CN104319905A - Quick self-healing system of power distribution network - Google Patents

Abstract

The invention provides a quick self-healing system of a power distribution network. The quick self-healing system comprises data transmission units DTU of all distribution substations arranged in the power distribution network. All the data transmission units DTU are connected together through an optical fiber network. The data transmission units DTU are used for conducting sampling on four associated branch circuits according to a scheduled time interval, synchronizing collected current data, judging a fault point according to the synchronized current data and controlling switch-on and switch-off devices of the distribution substations to remove or isolate the fault point. Since the quick self-healing system does not need to rely on a main station system, the problems existing in information acquisition and channel blockage will not occur; accordingly, the fault point of the power distribution network can be positioned and removed quickly.

Description

A kind of rapidly self-healing system of distribution network

Technical field

The application relates to technical field of electric power, more particularly, relates to a kind of rapidly self-healing system of distribution network.

Background technology

In recent years; along with the construction of national intelligent power network; more and more higher to the requirement of power supply quality and reliability; and urban distribution network circuit is generally less than 1 ~ 10kM at present; circuit is shorter, and during line failure, the fault current of each segmentation is close to identical; traditional stage overcurrent protection is difficult to distinguish on current ration, the time limit is difficult to coordinate.And existing power distribution network Monitoring and Controlling and data acquisition system (SCADA) rely on main station system due to needs; also the problem of information gathering and channel block can be there is; thus easily cause overstep tripping and isolated fault and recover the prolongation of fault time; this just needs a kind of protection system that can make distribution network rapidly self-healing badly, to enable distribution network quick position, excision fault point.

Summary of the invention

In view of this, the application provides a kind of rapidly self-healing system of distribution network, for the fault point of quick position excision distribution network.

To achieve these goals, the existing scheme proposed is as follows:

A rapidly self-healing system for distribution network, comprises multiple data transmission unit and fiber optic network, wherein:

Described fiber optic network is used for described multiple data transmission unit to link together;

Described multiple data transmission unit is separately positioned in multiple distribution substations of described distribution network, for the carrying out interval sampling on schedule according to four branch roads to association, then carry out synchronously to the current data collected, judge fault point according to the described current data after synchronous, and described fault point is excised by the opening and closing device controlling described distribution substation.

Preferably, described distribution network is 1 ~ 10kV distribution network.

Preferably, described fiber optic network is synchronous serial interface E1 dedicated fibre optical network.

Preferably, two described data transmission units are undertaken synchronously by the described current data of 4 branch roads before and after the realization of vector compensation technology.

Preferably, described data transmission unit comprises 4 differential protection logic elements, for sampling to the electric current of 4 branch roads respectively.

Preferably, also comprise 4 current transformers, described 4 differential protection logical blocks utilize the electric current of 1 described current transformer to 1 branch road to sample respectively.

Preferably, described data transmission unit utilizes vertical connection split-phase type current differential protection principle to protect described distribution network.

Preferably; described data set forth the time difference discrimination principles that unit adopts the vertical Sudden Changing Rate of connection split-phase type differential current and the Sudden Changing Rate of stalling current; realize described CT saturation status monitoring and blocking function, cause described distribution substation to occur false protection to prevent external area error.

Preferably, by the change of monitoring positive sequence voltage, described data transmission unit judges whether described branch road is weak feedback side.

Preferably, when judging that described branch road is as weak feedback rear flank, is changed into the mains side of described data transmission unit.

As can be seen from technique scheme, this application provides a kind of distribution network rapidly self-healing system, this rapidly self-healing system comprises the data transmission unit DTU being separately positioned on each distribution substation in distribution network, then light network is utilized to be linked together by all data transmission unit DTU, this data transmission unit DTU is used for separately interval on schedule by carrying out synchronized sampling to four branch roads, then carry out synchronously to the current data collected, fault point is judged again according to the current data after synchronous, and this fault point carries out excising or isolating by the opening and closing device controlling distribution substation.Because this rapidly self-healing system is without the need to relying on main station system, thus the problem of information gathering and channel block can not be there is, therefore, it is possible to the fault point of quick position excision distribution network.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present application or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the application, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.

The structure chart of the rapidly self-healing system of a kind of distribution network that Fig. 1 provides for the embodiment of the present application;

The active region schematic diagram of a kind of vertical split-phase type differential current that Fig. 2 provides for the application;

The one vertical connection split-phase type differential current logic diagram that Fig. 3 provides for the application;

The one vertical connection split-phase type differential current integral system figure that Fig. 4 provides for the application;

The one weak feedback enable logic schematic diagram that Fig. 5 provides for the application.

Embodiment

Below in conjunction with the accompanying drawing in the embodiment of the present application, be clearly and completely described the technical scheme in the embodiment of the present application, obviously, described embodiment is only some embodiments of the present application, instead of whole embodiments.Based on the embodiment in the application, those of ordinary skill in the art are not making the every other embodiment obtained under creative work prerequisite, all belong to the scope of the application's protection.

The structure chart of the rapidly self-healing system of a kind of distribution network that Fig. 1 provides for the embodiment of the present application.

As shown in Figure 1, the rapidly self-healing system of the distribution network that the present embodiment provides comprises multiple data transmission unit DTU and fiber optic network 100, and this rapidly self-healing system is applicable to 1 ~ 10kV distribution network.

Data transmission unit DTU is arranged in the distribution substation of distribution network, and the plurality of data transmission unit DTU links together by fiber optic network 100.Fiber optic network 100 is preferably synchronous passes mouth E1 fiber optic network.

Data transmission unit DTU be used for according to respective clock on schedule the electric current of interval to 4 of distribution substation branch roads sample.Then before and after being realized by vector compensation technology, the current data of 4 branch roads is carried out synchronously, and judge fault point according to the current data after synchronous, this fault point is isolated or excises by the opening and closing device then controlling distribution substation.

As can be seen from technique scheme, present embodiments provide a kind of distribution network rapidly self-healing system, this rapidly self-healing system comprises the data transmission unit DTU being separately positioned on each distribution substation in distribution network, then light network is utilized to be linked together by all data transmission unit DTU, this data transmission unit DTU is used for separately interval on schedule by carrying out synchronized sampling to four branch roads, then carry out synchronously to the current data collected, fault point is judged again according to the current data after synchronous, and this fault point carries out excising or isolating by the opening and closing device controlling distribution substation.Because this rapidly self-healing system is without the need to relying on main station system, thus the problem of information gathering and channel block can not be there is, therefore, it is possible to the fault point of quick position excision distribution network.

The application utilizes the principle of vertical connection split-phase type current differential protection, is multiplexed with the optical cable component wire that power distribution automation lays, does not increase passage cost, reach the object of complete fibre.And vertical connection split-phase type current differential protection adopts the data synchronization technology based on fault phasor; when this side calculate sampling delay error be greater than 0.05ms (electrical degree 0.9 °) time; with this moment for benchmark; stamp time tag; calculate fault current phasor; then utilize the synchronous serial communication technology based on optical fiber to transmit this phasor to opposite end, judge whether to belong to troubles inside the sample space by vertical split-phase type current differential protection, thus produce relevant protection act behavior.Synchronous serial passage itself carries channel data synchronous task, and analog quantity sampled data conveyer belt reference time label, just can conveniently calculate and monitor the change of channel delay, and carries out real-time phasor compensation to the change of communication channel delay.

Simultaneously; the application also adopts the time difference discrimination principles of split-phase type differential current Sudden Changing Rate and stalling current Sudden Changing Rate; prevent distribution line external area error from causing instrument transformer saturated and make the situation of differential protection malfunction; weak feedback side fault initiating is judged by the change of monitoring positive sequence voltage; whether adaptive determination apparatus is in weak feedback side, can available protecting light current source and non-transformer side device.

Vertical connection split-phase type current differential protection is: under proper communication condition, receive the differential permission signal of offside; this side difference of phase currents or this side line road are in one of weak feedback state and satisfy condition; though when this side without TA broken string or have TA break configure not Blocking Differential Protection condition meet; under vertical split-phase type current differential protection configuration input condition; in any one differential current computing cycle, if differential current and stalling current meet following relation:

(1)I _cd>I _czd

(2)I _z≤I _zzd1

Or I _zzd1<I _z≤ I _zzd2i _cd>I _czd+ K _z1(I _z-I _zzd1)

Or I _z>I _zzd2i _cd>=I _czd+ K _z1(I _zzd2-I _zzd1)+K _z2(I _z-I _zzd2)

Wherein I _cdfor differential current, I _zfor stalling current, K _z1for the section of MN shown in Fig. 2 ratio brake coefficient, K _z2for NQ section ratio brake coefficient.

At this moment, immediately vertical phase-comparison protection element is started mark and be transmitted to offside, continuous three differential current computing cycles all meet operation condition, send vertical connection phase-comparison protection action command and " action of vertical connection phase-comparison protection " SOE information immediately.

As Fig. 4; in the DTU of distribution substation 2; be integrated with 4 differential protection logic elements of former and later two direction branch roads 201,202,203 and 204; achieve the differential protection function of 4 branch roads and the synchronous acquisition of electric current; information is intercoursed between adjacent DTU; can realize the synchronous data sampling of former and later two distribution substations and this distribution substation totally 8 current signals, logic function integrated level is high.Wherein QF11, QF12, QF13, QF14, QF21, QF22, QF23, QF24, QF31, QF32, QF33, QF34 are the circuit breaker of circuit shown in Fig. 1, and CT11, CT12, CT13, CT14, CT21, CT22, CT23, CT24, CT31, CT32, CT33, CT34 are respectively the current transformer be connected with each circuit breaker.

The present invention adopts DTU realizing vertical connection split-phase type current differential protection between feeder line between two; the method of data synchronization adopted carries out between two; in DTU, the communication channel delay of same physical channel is identical; compensation of delay algorithm and parameter are also identical; common-use tunnel time delay can monitor element, a DTU has 2 to such data syn-chronization algorithm, for convenience of description; only for one of them branch road, the method for data synchronization principle that the phasor of communication channel delay compensates is described.

DTU two ends are carried out each phase current by respective sample frequency (on schedule interval) and are sampled simultaneously, all each electric current is carried out to the Fourier transform of first-harmonic after each sampling completes, obtain with sampled point one to one with the electric current phasor that real part and imaginary part represent.Under normal condition, this DTU constantly calculates the time difference Tm=T2-T1 of the information of receiving and the information of transmission, it to be sent to the DTU of offside with the information that next time sends as the parameter of sampling delay monitoring, DTU by current Tm compared with the Tm0 remembered during previous correction error, if when the absolute value of both differences is greater than 0.05ms (electrical degree 0.9 °), start sampling error calculation command immediately, send sampling error and calculate startup message.

This side DTU sends message in the T0 moment, offside DTU receives this message in the T1 moment, by the time T2 of next timed sending moment, calculate Tm=T2-T1, by T2, Tm, T0 temporal information sends to this DTU, this side DTU receives message in the T3 moment, so just obtain at designated lane, based on this DTU clock time T0 under fixed route condition, T3 and based on the T2 of offside DTU clock and the communication channel delay of time difference Tm: TR=TS=(T3-T0-Tm)/2, sampling delay error is: △ T=T3-TR-T4=0.5* (T3+T0+Tm)-T4, T4 is before this side DTU receives offside DTU sampling error correction startup message, the moment of the last transmission message.△ T>0 illustrates that offside DTU lags behind this DTU sampling, and △ T<0 illustrates that offside DTU is ahead of this DTU sampling.

This DTU preserves after calculating sampling delay error and passes to offside DTU immediately, be initial number 1 by self analog quantity markers numbering involution simultaneously, after offside DTU receives the sampling delay error time that this DTU sends, represent that sampling delay error calculation terminates, also be initial number 1 by the involution of analog quantity markers, the electric current phasor with identical numbering compares by both sides, and carries out phasor compensation with the θ angle that △ T is corresponding.

The electric current phasor real part making this DTU receive offside DTU is x, and imaginary part is y, and the corresponding θ angle of sampling delay error, θ=2 π f △ T, f is current electric grid frequency.

During △ T>0, offside DTU sampling lag △ T, offside DTU sampled phasor should carry out positive θ angle compensation could carry out differential calculating with the sampled data of this DTU, and the compensation formula of this DTU is: x '=xcos θ-ysin θ y '=ycos θ+xsin θ; The θ angle compensation that this DTU sampled phasor should carry out bearing could carry out differential calculating with the sampled data of offside DTU, and the compensation formula of offside DTU is: x '=xcos θ+ysin θ y '=ycos θ-xsin θ.

During △ T<0, offside DTU samples an advanced △ T, the θ angle compensation that offside DTU sampled phasor should carry out bearing could carry out differential calculating with the sampled data of this DTU, and the compensation formula of this DTU is: x '=xcos θ+ysin θ y '=ycos θ-xsin θ; This DTU sampled phasor should carry out positive θ angle compensation could carry out differential calculating with the sampled data of offside DTU, and the compensation formula of offside DTU side is: x '=xcos θ-ysin θ y '=ycos θ+xsin θ.

The application adopts the time difference discrimination principles of split-phase type differential current Sudden Changing Rate and stalling current Sudden Changing Rate, monitoring current instrument transformer saturation condition, and when distribution line external area error occurring and causing instrument transformer saturated, protection blocking, prevents differential protection malfunction.

Entry condition (current-difference sudden-change component startup) is met in protection, if differential current power frequency variation criterion delayed stalling current power frequency variation criterion is greater than 8 sampling intervals (i.e. 1/4 power frequency period, 32 points are gathered) by every power frequency period, namely think that TA is saturated, phase-comparison protection 160 sampling interval duration (5 cycles) of locking both sides immediately, phase current second harmonic as each in both sides and triple-frequency harmonics sum and the ratio of this phase fundamental current are all less than setting value (giving tacit consent to 15%) open differential protection again, otherwise differential protection locking is always until ratio differential condition returns.

The differential current being data window terminal with a kth sampled point calculates:

be respectively certain the phase current phasor after calculating with the kth sampled point Fourier that is data window terminal.

The differential current being data window terminal with kth-N number of sampled point calculates:

$I_{\mathrm{cd\&phi;}(k-N)}=|{\stackrel{\&CenterDot;}{I}}_{1\mathrm{\&phi;}(k-N)}+{\stackrel{\&CenterDot;}{I}}_{2\mathrm{\&phi;}(k-N)}|$

Calculate with the differential current that kth-2N sampled point is data window terminal:

$I_{\mathrm{cd\&phi;}(k-2N)}=|{\stackrel{\&CenterDot;}{I}}_{1\mathrm{\&phi;}(k-2N)}+{\stackrel{\&CenterDot;}{I}}_{2\mathrm{\&phi;}(k-2N)}|$

Differential current power frequency changes. amount: $\mathrm{\&Delta;}{I}_{\mathrm{cd\&phi;}\left(k\right)}=|{\stackrel{\&CenterDot;}{I}}_{\mathrm{cd\&phi;}\left(k\right)}-2{\stackrel{\&CenterDot;}{I}}_{\mathrm{cd\&phi;}(k-N)}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{cd\&phi;}(k-2N)}|$

The saturated criterion of differential current power frequency variation: Δ I _{cd φ (k)}>=1.25 Δ I _cdN+ I _qD

${\mathrm{\&Delta;I}}_{\mathrm{cdN}}=\mathrm{MAX}[{\mathrm{\&Delta;i}}_{\mathrm{cdA}}^{(k-N)},\mathrm{\&Delta;}{i}_{\mathrm{cdB}}^{(k-N)},\mathrm{\&Delta;}{i}_{\mathrm{cdC}}^{(k-N)}]$

I _qDgenerally adjust by 0.2 times of secondary rated current.

The stalling current being data window terminal with a kth sampled point calculates:

be respectively certain the phase current phasor after calculating with the kth sampled point Fourier that is data window terminal.

The stalling current being data window terminal with kth-N number of sampled point calculates:

$I_{\mathrm{zd\&phi;}(k-N)}=|{\stackrel{\&CenterDot;}{I}}_{1\mathrm{\&phi;}(k-N)}-{\stackrel{\&CenterDot;}{I}}_{2\mathrm{\&phi;}(k-N)}|$

Calculate with the stalling current that kth-2N sampled point is data window terminal:

$I_{\mathrm{zd\&phi;}(k-2N)}=|{\stackrel{\&CenterDot;}{I}}_{1\mathrm{\&phi;}(k-2N)}-{\stackrel{\&CenterDot;}{I}}_{2\mathrm{\&phi;}(k-2N)}|$

Stalling current power frequency variation: $\mathrm{\&Delta;}{I}_{\mathrm{zd\&phi;}\left(k\right)}=|{\stackrel{\&CenterDot;}{I}}_{\mathrm{zd\&phi;}\left(k\right)}-2{\stackrel{\&CenterDot;}{I}}_{\mathrm{zd\&phi;}(k-N)}+{\stackrel{\&CenterDot;}{I}}_{\mathrm{zd\&phi;}(k-2N)}|$

The saturated criterion of stalling current power frequency variation: Δ I _{zd φ (k)}>=1.25 Δ I _zdN+ I _qD

${\mathrm{\&Delta;I}}_{\mathrm{zdN}}=\mathrm{MAX}[{\mathrm{\&Delta;i}}_{\mathrm{zdA}}^{(k-N)},\mathrm{\&Delta;}{i}_{\mathrm{zdB}}^{(k-N)},\mathrm{\&Delta;}{i}_{\mathrm{zdC}}^{(k-N)}]$

I _qDgenerally adjust by 0.2 times of secondary rated current.

The application judges weak feedback side fault initiating principle by the change of monitoring positive sequence voltage, and whether adaptive determination apparatus is in weak feedback side.As shown in Figure 5; difference of phase currents, overcurrent all do not start; if bus positive sequence voltage becomes positive sequence phase voltage from normal value (positive sequence phase voltage is greater than 50V) be less than 30V; or bus positive sequence line voltage becomes positive sequence line voltage from normal value (positive sequence line voltage is greater than 90V) and is less than 50V; doublely meet this condition above-mentioned, just put weak feedback and start mark, protection does not meet operation condition 200ms and returns; protection meets operation condition, returns after trip signal sends.The present invention effectively can meet the running environment that distribution line each side operational mode changes often, if operational mode changes (running as this side changes mains side into), without manual amendment's definite value, weak feedback entry condition automatically exits and can effectively satisfy condition.

In this specification, each embodiment adopts the mode of going forward one by one to describe, and what each embodiment stressed is the difference with other embodiments, between each embodiment identical similar portion mutually see.To the above-mentioned explanation of the disclosed embodiments, professional and technical personnel in the field are realized or uses the application.To be apparent for those skilled in the art to the multiple amendment of these embodiments, General Principle as defined herein when not departing from the spirit or scope of the application, can realize in other embodiments.Therefore, the application can not be restricted to these embodiments shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.

Claims (10)

1. a rapidly self-healing system for distribution network, is characterized in that, comprises multiple data transmission unit and fiber optic network, wherein:

Described fiber optic network is used for described multiple data transmission unit to link together;

Described multiple data transmission unit is separately positioned in multiple distribution substations of described distribution network, for sampling to the current synchronization of 4 branch roads at interval on schedule according to each self-clock, then carry out synchronously to the current data collected, judge fault point according to the described current data after synchronous, and described fault point is excised by the opening and closing device controlling described distribution substation.

2. rapidly self-healing system as claimed in claim 1, it is characterized in that, described distribution network is 1 ~ 10kV distribution network.

3. rapidly self-healing system as claimed in claim 1, it is characterized in that, described fiber optic network is synchronous serial interface E1 dedicated fibre optical network.

4. rapidly self-healing system as claimed in claim 1, is characterized in that, before and after two described data transmission units are realized by vector compensation technology, the described current data of 4 branch roads is carried out synchronously.

5. rapidly self-healing system as claimed in claim 1, it is characterized in that, described data transmission unit comprises 4 differential protection logic elements, for realizing by phase differential protection the electric current of 4 branch roads respectively.

6. rapidly self-healing system as claimed in claim 5, it is characterized in that, also comprise 4 current transformers, described 4 differential protection logical blocks utilize the electric current of 1 described current transformer to 1 branch road to sample respectively.

7. rapidly self-healing system as claimed in claim 1, is characterized in that, described data transmission unit utilizes vertical connection split-phase type current differential protection principle to protect described distribution network.

8. the rapidly self-healing system as described in any one of claim 1 ~ 7; it is characterized in that; described data set forth the time difference discrimination principles that unit adopts the Sudden Changing Rate of split-phase type differential current and the Sudden Changing Rate of stalling current; realize described CT saturation status monitoring and blocking function, cause described distribution substation to occur false protection to prevent external area error.

9. rapidly self-healing system as claimed in claim 8, is characterized in that, by the change of monitoring positive sequence voltage, described data transmission unit judges whether described branch road is weak feedback side.

10. rapidly self-healing system as claimed in claim 9, is characterized in that, when judging that described branch road is as weak feedback rear flank, is changed into the mains side of described data transmission unit.