CN212840734U

CN212840734U - Controller and control system for natural gas branching measurement

Info

Publication number: CN212840734U
Application number: CN202020576771.6U
Authority: CN
Inventors: 高正宪; 许弟建; 郭丽霞; 余英; 翁蕾; 郑媛玉; 刘键铭; 李西西
Original assignee: Chongqing University of Science and Technology
Current assignee: Chongqing University of Science and Technology
Priority date: 2020-04-17
Filing date: 2020-04-17
Publication date: 2021-03-30
Anticipated expiration: 2030-04-17

Abstract

The utility model discloses a controller and control system for natural gas separated time measurement relates to natural gas controlgear technical field, and the concrete scheme is: including separated time counter, treater, control valve and pressure sensor, the separated time counter includes the flowmeter that at least two sets of range ranges are different, flowmeter, control valve and pressure sensor all with treater signal connection, the gas pipeline is equipped with two at least parallelly connected branch passageways that set up, two branch passageways all are connected with the gas main road, all are equipped with flowmeter, control valve and pressure sensor on every branch passageway, flowmeter and control valve quantity and gas branch passageway quantity phase-match. The utility model provides a design and laboratory test work of the hardware design of PLC controller and PLC software system have been accomplished to the controller for the measurement of natural gas separated time. The control principle of the PLC controller is mainly to control the switch of the electromagnetic valve according to the flow measured by branching and to switch in a certain flow range.

Description

Controller and control system for natural gas branching measurement

Technical Field

The utility model relates to a natural gas controlgear technical field, more specifically say, it relates to a controller is used in natural gas separated time measurement.

Background

For a civil gas company, the economic benefit of the company is affected by the difference between the supply and the sales (difference between the supply and the sales) caused by the metering error. Especially, the measuring range of the measuring instrument is large for industrial users, and when the gas consumption is less than the starting flow of the instrument, the measuring leakage is generated, which is extremely unfavorable for company sales. And with the rapid development of local economy and the continuous increase of gas-using enterprises, industrial user customers are more and more, and the supply and sale rate caused by metering becomes one of the main reasons influencing the sales income of gas companies.

Taking Chongqing Yuchuan gas fininshi as an example, the Chongqing Yuchuan gas fininshi is developed into Chongqing gas supplier 'projia' in short 5 years by aiming at industrial and civil gas markets along Chongqing, Hechuan, Nanchuan, Wansheng and Sichuan Dazhou provinces and Yuhe, and the Chongqing gas supplier 'projia' sells natural gas for 100 million cubic meters in every day. However, the difference between supply and sales (difference between supply and sales) caused by the metering error affects the operation of the company for a long time, and affects the economic benefit of the company. Especially, the measuring range of the measuring instrument is large for industrial users, and when the gas consumption is less than the starting flow of the instrument, the measuring leakage is generated, which is extremely unfavorable for company sales. And with the rapid development of the Chongqing economy and the continuous increase of gas-using enterprises, industrial user customers are more and more, and the supply and sale rate caused by metering becomes one of the main reasons influencing the gas sales income of the enterprises. Patent application personnel develop scientific research service and technical cooperation for oil field natural gas companies for a long time and deeply know the importance of the problem of natural gas transmission difference to the natural gas companies. Moreover, investigations have shown that all natural gas companies face the problem of poor transmission to varying degrees.

On the other hand, the natural gas pipe network is designed and installed and operated according to the normal gas use requirement of a user in the design stage, so that the pipeline and the metering instrument are designed and selected according to the normal gas use working condition. When the actual gas consumption is reduced, especially in the case that the gas consumption of some pipeline systems is extremely low in a short time and not long in duration, metering inaccuracy and even meter leakage can be caused. Take Chongqing Yuchuan gas company as an example, the company Long-lived industrial park

At present, 23 industrial users exist in a pipeline, but the section of the pipeline has no total metering, the users are scattered, the pipeline is long, the transmission difference is not easy to control, and the whole metering work management is difficult. The daily gas consumption of the 108 pipelines has larger fluctuation range, the maximum gas consumption per day sometimes reaches 18000 cubes and approaches 20000 cubes, and the maximum gas consumption per day is only hundreds of cubes or even only 100 cubes. In addition, a plurality of potential industrial gas users exist in the long-life industrial park, the gas consumption is expected to be remarkably increased in the future 2-3 years, and the daily gas consumption fluctuation range is expected to be aggravated. The unit gas consumption of each gas of a company is extremely unbalanced, and the gas consumption data from 10 months to 1 month and four months in 2012 to 2013 show that the single daily gas flow rate varies from 0, and the fluctuation is sometimes lower than the starting flow rate of the existing orifice flowmeter, so that the metering is inaccurate or missed.

For natural gas companies, the transmission difference in trade transfer metering will directly affect the economic benefit of the company. The gas supply pipe network and the metering instrument thereof are designed aiming at the working condition of normal gas consumption of users, when the gas consumption of the users drops sharply, the pipe network can surge, the metering of the instrument is inaccurate, and even the meter is missed, so that the sales profits of companies are influenced.

SUMMERY OF THE UTILITY MODEL

For solving the technical problem, the utility model provides a controller is used in measurement of natural gas separated time, the starting flow to present large-traffic user metering instrument is general on the high side, and the defect that the instrument can not the accurate measurement when being less than starting flow with tolerance, for reaching the target of "small flow can measure, large-traffic can the accurate measurement", based on process control theory and flow simulation technique, innovative combines together split control and separated time measurement, has provided natural gas separated time measurement technique and scheme and has been used for the solution of this problem. The design and technical realization of a natural gas branching metering scheme and a controller lay a foundation for the popularization and application of subsequent natural gas branching metering; the above technical purpose of the present invention can be achieved by the following technical solutions:

the utility model provides a controller is used in natural gas separated time measurement, including separated time counter, the treater, control valve and pressure sensor, the separated time counter includes the flowmeter that at least two sets of range ranges are different, flowmeter, control valve and pressure sensor all with treater signal connection, the gas pipeline is equipped with two at least parallelly connected branch passageways that set up, two branch passageways all are connected with the gas main road, all be equipped with flowmeter, control valve and pressure sensor on every branch passageway, flowmeter and control valve quantity and gas branch passageway quantity phase-match.

Preferably, the pressure sensor comprises a pressure transmitter and/or a differential pressure transmitter.

As a preferred scheme, the processor is a PLC control system, and the PLC control system comprises a PLC controller, a safety barrier, a lightning arrester and an instrument panel.

As a preferred scheme, the controller for the natural gas branching and metering further comprises a throttling device and a pressure gauge.

As a preferred scheme, the flow meter is a gas roots flow meter, and the model numbers of the gas roots flow meter are PN1.6DNDNDN100, PN1.6DNDN50 and PN1.6DNDN25; the PLC model is Siemens 1215C-S7-1200, and a 6SE7231-4HD32-0XB0 four-way analog input module is added; the throttling device is a high-level valve type orifice throttling device PN1.6DNDNDN100, the control valve is an explosion-proof electromagnetic valve, and the type of the electromagnetic valve can be PN1.6DNDNDN100 or PN1.6DNDN50.

All signals enter a control box on site and a safety grid needs to be installed; the power supply of the control box is 220V; the PLC controller can adopt a split-range control principle to respectively control the actuating mechanisms of the three electromagnetic valves according to different input range values so as to realize metering switching and automatic control; the PLC takes the flow of the natural gas at each branch line measured by the gas Roots flowmeter at the branch line as the control basis, and each flowmeter is output out of the controller by an electric signal, and the PLC control system realizes the measurement switching and the automatic control.

A natural gas branching measurement control system is based on the natural gas branching measurement controller and is characterized by comprising software and hardware, wherein the software comprises a processing unit, at least two monitoring units, a control unit and a display unit; the processing unit is used for processing the signals, the monitoring unit is used for monitoring the natural gas branch passages and sending monitoring information to the processor, the processor sends signals to the control unit, the control unit is used for controlling the on-off of the different natural gas branch passages, and the display unit is used for information interaction between an operator and the microprocessor.

The PLC control system comprises a PLC controller (explosion-proof), configuration software, a safety barrier, a lightning arrester, an instrument panel, a cable from a field instrument to a field control box, a relay, an explosion-proof flexible connecting pipe, a field emergency stop button and the like.

Preferably, the display unit is a display interface based on an HTLM5 gateway.

The software part includes initialization, inputting sampling and filtering, reducing the sampled digital signal to flow value, and controlling the pipeline valve through the comparison of flow.

A control method for natural gas branching measurement is based on the control system for natural gas branching measurement, and is characterized by comprising the following steps:

s1: initializing a system;

s2: any natural gas branch passage is communicated and metered;

s3: and when the natural gas flow reaches the threshold value of the flow meter in the branch passage, switching step by step.

Preferably, 10% of redundancy is reserved in the flow meter in the natural gas branch passage.

As a preferred scheme, when the adjacent range branch paths are switched, the target branch path is firstly opened, and then the original branch path is closed

To sum up, the utility model discloses following beneficial effect has:

the utility model provides a design and laboratory test work of the hardware design of PLC controller and PLC software system have been accomplished to the controller for the measurement of natural gas separated time. The control principle of the PLC controller is mainly to control the switch of the electromagnetic valve according to the flow measured by branching and to switch in a certain flow range. The natural gas metering precision is improved, and the economic benefit is increased for gas enterprises.

The controller for natural gas branching measurement has stable branching control switching, stable branching measurement working condition, stable and normal controller work, low switching frequency and switching stability of more than 95 percent. The daily relative output difference of the branching metering mode is reduced by 50 percent, the average is only-0.382 percent, and the average is improved by about 10 percent on the basis of the precision of the orifice plate flowmeter.

Drawings

Fig. 1 is a design diagram of a skid-mounted process of a controller for natural gas branching metering in a three-wire mode according to an embodiment of the present invention;

fig. 2 is a hardware design diagram of a controller for natural gas branching metering according to an embodiment of the present invention;

fig. 3 is a functional design diagram of a controller for measuring natural gas branching based on HTML5 according to an embodiment of the present invention;

FIG. 4 is a wiring diagram of the analog module of the present invention;

fig. 5 is a skid-mounted process design diagram of a two-wire mode controller for natural gas branching metering according to an embodiment of the present invention;

FIG. 6 is a diagram of an actuator and conduit configuration according to an embodiment of the present invention;

fig. 7 is a block flow diagram of an embodiment of the invention;

fig. 8 is a data transmission diagram according to an embodiment of the present invention.

Detailed Description

This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. "substantially" means within an acceptable error range, and a person skilled in the art can solve the technical problem within a certain error range to substantially achieve the technical effect.

The present invention will be described in further detail with reference to the accompanying drawings, but the present invention is not limited thereto.

Example 1:

the design scheme of split-line measurement skid-mounted natural gas comprises the following steps:

the technological process of the split-line metering skid-mounted design scheme adopts three-split-line metering, and gas flow in three flow ranges is accurately metered by using flowmeters with different ranges, and only one flowmeter works at any time, as shown in figure 1. The natural gas is filtered and then enters three branch flows to be connected in parallel, metering instruments with different measuring ranges are respectively arranged on the branches, and automatic control and metering switching of the three branches are achieved.

When the gas consumption of a user is particularly large, the control valve in front of the flow meter with the extra-large measuring range is opened, and the control valves in front of the two flow meters with the medium and small measuring ranges are required to be closed; when the user uses a small amount of gas, the control valve in front of the micro flow meter is required to be opened and the other two control valves are required to be closed. Thus, the three control valves are automatically switched according to the flow rate, the three flow rate areas are required to be adjusted according to the gas consumption of users, and if remote detection and control are considered, the designed control unit reserves an interface connected with the SCADA system.

When the branch metering control unit switches the metering flow under the action of the control valve, the flowing working condition of natural gas is changed artificially, and the fluctuation of pressure and flow is inevitably caused, and the fluctuation has great influence on the metering precision of the metering instrument, and the instrument can be damaged in serious conditions.

The control switching logic:

the branch metering switch is based on the total flow (Q) of the natural gas in each branch measured by the gas Roots flowmeter in each branch_{General assembly}＝Q_Small+Q_In+Q_{Big (a)}) The flow metering signals are all output to the controller as input signals of the controller through electric signals.

The controller settings can be set on the PLC panel according to the specific process (again flow value, here assumed to be Q)_min、Q_max，Q_min<Q_maxThe unit: h is used as the reference value. ). The control logic is as follows: when the downstream user airflow is below Q_minThen, the measurement is switched to a small-caliber pipeline for measurement; when the airflow for downstream users is higher than Q_maxThen, the metering is switched to a large-caliber pipeline for metering; when the air flow of the user is between the air flow and the air flow, the metering is switched to a pipeline with a normal caliber for metering. Meanwhile, considering the two-position control, in order to avoid the frequent switching of the control valve, the set value Q of the control switch is controlled_min、Q_maxEach taking into account a certain percentage of redundancy settings (assuming a, B%, respectively, typically 10%, can also be set in the PLC). If the flow represents the input of the controller, the logic values 0 and 1 represent the potential signals of the controller to the electromagnetic valve actuating mechanism respectively (0 represents the valve closing, and 1 represents the valve opening), and the output is a three-position logic value due to three electromagnetic valves, the corresponding values of the input and the output are listed as follows when the actual controller is designed. That is, the controller output is as shown in table 1, table 1 being the logical output values of the three-wire meter mode controller.

TABLE 1

If the input of the controller is Q and the output is f (Q), the input and output characteristics of the controller are expressed by the following formula:

when the flow is in other ranges, the controller has no output and maintains the inertia thereof, and the controller keeps the original output unchanged at the moment. Only when the flow changes are more significant will the controller output change be caused, effecting a switch. The input and output characteristics show that the controller has better inertia characteristics, only when the input flow rate is continuously increased (decreased), the controller is caused to output, metering branching switching is realized, and when the input flow rate fluctuates in a critical range, the electric valve cannot act, so that frequent switching is avoided.

Considering that a certain time delay exists when the electromagnetic valve actuating mechanism performs actions, in order to avoid the situation that one branch line is closed and the other branch line is not opened so as to cause air supply interruption or instability, in the switching design process of the controller, the branch line is set to be opened first and then closed, and the time interval can be set in the PLC. The optimization setting problem of various parameters of the branching metering device (optimization setting of the doubling time and control of the switching time) on the premise of no surge and no working condition fluctuation is researched, and the theoretical calculation basis is provided for the doubling time and other parameters causing the surge, so that the theoretical basis is provided for a parameter setting module of the skid-mounted branching metering device, and an automatic interactive parameter setting interface based on an LED is realized.

The branching measurement is realized by the hardware design of a controller:

selecting the type of the controller: compared with the PLC of other companies, the Siemens PLC has the advantages of small size, high running speed and standard programming, and the latest PLC supports a TCP/IP communication protocol. The practical function is stronger, and is higher than other brands and singlechip reliability, compares in the course that we learned and also simply a lot in other programming. The novel cable connector does not need a large number of wire parts and electronic elements, so that too many cables are not needed, and only the internal input/output ports are needed, so that the fault maintenance is easy, and the corresponding interface points can be quickly found according to the places where faults occur. The method has the characteristics of high program flexibility, simple application, easy programming, convenient troubleshooting and the like, and basically has no problem in operation. And a plurality of programming languages can be selected, and the programming modes are flexible, such as ladder diagrams, statement tables, function table diagrams and the like. Various programming methods make programming simpler, especially ladder diagrams. The ladder diagram is closer to the circuit wiring diagram and is easier to master and understand. Can be understood by common electricians. The PLC of Siemens also has the function of self-diagnosis of faults, and the requirement on the technology of maintenance personnel is greatly reduced. When the system has a fault, maintenance personnel can quickly find the fault part through self diagnosis of hardware and software. In summary, the controller selects the PLC for Siemens.

Since the PLC selecting Siemens needs to select a proper model, the digital quantity input and output and the analog quantity input and output used in the design are not so many, so that the cost is not increased by adopting large and medium-sized PLCs, the small-sized PLCs can be used by selecting the small-sized PLCs, the Siemens small-sized PLCs have two series S7-200 and S7-1200, S7-1200 are series which are newly introduced by Siemens to replace S7-200, the S7-200 PLCs gradually exit the market at present, and various large manufacturing industries also gradually replace S7-200 with S7-1200, and the S7-1200 has the advantages of higher performance, more supported expansion modules, support TCP/IP protocol, Ethernet interface and the like compared with the S7-200, and is closer to the S7-300. Therefore, S7-1200 is selected as the controller, and the CPU model is selected to be 1215C DC/DC/DC,6SE7215-AG40-0XB0, the main parameters of which are shown in Table 2:

supplying power	24VDC,1.5A
		Input point	14
Output point	10
		DI	24VDC,6mA/pt
DQ	24VDC,0.5A/pt
		AI
	2×10BIT,0-10VDC
		AQ
	2×10BIT,0-20mA

TABLE 2

Model selection of an analog quantity module: since 5 analog inputs are required, and the S7-1200PLC itself has only 2 analog inputs, we also need 3 analog inputs. Therefore, an analog input expansion module is needed, because 3 analog input modules are not available, and the least analog input modules are 4 analog input modules, we select 4 analog input modules, and we can select 6SE7231-4HD32-0XB0 four analog input modules to meet the requirements in consideration of economy, and the basic parameters are shown in table 3:

supplying power	24VDC45mA
		Number of analog channels	4-way input
Accuracy of measurement	13bit
		Input signal	0-10VDC

TABLE 3

Hardware design of branching metering controller

During the design switching process of the controller, the controller should be set to be turned on first and then turned off, and the time interval can be set to 10-20 s. Therefore, the situation of two branch lines for parallel metering and air supply can occur in a short time, and the working condition and the air pressure can fluctuate for a short time.

The EM235 is used for detecting the flow of the Roots flowmeter on each branch, and the valve on the pipeline is controlled through the sum of the flow of the branches.

According to the control requirement, the controller of the branch metering adopts PLC control, the number of points of the related switching value is not large in the branch metering process, so that S7-224 AC/DC/RLY of Siemens is adopted, and four paths of analog quantity input are needed for realizing the detection of the bus flowmeter and the detection of 2 paths of branch flow, so that an analog quantity module EM235 is also needed.

The EM235 is the most commonly used analog expansion module, and realizes 4-way analog input and 1-way analog output.

The wiring method of the analog quantity extension module is given in fig. 4, and for the voltage signal, the positive pole and the negative pole are directly connected into the X + and the X-; for the current signal, the RX and the X + are connected into a plus end of the current input signal after being short-circuited; channels not connected to the sensor are shorted to X + and X-. For a certain module, the input end can only be set to one range and format at the same time, namely the same input range and resolution. For the present system, a unipolar current mode input is selected.

In the flow measurement range sequence flow of reducing the sampling data, when the branching control of the flow is carried out, the collected flow is needed to control the branching valve, the analog quantity module of the PLC converts the current signal of 4-20 mA into digital quantity (6400-32000), the flow value corresponding to the digital quantity is related to the quantity value of the flowmeter,

according to a calculation formula of the flowmeter: d refers to the read analog quantity data; am is the maximum measuring range of the flowmeter, and D0 and Dm are two limit values (6400-32000) for converting a 4-20 mA current signal into a digital quantity.

The flow meter in the control system ranges from (2.5 to 800 m)³H) and (0.25-400 m)³/h)

A＝(D－D0)×(Am－A0)/(Dm－D0)+A0。

Flow rate (D-6400) × (Am-a 0)/25600+ a 0.

Because a plurality of flow data need to be converted, the flow conversion is designed into a subprogram for calling by a main program, and the main program only needs to modify the value of (Am-A0) and the value of A0 according to the flow of the flowmeter.

The function design of the controller for branching measurement:

(1) a metering mode: i.e. line switching functionality (three, two or one line);

(2) switching a set value and a redundancy set value thereof;

(3) the switching lag time (doubling time) setting.

Example 2:

single wire metering mode

The single-line measurement adopts normal-caliber pipeline measurement (medium caliber), other two ways are completely closed, and at the moment, other parameter settings are not needed in the PLC panel.

Example 3:

two-line metering mode:

the process for two-line metering is shown in FIG. 5 below. In this mode, the switching setting value and its redundancy, and the doubling time are required to be set. At the moment, a large-caliber pipeline is not arranged, only two pipelines with small caliber and normal caliber are switched to measure, and when the gas consumption is larger than the set maximum flow, two branches are simultaneously opened to measure. The output of the controller is shown in table 4 below, where table 4 is the logical output value of the controller in the two-wire metering mode.

Table 4 the input/output characteristics of the controller in the two-wire mode state are:

the input and output characteristics of the controller in the two-wire mode state are as follows:

the process of the three-wire metering is shown in fig. 1, and the logic output values of the PLC controller are shown in table 1.

Example 4:

controller function for branching measurement based on HTML5 gateway

System function

The design requires that a natural gas three-branch skid-mounted metering control system is designed, an S7-1200PLC is used as a controller, a webpage is used as a monitoring interface of the control system, a WEB gateway is used as a bridge for connecting the PLC and a webpage end, the gateway can also be regarded as a server, a UDP communication protocol is adopted between the PLC and the gateway, and a WebSocket communication protocol is adopted between the gateway and a network terminal, so that data transmission and data reception between the PLC and the webpage terminal are realized by taking the gateway as the bridge. DW software is used for designing a webpage interface, and comprises HTML5 interface design, CSS style attribute design and JavaScript control function design, and BOT software is used for designing a PLC program and comprises a UDP communication protocol and a control function block.

The core of the method is to combine the PLC and the gateway technology, and the accurate measurement of the natural gas of the cross-platform three-way line of the webpage is successfully realized.

Overall system scheme

Software control analysis: the method comprises the steps that large, medium and small flow limits, two sections of redundant quantities and valve closing delay time are sent to a gateway through a WebSocket communication protocol by a webpage, the gateway is sent to a PLC through a UDP communication protocol, the PLC performs logical operation on received data and detected total flow meter flow, then opens corresponding valves, measures accurate flow and accumulated flow, the accumulated flow needs to eliminate the influence of temperature, needs to be operated according to the temperature collected by a temperature sensor, then sends the total flow meter flow, branch accurate flow, valve state and accumulated flow to the gateway through the UDP protocol, the gateway sends the data to the webpage through the WebSocket, the webpage converts the data into the needed data through a series of data processing functions and displays the data, three-branch metering of natural gas is completed, and meanwhile, the field environment can be monitored in real time through a camera.

From the hardware perspective, most of the currently marketed PLCs do not support HTML5 Web configuration programming, HTML5 Web middleware needs to be added into a PLC network, and an HTML5 Web PLC gateway is a hardware middleware developed specially for the PLCs, so that the gateway plays a vital role in data transceiving between the PLCs and Web pages.

Controlling the process flow

According to the requirement of the project, the flow of the total flow meter is detected and fed back to the controller S7-1200PLC, and the large, medium and small flow thresholds, the large, medium and small flow redundancy and the valve shutoff which are set by the webpage are sent to the delay time S7-1200 PLC. And the PLC opens the corresponding valve after mathematical logic operation, and finally the flow of the natural gas is accurately measured through three flow meters of three branch lines. Because the temperature influences the metering accuracy, the metering error caused by the temperature is eliminated by operation by adding temperature acquisition, and finally 5 paths of analog quantity acquisition and 3 digital quantity output exist. Because three valves are controlled by one controller, a split-range control system taking the flow of the total flow meter as feedback is adopted. The process flow chart is as follows:

the control program is mainly based on Siemens S7-1200PLC and is written by Botu software. According to the requirement, the flow size limit is shown in the figure (less than Q)_minTo representSmall flow, greater than Q_minLess than Q_maxHas a medium flow rate of more than Q_maxA large flow rate).

The process logic relationship is: when the initial flow is less than Q_minIf the flow rate rises to the middle flow area and exceeds the dead area A, the middle valve is opened, the small valve is closed after delaying for several seconds, and if the flow rate does not exceed the redundancy A, the small valve is not changed; at the moment, if the flow rate rises to a large flow area and exceeds the redundancy B, the large valve is opened, the small valve is closed after a delay of a few seconds, and if the flow rate does not exceed the redundancy B, the small valve is not changed.

When the initial flow is at Q_minAnd Q_maxIf the flow rate is reduced to a small flow rate area and exceeds the redundancy A, opening the small valve, delaying for several seconds, and closing the middle valve, and if the flow rate does not exceed the redundancy A, keeping the middle valve unchanged; at the moment, if the flow rate rises to a large flow area and exceeds the redundancy B, the large valve is opened, the middle valve is closed after a delay of a few seconds, and if the redundancy B is not exceeded, the middle valve is not changed.

When the initial flow is larger than Q_maxIf the flow rate drops to the middle flow area and exceeds the redundancy B, the middle valve is opened firstly, the large valve is closed after delaying for a few seconds, and if the flow rate does not exceed the redundancy B, the large valve is not changed; at the moment, if the flow rate is reduced to a small flow area and exceeds the redundancy A, the small valve is opened firstly, the large valve is closed after a delay of a few seconds, and if the redundancy is not exceeded, the flow rate is not changed. The flow chart is shown in FIG. 7.

Valve control program implementation

The method comprises the steps of firstly converting the analog quantity IW64 collected by an analog quantity collection port into a flow value of 0-100, storing the flow value into an MB200, then respectively adding and subtracting redundancy quantity into a corresponding M register by using a flow limit, then comparing the current flow with a set value by using Q0.4 as a start button, opening a small valve Q0.0 when the flow MB200 is smaller than a small flow set value MB150, opening a middle valve between the MB150 and the MB151, and opening a large valve when the flow is larger than the MB 151.

When the small valve Q0.0 is opened and the middle valve Q0.1 and the large valve Q0.2 are closed, if the flow rate is increased to the middle flow rate, the Q0.1 is set and the timer T1 is started, and when the timing is up, the Q0.0 is reset to complete the switching from the small valve to the middle valve.

When the middle valve Q0.1 is opened and the small valve Q0.0 and the large valve Q0.2 are closed, if the flow rate is reduced to a small flow rate, the Q0.0 is set and the timer T2 is started, and when the timing is up, the Q0.1 is reset to complete the switching from the middle valve to the small valve.

When the middle valve Q0.1 is opened and the small valve Q0.0 and the large valve Q0.2 are closed, if the flow rate is increased to a large flow rate, the Q0.2 is set and the timer T3 is started, and when the timing is up, the Q0.1 is reset to complete the switching from the middle valve to the large valve.

When the large valve Q0.2 is opened, the small valve Q0.0 and the middle valve Q0.1 are closed, if the flow rate is reduced to the middle flow rate, the Q0.1 is set, the timer T4 is started, and when the timing is up, the Q0.2 is reset to complete the switching from the large valve to the middle valve.

And when the valve is switched to the corresponding position, the corresponding flowmeter is opened to accurately measure the large, medium and small flows, and the flow value is sent to the gateway through the UDP protocol introduced earlier.

Cumulative flow calculation

The flow value per second obtained by dividing the hourly flow value by 3600 is stored in the MW210, the three-line flow MW210 per second is accumulated on the accumulated flow MW212 every second by using the rising edge of the pulse M0.5 of 1 Hz, so that the accumulated flow is obtained, the MW212 is stored in a Temp _1 array and is sent to a gateway by a UDP protocol, and finally, the accumulated flow is displayed on a webpage.

Considering that the temperature can influence the metering of the natural gas, the flow is calculated according to the temperature through temperature detection, when the temperature is too high, the metering data is a little higher than the actual value due to the fact that the density of the natural gas is reduced when the temperature expands with heat and contracts with cold, and when the temperature is higher than 35 ℃, the influence of the too high temperature is eliminated by multiplying a coefficient 1.1; the natural gas density increases when the temperature is too low, which results in lower gauging data, so that the effect of the temperature being too low is eliminated by multiplying the temperature by a factor of 0.9 when the temperature is less than 15 ℃.

The distributed line measurement PLC controller interface function and parameter setting based on HTML5 realize that an HTML5 gateway is the core for connecting a PLC and a webpage terminal, and to finish the communication gateway between the PLC and the webpage, any error can not occur, firstly, a WIFI antenna is connected to a WIFI interface of the gateway, then, the air of a control gateway power supply is turned on and stirred upwards, a short time is waited until the red light of the gateway is bright, at the moment, the gateway is started and finished, then, a mobile phone or a computer is used for turning on the WLAN function, the WIFI can be searched and the situation that a gateway wireless network module is connected is solved.

Parameter setting implementation

And connecting the gateway and the PLC through a network cable, lighting a yellow gateway lamp to indicate that the connection is successful, inputting all the analog quantity of the PLC to an adjustable voltage source on the test bed, and turning on the power supply. At this time, the PLC program designed by graduation is downloaded into the PLC, and simultaneously, the webpage program is downloaded into the gateway, 192.168.1.254:5000 is input by a mobile phone or a computer browser to enter a webpage monitoring field, as shown in FIG. 3.

At this time, Q is_minSet to 30m³/h，Q_max：60m³H, small medium flow dead zone: 3m³H, medium and large flow dead zone: 3m³H, delay time: and 2s, clicking a setting button respectively, and simultaneously monitoring the PLC program to observe that the set value of the webpage is transmitted to the PLC, which shows that the parameter setting is successful and the PLC is successfully communicated with the webpage terminal.

Logic control function implementation

Will Q_min、Q_maxSmall and medium flow dead zone, medium and large flow dead zone, delay time were set to 30m, respectively³/h、60m³/h、3m³/h、3m³/h、1s。

The current flow rate is 27.2m³H is less than the middle and small flow limit Q_min30m³H, so that the small valve is opened and the flow value accurately measured by the small flow meter behind the small valve is 27.27m³H is used as the reference value. The requirement is met, and the logic is proved to have no problem.

When the flow rate rises to 41.5m³At the time of/h, the flow is at the set value Q_minAnd Q_maxSo the medium valve is open and after a 1 second delay the small valve is closed and the medium flow meter shows a flow of 41.59m³H is used as the reference value. The requirement is met, the logic is proved to have no problem, and when the analog input is increased continuously.

At this time, the total valve flow rate was 68.2m³Flow ofThe amount has exceeded Q_maxSo that the middle valve is closed after the large valve is opened, and the flow value of the large flowmeter is 68.13m³H is used as the reference value. In order to prevent the valve from frequently acting, the state of the valve cannot be changed every time the flow value is dead, and the accumulated flow is sequentially increased. The logic completely meets the requirements, and the design of the whole control logic is proved to be correct.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications to the present embodiment without inventive contribution as required after reading the present specification, but all of them are protected by patent laws within the scope of the claims of the present invention.

Claims

1. The utility model provides a controller is used in natural gas separated time measurement, a serial communication port, including the separated time counter, the treater, control valve and pressure sensor, the separated time counter includes the flowmeter that at least two sets of range ranges are different, flowmeter, control valve and pressure sensor all with treater signal connection, the gas pipeline is equipped with two at least parallelly connected branch passageways that set up, two branch passageways all are connected with the gas main road, all be equipped with flowmeter, control valve and pressure sensor on every branch passageway, flowmeter and control valve quantity and gas branch road quantity phase-match.

2. The controller of claim 1, wherein the pressure sensor comprises a pressure transmitter and/or a differential pressure transmitter.

3. The controller for distributing and metering natural gas according to claim 2, wherein the processor is a PLC control system, and the PLC control system comprises a PLC controller, a safety barrier, a lightning arrester and an instrument panel.

4. The controller for natural gas branching and metering of claim 1, further comprising a throttling device and a pressure gauge.

5. The controller for branching and metering natural gas as claimed in claim 1, wherein the flowmeter is a gas roots flowmeter; the PLC model is Siemens 1215C-S7-1200, and a 6SE7231-4HD32-0XB0 four-way analog input module is added; the throttling device is a high-level valve type orifice throttling device PN1.6DNDNDN100, and the control valve is an explosion-proof electromagnetic valve.

6. A natural gas branch metering control system is based on the natural gas branch metering controller of any one of claims 1 to 5, and is characterized by comprising software and the hardware, wherein the software comprises a processing unit, at least two monitoring units, a control unit and a display unit; the processing unit is used for processing the signals, the monitoring unit is used for monitoring the natural gas branch passages and sending monitoring information to the processor, the processor sends signals to the control unit, the control unit is used for controlling the on-off of the different natural gas branch passages, and the display unit is used for information interaction between an operator and the microprocessor.

7. The control system for natural gas distribution metering of claim 6, wherein the display unit is a display interface based on an HTLM5 gateway.