CN104897993B - A kind of overhead transmission line current-carrying capacity appraisal procedure - Google Patents

Abstract

The invention discloses a kind of overhead transmission line current-carrying capacity appraisal procedure, the mounted angle sensor on shaft tower, inclination angle is hung by wire and angle of wind deflection calculates conductor temperature, pass through temperature sensor measurement environment temperature and intensity of sunshine, by installing current sensor measurement wire Real-time Load on the line, combined influence of the microclimate conditions such as wind speed and direction to wire is represented using heat transfer coefficient, finally according to conductor temperature model, the real-time maximum carrying capacity for assessing wire is calculated.Present invention reduces the error of existing conductor temperature measuring method, the appliance arrangement set-up time is shortened, reduce data analysis complexity, it is to avoid the problem of wind speed and direction measurement is inaccurate, add the reliability of current carrying capacity of conductor calculating.

Description

A kind of overhead transmission line current-carrying capacity appraisal procedure

Technical field

The present invention relates to power transmission network current-carrying capacity technical field, specifically a kind of overhead transmission line current-carrying capacity assessment side Method.

Background technology

As China's economy is skyrocketed through, electricity needs rapidly rises, and from the seventies in last century, China just steps into The situations of power shortages.Meanwhile, the construction of power transmission network again by construction period length, the first stage of investment is huge, expropriation of land is difficult, ring The factors such as guarantor's problem are restricted, and especially on the nervous big and medium-sized cities periphery of land used, newly-built transmission line of electricity is extremely difficult.In this background Under, improving existing electric network transportation ability turns into one of urgent problem to be solved.

For existing line, on the premise of not changing existing network structure and ensuring power grid security reliability service, Assessed in real time according to ambient parameter (environment temperature, wind speed, wind direction, intensity of sunshine etc.), conductor temperature and the wire load of wire The maximum carrying capacity of transmission line of electricity, can be on the basis of transmission line safety stable operation be ensured, increase line to greatest extent Road-load flow, allows many newly-built circuits to postpone or not build temporarily, can largely alleviate the transmission of electricity after load abruptly increase Bottleneck problem.

In existing transmission line of electricity current-carrying capacity assessment system, for conductor temperature, typically there are following several measuring methods：Pass through Sensor direct measurement conductor temperature, because wire is typically very long, residing meteorological condition is not completely the same, therefore measures a certain The temperature of point is difficult the samming for representing wire, and sensor surveys conductive line surfaces temperature there is also some errors with internal temperature； By tension sensor measure traverse line tension force, conductor temperature is calculated using wire tension temperature foh curve, this method can be with Wire samming is relatively accurately obtained, but power failure for a long time is needed in primary side installation tension meter, Operation of Electric Systems is caused Certain influence；By imaging sensor measure traverse line sag, conductor temperature is tried to achieve using sag temperature curve, this method is only needed Several cameras are installed below wire, but amount of calculation is larger in image procossing and there is certain error.For wire current-carrying Computation model is measured, climate model is used existing assessment system more, but the selection of weather conditions is more general, it is and micro- residing for wire It is generally large to there is wind speed wind vector in certain deviation, and required calculating parameter in weather conditions, it is difficult to accurate measurement.

Therefore the system calculates conductor temperature using obliquity sensor, based on conductor temperature model, utilizes heat transfer coefficient The combined influence of environment temperature, wind speed and direction to wire is represented, using temperature sensor measurement environment temperature and intensity of sunshine, is led to The current sensor measurement load current of hanging wire is crossed, assesses and leads using conductor temperature, environment temperature, intensity of sunshine, load current The real-time current-carrying capacity of line, equipment install convenient, without measuring wind speed and direction, it is to avoid wind speed and direction indeterminable problem, are improved Calculate accuracy.

The content of the invention

It is an object of the invention to overcome above-mentioned the deficiencies in the prior art, it is proposed that one kind is based on wire microclimate condition The overhead transmission line current-carrying capacity real time evaluating method of (environment temperature, intensity of sunshine) and wire measurement of dip angle.

The principle of the present invention：

The current-carrying capacity of overhead transmission line mainly with the wire itself such as environmental factor and conductor temperature, conductor material size Factor is relevant.It calculates the main steady-state heat balance equation according to wire, as follows

Q_r+Q_f=Q_s+I²R_t' (1)

Wherein Q_rFor heat loss through radiation power, Q_fFor heat loss through convection power, Q_sFor sunshine Endothermic power, I²R_t' exchanged for wire The heating power of resistance.After it is determined that wire type is wire parameters, the physical significance of four kinds of power and calculating in (1) formula It is as follows.

Heat loss through radiation power Q_rThe heat radiation power of conductive line surfaces is illustrated, with wire inherent parameters, conductor temperature T_c, ring Border temperature T_aRelevant, specific calculate sees below formula.

Q_r=π DE₁S₁[(T_c+273)⁴-(T_a+273)⁴] (2)

Wherein, D is wire diameter；E₁For the heat-radiation heat-dissipating coefficient of conductive line surfaces, in China's standard, 0.9 is typically taken；S₁ For Si Tefan-Bao Erciman constants, 5.67 × 10 are taken^-8, W/m²；T_a、T_cFor conductor temperature and environment temperature, DEG C.

Sunshine Endothermic power Q_sThe power of wire counterglow radiation absorption is illustrated, is had with the size and intensity of sunshine of wire Close.

Q_s=α_SJ_SD (3)

Wherein, α_SIt is typically equal with wire radiation coefficient in China's standard for the heat absorption coefficient of conductive line surfaces；J_sFor sunshine Intensity, for the sake of guarding, in China's standard, is typically taken as 1000W/m²。

The heating power I of wire AC resistance²R_t' by wire stable state current-carrying capacity I and wire AC resistance calculate and Come, conductor temperature is T_cWhen AC resistance R (T_c) and conductor temperature T_cIt is relevant：

R(T_c)=(1+k) R₂₀[1+α₂₀(T_c-20)] (4)

Wherein, k is the skin effect coefficient of wire, relevant with the cross-sectional area of wire, when cross-sectional area is not more than 400mm²When, take k=0.0025 to be more than 400mm²When, take k=0.01；R₂₀Material temperature coefficient during for 20 DEG C of wire, for Aluminum, can take 0.00403/ DEG C.

Heat loss through convection power Q_fBy conductor temperature T_c, environment temperature T_aCalculated with heat transfer coefficient h (t), such as following formula.

Q_f=h (t) (T_c-T_a) (5)

Wherein, heat transfer coefficient h (t) illustrates the combined influence of environment temperature, wind speed, wind direction to heat loss through convection power, Not accurate enough when being in the measurement of wind speed and direction, conductor temperature model can avoid the error that it brings well.

In known lead current loads electric current I₀, conductor temperature T_c, environment temperature T_a, intensity of sunshine J_SWith wire itself ginseng , can be by bringing following formula into and calculating h (t) (2), (3), (4) formula during number.

When the wind speed change of environment temperature is little, heat transfer coefficient h (t) change is extremely small, substantially thousand/ Within one.Corresponding heat transfer coefficient when therefore can take conductor temperature for maximum allowable temperature 70 C.

The technical solution of the present invention is as follows：

A kind of overhead transmission line current-carrying capacity appraisal procedure, its feature is that this method comprises the following steps：

Step S1, the side of wire mounted angle sensor on steel tower, to be hung in measure traverse line upright projection plane Inclination angle theta_AWith angle of wind deflection η；Current sensor is hung on wire, the load current I to measure traverse line₀；Temperature is installed on steel tower Sensor is spent, to measuring environment temperature T_aWith intensity of sunshine J_s；

Step S2, chooses Lead status when wire is unloaded, load current is zero I=0 as original state, i.e., known shape State, environment temperature is measured for T using temperature sensor_a0, conductor temperature now should be equal to environment temperature, i.e. T_c0=T_a0, utilize Initial suspension inclination angle theta in obliquity sensor measure traverse line upright projection plane_A0With initial angle of wind deflection η₀；

In wire normal operating condition, that is, state to be asked when load current is not zero, measures real-time using obliquity sensor Wire hangs inclination angle theta_A1With real-time angle of wind deflection η₁, it is T using temperature sensor measurement real time environment temperature_a1；

Step S3, calculates the wire horizontal stress σ of initial and real-time status₀And σ₁, formula is as follows：

In formula, θ_A0And θ_A1For initial and real-time status the suspension inclination angle of wire, l is line span, and β is high angular difference, can be Found in the design parameter of this circuit, γ_vTo be vertical than carrying, calculated by following formula

Wherein, q is unit length wire quality, and S is sectional area of wire；

Step S4, calculates the wire of initial and real-time status comprehensively than carrying γ₀And γ₁, formula is as follows：

In formula, η₀And η₁For the wire angle of wind deflection of original state and real-time status；

Step S5, calculates wire real time temperature T_c1, formula is as follows：

Wherein, σ₀And σ₁For the horizontal stress of initial and real-time status；γ₀And γ₁Wire for initial and real-time status is comprehensive Composition and division in a proportion is carried；η₀And η₁For the wire angle of wind deflection of initial and real-time status；T_c0And T_c1For the conductor temperature under initial and real-time status； α is conductor temperature linear expansion coefficient；E is coefficient of elasticity；

Step S6, utilizes the Real-time Load I of current sensor measurement wire₀, it is real-time using temperature sensor measurement wire Environment temperature T_a1And intensity of sunshine J_s, the wire heat transfer coefficient h (t) of current environmental condition is calculated, formula is as follows：

In formula, I₀For wire Real-time Load electric current, T_c1、T_a1For wire real time temperature and environment real time temperature, R (T_c1) lead Line temperature is T_c1When AC resistance, Q_r(T_c1,T_a1) it is heat loss through radiation power, Q_sFor sunshine Endothermic power；

Step S7, with wire maximum permissible temperature T_maxReplace wire real time temperature T_c, calculate current state lower wire maximum Current-carrying capacity I_max, formula is as follows：

According to China code wire maximum permissible temperature T_maxFor 70 DEG C or 80 DEG C.

Compared with prior art, the beneficial effects of the invention are as follows：

1) wire temperature is obtained by the suspension inclination angle and angle of wind deflection of crossing the obliquity sensor measure traverse line being arranged at shaft tower Degree, by temperature sensor measurement environment temperature and intensity of sunshine, by installing current sensor measurement wire on the line Real-time Load, finally brings conductor temperature, load, environment temperature and intensity of sunshine into conductor temperature model real-time to assess wire Peak load, improves the precision of conductor temperature calculating.

2) error of existing conductor temperature measuring method is reduced, data analysis complexity is reduced, wire load is added The reliability of flow rate calculation.

3) the appliance arrangement set-up time is shortened, it is to avoid equipment, which to be installed, have a power failure for a long time and wind speed and direction measures inaccurate The problem of, have a good application prospect.

Brief description of the drawings

Fig. 1 is scheme of installation of the present invention；

Fig. 2 is the not contour overhead transmission line windage yaw force diagram of hitch point；

Fig. 3 is overhead transmission line current-carrying capacity evaluation process schematic diagram.

Embodiment

The present invention is described in further detail below in conjunction with the accompanying drawings.

A kind of overhead transmission line current-carrying capacity appraisal procedure, comprises the following steps：

Step S1, as shown in figure 1, the side of wire mounted angle sensor on steel tower, to measure the outstanding of wire in Fig. 2 Hang inclination angle theta_AWith angle of wind deflection η；Current sensor is suspended on wire, the load current I of measure traverse line₀；Temperature sensor is arranged on On steel tower, measuring environment temperature T_aWith intensity of sunshine J_s。

Step S2, chooses wire zero load, i.e., Lead status when load current is zero (I=0) is (known as original state State), environment temperature is measured for T using temperature sensor_a0, conductor temperature now should be equal to environment temperature, i.e. T_c0=T_a0, Utilize initial suspension inclination angle theta in obliquity sensor measure traverse line upright projection plane_A0With initial angle of wind deflection η₀；

In wire normal operating condition (state to be asked), i.e., when load current is not zero, measure real using obliquity sensor When wire suspension inclination angle theta_A1With real-time angle of wind deflection η₁, it is T using temperature sensor measurement real time environment temperature_a1；

Step S3, calculates the wire horizontal stress σ of initial and real-time status₀And σ₁, formula is as follows：

In formula, θ_A0And θ_A1For initial and real-time status the suspension inclination angle of wire, l is line span, and β is high angular difference, is such as schemed Shown in 2, it can be found in the design parameter of this circuit；γ_vTo be vertical than carrying, calculated by following formula

Wherein, q is unit length wire quality；S is sectional area of wire；

Step S4, calculates the wire of initial and real-time status comprehensively than carrying γ₀And γ₁, formula is as follows：

In formula, η₀And η₁For the wire angle of wind deflection of original state and real-time status；

Step S5, calculates wire real time temperature T_c1, formula is as follows：

Wherein, σ₀And σ₁For the horizontal stress of initial and real-time status；γ₀And γ₁Wire for initial and real-time status is comprehensive Composition and division in a proportion is carried；η₀And η₁For the wire angle of wind deflection of initial and real-time status；T_c0And T_c1For the conductor temperature under initial and real-time status； α is conductor temperature linear expansion coefficient；E is coefficient of elasticity.

Step S6, utilizes the Real-time Load I of current sensor measurement wire₀, it is real-time using temperature sensor measurement wire Environment temperature T_a1And intensity of sunshine J_s, the wire heat transfer coefficient h (t) of current environmental condition is calculated, formula is as follows：

In formula, I₀For wire Real-time Load electric current, T_c1, T_a1For wire real time temperature and environment real time temperature, R (T_c1) lead Line temperature is T_c1When AC resistance, Q_r(T_c1,T_a1) it is heat loss through radiation power, Q_sFor sunshine Endothermic power；

Step S7, with wire maximum permissible temperature T_maxReplace wire real time temperature T_c, take in the present embodiment the conductor temperature to be Corresponding heat transfer coefficient during maximum allowable temperature 70 C,

h₇₀(t)≈h(t)

Calculate current state lower wire maximum carrying capacity I_max, formula is as follows：

It should be noted last that, the above embodiments are merely illustrative of the technical solutions of the present invention and it is unrestricted, although ginseng The present invention is described in detail according to preferred embodiment, it will be understood by those within the art that, can be to invention Technical scheme is modified or equivalent, and without departing from the spirit and scope of technical solution of the present invention, it all should cover Among scope of the presently claimed invention.

Claims (1)

1. a kind of overhead transmission line current-carrying capacity appraisal procedure, it is characterised in that this method comprises the following steps：

Step S1, the side of wire mounted angle sensor on steel tower, to hang inclination angle theta in measure traverse line upright projection plane_A With angle of wind deflection η；Current sensor is hung on wire, the load current I to measure traverse line₀；Temperature is installed on steel tower to pass Sensor, to measuring environment temperature T_aWith intensity of sunshine J_s；

Step S2, chooses Lead status when wire is unloaded, load current is zero I=0 as original state, i.e. known state, Environment temperature is measured for T using temperature sensor_a0, conductor temperature now should be equal to environment temperature, i.e. T_c0=T_a0, using inclining Initial suspension inclination angle theta in angle transducer measure traverse line upright projection plane_A0With initial angle of wind deflection η₀；

In wire normal operating condition, that is, when load current is not zero, real-time wire is measured using obliquity sensor for state to be asked Hang inclination angle theta_A1With real-time angle of wind deflection η₁, it is T using temperature sensor measurement real time environment temperature_a1；

Step S3, calculates the wire horizontal stress σ of initial and real-time status₀And σ₁, formula is as follows：

$\tan {\mathrm{\θ}}_{A0}=\frac{{\mathrm{\γ}}_{v}l}{{2\mathrm{\σ}}_0\cos \mathrm{\β}}-\tan \mathrm{\β},$

$\tan {\mathrm{\θ}}_{A1}=\frac{{\mathrm{\γ}}_{v}l}{{2\mathrm{\σ}}_1\cos \mathrm{\β}}-\tan \mathrm{\β}$

In formula, θ_A0And θ_A1For initial and real-time status the suspension inclination angle of wire, l is line span, and β is high angular difference, can be at this Found in the design parameter of circuit, γ_vTo be vertical than carrying, calculated by following formula

${\mathrm{\γ}}_v=\frac{9.80665q}{\text{S}}$

Wherein, q is unit length wire quality, and S is sectional area of wire；

Step S4, calculates the wire of initial and real-time status comprehensively than carrying γ₀And γ₁, formula is as follows：

${\mathrm{\γ}}_0=\frac{{\mathrm{\γ}}_v}{\cos {\mathrm{\η}}_0},$

${\mathrm{\γ}}_1=\frac{{\mathrm{\γ}}_v}{\cos {\mathrm{\η}}_1}$

In formula, η₀And η₁For the wire angle of wind deflection of original state and real-time status；

Step S5, calculates wire real time temperature T_c1, formula is as follows：

$\begin{array}{c}{\mathrm{\σ}}_1-\frac{E{\mathrm{\γ}}_1^2{l}^2{\cos }^3\mathrm{\β}}{24{\mathrm{\σ}}_1^2}(1+{\tan }^2\mathrm{\β}{\sin }^2{\mathrm{\η}}_1)\\ =-\mathrm{\α}E\cos \mathrm{\β}(T_{c1}-T_{c0})+{\mathrm{\σ}}_0-\frac{{\mathrm{E\γ}}_0^2{l}^2{\cos }^3\mathrm{\β}}{{24\mathrm{\σ}}_0^2}(1+{\tan }^2\mathrm{\β}{\sin }^2{\mathrm{\η}}_0)\end{array}$

Wherein, σ₀And σ₁For the horizontal stress of initial and real-time status；γ₀And γ₁Comprehensively compare for the wire of initial and real-time status Carry；η₀And η₁For the wire angle of wind deflection of initial and real-time status；T_c0And T_c1For the conductor temperature under initial and real-time status；α is Conductor temperature linear expansion coefficient；E is coefficient of elasticity；

Step S6, utilizes the Real-time Load I of current sensor measurement wire₀, utilize temperature sensor measurement wire real time environment temperature Spend T_a1And intensity of sunshine J_s, the wire heat transfer coefficient h (t) of current environmental condition is calculated, formula is as follows：

$h\left(t\right)=\frac{{I_0}^{2}R\left(T_{c1}\right)+Q_s-Q_r(T_{c1},T_{a1})}{T_{c1}-T_{a1}}$

In formula, I₀For wire Real-time Load electric current, T_c1、T_a1For wire real time temperature and environment real time temperature, R (T_c1) conductor temperature For T_c1When AC resistance, Q_r(T_c1,T_a1) it is heat loss through radiation power, Q_sFor sunshine Endothermic power；

Step S7, with wire maximum permissible temperature T_maxReplace wire real time temperature T_c1, calculate the maximum current-carrying of current state lower wire Measure I_max, formula is as follows：

$I_{\max }=\sqrt{\frac{h_{\max }\left(t\right)(T_{\max }-T_{a1})+Q_r(T_{\max },T_{a1})-Q_s}{R\left(T_{\max }\right)}}.$