RU2653566C1 - System of the water level in piezometric wells automated measurement - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: invention relates to hydraulic power industry, in particular to the long objects such as hydraulic structures (HTS) technical condition monitoring automated facilities, ground dams, dams with a large number of spaced measuring points, and can be used, in particular, in remote monitoring systems of water filtration, water level in pressure and non-pressure piezometric wells and water level in the hydraulic power plants hydro level instruments. System consists of the Bragg fiber gratings based fiber-optic pressure sensors placed in piezometric wells, from the sensors groups measuring channels are created, in each channel, by fiber optic cables the sensors are connected to each other and to the included in each channel passive fiber depolarizer, wherein each channel is connected to a multiplexer-switch through the passive fiber depolarizer, which in according to the certain program connects the channels one by one to the polling device, recording the resonant wavelength change, calculating the water column pressure per sensor and this water column height in each piezometric well, transmitting the calculated values to the HPP control panel for the water column height calculated values visualization and automatically comparing with the permissible ones and sending the alarm signal to the HPP control panel when the permissible values are exceeded.

EFFECT: minimization of the measuring devices maintenance and ensuring their vandal-resistance and energy independence, automating of the readings comparing process with acceptable values.

1 cl, 3 dwg

Description

The invention relates to hydropower, in particular to automated means for monitoring the technical condition of extended facilities, such as hydraulic structures (hydraulic structures) - soil dams, dams with a large number of spaced measuring points, and can be used, in particular, in remote control systems for water filtration, water level in pressure and non-pressure piezometric wells and water level in hydraulic levels of hydroelectric power stations. Monitoring automation is required to ensure the safety of the surrounding areas in case of dam integrity and to prevent emergency situations.

The problem of monitoring filtration flows in soil dams has arisen with the creation of such dams and accidents with them. The main way to reduce filtration flows in a soil dam is to use an anti-filtration core or screen during the construction of the dam and organize the drainage of the filtration flow from the body of the soil dam to the downstream.

Both of these methods are very effective, however, each of these elements of the soil dam has its own limited service life: the core and the screen are destroyed under the pressure of water, and the drainage is silted and reduces its throughput over time.

Therefore, despite the presence of these structural elements, monitoring of the level of the depression curve in the dam body and its comparison with the level of the depression curve for the corresponding safe filtration flow rate is required.

To measure the depression curve in the body of the dam, piezometric wells are arranged during construction. Monitoring the water level in piezometric wells allows you to evaluate the filtration flow in the dam. Comparison of the filtration flow with a safe level and signaling of an excess in the shortest possible time allows to increase the safety of operation of hydraulic structures.

The following methods are known for measuring the water level in a piezometric well:

• A device for determining the dynamic level of water in a piezometric well with an electric level meter when lowering the tip of the level gauge on an insulated wire. In this case, the tip of the level gauge is lowered in metal piezometric tubes specially installed for this purpose (Hydrogeologist Reference Guide, Volume 2, edited by V.M. Maksimov, L .: Nedra, 1967).

• A capacitive level gauge that allows you to measure the liquid level in one piezometer.

DEVICE FOR MEASURING THE LEVEL OF ELECTRICALLY CONDUCTING LIQUID (G. Ya. Shaidurov, AS No. 2332643 from M Cl. G01F 23/26 from 01/18/2007. Bull. INV. No. 24, 2008).

• Acoustic Water Level Measurement, US Pat. No. 7,178,396.

• Measurement of the height of a water column by the hydrostatic method. US Pat. No. 4,142,411.

Known automated systems for collecting data from several measuring points and transferring them to a control computer:

• The system of monitoring the water level in the well by the acoustic method, with the accumulation of information in the sensor and the transfer of accumulated data to the computer in one communication session. U.S. Patent Application US 20140009302 A1.

• A wireless interrogation system for several sensors located at a distance of up to 150 m. The system consists of a polling device connected via a wireless communication channel to several sensors located no more than 150 m from the device and several sensors located in the wells. Each sensor consists of an antenna, an RF transceiver, a processor, an electrochemical cell, and a sensor module. Patent Application US 20090066536 A1.

By the greatest number of similar features and achieved by using the result, this technical solution is selected as a prototype of the claimed invention.

The prototype system has the following disadvantages:

a) The volatility of the measuring equipment, and the consequent need for providing power to each measuring point or servicing the autonomous power supply of each sensor.

b) The ability to measure with a single device the water level in only one piezometric well.

c) Lack of transmission of water level data in piezometers immediately after measurement.

d) Placing expensive equipment in the well head, in the public domain.

Object of the invention

Creation of a more efficient and non-volatile system for measuring the level of water column in piezometric wells of a hydroelectric dam of a hydroelectric power station, in which the process of obtaining measured values and transmitting data to a hydroelectric station control panel is automated, as well as the process of comparing the readings with acceptable values, the measurement devices are minimized and maintained vandal resistance.

The task is achieved in that the system consists of a device for interrogating fiber-optic pressure sensors (interrogator), a multiplexer-switch for measuring channels, passive fiber depolarizers in each measuring channel, fiber-optic cables and fiber-optic pressure sensors based on Bragg gratings.

A distinctive feature of this system is the use of passive fiber depolarizers in each measuring channel and the multiplexing of sensors located in different piezometric wells into one measuring channel.

Fiber-optic pressure sensors based on fiber Bragg gratings located at a fixed depth in piezometric wells are used as data sources for the system. The sensors are mounted on the head of the well with a metal cable.

Description of the system is illustrated in Fig. 1, 2 and 3.

Figure 1 illustrates the position of the sensor in a piezometric well.

On the image:

1 - fiber optic pressure sensor based on a fiber Bragg grating,

2 - mounting cable,

3 - the body of the dam,

4 - fiber optic cable

5 - place of attachment of the cable,

6 - piezometric well,

7 - water column.

The main advantages of fiber-optic pressure sensors over traditional strain-gauge, conductometric and capacitive ones are their non-volatility, the possibility of multiplexing, insensitivity to electromagnetic interference and changes in the electrical conductivity of the measured medium, the absence of the need for periodic verification, and a long service life.

Figure 2 shows the structure of one measuring channel, where:

1 - fiber optic pressure sensors,

4 - fiber optic cable

6 - piezometric wells,

8 - hydroelectric power station building.

When the water level changes, the pressure of the water column on the sensor changes, and as a result, the resonant wavelength of the fiber Bragg grating integrated in the sensor changes.

Figure 3 shows the connection diagram of the measuring channels, where:

1 - fiber optic pressure sensors,

4 - fiber optic cables,

8 - hydroelectric building,

9 - passive fiber depolarizers,

10 - multiplexer

11 is a polling device.

In the measuring channels, pressure sensors are connected in series with each other and with a passive fiber depolarizer, which is inserted into each measuring channel, with fiber optic cables. Through a passive fiber depolarizer, the channel is connected to the multiplexer, which according to a certain program connects the channels in turn to the polling device.

The introduction of a passive fiber depolarizer into the measuring channel ensures the stability of the system to external influences on the fiber optic cable, due to the elimination of polarization effects.

The introduction of the multiplexer allows the use of a polling device with one optical input.

System operation

When the water level changes, the pressure of the water column on the sensor changes, and as a result, the resonant wavelength of the fiber Bragg grating integrated in the sensor changes. The multiplexer connects the measuring channel to the polling device.

Further, the polling device software registers a change in the resonant wavelength, from which, using the calibration data of the sensor, it calculates the pressure of the water column for each sensor of the measuring channel and the height of the water column in each piezometric well, transfers the calculated values to the control panel for visualization, and then automatically compares the calculated values of the height of the water column with the permissible values and generates an alarm signal to the control panel of the hydroelectric station when the permissible values are exceeded.

Using a polling device with one measuring channel, to which a certain measuring channel is connected using a multiplexer in turn, using a software command, can reduce the cost of the entire system.

The use in the system of all measuring devices and lines outside the multiplexer, made passive - working without connecting electricity, ensures its non-volatility and vandal resistance. In addition, these devices and communication lines do not require maintenance and replacement, which reduces the current costs of servicing the GTS.

To ensure sufficient stability of the measuring system to external influences and ensure the required accuracy of 0.5% of the maximum measurement range, a passive fiber depolarizer is included in each channel. It eliminates the effect of influences on the supply fiber and allows to provide the required level of measurement accuracy when using standard telecommunication fiber.

Thus, the proposed system for measuring the water level in piezometric wells of extended objects is economically and technically effective, minimizes the maintenance of measuring devices and ensures their vandal resistance and non-volatility, and automates the process of comparing the readings with acceptable values.

Claims (1)

A system for automated measurement of water level in piezometric wells, including pressure sensors located in piezometric wells, and a polling device, characterized in that fiber-optic pressure sensors based on fiber Bragg gratings are placed in the wells, measuring channels are created from groups of sensors, in each channel the sensors are connected by fiber optic cables to each other and to a passive fiber depolarizer included in each channel, and through a passive fiber depolarizer each channel is connected to a multiplexer-switch that connects the channels in turn according to a certain program with a polling device that records the change in the resonant wavelength, calculates the pressure of the water column for each sensor and the height of this column of water in each piezometric well, transmitting the calculated values to the control panel for visualization and automatically comparing the calculated values of the height of the water column with the permissible values and issuing an alarm to the control panel of the hydroelectric station when exceeding is permissible x values.

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