阅读说明：本技术 核电站冷源取水口拦截网状态监测系统和监测方法 (Nuclear power station cold source water intake interception net state monitoring system and monitoring method ) 是由 何光初 吴侨军 陶长兴 关济实 乐可佳 常新彩 付建鹏 曾清宇 刘超 张波 于 2021-08-23 设计创作，主要内容包括：本申请提出了一种核电站冷源取水口拦截网状态监测系统和监测方法。其中,核电站冷源取水口拦截网状态监测系统包括湿端和干端。湿端布置在水下,包括声波发射模块、声波接收模块、信号处理模块和通信模块。声波发射模块发射声波信号；声波接收模块接收回波信号；信号处理模块处理回波信号,生成对应的立体图像信息并计算出流经目标物的水流流速；通信模块将立体图像信息和水流流速发送至干端。干端布置在水上,包括数据处理模块和显示模块。数据处理模块接收立体图像信息和水流流速,计算出目标物的堵塞率；显示模块用于显示目标物的堵塞状态。本申请提出的核电站冷源取水口拦截网状态监测系统,能够实现对拦截网堵塞状态的监测、分析和诊断。(The application provides a monitoring system and a monitoring method for the state of an interception net at a cold source water intake of a nuclear power station. The system for monitoring the state of the intercepting net at the cold source water intake of the nuclear power station comprises a wet end and a dry end. The wet end is arranged underwater and comprises a sound wave transmitting module, a sound wave receiving module, a signal processing module and a communication module. The sound wave transmitting module transmits a sound wave signal; the sound wave receiving module receives an echo signal; the signal processing module processes the echo signal, generates corresponding three-dimensional image information and calculates the flow velocity of water flowing through the target object; the communication module sends the stereo image information and the water flow velocity to the dry end. The dry end is arranged on water and comprises a data processing module and a display module. The data processing module receives the three-dimensional image information and the water flow velocity and calculates the blockage rate of the target object; the display module is used for displaying the blockage state of the target object. The monitoring system for the state of the intercepting net at the cold source water intake of the nuclear power station can realize monitoring, analysis and diagnosis of the blocking state of the intercepting net.)

1. A nuclear power station cold source water intake interception net state monitoring system is characterized by comprising a wet end (100) and a dry end (200),

wherein the wet end (100) is arranged underwater and comprises a sound wave transmitting module (110), a sound wave receiving module (120), a signal processing module (130) and a communication module (140);

the sound wave transmitting module (110) is used for transmitting a first sound wave signal;

the sound wave receiving module (120) is used for receiving a first echo signal, and the first echo signal is a sound wave signal returned after the first sound wave signal contacts a target object;

the signal processing module (130) is used for processing the first echo signal and generating corresponding stereo image information;

the sound wave transmitting module (110) is also used for transmitting a second sound wave signal;

the sound wave receiving module (120) is further configured to receive a second echo signal, where the second echo signal is a sound wave signal returned after the second sound wave signal contacts the target object;

the signal processing module (130) is further configured to calculate a water flow velocity through the target object according to the second echo signal;

the communication module (140) is used for sending the stereo image information and the water flow velocity to the dry end (200);

the dry end (200) is arranged on water and comprises a data processing module (210) and a display module (220);

the data processing module (210) is used for receiving the stereo image information and the water flow speed, and calculating the blockage rate of the target object according to the stereo image information and the water flow speed;

the display module (220) is used for displaying the blockage state of the target object.

2. The system of claim 1, wherein the acoustic transmission module (110) comprises a transmitter (111) and a transmission array (112),

the transmitter (111) is configured to generate the first acoustic signal or the second acoustic signal;

the transmitting array (112) is used for converting and transmitting the first sound wave signal or the second sound wave signal.

3. The system of claim 2, wherein the transmit array (112) is a single channel spherical shell array.

4. The system of claim 1, wherein the acoustic receive module (120) includes a receiver (121) and a receive array (122),

the receiving array (122) is a planar array and is used for receiving the first echo signal or the second echo signal and converting the first echo signal into a first electric signal or converting the second echo signal into a second electric signal;

the receiver (121) is configured to condition and convert the first electrical signal into a first digital signal or condition and convert the second electrical signal into a second digital signal.

5. The system of claim 4, wherein the receive array (122) comprises a plurality of array elements, the plurality of array elements being arranged in an array.

6. A method for monitoring the state of an interception net at a water intake of a cold source of a nuclear power plant, which is applied to the system as claimed in any one of claims 1 to 5, and is characterized by comprising the following steps:

acquiring a first echo signal, and generating three-dimensional image information corresponding to a target object according to the first echo signal;

acquiring a second echo signal, and calculating the flow velocity of water flow according to the second echo signal;

and determining the blocking state of the target object according to the stereo image information and the water flow velocity.

7. The method of claim 6, wherein acquiring a first echo signal and generating stereo image information corresponding to a target object according to the first echo signal comprises:

transmitting a first sound wave signal through a sound wave transmitting module;

receiving the first echo signal, wherein the first echo signal is a sound wave signal returned after the first sound wave signal contacts the target object;

and converting the first echo signal into the stereo image information.

8. The method of claim 7, wherein converting the first echo signal into the stereoscopic image information comprises:

converting the first echo signal into original point cloud image information;

extracting point cloud information in a predictive range from the original point cloud image information by using a denoising and segmentation algorithm;

separating and reconstructing the point cloud information to generate a plurality of target point cloud information;

and splicing the target point cloud information into the stereo image information by utilizing a registration splicing algorithm.

9. The method of claim 6, wherein determining the blockage status of the target object from the stereo image information and the water flow rate comprises:

mapping the stereo image information and the water flow velocity to the same coordinate system;

acquiring a brightness value of the stereo image information, and normalizing the brightness value;

normalizing the water flow rate;

calculating the blockage rate of the target object according to the normalized brightness value and the normalized water flow velocity;

determining an occlusion status of the target object based on the occlusion rate.

10. The method of claim 6, further comprising:

and when the first echo signal does not meet the preset condition, performing phase compensation on the first echo signal.

11. The method of claim 8, wherein converting the first echo signal into raw point cloud image information comprises:

carrying out array element domain data rearrangement on the first echo signal;

calculating the rearranged first echo signal by using a planar array beam forming algorithm;

converting the first echo signal into a power signal by square detection;

and carrying out post-processing on the power signal.

12. The method of claim 11, wherein post-processing the power signal comprises:

carrying out non-coherent integration on the power signal to obtain distance information of each wave beam;

and selecting the maximum value of the distance information output of each beam, and restoring the maximum value into the original coordinate.

Technical Field

The application relates to the field of cold source systems of nuclear power plants, in particular to a monitoring system and a monitoring method for states of an interception net at a cold source water intake of a nuclear power plant.

Background

The domestic nuclear power plants are mainly distributed in coastal areas, and in recent years, the cold source water intake blockage events of the nuclear power plants frequently occur, so that the serious consequences such as load reduction, shutdown and the like are caused for many times. The types of the related blockage substances mainly concentrate on marine organisms such as seaweed, aquatic weeds, shellfish, acete chinensis, jellyfish, cap screws, fishes and the like, silt such as silt, fragments and sediments and plastics or other foreign matters. Through engineering practice, the interception net can achieve a good interception effect. The intercepting net needs to be cleaned and fished, if the intercepting net is not cleaned timely, secondary serious cold source accidents are easily caused, and even the unit is shut down. The arrangement, the net body material, the stress analysis and the like of the existing interception net lack a unified standard, evaluation and monitoring means; the cleaning and fishing work of the interception net adopts a timing manual fishing mode, the interval time is long, the working efficiency is low, the device cannot be completely adapted to the extremely fast changing marine environment and marine organisms, the extreme marine environment and weather conditions caused by marine organism outbreak are met, and people, ships and equipment cannot perform early warning in advance when the device cannot work normally.

At present, a tension meter and a net position meter are additionally arranged on an interception net or a fish finder and a current meter are additionally arranged in front of the interception net for detection and evaluation, but only indirect detection quantity can be obtained, and the state information of the blocking rate of the blocking net cannot be given. In addition, some nuclear power stations also use high-definition cameras of low-light-level imaging or infrared imaging technology to perform underwater optical detection, and the detection distance is limited because the penetrating power of visible light to the underwater environment is weak.

Patent CN207379640U discloses a nuclear power station is trash rack early warning alarm monitoring system under water, adopts the pulling force signal on the real-time main rope of gathering of plate ring formula force sensor at the main rope of trash rack, conveys long-range ground receiving terminal through the wireless emitter in waters, and the receiving terminal host computer carries out analytic judgement to the signal and makes corresponding early warning response of reporting to the police to combine the trash rack operating condition grade of supporting mutually, in time take measures to provide reliable foundation for nuclear power station intake cold source guarantee work group. According to the method, the state of the blocking net is tested by adopting the tension sensor, only indirect detection quantity can be obtained, and the state information of the blocking rate of the blocking net cannot be given.

Patent CN211784005U discloses an intercepting net tension on-line monitoring device in the technical field of nuclear power plant cold source safety, which comprises a current meter, wherein the current meter is electrically connected with a wireless transmission module for transmitting information, the wireless transmission module is respectively electrically connected with a tension sensor for detecting tension and a power supply module for providing power supply in an input mode, the wireless transmission module is electrically connected with a single chip microcomputer for analyzing and judging, the classification module is electrically connected with a storage module for storing information in an output mode, tension applied to the intercepting net is measured through the tension sensor in the device, and data is transmitted to a remote platform through the wireless transmission module, therefore, the operator can remotely monitor the interception net, when the acquired numerical value is greater than the standard numerical value, the alarm module sends an alarm to prompt the operator, the operator can know the abnormal condition of the interception net in time, and the using effect of the interception net is ensured. The patent also adopts the mode of tensile test to detect the jam condition of interception net, belongs to indirect detection, can not detect the jam rate state.

Disclosure of Invention

In order to solve the problems, the application provides a monitoring system and a monitoring method for the state of an interception net at a cold source water intake of a nuclear power station.

The first purpose of this application is to provide a nuclear power station cold source intake interception net state monitoring system, realizes monitoring, analysis and diagnosis to interception net jam state.

The second purpose of the application is to provide a method for monitoring the state of the intercepting net at the cold source water intake of the nuclear power station.

In order to achieve the purpose, the application provides a state monitoring system for a cold source water intake intercepting net of a nuclear power station, which comprises a wet end and a dry end,

the wet end is arranged underwater and comprises a sound wave transmitting module, a sound wave receiving module, a signal processing module and a communication module;

the sound wave transmitting module is used for transmitting a first sound wave signal;

the sound wave receiving module is used for receiving a first echo signal, and the first echo signal is a sound wave signal returned after the first sound wave signal contacts a target object;

the signal processing module is used for processing the first echo signal and generating corresponding stereo image information;

the sound wave transmitting module is also used for transmitting a second sound wave signal;

the sound wave receiving module is further used for receiving a second echo signal, wherein the second echo signal is a sound wave signal returned after the second sound wave signal contacts the target object;

the signal processing module is further used for calculating the flow velocity of water flowing through the target object according to the second echo signal;

the communication module is used for sending the stereo image information and the water flow velocity to the stem end;

the dry end is arranged on water and comprises a data processing module and a display module;

the data processing module is used for receiving the three-dimensional image information and the water flow velocity and calculating the blockage rate of the target object according to the three-dimensional image information and the water flow velocity;

the display module is used for displaying the blocking state of the target object.

Optionally, the sound wave emitting module includes a transmitter and a transmitting array,

the transmitter is configured to generate the first acoustic signal or the second acoustic signal;

the transmitting array is used for converting and transmitting the first sound wave signal or the second sound wave signal.

Optionally, the transmitting array is a single-channel spherical shell array.

Optionally, the acoustic wave receiving module includes a receiver and a receiving array,

the receiving array is a planar array and is used for receiving the first echo signal or the second echo signal and converting the first echo signal into a first electric signal or converting the second echo signal into a second electric signal;

the receiver is used for adjusting the first electric signal and converting the first electric signal into a first digital signal or adjusting the second electric signal and converting the second electric signal into a second digital signal.

Optionally, the receiving array includes a plurality of array elements, and the plurality of array elements are arranged in an array form.

The monitoring system for the state of the intercepting net at the cold source water intake of the nuclear power station utilizes sound waves to perform three-dimensional imaging on the underwater intercepting net, calculates the water flow velocity, obtains the blocking rate of the intercepting net by combining the three-dimensional imaging and the water flow velocity, and realizes monitoring, analysis and diagnosis of the blocking state of the intercepting net.

In order to achieve the second objective, the present application provides a method for monitoring the state of an intercepting net at a cold source water intake of a nuclear power plant, where the method is applied to the above system, and is characterized by comprising:

acquiring a first echo signal, and generating three-dimensional image information corresponding to a target object according to the first echo signal;

acquiring a second echo signal, and calculating the flow velocity of water flow according to the second echo signal;

and determining the blocking state of the target object according to the stereo image information and the water flow velocity.

Optionally, the obtaining a first echo signal, and generating stereoscopic image information corresponding to a target object according to the first echo signal includes:

transmitting a first sound wave signal through a sound wave transmitting module;

receiving the first echo signal, wherein the first echo signal is a sound wave signal returned after the first sound wave signal contacts the target object;

and converting the first echo signal into the stereo image information.

Optionally, converting the first echo signal into the stereoscopic image information includes:

converting the first echo signal into original point cloud image information;

extracting point cloud information in a predictive range from the original point cloud image information by using a denoising and segmentation algorithm;

separating and reconstructing the point cloud information to generate a plurality of target point cloud information;

and splicing the target point cloud information into the stereo image information by utilizing a registration splicing algorithm.

Optionally, determining the blockage state of the target according to the stereo image information and the water flow rate includes:

mapping the stereo image information and the water flow velocity to the same coordinate system;

acquiring a brightness value of the stereo image information, and normalizing the brightness value;

normalizing the water flow rate;

calculating the blockage rate of the target object according to the normalized brightness value and the normalized water flow velocity;

determining an occlusion status of the target object based on the occlusion rate.

Optionally, the method further includes:

and when the first echo signal does not meet the preset condition, performing phase compensation on the first echo signal.

Optionally, converting the first echo signal into original point cloud image information includes:

carrying out array element domain data rearrangement on the first echo signal;

calculating the rearranged first echo signal by using a planar array beam forming algorithm;

converting the first echo signal into a power signal by square detection;

and carrying out post-processing on the power signal.

Optionally, performing post-processing on the power signal includes:

carrying out non-coherent integration on the power signal to obtain distance information of each wave beam;

and selecting the maximum value of the distance information output of each beam, and restoring the maximum value into the original coordinate.

According to the monitoring method for the state of the intercepting net at the cold source water intake of the nuclear power station, the three-dimensional image information corresponding to the target object is formed by acquiring and analyzing the two echo signals, and the water flow velocity is calculated, so that the blocking rate of the intercepting net is obtained, and the monitoring, the analysis and the diagnosis of the blocking state of the intercepting net are realized.

Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application. In the drawings:

fig. 1 is a schematic structural diagram of a system for monitoring a state of an interception net at a cold source water intake of a nuclear power plant according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of a system for monitoring a state of an interception net at a cold source water intake of a nuclear power plant according to an embodiment of the present application;

fig. 3 is a schematic structural diagram of a monitoring system for a state of an intercepting net of a cold source water intake of a nuclear power plant according to an embodiment of the present application;

fig. 4 is a first flowchart of a method for monitoring a state of an intercepting net of a cold source water intake of a nuclear power plant according to an embodiment of the present application;

fig. 5 is a flowchart of a second method for monitoring a state of an intercepting net of a cold source water intake of a nuclear power plant according to an embodiment of the present application;

fig. 6 is a schematic flow chart of a method for monitoring a state of an intercepting net of a cold source water intake of a nuclear power plant according to an embodiment of the present application;

fig. 7 is a flowchart of a method for monitoring a state of an intercepting net of a cold source water intake of a nuclear power plant according to an embodiment of the present application;

FIG. 8 is a schematic diagram illustrating the effect of calculating the flow velocity of water flowing through a partition by using a broadband flow measurement method;

FIG. 9 is a flowchart of the echo signal conversion to a stereo image according to an embodiment of the present application;

fig. 10 is a flowchart of a post-processing method for monitoring a state of an intercepting net of a cold source water intake of a nuclear power plant according to an embodiment of the present application.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.

The system and the method for monitoring the state of the intercepting net of the cold source water intake of the nuclear power plant according to the embodiment of the application are described below with reference to the accompanying drawings.

As shown in fig. 1, the system for monitoring the state of the intercepting net at the water intake of the cold source of the nuclear power plant comprises a wet end 100 and a dry end 200.

The wet end 100 is arranged underwater and is mainly used for collecting and detecting signals of an underwater intercepting net; the dry end 200 is arranged on water and is mainly used for completing functions of data processing, man-machine interaction, graphic visualization and the like of acquired signals. The method specifically comprises image splicing and image recognition, and gives a blockage rate detection result by combining with water flow velocity comprehensive analysis, monitors the blockage state of the interception net, and sends out early warning information and the like.

The wet end 100 includes an acoustic transmitter module 110, an acoustic receiver module 120, a signal processing module 130, and a communication module 140.

The sound wave emitting module 110 emits a first sound wave signal, which propagates through the water, and is blocked after encountering a target object on the intercepting net, and the sound wave signal is reflected to form an echo signal. In this embodiment, the first acoustic wave signal may be a narrow band acoustic wave signal.

The acoustic wave receiving module 120 receives a first echo signal formed after the first acoustic wave signal contacts and reflects from the target object.

The signal processing module 130 is configured to process the first echo signal and generate corresponding stereoscopic image information. In this embodiment, the signal processing module 130 converts the echo signal into a stereo image through a beam forming algorithm, a pixel position in the image represents a position of an obstacle in water, and a brightness of the pixel represents an intensity of an acoustic wave reflected by the obstacle.

In addition, the acoustic wave emitting module 110 can also emit a second acoustic wave signal. The acoustic wave receiving module 120 may receive a second echo signal returned after the second acoustic signal contacts the target object. In this embodiment, the second acoustic signal may be a wideband encoded signal.

The signal processing module 130 calculates a flow rate of water flowing through the target object according to the second echo signal. In this embodiment, the signal processing module 130 calculates the second echo signal in a broadband flow measurement manner to obtain a flow velocity of water flowing through the target object.

The communication module 140 is configured to send the stereo image information and the water flow rate information formed by the signal processing module 130 to the dry end 200.

The dry end 200 includes a data processing module 210 and a display module 220. The data processing module 210 is configured to receive the stereo image information and the water flow rate, and calculate a blockage rate of the target object according to the stereo image information and the water flow rate; the display module 220 is used for displaying the blockage state of the target object.

The underwater sound wave signals are collected and analyzed to form a three-dimensional image of the intercepting net, the flow velocity of water flowing through a target object is obtained through calculation, the blocking rate of the intercepting net is obtained, the blocking state of the intercepting net is monitored in real time, and the monitoring accuracy is improved.

In one embodiment of this application, as shown in fig. 2, the acoustic wave transmission module 110 includes a transmitter 111 and a transmission array 112. The transmitter 111 is configured to generate a first acoustic signal or a second acoustic signal; the transmitting array 112 is used for converting and transmitting the first acoustic wave signal or the second acoustic wave signal. In this embodiment, the transmitting array 112 is a single-channel spherical shell array, for example, the operating frequency of the transmitting array may be 750kHz, so that a spherical acoustic radiation area is obtained.

In another embodiment of this application, as shown in fig. 3, the acoustic wave receiving module 120 includes a receiver 121 and a receiving array 122. The receiving array 122 is a planar array, and is configured to receive the first echo signal or the second echo signal, and convert the first echo signal into a first electrical signal or convert the second echo signal into a second electrical signal. The receiver 121 is configured to condition and convert the first electrical signal into a first digital signal or condition and convert the second electrical signal into a second digital signal. In this embodiment, the receiving array 122 includes a plurality of array elements, and the plurality of array elements are arranged in an array, for example, the plurality of array elements may be arranged in a 48 × 96 array.

The monitoring system for the state of the intercepting net at the cold source water intake of the nuclear power station provided by the embodiment monitors the blocking state of the intercepting net by using the sound wave signal, so that the anti-interference performance is strong, and the detection distance is long; the underwater sound wave signals are collected and analyzed to form a three-dimensional image, and the monitoring result is visual and clear; calculating the second echo signal by adopting a broadband flow measurement mode; the blocking rate of the interception net is comprehensively analyzed by combining the three-dimensional image and the water flow velocity, so that the monitoring accuracy is improved, and the real-time monitoring of the target object attachment process on the interception net body is realized.

In order to achieve the second purpose, the application also provides a method for monitoring the state of the intercepting net at the cold source water intake of the nuclear power station.

The method for monitoring the state of the intercepting net at the cold source water intake of the nuclear power station is applied to the system for monitoring the state of the intercepting net at the cold source water intake of the nuclear power station in the embodiment.

As shown in fig. 4, the method for monitoring the state of the intercepting net at the cold source water intake of the nuclear power station comprises the following steps:

step S1, acquiring the first echo signal, and generating stereoscopic image information corresponding to the target object according to the first echo signal.

In an embodiment of the present application, the obtaining the first echo signal and generating the stereoscopic image information corresponding to the target object according to the first echo signal may further include:

and S11, transmitting the first sound wave signal through the sound wave transmitting module.

In this embodiment, the first acoustic wave signal is a narrow band acoustic wave signal.

And S12, receiving the first echo signal.

The first echo signal is an acoustic signal returned after the first acoustic signal contacts the target object.

S13, converting the first echo signal into stereo image information.

Specifically, the first echo signal is converted into original point cloud image information, point cloud information in a prediction range is extracted from the original point cloud image information by using a denoising and segmentation algorithm, the point cloud information is separated and reconstructed, a plurality of target point cloud information is generated, and the target point cloud information is spliced into three-dimensional image information by using a registration and splicing algorithm.

Further, the method for converting the first echo signal into the original point cloud image information comprises the following steps:

the array element domain data rearrangement is carried out on the first echo signal, the rearranged first echo signal is operated by utilizing a planar array beam forming algorithm, then the square detection is adopted to convert the first echo signal into a power signal, and the post-processing is carried out on the power signal.

Wherein, post-processing the power signal comprises: and carrying out non-coherent integration on the power signal to obtain the distance information of each beam, then selecting the maximum value output by the distance information of each beam, and restoring the maximum value into the original coordinate.

And step S2, acquiring a second echo signal, and calculating the water flow velocity according to the second echo signal.

In one embodiment of the present application, the second acoustic signal may be transmitted by the acoustic wave transmitting module, and then the second echo signal may be received by the acoustic wave receiving module. The second echo signal is a sound wave signal returned after the second sound wave signal contacts the target object. After the second echo signal is received, the flow velocity of the water flowing through the intercepting net can be calculated in a broadband flow measuring mode.

In this embodiment, the second acoustic signal is a wideband encoded signal.

And step S3, determining the blockage state of the target object according to the stereo image information and the water flow velocity.

Specifically, the stereo image information and the water flow velocity may be mapped to the same coordinate system, then the luminance value of the stereo image information is obtained, the luminance value is normalized, then the water flow velocity is normalized, the blockage rate of the target object is calculated according to the normalized luminance value and the normalized water flow velocity, and finally the blockage state of the target object is determined based on the blockage rate.

In an embodiment of this application, as shown in fig. 5, the method for monitoring the state of the intercepting net at the water intake of the cold source of the nuclear power plant further includes:

and S4, when the first echo signal does not meet the preset condition, performing phase compensation on the first echo signal.

Wherein the preset condition is a far field condition, and the far field condition means that the target distance is greater than pi A²In the far field case of 4 λ, where a denotes the aperture length of the receiving array and λ denotes the signal wavelength. For example, the first echo signal does not satisfy the far field condition within a short distance range of 1-9.25 meters, and at this time, Fresnel phase compensation needs to be performed on the received first echo signal, and the first echo signal is converted into stereo image information after the phase compensation, so that the accuracy of the stereo image is improved.

The method for monitoring the state of the intercepting net at the water intake of the cold source of the nuclear power station is further described by a specific embodiment.

Fig. 6 is a schematic flow chart of a method for monitoring the state of an intercepting net at a cold source water intake of a nuclear power plant, wherein the method for monitoring the state of the intercepting net at the cold source water intake of the nuclear power plant mainly comprises the following steps:

s601, transmitting a narrow-band signal, S602, receiving a reflection signal, S603, carrying out three-dimensional imaging, and S604, carrying out post-processing on a three-dimensional image; s605 transmits a broadband signal, S606 receives a reflection signal, S607 flow velocity calculation, S608 carries out flow field splicing, and S609 forms a three-dimensional flow field. S610 comprehensively judges the processed stereo image and the water flow velocity calculation result, and S611 finally gives the blocking rate of the intercepting network.

The details can be seen in fig. 7.

Step S701, a specific narrowband acoustic wave signal is transmitted.

The transmitted signals are a group of narrow-band acoustic signals q (t), the signals propagate in an absorption medium with isotropic linear change, and the signals reaching a target scattering point through the propagation medium are obtained through FFT (fast Fourier transform), as shown in formula I:

wherein Q (ω) represents the FFT result of the transmission pulse signal Q (t); α (ω) represents an underwater acoustic wave absorption coefficient; ω 2 pi f, f denotes the transmitted signal frequency; and c represents the speed of sound.

Step S702 receives an echo signal of the transmitted specific narrowband acoustic wave signal.

After the sound wave transmission is finished, transmitting sound pulse signals q (t), after the sound pulse signals are reflected by scattering points, obtaining sound signals reaching a point p of a receiving array through FFT conversion, and obtaining the sound signals as shown in a formula II:

wherein, a_iRepresents the diameter of the scattering point; rho and rho_iRepresenting the density of the propagation medium and scatterers; k and k_iDenotes the compressibility of the propagation medium and scatterers; theta_iRepresents a vector (P-r)_i) And r_iThe angle therebetween.

Step S703, the echo signal is converted into a stereo image by a beam forming algorithm.

Step S704, a wideband coded signal is transmitted.

Step S705, an echo signal of the transmitted encoded acoustic wave signal is received.

And step S706, calculating the flow velocity of the water flowing through the intercepting net in a broadband flow measuring mode.

And step S707, the stereo image and the water flow velocity result are transmitted back to the data processing module of the dry end.

And step S708, comprehensively judging the stereo image and the water flow velocity result, and acquiring the blocking state of the blocking net.

For example, when the operating frequency of the transmitting array is 750kHz, the diameter of the rope of the intercepting net is 5mm, and the mesh width of the intercepting net is 2.5cm, the blockage state is judged by the intercepting net stereo image as follows: when no blockage exists on the intercepting net, the stereoscopic image of the intercepting net is displayed as discrete net noise, when the blockage on the intercepting net is gradually increased, the brightness displayed by the stereoscopic image of the intercepting net is gradually increased, but after the blockage is increased to a certain degree, the imaging result of the intercepting net is a discrete sheet, and when the blockage completely blocks meshes, the imaging result of the intercepting net is an integral sheet image with high brightness.

When the flow velocity of the water flow is calculated, the flow field of the whole area flowing through the intercepting net is partitioned, and the flow velocity of the water flow flowing through the partition can be calculated by adopting a broadband flow measurement mode. As shown in fig. 8, the three-dimensional imaging sonar is an array consisting of 96 × 48 array elements, the flow layer resolution thickness is 0.5m, the field angle is 45 ° × 45 °, the flow field angle resolution is 2 ° × 2 °, and the number of pixels output by the beam forming algorithm is 24 × 24. And taking any four beams symmetrical to the z axis, and assuming that the included angle between the axis of each beam and the z axis of the coordinate system of the flow measurement system is alpha.

Let the flow velocity column vector of a certain depth measurement layer unit under the array be v_dThe flow field of the measured area is considered to be uniform, namely the flow velocity and the direction of the water body measured at the same depth are the same. Three sonic wave beam measured flow velocity v_bCan be converted into a flow velocity vector v under the array_d. Wherein v is_b＝λ/2×Δf，v_d＝Bv_b. Δ f is the Doppler frequency offset vector, B is the transformation matrix.

In fact, the measured water body flow field is rarely completely uniform, that is, the flow velocity and direction of the measured water body on the same depth of the three-dimensional imaging sonar are different. Non-uniformity of the flow field introduces different degrees of flow rate inherent error. Compared with a three-beam Convex array structure, the four-beam Janus array structure can obtain more redundant information of the 4 th beam, so that the uniformity condition of a flow field can be verified. In order to quantify the influence caused by flow field nonuniformity, a flow rate inherent error formula can be introduced, which is an important factor for evaluating whether the data quality is effective.

The flow rate intrinsic error is formulated as: v. of_error＝v₁-v₂+v₃-v₄

It can be seen by analysis that, as long as the measured flow field is uniform, v is not influenced by the swing of the flow measuring system_errorAll are basically close to zero, and four echoes are regarded as valid data; if the measured flow field is not uniform, see also v_errorAnd determining the non-uniform degree, judging the effectiveness of the four-path echo data, judging the abnormal degree of the flow field and judging the blocking degree of the interception net.

The resolution of the flow field is 2 degrees of beam width, the flow measurement precision is 0.5 percent, and the transmitting signal is a coding sequence. The method adopts a broadband flow measurement mode to utilize coded coherent pulse train signals for receiving, transmitting and processing. Compared with a non-coherent flow measurement mode, the broadband flow measurement mode ensures that the speed estimation has higher precision by combining a high-resolution coding mode with flexible coherent measurement. Compared with a coherent stream measurement mode, the broadband stream measurement mode increases the energy of a signal through coding, so that a large measurable distance is ensured. This approach can therefore be viewed as a combination of non-coherent and coherent flow measurement.

The coded sequence is required to be transmitted independently during flow measurement, and the flow measurement and imaging are carried out in a time-sharing mode, different from single-frequency narrow pulses during imaging. The blocking objects of the interception net have corresponding relations with the flow velocity of the flow field, and when the blocking objects are increased, the flow velocity of the corresponding flow field is reduced. And superposing the flow field flow velocity and the imaging result of the interception net in the same coordinate system through three-dimensional space mapping and registration, and combining the flow field flow velocity and the imaging result of the interception net to obtain the blocking rate state of the interception net. The value range of the brightness value of the imaging result of the interception net is 0-L. Normalizing the brightness value of the imaging result of the intercepting net to obtain the highest brightness of 1, representing that the attachment degree of the blocking object is L at the highest, and the lowest brightness of 0, representing that the attachment degree is lowest; the flow field flow velocity is in the range of 0.1-S (unit m/S), the flow field flow velocity is normalized, the highest flow velocity (S m/S) is 1, and the lowest flow velocity is 0.1. The plugging rate index is L/S, and a higher index indicates a higher plugging rate.

As shown in fig. 9, the step S703 of converting the echo signal into the stereo image through the beamforming algorithm specifically includes:

step S801, analyzing the array element domain data type.

The invention adopts the broadband flow measurement mode to utilize the coded coherent pulse train signals for receiving, transmitting and processing, thereby ensuring that the speed estimation has higher precision and large measurable distance. Therefore, the signals in the array element domain need to be mixed and down-sampled before being processed in the next step. According to different functions, when three-dimensional imaging is carried out, a single-frequency pulse signal is emitted, a coding coherent pulse train signal is adopted during flow measurement, and after frequency mixing and down-sampling processing, serial-parallel conversion needs to be carried out on data.

Step S802, near field phase compensation.

Within a short distance range of 1-9.25 meters, the echo signal does not meet the far field condition (the far field condition means that the target distance is more than pi A)²In the far field case of 4 λ, where a denotes the aperture length of the receiving array and λ denotes the signal wavelength. ) Then, Fresnel phase compensation is needed to be performed on the received signal, as shown in equation three:

the underwater target has M scattering points, the ith scattering point is located at r_i＝(x_i,y_i,z_i) And at a distance r from the scattering point_i＝|r_iAnd l, the transmitted acoustic pulse signal is q (t), and after being reflected by scattering points, the acoustic signal reaching the p point of the receiving array is processed to obtain a signal, as shown in a formula four:

greater than π A for a target distance²The far-field condition at 4 λ, the received signal of the far-field condition is obtained as shown in equation five:

wherein the content of the first and second substances,fixed parameter delta²Representing the influence of the medium absorption coefficient, Q (omega) represents the FFT result of the emission pulse signal Q (t); ω 2 pi f, f denotes the transmitted signal frequency; and c represents the speed of sound.

In step S803, the array element field data is rearranged.

The system has 4608 array elements (96 multiplied by 48), the genetic algorithm is adopted to carry out sparse processing on the planar array, and 1024 array elements in the planar array are selected to participate in imaging processing. Before the planar array beam is formed, the array element data sequence is rearranged to recover the original position.

Step S804, a planar array beam is formed.

And (3) performing frequency domain beam forming by using a beam forming algorithm and two-dimensional fast Fourier transform to form 128 multiplied by 128 paths of planar array beams which are 16384 in total.

Step S805, square detection.

The beamformed signal is a complex signal and needs to be squared and detected to be a power signal.

And step 806, post-processing.

In this embodiment, as shown in fig. 10, the post-processing includes the following steps:

step S901, denoising and segmenting.

And extracting the target point cloud within a certain distance range from the huge original point cloud through a denoising and partitioning algorithm to obtain a simplified point cloud and remove abnormal points.

And step S902, point cloud reconstruction.

And reconstructing the obtained point cloud to realize the separation reconstruction of a plurality of targets.

And step S903, registration and splicing.

And merging and unifying the point clouds obtained from all visual angles or multiple frames to a coordinate system through a registration and splicing algorithm to form a complete point cloud.

And step S904, visualization rendering.

Through the visualization rendering process, graphics for UI display are generated.

According to the method for monitoring the state of the intercepting net at the cold source water intake of the nuclear power station, the blocking state of the intercepting net is monitored by collecting and analyzing the sound wave signals, so that the interference resistance is strong, and the detection distance is long; the underwater sound wave signals are collected and analyzed to form a three-dimensional image, and the monitoring result is visual and clear; calculating the second echo signal by adopting a broadband flow measurement method; the blocking rate of the interception net is comprehensively analyzed by combining the three-dimensional image and the water flow velocity, so that the monitoring accuracy is improved, and the real-time monitoring of the target object attachment process on the interception net body is realized.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The logic and/or steps represented in the flowcharts or otherwise described herein, e.g., an ordered listing of executable instructions that can be considered to implement logical functions, can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory.

It should be understood that portions of the present application may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.

It should be noted that in the description of the present specification, reference to the description of the term "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.