CN103645408B - The method of discrimination of a kind of overhead transmission line short trouble and terminal - Google Patents

Abstract

The invention discloses method of discrimination and the terminal of a kind of overhead transmission line short trouble, wherein, the method includes: if the current virtual energy of overhead transmission line or the sudden change value of virtual power exceed threshold value, this sudden change value duration beyond time interval T and after described time interval T the voltage of current line and virtual energy or virtual power be zero, then judge that current line is short-circuited fault.By using method disclosed by the invention effectively, accurately short trouble is differentiated, thus security performance can be improve.

Description

The method of discrimination of a kind of overhead transmission line short trouble and terminal

Technical field

The present invention relates to distribution network system field, particularly relate to method of discrimination and the terminal of a kind of overhead transmission line short trouble.

Background technology

It is known that fuse can protect the circuit from short circuit, cross the infringement of stream.It rationale here is that short circuit Or when crossing stream, circuit instantaneous generation thermal energy suddenlys change, and melts the fuse that broken, thus loop of cutting off the electricity supply.

But, in prior art, the method for discrimination degree of accuracy for overhead transmission line short trouble is relatively low, it is impossible to carry out accurately The identification of short trouble；Accordingly, there exist bigger potential safety hazard.

Summary of the invention

It is an object of the invention to provide method of discrimination and the terminal of a kind of overhead transmission line short trouble, can effectively, the most right Short trouble differentiates, thus improves security performance.

It is an object of the invention to be achieved through the following technical solutions:

A kind of method of discrimination of overhead transmission line short trouble, the method includes:

If the current virtual energy of overhead transmission line or time the sudden change value of virtual power exceedes threshold value, this sudden change value duration exceeds Between be spaced T and after described time interval T the voltage of current line and virtual energy or virtual power be zero, then judge to work as Front circuit is short-circuited fault.

As seen from the above technical solution provided by the invention, sudden change value of based on virtual energy or power, this sudden change value Duration and postpone the numerical value of virtual energy or power after a period of time differentiate current overhead transmission line whether be short-circuited therefore Barrier；Its antijamming capability is relatively strong, and discriminant accuracy is higher.

Accompanying drawing explanation

In order to be illustrated more clearly that the technical scheme of the embodiment of the present invention, required use in embodiment being described below Accompanying drawing is briefly described, it should be apparent that, the accompanying drawing in describing below is only some embodiments of the present invention, for From the point of view of those of ordinary skill in the art, on the premise of not paying creative work, it is also possible to obtain according to these accompanying drawings Other accompanying drawings.

The schematic diagram of the method for discrimination of a kind of overhead transmission line short trouble that Fig. 1 provides for the embodiment of the present invention one；

The schematic diagram of a kind of overhead transmission line short trouble detection terminal that Fig. 2 provides for the embodiment of the present invention two.

Detailed description of the invention

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clearly and completely Describe, it is clear that described embodiment is only a part of embodiment of the present invention rather than whole embodiments.Based on Embodiments of the invention, it is every other that those of ordinary skill in the art are obtained under not making creative work premise Embodiment, broadly falls into protection scope of the present invention.

Embodiment one

It is illustrated in figure 1 the schematic diagram of the method for discrimination of a kind of overhead transmission line short trouble that the embodiment of the present invention provides.The party Method specifically includes that

If the current virtual energy of overhead transmission line or the sudden change value of virtual power exceedes threshold value, this sudden change value duration exceeds Time interval T and after described time interval T the voltage of current line and virtual energy or virtual power be zero, then judge Current line is short-circuited fault.

Above-mentioned threshold value and time interval T can according to the actual requirements or experience sets.

Instantaneous value computational methods below for virtual energy Yu virtual power do detailed introduction.

Energy transmission on power line comprises meritorious and idle two parts, and power component is consumed by resistor-type equipment, and Reactive component then for energy exchange, i.e. completes to be converted to magnetic energy by electric energy, then is converted to electric energy, Zhou Erfu by magnetic energy Begin, be transmitted to back and forth on power line, be not consumed.The embodiment of the present invention mainly considers the meter of power component energy Calculate.

If overhead transmission line is i (t) at the electric current of t, the equivalent resistance of overhead transmission line is R, then this overhead transmission line disappears in t The active power of consumption is:

P (t)=i²(t)R。

For the ease of calculating, it can be assumed that the equivalent resistance R=1 Ω of this circuit (does not the most consider the nothing that reactance and reactance produce Merit power), i.e. above formula can be exchanged into:

P (t)=i²(t)。

It practice, the R of circuit is not necessarily 1 Ω, simply found out the benchmark of a kind of comparison by this calculating, therefore, This power is virtual power.

A cycle (0, T can be calculated according to this virtual power₀In), the energy consumed:

$E\left(t\right)={\∫}_0^{T_0}P\left(t\right)\mathrm{dt};$

Wherein, t ∈ (0, T₀).Above-mentioned energy is to calculate based on virtual power to get, and is therefore virtual energy.Owing to p (t) is Change, thus the energy that different cycles calculates also is change.

When circuit is short-circuited, virtual energy can increase rapidly, produces sudden change.When Sudden Changing Rate increases to certain limit value, Circuit can be caused to trip, and causing line voltage distribution is 0 and follow-up measured nominal energy is 0.

The sudden change value of virtual energy can according to the virtual ENERGY E of t+ Δ t (the virtual ENERGY E (t) of t+ Δ t) and t calculates, Its formula is:

$\begin{array}{c}\mathrm{\ΔE}=E(t+\mathrm{\Δt})-E\left(t\right)\\ ={\∫}_0^{T_0}{i}^2(t+\mathrm{\Δt})\mathrm{dt}-{\∫}_0^{T_0}{i}^2\left(t\right)\mathrm{dt}\\ ={{\∫}_0^{T_0}(i\left(t\right)+\mathrm{\Δi})}^2\mathrm{dt}-{\∫}_0^{T_0}{i}^2\left(t\right)\mathrm{dt}\\ ={\∫}_0^{T_0}({\mathrm{\Δi}}^2+2i\left(t\right)\mathrm{\Δi})\mathrm{dt}\end{array};$

Wherein, Δ i represents that t is to the current variation value of t+ Δ t.

On the other hand, it is also possible to according to the mean power in one cycle of virtual energy balane, i.e. on the basis of virtual energy On divided by time T₀, it is expressed as:

$\stackrel{\‾}{p}=\frac{1}{T_0}{\∫}_0^{T_0}p\left(t\right)\mathrm{dt}=\frac{1}{T_0}{\∫}_0^{T_0}{i}^2\left(t\right)\mathrm{dt}.$

In like manner, the sudden change value of virtual power can also utilize sudden change value and the time T of virtual energy₀Calculate, its formula For:

$\mathrm{\Δ}\stackrel{\‾}{p}=\frac{\mathrm{\ΔE}}{T_0}=\frac{1}{T_0}{\∫}_0^{T_0}({\mathrm{\Δi}}^2+2i\left(t\right)\mathrm{\Δi})\mathrm{dt}.$

By the above formula, the degree of accuracy of current value will directly affect the accuracy differentiating result.The embodiment of the present invention can To use following method calculating current value: S cycle alternating voltage on the inductance that continuous sampling is connected with current line, by On inductance L, voltage waveform produces relatively big strange change, is not the most sinusoidal waveform；Therefore by the alternating voltage in described S cycle In the whole zero setting of negative half period alternating voltage, it is thus achieved that the positive half cycle alternating voltage of S；Calculate each positive half cycle maximum alternation Voltage, it is thus achieved that S maximum；After S maximum being sorted by size, take its median as once surveying 100A electric current school The reference data of quasi-value, it is thus achieved that with reference to coefficient；Remaining S-1 maximum is gone out corresponding with this reference coefficient scale factor calculation Current value.For meeting certainty of measurement and system operating rate, the sampling period can be set to 0.5ms.Wherein, for the ease of meter Above-mentioned S can be set to 5 by calculation.

This measured value method is summed up according to development Experience for many years and is formed, and has used for reference median filter method.The benefit of this method is filtering Effect is obvious, and amount of calculation is little, and speed is fast, and precision is high, can be controlled by current measurement value within positive and negative 3% precision, warp Within 2% error can being reached after overcurrent calibration.Significantly interference there are good anti-jamming effectiveness, relatively half-wave integration method Measured value precision improves a lot.

After embodiment of the present invention sudden change based on virtual energy or power value, the duration of this sudden change value and delay a period of time The numerical value of virtual energy or power differentiates whether current overhead transmission line is short-circuited fault；Its antijamming capability is relatively strong, and Discriminant accuracy is higher.

Embodiment two

The schematic diagram of a kind of overhead transmission line short trouble detection terminal that Fig. 2 provides for the embodiment of the present invention two.Such as Fig. 2 institute Showing, this terminal specifically includes that

The inductance L that is sequentially connected in series, the first resistance R1, analog/digital converter A/D, single-chip microcomputer, high-voltage measuring circuit and The second resistance R2, electric capacity C and the voltage-stabiliser tube D being connected in parallel between the first resistance R1 and A/D；

Wherein, described single-chip microcomputer, for calculating the sudden change value of virtual energy and virtual power value；

If the current virtual energy of overhead transmission line or time the sudden change value of virtual power exceedes threshold value, this sudden change value duration exceeds Between be spaced T and after described time interval T the voltage of current line and virtual energy or virtual power be zero, then judge to work as Front circuit is short-circuited fault.

Further, this terminal also includes:

The power supply being connected with described single-chip microcomputer and hardware watchdog.

In order to make it easy to understand, do detailed introduction below for its operation principle.

Trolley line alternating current produces alternating voltage to inductance L, avoids not allowing electricity to induce this voltage change the most as far as possible Sense L magnetic field is saturated, can arrange optimal wire circle by after test of many times；Meanwhile, use general iron core as sensing Bar magnet.Resistance R1 and R2 dividing potential drop, the upper voltage of R2 is as the input of analog quantity/digital quantity converter (A/D).In order to Avoiding the saturated input of A/D converter under the big function of current of trolley line, R1 and R2 resistance ratio can be by after test of many times It is set to optimal proportion.Voltage-stabiliser tube D and electric capacity C plays overvoltage protection and filtering interfering effect, it is to avoid A/D changes by shadow Ring.

Respective algorithms can be utilized to calculate by the current value of above circuit, recycling timer within single-chip microcomputer, The difference of two moment electric currents, i.e. Sudden Changing Rate can also be obtained.Such that it is able to calculate within the cycle of regulation, circuit is empty Intend changes delta E of energy.

High-voltage measuring circuit, is used for monitoring overhead transmission line high-voltage value, and high-voltage value by this circuit measuring out, is measured simultaneously Go out circuit high pressure with or without.

According to measured virtual energy and circuit high pressure with or without and the time of time delay, it is possible to accurately whether judge circuit Be short-circuited fault.

It addition, power supply can use power taking technology on high-voltage line to power to single-chip microcomputer, hardware watchdog main use prevents list Sheet machine be interfered after crash reset.

Wherein, current value Measurement Algorithm can use 5 half-wave maximum median methods.Concretely comprise the following steps: (1) continuous sampling Upper 5 the cycle alternating voltages of inductance L, owing on inductance L, voltage waveform produces relatively big strange change, are not the most sinusoidal waveforms.Will All whole zero setting of negative half period sampled point, only retain 5 positive half cycle sampled points.(2) obtain each positive half cycle maximum to adopt Sampling point.(3) 5 maximums of sequence.(4) the 3rd value reference data as once survey 100A correcting current value is taken, Other current value is obtained using this coefficient as scale factor.For meeting certainty of measurement and system operating rate, the sampling period is fixed For 0.5ms.

This measured value method is summed up according to development Experience for many years and is formed, and has used for reference median filter method.The benefit of this method is filtering Effect is obvious, and amount of calculation is little, and speed is fast, and precision is high, can be controlled by current measurement value within positive and negative 3% precision, warp Within 2% error can being reached after overcurrent calibration.Significantly interference there are good anti-jamming effectiveness, relatively half-wave integration method Measured value precision improves a lot.

It addition, concrete judgement and calculating process have been carried out detailed introduction in embodiment one, therefore repeat no more.

The above, the only present invention preferably detailed description of the invention, but protection scope of the present invention is not limited thereto, Any those familiar with the art in the technical scope of present disclosure, the change that can readily occur in or replace Change, all should contain within protection scope of the present invention.Therefore, protection scope of the present invention should be with claims Protection domain is as the criterion.

Claims (6)

1. the method for discrimination of an overhead transmission line short trouble, it is characterised in that the method includes:

If the current virtual energy of overhead transmission line or the sudden change value of virtual power exceedes threshold value, this sudden change value duration exceeds Time interval T and after described time interval T the voltage of current line and virtual energy or virtual power be zero, then judge Current line is short-circuited fault；Wherein:

When described virtual power is the equivalent resistance R=1 Ω assuming overhead transmission line, the wattful power that this overhead transmission line consumes in t Rate, its computing formula is:

P (t)=i²(t)；

Wherein, i represents the current value of t；

Virtual energy is for calculate a cycle (0, T according to virtual power₀The energy consumed in), its computing formula For:

$E\left(t\right)={\∫}_0^{T_0}P\left(t\right)dt;$

Wherein, t ∈ (0, T₀)。

Method the most according to claim 1, it is characterised in that the sudden change value method calculating virtual energy includes:

Utilize t+ Δ t virtual ENERGY E (the virtual ENERGY E (t) of t+ Δ t) and t calculates, and its formula is:

$\mathrm{\Δ}E=E(t+\mathrm{\Δ}t)-E\left(t\right)={\∫}_0^{T_0}({\mathrm{\Δi}}^2+2i(t\left)\mathrm{\Δ}i\right)dt;$

Wherein, Δ i represents that t is to the current variation value of t+ Δ t.

Method the most according to claim 2, it is characterised in that the sudden change value calculating method bag of described virtual power Include: utilize sudden change value and the time T of virtual energy₀Calculating, its formula is:

$\mathrm{\Δ}\stackrel{\‾}{p}=\frac{\mathrm{\Δ}E}{T_0}=\frac{1}{T_0}{\∫}_0^{T_0}({\mathrm{\Δi}}^2+2i(t\left)\mathrm{\Δ}i\right)dt.$

The most according to the method in claim 2 or 3, it is characterised in that the method also includes: the measurement step of current value And this step includes suddenly:

S cycle alternating voltage on the inductance that continuous sampling is connected with current line, and by the alternation electricity in described S cycle The whole zero setting of negative half period alternating voltage in pressure, it is thus achieved that S positive half cycle alternating voltage；

Calculate each positive half cycle maximum alternating voltage, it is thus achieved that S maximum；

Using the median in S maximum as the reference data once surveying 100A correcting current value, it is thus achieved that with reference to coefficient；

The current value that remaining S-1 maximum is corresponding is calculated with this reference coefficient.

5. overhead transmission line short trouble detection terminal, it is characterised in that this terminal includes: the inductance that is sequentially connected in series, First resistance, analog/digital converter, single-chip microcomputer, high-voltage measuring circuit and be connected in parallel on the first resistance and turn with analog/digital The second resistance, electric capacity and voltage-stabiliser tube between parallel operation；

Wherein, described single-chip microcomputer is for calculating the sudden change value of virtual energy and virtual power value；

If the current virtual energy of overhead transmission line or the sudden change value of virtual power exceedes threshold value, this sudden change value duration exceeds Time interval T and after described time interval T the voltage of current line and virtual energy or virtual power be zero, then judge Current line is short-circuited fault；

When described virtual power is the equivalent resistance R=1 Ω assuming overhead transmission line, the wattful power that this overhead transmission line consumes in t Rate, its computing formula is:

P (t)=i²(t)；

Wherein, i represents the current value of t；

Virtual energy is the cycle (0, T calculated according to virtual power₀The energy consumed in), its computing formula For:

$E\left(t\right)={\∫}_0^{T_0}P\left(t\right)dt;$

Wherein, t ∈ (0, T₀)。

Terminal the most according to claim 5, it is characterised in that this terminal also includes:

The power supply being connected with described single-chip microcomputer and hardware watchdog.