JPH0542210B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a sampling signal synchronization method used, for example, in a protective relay device for power transmission lines.

[Conventional technology]

In a digital protective relay device, the current at both ends is
Carrier relays, which are converted into PCM (Pulse Code Modulation) and compared with each other, have come into use. In this comparative protective relay device, the instantaneous values of currents at both end stations of a power transmission line are sampled at regular intervals, A/D converted, and then transmitted to the other station using, for example, a micro line. System failures in power transmission lines are monitored by comparing with station values.

In this case, the sampling timing at both end stations must be the same time, and the time from when data is sent until it is received by the other station, that is, the transmission delay time, is larger than the sampling period and several times that period. Therefore, a series of repetition numbers must be assigned to the sampling timing, and data sampled at the same time at both terminal stations must be assigned the same number and transmitted. In the protective relay device of this type, a means of synchronizing the sampling timing and the sampling number is a very important issue.

Conventionally, this type of signal synchronization system has already been proposed in Japanese Patent Application Laid-open No. 49645/1983. This conventional method will be briefly explained.

FIG. 4 is an explanatory diagram showing the principle of the conventional system.
Here, the terminal station that takes the initiative in synchronization is called the "master station",
The terminal station on the slave synchronization side will be called the slave station.

It depicts the temporal relationship regarding the transmission and reception of data of a specific sampling number (hereinafter, the data sent from the master station to the slave station is abbreviated as S ₁ , and the data transmitted from the slave station is abbreviated as S ₂ ). It is assumed that the time it takes S ₁ to arrive at the slave station and the time it takes S ₂ from the slave station to arrive at the master station are virtually negligible and equal to each other, and this is defined as the transmission delay time Td.

In this way, a transmission path with equal vertical transmission delay times can actually be constructed. Further, there is a precondition that the transmission period T of S ₁ and S ₂ is at least twice the maximum value of Td taking into account fluctuations.

In FIG. 4, the time from the transmission of S ₁ at the master station to the reception of S ₂ is defined as T ₁ , and this time is measured at the master station, and from the transmission of S ₂ at the slave station,
Assuming that the time until reception of _S1 is _T2 , the slave station measures this time _T2 . And the main station is the above time
_T1 is loaded onto the data transmission format and sent to the slave station, which receives this _T1 . Also,
Conversely, the slave station sends the time _T2 to the master station, and the master station receives it.

At this time, a in FIG. 4 is a case where the downward diagonal line indicating the transmission of S ₁ from the master station and the upward diagonal line indicating the transmission of S ₂ from the slave station intersect with each other.
The case where the relationship T ₁ +T ₂ =2Td is established is shown.

In Fig. 4 a, the transmission of _S2 from the slave station is delayed in time from the transmission of _S1 from the master station, and the phase (timing) of the clock pulse of the slave station transmitter is slightly advanced. It can be seen that the entire transmission from the slave station must be moved to the left as shown by the arrow in the figure. That is, it can be determined that if T ₁ > T ₂ , the transmission from the slave station should be accelerated, and if T ₁ <T ₂ , it is necessary to delay the transmission from the slave station.

This may be done by controlling the phase of the clock pulse at only one end station, or at both end stations, so that T ₁ =T ₂ . If T ₁ = T ₂ , it means that S ₁ and S ₂ were transmitted at exactly the same time, and therefore all operations including data of other sampling numbers are performed by the main station. This will be done at the same time with the slave station, and the synchronization of the sampling signals will be perfect.

Using the above method, the sampling timing of the master station and slave station is adjusted by matching the transmission timing of data S ₁ and S ₂ of the same predetermined sampling number.
Match the timing. At this time, either the main station or the slave station advances the phase of the clock pulse to match the sampling timing, or
Adjustment is performed by delaying or adjusting, but this adjustment time width is based on the data S ₁ and S ₂ of a specific sampling number.
The maximum time is 1/2 of the transmission period T. If the sampling timing is shifted, that is, the adjustment time width is shifted all at once, the timing of data transmission will suddenly change, resulting in a received data error at the receiving end, so in practice The sampling timing is shifted by an extremely short time within a range that does not cause a received data error, and this is repeated multiple times to shift the final adjustment time width. For this reason, it took a long time to synchronize the sampling signals. Also, the time measured to take the sampling period,
In other words, the own station receives data of a specific sampling number.
The time from transmitting S ₁ or S ₂ to receiving data S ₂ or S ₁ of the same sampling number from the other station can be measured as the period T of transmitting data of a specific sampling number. things are necessary. Depending on the time measurement accuracy, a time measurement counter with a relatively large number of bits is required.

Therefore, the number of bits of the time data (T ₁ or T ₂ ) to be transmitted to the partner station is also large, and occupies a large number of bits on the transmission format.

Furthermore, in the method disclosed in Japanese Patent Application Laid-open No. 50-49645, each of the master station and the slave station measures the time required to take the sampling period, and the measured time data is transferred from the master station to the slave station, and from the slave station to the master station. It has become an essential condition to be able to transmit data to and from each other.

For this reason, the above-mentioned time measurement data must be included in the data transmitted to the partner station, which imposes restrictions on the transmission format and impairs transmission efficiency. Figure 4b shows the case where S ₁ and S ₂ do not intersect, but as in Figure 4a, it is necessary to ensure that S ₁ and S ₂ are transmitted at exactly the same time, and as described above. of
There is the same problem as when S ₁ and S ₂ intersect.

[Problem that the invention seeks to solve]

In the sampling synchronization method disclosed in Japanese Patent Application Laid-open No. 50-49645, in order to match the sampling timing, it is necessary to shift the specific data by a maximum of 1/2 of the transmission cycle T, and it takes a long time to achieve synchronization. Was. Further, the measurement time for synchronization adjustment is required for the above-mentioned transmission period T, and the number of bits is large, requiring a large amount of circuitry and hardware for time measurement.

Furthermore, the measured time data for synchronization adjustment must be transmitted to and from the other station, which reduces the transmission efficiency of the system and requires a large amount of data length in the transmission format. First, there were problems such as poor transmission efficiency.

This invention was made in order to solve the above-mentioned problems, and it is possible to match the sampling timing of the main station and the slave station in a short time, and
It completely eliminates the need to transmit time data between opposite stations that perform synchronization adjustment, making the transmission efficiency extremely high, and the time measurement at the synchronization adjustment station can be performed in a short time and the number of bits of time data can be reduced. The purpose of this invention is to shorten the time, reduce the amount of hardware, and obtain a sampling synchronization control method that can be performed without mutual transmission of time data.

[Means for solving problems]

The sampling signal synchronization method according to this invention is
When a master station or a slave station receives data with a specific sampling number, the reception timing of the master station and the transmission timing of the slave station must match, or if the two timings are out of sync, check the timing. After a certain sampling interval, flag information instructing adjustment for matching is returned to the other station, and either the main station or the slave station measures the time from the most recent sampling timing until receiving the flag information, By recognizing the time from when the own station transmits data with a specific sampling number until receiving the above flag information, the transmission delay time with the other station is calculated, and sampling is performed by moving the sampling timing of the own station. The timing is synchronized and the sampling numbers are controlled to match.

[Effect]

In the sampling signal synchronization method of this invention, data indicating a specific sampling number is transmitted from the slave station to the master station, and when the master station receives data of this specific sampling number, the sampling timing of the master station and the reception timing from the slave station are synchronized. If they do not match, flag information indicating "advanced control" or "delayed control" is returned to the slave station at the master station sampling timing immediately after receiving the data of the specific sampling number. If the sampling timing of the master station and the timing of reception from the slave station completely match, the master station returns flag information indicating "match" to the slave station at the next sampling timing of the master station. That is, after a fixed sampling interval (in this case, one sampling timing), flag information indicating "timing match" is returned to the other station.

The slave station receives the flag information indicating this "timing match," but at this time, it measures the time from the slave station's most recent sampling timing until it receives the flag information, and automatically waits for 1/2 of this measured time. The sampling timing of the station (here, the slave station) is controlled to be shifted so that only the sampling timings of the master station and the slave station match.

At this time, the transmission timing of the slave station is not changed and is fixed, and only the sampling timing of the slave station is changed.

Then, the number of sampling timings (i.e., the number of sampling cycles) of the own station is measured from when the slave station transmits data of a specific sampling number until the other station returns flag information indicating reception of data of this specific sampling number. However, by recognizing this, it is possible to know the transmission delay time Td on the transmission path from the own station to the other station, and it is possible to know the difference in sampling number with the other station. Therefore, the sampling number of the own station is changed so as to eliminate the sampling number difference with that of the opposite station, and both the sampling number and the sampling timing are made to match, and the sampling signals of both end stations are synchronized.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. In FIG. 1, T represents the period of the sampling number, which here is one cycle (equivalent to 360 electrical degrees) at the frequency of the power system (50 Hz or 60 Hz). T ₀ is the sampling timing period, which is assumed to be 30 electrical degrees here. Data of a specific sampling number is transmitted from the slave station to the master station in S2. In FIG. 1, the specific sampling number is set to "0".

Ts is the time from the previous sampling timing when the slave station receives data carrying flag information Fm indicating that data S2 of a specific sampling number has been received from the main station, which is the other station.

The flag information Fm indicates that the main station has received data S2 with a specific sampling number from the other station, and whether the reception timing completely matched the sampling timing of the own station, that is, the main station.
This is flag information that also has the meaning of indicating whether or not it was off.

FIG. 1 is an explanatory diagram showing the principle of the present invention, and depicts the temporal relationship regarding transmission and reception of data between a master station and a slave station. It is assumed that the time required for the flag information Fm sent from the main station to arrive at the main station is virtually negligible and equal to each other, and this is defined as the transmission delay time Td.

In FIG. 1, to explain the operation first, the sampling timing at the main station and slave station is set at intervals of 30 electrical degrees. Therefore, a sampling number is assigned to each sampling timing, and the sampling numbers are 0, 1, 2, 3,...
...Represented by 12 numbers: 9, 10, 11. Sampling timing interval T ₀ between master station and slave station
shall be equal to each other.

The slave station transmits data S2 of a specific sampling number at regular intervals (T=T ₀ ×12).
S2 transmitted from the slave station arrives at the master station after a transmission delay time Td. At this time, the main station checks and determines whether the sampling timing of its own station and the reception timing at which data S2 arrives completely match. When the master station receives S2 from the slave station, it always sends flag information Fm indicating "S2 reception" (hereinafter referred to as flag Fm) to the transmission data to the slave station at the next sampling timing. Send data to slave station. In the example shown in Figure 1, S2 from the slave station is received when the master station has sampling number "9", and the master station adds flag Fm to the transmission data of sampling number "10", and sends the signal from the master station to the slave station. Reply to The slave station receives the flag Fm from the master station, and in order to know the time from when the own station transmits data S2 to when the slave station receives the flag Fm, the flag Fm reception timing is set to the sampling number "7" of the own station. ”. Then, among each sampling timing, the time from the sampling timing immediately before flag Fm arrives until flag Fm is received is calculated.
Measured as Ts.

First, the first stage of sampling timing synchronization control between the master station and the slave station will be explained based on FIGS. 1 and 2.

When the data S2 transmitted from the slave station arrives at the master station and the timing of reception completely matches the sampling timing (30° interval) of the master station, that is, the transmission timing of the master station, the master station sets a flag F0 indicating "timing match". is transmitted to the slave station at the next transmission timing of the master station.

That is, the flag F0 is necessarily returned to the slave station at a timing delayed by one sampling timing _T0 from the data S2 reception timing.

Next, if the reception timing of data S2 from the slave station is different from the transmission timing of the master station, the master station applies "advance control" or "delay control" to the slave station.
The flag information, F1 and F2, respectively, are returned at the next transmission timing.

Depending on the operation of the master station as described above, the slave station receives the "advance control" or "delay control" flag F from the master station.
1 or F2, the slave station's transmission timing is controlled to slightly advance or delay the phase (timing) of the clock pulse of the slave station transmitter, according to the flag F1 or F29 instruction from the master station.

As a result, the transmission timing of data S2 from the slave station shifts little by little in the direction of arrow A in the example of FIG. In other words, there comes a time when the sampling timing completely matches. In this case, the transmission format has a sampling number that repeats at regular intervals based on the sampling timing, and cyclic transmission and reception timings that are the same as the sampling timings described above, so even if the transmission and reception timings of each station are different, , the flag information sent from the master station to the slave station is as follows:
The slave station's transmission timing can be either the "advance control" flag F1, which advances the transmission timing of the slave station on the time axis, or the "delay control" flag F2, which delays the transmission timing of the slave station. The timing can be made to match the reception timing of the main station. As mentioned above, moving in the direction of arrow A can take less time to match the timing than moving in the opposite direction, but either way the timing can be matched in a short time. It doesn't change what you can do. When the reception timing of data S2 at the master station and the transmission timing of the master station completely match, the master station transmits a flag F0 indicating "timing match" to the slave station.

When the slave station receives the flag F0, it stops the phase control of the slave station transmitter and fixes the transmission timing at that point.

Then, the slave station transmission timing is fixed and does not change until the flag F1 or F2 is received from the master station again. During the period when this flag F0 is being transmitted, a certain relationship is established between the transmission timings of the master station and the slave station.

Furthermore, in order to know the time from when the slave station sends data S2 until it receives flag F0, the slave station measures the time from the sampling timing immediately before flag F0 arrives until it receives flag F0 as Ts. do.

Figure 2 shows a state in which the reception timing of data S2 from the slave station completely coincides with the transmission timing of the master station, or in other words, the sampling timing of the master station, and the flag F0 is transmitted from the master station to the slave station. This is a state in which a certain relationship has been established between the master station and the slave station.

In this state, control is performed to match the sampling timings of the master station and slave station. As is clear from FIG. 2, the following relationship holds true between the transmission delay time Td, the sampling timing difference Δt between the master station←→slave station, and each sampling period _T0 and measurement time Ts.

0≦Ts≦T ₀ …(1) formula Tk ₁ =m×T ₀ +Ts (however, m is an integer) …(2) formula Tk ₂ =2Td+T ₀ …(3) formula Td=nT ₀ +Δt…(4) formula m = 2n + 1 (where m and n are integers) ...Equation (5) When calculating the sampling timing difference Δt from the above equations (2), (3), (4), and (5), the value of equation (6) is obtained. becomes.

Tk ₁ = Tk ₂ (2n + 1) T ₀ + Ts = 2 (nT ₀ + Δt) T ₀ Δt = 1/2Ts (6) Therefore, in order to make Δt zero, the time Ts measured at the slave station must be This means that it is only necessary to adjust the sampling timing on the slave side by 1/2 the value. However, if the transmission timing of the slave station is shifted by the value of 1/2Ts, the transmission timing of data S2 sent from the slave station to the master station will change, so the timing of arrival of data S2 on the master station side will also change. It becomes impossible to transmit the "timing match" flag F0. Therefore, the slave station performs control to shift the internal sampling timing of the slave station by the value of 1/2Ts, without changing the data transmission timing from the slave station to the master station.

That is, in the main station, the data transmission timing and the sampling timing are the same, but in the slave station, the data transmission timing and the sampling timing are different.

However, since the original purpose is to completely match and synchronize the sampling timing between the master station and the slave station, there is no problem even if the transmission timing and sampling timing of the slave station do not match.

Next, control is performed to match the sampling numbers of the master station and the slave station. FIG. 1 also shows the state after performing the control to make the sampling timing difference zero, in which the master station receives data S2 of the specific sampling number "0" from the slave station, and the immediately following sampling timing "10", a flag Fm indicating "S2 reception" is loaded and transmitted to the slave station. The slave station stores its own sampling number RA "7" when this flag Fm arrives, and also recognizes the sampling number SA "10" of the transmission data from the master station that has carried the flag Fm.

The fact that the flag Fm from the master station arrived at sampling number "7" of the slave station means that Equations (2) and (3) are
From equation (4), the transmission delay time Td between the master station and slave station is
Td = (m-1/2) T ₀ + Ts/2, and the sampling number of the data sent from the master station with flag Fm is "10" means that the sampling number of the slave station is "10". 6 compared to that of the main station.
You can see that it is ahead by 6 points (lags behind by 6 points). This state can be expressed mathematically as equation (7). ε
indicates the number of delays in the sampling number of the master station relative to the slave station.

ε=SA−RA+1/2 …Equation (7) In the example in Figure 1, since SA=10 and RA=7, ε=
6, indicating that the slave station is behind the master station by 6 sample numbers. (7) In the formula, SA takes an integer value of 0 to 11, and RA takes an odd value of 1 to 11.
FIG. 3 shows the relationship between the ε value and the sampling number between the master station and the slave station.

The slave station can know the sampling number difference with the master station from the ε value, and changes the sampling number at its own station so as to eliminate the sampling number difference with the partner station. In the example of FIG. 2, sampling number 8 is advanced by 6 samplings to become sampling number 2. The method of change is to add the ε value to the sampling number of the slave station, take the remainder only when it exceeds 12, and otherwise use the same value as the sampling number of the new slave station.

Note that in the above embodiment, the sampling timing and sampling number were controlled in the slave station, but on the contrary, the same effects as in the above embodiment can be achieved by performing similar calculations and control in the master station. play.

In the above embodiment, the sampling timing and sampling number were controlled in the slave station, but in order to match the sampling timing in both the master station and slave station, the timing of receiving data from the slave station and the transmission timing of the master station By adjusting the phase of the own station's transmission timing (control to change it) to make it match, the time required to synchronize the sampling timing is halved, making it possible to achieve even higher speeds. Regarding the synchronization of sampling numbers, it is necessary to perform control in either the master station or the slave station, but the same effect as in the above embodiment can be obtained regardless of whether the synchronization is performed in either.

In addition, in the above embodiment, at the main station transmission timing immediately after receiving data of a specific sampling number,
Although the flag information is returned, the same effect as in the above embodiment can be obtained even if the flag information is returned after a certain sampling interval after receiving the data or after a fixed delay that does not change.

In the above embodiment, the case between two stations, the master station and the slave station, was explained, but it may also be the case between three or more stations. Synchronization is achieved by If the remaining one station is then synchronized with one of the two synchronized stations using the same control as in the embodiment, the same effects as in the embodiment described above can be obtained.

In addition, although the above embodiment describes the case of a protective relay device, it may also be a seismometer, a standard clock, etc. that requires synchronization between distant points, and the same effect as in the above embodiment can be obtained. play.

In addition, in the above embodiment, the flag information has both flag information indicating that a specific sampling number has been received and flag information indicating the temporal coincidence between the data arrival timing and the own station transmission timing, but the meanings of both are different. A similar effect can be obtained even if the information is separated into separate flag information.

〔Effect of the invention〕

As described above, according to the present invention, when a specific sampling number is received from a slave station to a master station, matching control of sampling timing can be performed using only the single bit information sent back to the other station. The time data to be measured can also be measured using only one amount of time data from only one slave station. Therefore, the slave station only needs hardware for one time measurement counter.
The main station only needs to check whether the reception timing and transmission timing match, and this also requires extremely simple hardware, making it possible to construct an inexpensive and highly reliable system. Furthermore, since there is no need to transmit time data, there is an effect that the transmission efficiency can be increased.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the principle of a sampling signal synchronization method according to an embodiment of the present invention, and FIG.
Time chart showing the transmitted and received signals when the reception timing and transmission timing at the main station match, Part 3
The figure shows the sampling number difference and the sampling number relationship between the master station←→slave station, and FIG. 4 is an explanatory diagram showing the principle of the conventional sampling signal synchronization method.

Claims (1)

[Claims] 1 Using opposing transmission lines, station A sends and receives data in the same cyclic transmission format with a sampling number that repeats at a constant cycle.
In a transmission method between stations B, when the period T in which the same sampling number occurs is greater than twice the transmission delay time of each, station A transmits a signal with a specific sampling number on the transmission format at a constant period. However, station B, which is the other station, compares the timing of the arrival of the signal with the above-mentioned specific sampling number from station A and the transmission timing of its own station (station B), and notifies them of the match or mismatch. and sends back flag information indicating that the signal with the specific sampling number has been received, either immediately after receiving the signal with the specific sampling number or at the transmission timing of the own station (station B) after a certain time delay, and Based on the flag information sent back from station B, the station adjusts the transmission timing of its own station (station A) until it receives flag information from the other station, station B, that indicates "timing match." Changes and adjustments are made, and in a state where the data arrival timing at the B station and the B station's transmission timing match in time, the time from the A station's most recent transmission timing to the reception of the above flag information on the A station side. From the sampling number indicating the own station transmission timing when station A receives the above flag information, the sampling number of the partner station that sent the flag information, and the measurement time of the above measured quantity, the own station This sampling signal synchronization method is characterized in that the timing difference between occurrence of the same sampling number of the A station and the opposite station is determined, and the sampling timing of the A station is adjusted in order to make the timing difference "0".