating water pump outletm；Z1Measuring the section elevation/m for the inlet of the circulating water pump; v2Is the flow velocity/m.s of the outlet pipeline of the circulating water pump-1；V1Is the flow velocity/m.s of the inlet pipeline of the circulating water pump-1(ii) a h is the front pool liquid level/m;
the pipe diameter is the same in the front and back, the flow velocity of the inlet and the outlet is the same, the last item can be omitted, the elevation of the inlet and the outlet is a fixed value, and the inlet pressure of the circulating water pump can be converted by the front pool liquid level and the inlet elevation, so that the circulating jellyfish pipe pressure and the front pool liquid level can be used for input calculation.
(2) The interpolation calculation method of the circulating water flow calculation module 31, the first circulating water pump work calculation module 20 and the second circulating water pump work calculation module 26 is as follows:
the manufacturer provides the characteristic curve and data of the pump, including the relationship between the rotation speed, flow and lift, and the relationship between the rotation speed, flow and pump work. The formula uses the following expression:
Qn＝f(H，n)
Figure BDA0002485258260000121
Figure BDA0002485258260000122
when n is1＜n＜n2When the temperature of the water is higher than the set temperature,
Figure BDA0002485258260000123
Figure BDA0002485258260000124
in the formula: n is the current cycle pump speed/rpm; h is the pump head/m; qnCirculating water flow/m for current rotation speed3·s-1；
Figure BDA0002485258260000125
Is a rotational speed n1Flow rate of circulating water/m3·s-1；
Figure BDA0002485258260000126
Is a rotational speed n2Flow rate of circulating water/m3·s-1；a1、b1、c1、d1And a2、b2、c2、d2Respectively is a circulating water pump at the rotating speed of n1And n2The coefficient of the curve constant of (a);
on the same principle, the pump work is calculated as follows:
Pn＝f(Qn，n)
Figure BDA0002485258260000127
Figure BDA0002485258260000128
when n is1＜n＜n2When the temperature of the water is higher than the set temperature,
Figure BDA0002485258260000129
Figure BDA00024852582600001210
in the formula: n is the current cycle pump speed/rpm; qnCirculating water flow/m for current rotation speed3·s-1；PnThe current rotating speed is the shaft work/W of the pump;
Figure BDA00024852582600001211
is a rotational speed n1The shaft work/W of the pump;
Figure BDA00024852582600001212
is a rotational speed n2The shaft work/W of the pump; a. the1、B1、C1、D1And A2、B2、C2、D2Respectively is a circulating water pump at the rotating speed of n1And n2The coefficient of the curve constant of (a);
(3) the first circulating water pump characteristic curve correcting module 22 and the second circulating water pump characteristic curve correcting module 28 correct the pump work characteristic curve as follows:
theoretical pump shaft work P 'can be obtained by the first circulating water pump work calculation module 20 and the second circulating water pump work calculation module 26'n；
Actual pump input power:
Figure BDA0002485258260000131
the relation between the input power of the pump motor and the work of the pump shaft is as follows: pn＝Pcηηgr
In the formula: u is water pump voltage/kV; i is measured current value/A;
Figure BDA0002485258260000132
power factor, η pump mechanical efficiency, ηgrTo pump motor efficiency;
ΔP＝Pn-P′n
then correcting the curve of the circulating water pump at the current rotating speed by using the deviation;
Pn＝f(Qn，n)+ΔP
then, the corresponding pump shaft work P under different rotating speeds and flows is solved by using the similar theoremn；
Q2/Q1＝n2/n1
P2/P1＝(n2/n1)3
(4) The condenser heat load calculation module 32 performs the condenser heat load according to the following formula:
calculating the heat load: w is MCP(t2-t1)
In the formula: w is the heat load/W of the condenser; cPFor cooling the specific heat capacity at the level of the temperature/J (kg. K)-1(ii) a M is cooling water flow, kg.s-1。
(5) The condenser back pressure calculation module 33 performs the following interpolation calculation:
a manufacturer can provide a condenser heat exchange characteristic curve and data, a relation curve between heat load and back pressure can be obtained when the circulating water flow and the circulating water inlet temperature of the condenser are known, and then the theoretical back pressure can be obtained according to the heat load. The current flow of the circulating water pump is known to be QnThe current condenser circulating water inlet temperature t is calculated according to the following formula:
p＝f(Qn，t，W)
when Q is1＜Qn＜Q2、t1＜t＜t2When the temperature of the water is higher than the set temperature,
Figure BDA0002485258260000141
Figure BDA0002485258260000142
Figure BDA0002485258260000143
Figure BDA0002485258260000144
Figure BDA0002485258260000145
Figure BDA0002485258260000146
Figure BDA0002485258260000147
Figure BDA0002485258260000148
Figure BDA0002485258260000149
Figure BDA00024852582600001410
in the formula: p is the current calculated backpressure/kPa; qnCirculating water flow/m for current rotation speed3·s-1；Q1The characteristic curve is given with the water flow rate/m of the circulation under the working condition 13·s-1；Q2The operating mode 2 circulation water flow/m is given for the characteristic curve3·s-1(ii) a t is the current condenser circulating water inlet temperature/DEG C; t is t1Working condition 1, condenser circulating water inlet temperature/DEG C; t is t2Working condition 2, condenser circulating water inlet temperature/DEG C;
Figure BDA00024852582600001411
is a flow rate of Q1Temperature t1Back pressure/kPa of a lower condenser;
Figure BDA0002485258260000151
is a flow rate of Q1Temperature t2Back pressure/kPa of a lower condenser;
Figure BDA0002485258260000152
is a flow rate of Q2Temperature t1Back pressure/kPa of a lower condenser;
Figure BDA0002485258260000153
is a flow rate of Q2Temperature t2Back pressure/kPa of a lower condenser; a is1、b1、c1、d1And A1、B1、C1、D1Is a flow rate of Q1At a temperature of t1And t2The coefficient of the curve constant of (a); a is2、b2、c2、d2And A2、B2、C2、D2Is a flow rate of Q2At a temperature of t1And t2Coefficient of the curve constant.
(6) The turbine micro-power-increasing calculation module 36 calculates the corresponding relationship between back pressure and micro-power-increasing at different flow rates
Firstly, a theoretical calculation backpressure p' and an actual measurement backpressure p are obtained through a condenser backpressure calculation module 33 to correct a condenser heat exchange characteristic curve.
Δp＝p-p′
Then, when the temperature of circulating water of the condenser is not changed and the heat load is not changed, corresponding back pressure relation curves under different flow rates are given;
p＝f1(Q)+Δp
the formula of the micro-increase power curve is as follows:
Pt＝f2(p)＝f2(f1(Q)+Δp)
(7) the control command module 37 optimizes the turbine micro-power-increasing curve and the pump power consumption characteristic curve by using a particle swarm optimization algorithm, which comprises the following specific steps: (the particle swarm optimization algorithm is a general algorithm)
The first circulating water pump characteristic curve correcting module 22, the second circulating water pump characteristic curve correcting module 28 and the second circulating water pump characteristic curve correcting module 36 can calculate the relation between the corrected flow and the pump power consumption and the slightly increased power, so that the particle swarm algorithm can calculate the flow with the best corresponding benefit among the three, and further calculate the corresponding optimal back pressure, the optimal rotating speed and the valve opening.
Assuming a search in an N-dimensional space, the information of particle i can be represented by two N-dimensional vectors: the position of the ith particle can be represented as xi＝(xi1，xi2，…xiN)TVelocity vi＝(vi1，vi2，…viN)TAfter finding the two optimal solutions, the particle can update its velocity and position according to the following equation:
Figure BDA0002485258260000154
Figure BDA0002485258260000155
in the formula:
Figure BDA0002485258260000161
-the velocity of the particle i in the d-dimension in the k-th iteration;
Figure BDA0002485258260000162
-the current position of the particle i in the d-dimension in the k-th iteration; i-1, 2,3, …, M population size; c. C1、c2-a learning factor; rand1、rand2Is between [0, 1]A random number in between;
Figure BDA0002485258260000163
-the position of particle i at the individual extreme point of dimension d;
Figure BDA0002485258260000164
-the position of the whole population at the global extreme point of dimension d.

Claims (4)

1. The utility model provides a sea side power plant circulating water pump double-conversion energy-saving control system which characterized in that: a first circulating water forebay liquid level sensor (17) for measuring a liquid level signal of a first circulating water forebay (4) and a circulating water main pipe pressure sensor (18) for measuring a pressure of a circulating water main pipe are connected with a first circulating water pump lift calculation module (19), the first circulating water pump lift calculation module (19) for calculating the lift and a first circulating water pump rotating speed sensor (16) for measuring the rotating speed of a first circulating water pump 8 are connected with a first circulating water pump work calculation module (20), and a first circulating water pump current sensor (21) for measuring the current of the first circulating water pump 8 and the first circulating water pump work calculation module (20) are connected with a first circulating water pump characteristic curve correction module (22); similarly, a second circulating water forebay liquid level sensor (24) for measuring a liquid level signal of a second circulating water forebay 5 and a pressure sensor (18) for measuring a pressure of a circulating water main pipe are connected with a second circulating water pump lift calculating module (25), a second circulating water pump 2 lift calculating module (25) for calculating the lift and a second circulating water pump rotating speed sensor (23) for measuring the rotating speed of a second circulating water pump (9) are connected with a second circulating water pump work calculating module (26), and a second circulating water pump current sensor (27) for measuring the current of the second circulating water pump 9 and the second circulating water pump work calculating module (26) are connected with a second circulating water pump characteristic curve correcting module (28); the first circulating water pump lift calculating module (19), the first circulating water pump rotating speed sensor (16), the second circulating water pump lift calculating module (25) and the second circulating water pump rotating speed sensor (23) are connected with a circulating water flow calculating module (31) for calculating the total flow of circulating water; the condenser circulating water inlet temperature sensor (29), the condenser circulating water outlet temperature sensor (30) and the circulating water flow calculation module (31) which are arranged at the inlet and the outlet of the condenser (13) are connected with the condenser heat load calculation module (32); the condenser heat load calculation module (32) is connected with the condenser backpressure calculation module (33), a condenser vacuum pressure sensor (34) for measuring the actual condenser backpressure, a unit load measurement module (35) for measuring the load of the steam turbine (12), and the condenser backpressure calculation module (33) are connected with the condenser micro-power curve calculation module (36); the condenser micro-increase power curve calculation module (36), the first circulating water pump characteristic curve correction module (22) and the second circulating water pump characteristic curve correction module (28) are connected with the control instruction module (37); the control instruction module (37) is connected with a first circulating water pump (8) and a second circulating water pump (9) of controlled components, a first condenser circulating water inlet regulating valve (10) and a second condenser circulating water inlet regulating valve (11).
2. The control method of the double-frequency-conversion energy-saving control system of the circulating water pump of the seaside power plant as claimed in claim 1, is characterized in that: the method comprises the following specific steps:
a front pool liquid level signal measured by a first circulating water front pool liquid level sensor (17) and a circulating water main pipe pressure signal measured by a circulating water main pipe pressure sensor (18) are sent to a first circulating water pump lift calculating module (19) for calculation, the obtained first circulating water pump (8) lift and a first circulating water pump (8) rotating speed signal measured by a first circulating water pump rotating speed sensor (16) are sent to a first circulating water pump work calculating module (20) together for interpolation calculation, obtaining theoretical pumping work of a first circulating water pump (8) by interpolation according to a circulating pump characteristic curve provided by a circulating water pump manufacturer, then calculating to obtain actual pumping work of the first circulating water pump (8) by utilizing a first circulating water pump current signal and a first circulating water pump working voltage, and then sending the actual pumping work to a first circulating water pump characteristic curve correction module (22) to correct the pumping work characteristic curve of the first circulating water pump (8); similarly, a front pool liquid level signal measured by a second circulating water front pool liquid level sensor (24) and a circulating water main pipe pressure signal measured by a circulating water main pipe pressure sensor (18) are sent to a second circulating water pump lift calculation module (25) for calculation, the obtained second circulating water pump (9) lift and a second circulating water pump (9) rotating speed signal measured by a second circulating water pump rotating speed sensor (23) are sent to a second circulating water pump work calculation module (26) together for interpolation calculation, obtaining theoretical pumping work of a second circulating water pump (9) by interpolation according to a circulating pump characteristic curve provided by a circulating water pump manufacturer, then calculating to obtain actual pumping work of the second circulating water pump (9) by utilizing a second circulating water pump current signal and a second circulating water pump working voltage, and then sending the actual pumping work to a second circulating water pump characteristic curve correction module (28) to correct the pumping work characteristic curve of the second circulating water pump (9); according to a first circulating water pump lift calculating module (19), calculating to obtain a first circulating water pump 8) lift, a first circulating water pump (8) rotating speed signal measured by a first circulating water pump rotating speed sensor (16), a second circulating water pump lift calculating module (25) calculating to obtain a second circulating water pump (9) lift, and a second circulating water pump rotating speed signal measured by a second circulating water pump rotating speed sensor (23), sending the second circulating water pump rotating speed signal into a circulating water flow calculating module (31) for calculation, and inquiring a circulating pump characteristic curve through interpolation to obtain the total circulating water flow; then, the temperatures of the inlet and the outlet of circulating water of the condenser are measured according to a circulating water inlet temperature sensor (29) of the condenser and a circulating water outlet temperature sensor (30) of the condenser, the total flow of the circulating water is sent to a heat load calculation module (32) of the condenser to calculate the heat load of the condenser, and the heat load is sent to a back pressure calculation module (33) of the condenser to carry out interpolation according to a heat exchange characteristic curve provided by a condenser manufacturer to calculate the theoretical back pressure of the condenser; the actual condenser backpressure measured by combining a condenser vacuum pressure sensor (34) is used for correcting a heat exchange characteristic curve, the steam turbine load measured by a unit load measuring module (35) is sent to a condenser micro-power curve calculating module (36) for calculating the corresponding backpressure-micro-power relationship under different flow rates, and therefore the steam turbine micro-power curve and the pump power consumption characteristic curve are optimized through a control instruction module (37) to obtain the rotating speed instructions of a first circulating water pump (8) and a second circulating water pump (9) corresponding to the current sea level, the optimal backpressure and the circulating water flow rate and the corresponding opening degrees of a first condenser circulating water inlet throttle (10) and a second condenser circulating water inlet throttle (11); thereby avoid the circulating water flow too big, cause the condenser backpressure that hangs down to cause the waste of circulating water pump power consumption, also can avoid the too low safety problem that causes of circulating water pump mother pipe pressure through the regulation of first condenser circulating water inlet throttle (10) and second condenser circulating water inlet throttle (11).
3. The control method according to claim 2, characterized in that: the method for calculating the corresponding back pressure-micro power relation under different flow rates by the turbine micro power calculation module (36) is as follows:
firstly, a theoretical calculation backpressure p' and an actual measurement backpressure p are obtained through a condenser backpressure calculation module 33 to correct a condenser heat exchange characteristic curve;
Δp＝p-p′
then, when the temperature of circulating water of the condenser is not changed and the heat load is not changed, corresponding back pressure relation curves under different flow rates are given;
p＝f1(Q)+Δp
the formula of the micro-increase power curve is as follows:
Pt＝f2(P)＝f2(f1(Q)+Δp)。
4. the control method according to claim 2, characterized in that: the control instruction module (37) optimizes the steam turbine micro-power-increasing curve and the pump power consumption characteristic curve by adopting a particle swarm optimization algorithm.
CN202010389504.2A 2020-05-10 2020-05-10 Double-frequency-conversion energy-saving control system and method for circulating water pump of seaside power plant Pending CN111396301A (en)

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CN113779898A (en) * 2021-08-16 2021-12-10 中国舰船研究设计中心 Self-flowing circulation design method of small-drift-diameter circulating water system
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CN114087170A (en) * 2021-01-13 2022-02-25 浙江正泰聚能科技有限公司 Control method and control module for frequency of variable-frequency heat pump compressor
CN114087170B (en) * 2021-01-13 2024-01-23 浙江正泰聚能科技有限公司 Control method and control module for frequency of variable-frequency heat pump compressor
CN113107828A (en) * 2021-05-17 2021-07-13 浙江浙能技术研究院有限公司 Energy-saving control strategy applicable to condensate pump of thermal power plant
CN113779898A (en) * 2021-08-16 2021-12-10 中国舰船研究设计中心 Self-flowing circulation design method of small-drift-diameter circulating water system
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CN113806885A (en) * 2021-09-06 2021-12-17 苏州西热节能环保技术有限公司 Turbine cold end optimization curve determination method based on seawater direct supply condenser
CN113806885B (en) * 2021-09-06 2023-11-03 苏州西热节能环保技术有限公司 Method for determining optimization curve of cold end of steam turbine based on seawater direct-supply condenser
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