JPS63119341A - Sampling synchronizing system - Google Patents

Abstract

PURPOSE:To enable synchronous sampling in all stations by issuing a sampling signal from each station so that this signal precedes specific frame reception by a time operated in accordance with a specific formula. CONSTITUTION:With respect to plural data transmission/reception equipments connected by data transmission line coupled into a loop, one station A as the master station of synchronism transmits a specific frame for sampling synchronism and measures the required for one circulation of the specific frame and transmits this measured data to slave stations B-D as data in the next cycle. Equipments as slave stations of synchronism generate sampling synchronizing signals a certain time to before specific frame reception. This time to in each slave station is operated in accordance with the station number indicating the place of this slave station from the master station, an average inter-station delay time, and time counted data from the master station A.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention utilizes a transmission path connected in a loop to install a plurality of data collection terminals and simultaneously sample the current of, for example, a power transmission line. This relates to a sampling signal synchronization method for

[Background of the invention]

In existing power system protection and control systems, protection and control equipment is installed in a building called a unit room, and connections between the equipment, instrument transformers installed on site, and circuit breakers to be controlled are A wiring method has been used.

Since each of these wirings is used separately for each system protection/control device, the total number of wirings in the substation as a whole is extremely large.

To address this important problem, distributed protection relay systems have been proposed. (Japanese Unexamined Patent Publication No. 58-15419) This eliminates the need to provide a unit room for installing a protective relay device, which has been conventionally used, and also eliminates a huge amount of electrical signal wiring in the substation yard. The main features of the protective relay system proposed in the above-mentioned Japanese Patent Application Laid-Open No. 15419/1982, which provides a protective relay system that is excellent in terms of economy and reliability, are as follows. Become.

(1) Each protection relay device is installed outdoors in a field yard such as a substation near the breaker to be controlled and the CT and PT that are the system information sensors.

And the CT for inputting system information.

The secondary output terminal of the PT and the trip coil of the breaker that provides the control command output are connected to the respective terminals of the protective relay device.

(2) Power is supplied to each protection relay device from a dedicated power supply device built into the device or installed nearby. Note that this power supply device is configured to be completely electrically isolated from other protective relay devices.

(3) Optical signals input from each information detection point to the transmission path shared by the entire system are delivered to all terminals (it is convenient to place them at the same location as the information detection point) at a nearly uniform signal reception level. In order to make it possible to transmit data (without placing a repeater amplifier using an active circuit in the middle of the transmission path, which is likely to lead to a reduction in reliability), the shared transmission path is connected to a star coupler. An information detection device and a protection relay device are placed at the end of each crossroad.

(4) One of the information detection devices is provided with a master clock, and based on this clock, the transmission format (synchronization word and subsequent data word) organized by the information detection device is transmitted over the shared transmission path. Send it towards a certain star coupler.

(5) In each other information detection device, synchronization is established with this transmission format, the synchronization of the clock circuit of the own end is regulated (corrected), the sampling of the own end data, and the own end data in the transmission format is performed. The transmission position (word slot) of the terminal is identified, and the sampling data of the own end is controlled to be transmitted to the star coupler at that time.

(6) The protection relay device installed at each branch end of the star coupler, which is a shared transmission line, is equipped with a data receiving circuit,
The configuration is such that all data words related to its own protection function can be selectively input from the shared transmission path.

This patent publication No. 58-15419 had the following features.

(1) Each terminal device can use a shared transmission path in a time-division manner to transmit its own information to all terminals.

(2) Each terminal device can select and receive only the transmitted information from each terminal necessary for achieving the protection function entrusted to it from among the signals on the shared transmission path.

(3) The shared transmission path is star-shaped.

[Purpose of the invention]

The invention has been described above. JP-A No. 58-15419 uses a star coupler as the transmission line, which is in a star shape, while the transmission line is in the form of a loop, and provides a signal synchronization method that can synchronize the sampling signals. The purpose is to

[Summary of the invention]

The gist of the present invention is that in a plurality of data transmitting/receiving devices connected in a loop by a data transmission path, one of the main stations for synchronization transmits a specific frame for sampling synchronization, and The time it takes for a specific frame to complete one cycle and return is measured, and the measured data is transmitted as data to each slave station in the next cycle. Regarding synchronization, a device that becomes a slave station waits a certain period of time t after receiving a specific frame.
A sampling synchronization signal is generated as early as o, and to is determined by calculation from the station order indicating which station is the station relative to the main station and the average inter-station delay time from the clock data from the main station. This is a unique signal synchronization method.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram showing transmission routes. In the example shown in the figure, A,
An example of four stations B, C, and D is shown.

Among these stations, A is the main station for synchronization, and the transmission route is a loop shown in the order of A-+B→COD→A.

FIG. 2 is a timing diagram illustrating the scheme of the present invention.

Station A transmits to station B a specific frame, Svc, for matching the sampling points of each station to the sampling, signal, and to points of its own station. At station B, this specific frame is transmitted by the transmission delay time (for example, the transmission time when the transmission path is configured with optical fiber, etc.) and the station delay time (the time required to acknowledge the specific frame and send it to the next lower station). It will be recognized late. Let this time be Toa. As shown in the figure, the transmission signal at station B consists of a specific frame emitted from station A and a data frame DATA (A
') as a repeater until the token frame T indicating the end is received, and the own data frame,
DATA (B) is controlled to be transmitted subsequently. The transmission signals of stations C and D are controlled in the same way as station B, and the signal received at station A is transmitted as a signal that goes around each station once as shown in the figure. This transmission cycle is
In a control device or the like, the voltage and current signals of the power system are sampled at a constant period, and the sampling period is usually selected so that the sampling period for AC signals is, for example, every 30 electrical degrees.

On the other hand, the sampling synchronization signal of each slave station is TOR? from the reception of a specific frame Syc. Toa t T
It is generated at an earlier time by ON. These times tOB.

Tact too can occur at the same time as follows.

At the synchronized main station, from the specific frame transmission of the own station,
The time it takes for that particular frame to go around and return is measured,
The time measurement data is transmitted to the slave station as part of the data frame of the next sampling period. Now write this data
DA.

In stations B, C, and D, which are slave stations, the signal was generated at arbitrary times. The sampling signal, the time until the reception of a specific frame is measured, and the time is measured as Toas
Tocp Too ・On the other hand, the transmission delay time and station delay time are fixed values between each station depending on the length of the transmission path, etc., and now they are respectively T OEA and T oE
Let a e T ogc and T DEID. Further, the time of a specific frame can be set as a fixed value by each station using an oscillation clock with sufficient accuracy, and this time is designated as TSY.

When the above is done and the sampling signals of each station are set at the same time, that is, t ov t OReto in the figure
In order for e and too to be at the same time, the following equation only has to hold true.

(a) At station B.

Toa=TSY+TI)E^
−(1)(b) At station 0, T Dc =ToaA+TOEB+TSY
”゛(2)(c) At station D, T Do = T DEΔ+ToaB+ TOEC+
TSY - (3) As mentioned above, the transmission delay time between each station, that is, the time proportional to the length of the transmission path, can be considered to be around 500 m at most within the premises of an electrical station, and variations between each station can be ignored. There is no problem if you do. Therefore,
T DEA y T D of the above formulas (1) to (3)
EB # T DEIC! The delay time TOED from station 0 to station A can be calculated on average from the time To^ measured at station A using the following equation.

Therefore, the above equations (1) to (3) can be simplified as follows.

Equation (1) is Equation (2) is Equation (3) is (To^-Tsy) T oc = X 3 + Tsy
-(3)', and each station has the above-mentioned (1)' to (3)
)' If the sampling signal is emitted before the reception of a specific frame by the time calculated by the equation, synchronous sampling can be performed at all stations.

If the above-mentioned arithmetic expression is expressed as a general expression, it will be expressed as the following expression.

8 However, N: Total number of stations configuring the transmission path n: Ranking from the main station to the own station Tav: Time of a specific frame Ton: Realize the time from the time the sampling signal is issued until the specific frame is received or more. The block diagram of the master station is shown in Figure 3, and the block diagram of the slave station is shown in Figure 4. Shown in I.

The serial data receiving section 1 and the serial data transmitting section are as follows.

This is a serial/parallel converter used for normal data transmission. The frequency of the reference clock pulse ck generated by the reference oscillator 3 is selected to be a sufficiently high frequency fck to keep the sampling synchronization error to a tolerance of 8 or less. In other words, 8Xf
ck>1 is satisfied.

The specific frame detector 4 detects reception of a specific frame, SYC, from the received data RXD. Further, the specific frame generator 5 is provided in the main station and generates a specific frame and a transmission timing signal. In the main station, the timer 6 uses the time To^ from the transmission of a specific frame to the reception of the specific frame after one cycle as a reference clock pulse c.
k, and at the slave station, the time T on from the time the sampling pulse is generated until the reception of a specific frame.
' to time. Sampling synchronization pulse generator 11
Simultaneously with the transmission of a specific frame in the main station, a sampling signal is generated in the slave station in response to a control signal from a sampling synchronization calculation unit.

The above are blocks that operate in the same way on the master station and slave station.
Next, the differences between the master station and slave station will be explained. In the main station, a clock data insertion section 7 is provided, and the clock data To
Insert ^ into the data frame and send it to the slave station. In the slave station, the timing data extraction section 9 receives the T transmitted from the master station.
Extract o^.

The data bypass section 8 bypasses the transmission signal of the higher-ranking station during the time period until the data transmission of the own station. The sampling synchronization signal calculation unit 10 performs To^ and to
n' is a block that executes the calculation of equation (5) above, and this unit causes the slave station to issue a control signal so that the sampling signal S^ is generated at a time 'jDn earlier than the reception of a specific frame. I,
That is, the clock signal ton' is the calculated value tDn of equation (5).
Feedback control should be performed so that it is equal to .

〔Effect of the invention〕

As explained above, according to the sampling synchronization method of the present invention, when the transmission line is in a loop form,
A sampling synchronization system can be configured.

[Brief explanation of the drawing]

FIG. 1 is a transmission line configuration diagram of an embodiment of the present invention, FIG. 2 is a timing diagram showing one row of the sampling synchronization method according to the present invention, and FIGS. 3 and 4 are sampling synchronization methods according to the present invention. It is a block diagram for realizing. 1...Data receiving section, 3...Reference oscillator, 6...
Clock section, data bypass section.

Claims (1)

[Claims] 1. In a plurality of data transmitting/receiving devices connected by a loop-shaped transmission path, any one device is a master station for sampling synchronization, and the other devices are slave stations, and the main station measures the time TDA from the transmission of a specific frame until the specific frame goes around once, and broadcasts the data to the slave station in a data frame, and the device that becomes the slave sends a sampling synchronization signal t_D_N time earlier than the reception of the specific frame. The timing data t_D_ from the sampling synchronization signal to the reception of a specific frame is
N', transmission order n from the main station, number N of transmitting/receiving devices, specific frame length, T_S_Y, T_Dn'=T_Dn=(T_D_A-T_S_Y)/
A sampling synchronization method characterized in that a sampling signal is obtained by the calculation N·n+T_S_Y.