CN111239473A - Broken string connects pole tower trouble step voltage risk evaluation system under perpendicular layering soil - Google Patents
Broken string connects pole tower trouble step voltage risk evaluation system under perpendicular layering soil Download PDFInfo
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- G01R19/16576—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing DC or AC voltage with one threshold
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Abstract
The invention relates to a fault step voltage risk assessment system for a broken line extension rod tower under vertical layered soil, which comprises a Rogowski coil current sensor, an emergency alarm lamp, a sound alarm system, a projector and a system control circuit, wherein the Rogowski coil current sensor is connected with the emergency alarm lamp; the system control circuit comprises a direct current power supply module, a signal processing module, an operational amplification module and a wireless transmission module; the direct current power supply module, the signal processing module and the operational amplification module are sequentially connected; the direct current power supply module comprises a solar panel, a lithium ion battery and a charge and discharge control circuit; the solar panel and the charge-discharge control circuit are respectively connected with the lithium ion battery; the signal processing module is also connected with the Rogowski coil current sensor, the emergency alarm lamp, the projector and the wireless transmitting module; the output end of the operational amplification module is connected with a sound alarm system. The invention divides the step voltage dangerous area by calculating the bearable current of the human body, gives an audible alarm when a fault exists, and projects according to the danger level.
Description
Technical Field
The invention belongs to the technical field of electric power system grounding analysis, and particularly relates to a step voltage risk assessment system for a fault of a broken line extension rod tower under vertical layered soil.
Background
Electric energy plays an important role in human social life, the electric demand and the economy are closely related, and a power distribution network is an important component in a power system, the accidents of the power distribution network account for about 90% of the total accidents of the power system, and the single-phase grounding short-circuit fault is the most common fault form in the power distribution network. After a single-phase ground short-circuit fault occurs, a large short-circuit current may be caused around a short-circuit point, and the short-circuit current may cause a large step voltage on the nearby ground due to the current dispersion of the surrounding soil, so that the life safety of residents is threatened.
The problem of the single-phase broken line extension tower fault of the distribution network is always solved. At present, many researches aiming at single-phase earth faults at home and abroad mainly focus on a human body resistance model, a neutral point grounding mode and the like, and researches on step voltage and contact voltage distribution calculation and a personal safety evaluation method under different soil structures (such as vertical layered soil) are lacked. In order to guarantee the life safety of workers and local residents, an intelligent risk assessment method is urgently needed to divide the danger level in a fault area and send out a safety alarm in time.
Disclosure of Invention
The invention aims to solve the defects of the prior art and provides a fault step voltage risk assessment system for a broken line extension rod tower under vertical layered soil.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the system for evaluating the step voltage risk of the fault of the broken line extension rod tower under the vertical layered soil comprises a Rogowski coil current sensor, an emergency alarm lamp, a sound alarm system, a projector and a system control circuit;
the system control circuit comprises a direct current power supply module, a signal processing module, an operational amplification module and a wireless transmission module;
the direct current power supply module, the signal processing module and the operational amplification module are sequentially connected;
the direct-current power supply module comprises a solar panel, a lithium ion battery and a charge and discharge control circuit;
the solar panel and the charge-discharge control circuit are respectively connected with the lithium ion battery;
the signal processing module is also connected with the Rogowski coil current sensor, the emergency alarm lamp, the projector and the wireless transmitting module;
the output end of the operational amplification module is connected with a sound alarm system.
Further, it is preferable that a housing is further included; the solar panel is arranged on the right side of the shell; the projector is arranged right below the shell and connected with the bottom of the shell; the emergency alarm lamp and the wireless sending module are arranged on the outer top of the shell; the sound alarm system is installed at a lower portion of the front surface of the housing.
Further, it is preferable that the projector is connected to the bottom of the housing by a fixing rod; the upper end of the fixed rod is fixedly connected with the bottom of the shell through a third screw and a fourth screw; the lower end of the fixing rod is fixedly connected with the projector through a first screw and a second screw.
Further, preferably, the shell further comprises a first angle steel type fastener and a second angle steel type fastener, and the first angle steel type fastener and the second angle steel type fastener are both arranged on the left side of the shell.
In a safe area, people basically cannot feel current; in the four dangerous areas, although the disease is difficult to bear, the disease has little influence on muscles; in the three dangerous areas, the human body feels very pain and muscle contraction occurs and causes breathing difficulty; in the second-risk area, the human body can generate respiratory depression and permanent damage; in an area of constant risk, the body experiences ventricular fibrillation, cardiac arrest, and may be fatal.
Further, preferably, the projector displays five areas by adopting different colors according to the third step, so that the calculation of the earth surface potential of the surrounding area and the graded alarm when the line is disconnected and connected with the tower are realized.
The invention also provides a method for evaluating the step voltage risk of the fault of the lower broken line connecting rod tower in the vertical layered soil, which adopts the step voltage risk evaluating system for the fault of the lower broken line connecting rod tower in the vertical layered soil, and is characterized by comprising the following steps of:
step one, calculating any point P of earth electrode soil area in faultmPotential value V ofPm：
Setting the total circumference of a cross grounding device of a tower fixed by the evaluation system to be L, dividing the cross grounding device into n sections of conductors with the same size, and setting the leakage current of the j section of conductor to be IjHaving a length LjThen at any point P on the earth's surface around the towermThe generated potential VPmComprises the following steps:
in the formula, RTjThe contact resistance of the j section conductor; rPmjA mutual resistance equal to P when a unit current is applied to the j-th conductormThe potential of the dot; g is the number of calculation points; c is a correction coefficient;
RTj＝12.2182h0 0.76·ρ0 0.85·In(ρ1) (2)
in the formula, ρ1The resistivity of the left soil near the tower; because the grounding device is not completely contacted with the soil closely, a contact layer formed by soil particles and air gaps exists, rho0Is a contact layerElectrical resistivity; h is0Is the contact layer thickness;
the mutual resistance of the left soil area under the rectangular coordinate system is as follows:
the right soil area mutual resistance is:
in the formulas (3) and (4), the geometric center of the cross-shaped grounding device is taken as the origin of coordinates, the Z axis is vertical to the ground and faces downwards, the X axis is parallel to the power transmission line and points to the user side, and the Y axis rotates 90 degrees anticlockwise when the user looks from the sky to the earth surface; the method comprises the following steps of vertically dividing soil along an X axis, wherein the left side soil is arranged on one side of the X axis in the negative direction, the right side soil is arranged in the positive direction, and H is the distance from the geometric center of the grounding device to an interface; (x)j,yj,zj) The coordinates of the center point of the j section conductor; (x)m,ym,zm) For any point P on the groundmThe coordinates of (a); (x)mj’,ymj’,zmj’,zmj1’)＝(xm-xj, ym-yj,zm-zj,zm+zj)；ρ2Resistivity of the soil on the right side; hjThe distance from the center point of the j section of conductor to the interface is obtained;
second, the current value I flowing through the human body is measured by a potentiometer having two points P, Q at an arbitrary distance of 1m from the earth's surfaceP：
In the formula (6), VP、VQP, Q are potential values of two points respectively; rinIs a human body internal resistor; r0Is a personBody skin resistance; b is the equivalent grounding radius of the human body; ρ is the average resistivity of P, Q two points;
in the formula (7), (x)1,y1,z1)、(x2,y2,z2) P, Q two-point coordinates respectively taking the geometric center of the cross grounding device as the origin of coordinates; d is the maximum value of the distance from the two points P, Q to the center of the cross-shaped grounding device;
thirdly, dividing a step voltage danger area according to the bearable current of the human body:
when I isPWhen the current value is 100mA, D is calculated corresponding to P, Q two points1(ii) a All the same asPWhen D is 25mA, D is D2； IPWhen D is 6mA, D is D3；IPWhen 1mA, D is D4；
When I isP>100mA, i.e. D<D1The area is at first-class danger; when 25 is turned on<IP<100mA, i.e. D1<D<D2The area is at the same risk level; when 6 is<IP<25mA, i.e. D2<D<D3The area is three risks; when 1 is<IP<6mA, i.e. D3<D<D4Then, the area is at risk of four; when I isP<1mA, i.e. D>D4When, this area is a safe area.
Further, it is preferable that the value of c is calculated by the following algorithm:
①, initializing, namely setting an evolution algebra counter u to be 0, setting a maximum evolution algebra G to be 100, and randomly generating 50 different c values as an initial population P (0);
② evaluation of individuals by calculating the fitness f (c) of each individual in the population according to the formula;
wherein, V'PmIs a point PmCalculating the potential of the real sample;
③ genetic operation, which comprises selecting, crossing and mutating according to the fitness of each individual in the population to generate new generation of individuals;
④, if u is less than or equal to G, u is equal to u +1, go to step ②, if u is greater than G, then the individual c with the maximum fitness obtained in the evolution process is used as the optimal solution output, and the calculation is terminated.
Further, it is preferable that the projector (106) displays five regions by projection with different colors according to the third step.
Compared with the prior art, the invention has the beneficial effects that:
1) the earth surface potential of the area around the vertically layered soil can be calculated;
2) the influence of a human equivalent circuit and contact resistance is fully considered when the current passing through the human body is calculated;
3) dividing a step voltage dangerous area by calculating the bearable current of a human body;
4) the system can give an alarm by sound when faults exist and project according to the danger level.
Drawings
FIG. 1 is a schematic view of the present invention in use;
FIG. 2 is a schematic structural diagram of a fault step voltage risk assessment system for a broken line extension rod tower under vertical layered soil according to the present invention;
FIG. 3 is a schematic diagram of the system control circuit of the present invention;
1, a first tower; 2. a second tower; 3. a third tower; 4. a first power transmission line; 5. a second power transmission line; 6. Breaking a first wire; 7. a second wire is broken; 8. a third power transmission line; 9. a fourth power transmission line; 10. a fifth power transmission line; 11. a first cross grounding device; 12. a second cross grounding device; 13. a cross grounding device III; 14. right soil; 15. a risk assessment system; 16. left side soil; 100. a housing; 101. a rogowski coil current sensor; 102. a first angle steel type fastener; 103. a second angle steel type fastener; 104. an emergency warning light; 105. a sound alarm system; 106. a projector; 107. a solar panel; 108. a wireless transmission module; 109. fixing the rod; 110. a first screw; 111. a second screw; 112. a third screw; 113. a fourth screw; 200. a system control circuit; 201. A DC power supply module; 202. a signal processing module; 203. a lithium ion battery; 204. a charge and discharge control circuit; 205. and an operational amplification module.
Detailed Description
The present invention will be described in further detail with reference to examples.
It will be appreciated by those skilled in the art that the following examples are illustrative of the invention only and should not be taken as limiting the scope of the invention. The examples do not specify particular techniques or conditions, and are performed according to the techniques or conditions described in the literature in the art or according to the product specifications. The materials or equipment used are not indicated by manufacturers, and all are conventional products available by purchase.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.
In the description of the present invention, "a plurality" means two or more unless otherwise specified. The terms "inner," "upper," "lower," and the like, refer to an orientation or a state relationship based on that shown in the drawings, which is for convenience in describing and simplifying the description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "provided" are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. To those of ordinary skill in the art, the specific meanings of the above terms in the present invention are understood according to specific situations.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
As shown in fig. 2 and 3, the system for evaluating the step voltage risk of the fault of the pole tower of the broken line under the vertical layered soil comprises a rogowski coil current sensor 101, an emergency alarm lamp 104, an acoustic alarm system 105, a projector 106 and a system control circuit 200;
the system control circuit 200 comprises a direct current power supply module 201, a signal processing module 202, an operational amplification module 205 and a wireless transmission module 108;
the direct current power supply module 201, the signal processing module 202 and the operational amplification module 205 are connected in sequence;
the direct current power supply module 201 comprises a solar panel 107, a lithium ion battery 203 and a charge and discharge control circuit 204;
the solar panel 107 and the charge and discharge control circuit 204 are respectively connected with the lithium ion battery 203;
the signal processing module 202 is also connected with the rogowski coil current sensor 101, the emergency warning lamp 104, the projector 106 and the wireless transmitting module 108;
the output end of the operational amplification module 205 is connected with the sound alarm system 105.
Preferably, further comprises a housing 100; solar panel 107 is mounted on the right side of housing 100; the projector 106 is installed right below the casing 100 and connected to the bottom of the casing 100; the emergency warning lamp 104 and the wireless transmission module 108 are arranged at the outer top of the shell 100; the acoustic alarm system 105 is installed at a lower portion of the front surface of the housing 100.
Preferably, the projector 106 is connected to the bottom of the housing 100 by a fixing rod 109; the upper end of the fixing rod 109 is fixedly connected with the bottom of the shell 100 through a third screw 112 and a fourth screw 113; the lower end of the fixing rod 109 is fixedly connected with the projector 106 through a first screw 110 and a second screw 111.
Preferably, the portable terminal further comprises a first angle steel type fastener 102 and a second angle steel type fastener 103, and the first angle steel type fastener 102 and the second angle steel type fastener 103 are both arranged on the left side of the shell 100.
A method for evaluating the step voltage risk of a fault of a broken line connecting rod tower under vertical layered soil adopts the step voltage risk evaluation system of the fault of the broken line connecting rod tower under vertical layered soil, and comprises the following steps:
step one, calculating any point P of earth electrode soil area in faultmPotential value V ofPm：
Setting the total circumference of a cross grounding device of a tower fixed by the evaluation system to be L, dividing the cross grounding device into n sections of conductors with the same size, and setting the leakage current of the j section of conductor to be IjHaving a length LjThen at any point P on the earth's surface around the towermThe generated potential VPmComprises the following steps:
in the formula, RTjThe contact resistance of the j section conductor; rPmjA mutual resistance equal to P when a unit current is applied to the j-th conductormThe potential of the dot; g is the number of calculation points; c is a correction coefficient;
RTj＝12.2182h0 0.76·ρ0 0.85·In(ρ1) (2)
in the formula, ρ1The resistivity of the soil on the left side (lower left in the figure) near the tower; because the grounding device is not completely contacted with the soil closely, a contact layer formed by soil particles and air gaps exists, rho0Is the contact layer resistivity; h is0Is the contact layer thickness;
the mutual resistance of the left soil area under the rectangular coordinate system is as follows:
the right soil area mutual resistance is:
in the formulas (3) and (4), the geometric center of the cross-shaped grounding device is taken as the origin of coordinates, the Z axis is vertical to the ground and faces downwards, the X axis is parallel to the power transmission line and points to the user side, and the Y axis rotates 90 degrees anticlockwise when the user looks from the sky to the earth surface; the method comprises the following steps of vertically dividing soil along an X axis, wherein the left side soil is arranged on one side of the X axis in the negative direction, the right side soil is arranged in the positive direction, and H is the distance from the geometric center of the grounding device to an interface; (x)j,yj,zj) The coordinates of the center point of the j section conductor; (x)m,ym,zm) For any point P on the groundmThe coordinates of (a); (x)mj’,ymj’,zmj’,zmj1’)＝(xm-xj, ym-yj,zm-zj,zm+zj)；ρ2Resistivity of the soil on the right side; hjThe distance from the center point of the j section of conductor to the interface is obtained;
the value of c is calculated by the following algorithm:
①, initializing, namely setting an evolution algebra counter u to be 0, setting a maximum evolution algebra G to be 100, and randomly generating 50 different c values as an initial population P (0);
② evaluation of individuals by calculating the fitness f (c) of each individual in the population according to the formula;
wherein, V'PmIs a point PmCalculating the potential of the real sample;
③ genetic operation, namely generating new generation individuals by adopting MATLAB default selection, crossing and mutation operations according to the fitness of each individual in a population;
④, if u is less than or equal to G, u is equal to u +1, go to step ②, if u is greater than G, the individual c with the maximum fitness obtained in the evolution process is used as the optimal solution output, and the calculation is stopped;
second, the current value I flowing through the human body is measured by a potentiometer having two points P, Q at an arbitrary distance of 1m from the earth's surfaceP：
In the formula (6), VP、VQP, Q are potential values of two points respectively; rinIs a human body internal resistor; r0Is the human skin resistance; b is the equivalent grounding radius of the human body; ρ is the average resistivity of P, Q two points;
in the formula (7), (x)1,y1,z1)、(x2,y2,z2) P, Q two-point coordinates respectively taking the geometric center of the cross grounding device as the origin of coordinates; d is the maximum value of the distance from the two points P, Q to the center of the cross-shaped grounding device;
thirdly, dividing a step voltage danger area according to the bearable current of the human body:
when I isPWhen the current value is 100mA, D is calculated corresponding to P, Q two points1(ii) a All the same asPWhen D is 25mA, D is D2； IPWhen D is 6mA, D is D3；IPWhen 1mA, D is D4；
When I isP>100mA is D<D1The area is at first-class danger; when 25 is turned on<IP<100mA is D1<D<D2The area is at the same risk level; when 6 is<IP<25mA i.e. D2<D<D3The area is three risks; when 1 is<IP<6mA is D3<D<D4Then, the area is at risk of four; when I isP<1mA is D>D4When, this area is a safe area.
And the projector displays five areas by adopting different colors according to the third step, thereby realizing calculation of the earth surface potential of the surrounding area when the line is disconnected and the tower is connected and graded alarm.
Examples of the applications
As shown in fig. 1, tower feet of a first tower 1, a second tower 2 and a third tower 3 are grounded through a first cross grounding device 11, a second cross grounding device 12 and a third cross grounding device 13 respectively, and a first transmission line 4, a second transmission line 5, a third transmission line 8, a fourth transmission line 9 and a fifth transmission line 10 are arranged between the first tower 1, the second tower 2 and the third tower 3 to be connected in pairs;
a fifth transmission line 10 is a normal phase A of the transmission line, a first broken line 6 and a second broken line 7 are phases A under the working condition of the transmission line, the second broken line 7 is in short circuit with a second tower 2, short-circuit current flows into the ground through the second tower 2 and a second cross grounding device 12, the first broken line 6 is in a suspended state, a first transmission line 4 and a third transmission line 8 are normal phases B of the transmission line, and a second transmission line 5 and a fourth transmission line 9 are normal phases C of the transmission line;
as shown in fig. 2, risk assessment system 15 includes a housing 100, a rogowski coil current sensor 101, an emergency warning light 104, an audible alarm system 105, a projector 106, and a system control circuit 200;
the system control circuit 200 comprises a direct current power supply module 201, a signal processing module 202, an operational amplification module 205 and a wireless transmission module 108;
the direct current power supply module 201, the signal processing module 202 and the operational amplification module 205 are connected in sequence;
the direct current power supply module 201 comprises a solar panel 107, a lithium ion battery 203 and a charge and discharge control circuit 204, which jointly supply power to the risk assessment system 15;
the solar panel 107 and the charge and discharge control circuit 204 are respectively connected with the lithium ion battery 203;
the signal processing module 202 is also connected with the rogowski coil current sensor 101, the emergency warning lamp 104, the projector 106 and the wireless transmitting module 108;
the output end of the operational amplification module 205 is connected with the sound alarm system 105.
The projector 106 is connected to the bottom of the housing 100 by a fixing rod 109; the upper end of the fixing rod 109 is fixedly connected with the bottom of the shell 100 through a third screw 112 and a fourth screw 113; the lower end of the fixing rod 109 is fixedly connected with the projector 106 through a first screw 110 and a second screw 111. I.e. the projector 106 is suspended directly below the housing 100;
the tower is characterized by further comprising a first angle steel type fastener 102 and a second angle steel type fastener 103, wherein the first angle steel type fastener 102 and the second angle steel type fastener 103 are both arranged on the left side of the shell 100 and are fixed on the second tower 2.
The Rogowski coil current sensor 101 is bound at a tower foot of the second tower 2 and transmits an incoming ground current signal to the signal processing module 202; the signal processing module 202 processes the current signal from the rogowski coil current sensor 101, and outputs a signal to perform light alarm through the emergency alarm lamp 104; performing acoustic alarm with the acoustic alarm system 105 through the operational amplification module 205; projecting a plurality of annular areas on the ground by a projector 106 to represent dangerous areas with different grades; uploading the fault data file through the wireless transmission module 108;
the signal processing module 202 is configured to perform calculation by using the fault step voltage risk assessment method for the vertical stratification soil lower broken line extension rod tower according to claim 1 according to the data acquired by the rogowski coil current sensor 101; then, according to the calculation result, projecting each area on the ground through the projector 106 for warning;
the operational amplification module 205 is configured to amplify the signal transmitted from the signal processing module 202, and then perform an audio alarm through the audio alarm system 105;
calculating any point P of earth electrode soil region in faultmPotential value V ofPm：
When the overhead line is short-circuited to the second tower 2, the fault current of the overhead line can be scattered to vertically layered right side soil 14 and left side soil 16 along the second tower 2 and the second cross grounding device 12, the total circumference of the second cross grounding device 12 is L, the grounding device is divided into n sections of conductors with the same size, and the leakage current of the j section of conductor is set as IjHaving a length LjThen at any point P on the ground surface around the second tower 2mThe generated potential VPmComprises the following steps:
in the formula, RTjThe contact resistance of the j section conductor is in omega; rPmjThe mutual resistance is equal to the potential of a point P when a unit current is applied to the j section conductor, and the unit is omega; g is the number of calculation points; c is a correction coefficient;
RTj＝12.2182h0 0.76·ρ0 0.85·In(ρ1) (9)
in the formula, ρ1The resistivity of the left soil 16 near the second tower 2 is shown as omega · m; because the grounding device is not completely contacted with the soil closely, a contact layer formed by soil particles and air gaps exists, rho0Contact layer resistivity in Ω · m; h is0Is the contact layer thickness in m;
if the left side of the soil is a current source, the mutual resistance of the soil on the left side under the rectangular coordinate system is as follows:
the right soil area mutual resistance is:
in the formulas (10) and (11), the geometric center of the cross-shaped grounding device is taken as the origin of coordinates, the Z axis is vertical to the ground and faces downwards, the X axis is parallel to the power transmission line and points to the user side, and the Y axis rotates 90 degrees anticlockwise when the user looks from the sky to the earth surface; the method comprises the following steps of vertically dividing soil along an X axis, wherein the left side soil is arranged on one side of the X axis in the negative direction, the right side soil is arranged in the positive direction, and H is the distance from the geometric center of the grounding device to an interface; (x)j,yj,zj) The coordinates of the center point of the j section conductor; (x)m,ym,zm) For any point P on the groundmThe coordinates of (a); (x)mj’,ymj’,zmj’,zmj1’)＝(xm- xj,ym-yj,zm-zj,zm+zj)；ρ2Resistivity of the right soil 14 in Ω · m; hjThe distance from the center point of the j section of conductor to the interface is m;
the value of c is calculated by the following algorithm:
①, initializing, namely setting an evolution algebra counter u to be 0, setting a maximum evolution algebra G to be 100, and randomly generating 50 different c values as an initial population P (0);
② evaluation of individuals by calculating the fitness f (c) of each individual in the population according to the formula;
wherein, V'PmIs a point PmCalculating the potential of the real sample;
③ genetic operation, namely generating new generation individuals by adopting MATLAB default selection, crossing and mutation operations according to the fitness of each individual in a population;
④, if u is less than or equal to G, u is equal to u +1, go to step ②, if u is greater than G, the individual c with the maximum fitness obtained in the evolution process is used as the optimal solution output, and the calculation is stopped;
the current value I flowing through the human body is obtained by a potential difference meter of two points P, Q arbitrarily spaced by 1m from the earth surfaceP：
In the formula (13), VP、VQP, Q, the unit is V; rinIs an internal resistance of the human body, and has a value of about 500 omega; r0Is the skin resistance of a human body, and has the unit of omega; b is 0.08(m) which is the equivalent grounding radius of the human body; ρ is the average resistivity of P, Q points in Ω · m; in the formula (14), (x)1,y1,z1)、(x2,y2,z2) P, Q two-point coordinates taking the geometric center of the second cross grounding device 12 as the origin of coordinates respectively; d is the maximum value of the distance from the P, Q two points to the center of the second cross grounding device 12, and the unit is m;
dividing a step voltage dangerous area according to the bearable current of a human body:
when I isPWhen the current value is 100mA, D is calculated corresponding to P, Q two points1(ii) a All the same asPWhen D is 25mA, D is D2； IPWhen D is 6mA, D is D3；IPWhen 1mA, D is D4；
When I isP>100mA, i.e. D<D1The area is at first-class danger; when 25 is turned on<IP<100mA, i.e. D1<D<D2The area is at the same risk level; when 6 is<IP<25mA, i.e. D2<D<D3The area is three risks; when 1 is<IP<6mA, i.e. D3<D<D4Then, the area is at risk of four; when I isP<1mA, i.e. D>D4When, this area is a safe area.
Setting L as 0.8m, n as 8, Ij＝80A，ρ0＝500Ω·m，ρ1＝100Ω·m，ρ2＝500Ω·m，h0Setting the geometric center of the cross grounding device II as (0,0,0.5) and setting the geometric center of the cross grounding device II as (0.0015 m) and g as (30), and setting the geometric center of the cross grounding device II as verticalThe layered interface is x-10, and V of 30 points is calculatedPmAnd the value of the parameter c obtained by calculation by using an algorithm is 0.7709, coordinates of P, Q two points are selected as (3,0,0) and (4,0,0), and R is obtained by calculationTj＝79.105517276115150 Ω，VP＝386.403009026654V，VQAssuming R308.692369534800Vin＝500Ω、R0＝250 Ω、b＝0.08m，IP59.208106279507824mA, D4 m. From 25<IP<100mA, and the area is a double-danger area.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (7)
1. The system for evaluating the fault step voltage risk of the broken line extension tower under the vertical layered soil is characterized by comprising a Rogowski coil current sensor (101), an emergency alarm lamp (104), a sound alarm system (105), a projector (106) and a system control circuit (200);
the system control circuit (200) comprises a direct current power supply module (201), a signal processing module (202), an operational amplification module (205) and a wireless transmission module (108);
the direct current power supply module (201), the signal processing module (202) and the operational amplification module (205) are sequentially connected;
the direct-current power supply module (201) comprises a solar panel (107), a lithium ion battery (203) and a charging and discharging control circuit (204);
the solar panel (107) and the charge and discharge control circuit (204) are respectively connected with the lithium ion battery (203);
the signal processing module (202) is also connected with the Rogowski coil current sensor (101), the emergency alarm lamp (104), the projector (106) and the wireless transmitting module (108);
the output end of the operational amplification module (205) is connected with the sound alarm system (105).
2. The vertical stratified soil sub-line break-and-stick tower fault step voltage risk assessment system according to claim 1, further comprising a housing (100); the solar panel (107) is arranged on the right side of the shell (100); the projector (106) is arranged right below the shell (100) and is connected with the bottom of the shell (100); the emergency alarm lamp (104) and the wireless transmitting module (108) are arranged on the outer top of the shell (100); an acoustic alarm system (105) is mounted on a lower portion of the front surface of the housing (100).
3. The vertical stratified soil lower line-breaking pole tower fault step-by-step voltage risk assessment system according to claim 2, wherein the projector (106) is connected to the bottom of the housing (100) through a fixing rod (109); the upper end of the fixed rod (109) is fixedly connected with the bottom of the shell (100) through a third screw (112) and a fourth screw (113); the lower end of the fixing rod (109) is fixedly connected with the projector (106) through a first screw (110) and a second screw (111).
4. The system for evaluating the step voltage risk of a vertical stratified soil underground broken line connection rod tower fault according to claim 1, further comprising a first angle steel type fastener (102) and a second angle steel type fastener (103), wherein the first angle steel type fastener (102) and the second angle steel type fastener (103) are both installed on the left side of the shell (100).
5. A method for evaluating fault step voltage risk of a vertical stratification soil lower broken line extension tower adopts the fault step voltage risk evaluation system of the vertical stratification soil lower broken line extension tower of any one of claims 1-4, and is characterized by comprising the following steps:
step one, calculating any point P of earth electrode soil area in faultmPotential value V ofPm：
The total circumference of the cross grounding device of the tower fixed by the evaluation system is set to be L, and the cross grounding device is divided into n sectionsUniform conductor, with leakage current of j-th conductor being IjHaving a length LjThen at any point P on the earth's surface around the towermThe generated potential VPmComprises the following steps:
in the formula, RTjThe contact resistance of the j section conductor; rPmjA mutual resistance equal to P when a unit current is applied to the j-th conductormThe potential of the dot; g is the number of calculation points; c is a correction coefficient;
RTj＝12.2182h0 0.76·ρ0 0.85·In(ρ1) (2)
in the formula, ρ1The resistivity of the left soil near the tower; because the grounding device is not completely contacted with the soil closely, a contact layer formed by soil particles and air gaps exists, rho0Is the contact layer resistivity; h is0Is the contact layer thickness;
the mutual resistance of the left soil area under the rectangular coordinate system is as follows:
the right soil area mutual resistance is:
in the formulas (3) and (4), the geometric center of the cross-shaped grounding device is taken as the origin of coordinates, the Z axis is vertical to the ground and faces downwards, the X axis is parallel to the power transmission line and points to the user side, and the Y axis rotates 90 degrees anticlockwise when the user looks from the sky to the earth surface; the method comprises the following steps of vertically dividing soil along an X axis, wherein the left side soil is arranged on one side of the X axis in the negative direction, the right side soil is arranged in the positive direction, and H is the distance from the geometric center of the grounding device to an interface; (x)j,yj,zj) The coordinates of the center point of the j section conductor; (x)m,ym,zm) For any point P on the groundmThe coordinates of (a); (x)mj’,ymj’,zmj’,zmj1’)＝(xm-xj,ym-yj,zm-zj,zm+zj)；ρ2Resistivity of the soil on the right side; hjThe distance from the center point of the j section of conductor to the interface is obtained;
second, the current value I flowing through the human body is measured by a potentiometer having two points P, Q at an arbitrary distance of 1m from the earth's surfaceP：
In the formula (6), VP、VQP, Q are potential values of two points respectively; rinIs a human body internal resistor; r0Is the human skin resistance; b is the equivalent grounding radius of the human body; ρ is the average resistivity of P, Q two points;
in the formula (7), (x)1,y1,z1)、(x2,y2,z2) P, Q two-point coordinates respectively taking the geometric center of the cross grounding device as the origin of coordinates; d is the maximum value of the distance from the two points P, Q to the center of the cross-shaped grounding device;
thirdly, dividing a step voltage danger area according to the bearable current of the human body:
when I isPWhen the current value is 100mA, D is calculated corresponding to P, Q two points1(ii) a All the same asPWhen D is 25mA, D is D2；IPWhen D is 6mA, D is D3；IPWhen 1mA, D is D4；
When I isP>100mA, i.e. D<D1The area is at first-class danger; when 25 is turned on<IP<100mA, i.e. D1<D<D2The area is at the same risk level; when 6 is<IP<25mA, i.e. D2<D<D3When this region isThird, the danger; when 1 is<IP<6mA, i.e. D3<D<D4Then, the area is at risk of four; when I isP<1mA, i.e. D>D4When, this area is a safe area.
6. The method for fault step voltage risk assessment of a line break and rod tower under vertical stratification soil according to claim 5, wherein the value of c is calculated by the following algorithm:
①, initializing, namely setting an evolution algebra counter u to be 0, setting a maximum evolution algebra G to be 100, and randomly generating 50 different c values as an initial population P (0);
② evaluation of individuals by calculating the fitness f (c) of each individual in the population according to the formula;
wherein, V'PmIs a point PmCalculating the potential of the real sample;
③ genetic operation, which comprises selecting, crossing and mutating according to the fitness of each individual in the population to generate new generation of individuals;
④, if u is less than or equal to G, u is equal to u +1, go to step ②, if u is greater than G, then the individual c with the maximum fitness obtained in the evolution process is used as the optimal solution output, and the calculation is terminated.
7. The method for vertical stratification soil sub-line break-extension tower fault step voltage risk assessment according to claim 5, characterized in that projector (106) displays five regions according to the third step with different color projection.
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