CN111239475B - Method and system for alarming step voltage of power-frequency follow current fault of reinforced concrete pole tower - Google Patents
Method and system for alarming step voltage of power-frequency follow current fault of reinforced concrete pole tower Download PDFInfo
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
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Abstract
The invention relates to a reinforced concrete pole tower power frequency follow current fault step voltage alarm method and system, and belongs to the technical field of power system ground analysis. The method comprises the steps of firstly calculating the potential value of a fault current at any point on the surface of a soil area near a tower, then obtaining the current value of a human body flowing through by using the potential difference of any two points on the earth surface with the distance of 1m, and finally dividing a step voltage danger area according to the bearable current of the human body. The invention can divide dangerous areas causing electric shock accidents of human bodies, alarm sound signals and light signals through the alarm system, and project the dangerous areas on the ground, thereby realizing the alarm of power-frequency follow current fault step voltage of the reinforced concrete pole tower.
Description
Technical Field
The invention belongs to the technical field of power system grounding analysis, and particularly relates to a method and a system for alarming step voltage of a reinforced concrete pole tower power frequency follow current fault.
Background
Most faults in the power system occur in the area of a power distribution network, most lines of the power system are outdoors, and the distribution is wide. The most common fault form of a power distribution system is a ground fault, which generally occurs in wet and rainy weather, a fault line can generate a step voltage on the ground surface around during the fault, and a cable line is widely applied nowadays, so that the capacitance current is increased during short circuit, the step voltage is correspondingly increased, and the personal health safety of peripheral workers and residents is seriously threatened.
The problem of the power frequency follow current fault of the distribution network is always solved. At present, many researches on power-frequency follow current faults of a distribution network are carried out at home and abroad, researchers in relevant fields of China study step voltages, simple researches are carried out on the step voltages and contact voltages when a line tower is grounded, and workers analyze step voltage calculation and deduce a calculation formula, but researches on an assessment alarm method of personal safety are lacked. In order to ensure the personal safety of workers and local residents, an intelligent alarm method is urgently needed, so that the danger of electric shock of people in a fault area can be evaluated, and the danger can be timely alarmed.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method and a system for alarming the step voltage of a power-frequency follow current fault of a reinforced concrete pole tower.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the method for alarming the power-frequency follow current fault step voltage of the reinforced concrete pole tower is characterized by comprising the following steps of:
step (1), calculating any point P of fault current on the surface of the soil area near the towerkPotential value V ofPk：
The total length of the square grounding device of the reinforced concrete tower is set to be L, the square grounding device is divided into M sections of conductors with the same size, and the leakage current of the j section of conductor is set to be IjHaving a length LjWhen P iskWhen the distance between the point and the j-th conductor exceeds 1.8L, the whole conductor is regarded as a point power supply OjThe section of conductor is at point PkThe value of the generated potential VPjk：
Wherein:
rnjk1＝rnjk2＝{(xk-xj)2+(yk-yj)2+[2h-βn]}1/2 (2)
rnjk3＝{(xk-xj)2+(yk-yj)2+[[2h-βn+zj]}1/2 (3)
rnjk4＝{(xk-xj)2+(yk-yj)2+[2h-βn-zj]}1/2 (4)
in the formulas (1) to (4), the geometric center of the square 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 is rotated by 90 degrees in a counterclockwise way by the X axis when viewed from the sky to the earth surface; horizontally dividing the soil along the Z axis, wherein the side close to the earth surface is surface soil, the side far away is deep soil, and h is the thickness of the surface soil; (x)k,yk,0)、(xj,yj,zj) Are respectively a point PkAnd OjThe coordinates of (a); sigma1Conductivity of surface soil; sigma2Conductivity of deep soil; r isjk、rjk' are each PkPoint and OjAnd the distance between its mirror images; alpha is alphan、βnIs a complex mirror image coefficient; r isnjk1、rnjk2、rnjk3、rnjk4Is the spatial distance; 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; c is a correction coefficient;
when potential calculation point PkWhen the distance between the section j and the section j conductor is not more than 1.8L, the conductor is segmented for the second time and is divided into m micro-conductor sections with the same size, and the section j conductor is arranged at the point PkThe value of the generated potential VPjk：
In the formula, G (O)j,Pk) Is a green function; l is an integral variable;
leakage current point P of whole towerkThe generated potential VPkComprises the following steps:
wherein g is the number of calculation points;
step (2) of using the potential of P, Q at two arbitrary points on the earth's surface at a distance of 1mThe difference is used to obtain the current value I flowing through the human bodyP：
In formulae (8) to (9), VP、VQP, Q for two points of potential; rinIs a human body internal resistor; r0Is the human skin resistance; b is the equivalent grounding radius of the human body; (x)1,y1,z1)、(x2,y2,z2) The coordinates of a point P and a point Q which take the geometric center of the square grounding device as the origin of coordinates are respectively arranged; d is the maximum value of the horizontal distance from the P, Q two points to the center of the square grounding device;
step (3), dividing the step voltage dangerous 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.
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, according to the calculation result in the step (3), an audible and visual alarm system is adopted for alarming, and a projection device is adopted for displaying five areas by using different colors for projection to warn.
Further, it is preferable that the value of c is calculated by the following algorithm:
firstly, initializing: 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);
secondly, individual evaluation: calculating the fitness f (c) of each individual in the population according to the formula;
wherein, V'PkIs a point PkCalculating the potential of the existing real sample;
③ genetic operation: according to the fitness of each individual in the group, carrying out selection, crossing and mutation operations to generate a new generation of individuals;
if u is less than or equal to G, if u is equal to u +1, the step goes to; if u is larger 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 invention also provides a reinforced concrete pole tower power frequency follow current fault step voltage alarm system, which comprises a current sensor, a fault alarm lamp, a polyphonic loudspeaker, projection equipment, a power supply module, a calculation processing module and an amplifying circuit module;
the power supply module is connected with the calculation processing module;
the calculation processing module is respectively connected with the current sensor, the amplifying circuit module, the fault alarm lamp and the projection equipment;
the amplifying circuit module is also connected with the multi-tone loudspeaker;
the calculation processing module is used for calculating according to data acquired by the current sensor by adopting the reinforced concrete pole tower power frequency follow current fault step voltage alarm method of claim 1; then according to the calculation result, light alarm is carried out through a fault alarm lamp, and each area is projected through projection equipment to carry out warning;
the amplifying circuit module is used for amplifying the alarm signal transmitted by the calculation processing module and then transmitting the alarm signal to the multi-tone loudspeaker for sound alarm.
Further, it is preferable that the current sensor is fixed at a tower foot of the tower.
Further, preferably, the system further comprises a wireless transmission module, wherein the wireless transmission module is connected with the calculation processing module and is used for wirelessly transmitting the fault information to a power grid maintenance department according to the calculation result.
The method is mainly applied to calculating the surface potential distribution when the short-circuit fault of the line disconnection and pole connection tower occurs in the distribution network and giving alarms of different levels according to different step voltages.
Compared with the prior art, the invention has the beneficial effects that:
1) the potential of any point of the earth surface around the transmission line tower can be effectively 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) a step voltage dangerous area can be divided by step voltage and human body current;
4) the alarm system can give sound and light alarm when the fault occurs, and the rings with different colors are projected according to the danger level, so that the method is novel and effective.
Drawings
FIG. 1 is a schematic view of the present invention in use;
FIG. 2 is a schematic structural diagram of a reinforced concrete pole tower power frequency follow current fault step voltage alarm system of the present invention;
FIG. 3 is a schematic diagram of the overall structure of a reinforced concrete pole tower power frequency follow current fault step voltage alarm system of the present invention;
1, a first reinforced concrete tower; 2. a second reinforced concrete tower; 3. a third reinforced concrete 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 square grounding device; 12. a second square grounding device; 13. a third square grounding device; 14. surface soil; 15. an alarm system; 16. deep soil;
100. a housing; 101. a current sensor; 102. a first fixing device; 103. a second fixing device; 104. a fault warning lamp; 105. a polyphonic loudspeaker; 106. a projection device; 107. a solar panel; 108. a wireless transmission module; 109. a suspension rod; 110. a first screw; 111. a second screw; 112. a third screw; 113. a fourth screw; 200. an internal control circuit; 201. a power supply module; 202. a calculation processing module; 203. a lithium battery; 204. A power supply control circuit; 205. and an amplifying circuit 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.
The method for alarming the step voltage of the power-frequency follow current fault of the reinforced concrete pole tower comprises the following steps of:
step (1), calculating any point P of fault current on the surface of the soil area near the towerkPotential value V ofPk：
The total length of the square grounding device of the reinforced concrete tower is set to be L, the square grounding device is divided into M sections of conductors with the same size, and the leakage current of the j section of conductor is set to be IjHaving a length LjWhen P iskWhen the distance between the point and the j-th conductor exceeds 1.8L, the whole conductor is regarded as a point power supply OjThe section of conductor is at point PkGeneratingPotential value V ofPjk：
Wherein:
rnjk1＝rnjk2＝{(xk-xj)2+(yk-yj)2+[2h-βn]}1/2 (2)
rnjk3＝{(xk-xj)2+(yk-yj)2+[2h-βn+zj]}1/2 (3)
rnjk4＝{(xk-xj)2+(yk-yj)2+[2h-βn-zj]}1/2 (4)
in the formulas (1) to (4), the geometric center of the square 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 is rotated by 90 degrees in a counterclockwise way by the X axis when viewed from the sky to the earth surface; horizontally dividing the soil along the Z axis, wherein the side close to the earth surface is surface soil, the side far away is deep soil, and h is the thickness of the surface soil; (x)k,yk,0)、(xj,yj,zj) Are respectively a point PkAnd OjThe coordinates of (a); sigma1Conductivity of surface soil; sigma2Conductivity of deep soil; r isjk、rjk' are each PkPoint and OjAnd the distance between its mirror images; alpha is alphan、βnIs a complex mirror image coefficient; r isnjk1、rnjk2、rnjk3、rnjk4Is the spatial distance; 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; c is a correction coefficient;
when potential calculation point PkWhen the distance between the conductor and the jth section is not more than 1.8L, the conductor is segmented for the second time and divided intom sections of equal size micro-conductor, the j-th section of conductor being at point PkThe value of the generated potential VPjk：
In the formula, G (O)j,Pk) Is a green function; l is an integral variable;
leakage current point P of whole towerkThe generated potential VPkComprises the following steps:
wherein g is the number of calculation points;
the value of c is calculated by the following algorithm:
firstly, initializing: 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);
secondly, individual evaluation: calculating the fitness f (c) of each individual in the population according to the formula;
wherein, V'PkIs a point PkCalculating the potential of the real sample;
③ genetic operation: according to the fitness of each individual in the population, adopting MATLAB default selection, crossing and mutation operations to generate a new generation of individuals;
if u is less than or equal to G, if u is equal to u +1, the step goes to; if u is larger than G, outputting the individual c with the maximum fitness obtained in the evolution process as an optimal solution, and stopping calculation;
step (2), the potential difference of any two points P, Q on the earth surface with the distance of 1m is used for obtaining the current value I flowing through the human bodyP：
In formulae (8) to (9), VP、VQP, Q for two points of potential; rinIs a human body internal resistor; r0Is the human skin resistance; b is the equivalent grounding radius of the human body; (x)1,y1,z1)、(x2,y2,z2) The coordinates of a point P and a point Q which take the geometric center of the square grounding device as the origin of coordinates are respectively arranged; d is the maximum value of the horizontal distance from the P, Q two points to the center of the square grounding device;
step (3), dividing the step voltage dangerous 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.
And (4) according to the calculation result of the step (3), alarming by adopting an audible and visual alarm system, and displaying five areas for warning by adopting projection equipment through projection with different colors.
The reinforced concrete pole tower power frequency follow current fault step voltage alarm system comprises a current sensor 101, a fault alarm lamp 104, a multitone loudspeaker 105, a projection device 106, a power supply module 201, a calculation processing module 202 and an amplifying circuit module 205;
the power supply module 201 is connected with the calculation processing module 202;
the calculation processing module 202 is respectively connected with the current sensor 101, the amplifying circuit module 205, the fault warning lamp 104 and the projection device 106;
the amplifying circuit module 205 is further connected with the polyphonic loudspeaker 105;
the calculation processing module 202 is configured to perform calculation by using the reinforced concrete pole tower power frequency follow current fault step voltage alarm method according to claim 1 according to data acquired by the current sensor 101; then, according to the calculation result, light alarm is carried out through the fault alarm lamp 104, and each area is projected through the projection equipment 106 for warning;
the amplifying circuit module 205 is used for amplifying the signal transmitted from the calculation processing module 202, and then performing an audio alarm through the polyphonic speaker 105.
The current sensor 101 is fixed at the tower foot of the tower.
The system further comprises a wireless transmission module 108, wherein the wireless transmission module 108 is connected with the calculation processing module 202 and is used for wirelessly transmitting the fault information to a power grid maintenance department according to the calculation result.
Examples of the applications
As shown in fig. 1, a first reinforced concrete tower 1, a second reinforced concrete tower 2 and a third reinforced concrete tower 3 are connected with each other through 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, tower feet are grounded through a first square-shaped grounding device 11, a second square-shaped grounding device 12 and a third square-shaped grounding device 13 respectively, the first transmission line 4, the fourth transmission line 9, the second transmission line 5 and the fifth transmission line 10 are B, C two phases under the normal working condition of the transmission lines, the third transmission line 8 is an a phase under the normal working condition of the transmission lines, the first broken line 6 and the second broken line 7 are an a phase under the broken state of the transmission lines, the first broken line 6 is suspended, the second broken line 7 is lapped on the second reinforced concrete tower 2 to cause a single-phase short circuit fault, and the current flows into the ground along the second square-shaped grounding device 12;
as shown in fig. 2 and 3, the alarm system 15 includes a housing 100, a current sensor 101, a fault warning lamp 104, a polyphonic horn 105, a projection device 106, a wireless transmission module 108, a power supply module 201, a calculation processing module 202, and an amplifying circuit module 205;
the current sensor 101 is fixed at the tower foot of the tower;
the power supply module 201 is connected with the calculation processing module 202;
the calculation processing module 202 is respectively connected with the current sensor 101, the amplifying circuit module 205, the fault warning lamp 104 and the projection device 106;
the amplifying circuit module 205 is further connected with the polyphonic loudspeaker 105;
the calculation processing module 202 is configured to perform calculation by using the reinforced concrete pole tower power frequency follow current fault step voltage alarm method according to claim 1 according to data acquired by the current sensor 101; then, according to the calculation result, light alarm is carried out through the fault alarm lamp 104, and each area is projected on the ground through the projection equipment 106 for warning;
the amplifying circuit module 205 is used for amplifying the signal transmitted from the calculation processing module 202, and then performing sound alarm through the multi-tone loudspeaker 105;
the wireless transmission module 108 is connected to the calculation processing module 202, and is configured to wirelessly transmit the fault information to a power grid maintenance department according to the calculation result.
The power supply module 201 comprises a solar panel 107, a lithium battery 203 and a power supply control circuit 204, which jointly supply power to the risk assessment system 15 of the invention;
the solar panel 107 and the power supply control circuit 204 are respectively connected with the lithium battery 203;
The projection device 106 is connected to the bottom of the housing 100 by a suspension rod 109; the upper end of the suspension 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 suspension rod 109 is fixedly connected with the projection device 106 through a first screw 110 and a second screw 111. I.e. the projection device 106 is suspended directly below the housing 100;
the first fixing device 102 and the second fixing device 103 are arranged on the left side of the shell 100 and fixed on the second reinforced concrete pole tower 2.
The wireless transmission module 108, the power supply module 201, the calculation processing module 202 and the amplifying circuit module 205 together form an internal control circuit 200.
Preferably, the current sensor 101 is a rogowski coil current sensor. The current sensor 101 transmits the incoming current signal to the calculation processing module 202 through the BNC connector.
Firstly, calculating any point P of fault current on the surface of soil area near a towerkPotential value V ofPk：
When a single-phase connection No. two reinforced concrete pole towers 2 has a fault in a line, fault current flows in a scattered manner to horizontally layered surface soil 14 and deep soil 16 along a No. two square grounding device 12, the total length of the No. two square grounding device 12 is set to be L, the two square grounding device is divided into M sections of conductors with the same size, and the leakage current of the j section of conductor is IjHaving a length LjWhen P iskWhen the distance between the point and the j-th conductor exceeds 1.8L, the whole conductor is regarded as a point power supply OjThe section of conductor is at point PkThe value of the generated potential VPjk：
Wherein:
rnjk1＝rnjk2＝{(xk-xj)2+(yk-yj)2+[2h-βn]}1/2 (11)
rnjk3＝{(xk-xj)2+(yk-yj)2+[2h-βn+zj]}1/2 (12)
rnjk4＝{(xk-xj)2+(yk-yj)2+[2h-βn-zj]}1/2 (13)
in the formulas (10) to (13), the geometric center of the square 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 is rotated by 90 degrees in a counterclockwise way by the X axis when viewed from the sky to the earth surface; horizontally dividing the soil along the Z axis, wherein the side close to the earth surface is surface soil, the side far away is deep soil, and h is the thickness of the surface soil; (x)k,yk,0)、(xj,yj,zj) Are respectively a point PkAnd OjThe coordinates of (a); sigma1Conductivity of surface soil; sigma2Conductivity of deep soil; r isjk、rjk' are each PkPoint and OjAnd the distance between its mirror images; alpha is alphan、βnIs a complex mirror image coefficient; r isnjk1、rnjk2、rnjk3、rnjk4Is the spatial distance; 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; c is a correction coefficient;
when potential calculation point PkWhen the distance between the section j and the section j conductor is not more than 1.8L, the conductor is segmented for the second time and is divided into m micro-conductor sections with the same size, and the section j conductor is arranged at the point PkThe value of the generated potential VPjk：
In the formula, G (O)j,Pk) Is a green function; l is an integral variable;
leakage current point P of No. 2 reinforced concrete pole towerkThe generated potential VPkComprises the following steps:
wherein g is the number of calculation points;
the value of c is calculated by the following algorithm:
firstly, initializing: 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);
secondly, individual evaluation: calculating the fitness f (c) of each individual in the population according to the formula;
wherein, V'PkIs a point PkCalculating the potential of the real sample with the unit of V;
③ genetic operation: according to the fitness of each individual in the population, adopting MATLAB default selection, crossing and mutation operations to generate a new generation of individuals;
if u is less than or equal to G, if u is equal to u +1, the step goes to; if u is larger than G, outputting the individual c with the maximum fitness obtained in the evolution process as an optimal solution, and stopping calculation;
secondly, the potential difference of any two points P, Q on the earth's surface with the distance of 1m is used to obtain the current value I flowing through the human bodyP：
In the formula (17), VP、VQP, Q, the potentials of the two points are respectively, and the unit is V; rinThe resistance of the inside of the human body is 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; in the formula (18), (x)1,y1,z1)、(x2,y2,z2) Coordinates of a point P and a point Q which take the second square grounding device 12 as a coordinate origin point are respectively provided; d is the maximum value of the horizontal distance from P, Q two points to the center of the second square-shaped grounding device 12, and the unit is m;
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.
Setting L as 1.2M, M as 12, Ij＝5A，ρ0＝500Ω·m，σ1＝(1/120)S/m，σ2＝(1/100)S/m， h0The geometric center of the square grounding device II is set to be (0,0,0.5) and V of 30 points is calculated when h is 0.001m, h is 1m, and g is 30PkAnd the value of the parameter c is 0.9376 after calculation by an algorithm, coordinates of P, Q two points are selected as (5,0,0) and (6,0,0), and R is obtained through calculationTj＝60.428215794561230Ω，VP＝170. 314353610834V，VQAssuming R143.079628001445Vin＝500Ω、R0＝250Ω、b＝0.08m， IP19.807073170464720mA, D6 m. Is composed of (6)<IP<25mA, and the area is three dangerous areas.
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 (6)
1. The method for alarming the power-frequency follow current fault step voltage of the reinforced concrete pole tower is characterized by comprising the following steps of:
step (1), calculating any point P of fault current on the surface of the soil area near the towerkPotential value V ofPk：
The total length of the square grounding device of the reinforced concrete tower is set to be L, the square grounding device is divided into M sections of conductors with the same size, and the leakage current of the j section of conductor is set to be IjHaving a length LjWhen P iskWhen the distance between the point and the j-th conductor exceeds 1.8L, the whole conductor is regarded as a point power supply OjThe section of conductor is at point PkThe value of the generated potential VPjk：
Wherein:
rnjk1＝rnjk2＝{(xk-xj)2+(yk-yj)2+[2h-βn]}1/2 (2)
rnjk3＝{(xk-xj)2+(yk-yj)2+[[2h-βn+zj]}1/2 (3)
rnjk4＝{(xk-xj)2+(yk-yj)2+[2h-βn-zj]}1/2 (4)
in the formulas (1) to (4), the geometric center of the square grounding device is used as the origin of coordinates, and the Z axisThe power transmission line is vertical to the ground and faces downwards, the X axis is parallel to the power transmission line and points to a user side, and the Y axis rotates 90 degrees anticlockwise when the user looks from the sky to the earth; horizontally dividing the soil along the Z axis, wherein the side close to the earth surface is surface soil, the side far away is deep soil, and h is the thickness of the surface soil; (x)k,yk,0)、(xj,yj,zj) Are respectively a point PkAnd OjThe coordinates of (a); sigma1Conductivity of surface soil; sigma2Conductivity of deep soil; r isjk、rjk' are each PkPoint and OjAnd the distance between its mirror images; alpha is alphan、βnIs a complex mirror image coefficient; r isnjk1、rnjk2、rnjk3、rnjk4Is the spatial distance; 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; c is a correction coefficient;
when potential calculation point PkWhen the distance between the section j and the section j conductor is not more than 1.8L, the conductor is segmented for the second time and is divided into m micro-conductor sections with the same size, and the section j conductor is arranged at the point PkThe value of the generated potential VPjk：
In the formula, G (O)j,Pk) Is a green function; l is an integral variable;
leakage current point P of whole towerkThe generated potential VPkComprises the following steps:
wherein g is the number of calculation points;
step (2), the potential difference of any two points P, Q on the earth surface with the distance of 1m is used for obtaining the current value I flowing through the human bodyP：
In formulae (8) to (9), VP、VQP, Q for two points of potential; rinIs a human body internal resistor; r0Is the human skin resistance; b is the equivalent grounding radius of the human body; (x)1,y1,z1)、(x2,y2,z2) The coordinates of a point P and a point Q which take the geometric center of the square grounding device as the origin of coordinates are respectively arranged; d is the maximum value of the horizontal distance from the P, Q two points to the center of the square grounding device;
step (3), dividing the step voltage dangerous 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.
2. The reinforced concrete pole tower power frequency follow current fault step voltage alarm method as claimed in claim 1, wherein according to the calculation result of step (3), an acousto-optic alarm system is adopted for alarming, and projection equipment is adopted for displaying five areas by using different colors for warning.
3. The reinforced concrete pole tower power frequency follow current fault step voltage alarm method as claimed in claim 1, wherein the value c is calculated by the following algorithm:
firstly, initializing: 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);
secondly, individual evaluation: calculating the fitness f (c) of each individual in the population according to the formula;
wherein, V'PkIs a point PkCalculating the potential of the existing real sample;
③ genetic operation: according to the fitness of each individual in the group, carrying out selection, crossing and mutation operations to generate a new generation of individuals;
if u is less than or equal to G, if u is equal to u +1, the step goes to; if u is larger 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.
4. The reinforced concrete pole tower power frequency follow current fault step voltage alarm system is characterized by comprising a current sensor, a fault alarm lamp, a multitone loudspeaker, projection equipment, a power supply module, a calculation processing module and an amplifying circuit module;
the power supply module is connected with the calculation processing module;
the calculation processing module is respectively connected with the current sensor, the amplifying circuit module, the fault alarm lamp and the projection equipment;
the amplifying circuit module is also connected with the multi-tone loudspeaker;
the calculation processing module is used for calculating according to data acquired by the current sensor by adopting the reinforced concrete pole tower power frequency follow current fault step voltage alarm method of claim 1; then according to the calculation result, light alarm is carried out through a fault alarm lamp, and each area is projected through projection equipment to carry out warning;
the amplifying circuit module is used for amplifying the alarm signal transmitted by the calculation processing module and then transmitting the alarm signal to the multi-tone loudspeaker for sound alarm.
5. The reinforced concrete pole tower power frequency follow current fault step voltage alarm system of claim 4, wherein: the current sensor is fixed at the tower foot of the tower.
6. The reinforced concrete pole tower power frequency follow current fault step voltage alarm system of claim 4, wherein: the wireless transmission module is connected with the calculation processing module and used for wirelessly transmitting the fault information to a power grid maintenance department according to the calculation result.
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