CN101494374A - Current protection control method for vacuum circuit breaker - Google Patents

Abstract

A current protection control method of a vacuum breaker includes the steps of: first sampling a current signal from a current transformer; then judging whether the sampled current signal is an overcurrent/short-circuit signal; if so, taking the sampled current signal as a parameter and calculating the current effective value; if the effective value is more than a setting value, conducting protection action; otherwise, continuing to sample. The steps for judging current signals are as follows: 2.1) first calculating the mutational volume iDelta-n of a group of sampling current signals of a plurality of continuous sampling points at intervals; if the mutational volume iDelta-n is more than a preset setting value iDelta-ns, entering into step 2.2); or if iDelta-n is no more than the preset setting value iDelta-ns, then continually calculating the mutational volume of current signals of next group of the sampling points, with the number of each group of sampling points being the same in the step; and 2.2) calculating the mutational volume iDeltak of each pair of adjacent sampling points in the group of sampling points, if each mutational volume iDeltak is more than the preset setting value iDelta1S, then judging the occurrence of overcurrent/short circuit, and entering step 3).

Description

Current protection control method in the vacuum circuit-breaker

Technical field

The invention belongs to the power transmission and transformation technical field, specifically is current protection control method in a kind of vacuum circuit-breaker that is applied in the power distribution network.

Background technology

Along with improving constantly of the development and national economy and the people's material and cultural life level, people are also increasing to the demand of electric power, thereby impel electric utility to develop rapidly, electrical network constantly enlarges, and the user is also more and more higher to the requirement of power supply quality and power supply reliability.Can distribution system safely, stable, operation reliably, not only is directly connected to the unobstructed of business electrical, and relate to electric power system and move normally.Therefore, when certain bar circuit was in the abnormal running state in the distribution network, line-breaker should be able to be in time, reliably with its excision, with trouble-proof further generation and expansion.In addition, when existing no-load transformer to close a floodgate in the circuit, can occur an instantaneity on the line and shove.Because it is not fault, line-breaker need not move, but its amplitude is very big, can cause the circuit situation unsuccessful or that higher level's line-breaker mistake is jumped of once closing a floodgate.Therefore, in actual motion, need line-breaker can cut off the circuit that is in overcurrent, short-circuit condition, can distinguish shoving of instantaneous appearance on overcurrent, short-circuit condition and the circuit of circuit again.

Existing application is less in the current protection control device of line-breaker; and conventional device has been taked based on the peak value of the electric current determination methods as setting value for the judgement of circuit overcurrent, short circuit, shoves and adds certain delay time when having taked line-breaker to close a floodgate suddenly and realize for escaping circuit.There are certain defective in overcurrent, the short-circuit condition of judging circuit like this, and higher level's line-breaker might miss jumping and fault distinguishing overlong time because of shoving when subordinate's circuit closes a floodgate suddenly.

In the prior art, self adaptation relaying protection algorithm can change in the protection sampling filter algorithm pairing data window shape according to the variation of power system operation mode and malfunction or window long.Because the adaptive guard algorithm can be adjusted data window according to the variation of the failure condition of primary system, therefore, it can overcome the defective of traditional protection to a great extent, effectively improves the corresponding speed of algorithm, shortens the fault distinguishing time.But the design of most of adaptive guard algorithms and research do not have too many change to the sampling filter algorithm, still use the adaptive algorithm that becomes data window substantially, and the step-length of algorithm and the rate of change of sudden change amount are not all done consideration.

Summary of the invention

In order to solve the above-mentioned problems in the prior art, the invention provides a kind of brand-new current protection control method that is suitable for vacuum circuit-breaker, on algorithm, all done brand-new design, concrete technical scheme is as follows:

Current protection control method in a kind of vacuum circuit-breaker comprises step:

1) from current transformer sample rate current signal;

2) sample in the primitive period at a current signal, judge that the current signal that sampling obtains is an interference signal, or overcurrent/short-circuit signal;

3) if overcurrent/short-circuit signal, then the current signal that obtains with sampling is a parameter, calculates current effective value, if this effective value, is then made the protection action greater than setting value; Otherwise, then continue sampling;

Described step 2) also comprise step in:

2.1) earlier to one group of sample rate current calculated signals sudden change amount i of a plurality of continuous sampled points at interval _Δ-nIf sudden change amount i _Δ-nGreater than its default setting value i _Δ-ns, then enter step 2.2); If i _Δ-nBe not more than default setting value i _Δ-ns, then continue the current signal of next group sampled point is calculated the sudden change amount; In this step, the number of every group of sampled point is identical;

2.2) every pair of adjacent sampled point in this group sampled point is calculated sudden change amount i _{Δ k}If, each sudden change amount i _{Δ k}All greater than its default setting value i _{Δ 1S}, then think overcurrent/short circuit, enter step 3).

In the step 1), when powering on suddenly, time-delay sampling, what occur when avoiding circuit at the corresponding levels and closing a floodgate suddenly shoves.

Step 2) in, 48 points of sampling in the primitive period, promptly sample frequency is 2400Hz.(existing fourier algorithm all is 12 points, also useful 24 points.Counting of sampling is many more, can react real situation more, but this will be subjected to the restriction of the sampling ability of equipment, can not make sample frequency excessive.Fourier algorithm of the prior art wants failure judgement must gather the data of a cycle, could judge that then judgement time is oversize.The present invention is one group of four point, as the foundation that judges whether to start the variable step algorithm, after the startup, according to the sudden change situation, determines that the function window is long, can shorten the differentiation time greatly like this.)

Step 2.1) in, described every group of current signal that the sample rate current signal is continuous 4 sampled points, described sudden change amount i _Δ-nBe the current value i (4m-1) of the 4th sampled point and the poor absolute value of current value i (4m-4) of the 1st sampled point.

Step 2.2) adjacent sampled point sudden change amount i in _{Δ k}It is respectively the absolute value of the electric current value difference of the 4th and 3 sampled point, the 3rd and 2 sampled point, the 2nd and 1 sampled point; If these three values are all greater than default setting value i _{Δ 1S}, then think overcurrent/short circuit, enter step 3).

In the step 3) according to step 2.2) in sudden change amount i _{Δ k}Rate of change di _{Δ k}=i _{Δ k}-i _{Δ k-1}Determine the long H=G (di of window in the fourier algorithm _{Δ k}), step delta k=Q (di _{Δ k}), wherein G, the Q prominent variable rate of serving as reasons is determined the long function of window and the step-length function of fourier algorithm sinusoidal windows; Then, the sinusoidal windows corresponding to the k time sampled value is $\mathrm{\ω}\left(h\right)=\frac{1}{H}\underset{h=k-H+1}{\overset{k}{\mathrm{\Σ}}}{a}_h\sin \frac{2\mathrm{\πh}}{K};$

So, the amplitude of the fundametal compoment cosine amount of determining by fourier algorithm $a_1=\frac{1}{H}\left[2\underset{h=k-H+1}{\overset{k}{\mathrm{\Σ}}}i\left(h\right)\cos \frac{2(h+\mathrm{\Δk})\mathrm{\π}}{K}\right]$ Amplitude with the fundametal compoment sinusoidal quantity $b_{}$ ${}_1=\frac{1}{H}\left[2\underset{h=k-H+1}{\overset{k}{\mathrm{\Σ}}}i\left(h\right)\sin \frac{2(h+\mathrm{\Δk})\mathrm{\π}}{K}\right],$ Wherein K is the sampling number in the first-harmonic one-period, and h is a sampling number in the window; The sample rate current value that i (h) is ordered for h;

At last, obtain the effective value of electric current $I_{}$ ${}_1=\sqrt{\frac{a_1^2+{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="A20091002567600141.png,A20091002567600142.png"\; state="\{\{state\}\}">b</figure-callout>}}_1^2}{2}},$ If effective value, is then made the protection action greater than its setting value.

Setting value in the described step 3) determines that by the electric current of minitype CT secondary side the setting value scope is at 5A-30A.

i _Δ-nsThe value principle: 48 points of one-period sampling are the 360/12=30 degree with regard to the angle of being separated by between per 4 points.Sine or cosine function be the derivative maximum in the time of zero crossing; that is to say at that time the difference maximum between two points; so maximum difference is sin30-sin0=0.5; multiply by the rated maximum current of protection circuit with this coefficient; get final product multiply by a corresponding coefficient; this coefficient that multiply by at last can be fitted sensitivity and be required to adjust voluntarily, generally gets 1.2.～1.5A.

i _{Δ 1S}The value principle: 48 points of one-period sampling are the 360/48=7.5 degree with regard to the angle of being separated by between each point.Sine or cosine function be the derivative maximum in the time of zero crossing; that is to say at that time the difference maximum between two points; so maximum difference is sin7.5-sin0=0.1305; multiply by the rated maximum current of protection circuit with this coefficient; get final product multiply by a corresponding coefficient; this coefficient that multiply by at last can be fitted sensitivity and be required to adjust voluntarily, generally gets 1.2.～1.5A.

The present invention has fault current is quick on the draw, accuracy of judgement, the advantage that judgement time is short.

Description of drawings

Fig. 1 is the adaptive filtration theory block diagram

The circuit theory diagrams of Fig. 2 for installing among the embodiment

Fig. 3 is power circuit principle figure in the device

Fig. 4 is a reset circuit schematic diagram in the device

Fig. 5 is that A in the device, C biphase current are gathered measuring principle figure

Fig. 6 is single-chip microcomputer and a LCD liquid crystal display connection layout in the device

Fig. 7 is switching value output, LED displaying principle figure in the device

Fig. 8 is a tripping coil drive circuit schematic diagram in the device

Fig. 9 is a real-time clock module schematic diagram in the device

Figure 10 is a Single Chip Microcomputer (SCM) program flow chart in the device

Embodiment

The invention will be further described below in conjunction with accompanying drawing and embodiment.

At first the algorithm that the present invention is adopted is described in detail.

In the prior art, the research of adaptive-filtering starts from the fifties in last century.With reference to figure 1, the iterative formula of adaptive-filtering is

c(k)＝d(k)-y(k)＝X ^T(k)W ^*(k)-X ^T(k)W(k)……(1)

e(k)＝y(k)-y′(k)＝d(k)+ξ(k)-y′(k)＝c(k)+ξ(k)……(2)

W(k+1)＝W(k)+2μe(k)X(k)……(3)

In the formula, X ^T(k) be n reference-input signal constantly; W (k) is the weight coefficient of sef-adapting filter; W ^*(k) be the unknown system weight coefficient; D (k) is a desired signal; Y ' is a filter output signal (k); E (k) is the error signal of being made up of ξ (k) and c (k); ξ (k) is an interference signal, and c (k) is a tracking error signal; μ is a step factor.

The purpose of adaptive algorithm is exactly to approach W by the weights W (k) that Error Feedback is constantly adjusted filter ^*(k), make y ' (k) can follow the tracks of the variation of d (k).

In the relaying protection algorithm, the current signal of establishing input is i (t), and Fu Shi after decomposing is

In the formula, f _nBe the nth harmonic frequency, I _nBe the amplitude of harmonic wave,

Phase angle for harmonic wave.i ₁(t) be fundamental current, i _h(t) be all harmonic current summations except that fundamental current.With i _h(t) be made as interference signal ξ (k) among Fig. 1, i ₁(t) as desired signal d (k), input current signal i (t) conduct is with reference to input signal X (k).The relaying protection algorithm is not further limited at this for existing mature technology.

In the Microcomputer Protection algorithm, input current signal i (t) is after reference-input signal X (k) enters sef-adapting filter, and output signal y ' (k) follows the tracks of desired signal d (k), and y ' (k) approaches current first harmonics component i from amplitude and phase place ₁(t).When y ' (k) when amplitude and phase place all equate, promptly the decidable malfunction enters exception handles.The Microcomputer Protection algorithm is not further limited at this for existing mature technology.

Traditional adaptive filter algorithm is generally the fixed step size adaptive algorithm; promptly do not consider step factor μ; mainly be to change response speed and the computational accuracy of protecting algorithm, and W (k) often consider also can't change in hardware program once determining by changing weight coefficient W (k).Therefore, traditional adaptive guard algorithm can't be taken into account between response speed and computational accuracy.

In the prior art, for the current signal that is sampled in the formula (4)

After being launched into fourier series be $i\left(t\right)=\underset{n=0}{\overset{\&infin;}{\mathrm{\&Sigma;}}}[a_n\sin \left(n{\mathrm{\&omega;}}_{1}t\right)+b_n\cos \left(n{\mathrm{\&omega;}}_{1}t\right)],$ In the formula, n is a natural number; ω ₁Expression first-harmonic angular frequency; a _nAnd b _nRepresent the cosine term of each harmonic and the amplitude of sine term, wherein a respectively ₀The expression DC component.

With a ₁And b ₁The amplitude of representing fundametal compoment cosine amount, sinusoidal quantity respectively, then, the first-harmonic effective value is: ${\mathrm{<figure-callout\; id="1"\; label="I"\; filenames="A20091002567600141.png,A20091002567600142.png"\; state="\{\{state\}\}">I</figure-callout>}}_1=\sqrt{\frac{a_1^2+{\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="A20091002567600141.png,A20091002567600142.png"\; state="\{\{state\}\}">b</figure-callout>}}_1^2}{2}}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(5\right)$

Consider the long H=hT of being of window _WDuring=T, a ₁And b ₁For:

$\begin{array}{c}{a}_1=\frac{1}{T}{\&Integral;}_t^{t+T}i\left(\mathrm{\&tau;}\right)\cos \left(\mathrm{\&omega;\&tau;}\right)\mathrm{d\&tau;}=\frac{1}{h{T}_W}{\&Integral;}_t^{t+h{T}_W}i\left(\mathrm{\&tau;}\right)\cos \left(\mathrm{\&omega;\&tau;}\right)\mathrm{d\&tau;}\\ b_1=\frac{1}{T}{\&Integral;}_t^{t+T}i\left(\mathrm{\&tau;}\right)\sin \left(\mathrm{\&omega;\&tau;}\right)\mathrm{d\&tau;}=\frac{1}{h{T}_W}{\&Integral;}_t^{t+{\mathrm{hT}}_W}i\left(\mathrm{\&tau;}\right)\sin \left(\mathrm{\&omega;\&tau;}\right)\mathrm{d\&tau;}\end{array},$ T in the formula _WBe the time in sampling interval, h is the sampling number in the sample window, ω=2 π f, and f is a fundamental frequency, T=1/f.

After the sampling, continuous function becomes discrete function, and integral operation becomes discrete summation operation.

The sinusoidal windows of discrete full-wave fourier algorithm can be expressed as: $\mathrm{\&omega;}\left(k\right)=\frac{1}{K}\underset{k=0}{\overset{K-1}{\mathrm{\&Sigma;}}}{a}_{\mathrm{<figure-callout\; id="2"\; label="k\; sin"\; filenames="A20091002567600141.png,A20091002567600153.png"\; state="\{\{state\}\}">k</figure-callout>}}\sin \frac{2\mathrm{\&pi;k}}{K},$ K is the sampling number in the first-harmonic one-period in the formula, k=0, and 1,2 ..., K-1.Preferred K=48 in this example, promptly sample frequency is 2400Hz.

The variable-step self-adaptive algorithm of the embodiment of the invention is under the operational mode that does not detect sudden change amount (per 4 sampled points calculate once sudden change amount), get last in per four sampled points, it is k '=4m-1 (m=0,1,2, ..., 12) calculate participation Fu Shi and calculate, calculate the input current effective value, be equivalent to per sampling period 12 sampled points for fourier algorithm this moment, promptly the phase sampled point is K '=12 weekly

This moment a ₁And b ₁For $\begin{array}{c}{a}_1=\frac{1}{K^{\&prime;}}\left[2\underset{k^{\&prime;}=0}{\overset{K^{\&prime;}-1}{\mathrm{\&Sigma;}}}i\left(k^{\&prime;}\right)\cos \frac{2k^{\&prime;}\mathrm{\&pi;}}{K^{\&prime;}}\right]\\ {\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="A20091002567600141.png,A20091002567600142.png"\; state="\{\{state\}\}">b</figure-callout>}}_1=\frac{1}{K^{\&prime;}}\left[2\underset{k^{\&prime;}=0}{\overset{K^{\&prime;}-1}{\mathrm{\&Sigma;}}}i\left(k^{\&prime;}\right)\sin \frac{2k^{\&prime;}\mathrm{\&pi;}}{K^{\&prime;}}\right]\end{array}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(6\right),$ I in the formula (k ') is the inferior rice of the k ' of a current signal sample value.

In like manner, the sampling interval of calculating the sudden change amount also is 4 sampled points, after k '=4m-1 sampling finishes, with instantaneous value i (the 4m-1)=i (k ') of this time sampling and the instantaneous value i (4 (m-1)-1) of k '=4 (m-1)-1 time sampling=i (k '-1) calculating sudden change amount: i _Δ-4=|| i (k ') |-| i (k '-1) || ... (7)

As sudden change amount i _Δ-4Greater than its setting value i _Δ-4SThe time, start variable step sudden change amount and calculate.Calculating the k=4m-1 time sampled value reaches with first three constantly: three sudden change amounts of the sampled value of k-1=4m-2, k-2=4m-3, k-3=4m-4:

i _Δk＝||i(4m-1)|-|i(4m-2)||＝||i(k)|-|i(k-1)||、

i _Δk-1＝||i(4m-2)|-|i(4m-3)||＝||i(k-1)|-|i(k-2)||、

i _Δk-2＝||i(4m-3)|-|i(4m-4)||＝||i(k-2)|-|i(k-3)||……(8)

With three i _{Δ k}, i _{Δ k-1}, i _{Δ k-2}With setting value i _{Δ 1S}Relatively, when three sudden change amounts all greater than setting value i _{Δ 1S}The time, it is long to start adaptive windows.

If not all greater than setting value, then continue sampling and calculate the sudden change amount, calculate the adjacent sampled point of sampling of sudden change amount, i.e. i this moment _{Δ k}=|| i (k) |-| i (k-1) || ... (9), like this, with improving the speed that the sudden change amount detects greatly, in the variation of the relevant input variable of the fastest time internal reaction primary system.

When three continuous sudden change amount i occurring _{Δ 1}During greater than setting value, the rate of change of establishing the sudden change amount is:

di _Δk＝i _Δk-i _Δk-1……(11)

Determine the long H=G (di of being of window of fourier algorithm according to the rate of change of sudden change amount _{Δ k}) ... (12), the algorithm step-length of Que Dinging is Δ k=Q (di _{Δ k}) ... (13), G, the Q prominent variable rate of serving as reasons is determined the long function of window and the step-length function of fourier algorithm sinusoidal windows:

H _FullBe that the full-wave fourier algorithm window is long, promptly data window comprises the whole sampled points in the cycle.

After determining the long H of window, see that corresponding to the sinusoidal windows of k sampled value is $\mathrm{\&omega;}\left(h\right)=\frac{1}{H}\underset{h=k-H+1}{\overset{k}{\mathrm{\&Sigma;}}}{a}_{\mathrm{<figure-callout\; id="2"\; label="h\; sin"\; filenames="A20091002567600141.png,A20091002567600153.png"\; state="\{\{state\}\}">h</figure-callout>}}\sin \frac{2\mathrm{\&pi;h}}{K}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(14\right);$

By the definite a of fourier algorithm ₁And b ₁For: $\begin{array}{c}{a}_1=\frac{1}{H}\left[2\underset{h=k-H+1}{\overset{k}{\mathrm{\&Sigma;}}}i\left(h\right)\cos \frac{2(h+\mathrm{\&Delta;k})\mathrm{\&pi;}}{K}\right]\\ {\mathrm{<figure-callout\; id="1"\; label="b"\; filenames="A20091002567600141.png,A20091002567600142.png"\; state="\{\{state\}\}">b</figure-callout>}}_1=\frac{1}{H}\left[2\underset{h=k-H+1}{\overset{k}{\mathrm{\&Sigma;}}}i\left(h\right)\sin \frac{2(h+\mathrm{\&Delta;k})\mathrm{\&pi;}}{K}\right]\end{array}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(15\right)$

According to formula (5), each sampling finishes to calculate the effective value of current first harmonics, again with setting value I _1-DZRelatively, when the first-harmonic effective value that calculates greater than setting value I _1-DZThen send the protection actuating signal.

The implement device of said method is the current protection control device, this device comprises power module, single-chip microcomputer, A, C phase current mutual inductor, electric quantity signal collecting module, human-computer interaction interface module, switching value output module and tripping coil driver module, with host computer communication module, clock module; The output of described power module connects the power input of single-chip microcomputer; The output of A, C phase current mutual inductor connects the input of electric quantity signal collecting module respectively, and the output of signal acquisition module connects the acquired signal input of single-chip microcomputer after the A/D conversion; The parameter input is connected the input of single-chip microcomputer with display module; Single-chip microcomputer is expanded 485 serial line interfaces and is realized communicating by letter with host computer, utilizes single-chip microcomputer I ²C interface connects clock reality module; The output of single-chip microcomputer connects the input of switching value output module, and the output of switching value output module connects the control end of tripping coil driver module, and the power end of tripping coil driver module is connected to the output of A, C instrument transformer; The output of tripping coil driver module connects outside tripping coil.

Described electric quantity signal collecting module comprises two current transformer CT1, CT2, their input connects the output of A, C phase current mutual inductor respectively, and the output signal of two current transformers is imported the acquired signal input of single-chip microcomputer respectively again into through the A/D conversion after adjustable resistance, the conditioning of group capacitor filter circuit.Described A, C phase current mutual inductor output current in current transformer CT1 and CT2 sampling back and the output that is connected to the input that is connected micro-transformer of current CT3 together, current transformer CT3 connect input through power module.Described tripping coil driver module comprises booster circuit, storage capacitor and rectifier bridge, and booster circuit and energy storage capacitor in series are the storage capacitor charging; Storage capacitor is with rectifier bridge and be linked together the tripping coil that is connected the control device outside, and the control tripping coil is threaded off.

The host computer communication that is set forth in adopts 485 serial communication interface technology to finish and the communicating by letter of host computer, and parameter setting also can be undertaken by host computer.

Described time clock feature realizes by external DS1307 clock chip.

Described human-computer interaction interface cooperates liquid crystal reality to finish the setting of various parameters by function button, and LCD can also be used to the kind of real fault, the size of fault current, fault time, information such as stoppage circuit breaker numbering.These two functions are integrated on the piece circuit board, can be connected with main circuit board by connector, realize the on-site parameters setting, also can be installed on the controlling platform, carry out remote parameter by universal serial bus and set.

Described single-chip microcomputer is the M16C/62P series monolithic M30626FHPFP that Japanese Rui Sa company releases, and external frequency is the 10MHz crystal oscillator; The RESET input of single-chip microcomputer connects reset circuit; Also external clock reality chip; 485 buses have been expanded; The output of single-chip microcomputer also connects the display module that LCD forms.

Shown in Fig. 3,4, power module suppresses circuit, common mode and differential mode inhibition circuit by current transformer, full-wave rectifying circuit, voltage stabilizing circuit, transient overvoltage and forms.Circuit A, C biphase current instrument transformer output current are in micro-transformer of current sampling back and be connected to together, through inner another micro-transformer of current of controller, full-wave rectifying circuit, voltage stabilizing circuit, make alternating voltage become the little 12V direct voltage of fluctuation, promptly can be the relay power supply.Start-up circuit, serial regulating circuit, protective circuit are contained in integrated voltage stabilizing chip 7805 inside, + 12V direct voltage is become stable+5V voltage, be the power supply of devices such as amplifier, voltage stabilizing didoe Z1 with the overvoltage Limiting of circuit at certain level, protection relay coil and back level 7805 devices such as grade; Capacitor C 2 can suppress the noise that produces because of load variations, plays a part a low frequency disturbance filter.Again+5V direct voltage being become stable+3.3V voltage, is the power supply of controller inside single-chip microcomputer, and output connects 10uF electric capacity and guarantees the stability exported, and as shown in Figure 3, the voltage checking chip of Cai Yonging is the MAX708RD of PHILIPS Co. here.MAX708RD is the voltage monitoring chip of a being used for+3.3V power-supply system, and the threshold voltage that resets is+2.63V to have double loop power supply monitoring, power-fail alarm and reset function and hand-reset function.When reset button SW1 closure, system just powered on or the supply voltage of MAX708RD drop to+2.63V is once the time, low active homing output pin step-down, chip M16C/62P-M30626FHPFP reliable reset.

As shown in Figure 3, electric quantity signal collecting module is divided into A, C two phase acquisitions, and each is by a current transformer, one road adjustable resistance, rc filter circuit, and amplifier is formed, and inserts the single-chip processor i/o pin respectively.

As shown in Figure 4, LCD and single-chip microcomputer connection layout.With the corresponding data wire of LCD with control line connects and M16C/62P-M30626FHPFP, LCD is carried out corresponding write operation just can realize that LCD shows.

As shown in Figure 5, the switching value output module is made up of relay, optocoupler TLP521, driving triode and protective circuit, and the single-chip microcomputer output pin is defeated to be connected relay two ends parallel connected in reverse phase fast diode IN4148 with the control utmost point of triode.

As shown in Figure 6, the tripping coil driver module is made up of booster circuit, storage capacitor, rectifier bridge, connects the tripping coil of control device outside as output port

As shown in Figure 7, be real time clock circuit.Controller need be to the accurate record of time, with convenient maintenance and fault statistics to the protection of short trouble.Therefore single-chip microcomputer timer internal limited amount needs special hardware real-time clock.For this reason, controller has been chosen the I that U.S. DALLAS company releases ²C bus interface real-time timepiece chip DS1307 ^]Button cell with+3V.

Program circuit as shown in Figure 8, concrete steps are:

(1) initialization;

(2) combined floodgate time-delay (adjustable);

(3) gather A, C biphase current and judge whether current effective value surpasses setting value;

(4) not, then resampling returns step 3; Be then the phase current that surpasses setting value to be become step adaptive discrete Fourier branch.If ratio surpasses the threshold value of magnetizing inrush current, then thinking has the unexpected idle-loaded switching-on of transformer in the circuit, does not have overcurrent, short trouble, also returns step 3.If ratio does not surpass the threshold value of magnetizing inrush current, then in the delay time that is provided with by the switching value input, judge whether circuit exists overcurrent, short-circuit condition continuously; If not overcurrent, the short circuit of continuation, return step 3, if the overcurrent of continuation, short circuit, then control circuit breaker open operation.

(5) finish.

The internal structure of device and outside connected mode are as shown in figure 10.Device has 5 outside leads, and wherein 3 connect A, C phase current mutual inductor, and the common port of current transformer connects casing, inserts the earth; Other 2 connect tripping coil, the control breaker open operation.In the frame of broken lines is the internal structure of device, and connected mode is that lead connects.Be that 485 serial communications leave binding post, can whether go between according to the applicable cases decision.

By adjusting, setting value can be adjusted into 5A to adjustable resistance B, C.Control method is as follows: will install with the A phase current mutual inductor and connect, and the instrument transformer output current is adjusted into 5A, and regulate adjustable resistance B against the direction of arrow among the figure then.When LED lamp D becomes even flicker by not working, A phase setting value is that adjusted is 5A.C phase setting value method of adjustment is with the method for adjustment of A phase.When connecting human-computer interaction interface, LCD is last can reality to adjust the result.

After the setting value adjustment finishes, carry out the setting of guard time.Go up menu by LCD and cooperate function key, set corresponding quick-break multiple, the quick-break time, and the inrush phenomenon time-delay is provided with.

After above-mentioned steps all finishes, will install and connect with line-breaker and fixing.Line 1～3 connects current transformer among Fig. 3, and 4～5 connect tripping coil.When line-breaker powered on suddenly, device started the internal delay time program, escaped shoving of this moment; After circuit stable operation, if occur shoving, device can identify it according to algorithm, can not make the circuit breaker misoperation; Only be under overcurrent, the short-circuit condition at circuit, device is just controlled its switching value output circuit, makes it connect the tripping coil drive circuit.Tripping coil get electric after, impact the snap close link of breaker operation mechanism, remove its deadlock state, breaker open operation.

At last, by 485 serial line interfaces, with the host computer that passes to of fault message practical work.

Structurally, device adopts inserter structure, independent closed cell cabinet, and good airproof performance, anti-interference, firm reliable, the anti-vibration ability is strong.

Described device adopts the high-performance single-chip microcomputer, and this single-chip microcomputer is stable, and antijamming capability is strong.Can directly apply to the line-breaker of only installing A, C biphase current instrument transformer,, escape the current protection control device that shoves as cutting off overcurrent, short circuit line.Its power supply is directly taken from the line current instrument transformer, does not need extra equipment such as voltage transformer.

Aspect the guard time cooperation, its overcurrent delay time can be set arbitrarily, and quick-break electric current multiple can be set arbitrarily, and the quick-break delay time can be set arbitrarily, and the combined floodgate delay time can be set arbitrarily, can fully satisfy the needs of various actual motions.

Aspect the separating brake control of line-breaker, what its tripping coil drive circuit adopted is the mode that charging capacitor and line current provide electric current simultaneously; Because charging capacitor has been arranged, the power requirement of current transformer is little on the circuit, and 5VA gets final product, like this size of current transformer can do smaller, precision also can improve, and makes its easier installation and use.

The online identification aspect of passing by stream, short circuit and shoving, it adopts by calculating current effective value and starts the fault distinguishing program, comes identification circuit overcurrent, short-circuit condition and shoves based on the magnetizing inrush current identification new method of variable-step self-adaptive algorithm.Promptly add time-delay when powering on suddenly at device, what occur when avoiding circuit at the corresponding levels and closing a floodgate suddenly shoves; After stable operation, calculate current effective value,, change step-length if surpass set point and reach criterion by variable step; call adaptive algorithm; come identification circuit overcurrent, short circuit or shove,, and circuit at the corresponding levels is implemented protection with shoving of avoiding that subordinate's circuit occurs.This algorithm can improve the response speed of Microcomputer Protection effectively, improves the Microcomputer Protection performance.

Time that can the Statement of Facts fault, upload fault message to host computer.485 buses of expansion can external GPRS module, realizes that the real-time radio of data transmits, and satisfies the requirement of distribution automation.

The good man-machine interaction interface.The human-computer interaction interface module adopts interface to be connected with main circuit, can in time plug as required, also human-computer interaction interface can be installed on the control protection platform, carries out remote control.

Claims (6)

1, current protection control method in a kind of vacuum circuit-breaker comprises step:

1) from current transformer sample rate current signal;

2) sample in the primitive period at a current signal, judge that the current signal that sampling obtains is an interference signal, or overcurrent/short-circuit signal;

3) if overcurrent/short-circuit signal, then the current signal that obtains with sampling is a parameter, calculates current effective value, if this effective value, is then made the protection action greater than setting value; Otherwise, then continue sampling;

It is characterized in that described step 2) in also comprise step:

2.1) earlier to one group of sample rate current calculated signals sudden change amount i of a plurality of continuous sampled points at interval _Δ-nIf sudden change amount i _Δ-nGreater than its default setting value i _Δ-ns, then enter step 2.2); If i _Δ-nBe not more than default setting value i _Δ-ns, then continue the current signal of next group sampled point is calculated the sudden change amount; In this step, the number of every group of sampled point is identical;

2.2) every pair of adjacent sampled point in this group sampled point is calculated sudden change amount i _{Δ k}If, each sudden change amount i _{Δ k}All greater than its default setting value i _{Δ 1S}, then think overcurrent/short circuit, enter step 3).

2, current protection control method in the vacuum circuit-breaker according to claim 1 is characterized in that in the step 1), when powering on suddenly, and time-delay sampling, what occur when avoiding circuit at the corresponding levels and closing a floodgate suddenly shoves.

3, current protection control method in the vacuum circuit-breaker according to claim 1 is characterized in that step 2) in, 48 points of sampling in the primitive period, promptly sample frequency is 2400Hz.

4, current protection control method in the vacuum circuit-breaker according to claim 3, feature is a step 2.1) in, described every group of current signal that the sample rate current signal is continuous 4 sampled points, described sudden change amount i _Δ-nBe the current value i (4m-1) of the 4th sampled point and the poor absolute value of current value i (4m-4) of the 1st sampled point.

5, current protection control method in the vacuum circuit-breaker according to claim 4 is characterized in that step 2.2) in adjacent sampled point sudden change amount i _{Δ k}It is respectively the absolute value of the electric current value difference of the 4th and 3 sampled point, the 3rd and 2 sampled point, the 2nd and 1 sampled point; If these three values are all greater than default setting value i _{Δ 1S}, then think overcurrent/short circuit, enter step 3);

If each sudden change amount i _{Δ k}Not all greater than its default setting value i _{Δ 1S}, then think not to be overcurrent/short circuit, continue sampling.

6, current protection control method in the vacuum circuit-breaker according to claim 5 is characterized in that in the described step 3) according to step 2.2) in sudden change amount i _{Δ k}Rate of change di _{Δ k}=i _{Δ k}-i _{Δ k-1}Determine the long H=G (di of window in the fourier algorithm _{Δ k}), step delta k=Q (di _{Δ k}), wherein G, the Q prominent variable rate of serving as reasons is determined the long function of window and the step-length function of fourier algorithm sinusoidal windows:

Be that the full-wave fourier algorithm window is long, promptly data window comprises the whole sampled points in the cycle; Then, the sinusoidal windows corresponding to the k time sampled value is $\mathrm{\&omega;}\left(h\right)=\frac{1}{H}\underset{h=k-H+1}{\overset{k}{\mathrm{\&Sigma;}}}{a}_h\sin \frac{2\mathrm{\&pi;h}}{K};$

So, the amplitude of the fundametal compoment cosine amount of determining by fourier algorithm $a_1=\frac{1}{H}\left[2\underset{h=k-H+1}{\overset{k}{\mathrm{\&Sigma;}}}i\left(h\right)\cos \frac{2(h+\mathrm{\&Delta;k})\mathrm{\&pi;}}{K}\right]$ Amplitude with the fundametal compoment sinusoidal quantity $b_1=\frac{1}{H}\left[2\underset{h=k-H+1}{\overset{k}{\mathrm{\&Sigma;}}}i\left(h\right)\sin \frac{2(h+\mathrm{\&Delta;k})\mathrm{\&pi;}}{K}\right],$ Wherein K is the sampling number in the first-harmonic one-period, and h is a sampling number in the window; The sample rate current value that i (h) is ordered for h;

At last, obtain the effective value of electric current $I_1=\sqrt{\frac{a_1^2+b_1^2}{2}},$ If effective value, is then made the protection action greater than its setting value.

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