CN111561964A - Random simulation method and test platform for outdoor axial temperature distribution characteristics of overhead conductor - Google Patents
Random simulation method and test platform for outdoor axial temperature distribution characteristics of overhead conductor Download PDFInfo
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Abstract
The invention discloses a random simulation method and a test platform for outdoor axial temperature distribution characteristics of an overhead conductor. The method comprises the following steps: step 1: constructing an outdoor axial temperature distribution calculation model of the overhead conductor; step 2: the method comprises the steps of building an overhead conductor outdoor axial temperature distribution characteristic test platform, acquiring monitoring data of experimental conductor axial temperature distribution and surrounding meteorological environment through the overhead conductor outdoor axial temperature distribution characteristic test platform, simulating conductor axial temperature distribution by utilizing the monitoring data in combination with a temperature calculation model, and further obtaining conductor axial temperature distribution characteristics under different current levels and outdoor random meteorological conditions. According to the invention, the axial temperature distribution characteristics of the wires under outdoor random meteorological conditions and different current levels are simulated according to the historical data measured by the test platform, so that the wire temperature distribution data which is more in line with actual change is provided for line operation safety assessment and power grid analysis, and the reliability of the line safety assessment and the power grid analysis is favorably improved.
Description
Technical Field
The invention belongs to the technology of dynamic simulation of the temperature of an overhead conductor, and particularly relates to a random simulation method and a test platform for the outdoor axial temperature distribution characteristic of the overhead conductor.
Background
With the development of economy and the improvement of the requirements of people on living quality, the demand of electric power is larger and larger, and the quality requirement on the supply of electric power to a power supply department is higher, so that the stable operation of a power grid of a remote transmission line is very important. The temperature of the wire of the overhead transmission line is an important parameter for the operation of the transmission and distribution line. When the axial temperature distribution of the overhead transmission line conductor is not uniform, the reliability of the transmission line safety evaluation and power grid analysis method can be influenced. The temperature of the overhead transmission line conductor along the axial direction is mostly caused by the rapid change or uneven distribution of weather under the space-time scale. Even when the ambient weather variation along the line is small, wire breakage due to fatigue or aging of the line can cause axial temperature distribution of the wire. In addition, power fittings and other mounted auxiliary equipment can also cause the overhead conductor to generate axial temperature distribution. In order to research the axial temperature change of the overhead conductor under outdoor random meteorological conditions, a test platform for the axial temperature distribution characteristic of the overhead transmission line conductor needs to be established, and the rule and the characteristic of the axial temperature distribution of the overhead transmission line conductor are searched. Therefore, the test platform is set up to monitor the axial temperature distribution of the overhead transmission line conductor in real time, so that the axial temperature rise curves of the conductor under different meteorological and current levels can be obtained, key data are provided for the line operation safety assessment and the power grid analysis method, faults can be effectively prevented, and the safety and reliability of power grid transmission are improved.
In recent years, domestic power grids have many accidents caused by abnormal temperature states of overhead power transmission lines, so that various research institutions carry out a great deal of research on the state analysis theory of the overhead power transmission lines and the design of a wire experiment platform. The invention discloses a Chinese invention patent with the application publication number of CN 110361577A, namely an experimental platform and a method for evaluating the risk of single-phase disconnection and grounding faults of a power transmission line, and discloses an experimental platform capable of effectively simulating and inverting the single-phase disconnection and grounding faults of the power transmission line, but the experimental platform aims at the single-phase disconnection and grounding faults of the power transmission line and does not research the temperature change of a lead of the power transmission line. The application publication number is "CN 209182407U" Chinese utility model patent "verifies the experiment platform that the maximum current-carrying capacity of carbon-fibre composite core wire calculated the accuracy", discloses an experiment platform that verifies the maximum current-carrying capacity of carbon-fibre composite core wire and calculates the accuracy. Although the experiment platform can monitor the operating temperature of the wire, the experiment platform considers the wire as an isothermal body and only measures the single-point temperature change of the wire. The invention relates to a method for randomly simulating the outdoor axial temperature distribution characteristics of overhead transmission line conductors, which can simulate the outdoor random meteorological conditions and the axial temperature distribution characteristics of the overhead conductors under different current levels according to historical data measured by a test platform, and provides conductor temperature distribution data which are more in line with actual changes for a line operation safety evaluation and power grid analysis method.
Disclosure of Invention
The invention aims to provide a random simulation method and a test platform for outdoor axial temperature distribution characteristics of an overhead conductor, which solve the problem that the prior art cannot simulate the outdoor random meteorological conditions and the axial temperature distribution characteristics of the conductor under different current levels according to historical data measured by the test platform.
The technical solution for realizing the purpose of the invention is as follows: a random simulation method and a test platform for outdoor axial temperature distribution characteristics of an overhead conductor comprise the following steps:
step 1: constructing an outdoor axial temperature distribution calculation model of the overhead conductor;
step 2: the method comprises the steps of building an overhead conductor outdoor axial temperature distribution characteristic test platform, obtaining monitoring data of experimental conductor axial temperature distribution and surrounding meteorological environment through the overhead conductor outdoor axial temperature distribution characteristic test platform, simulating conductor axial temperature distribution by utilizing the monitoring data in combination with a temperature calculation model, and further obtaining conductor axial temperature distribution characteristics under different current levels and outdoor random meteorological conditions.
An outdoor axial temperature distribution characteristic test platform for an overhead conductor comprises a large current generator, a splicing sleeve, a support frame, a heating device, a CT power supply, a current transformer, a conductor temperature sensor group, an environment temperature sensor group, a micro meteorological station, a wireless data acquisition device, an upper computer and a plurality of lifting ropes; the heating device is arranged on an overhead conductor to be tested and used for forming a local hot spot on the overhead conductor so as to generate axial temperature distribution on the overhead conductor under outdoor random meteorological conditions, the conductor temperature sensor group comprises a plurality of temperature sensors and is arranged on the overhead conductor and used for measuring the axial temperature distribution of the overhead conductor, the environment temperature sensor group comprises 2 temperature sensors, one temperature sensor is arranged in the heating device, the other temperature sensor is arranged outside the heating device and is used for respectively measuring the environment temperature in the heating device and the environment temperature outside the heating device; the overhead conductor is connected end to end through the splicing sleeve to form an annular current loop, the overhead conductor is fixed on the support frame in a suspension mode through a plurality of lifting ropes, a large current generator is used for generating current and is located under the overhead conductor, the current generated by the overhead conductor is coupled to the overhead conductor, a CT power supply and a current transformer are arranged on the overhead conductor and are respectively connected with the wireless data acquisition device, the miniature weather station comprises a wind speed and wind direction sensor and a solar radiation sensor and is fixed on the support frame, the wind speed and wind direction sensor and the solar radiation sensor are respectively connected with the wireless data acquisition device, and the wireless data acquisition device transmits monitoring data to the PC of the upper computer.
Compared with the prior art, the invention has the remarkable advantages that: based on the division of the boundary infinitesimal and the non-boundary infinitesimal of the wire, the historical data measured by the test platform for the axial temperature distribution characteristic of the overhead wire is utilized to carry out random simulation, and the axial temperature distribution characteristic of the wire under outdoor random meteorological conditions and different current levels can be obtained.
Drawings
Fig. 1 is a schematic flow chart of an outdoor axial temperature distribution characteristic random simulation method for an overhead transmission line conductor of the invention.
Fig. 2 is a schematic diagram of the axial micro-element division of the overhead conductor of the present invention.
Fig. 3 is a schematic structural diagram of an outdoor axial temperature distribution characteristic test platform of the overhead conductor of the invention.
Fig. 4 is a block diagram of a wireless data acquisition device according to the present invention.
Fig. 5 is a schematic view of the heating device of the present invention.
Fig. 6 is a schematic diagram of the installation position of the wire temperature sensor group according to the present invention.
Detailed Description
The present invention is described in further detail below with reference to the attached drawing figures.
Referring to fig. 1, a method for randomly simulating outdoor axial temperature distribution characteristics of an overhead conductor includes the following steps:
step 1: the method for constructing the outdoor axial temperature distribution calculation model of the overhead conductor specifically comprises the following steps: :
in the step 1, an outdoor axial temperature distribution calculation model of the overhead conductor is constructed,
step 1-1) as shown in fig. 2, the overhead conductor 1 to be measured is equally divided along the radial direction to obtain axial micro-elements of the conductor with the same length.
Step 1-2) dividing the obtained axial micro-elements of the wire into boundary micro-elements and non-boundary micro-elements as shown in fig. 2; the boundary infinitesimal refers to the infinitesimal where the boundary temperature is located; and non-boundary elements refer to elements other than wire boundary elements; in engineering, the wire sections with more uniform meteorological distribution or the wire sections without connecting hardware fittings nearby are used as boundary infinitesimal elements; the heat balance equation of the wire of the boundary infinitesimal is as follows:
t in formula (1) is time; t iscThe operating temperature of the wire; c is the equivalent heat capacity of the lead; q. q.sJ、qs、qcAnd q isrRespectively the heat power generated by the current of the conducting wire, the sunlight heat absorption power, the radiation heat dissipation power and the convection heat dissipation power.
The wire thermal equilibrium equation for the non-boundary infinitesimal is:
in the formula (2), i represents the ith infinitesimal, and similarly, i-1 represents the i-1 st infinitesimal; t isc，iThe operating temperature of the wire infinitesimal i; ciThe equivalent heat capacity of the lead wire micro element i; q. q.sJ，i、qs，i、qc，iAnd q isr，iRespectively generating thermal power, sunlight heat absorption power, radiation heat dissipation power and convection heat dissipation power for the wire infinitesimal i current; q. q.sd，i-1The thermal power is conducted from the lead micro element i-1 to the micro element i; q. q.sd，iThe thermal power conducted from the wire micro-element i to the micro-element i + 1.
Step 1-3) performing hot circuit model equivalence on the formula (1) and the formula (2) comprises the following steps:
r in the formula (3)cIs the equivalent convective thermal resistance of the overhead conductor; t iseAmbient temperature around the overhead conductor;
t in formula (4)c，i-1The operating temperature is the wire infinitesimal i-1 operating temperature; t isc，i+1The operating temperature is the wire infinitesimal i + 1; rdmIs the conduction thermal resistance of the wire infinitesimal i; cmThe equivalent heat capacity of the lead wire micro element i; rc，iIs equivalent convective thermal resistance of the wire infinitesimal i; t ise，iIs the ambient temperature around the wire infinitesimal i.
Step 1-4), when the parameters of the overhead conductor and the external environment parameters are known, combining the initial temperature of the overhead conductor, calculating the axial temperature distribution of the conductor at any time by utilizing an outdoor axial temperature distribution calculation model of the overhead conductor, wherein the conductor temperature of a boundary infinitesimal and a non-boundary infinitesimal of the conductor at a time k is represented as follows:
in the formula (5), k is time; similarly, k-1 is the last moment; Δ t is the time interval between two moments;
the operating temperature of the wire at the moment k;
the operating temperature of the wire at the moment k-1;
and
respectively generating thermal power, sunlight heat absorption power and radiation heat dissipation power at the moment k-1 by the lead;
the equivalent convective thermal resistance of the wire at the moment k-1;
is the ambient temperature of the wire at time k-1.
In the formula (5), k is time; similarly, k-1 is the last moment; Δ t is the time interval between two moments;
the operating temperature of the overhead conductor at the moment k;
the operating temperature of the overhead conductor at the moment k-1 is obtained;
and
respectively generating thermal power, sunlight heat absorption power and radiation heat dissipation power by the overhead conductor at the moment k-1;
the equivalent thermal convection resistance of the overhead conductor at the moment of k-1 is obtained;
is the ambient temperature of the overhead conductor at time k-1.
In the formula (6)
The operating temperature of the lead wire infinitesimal i at the moment k is shown;
the operating temperature of the lead wire infinitesimal i at the moment k-1 is shown;
the operating temperature of the lead wire infinitesimal i-1 at the moment k-1 is shown;
the operating temperature of the lead wire infinitesimal i +1 at the moment k-1 is obtained;
and
respectively generating thermal power, sunlight heat absorption power and radiation heat dissipation power by the lead infinitesimal i at the moment of k-1;
the equivalent convective thermal resistance of the wire infinitesimal i at the moment of k-1 is obtained;
is the ambient temperature around the wire micro-element i at time k-1.
And (5) transferring to the step 2.
Step 2: the method comprises the following steps of building an experimental platform for the outdoor axial temperature distribution characteristic of the overhead conductor, acquiring monitoring data of the axial temperature distribution of the experimental conductor and the ambient meteorological environment through the experimental platform for the outdoor axial temperature distribution characteristic of the overhead conductor, simulating the axial temperature distribution of the conductor by combining the monitoring data with a calculation model, and further acquiring the axial temperature distribution characteristic of the conductor under different current levels and outdoor random meteorological conditions, wherein the experimental platform specifically comprises the following steps:
step 2-1), an overhead conductor outdoor axial temperature distribution characteristic test platform is built, monitoring data of experimental conductor axial temperature distribution and surrounding meteorological environment are obtained through the overhead conductor outdoor axial temperature distribution characteristic test platform, and the monitoring data comprise: conductor loading current history sequence IuOperational temperature history sequence of all micro elements of wire
Ambient temperature history sequence around all micro-elements of a wire
And the historical sequence of the solar radiation intensity of all the infinitesimal elements of the wire
Wherein U ∈ [1, U ]; u represents a certain time in the historical sequence, U represents the length of the historical sequence, and n represents the total number of the lead axial infinitesimal divisions.
Step 2-2) calculating an equivalent convective resistance history sequence of the wire infinitesimal, wherein the equivalent convective resistance history sequence comprises the following steps: boundary infinitesimal equivalent convective thermal resistance historical sequence
Equivalent convective thermal resistance history sequence of non-boundary infinitesimal
According to equation (5), the calculation formula of the wire boundary infinitesimal equivalent convective resistance is:
according to equation (6), the calculation formula of the wire non-boundary infinitesimal equivalent convective resistance is:
step 2-3) respectively simulating weather related parameters in the wire boundary micro element and the non-boundary micro element, wherein the weather related parameters comprise: equivalent convective resistance, solar radiation intensity and ambient temperature; obtaining a simulation sequence of the wire boundary micro-element meteorological related parameters at the future m moments by simulation according to a two-dimensional Markov chain method
And
on the basis of obtaining wire boundary micro-element meteorological related parameters, a simulation sequence of future m-moment wire non-boundary micro-element meteorological related parameters is simulated and obtained according to a conditional probability method
And
wherein, M ∈ [1, M]And M represents the length of the analog sequence.
Step 2-4), calculating axial temperature distribution of the wire: simulating sequence of generated wire boundary micro-element weather related parameters
And
carry-in (5) for generating wire boundary infinitesimal operation temperature simulation sequence at m time in future
Base for obtaining wire boundary infinitesimal operation temperature simulation sequenceBased on the generated wire non-boundary infinitesimal simulation sequence
And
carry-in (6) generated future m-time wire non-boundary infinitesimal operation temperature simulation sequence
Finally, obtaining the operating temperature simulation sequence of all the micro-elements in the axial direction of the lead
With reference to fig. 3 to 6, the test platform for the outdoor axial temperature distribution characteristics of the overhead conductor is built outdoors without a barrier. The test platform for the outdoor axial temperature distribution characteristics of the overhead conductor comprises a large current generator 2, a splicing sleeve 3, a support frame 5, a heating device 6, a CT power supply 7, a current transformer 8, a conductor temperature sensor group 9, an environmental temperature sensor group 13, a miniature weather station 10, a wireless data acquisition device 11, an upper computer 12 and a plurality of lifting ropes 4. The heating device 6 is arranged on the overhead conductor 1 to be tested and used for forming a local hot spot on the overhead conductor 1 so as to generate axial temperature distribution on the overhead conductor 1 under outdoor random meteorological conditions, the conductor temperature sensor group 9 comprises a plurality of temperature sensors and is arranged on the overhead conductor 1 and used for measuring the axial temperature distribution of the overhead conductor 1, the environment temperature sensor group 13 comprises 2 temperature sensors, one temperature sensor is arranged in the heating device 6, the other temperature sensor is arranged outside the heating device 6 and is used for respectively measuring the environment temperature in the heating device 6 and the environment temperature outside the heating device 6; 1 end to end of air wire links to each other through splicing sleeve 3 and constitutes an annular current return circuit, air wire 1 is unsettled to be fixed on support frame 5 through a plurality of lifting ropes 4, heavy current generator 2 is used for producing the electric current, be located under air wire 1, with its current coupling who produces to air wire 1 on, CT power 7 and current transformer 8 set up on air wire 1, and link to each other with wireless number collection device 11 respectively, miniature weather station 10 includes wind speed wind direction sensor 17 and solar radiation sensor 18, be fixed in on support frame 5, wind speed wind direction sensor and solar radiation sensor link to each other with wireless number collection device 11 respectively, wireless number collection device 11 transmits monitoring data to host computer PC 12.
Example 1
The overhead conductor 1 is connected end to end through a splicing sleeve 3 with the model number of JYD-240/40. The large current generator 2 is used for generating current, and the maximum loading current of the experiment can reach 1000A. The support frame 5 in the test platform is a steel frame, and plays a good role in supporting. A plurality of lifting ropes 4 in the test platform are made of high-temperature-resistant glass fiber ropes with low heat conductivity and are used for hanging the overhead conductor 1 on a cross beam of the support frame 5. The support frame 5 has a height of 3m, a width of 0.6m and a length of 3 m. The model of the overhead conductor in the test platform is LGJ-240/40 steel-cored aluminum stranded wire, and the total length is 8 meters.
The heating device 6 is a temperature-controllable heating device with a closed space, is arranged on the overhead conductor 1, and a section of the overhead conductor 1 wrapped on the heating device 6 is in natural convection, namely under the windless condition. As shown in fig. 5, the heating wire 19 is installed inside the heating device 6, the heating device 6 provides 24V direct current through the CT power supply 7, the output voltage of the field effect transistor MOSFET20 is controlled through the PWM duty ratio of the single chip microcomputer, and the current in the heating wire 19 is adjusted. The higher the current in the heating wire 19, the higher the temperature in the heating means 6.
The lead temperature sensor group 9 includes 11 temperature sensors, and the position of each temperature sensor in the lead temperature sensor group 9 is as follows: because the overhead conductor 1 has axial temperature distribution under the experimental platform, a plurality of temperature acquisition points need to be arranged so as to comprehensively acquire the axial temperature distribution data of the conductor. As shown in FIG. 6, in the axial temperature distribution characteristic experiment platform, the total length of the temperature acquisition points is set to be 200cm, the distance between the temperature acquisition points is set to be 20cm, and 11 temperature acquisition points are arranged in total. 1 measuring point is arranged on the surface of the wire corresponding to the central position of the temperature heating device 6, and a temperature sensor 26 is arranged to measure the operating temperature of the wire corresponding to the central position in the heating device 6. 2 measuring points are respectively arranged on the surfaces of the wires corresponding to the two sides of the heating device 6, and temperature sensors (25, 27) are arranged to measure the operating temperatures of the wires corresponding to the two sides of the heating device 6. The heating devices 6 are arranged in sequence in the horizontal direction towards the two sides of the wire, 8 measuring points are arranged on the surface of the wire at equal intervals, and temperature sensors (21, 22, 23, 24, 28, 29, 30, 31) are arranged to measure the operating temperature of the wire at the two sides of the temperature heating devices 6.
As shown in fig. 4, the wireless data acquisition device 11 includes 28035 Digital Signal Processor (DSP)14, current transformer 8, GPRS module 15, wind speed and direction sensor 17, wire temperature sensor group 9, ADS1256 module 16, solar radiation sensor 18, and ambient temperature sensor group 13. The wire temperature sensor group 9 can measure the axial temperature distribution data of the experimental wire by using a thermistor. In the operation process, the wireless data acquisition device 11 is powered by the CT power supply 7. The wind speed and direction sensor 17, the current transformer 8, the sunshine radiation sensor 18 and the ambient temperature sensor group 13 are connected with an AD pin of the DSP 14; a part of sensors in the lead temperature sensor group 9 are connected with AD pins of the DSP 14; the rest sensors in the wire temperature sensor group 9 are connected with the AD pin of the ADS1256 module 16; the ADS1256 module 16 is connected with an SPI pin of the DSP 14; the GPRS module 15 is connected with a UART pin of the DSP 14; the CT power supply 7 is connected with the DSP14 and supplies power to the DSP 14; gather wire axis temperature distribution data by wire temperature sensor group 9, gather environment wind speed and wind direction by wind speed direction sensor 17, gather environment solar radiation by solar radiation sensor 18, gather ambient temperature by ambient temperature sensor group 13, gather the electric current of wire by current transformer 8 to with above-mentioned data transmission to DSP14, DSP14 transmits host computer 12 through GPRS module 15.
In summary, the invention performs random simulation by using historical data measured by an overhead conductor axial temperature distribution characteristic test platform based on the division of conductor boundary infinitesimal and non-boundary infinitesimal, and can obtain the conductor axial temperature distribution characteristics under outdoor random meteorological conditions and different current levels.
Claims (8)
1. A random simulation method and a test platform for outdoor axial temperature distribution characteristics of an overhead conductor are characterized by comprising the following steps:
step 1: constructing an outdoor axial temperature distribution calculation model of the overhead conductor;
step 2: the method comprises the steps of building an overhead conductor outdoor axial temperature distribution characteristic test platform, obtaining monitoring data of experimental conductor axial temperature distribution and surrounding meteorological environment through the overhead conductor outdoor axial temperature distribution characteristic test platform, simulating conductor axial temperature distribution by utilizing the monitoring data in combination with a temperature calculation model, and further obtaining conductor axial temperature distribution characteristics under different current levels and outdoor random meteorological conditions.
2. The method for randomly simulating the outdoor axial temperature distribution characteristics of the overhead conductors according to claim 1, wherein the step 1 of constructing the outdoor axial temperature distribution calculation model of the overhead conductors specifically comprises the following steps:
1-1) equally dividing the overhead conductor along the radial direction to obtain axial infinitesimal conductors with the same length;
step 1-2) dividing the obtained axial micro-elements of the wire into boundary micro-elements and non-boundary micro-elements; the heat balance equation of the wire of the boundary infinitesimal is as follows:
t in formula (1) is time; t iscThe operating temperature of the wire; c is the equivalent heat capacity of the lead; q. q.sJ、qs、qcAnd q isrRespectively generating thermal power, sunlight heat absorption power, convection heat dissipation power and radiation heat dissipation power for the current of the lead;
the wire thermal equilibrium equation for the non-boundary infinitesimal is:
in the formula (2), i represents the ith infinitesimal, and similarly, i-1 represents the i-1 st infinitesimal; t isc,iThe operating temperature of the wire infinitesimal i; ciThe equivalent heat capacity of the lead wire micro element i; q. q.sJ,i、qs,i、qc,iAnd q isr,iRespectively generating thermal power, sunlight heat absorption power, convection heat dissipation power and radiation heat dissipation power for the wire infinitesimal i current; q. q.sd,i-1The thermal power is conducted from the lead micro element i-1 to the micro element i; q. q.sd,iThe thermal power conducted from the lead infinitesimal i to the infinitesimal i + 1;
step 1-3) performing hot circuit model equivalence on the formula (1) and the formula (2) comprises the following steps:
r in the formula (3)cIs the equivalent convective thermal resistance of the overhead conductor; t iseAmbient temperature around the overhead conductor;
t in formula (4)c,i-1The operating temperature is the wire infinitesimal i-1 operating temperature; t isc,i+1The operating temperature is the wire infinitesimal i + 1; rdmIs the conduction thermal resistance of the wire infinitesimal i; cmThe equivalent heat capacity of the lead wire micro element i; rc,iIs equivalent convective thermal resistance of the wire infinitesimal i; t ise,iIs the ambient temperature around the wire infinitesimal i;
step 1-4), when the parameters of the overhead conductor and the external environment parameters are known, combining the initial temperature of the overhead conductor, calculating the axial temperature distribution of the conductor at any time by utilizing an outdoor axial temperature distribution calculation model of the overhead conductor, wherein the conductor temperature of a boundary infinitesimal and a non-boundary infinitesimal of the conductor at a time k is represented as follows:
in the formula (5), k is time; similarly, k-1 is the last moment; Δ t is the time interval between two moments;
the operating temperature of the overhead conductor at the moment k;
the operating temperature of the overhead conductor at the moment k-1 is obtained;
and
respectively generating thermal power, sunlight heat absorption power and radiation heat dissipation power by the overhead conductor at the moment k-1;
the equivalent thermal convection resistance of the overhead conductor at the moment of k-1 is obtained;
the ambient temperature of the overhead conductor at the time k-1;
in the formula (6)
The operating temperature of the lead wire infinitesimal i at the moment k is shown;
the operating temperature of the lead wire infinitesimal i at the moment k-1 is shown;
the operating temperature of the lead wire infinitesimal i-1 at the moment k-1 is shown;
for the wire infinitesimal i +1 at the time k-1The operating temperature of (d);
and
respectively generating thermal power, sunlight heat absorption power and radiation heat dissipation power by the lead infinitesimal i at the moment of k-1;
the equivalent convective thermal resistance of the wire infinitesimal i at the moment of k-1 is obtained;
the ambient temperature of the wire micro element i at the moment k-1 is shown;
and (5) transferring to the step 2.
3. The method and the test platform for random simulation of the outdoor axial temperature distribution characteristics of the overhead conductors according to claim 2, wherein an outdoor axial temperature distribution characteristic test platform of the overhead conductors is set up in the step 2, monitoring data of the axial temperature distribution of the test conductors and the ambient meteorological environment are obtained through the outdoor axial temperature distribution characteristic test platform of the overhead conductors, the axial temperature distribution of the conductors is simulated by combining the monitoring data with a calculation model, and then the axial temperature distribution characteristics of the conductors under different current levels and outdoor random meteorological conditions are obtained, and the method and the test platform specifically comprise the following steps:
step 2-1), an overhead conductor outdoor axial temperature distribution characteristic test platform is built, monitoring data of experimental conductor axial temperature distribution and surrounding meteorological environment are obtained through the overhead conductor outdoor axial temperature distribution characteristic test platform, and the monitoring data comprise: conductor loading current history sequence IuOperational temperature history sequence of all micro elements of wire
Ambient temperature history sequence around all micro-elements of a wire
And the historical sequence of the solar radiation intensity of all the infinitesimal elements of the wire
Wherein U ∈ [1, U ]; u represents a certain moment in the historical sequence, the U represents the length of the historical sequence, and n represents the total number of the axial infinitesimal division of the lead;
step 2-2) calculating an equivalent convective resistance history sequence of the wire infinitesimal, wherein the equivalent convective resistance history sequence comprises the following steps: boundary infinitesimal equivalent convective thermal resistance historical sequence
Equivalent convective thermal resistance history sequence of non-boundary infinitesimal
According to equation (5), the calculation formula of the wire boundary infinitesimal equivalent convective resistance is:
according to equation (6), the calculation formula of the non-boundary infinitesimal equivalent convective resistance of the wire is:
step 2-3) respectively simulating weather related parameters in the wire boundary micro element and the non-boundary micro element, wherein the weather related parameters comprise: equivalent convective resistance, solar radiation intensity and ambient temperature; obtaining a simulation sequence of the wire boundary micro-element meteorological related parameters at the future m moments by simulation according to a two-dimensional Markov chain method
And
on the basis of obtaining wire boundary micro-element meteorological related parameters, a simulation sequence of future m-moment wire non-boundary micro-element meteorological related parameters is simulated and obtained according to a conditional probability method
And
wherein M belongs to [1, M ], and M represents the length of the simulation sequence;
step 2-4), calculating axial temperature distribution of the wire: simulating sequence of generated wire boundary micro-element weather related parameters
And
carry-in (5) for generating wire boundary infinitesimal operation temperature simulation sequence at m time in future
On the basis of obtaining the wire boundary infinitesimal operation temperature simulation sequence, the generated wire non-boundary infinitesimal simulation sequence is used
And
carry-in (6) generated future m-time wire non-boundary infinitesimal operation temperature simulation sequence
Finally, obtaining the running temperature model of all the micro-elements in the axial direction of the leadPseudo sequence
4. The utility model provides an outdoor axial temperature distribution characteristic test platform of overhead conductor which characterized in that: the system comprises a large current generator (2), a splicing sleeve (3), a support frame (5), a heating device (6), a CT power supply (7), a current transformer (8), a wire temperature sensor group (9), an environmental temperature sensor group (13), a micro meteorological station (10), a wireless data acquisition device (11), an upper computer (12) and a plurality of lifting ropes (4); the heating device (6) is arranged on an overhead conductor (1) to be tested and used for forming a local hot spot on the overhead conductor (1) so as to generate axial temperature distribution on the overhead conductor (1) under outdoor random meteorological conditions, the conductor temperature sensor group (9) comprises a plurality of temperature sensors and is arranged on the overhead conductor (1) and used for measuring the axial temperature distribution of the overhead conductor (1), the environment temperature sensor group (13) comprises 2 temperature sensors, one temperature sensor is arranged in the heating device (6), the other temperature sensor is arranged outside the heating device (6) and is used for respectively measuring the environment temperature in the heating device (6) and the environment temperature outside the heating device (6); overhead conductor (1) end to end passes through splicing sleeve (3) and links to each other and constitutes an annular current return circuit, overhead conductor (1) is unsettled to be fixed on support frame (5) through a plurality of lifting ropes (4), heavy current generator (2) are used for producing the electric current, be located under overhead conductor (1), with the current coupling of its production to overhead conductor (1) on, CT power (7) and current transformer (8) set up on overhead conductor (1), and link to each other with wireless number acquisition device (11) respectively, miniature meteorological station (10) include wind speed wind direction sensor (17) and sunshine radiation sensor (18), be fixed in on support frame (5), wind speed wind direction sensor and sunshine radiation sensor link to each other with wireless number acquisition device (11) respectively, wireless number acquisition device (11) transmit monitoring data to host computer PC (12).
5. The overhead conductor outdoor axial temperature distribution characteristic test platform of claim 4, wherein: each temperature sensor in the conductor temperature sensor group (9) is arranged as follows, 1 temperature sensor is arranged on the surface of the overhead conductor (1) corresponding to the central position of the heating device (6), the temperature sensors are sequentially arranged in the horizontal direction towards the two sides of the overhead conductor (1) according to the position, and other temperature sensors are arranged on the surface of the overhead conductor (1) at equal intervals.
6. The overhead conductor outdoor axial temperature distribution characteristic test platform of claim 4, wherein: the heating device (6) is a temperature-controllable heating device with a closed space, is arranged on the overhead conductor (1), and a section of the overhead conductor (1) wrapped on the heating device (6) is in natural convection, namely under the windless condition.
7. The outdoor axial temperature distribution characteristic experiment platform for overhead conductors of claim 4 or 6, wherein: the heating device (6) is heated by adopting an electric heating wire, and the current in the electric heating wire (19) is adjusted through a field effect transistor MOSFET (20).
8. The outdoor axial temperature distribution characteristic experiment platform for overhead conductors of claim 4, wherein: the wireless data acquisition device (11) comprises a DSP (14), a GPRS module (15), an ADS1256 module (16), a wind speed and direction sensor (17), a sunshine radiation sensor (18) and an ambient temperature sensor group (13); the wind speed and direction sensor (17), the current transformer (8), the sunshine radiation sensor (18) and the environment temperature sensor group (13) are respectively connected with an AD pin of the DSP (14); a part of sensors in the wire temperature sensor group (9) are connected with AD pins of the DSP (14); the rest sensors in the wire temperature sensor group (9) are connected with the AD pin of the ADS1256 module (16); the ADS1256 module (16) is connected with an SPI pin of the DSP (14) and is used for increasing the number of temperature sensors; the GPRS module (15) is connected with a UART pin of the DSP (14); the CT power supply (7) is connected with the DSP (14) and supplies power to the DSP (14); gather overhead transmission line wire axial temperature distribution by wire temperature sensor group (9), gather environment wind speed and wind direction by wind speed wind direction sensor (17), gather environment solar radiation intensity by solar radiation sensor (18), gather ambient temperature by ambient temperature sensor group (13), gather the wire current by current transformer (8), and with above-mentioned data transmission to DSP (14), DSP (14) transmit host computer PC (12) through GPRS module (15).
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| CN114923515A (en) * | 2022-04-21 | 2022-08-19 | 广东电网有限责任公司 | Temperature early warning method, device, system and medium for power transmission conductor |
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