CN101877676B - Method for judging change of differential protection route according to change of unidirectional transmission delay - Google Patents

Abstract

The invention relates to a method for judging change of a differential protection route according to change of unidirectional transmission delay. The time delay of protective devices at the two ends of a circuit is calculated to obtain unidirectional time delay so as to judge the change of a transceiving route; and a triggering device performs resampling and synchronization adjustment. Through the method, the change of a bidirectional route is judged by only partially modifying software without adding hardware equipment, so that the harsh requirement of a differential protective device on the consistency of bidirectional time delay is met and differential protection has wider application.

Description

The method judging differential protection route changing is changed by unidirectional transmission time delay

Technical field

The invention belongs to field of power, be specifically related to a kind of circuit longitudinal differential protection based on data channel synchronization method according to the change of propagation delay time, judge the method for two-way route changing.

Background technology

(1) method of testing of unidirectional transmission time delay

On-scene communication circuit unidirectional transmission time delay all adopts loopback test, namely at test far-end, hoop is back to near-end, and instrument sends signal through circuit loopback, and draw two-way time delay according to the transmission of instrument and receive clock, the half of test result is One Way Delay.

Can respectively configure an accurate clock source in circuit two ends at the scene in theory, two clock sources require Complete Synchronization, and one end is to the message of the free label of opposite end transmit band, and the difference of the time and opposite end time that receive message is One Way Delay by opposite end.The method possible in theory, but testing cost is expensive, and impracticable.

The method of testing of therefore, really less accurately, practical, feasible on-the-spot unidirectional transmission time delay.

(2) circuit longitudinal differential protection synchronization principles and defect thereof

The extensive use of current optical differential current protection, it is formed as shown in Figure 1.The relay protection signal of optical differential current protection system utilizes communication port to transmit both sides protection information.Utilize communication port to pass protected circuit both sides current instantaneous value data mutually, proterctive equipment according to the Current calculation differential current of this side and offside and stalling current, and differentiates troubles inside the sample space or external area error according to result of calculation.

Two proterctive equipment are respectively main frame and from machine, synchronous for the protection of sampling.

At present, the synchronous method that practical line differential protection adopts has sampling instant adjusting method, sampling data correction method and clock correction method, and be referred to as the synchronous method based on data channel, feature all requires that the two-way time delay of passage is equal.Typical sampling instant adjusting method is in two steps: first survey communication channel delay again according to communication channel delay, and by the error measuring both sides device sampling instant from machine, thus adjustment realizes sample-synchronous from the sampling pulse of machine.Channel time delay is tested as shown in Figure 2: set side device as main frame, opposite side is from machine.Power on from machine and just send a frame to main frame and measure the message of communication channel delay, simultaneously with the relative time clock of this side device for benchmark, recorded message delivery time t _ss; After main frame receives this message, with the relative time clock of this side device for benchmark, minute book side receives the moment of message, by the time next timed sending moment t _ms, Xiang Congji replys a frame communication channel delay test packet, this side is received the time difference t of delay test message and reply test packet simultaneously _ms-t _mras message content; From machine at t _srmoment receives the communication channel delay test back message of main frame, and obtains t _ms-t _mr.Communication channel delay T is obtained according to following formulae discovery _d

$T_d=\frac{(t_{\mathrm{sr}}-t_{\mathrm{ss}})-(t_{\mathrm{ms}}-t_{\mathrm{mr}})}{2}---\left(1\right)$

Above formula for the precondition obtaining communication channel delay is: the two-way time delay of passage sending and receiving is equal.The test result of moment difference on communication channel delay of two protective devices does not affect.

Communication channel delay is supposed at a period of time internal channel time delay T after measuring _dchangeless.Sample-synchronous is as shown in Figure 3: main frame with device internal clocking for benchmark, by fixed intervals T _smsample, send electric current message to from machine simultaneously.Receive the electric current message of main frame transmission from machine, main frame can be obtained at what instance sample according to communication channel delay, simultaneously according to this side current sample moment, obtain the error delta T of both sides device sampling instant _s.Now be ahead of main frame sampling instant Δ T from machine sampling instant _s, from the next sampling interval T of machine adjustment _ss> T _sm, make Δ T _s~ 0.As Δ T _sduring < ξ, can think that both sides device achieves synchronized sampling.

In above algorithm, think that duplex channel time delay is on all four, and at short notice give tacit consent to time delay be changeless, therefore protective device using the half of two-way time delay sum as half-duplex channel time delay.After half-duplex channel changes, overall delay changes, this algorithm will the half of overall delay as One Way Delay.Therefore, after half-duplex channel changes, will have an impact to synchronized sampling, and then have influence on the calculating of differential current, the poor flow valuve of display mistake, the serious moment will cause protective device malfunction.

(3) sum up

Owing to lacking the method for testing of strange land One Way Delay, therefore widely used circuit longitudinal differential protection device lacks effective determination methods and the solution of route change.

Circuit longitudinal differential protection has phase selection ability and network topology ability, and not by the impact of system oscillation, open-phase operation, can reflect various types of fault, be desirable power line main protection.The extensive use of current optical differential current protection.Proterctive equipment according to the Current calculation differential current of this side and offside and stalling current, and differentiates troubles inside the sample space or external area error according to result of calculation.Therefore, the passage of transmission line both sides information is the important component part of protection system, has the rigors such as fail safe, reliability and real-time.

Current circuit longitudinal differential protection extensive use, but lack passway by the determination methods changed and regulating measures.

Summary of the invention

The object of the invention is to propose a kind of algorithm, calculated, draw One Way Delay by the time delay of the protective device to circuit two ends, thus judge transmitting-receiving route changing, trigger equipment carries out resampling synchronous adjustment.

The present invention proposes a kind of method being judged differential protection route changing by unidirectional transmission time delay change, comprise the following steps:

First configure two-way route consistent, adopt channel time delay method of testing to test two-way time delay sum, idiographic flow is power on to main frame from machine to send the message that a frame measures communication channel delay, simultaneously with the relative time clock of this side device for benchmark, recorded message delivery time t _ss; After main frame receives this message, with the relative time clock of this side device for benchmark, minute book side receives the moment of message, by the time next timed sending moment t _ms, Xiang Congji replys a frame communication channel delay test packet, this side is received the time difference t of delay test message and reply test packet simultaneously _ms-t _mras message content; From machine at t _srmoment receives the communication channel delay test back message of main frame, and obtains t _ms-t _mr, obtain communication channel delay T according to following formulae discovery _d, because two-way route is consistent, therefore One Way Delay is the half of two-way time delay sum, the initial conditions in this, as this invention:

$T_d=\frac{(t_{\mathrm{sr}}-t_{\mathrm{ss}})-(t_{\mathrm{ms}}-t_{\mathrm{mr}})}{2}$

Then, main frame and increase local message delivery time respectively from machine message, and when local record receives opposite end message, calculate simultaneously and preserve the difference between two moment, send sense for main frame to from machine, concrete steps are:

(1) main frame is to the message marking Tmt1 from machine transmit band if having time, and Tmt1 take host time as benchmark,

(2) receive the time Tsr1 containing Tmt1 message from machine record, Tsr1 with the time from machine for benchmark,

(3) calculate and preserve Δ Tms1=Tsr1-Tmt1,

(4) main frame is at next message delivery time, and to the message from the free Tmt2 of machine transmit band, Tmt1 take host time as benchmark,

(5) receive the time Tsr2 containing Tmt2 message from machine record, Tsr2 with the time from machine for benchmark,

(6) calculate and preserve Δ Tms2=Tsr2-Tmt2,

(7) calculate and preserve Δ Tms2-Δ Tms1;

Constantly repeat by the algorithm of step (1)-(7), calculate and preserve Δ Tms (n)-Δ Tms (n-1), draw time graph, curve is analyzed, draws the abnormity point that the moment changes, can time variations be judged, concrete operations are as follows: the change of the adjacent Δ Tms of record analysis, i.e. Δ Tms (n)-Δ Tms (n-1), when main frame transmission does not change from the unidirectional route that machine receives, this result should be 0; Be not 0 when main frame sends this result when the unidirectional route received from machine changes, if difference be on the occasion of, illustrates that passway is by elongated, propagation delay time change is greatly; If difference is negative value, illustrate that route shortens, propagation delay time diminishes, and finally determines the transmission time of unidirectional route according to time variations value.

The invention has the beneficial effects as follows: the change of two-way route does not need to add hardware device to use method of the present invention to judge; only need carry out part amendment to software; can solve the rigors of differential protection " keep two-way time delay consistent ", the application that differential protection is protected is more extensive.

This invention also can be applicable in the business to propagation delay time sensitive, as PMU etc. in addition.

Accompanying drawing explanation

Below in conjunction with accompanying drawing, the present invention is further described.

Fig. 1 is that optical differential current protection system forms schematic diagram;

Fig. 2 shows communication channel delay and measures;

Fig. 3 shows synchronized sampling;

Fig. 4 shows unidirectional transmission time delay change calculations schematic diagram;

Fig. 5 shows main frame and the calculation flow chart from machine message delivery time difference.

Embodiment

Main frame send out from machine receive circuit time-delay calculation as shown in Figure 4, main frame send from machine receive unidirectional transmission time delay change calculation procedure as follows:

(1) first configure two-way route consistent, and test two-way time delay sum according to Fig. 2 channel time delay method of testing.Because two-way route is consistent, therefore One Way Delay is the half of two-way time delay sum.In this, as the initial conditions of this invention.

(2) main frame is to the message marking (Tmt1) from machine transmit band if having time, and Tmt1 take host time as benchmark.

(3) receive the time Tsr1 containing Tmt1 message from machine record, Tsr1 with the time from machine for benchmark.

(4) calculate and preserve Δ Tms1=Tsr1-Tmt1.

(5) main frame is at next message delivery time, and to the message from the free Tmt2 of machine transmit band, Tmt1 take host time as benchmark.

(6) receive the time Tsr2 containing Tmt2 message from machine record, Tsr2 with the time from machine for benchmark.

(7) calculate and preserve Δ Tms2=Tsr2-Tmt2.

(8) calculate and preserve Δ Tms2-Δ Tms1.

(9) constantly repeat with this, calculate and preserve Δ Tms (n)-Δ Tms (n-1).

The change of the adjacent Δ Tms of record analysis, i.e. Δ Tms (n)-Δ Tms (n-1).When main frame transmission does not change from the unidirectional route that machine receives, this result should be 0; When main frame if to send this result when the unidirectional route received from machine changes be not 0. difference on the occasion of, illustrates that passway is by elongated, propagation delay time becomes greatly; If difference is negative value, illustrate that route shortens, propagation delay time diminishes.

Example is illustrated

Suppose that the every 1ms of protective device sends message, transmission channel duplex channel is consistent, unidirectional transmission time delay be 4ms. protective device when to set up the sample-synchronous aft engine time be 11 point 1 second 000 millisecond, when being 1 from the machine time 1 point 1 second 100 milliseconds.

Passage is unchanged, from machine send containing the time 1 time 1 point of 1 second message of 000 millisecond, from machine in 1 time 1 point 1 second 500 milliseconds receive message.It is 104 milliseconds from machine difference computing time.

In the second moment, passage is unchanged, from machine send containing the time 1 time 1 point of 1 second message of 001 millisecond, from machine in 1 time 1 point 1 second 105 milliseconds receive message.It is 104 milliseconds from machine difference computing time.

The time difference in first, second moment is identical, Δ T1=0 millisecond.

In 3rd moment, passage is unchanged, from machine send containing the time 1 time 1 point of 1 second message of 002 millisecond, from machine in 1 time 1 point 1 second 106 milliseconds receive message.It is 104 milliseconds from machine difference computing time.

The time difference in second, third moment is identical, Δ T2=0 millisecond.

In 4th moment, channel time delay becomes 7ms, from machine send containing the time 1 time 1 point of 1 second message of 003 millisecond, from machine in 1 time 1 point 1 second 110 milliseconds receive message.It is 107 milliseconds from machine difference computing time.

Three, the time difference in the 4th moment is different, Δ T3=3 millisecond.

Thus judge that main frame sends the channel time delay received from machine and changes, and channel time delay increases by 3 milliseconds.

In 5th moment, channel time delay is still 7ms, from machine send containing the time 1 time 1 point of 1 second message of 004 millisecond, from machine in 1 time 1 point 1 second 111 milliseconds receive message.It is 107 milliseconds from machine difference computing time.

Four, the time difference in the 5th moment is identical, Δ T3=0 millisecond.

According to specific exemplary embodiment, invention has been described herein.It will be apparent under not departing from the scope of the present invention, carrying out suitable replacement to one skilled in the art or revise.Exemplary embodiment is only illustrative, instead of the restriction to scope of the present invention, and scope of the present invention is defined by appended claim.

Claims (1)

1. changed the method judging differential protection route changing by unidirectional transmission time delay, comprise the following steps:

First configure two-way route consistent, adopt channel time delay method of testing to test two-way time delay sum, idiographic flow is power on to main frame from machine to send the message that a frame measures communication channel delay, simultaneously with the relative time clock of this side device for benchmark, recorded message delivery time t _ss; After main frame receives this message, with the relative time clock of this side device for benchmark, minute book side receives the moment of message, by the time next timed sending moment t _ms, Xiang Congji replys a frame communication channel delay test packet, this side is received the time difference t of delay test message and reply test packet simultaneously _ms-t _mras message content; From machine at t _srmoment receives the communication channel delay test back message of main frame, and obtains t _ms-t _mr, obtain communication channel delay T according to following formulae discovery _d, because two-way route is consistent, therefore One Way Delay is the half of two-way time delay sum, the initial conditions in this, as this invention:

$T_d=\frac{(t_{\mathrm{sr}}-t_{\mathrm{ss}})-(t_{\mathrm{ms}}-t_{\mathrm{mr}})}{2}$

Then, main frame and increase local message delivery time respectively from machine message, and when local record receives opposite end message, calculate simultaneously and preserve the difference between two moment, send sense for main frame to from machine, concrete steps are:

(1) main frame is to the message marking Tmt1 from machine transmit band if having time, and Tmt1 take host time as benchmark,

(2) receive the time Tsr1 containing Tmt1 message from machine record, Tsr1 with the time from machine for benchmark,

(3) calculate and preserve Δ Tms1=Tsr1-Tmt1,

(4) main frame is at next message delivery time, and to the message from the free Tmt2 of machine transmit band, Tmt1 take host time as benchmark,

(5) receive the time Tsr2 containing Tmt2 message from machine record, Tsr2 with the time from machine for benchmark,

(6) calculate and preserve Δ Tms2=Tsr2-Tmt2,

(7) calculate and preserve Δ Tms2-Δ Tms1;

Constantly repeat by the algorithm of step (1)-(7), calculate and preserve Δ Tms (n)-Δ Tms (n-1), draw time graph, curve is analyzed, draws the abnormity point that the moment changes, can time variations be judged, concrete operations are as follows: the change of the adjacent Δ Tms of record analysis, i.e. Δ Tms (n)-Δ Tms (n-1), when main frame transmission does not change from the unidirectional route that machine receives, this result should be 0; Be not 0 when main frame sends this result when the unidirectional route received from machine changes, if difference be on the occasion of, illustrates that passway is by elongated, propagation delay time change is greatly; If difference is negative value, illustrate that route shortens, propagation delay time diminishes, and finally determines the transmission time of unidirectional route according to time variations value.