CN104092308A - Transmission tower online safety monitoring system and method for stress measuring - Google Patents

Abstract

The invention belongs to the field of power system overhead transmission line tower safety monitoring, and provides a transmission tower online safety monitoring system and method for stress measuring. Firstly, stress sensors are installed on the key parts of a tower, and installation points can be obtained through finite element analysis and load application. Measurement values of the stress sensors are transmitted to a background server through the internet, the background server works out the reliability of each section of main material in real time according to each group of data together with the mean value and the variance of the strength of steel materials, and therefore the overall reliability of the tower can be obtained. The transmission tower online safety monitoring system and method have the following advantages that the problem of real-time tower stress monitoring is solved, and the stress distribution situations of the key parts can be monitored in real time; the safety state of the tower can be estimated in real time and serious accidents such as collapse can be effectively prevented under severe working conditions; research results are wide in application and can be directly applied to various tower shapes.

Description

The electric power pylon on-line monitoring system and method that a kind of stress measures

Technical field

The invention belongs to electric power system iron towers of overhead power transmission lines security monitoring field, be specifically related to the electric power pylon on-line monitoring system and method that a kind of stress measures

Background technology

Due to recent years electric power line failure, the Frequent Accidents such as tower that falls, on the circuit that particularly line ice coating is thicker in the winter time, broken string, the probability of tower of falling are higher.Under extreme disaster scenarios it, cause especially a large amount of collapse of iron towers, the safe operation of electrical network is caused to great impact, the ice damage as 2008 just causes the collapse of south electric network large area.The generation that how to prevent such accident is the emphasis of paying close attention to and studying always.For Transmission Tower-line system, the stress distribution situation of steel tower has reflected the safe condition of tower system the most intuitively, and the reason root of collapsing or being out of shape of power transmission tower has exceeded the steel strength of steel tower in the stress of steel tower failure site.Meanwhile, the stress of steel tower has not only directly reflected the load condition of steel tower sheet material, also reflected simultaneously comprise lead, the tower architecture situation of ground wire etc.

Because tower material is in the situation that being subject to external force, tower material itself can produce stress deformation to a certain degree.Under normal conditions, this deformation extent is difficult to directly observe, but can measure the deflection on this microcosmic by ess-strain equipment, and then determines the stressing conditions of this tower material.Measure by the dependent variable to key position on iron tower structure, obtain the stressing conditions of different parts, and then judge the overall stressing conditions of this steel tower.By the continuous monitoring to this steel tower stressing conditions, can obtain the stressed situation of change of steel tower, analyze the stressed peak value of steel tower, and with the design Force Calculation value comparison of steel tower, the real time security situation of assessment steel tower.

Summary of the invention

The present invention solves the existing technical problem of prior art; A kind of stress distribution of real-time demonstration steel tower is provided, and the reliability of each section of main material, and the electric power pylon on-line monitoring system and method for a kind of stress measurement showing intuitively on interface.

It is to solve the existing technical problem of prior art that the present invention also has an object; A kind of different turriform that adapts to is provided, and robustness is good, has the electric power pylon on-line monitoring system and method for a kind of stress measurement of good autgmentability.

It is to solve the existing technical problem of prior art that the present invention has an object again; Provide one to there is warning function, when reliability is during lower than certain amount, can send warning, be convenient to the electric power pylon on-line monitoring system and method that a kind of stress that operations staff processes measures.

Above-mentioned technical problem of the present invention is mainly solved by following technical proposals:

The electric power pylon on-line monitoring system that stress measures, is characterized in that, comprising:

Some strain gauges: be arranged on steel tower, for measuring the stressing conditions of the residing steel tower of strain gauge position;

A front-end collection processor: the data of strain gauge are carried out to acquisition process, and proofread and correct, encode after calculating stress, and by wireless network, the transfer of data after coding is gone out;

A background server: the data of receiving front-end Acquisition Processor transmission, and carry out analytical calculation, and in the time that reliability exceedes user and sets amount, send warning.

A method for the electric power pylon on-line monitoring system that applied stress measures, is characterized in that,

Comprise the following steps:

Step 1, background server carries out main material reliability and calculates: the statistical law Normal Distribution of the steel yield strength R of electric power pylon; The stress data collecting is distributed as their asymptotic normality by corresponding normal distribution or logarithm normal distribution, carry out equivalent normalize by stochastic variable; At regular intervals, the strain gauge of installing from N main material is obtained the data that N group is measured at a high speed to definition hypothesis, and every group of data have M, obtain its average u for every group of data _iand variances sigma _i, for: (u ₁, σ ₁), (u ₂, σ ₂) ..., (u _n, σ _n).

Arbitrary section of main material reliability β _idrawn by following formula:

${\mathrm{\β}}_i=\frac{u_Z}{{\mathrm{\σ}}_Z}=\frac{u_i-u_S}{\sqrt{{\mathrm{\σ}}_i^2+{\mathrm{\σ}}_S^2}}$

Step 2, background server carries out the calculating of steel tower reliability: calculate respectively after the reliability of each main material section, the minimum value in this N reliability is the reliability of steel tower, and this reliability value is electric power pylon safety on line and detects metric.

The method of the electric power pylon on-line monitoring system measuring at above-mentioned a kind of applied stress, the concrete grammar of the virtual branch that is arranged on the strain gauge on steel tower solid finite element model comprises the following steps:

Step 1, for monitored transmission of electricity turriform structural parameters, carry out finite element mechanical modeling, concrete mode is the cad file according to this steel tower, and build design data when steel tower, set up the solid finite element model of steel tower based on large commercial finite element module, the size of model each several part is according to the parameter in design data, and material parameter when initial modeling is according to specification value; Wherein, the each rod member of power transmission tower all adopts the BEAM188 beam element simulation of custom cross section shape;

Step 2, load is chosen: for the residing geographical position of steel tower and operational environment, add consider wind load choose object as load; , due to the wind load of having obtained in solid finite element model structure everywhere, Structure Calculation just can be undertaken by static(al) method;

Step 3, the solid finite element model of the steel tower of setting up for step 1 and the load that step 2 is chosen are carried out model analysis; Calculating in the empirical equation of wind vibration factor, need to know the background component factor of wind loads, wherein need to use the 1st rank natural frequency of vibration; Adopt Block Lanczos method to carry out model analysis to this tower total, can obtain the 1st rank natural frequency of vibration of structure:

Power transmission tower Wind load calculating formula:

w＝β _zμ _sμ _zw ₀

Wherein, β _zfor consider the wind vibration factor of wind pressure pulsation impact that structure generation is aweather shaken with the wind; μ _sfor Shape Coefficient, can check according to specification; μ _zfor height variation coefficient of wind pressure, can show that according to this formula the wind load of steel tower distributes.

Step 4, the power transmission tower Wind-load Analysis obtaining according to step 3 is also calculated extremum stress: apply after wind load, utilize the bending stress of finite element module calculating axial stress and Y, Z direction (unit local coordinate).Then be combined in the following way the extremum stress of each each unit:

Stress one: Y-direction top, cross section extremum stress=axial stress+Y-direction upper bend stress;

Stress two: Y-direction bottom, cross section extremum stress=axial stress+Y-direction lower knuckle stress;

Stress three: Z-direction top, cross section extremum stress=axial stress+Z-direction upper bend stress;

Stress four: Z-direction bottom, cross section extremum stress=axial stress+Z-direction lower knuckle stress.

Step 5, determine strain gauge position according to the stress distribution situation of main material and oblique material: the maximum stress specifically drawing in step 4, respectively to the stress value sequence in main material and oblique material stress envelope, obtain the strain gauge number how many foundations of the point N of top n stress maximum will install and determine, wherein tiltedly material, owing to not being major bearing structures, only calculates main material stress distribution situation.

Therefore, tool of the present invention has the following advantages:: 1. can show in real time the stress distribution of steel tower, and the reliability of each section of main material, and show intuitively on interface; 2. adapt to different turriforms, robustness is good, has good autgmentability; 3. there is warning function, when reliability is during lower than certain amount, can send warning, be convenient to operations staff and process.

Brief description of the drawings

Accompanying drawing 1 is a kind of system configuration principle schematic of the present invention.

Accompanying drawing 2 is strain gauge scheme of installations of the present invention.

Accompanying drawing 3 is the power transmission tower steel construction FEM (finite element) model figure that the present invention relates to.

Accompanying drawing 4 is main material stress cloud atlas in the embodiment of the present invention.

Embodiment

Below by embodiment, and by reference to the accompanying drawings, technical scheme of the present invention is described in further detail.

Embodiment:

One, paper system and method involved in the present invention:

(1) Solution Architecture.

System is made up of strain gauge, front-end collection processor and background server.Front-end collection processor is responsible for the data of strain gauge to carry out acquisition process, proofreaies and correct in conjunction with factors such as temperature, encodes after calculating stress, passes to background server.Front-end collection processor adopting DSP framework, uses GPRS/CDMA data network and background server to communicate.Whole system framework as shown in Figure 1.

Between data acquisition unit and Data Centralized Processing device, connect communication by 485 interfaces.Data acquisition unit is delivered the data that collect to focus on device processing, focus on device by data change, by protocol packing, send to daemon software.Meanwhile, Data Centralized Processing device receives the order on backstage, operates accordingly.Data Centralized Processing device communicates by GPRS/CDMA DTU and backstage, the data of Data Centralized Processing device output are sent to the serial ports of DTU modem, then after the encapsulation of DTU agreement, become Ethernet data, issue background server by GPRS/CDMA data network.

On-site data gathering subsystem device is realized the collection of stress data, temperature data.This system comprises signal transducer unit, signal gathering unit and power-supply unit composition.Strain gauge adopts vibrating string type sensor, and certainty of measurement is ± 0.1%FS that measuring range (stretching/compressing, dimension is 10-6) is 1500/1700, carries temperature correction function.Scheme of installation as shown in Figure 2.

Daemon software is realized 3 large functions, first, complete with remote data acquisition module communicate by letter and mutual; Two, the demonstration of data and storage; Three, data analysis function.Database is based on SqlServer platform, and program is used Java exploitation.

Because system need to continually be worked in the wild, therefore system front end adopts solar powered, in order to save electric power, system works can be operated in various modes, comprise timing load mode state, transmission gathers transmission primaries data at set intervals, and while not transmitting data, system is in resting state.

(2) installation of sensors point.

According to the cad file of steel tower, and build design data when steel tower, utilize finite element software ANSYS to set up the solid finite element model of steel tower, then load application, obtain the point that stress value is larger, be candidate's mounting points, specifically in other patent, be otherwise noted.

(3) calculating of reliability.

Steel tower is made up of numerous main materials, auxiliary material and oblique material etc., owing to being mainly the yield failure of main material in the time that steel tower lost efficacy, can be reduced under study for action the surrender inefficacy Reliability Solution to main material member structure.The main material hop count playing a major role under normal operation is 3～5.Because every 1 main material segmentation is made up of 4 main materials, these four main materials, in symmetrical, are subject to same limit state equation control, can think that failure mode is the same.Therefore, for transmission tower structure, the failure mode number under normal operation is 3～5.Wherein the inefficacy of arbitrary main material section all will cause the inefficacy of total system.Be that steel tower reliability is minimum main material reliability.That is:

$P_s=P(\underset{1\≤i\≤N}{\min }{Z}_i>0)---\left(1\right)$

In above formula: Ps is steel tower reliability, P (Zi) is the reliability of i main material section.

4) main material reliability computational process.

If the R of transmission tower rod member and S are randoms variable of continuous type, separate and Normal Distribution, also Normal Distribution of Z, its average and standard deviation are respectively:

$u_Z=u_R-u_S,{\mathrm{\σ}}_Z=\sqrt{{\mathrm{\σ}}_R^2+{\mathrm{\σ}}_S^2}$

Its distribution density function is:

$F_Z\left(Z\right)=\frac{1}{{\mathrm{\σ}}_Z\sqrt{2\mathrm{\π}}}\underset{-\∞}{\overset{Z}{\∫}}\exp [-\frac{1}{2}{\left(\frac{Z-u_Z}{{\mathrm{\σ}}_Z}\right)}^2]---\left(3\right)$

The failure probability of structure is

$P_f=P\{z<0\}=F_Z\left(0\right)=\mathrm{\&Phi;}\left[\frac{Z-u_Z}{{\mathrm{\&sigma;}}_Z}\right]---\left(4\right)$

The RELIABILITY INDEX β of structure can be drawn by following formula:

$\mathrm{\&beta;}=\frac{u_Z}{{\mathrm{\&sigma;}}_Z}=\frac{u_R-u_S}{\sqrt{{\mathrm{\&sigma;}}_R^2+{\mathrm{\&sigma;}}_S^2}}---\left(5\right)$

And P _f=Φ [β], or β=Φ ^-1(1-P _f) (6)

This computing formula is to be all that normal distribution is derived based on R and S.In this steel tower online evaluation system, the statistical law of the steel Q235 of electric power pylon and the yield strength R of Q345 can be thought Normal Distribution.Measure the whether Normal Distribution of distribution of stress value S for steel tower, there is no at present correlative study final conclusion, even if but S is while being Non-Gaussian Distribution, available corresponding normal distribution or logarithm normal distribution distribute as their asymptotic normality, carry out equivalent normalize by stochastic variable.

(5) result of steel tower reliability.

Calculate respectively after the reliability of each main material section, can utilize formula (1) to obtain the reliability of steel tower.So just complete online evaluation.

Two, be below a concrete case that adopts said method:

Step 1, steel tower is carried out to finite element modeling, apply specific load, obtain the main material stress cloud atlas of steel tower.Fig. 1 is the FEM (finite element) model of certain cat owl tower, and tower height overall is 48.5 meters, its main material Q345 steel, and all the other materials are Q235 steel, density of material is ρ=7850kg/m ³, elastic modulus E=2.06 × 10 ⁵mPa, by load code, structural damping ratio ξ=0.01 of steel construction.Each rod member is L-type section form; Y axle is vertical, and z axle is for hanging wire direction.The equal three-dimensional beam element BEAM188 in all unit in Fig. 2.This model has 513 nodes, 1298 beam element numbers, and tower is affixed with basis, and supposes that material is in the elastic working stage.This tower site condition is category-A landforms, and basic wind speed is v ₀=30m/s.

Determining of step 2, strain gauge mounting points.

Consider wind load, obtain the stress cloud atlas of steel tower, as shown in Figure 4.Choose 607 unit aspects, 604 unit aspects, 603 unit aspects as monitored object.Because the tension and compression stress maximum that these 3 aspects are subject to.4 strain gauges of the symmetrical installation of each aspect.Strain gauge adopts vibrating string type sensor, and when installation, symmetry is arranged on four main materials that are welded on steel tower.

Step 3, reliability are calculated.

Suppose (as 10 minutes) at regular intervals, the strain gauge of installing from 12 main materials is obtained 12 groups of data, obtains its average u respectively for every group of data _iand variances sigma _i, for: (u ₁, σ ₁), (u ₂, σ ₂) ..., (u ₁₂, σ ₁₂).Owing to being only concerned about surrender inefficacy here, only consider that measured value is the compression of negative value.Then calculate according to formula (5).In formula (5), the average of the yield strength of steel and variance can be found by table 1, and, for i main material, its reliability is:

${\mathrm{\&beta;}}_i=\frac{u_i-u_S}{\sqrt{{\mathrm{\&sigma;}}_i^2+{\mathrm{\&sigma;}}_S^2}}$

For one group of stress value, result of calculation is as shown in table 2.

The yield strength statistical parameter of table 1 Q345 steel

Table 2 reliability is calculated

step 4, ask steel tower total reliability.

As can be drawn from Table 2, minimal reliability is 4.24, and according to " steel tower total reliability is determined by its little main material reliability " criterion, this moment steel tower entire system reliability is 4.24.

Step 5, at set intervals, received primary stress as ten minutes, calculated thereby repeating step 3. has completed the real-time reliability of electric power pylon.

Specific embodiment described herein is only to the explanation for example of the present invention's spirit.Those skilled in the art can make various amendments or supplement or adopt similar mode to substitute described specific embodiment, but can't depart from spirit of the present invention or surmount the defined scope of appended claims.

Claims (3)

1. the electric power pylon on-line monitoring system that stress measures, is characterized in that, comprising:

Some strain gauges: be arranged on steel tower, for measuring the stressing conditions of the residing steel tower of strain gauge position;

A front-end collection processor: the data of strain gauge are carried out to acquisition process, and proofread and correct, encode after calculating stress, and by wireless network, the transfer of data after coding is gone out;

A background server: the data of receiving front-end Acquisition Processor transmission, and carry out analytical calculation, and in the time that reliability exceedes user and sets amount, send warning.

2. right to use requires a method for the electric power pylon on-line monitoring system of the stress measurement described in 1, it is characterized in that, comprises the following steps:

Step 1, background server carries out main material reliability and calculates: the statistical law Normal Distribution of the steel yield strength R of electric power pylon; The stress data collecting is distributed as their asymptotic normality by corresponding normal distribution or logarithm normal distribution, carry out equivalent normalize by stochastic variable; At regular intervals, the strain gauge of installing from N main material is obtained the data that N group is measured at a high speed to definition hypothesis, and every group of data have M, obtain its average u for every group of data _iand variances sigma _i, for: (u ₁, σ ₁), (u ₂, σ ₂) ..., (u _n, σ _n);

Arbitrary section of main material reliability β _idrawn by following formula:

${\mathrm{\&beta;}}_i=\frac{u_Z}{{\mathrm{\&sigma;}}_Z}=\frac{u_i-u_S}{\sqrt{{\mathrm{\&sigma;}}_i^2+{\mathrm{\&sigma;}}_S^2}}$

Step 2, background server carries out the calculating of steel tower reliability: calculate respectively after the reliability of each main material section, the minimum value in this N reliability is the reliability of steel tower, and this reliability value is electric power pylon safety on line and detects metric.

3. the method for the electric power pylon on-line monitoring system that a kind of applied stress according to claim 1 measures, is characterized in that, the concrete grammar of the virtual branch that is arranged on the strain gauge on steel tower solid finite element model comprises the following steps:

Step 1, for monitored transmission of electricity turriform structural parameters, carry out finite element mechanical modeling, concrete mode is the cad file according to this steel tower, and build design data when steel tower, set up the solid finite element model of steel tower based on large commercial finite element module, the size of model each several part is according to the parameter in design data, and material parameter when initial modeling is according to specification value; Wherein, the each rod member of power transmission tower all adopts the BEAM188 beam element simulation of custom cross section shape;

Step 2, load is chosen: for the residing geographical position of steel tower and operational environment, add consider wind load choose object as load; Due to the wind load of having obtained in solid finite element model structure everywhere, Structure Calculation just can be undertaken by static(al) method;

Step 3, the solid finite element model of the steel tower of setting up for step 1 and the load that step 2 is chosen are carried out model analysis; Calculating in the empirical equation of wind vibration factor, need to know the background component factor of wind loads, wherein need to use the 1st rank natural frequency of vibration; Adopt Block Lanczos method to carry out model analysis to this tower total, can obtain the 1st rank natural frequency of vibration of structure:

Power transmission tower Wind load calculating formula:

w＝β _zμ _sμ _zw ₀

Wherein, β _zfor consider the wind vibration factor of wind pressure pulsation impact that structure generation is aweather shaken with the wind; μ _sfor Shape Coefficient, can check according to specification; μ _zfor height variation coefficient of wind pressure, can show that according to this formula the wind load of steel tower distributes;

Step 4, the power transmission tower Wind-load Analysis obtaining according to step 3 is also calculated extremum stress: apply after wind load, utilize the bending stress of finite element module calculating axial stress and Y, Z direction (unit local coordinate); Then be combined in the following way the extremum stress of each each unit:

Stress one: Y-direction top, cross section extremum stress=axial stress+Y-direction upper bend stress;

Stress two: Y-direction bottom, cross section extremum stress=axial stress+Y-direction lower knuckle stress;

Stress three: Z-direction top, cross section extremum stress=axial stress+Z-direction upper bend stress;

Stress four: Z-direction bottom, cross section extremum stress=axial stress+Z-direction lower knuckle stress;

Step 5, determine strain gauge position according to the stress distribution situation of main material and oblique material: the maximum stress specifically drawing in step 4, respectively to the stress value sequence in main material and oblique material stress envelope, obtain the strain gauge number how many foundations of the point N of top n stress maximum will install and determine, wherein tiltedly material, owing to not being major bearing structures, only calculates main material stress distribution situation.