WO2020214064A1

WO2020214064A1 - Method and device for the automatic wireless monitoring of a liquid level

Info

Publication number: WO2020214064A1
Application number: PCT/RU2020/000222
Authority: WO
Inventors: Александр Юрьевич ШЕПТОВЕЦКИЙ; Сергей Алексеевич КОРОЛЬКОВ; Филипп Борисович МЕДВЕДЕВ
Original assignee: Общество с ограниченной ответственностью "РадиоТех"
Priority date: 2019-04-16
Filing date: 2020-05-14
Publication date: 2020-10-22
Also published as: RU2722862C1

Abstract

The invention relates to the automatic wireless monitoring of liquid levels and can be used for remotely monitoring liquid levels in bodies of water, on streets, and in rooms, wells, tunnels, reservoirs and other places. The technical result consists in increasing the accuracy and reliability of monitoring and the amount and integrity of information obtained about changes in liquid levels, allowing the timely detection of a change in liquid level, allowing remote automatic monitoring, obviating the need to install wired communication lines, and allowing long-term functioning without the need for technical maintenance. The present device (1) comprises a tube (5) with one open end (6), inside which is mounted a hermetic partition (9), giving rise to two cavities (10, 11) inside the tube. In the first cavity (10) there is mounted a first air pressure sensor (12). In the second cavity (11) there are mounted a second air pressure sensor (13), a radio transmitting device (16), a master controller (15) provided with software and connected to the radio transmitting device (16) and to each of the air pressure sensors (12, 13), and a power supply (14) connected to the master controller (15) and to the radio transmitting device (16). The tube (5) has a through opening (17) in the region between the hermetic partition (9) and the closed end (7).

Description

METHOD AND DEVICE FOR AUTOMATED WIRELESS

CONTROL OF LIQUID LEVEL

The invention relates to radio electronic equipment designed for automated wireless control 5 of the height of the liquid level, and can be used for remote monitoring of the liquid level in reservoirs, on the streets, in rooms, wells, tunnels, reservoirs and other places where it is necessary to control the liquid level with a remote by the way of automatic reading.

10 From the prior art, a non-contact radio wave method for measuring the level of a liquid in a container is known, which consists in the fact that frequency-modulated linear electromagnetic waves are emitted towards the surface of the liquid along the normal to it, reflected 5 electromagnetic waves are received, and the first signal of the difference frequency is isolated at the output the first mixer between the incident and reflected electromagnetic waves, the second signal of the difference frequency at the output of the second mixer between the incident electromagnetic waves and the reflected waves shifted 0 in phase by the angle p / 4 is selected, the cross-correlation function between these signals and the time shift corresponding to it is calculated maximum, determine the level of the liquid in the container (see Patent 2650611, published 04.16.2018).

The disadvantage of this method is the use of 5 high-cost meter, the need to provide the meter with power supply of tens of volts and a power of several watts, which limits the use of the meter in wireless systems. Also known from the prior art is a method for determining the height of the liquid level, which consists in the fact that optical radiation is directed along a sufficiently transparent extended body (tape, rod, fiber) immersed in a liquid, and radiation escaping from the body is recorded, by which the height of the liquid level is judged , radiation in the body is directed at angles of incidence to the lateral surface of the body, providing the greatest radiation output into the liquid from the lateral surface, and a burst of radiation exit from the lateral surface into the liquid near the level is recorded by a coordinate photodetector located along the body (see Patent RU2231028, published on 20.06. 2004).

The disadvantage of this method is the need to use photodetectors, which are a key element that determines the measurement accuracy. An increase in the measurement accuracy is achieved by increasing the number of photodetectors, which affects the cost of the meter and the consumed electricity. It should be borne in mind that this method does not allow assembling a universal level sensor for several types of liquids (since this requires different materials of transparent tape) and limits the use of the meter outside closed tanks.

Known hydrostatic method for measuring the level of a liquid, based on the determination of the hydrostatic pressure exerted by the liquid at the bottom of the tank. Hydrostatic pressure depends on the height of the liquid column above the measuring device, on the density of the liquid and is determined by the formula P = Hpg, therefore, the liquid level is determined by the formula H = P / (pg), where H is the height of the liquid column, m; P is the pressure of the liquid column, Pa; p is the density of the liquid, kg / m3;

g is the acceleration of free fall.

When measuring the level with a differential pressure gauge, an additional equalizing vessel is installed, filled to a certain level with the same liquid as the apparatus. The height of the liquid column in the other elbow of the differential pressure gauge changes with the level in the apparatus. Each level value in it corresponds to a certain pressure drop, determined by the distance in height between the apparatus and the device. If the apparatus operates at atmospheric pressure, the equalizing vessel is placed at the zero level mark, if under pressure - at the maximum level (see, for example, "LEVEL MEASUREMENT AND CONTROL DEVICES", A.Yu. Ageev, L.N. Lokhtina , MINISTRY OF EDUCATION AND SCIENCE OF THE RUSSIAN FEDERATION, Federal State Autonomous Educational Institution of Higher Professional Education, National Research Nuclear University MEPhI

Seversk Technological Institute - branch of NRNU MEPhI (STI NRNU MEPhI), Seversk 2014).

The disadvantage of this method is that the use of this method is possible only in a specially prepared reservoir, tank, container and, or in the case of use in an open reservoir, either the placement of a leveling vessel is required with the provision of measures to protect it from physical influences that can damage the device in such a reservoir ... This is a significant limitation of the application and makes the measurement method expensive. Also for automation of removal it is necessary to use one of the level meters in the level vessel.

The closest to the proposed method is a method for measuring the water level using a data collection center and a hydrological station, on which an automated hydrological complex is installed, which includes a hydrostatic level gauge and a controller. Using a level gauge installed at the place where the water level is measured, the water level is measured at the point of its installation at the hydrological post by measuring the pressure of the height of the water column above the pressure sensor. Using a controller connected by a cable with a level gauge, they control the measurement process, accumulate measured data on the water level, store data and automatically transfer measurement data via communication channels to the data collection center to the server (see Guidance document RD 52.08.869-2017 " Methods for measuring the water level in reservoirs and watercourses by automated hydrological complexes ",

MINISTRY OF NATURAL RESOURCES AND ECOLOGY OF THE RUSSIAN FEDERATION, Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet), St. Petersburg 2017).

The disadvantages of this method when using a hydrostatic level gauge are related, are: the need to ensure the required error and as a consequence of taking into account the water temperature, and, consequently, the rise in cost of the level gauge; the technique involves the installation of the level gauge in a special protective environment, which implies the need for preliminary preparation of the measurement post; protection required cable communication line connecting the level gauge to the controller (cable protection must be carried out both under water and in the ground). A controller must also be used. All this negatively affects the cost and complexity of the application of this method.

A float level gauge is known from the prior art, comprising a sealed tube made of non-magnetic material, a float with an annular permanent magnet, mounted concentrically with the tube and movable along it. Inside the tube there are resistors connected in series in a circuit, both ends of which are connected to a current source through a communication line, and reed switches, one of the outputs of which is connected to the junction point of two resistors, the other outputs of the reed switches are connected to each other, a liquid level indicator. In addition, a series-connected RC filter, a differential amplifier, an analog-to-digital converter are introduced, the output of which is connected to the input of a microprocessor controller of a liquid level indicator with a digital display and a keyboard, and one of the inputs of the RC filter is connected through a communication line with a common point of interconnected outputs reed switches, and the other input of the RC filter is connected to the current source and to the end of the resistor chain that is connected to the reed switch. (see, Patent RU22245, published 10.03.2002).

The disadvantage of this device is the presence of movable elements, which negatively affects the reliability of the sensor, which may also require periodic maintenance and limits the use in conditions in which the liquid can freeze. Also known from the prior art is a device for measuring the level of water in reservoirs, including a vertically located pipe, in the lower part of which there is an opening for supplying water to the cavity of the pipe. Inside the pipe, there is a freely floating float, which is made in the form of a hollow or solid disk that overlaps the pipe section along its inner contour with a gap, as well as a distance meter located in the upper part of the pipe, the probe beam of which is directed mainly to the central part of the disk floating in the water. The pipe in the upper part contains a protective casing against meteorological precipitation and an outlet connecting the pipe cavity with the external air of the reservoir, while the pipe in the lower part contains a nozzle with an opening, which is located coaxially to its main axis (see Patent RU2627569, published 08.08.2017. ).

The disadvantage of this device is the presence of moving elements, which negatively affects the reliability of the sensor, which may also require periodic maintenance and limits the application in conditions in which the liquid can freeze. Also, the method uses a beam distance meter, which is expensive and may require periodic maintenance to clean the optical elements.

The closest to the proposed device is a device for determining the level of a liquid containing a tube with one open end, a sealed partition is installed inside the tube to form two cavities in the tube, while in the first cavity formed on the side of the open end of the tube, a first air pressure sensor is installed, and in the second cavity formed with the sides of the closed end of the tube, a second air pressure sensor is installed, a control controller with software connected to each air pressure sensor, and the tube has a through hole in the area between the sealed partition and the closed end (see US 9958308 B2, published 01.05.2018).

The disadvantage of the closest solution is the lack of the possibility of remote automated monitoring of the liquid level and timely detection of changes in the liquid level.

The technical problem solved by the invention is the elimination of all of the above disadvantages, as well as the possibility of automated control of the liquid level by wireless means at any place.

The technical result of the invention is to improve the accuracy and reliability of monitoring the liquid level, as well as to increase the information content and reliability of information about the change in the liquid level, to ensure the possibility of timely detection of changes in the liquid level, to provide the possibility of remote automated monitoring of the liquid level using contactless pressure sensors, eliminating the need to lay wired communications , ensuring the possibility of long-term operation without the need for maintenance by eliminating moving mechanical parts, as well as acoustic and optical sensors that fail in contact with contaminated wildness.

The technical result is achieved thanks to a device for monitoring the level of liquid, which implements the claimed method monitoring the liquid level containing a tube with one open end, a sealed partition is installed inside the tube to form two cavities in the tube, while the first air pressure sensor is installed in the first cavity formed on the side of the open end of the tube, and in the second cavity formed on the side the closed end of the tube, a second air pressure sensor, a radio transmitting device, a control controller with software connected to the radio transmitting device and to each air pressure sensor are installed, a power supply connected to the control controller and to the radio transmitting device, and the tube has a through hole in the area between sealed baffle and closed end.

In addition, the first air pressure sensor is preferably made waterproof.

The radio transmitting device may include a network module and an antenna.

Also, the technical result is achieved due to the implementation of the method for monitoring the liquid level, which consists in the fact that at the place of monitoring the liquid level, the above device is installed with the open end of the tube downward above or below the liquid level, using the first pressure sensor, the air pressure in the first cavity of the tube is measured, and using the second pressure sensor measures the air pressure outside the tube, compares the pressure difference between the first and second pressure sensors using the control controller, and periodically sends messages using a radio transmitter using LPWAN or NBIoT technology on the at least one base station installed in the radio signal propagation zone of the device, each message from the device containing the identification data of the device and the value of the pressure difference (and, if necessary, the readings of the control pressure sensor), each message is received from the device using at least one base station, it is processed and sent to the network server, each message is received from at least one base station using the network server, the liquid level is determined based on the pressure difference and processed messages are sent to the user's electronic device, each of which contains the identification data of the device and the height of the liquid level , and the device sends messages periodically at constant time intervals when the pressure difference between the first and second pressure sensor is within the specified maximum value, and when the pressure difference changes more than the specified maximum value, immediate transmission of messages is carried out at shorter time intervals, according to which the user judges the change in the liquid level more than a predetermined maximum value.

In addition, when at least one base station receives messages from the device, it can filter the received messages by discarding corrupted and / or false messages.

In addition, when the network server receives messages from at least one base station, it can filter the received messages by discarding corrupted and / or false messages, and aggregating the received messages. messages by combining into one message the same message received by different base stations.

In addition, prior to the start of sending messages to at least one base station, the frequency of sending messages can be configured.

In addition, the user's electronic device can have software, while the network server can be configured for this software by entering the device identification data into the network server database and associating with the software of the user's electronic device, and the network server can store the received from the software. at least one base station of messages, as well as values of the liquid level, and can determine the software of the electronic device of the user with which the device is associated.

In addition, the liquid level can be determined by calculating the value of the liquid level height using the following relationship: where

H is the height of the liquid level relative to the lower open end of the tube, Pa;

DR is the value of the pressure difference between pressure sensors, m;

p is the density value of the liquid, the level of which is measured, kg / m ³ ;

L is the height of the location of the first air pressure sensor relative to the open end of the tube, m.

Р ₀ - pressure value of the second (control) pressure sensor, Pa. In addition, the above device can be used, the tube length of which is not less than the expected change in the liquid level, while before installing the device, the tube length value can be entered into the server database and associated with the device identification data.

The invention is illustrated with the help of drawings, where Fig. 1 shows the proposed device for monitoring the liquid level; in fig. 2 shows an example of installing the device in a tunnel; in fig. 3 shows an example of installing the device in a tank (container); in fig. 4 shows an example of installing the sensor on a support of a bridge or other permanent structure, for example, on a river or other body of water; in fig. 5 schematically shows the connection of the elements with which the proposed method is carried out.

The proposed method for automated wireless monitoring of the liquid level with the device 1 for implementing the method is intended for timely detection of flooding and control of the liquid level, for example, in basements, tunnels, workshops, collector wells, in certain areas of streets, and other places where it is necessary. Also, the proposed method with device 1 is intended for monitoring the water level in case of floods, monitoring the water level of pools, tanks with liquid, reservoirs of water pumps, water treatment facilities, etc., as well as for monitoring the water level of such reservoirs as: lakes, rivers, reservoirs and others reservoirs.

The proposed method is implemented using a set of technical means interconnected by wireless communication channels and including (but not limited to): device 1 for monitoring the liquid level; base station 2 (network gateway); network server 3 processing information (data); an electronic device 4 of an end user with special software (user application), while a phone, smartphone, tablet, laptop, personal computer or other device (software or service) with which the user monitors the level can be used as an electronic device 4 liquids.

The device 1 for monitoring the liquid level is an LPWAN or NBIoT liquid level sensor and contains a housing made in the form of a hollow tube 5, mainly of cylindrical shape (or any other shape), having the required length, which should not be less than the expected change in the liquid level in monitoring site. The tube 5 has one open end 6 and one closed end 7, for example, by means of a removable cover 8, which provides access to the inside of the tube 5 to the components installed in the tube 5. Inside the tube 5, a sealed partition 9 is installed to form two cavities 10 and 11. The partition 9 divides the inner space of the tube 5 into two insulated cavities 10 and 11. In the cavity 10 formed on the side of the open end 6 of the tube 5, the first moisture-proof air pressure sensor 12 is placed and rigidly installed, the sensor 12 being installed mainly closer to the partition 9 and further from the open end 6 of the tube 5. The lower end of the tube 5 can be protected from freezing (icing) by organizing the expansion in such a way that the lower part of the tube 5 will have a larger diameter than the diameter of the rest, and also, but not only, by the use of materials or body coatings minimizing accumulation of liquid droplets on the surface or in another suitable way.

In the cavity 11 formed on the side of the closed end 7 of the tube 5, the second control air pressure sensor 13 (the readings of the sensor 13 are necessary to take into account the change in atmospheric pressure), the power element 14, the control controller 15 with built-in software and the radio transmitting device 16 are placed and rigidly installed The radio transmitting device 16 includes a network module (where the controller 15 can be combined with the network module) and an antenna. The control controller 15 is connected to both air pressure sensors 12 and 13 by means of wires or by being executed on one single board. In this case, the wires or part of the board connecting the first pressure sensor 12 with the controller 15 are routed through the sealed partition 9. The controller 15 controls the air pressure sensors 12 and 13, analyzes and processes the data received from the sensors 12 and 13, sends messages to the network module , storage of settings for the frequency of sending messages (signals). The network module provides transmission of messages (signals) in the data transmission network, as well as storage of the necessary parameters for operation in the corresponding data transmission network. Moreover, in the case of message transmission using LPWAN technology, the network module is a radio module that transmits data over the LPWAN channel; and in the case of message transmission using NBIoT technology, the network module is an NBIoT module, i.e. a cellular modem and the cellular data network protocol is used for data transmission. Power element 14 is designed to ensure autonomy of operation device 1 and is connected to the radio transmitting device 16 and to the controller 15. The antenna is designed to ensure the transmission of messages (signals) to the radio channel (cellular network).

The tube 5 has a through hole 17 in its wall. The hole 17 is formed in the area between the partition 9 and the closed end 7, i.e. in the formation zone of the second cavity 11. The hole 17 is intended for communication of the cavity 11 with the external environment and can be protected from the ingress of precipitation, dust and dirt in any suitable way.

Device 1 is connected via wireless communication channels with base station 2 (or with several base stations 2) and provides transmission to base station 2 of messages containing data on the pressure values of sensors 12 and 13 (the pressure difference between sensors 12 and 13).

A method for automated wireless monitoring of a liquid level using a device 1, a base station 2, a network server 3 and a user's electronic device 4 with special software is as follows.

For the implementation of the proposed method, it is important to place the device (s) 1 and ensure the configuration of the network server 3 in such a way that the delivery of messages from the device 1 to the application of the user's electronic device 4 is provided. For this, the network server 3 is configured for the application of the user's device 4. At this stage, the unique identifiers (identification data) of device 1 (or several devices, depending on their number used at the monitoring site) are entered into the server 3 database and associated with the application of the electronic device 4 user. The unique identifier of device 1 is, for example, the network address or identification number of device 1 (ID) or ICCID, or otherwise (determined by the used LPWAN or NBIoT technology). When implementing the method, the length of the tube 5 is important, which must be at least the expected change in the liquid level at a specific location for monitoring the liquid level. The data on the length of the tube 5 of the device 1 is entered into the database of the server 3 at the stage of manufacturing the device 1, and the length of the tube 5 is associated with the unique identifier of the device 1.

LPWAN or NBIoT liquid level sensor 1 is installed in the place where it is necessary to control the liquid (water) level. The device 1 is installed vertically with the open end 6 of the tube 5 downward above the liquid level or below the liquid level, depending on whether a decrease in the height of the liquid level or an increase in the level at the control point is expected. Depending on the place where it is necessary to monitor the liquid level (room, reservoir, street, etc.), the tube 5 is installed with the open end 6 down so that the end 6 is located above the liquid level (above the reservoir level) or above the floor , or above the ground, or above the ceiling, or above the bottom of the tank at a distance of about 1 cm.The distance between the level and the open end 6 of the tube 5 may be different, depending on the expected change in the liquid level, for example, 0.5 cm. or 1 , 5 cm or more, but not more than the value of the height of the initial critical liquid level at a specific monitoring site. The distance between the level and the open end 6 of the tube 5 is determined by the particular tasks of monitoring the liquid level, while there are no restrictions on the height from the floor / bottom. Also, when implementing the method, it is possible that the device 1 is installed vertically with the open end 6 of the tube 5 down below the liquid level. This installation is necessary when monitoring liquid level decrease, for example, in tanks, reservoirs, wells, etc. In this case, the tube 5 is immersed in the liquid with the open end 6 to the required distance, while the open end 6 is located in the liquid at the level that corresponds to the minimum critical level at the corresponding monitoring location.

Thus, in FIG. 2 shows a variant of placing the device 1 in a tunnel, where 18 is the walls of the tunnel, 20 is a liquid; in fig. 3 shows a variant of placing the device 1 in a tank, where 19 are the walls of the tank; in fig. 4 shows a variant of placing the device 1 on water bodies, where 21 are the supports of a bridge or other capital structure. These options for placing the device 1 are not limited, and the device 1 can be fixed in any possible way with the open end 6 above the liquid level (or below the liquid level) on pre-prepared supports (pillars, ceilings, walls, etc.).

Before installing device 1 in the place where it is necessary to control (monitor) the liquid level, carry out the following: a) prepare device 1 for operation in accordance with the manufacturer's recommendations, including setting the frequency of sending messages; b) determining the optimal location for placing the device 1 in accordance with the manufacturer's recommendations; c) installation of the device 1 on controlled objects, and for the installation of the sensor 1, preparation of fasteners and / or preparation of the object itself may be required. There are no significant restrictions on the place of installation (fastening) of the device 1. The methods of fastening the device 1 are not limited and can be any.

After the device 1 is installed at the control point and adjusted, the liquid level is monitored directly.

A device 1 located at a certain distance above the liquid level 20 (including below the liquid level 20 when the open end 6 of the tube 5 is immersed in the liquid 20) continuously monitors the air pressure in the lower part of the tube 5 and the air pressure outside the tube 5. The change in air pressure inside the tube 5 occurs when the liquid level 20 rises (or falls) above the lower edge of the tube 5 (or when the liquid level in the cavity 10 of the tube 5 drops towards the lower edge, including to the very bottom edge). In the monitoring process, the air pressure in the first cavity 10 of the tube 5 is measured using the first pressure sensor 12, and the air pressure outside the tube 5 is also measured using the control pressure sensor 13 (in the cavity 11 through the hole 17). After measuring the air pressure by sensors 12 and 13, the pressure difference measured by the sensors 12 and 13 is compared using the controller 15, this difference is analyzed, and, based on the results of the analysis, the pressure difference values in messages (radio signals) are periodically sent to the radio channel by means of the radio transmitting device 16. Periodic sending of messages is carried out using a radio transmitting device 16 using LPWAN technology or using NBIoT technology (depending on the availability of a coverage area at the installation site of device 1, the range of signal transmission from the radio transmitting device 16, etc.). Messages are sent to base station 2 (or to several base stations 2) installed in the radio signal propagation zone of radio transmitting device 16. Moreover, before the messages are sent to base station 2, on device 1 (on controller 15), the message sending frequency is adjusted. The setting of the sending frequency is carried out mainly for messages about the invariability of the liquid level 20.

Each message from device 1 contains the identification data of the wireless device 1 and the pressure values of both sensors 12, 13 (or the value of the pressure difference between sensors 12 and 13, or the liquid level value calculated on the sensor 20). With a slight change in the liquid level 20, i.e. within the specified maximum value, which is up to 10%, messages of the first type ("periodic pressure readings") are transmitted to the radio channel.

The magnitude of the change in the level of the liquid 20 can be estimated, for example, but not only, according to the following conditions:

- The change per unit of time in the difference in readings between the values of the main sensor 12 (barometer) and control sensor 13 (barometer) does not exceed the specified value.

- Change per unit of time of the difference between the current pressure difference and the previous difference for the previous period of time.

Thus, messages of the first type are sent at a constant liquid level 20 or with a slight (non-critical) change in the liquid level 20. Messages of the first type are sent periodically at constant time intervals, which are set by the user. At the same time, the user, depending on the monitoring task, on the operating conditions, on his needs and on the installation site of the device 1, where monitoring is carried out, can set up any time intervals for sending messages (after a few seconds or a few minutes, or every hour, or once a day at a certain time, or once a month at a certain time of the corresponding day, and so on).

In case of detection of a sharp change in the pressure difference in comparison with the previous readings by more than the value of the set maximum value (over 10%), or with a constantly changing value of the pressure difference in short periods of time, an immediate (instant) out-of-order transmission of the second type of messages ( "anxiety"). Messages of the second type are sent outside the user-defined schedule for the first type of messages and at smaller time intervals (for example, in a second or in a minute or in an hour, but not more than the time interval set for messages of the first type). Thus, the "alarm" message is transmitted when there is a sharp change in the height of the liquid level 20, or with a constantly changing height of the liquid level 20 in short periods of time (when the preset limit values of the pressure difference are exceeded). According to messages of the second type, the user judges the change in the height of the liquid level 20 more than a predetermined maximum value (or less than a predetermined minimum value in the case when the tube 5 is immersed in the liquid 5 during installation and the decrease in the liquid level 20 is monitored).

Thus, device 1 transmits two types of messages: a) "periodic pressure readings"; b) "anxiety". The message of the "periodic pressure readings" type is intended to transmit to the user application information about the operability of the device 1 itself and the radio channel to the base station 2, as well as to reflect the current values of the pressure of sensors 12, 13 and, accordingly, the current height of the liquid level 20. Message of the " alarm "is sent when a change in the pressure difference and, accordingly, the height of the liquid level 20 is more (or less) than the normal height of the liquid level 20 is detected, and to minimize the probability of non-delivery of messages of the" alarm "type, they are sent multiple times (for example, 2-5 times, or more number of times depending on the user's need).

To send the device 1 messages (radio signals), LPWAN technology or NBIoT technology is used, and the data transfer protocol (cellular network) is determined by the LPWAN technology or NBIoT technology used in a particular case. The frequency range depends on the LPWAN technology or NBIoT technology used in a particular case and the rules and permits in force in a particular region.

To receive messages from the device (s) 1, at least one base station 2 (network gateway) must be present in the radio signal distribution area of the radio transmitting device 16. However, there may be a larger number of base stations 2, and to receive a message from device 1, already pre-installed base stations 2 can be used, or, if they are absent, base station 2 (or several base stations 2) is installed in the signal propagation zone from sensor 1.

After the device 1 sends messages, using base station 2 (or several base stations 2) are received from devices 1 each message, process it and send it to the network server 3.

Base station 2 (base stations) carries out unconditional automated transmission of messages received from the radio channel to the message processing server 3 (taking into account the need to filter messages). Base station 2 sends a message to server 3 immediately after receiving it from the radio from device 1. The method of transmitting data by base station 2 to server 3 is determined by a specific model of base station 2. In particular, the following methods are widespread - via a fiber-optic channel, ethernet channel, via a cellular network and via WiFi. The data transmission channel used is determined by the composition of the protocols and data transmission supported by the network gateway.

Server 3 can be located both in the "cloud" and on the user side, this is determined by the LPWAN technology or NBIoT technology used in a particular case.

After the server 3 receives each message from the base station 2, the network server 3 processes each message received from the base station 2 (stations) and transfers these messages to the end-user application to its electronic device 4. When processing messages on the pressure and taking into account the length of the tube 5, the height of the liquid level 20 at the place of installation of the device 1 is determined. The liquid level 20 is determined by the pressure difference by calculating the value of the height of the liquid level 20. The calculation of the height of the liquid level 20 is carried out using the following formula:

DR is the value of the pressure difference between pressure sensors, m;

Р ₀ - pressure value of the second (control) pressure sensor, Pa.

In addition to the fact that the network server 3 processes the messages received from the base station 2, calculates the values of the height of the liquid level 20 and sends messages to the end-user application, the server 3 also stores the messages received from the base station 2, stores the pressure indicators of the sensors 12 and 13, storing the calculated values of the height of the liquid level 20 and determining the application of the electronic device 4 of the user with which the devices 1 are associated.

All messages received from device 1 must be filtered and aggregated. This is necessary to identify messages that were distorted during transmission over the radio channel and remove them from further processing. Filtering can be carried out both at base station 2 (network gateway) when receiving messages from device 1, and on network server 3 when receiving messages from base station 2. Aggregation is performed on network server 3 when receiving messages from base station 2 (base stations) ... When filtering messages, corrupted messages and / or false messages are discarded; discard both corrupted and false messages, or discard only corrupted messages if there are no false messages, or discard only false messages if there are no corrupted messages. Aggregation messages are carried out to combine into one message the same message received at different base stations 2.

After the network server 3 has received each message from the base station 2, processed it, calculated the liquid level 20, using the network server 3, the already processed messages are sent via the data transmission channel to the user's electronic device 4 (user application), with each processed the message includes the identification data of the device 1 (for example, its unique identifier) and the value of the calculated liquid level 20. The method of data transmission is determined by the composition of the protocols supported by the network server 3 and the user application. An example of data transfer can be a public or proprietary API, or the open MQTT (Message Queuing Telemetry Transport) protocol, or another suitable protocol for data transfer.

Upon receipt by the electronic device 4 from the server 3 of each processed message on the device 4, using the application, the identification data of the device 1 (correlation of the sensor ID 1) is compared with the physical object of control, in the place of which the device 1 is installed, and the user is notified (informed). Informing the user is carried out by periodically sending him messages (after certain periods of time, configured by the user), including the identification data of the device 1 and the current value of the pressure indicators of sensors 12 and 13 (the first type of message is "periodic pressure readings"). Upon receipt of this type of message, the user using his device 4 can check the status at any time the operability of the device 1 and the radio channel, and also make sure that the liquid level 20 does not change, or that it changes slightly. In this case, the electronic device 4, upon periodic receipt of the message "periodic pressure readings", can automatically notify (inform) the user of its operability by reproducing a signal in any possible way (playing a sound signal, light indication, vibration, etc.), or it can be in passive state (state of rest) and the user independently using the application can check the operability of device 1 and the radio channel, as well as the current liquid level 20 (in this case, when the user opens the application on his device 4, the application can inform the user in any specified way). And with a sharp change in the liquid level 20 or a constant change in a short period of time, i.e. when the pressure difference changes more than a predetermined maximum value, the user is notified by sending him a message including the identification of device 1 and an alarm (the second type of message is "alarm"). Thus, when the level of the liquid 20 changes at the place of installation of the device 1, the user is notified of this using his device 4 by playing an alarm signal.

The method of informing (notifying) the user can be any, for example, by giving an alarm signal on the device 4 or by light indication, or vibration of the device, or in any other possible way, including a combination of these methods. Moreover, the user's application can display, for example, a map of the location of monitoring objects with devices 1 or a list of such objects, and the user has the opportunity in real time, being at any distance from the monitoring object, to check the liquid level 20.

Thus, thanks to the implementation of the proposed method, continuous monitoring of the liquid level is provided in any places where it is necessary to carry out, for example, in order to detect flooding or in order to detect a critical change in the height of the liquid level 20.

If we briefly describe the proposed method, it is carried out as follows. The device 1 periodically sends messages of the type "periodic pressure readings" to the base station 2, which sends these messages to the server 3, and then the server 3 calculates the liquid level and sends the processed messages to the user's electronic device 4. The message "periodic pressure readings" is sent at the necessary frequency for the user at constant time intervals and the user can at any time using the application of his device 4 check the operability of the device 1 and the radio channel, as well as the current liquid level. As soon as the liquid level changes to a more critical value, device 1 immediately sends an "alarm" message also to base station 2, which sends this message to server 3, and then server 3 calculates the liquid level and sends a processed message with the calculated liquid level value to the device 4 users. When the application of the user's device 4 receives this type of message ("alarm"), the device 4 notifies the user of the fact of a change in the liquid level by sending an alarm signal on the device 4 or by a light indication or in any other possible way. Upon receiving an “alarm” message, the user can immediately respond to changes in the liquid level and take the necessary measures to eliminate the adverse consequences.

Thanks to the use of base stations 2, messages from device 1 can be transmitted to any distance, and the user can be anywhere and at any distance from device 1. In accordance with the generally accepted ideology of building LPWAN networks or NBIoT networks, placing base stations 2 (network gateways) and it is the operator's job to provide radio coverage.

In addition, thanks to the proposed method, it is provided:

- remote automated control of the liquid level 20 based on device 1 with inexpensive air pressure sensors 12, 13, providing an accuracy comparable to significantly more expensive level sensors;

- remote automated control without the need to lay wired communications;

- no need for maintenance of device 1 and long-term operation from one battery 14 (3-5 years);

- the versatility of the device 1 and the applicable method - the possibility of using the method to control the liquid level in reservoirs, reservoirs and a wide range of premises and technological facilities;

- no significant restrictions on the type of controlled liquid;

- no restrictions on the range of the minimum and maximum measured liquid level 20; - low cost of device 1 and the total cost of ownership of the system due to the long life of device 1 and the absence of the need to maintain device 1;

- cost reduction for system implementation and short implementation period, as well as cost reduction for further operation.

Due to the use of air pressure sensors 12 and 13 for measuring the liquid level, the need for the use of moving mechanical parts, as well as acoustic and optical sensors, the use of which is not advisable due to potential contact with the liquid, and can be difficult due to failure on contact with contaminated liquid, or due to the characteristics of the control room.

The architectural solution is based on the generally accepted 1oT architecture, which provides for a network gateway, a server that processes messages and sends them to the user's application.

Claims

Claim

1. A method of monitoring the liquid level, which consists in the fact that a device for monitoring the liquid level is installed at the place of monitoring the liquid level, including a tube with the first and second air pressure sensors installed in it, a radio transmission device and a control controller, and the installation of a device for monitoring the liquid level carried out with the open end of the tube downward above or below the liquid level, using the first pressure sensor measure the air pressure in the first cavity of the tube, and using the second pressure sensor measure the air pressure outside the tube, compare the pressure difference between the first and second pressure sensors using the control controller , and periodically send messages using a radio transmitting device using LPWAN or NBIoT technology to at least one base station installed in the radio signal propagation zone of the radio transmitting device, each message from the device for monitoring ur The liquid level contains the identification data of the liquid level monitoring device and the pressure difference value, with the help of at least one base station, each message is received from the liquid level monitoring device, processed and sent to the network server, with the help of the network server, each message is received from at least one base station, each message, the liquid level is determined by the pressure difference and processed messages are sent to the user's electronic device, each of which contains the identification data of the device for monitoring the liquid level and the value of the liquid level, and sending messages by the device for monitoring the liquid level are carried out periodically at constant time intervals when the pressure difference between the first and the second pressure sensor is within the specified maximum value, and when the pressure difference exceeds the specified maximum value, messages are immediately transmitted at shorter time intervals, according to which the user judges about a change in the liquid level more than the specified maximum value.

2. The method according to claim 1, wherein when at least one base station receives messages from the liquid level monitoring device, it filters the received messages by discarding corrupted and / or false messages.

3. The method according to claim 1, wherein when the network server receives messages from at least one base station, it filters the received messages by discarding corrupted and / or false messages, and aggregates the received messages by combining one and the same message received by different base stations.

4. The method of claim 1, wherein prior to the start of sending messages to at least one base station, the periodicity of sending messages is adjusted.

5. The method according to claim 1, wherein the user electronic device has software, wherein the network server is configured for the software by entering the identification data of the liquid level monitoring device into the network server database and associating with the software of the user electronic device, and the network server stores the received from at least one base the station of messages, as well as the values of the liquid level, and determines the software of the electronic device of the user, with which the device for monitoring the liquid level is associated.

6. The method according to claim 1, wherein the liquid level is determined by calculating the liquid level height value using the following relationship: where

DR is the value of the pressure difference between pressure sensors, m;

Po is the pressure value of the second pressure sensor, Pa.

7. The method according to claim 1, in which a device for monitoring the liquid level is used, the tube length of which is not less than the expected change in the liquid level, and before installing the device for monitoring the liquid level, the value of the tube length is entered into the server database and associated with identification data devices for monitoring liquid level.

8. A device for monitoring the liquid level, implementing the method according to claims 1-7, containing a tube with one open end, a sealed partition is installed inside the tube to form two cavities in the tube, while in the first cavity formed on the side of the open end of the tube , the first air pressure sensor is installed, and in the second cavity formed on the side of the closed end of the tube, installed a second air pressure sensor, a radio transmitting device, a control controller with software connected to the radio transmitting device and to each air pressure sensor, a power supply connected to the control controller and to the radio transmitting device, and the tube has a through hole in the area between the sealed partition and the closed the end.

9. The device of claim 8, wherein the first air pressure sensor is waterproof.

10. The apparatus of claim 8, wherein the radio transmitting apparatus includes a network module and an antenna.