JPS6324497A - Sampling signal synchronization method - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

[Conventional technology]

Generally, in digital power transmission line protection relay devices.

The current at both ends is P CM (Pulse Code Mod
Carrier relays have come into use that compare each other with each other. This comparison-type power relay device samples and A/D converts the instantaneous value of the current at both end stations of a power transmission line at a constant cycle, and then transmits it to the other station using, for example, a micro line. System failures in power transmission lines are monitored by comparing the values with sampling values at stations.

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. It is normal. Therefore, a series of repeating 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 such a signal synchronization type protective relay device, 1. A means of synchronizing the sampling timing and the sampling number is a very important issue. FIG. 3 is a principle diagram showing the conventional sampling signal synchronization method disclosed in, for example, Japanese Unexamined Patent Publication No. 50-49645. In the figure, Sl, S are data of a specific sampling number (
(hereinafter abbreviated as S, ,S), T is the time from the transmission of Sl at the master station to the reception of S, and T2 is the time from the transmission of Sl at the master station to the reception of S at the slave station.
The time from transmission of 8 to reception of S, and T is S, ,S
, indicates the transmission cycle of .

Next, the operation will be explained. The temporal relationship regarding the transmission and reception of data of a specific sampling number (S is data transmitted from the master station to the slave station, S2 is a signal transmitted from the slave station) is shown in FIG. 3 in abbreviated form. First, it is assumed that the time it takes for data S sent from the master station to arrive at the slave station and the time it takes for data S sent out from the slave station to arrive at the master station are virtually negligible and equal to each other, and this is then transmitted. delay time T
Let it be d.

In this way, a transmission path with equal vertical transmission delay times can actually be constructed. Further, there is a precondition that the transmission cycle T of the data S4 and S2 is at least twice the maximum value of the transmission delay time Td taking into account fluctuations.

Then, the time T2 from the transmission of data S1 at the master station to the reception of data S2 is measured at the master station, and the time T2 from the transmission of data S2 at the slave station to the reception of data S2 is measured at the master station.
is measured at the slave station. Then, the master station puts the time T on the data transmission format and sends it to the slave station,
The slave station receives time T. Conversely, the slave station sends the time T2 to the master station, and the master station receives it.

At this time, in FIGS. 3(a) and (b), the downward diagonal line indicating the transmission of data S1 from the master station and the upward diagonal line indicating the transmission of data S from the slave station intersect with each other. , time T, +T2=2Td. This figure 3 (a) shows the data S from the slave station.
This is a case where the transmission of data S1 from the main station is delayed in time from the transmission of data S1 from the main station, and the phase (timing) of the clock pulse of the slave station transmitter is slightly advanced, so that the transmission from the slave station as a whole is as shown by the arrow in the figure. You can see that you need to move it to the left. That is, if T,>T, it is determined that the transmission from the slave station should be advanced, and if T1<T, it is determined that the transmission from the slave station needs to be delayed.

This is done by controlling the phase of the clock pulse at only one end station, either the master station or the slave station, or at both end stations.
It may be controlled so that = T.

If T, = T2, it means that data S8 and S of a specific sampling number were transmitted at exactly the same time, and therefore all operations including data of other sampling numbers are performed. The main station and slave station perform the sampling at the same time, and the sampling signals are perfectly synchronized.

In the above method, the sampling timings of the main station and the slave station are matched by matching the transmission timings of the data S, , S2 having the same predetermined sampling number. At this time, should either the main station or the slave station advance the phase of the clock pulse in order to match the sampling timing?

Adjustment is made by delaying or adjusting, but the adjustment time width is at most 1/2 of the transmission cycle T of the data S, , S, of a specific sampling number. If the time by which 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.

For this reason, 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.

Also, the time measured for sampling synchronization, that is, the time from when the local station transmits data S or S2 with a specific sampling number until receiving data S2 or Sl with the same sampling number from the other station is , it is necessary to be able to measure the period T of transmitting data of a specific sampling number. Although it depends on the time measurement accuracy, a time measurement counter with a relatively large number of bits is required.

Therefore, the time data (T1 or T2
), which occupies a large number of bits in the transmission format.

[Problem that the invention seeks to solve]

Since the conventional sampling signal synchronization method is configured as described above, in order to match the sampling timing, it is necessary to shift the specific data by a maximum of 1/2 of the transmission period T, which makes synchronization difficult. It took a long time. Furthermore, the measurement time for synchronization adjustment is also required for the above-mentioned transmission cycle T.

The number of bits is large, and the transmission format requires a large data length, resulting in problems such as poor efficiency.

This invention was made to solve the above-mentioned problems, and it allows the sampling timings of the master station and slave station to match instantaneously, and it also makes it possible to measure one hour in a short time and shorten the number of bits of time data. [Means for solving the problem] The sampling signal synchronization method according to the present invention aims to obtain a sampling signal synchronization method with improved transmission efficiency. The time from the previous sampling timing to the reception of data with a specific sampling number is measured, and the measured time is mutually transmitted between the master station and the slave station, and the master station and slave station confirm that the data with the specific sampling number has been received. The indicated flag information is mutually transmitted.

Then, the sampling timing is instantaneously controlled so that the measurement times are compared and matched, so that they match at once, and the sampling numbers are controlled to match based on mutually transmitted flag information.

[Effect]

The sampling signal synchronization method in this invention measures the time from the sampling timing immediately before receiving data of a specific sampling number to the reception of data of a specific sampling number, and compares the time data transmitted between the master station and the slave station. The transmission timing is controlled so that the values are equal. Then, only the sampling timings of the master station and the slave station are matched.

Next, measure the number of sampling timings of the own station from when the own station transmits data with a specific sampling number until the other station returns flag information indicating reception of data with this specific sampling number. By doing this, the transmission delay time Td of the transmission path from the local station to the other station is known. This makes it possible to know the difference in sampling numbers between the own station and the other station, and changes the sampling number of the own station so as to eliminate the difference in sampling numbers between the own station and the other station. Then, both the sampling timing and the sampling number are made to match, and the sampling signals of both stations are synchronized.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same parts as in FIG. 3 are shown with the same symbols. T represents the period of the sampling number,
Here, the frequency of the power grid (50 lines or 60 Hz)
This is one cycle (equivalent to 360 electrical degrees). T
, is the period of sampling timing, the electrical angle is 30 degrees, and the specific sampling number is "0".

In addition, TM is transmitted from the slave station, which is the partner station, at the master station.
Ts is the time from the previous sampling timing when data S with a specific sampling number is received or data with flag information F1 is received, and Ts is the time when data S with a specific sampling number is received from the master station in the slave station.
, or when data carrying flag information F2 is received, from the previous sampling timing.

The flag information Fl and F2 are the main station and slave station, respectively.
Specific sampling number data S1 from the partner station. This is a flag indicating that S is received.

It is assumed that the time taken for data S□ sent from the master station to arrive at the slave station and the time taken for data S2 sent out from the slave station to arrive at the master station are equal to each other, with virtually negligible difference. This is defined as transmission delay time Td.

Next, FIG. 2 shows an example of the present invention in which the current difference is 1jJ'
A system configuration diagram (configuration for one terminal) when used in an electric device is shown. In a specific embodiment, the first and second devices necessary for data transmission as shown in FIG. 2 are positioned as a local station and another station. First, the current differential relay device 1 includes an analog filter 2, a sample hold 3, an A/D
It is composed of a system current input section of the converter 4, a local station data transmitting section 5, an other station data receiving section 6, a differential calculation means section 7 having a microprocessor, and a sampling synchronization control (means) section 8. In the current differential relay device 1, from the power transmission line to the CT
After sampling the instantaneous values of the currents at both end stations from a large input at a constant cycle and A/D converting them, they are mutually transmitted to the other station via the receiving end and the multiplex converter 9 using the PCM transmission method. (via optical fiber, etc.) to monitor system failures in power transmission lines by comparing the values with those of each station. In this case, the sampling period control unit 8 synchronizes the sampling signal SAM of the local station with the sampling signal of the other station, and performs differential calculation during the synchronized period. If synchronization is not achieved, no calculation will be performed and the relay device will be in a locked state.

Next, the operation shown in FIG. 1 will be explained. First, the sampling timing at the main station and the slave station is set at intervals of 30 electrical degrees. Therefore, sampling numbers are assigned to each sampling timing, and the sampling numbers are 0, 1, 2, 3°...9, 10.11 and 12.
expressed as a number.

Sampling timing interval T in master station and slave station
. shall be equal to each other.

Data S4 and S2 of specific sampling numbers are transmitted from the master station and the slave station at regular intervals (T=T, X12). Data S transmitted from the master station is received by the slave station after a transmission delay time Td. At this time, in the slave station, the total time H111 from the sampling timing immediately before the data S is received to the reception of the data S1 among the sampling timings is set as Ts and the total time is t11. When the slave station receives data S1 from the master station, it always adds "S1" to the transmission data to the master station at the next sampling timing.
Data is transmitted from the slave station to the master station with flag information F1 indicating "reception". In the example of FIG. 1, the slave station receives data S from the master station when the sampling number It I 11, and the slave station receives the data S from the master station when the sampling number It I 2 ++
The flag information F1 is placed on the sent data a and transmitted from the slave station to the master station. At this time, the measurement time Ts measured earlier by the slave station is also transmitted to the master station. The main station takes a total of 81g as TM of the measured time from the sampling timing immediately before receiving data S2 to receiving data S2 among each sampling timing. When the master station receives data S from the slave station, it always sends the data "S" to the slave station at the next sampling timing.

Flag information F2 indicating "reception" is loaded.

The master station controls the timing so that 'r, = 'r5 at a certain sampling timing based on the total time T5 transmitted from the slave station and the measurement time TM of its own station, and instantaneously connects the master station. Match the sampling timing of slave stations. Depending on the difference in measurement time TM=T5, a reception data error may occur at the receiving end, but this is not a problem since data when the sampling timings do not match cannot be used.

Next, the slave station receives flag information F1 indicating "S, reception" from
The sampling number of the master station, the measurement time Ts transmitted from the slave station, and the measurement time T of the own station when the master station receives
From M, the transmission delay time Td between the master station and the slave station is determined as shown in equation (1).

Td=((sampling number when the main station receives flag F2))xTo+TM+Ts/2
(1) When the main station receives a specific sampling number in this manner, the sampling number deviation N of the main station with respect to the slave station is determined from the sampling number of the main station, the transmission delay time Td, and the measurement time TM.

N = (Sampling number of the master station when the specific sampling number is received at the master station) - (Td - TM) By shifting the sampling number of the master station by N as shown in equation (2), the master station and slave station The sampling numbers of can match.

In addition, in the above embodiment, the time to be measured is explained as the time from the sampling timing immediately before receiving the data of the specific sampling number to the receiving of the data of the specific sampling number, but it is the time from the receiving of the data of the specific sampling number to the sampling timing immediately after that. It may be the time of

Furthermore, in the above embodiment, the sampling timing and sampling number are controlled in the main station.
By performing similar calculations and control at the slave station,
The same effects as in the above embodiment are achieved.

Furthermore, in the above embodiment, the case of a protective m-type device was explained, but it may also be a seismometer, a standard clock, etc. that requires synchronization between points with a certain distance, and the same device as in the above embodiment may be used. be effective.

〔Effect of the invention〕

As described above, according to the present invention, since the master station and the slave station measure the reception time of data with a specific sampling number and control the sampling timing so that the coincidence caused by one control of the sampling timing coincides with the sampling number,
The sampling timing can be matched instantaneously, time can be measured in a short time, and the number of bits of time data can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a principle diagram showing a sampling signal synchronization method according to an embodiment of the present invention, FIG. 2 is a system configuration diagram of a current differential relay according to an embodiment of the present invention, and FIG. 3 is a diagram showing a conventional sampling signal synchronization system. It is a novel diagram showing a synchronization method. In the figure, SL, S, specific sampling number patent applicant Mitsubishi Electric Corporation Ni Td 2 l, Yun Send i g'r F+m 4 Figure 3 (o) Figure 3 (b)

Claims (1)

[Claims] In the sampling signal synchronization method, first and second devices for transmitting and receiving sampling data are provided at both ends of opposing transmission paths, and transmitting and receiving transmission format data of the same sampling with a sampling number added at a constant cycle. The measurement time from the sampling timing to the reception of the specific sampling number in the first device, or the measurement time from the reception of the specific sampling number to the sampling timing, and the measurement time from the sampling timing to the reception of the specific sampling number in the second device. Compare the time or the measured time from reception of a specific sampling number to the sampling timing, and instantly control the sampling timing of the device or the second device with a single operation so that the compared time difference becomes zero. When the first device receives a specific sampling number, it sets a flag on the transmission format and transmits it, and when the second device receives the specific sampling number, it transmits the transmission format. sampling synchronization control means for causing sampling numbers of the first device and the second device to match in the first or second device by transmitting a flag on the first device; A sampling signal synchronization method characterized in that sampling operations of devices are performed at the same time.