Summary of the invention:
The objective of the invention is to provide a kind of method of eliminating dead band, high-voltage fence single-ended traveling wave fault location, colliery, solve existing single-ended traveling wave fault location because the fault traveling wave feature is difficult to differentiate, abort situation and if circuit essential characteristic when coupling, the problem of judging the dead band deficiency is arranged especially.
The object of the present invention is achieved like this: this method is passed through the calculated value of line topological parameter known structure and the comparison of measured value, get rid of the wave head of non-fault line reflection, reflection wave wave head and the trouble spot reflection wave wave head of trouble-shooting circuit opposite end bus are special wave head; Further to special wave head classified calculating, eliminate the dead band, location, the realization fault is accurately located;
A, definition line ripple instantaneous power:
The characteristic spectra of row ripple is f=10~100kHz, namely in above-mentioned frequency range, and the energy maximum of row ripple; Travelling wave signal is before CT or PT introducing data collector, signal is carried out bandpass filtering treatment, suppress the very high frequency(VHF) signal in the electric system, avoid the superposition of travelling wave signal on power frequency and harmonic wave thereof, dwindle the dynamic fluctuation scope of signal, improve the resolution of data acquisition;
Because after fault took place, the lead with distribution parameter had formed wave process, electromagnetic field is to propagate to the circuit two ends near the light velocity, and the energy of electromagnetic field of definition line ripple is instantaneous power, and its catastrophe point is defined as capable ripple due in equally; Voltage signal u (t) in the certain hour section that observation station is obtained, current signal i (t) after the Clark conversion, obtains line mold component u
α(t) and i
α(t), and definition line ripple instantaneous power, p (t)=u
α(t) i
α(t);
B, special wave head confirms mutually:
Under the known situation of circuit topological parameter, according to row wave-wave speed theoretical value, calculate the row ripple in advance and travel to and fro between the used time of fault measuring point and each outlet end or take-off point, be designated as t '
i, wherein, when i represented that circuit normally moves, from measurement point, the number of wave impedance point of discontinuity comprised take-off point and line end point; Observe the d1 layer of row ripple instantaneous power signal after the db6 wavelet decomposition, record row ripple arrives the moment t of measurement point for the first time
0, calculate respectively and can observe wave head and initial wave head mistiming t constantly
m-t
0, wherein, m represents that reality can be observed the number of wave head, comprises take-off point except initial row wave-wave head, the reflection wave of line end point and trouble spot;
Contrast calculated value and measured value are got rid of the wave head that non-fault line reflects, and reflection wave wave head and the trouble spot reflection wave wave head of trouble-shooting circuit opposite end bus are special wave head;
There are following three kinds of situations in special wave head:
1, two wave heads all can't be corresponding with theoretical value, and the opposite end bus reflection wave of fault outlet at this moment and trouble spot reflection wave are all not overlapping with other wave heads;
2, there are a wave head and the theoretical value can't be corresponding, at this moment produced the dead-time problem of single-ended traveling wave distance-finding method, this is divided into again: the reflection wave of trouble spot overlaps with the reflection wave of certain bar outlet, and the opposite end bus reflection wave of fault outlet overlaps with the reflection wave of certain bar outlet;
3, trouble spot reflection wave and opposite end bus reflection wave are all overlapping with the reflection wave of non-fault line, i.e. the extreme case in single-ended traveling wave range finding dead band.
The present invention has defined capable ripple instantaneous power, p (t)=u
α(t) i
α(t), because the method for single analytical voltage or current signal is subject to interference of noise in the electrical network, be prone to the erroneous judgement of wave head, and row ripple instantaneous power has effectively been improved the adaptability of wave head identification to noise.
Beneficial effect, because in service in actual electric network, travelling wave signal is vulnerable to interference of noise, during the discrimination of wavelet analysis modulus maximum, the less capable ripple catastrophe point of amplitude inevitably can cause the erroneous judgement of row wave-wave head, makes a big impact for the result of localization of fault.Utilize the capable ripple instantaneous power of row wave voltage, electric current definition, amplified the sudden change amplitude of signal at a certain catastrophe point place, reduced the amplitude of noise from another point of view, effectively strengthened in the capable ripple than the resolution degree of smooth sea head, made the more feasible and precision of localization method.
The situation in the range finding dead band on the principle that occurs at the single-ended traveling wave localization method, according to the special wave heads of two reaction fault distances, i.e. the mathematical relation of trouble spot reflection wave and faulty line opposite end bus reflection wave, v (Δ T
1+ Δ T
2)=2L, wherein, Δ T
1Be the mistiming of trouble spot reflection wave with initial wave head, Δ T
2Be the mistiming of opposite end bus reflection wave with initial wave head, v is the velocity of propagation of row ripple in certain medium, and L is the total length of faulty line.To each capable ripple identification one by one that observes, get rid of the reflection wave wave head of non-fault line and take-off point, utilize the arbitrary due in the above-mentioned special wave head, carry out localization of fault.This method is used the mathematical relation of two wave heads and is verified, has effectively improved adaptability and the feasibility of single-ended traveling wave distance-finding method, has reached purpose of the present invention.
The present invention compared with prior art has following advantage:
1, defines capable ripple instantaneous power, improved the capable wave-wave head resolution degree under the strong noise in actual electric network;
2, in the electrical network of colliery, utilize two methods that special wave head is verified mutually of fault outlet, solved in the cable joint line, velocity of wave is inconsistent, the impalpable problem of wave head;
Embodiment
Embodiment 1: this method is got rid of the wave head of non-fault line reflection by to the calculated value of line topological parameter known structure and the comparison of measured value, and reflection wave wave head and the trouble spot reflection wave wave head of trouble-shooting circuit opposite end bus are special wave head; Further to special wave head classified calculating, eliminate the dead band, location, the realization fault is accurately located;
1, definition line ripple instantaneous power:
The characteristic spectra of row ripple is f=10~100kHz, namely in above-mentioned frequency range, and the energy maximum of row ripple.Travelling wave signal is before CT or PT introducing data collector, need carry out bandpass filtering treatment to signal, purpose is the very high frequency(VHF) signal that suppresses in the electric system, and avoids the superposition of travelling wave signal on power frequency and harmonic wave thereof, dwindle the dynamic fluctuation scope of signal, improve the resolution of data acquisition;
Because after fault took place, the lead with distribution parameter had formed wave process, electromagnetic field is propagated to the circuit two ends with certain speed, and energy of electromagnetic field that can the definition line ripple is instantaneous power, and its catastrophe point may be defined as capable ripple due in equally; Voltage signal u (t) in the certain hour section that observation station is obtained, current signal i (t) after the Clark conversion, obtains line mold component u
α(t) and i
α(t), and definition line ripple instantaneous power, p (t)=u
α(t) i
α(t).
2, the special wave head method of confirming mutually:
Under the known situation of circuit topological parameter, according to row wave-wave speed theoretical value, calculate the row ripple in advance and travel to and fro between the used time of fault measuring point and each outlet end or take-off point, be designated as t '
i, wherein, when i represented that circuit normally moves, from measurement point, the number of wave impedance point of discontinuity comprised take-off point and line end point; Observe the d1 layer of row ripple instantaneous power signal after the db6 wavelet decomposition, record row ripple arrives the moment t of measurement point for the first time
0, calculate respectively and can observe wave head and initial wave head mistiming t constantly
m-t
0, wherein, m represents that reality can be observed the number of wave head, comprises take-off point except initial row wave-wave head, the reflection wave of line end point and trouble spot;
Contrast calculated value and measured value are got rid of the wave head that non-fault line reflects, and reflection wave wave head and the trouble spot reflection wave wave head of trouble-shooting circuit opposite end bus are special wave head.There are following three kinds of situations in special wave head:
1, if there are two wave heads can't be corresponding with theoretical value, illustrates that these two wave heads are respectively fault point reflection ripple and opposite end bus reflection wave;
2, if only have the wave head can't be corresponding with theoretical value, the dead band that method of single end distance measurement occurred be described, namely trouble spot reflection wave or faulty line opposite end bus reflect wave head and overlap with non-fault line fault reflection wave wave head; Utilize the relation of the mistiming of two wave heads that react the faulty line total length, that is: v (Δ T
1+ Δ T
2)=2L, wherein, Δ T
1Be the mistiming of trouble spot reflection wave with initial wave head, Δ T
2Be the mistiming of opposite end bus reflection wave with initial wave head, v is the velocity of propagation of row ripple in certain medium, and L is the total length of faulty line.Calculated value calculates opposite end bus reflection wave or the trouble spot reflection wave wave head of this wave head correspondence, if can determine then that with a certain theoretical constantly corresponding this reflection wave head is from opposite end bus or trouble spot;
3, if wave head is all corresponding with theoretical value, illustrate that the opposite end bus reflection wave of fault outlet and trouble spot reflection wave are all overlapping with non-fault outlet wave head, this is a kind of opposite extreme situations; In time period T, respectively each wave head is carried out as 2) calculating checking, distinguish wave head with this.
Adopt corresponding method to calculate fault distance at above different situation.
This method specific implementation process flow diagram as shown in Figure 1, the concrete steps of this method are as follows:
When 1, break down in the cable outlet somewhere of system, utilize high-speed data acquisition card to adopt 10MHz or higher sampling rate to obtain electric current and the voltage signal of CT, PT secondary side, respectively it is carried out Clark conversion decoupling zero, and calculate the capable ripple instantaneous power of line mould correspondence;
2, under the known situation of circuit topological parameter, according to row wave-wave speed theoretical value, calculate the row ripple in advance and travel to and fro between the used time of fault measuring point and each outlet end or take-off point, be designated as t '
i, wherein, when i represented that circuit normally moves, from measurement point, the number of wave impedance point of discontinuity comprised take-off point and line end point.
3, observe the d1 layer of row ripple instantaneous power signal after the db6 wavelet decomposition, record row ripple arrives the moment t of measurement point for the first time
0, calculate respectively and can observe wave head and initial wave head mistiming t constantly
m-t
0, wherein, m represents that reality can be observed the number of wave head, comprises take-off point except initial row wave-wave head, the reflection wave of line end point and trouble spot.
4, with 3) and 2) contrast, get rid of the wave head that non-fault line reflects, if two wave heads can't be corresponding with theoretical value, opposite end bus reflection wave and all not outlet and other wave head overlappings of trouble spot reflection wave of fault outlet are described then, can directly calculate fault distance; If only have a wave head corresponding with theoretical value, then above-mentioned two wave head one and other wave head taken place overlapping, i.e. the dead-time problem of single-ended traveling wave distance-finding method.
5, the problems referred to above solution is divided into two kinds of situations again: the reflection wave of trouble spot overlaps with the wave head of the reflection wave of certain bar outlet, the wave head that has only opposite end bus reflection wave that can find this moment, utilize the relation of trouble spot reflection wave and opposite end bus reflection wave wave head due in to verify, determine fault distance with this; The reflection wave of the opposite end bus of fault outlet overlaps with the wave head of the reflection wave of certain bar outlet, and localization method and the previous case are similar.
6, if trouble spot reflection wave and opposite end bus reflection wave all with the reflection wave overlapping of non-fault line, it is the extreme case in single-ended traveling wave range finding dead band, then calculate the due in of its corresponding special wave head according to the outer wave head of initial wave head one by one, overlap the capable wave-wave head that is reflection faulty line length that occurs constantly at wave head.
Embodiment 2: the present invention has very high position precision and possesses very high adaptability at complicated power distribution network, and system or the system scale of different scales change, and the present invention all can satisfy.Be example with a model now:
In Fig. 2, overhead transmission line and cable adopt Frequency Dependent (Phase) Model, and this model more can reflect transient state and the harmonic characteristic of circuit.Wherein, the 10kV network has 6 outlets, 3 overhead transmission lines, 2 cable lines, 1 cable joint line (adding thick line is cable).The parameter of overhead transmission line is: zero sequence impedance 0.3E-03+j0.1E-02 Ω/m, positive sequence impedance 0.3E-04+j0.4E-03 Ω/m; The zero sequence admittance is 0.1E-10+j0.2E-08S/m, and the positive sequence admittance is 0.1E-10+j0.3E-08S/m.The parameter of cable is: zero sequence impedance is 0.2E-03+j0.2E-02 Ω/m, and the impedance of positive sequence is 0.3E-04+j0.2E-03 Ω/m; The zero sequence admittance is j0.2E-07S/m, and the positive sequence admittance is j0.2E-07S/m.Can calculate the α mould velocity of wave of overhead transmission line, v according to line parameter circuit value
α 1=2.994E8m/s, cable line v
α 2=1.5169E8m/s.The transformer that outlet termination Y-Δ type connects, no-load voltage ratio is 35/11kV, capacity is 31.5MVA, the transformer that load side joint Y-Δ type connects, no-load voltage ratio is 10/0.66kV, and capacity is 1MVA, and neutral point adopts earth-free mode.Fixed load model is used in load, and is set to inductive load.Because the cable fault that occurs in the electrical network of colliery mostly be singlephase earth fault, and stake resistance is little under most of situation, so, emulation with A through 100 Ohmage ground connection.
Situation for single-line to ground fault, must use phase-model transformation that each lead is carried out decoupling zero, thereby determine single velocity of wave, actual distribution line transposition is also insufficient, but when using balanced circuit modular transformation matrix that asymmetric circuit is carried out decoupling zero, coupling between each modulus is very little, handles so can be reduced to balanced circuit, uses real number matrix Clark conversion.And the α mold component is fed the Butterworth bandpass filter of 10~100kHz second order.Become common one-end fault positioning principle to carry out.Fault took place in time period of back 0.1ms, and the detected transient voltage in bus place, electric current be the transient state waveform of α mould and calculated as shown in Figure 3 by voltage, galvanometer after the Clark conversion respectively, has become common one-end fault positioning principle to carry out.
In Fig. 3, comparison with voltage, current signal, the waveform of row ripple instantaneous power is level and smooth relatively, and the amplitude of ripple is littler, though signal is after filtering, the amplitude of noise can reduce to some extent, but because data acquisition, factors such as filtering link still can't avoid noise to the influence of weak travelling wave signal, especially in the electrical network of the colliery of reality, the capable ripple instantaneous power of this paper definition can effectively reduce and influenced by outside noise.
Note t
0Be initial wave head due in, according to the line length parameter and in conjunction with the route selection result, can calculate the mistiming of reflection wave due in the initial wave head of certain bar outlet correspondence, that is to say, after fault traveling wave arrives measurement point (bus), time period of return measurement point again through other paths, be designated as t respectively
1,, t
11, the result is as shown in table 1 below.
Table 1 calculates the theoretical value of the corresponding reflection of each outlet wave head due in according to line parameter circuit value
Wherein, outlet NO. delegation represents i bar outlet end reflection ripple and arrives measurement point constantly, i
mBe illustrated in the reflection wave due in that outlet comes and goes m time, 4 ' representing the 4th outlet cable to blend the moment that reflection wave arrives measuring junction, i-j represents that the row ripple reflects not only moment of entering j bar outlet reflected back measuring junction or row ripple enter i bar outlet reflected back measuring junction through the outlet of j bar but also refraction the moment through the outlet of i bar.The db6 wavelet analysis is carried out in utilization above defined small echo instantaneous power, and wherein, the analysis result of d1 layer as shown in Figure 4.
In Fig. 4, if in fault the unknown, under the fault moment condition of unknown, utilize that initial wave head due in reads t among the figure respectively as benchmark among Fig. 4
1~t
11Relative t
0Coordinate constantly, and with table 1 in the time contrast of reaction non-fault line total length or other impedance point of discontinuity.
The result of contrast shows among 11 related wave heads, t is only arranged
5-t
0The theoretical value of the wave head time difference that=49.94us can't calculate with table 1 is close, and under normal circumstances, because the effect of dispersion of row ripple, in observing the finite time section of wave head, should also have two wave heads obviously to observe at least obtains, be the primary reflection of trouble spot and the primary reflection of faulty line load side, but among Fig. 4, but only observed an identification wave head.Clearly, because the complicacy of colliery power distribution network circuit and the randomness of fault distance, there is the possibility in dead band, location in the single-ended traveling wave range finding, be that fault distance equates just with certain bar outlet, cause row wave-wave head to arrive simultaneously, the wave head of reaction fault distance is overlapping with the wave head of reaction non-fault line total length.
At this moment, this paper proposes to utilize the reflection wave of the trouble spot that one-end fault ranging derives and the relation of opposite end bus reflection wave wave head time of arrival namely: v (Δ T
1+ Δ T
2)=2L determines that special wave head eliminates the influence in dead band, wherein, and Δ T
1Be the mistiming of trouble spot reflection wave with initial wave head, Δ T
2Be the mistiming of opposite end bus reflection wave with initial wave head, v is the velocity of propagation of row ripple in certain medium, and L is the total length of faulty line, and x is the distance that check point is arrived in the trouble spot.If t
5-t
0=49.94us is the mistiming of trouble spot reflection wave due in and initial wave head, and then Dui Ying opposite end bus reflection wave due in is (t
5-t
0The 42.19us of) '=; If t
5-t
0=49.94us is the mistiming of opposite end bus reflection wave and initial wave head, and then Dui Ying trouble spot reflection wave due in is (t
5-t
0The 28.9us of) '=.From table 1, we can see that 42.19us is between t
3With t
4Between, and 28.9us and t
2Very approaching, then can determine t
5-t
0=49.94us is the mistiming of opposite end bus reflection wave and initial wave head, and namely can calculate fault distance is 2.192km, and absolute error is 8m.