JPH0417509A - Sampling synchronization unit - Google Patents

Abstract

PURPOSE:To obviate the necessity of special large capacity transmission line by correcting the sampling timing based on the sampling synchronization shift at each terminal which is calculated based on a branch voltage obtained from voltage and current at each terminal. CONSTITUTION:Voltages and currents at the terminals Ass-Dss of a transmission line 1 are inputted to the data processing sections 7a, 7b, 7c, 7d of terminals 6a, 6b, 6c, 6d disposed at respective terminals and then transmitted from data transmitting sections 8a, 8b, 8c, 8d on transmission lines 12a, 12b, 12c, 12d to a CPU 9. The CPU 9 receives data from respective terminals at a transceiver section 10 and an operating section 11 determines the sampling phase shift at each terminal which is then transmitted from the transceiver section 10 on the transmission lines 12a, 12b, 12c, 12d to each terminal unit. Each terminal unit corrects its sampling timing according to the sampling phase shift transmitted from the CPU.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a sampling synchronization device that synchronizes the sampling timing of the amount of electricity at each terminal of a power transmission line having two or more terminals.

(Conventional technology) As a method of synchronizing each terminal of sampling timing, with the recent development of transmission technology, it is possible to synchronize the sampling timing between both terminals by
? There is a method of connecting by I transmission, transmitting and receiving synchronization signals, and creating simultaneous reference signals at both ends.

This method has already been put into practical use with current-operated relays that protect power transmission lines using digital relays. However, this method has disadvantages in that the transmission equipment is complicated and a large capacity transmission path is required. (For example, Tokuko Sho 57
(Publication No. 50262) (To be solved by the invention) As mentioned above, the sampling synchronization method for voltage and current data at each terminal of a power transmission line requires a large-capacity transmission line and requires a complicated device. It had the disadvantage of becoming

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sampling synchronization device that simplifies the transmission device and does not require a large-capacity transmission path.

Configuration of the Invention (Means for Solving the Problem) In order to achieve the above object, the sampling synchronization device of the present invention performs sampling of input voltage and current data in a terminal device installed at each terminal of a power transmission line. It is synchronized, and the terminal device uses voltage.

A means for sampling and inputting current, a means for transmitting voltage and current data to a central processing unit, a means for receiving a deviation in the sampling phase of its own terminal from the central processing unit, and a means for correcting the sampling timing of its own terminal. The central processing unit has means for receiving voltage and current data transmitted from each terminal device, means for calculating a branch point voltage for each terminal device from the voltage and current data transmitted from each terminal device, and It consists of means for calculating the phase shift between the voltage and current data of each terminal based on the branch point voltage calculated for each terminal data, and means for transmitting this phase shift to each terminal device.

(Function) In the present invention, the central processing unit calculates the branch point voltage from the voltage and current data of each terminal, calculates the phase difference between the branch point voltages obtained from the voltage and current data of each terminal, and calculates the phase difference between the branch point voltages obtained from the voltage and current data of each terminal. By transmitting the phase difference, that is, the deviation in sampling timing to each terminal device, and correcting this deviation in sampling timing at each terminal device, the sampling synchronization of each terminal can be adjusted.

(Example) Examples will be described below with reference to the drawings.

FIG. 1 is an example in which the sampling synchronization device according to the present invention is applied to a four-terminal power transmission line.

A four-terminal system will be explained below as an example.

The voltage and current at each terminal A to D of the power transmission line 1 are inputted to the data processing units 7a, 7b, 7c, and 7d of the terminal devices 6a, 6b, Gc, and 6d installed at each terminal, and are sent to the data transmitting unit 8a, 8b, 8c, 8d to transmission line 12a,
12b and 12c12d to the central processing unit 9. The central processing unit 9 receives the data of each terminal by the transmitter/receiver 10, and based on the data, the arithmetic unit 11 calculates the sampling phase shift of each terminal, and then the transmitter/receiver 10
Transmission from 112a, 12b, 12c, 12d
The sampling phase shift of each terminal is transmitted to each terminal device. Each terminal device corrects its own sampling timing by the amount of sampling deviation sent from the central processing unit.

In Figure 1, A, B, C, D are terminal names, Jl, , J
2 is the branch point, 1x is the line length of each section, and Zx is the impedance per unit length.

First, the outline of the present invention will be explained. In Figure 1, the branch point voltage ■J1 is expressed using the electrical quantity of the terminals involved in the branch point, and at the same time, ■J1-■a 'a za 'a
・・・・・・(1)V −V
! b 䋋b'bJ J1 b However, 1, V, 'Vb: Bus voltage I, Ib of each terminal
: Wire FI @ current of each terminal. , 2. Impedance per unit length between each terminal and the branch point f, 1: Distance b between each terminal and the branch point.

In other words, if the voltage and current at each terminal and the impedance up to the branch point are known, the synchronization of each terminal can be determined by using the fact that the branch point voltage obtained from the electrical quantity of each terminal is equal. By correcting the sampling timing of each terminal device to account for the synchronization difference, it is possible to synchronize the sampling of voltage and current data at each terminal. In the event of an accident between the terminal and the branch point, equation (1) no longer holds true, so sampling synchronization is always performed, and in the event of an accident, sampling synchronization control is performed.

In the 1121st, Af4A and B terminals are branch point voltage ■J1
Synchronization is achieved using the normal value of the C terminal and the own terminal, and synchronization is achieved using the normal value of the branch point voltage J2.

Normally, ＼P J1 and ■J2 are not in the same phase.v
-v -i no 1
- 1 ■ H1/≧Leak JI J2
There is the following relationship: e e e...(2). Therefore, 1° is calculated from the electric quantity of each terminal using the following formula.
, the phase shift between the data at the B end and the data at the C and D ends can be determined, and the mutual phase shift between all terminals can be determined. By transmitting the deviation of the sampling phase of each terminal from the reference value to each terminal, sampling 1 ring synchronization can be achieved at each terminal.

Next, the configuration and internal processing of the terminal device and central processing unit will be explained using the drawings.

FIG. 2 is a functional block diagram of the terminal device and central processing unit.

The voltage and current of the power system 101 are input to the terminal device 103 via the instrument transformer 102. The instantaneous value of this electric quantity is sampled at a fixed sampling timing in the data processing means 104 and converted into a digital quantity. The data converted into digital quantities is transmitted to the central processing unit 107 via the transmission means 105 at regular intervals.

The central processing unit 107 receives data from each terminal device 103 via the transmission means 108, calculates sampling synchronization between each terminal device in the calculation means 109,
The deviation is transmitted to each terminal device 103. In the terminal device, the sampling timing of the own station is corrected by the sampling synchronization control means 10G based on the deviation value from the central processing unit.

By synchronizing the sampling of each terminal device, this device can be applied to failure point locating devices, oscilloscopes, etc.

For example, when an accident occurs on a power transmission line, the failure point locating device 110 receives voltage and current data from each terminal device 103 via the transmission device 108, and locates the failure point using the following formula. In the system shown in Fig. 1, [phase] (b) c) Fig. 3 is a flowchart for calculating the sampling timing deviation of each terminal, and using this, the central processing unit performs arithmetic processing of sampling timing deviation. Explain.

In step 5201, the branch point voltage seen from each terminal is determined.

In Figure 1, the voltage at branch point J1 seen from A@ is ■Ja=■
a 'a, 18 The voltage at branch point J2 seen from the B end is - and -1b, b'b Jb b Since the sampling of each terminal is not synchronized, the voltage at branch point J2 is
The phases of "Jlb" and "Jlb are out of sync. Therefore, the step 5202 uses the branch point voltage to find the phase difference due to the out-of-synchronization of the A end and the B end.

The voltage at the branch point J1 seen from the A end at the sampling time m is ■ - (■ -2a 'a ) n Jan a ■ JaS1nθ The branch point voltage seen from the A @ at the sampling time n is v - (v - no blb ) .

Jbn b ■JbIS1n (θ+φ) Here, φ is a phase difference due to loss of synchronization.

This φ can be found as follows.

For example, if the sampling interval is 30°.

V -V-V Jan Jbn-3Jam-3vJbn-) Stand]
S1nθl v , 1bl s+n(θ+φ−904)
Ja v Ja l sin (θ-90') l
VJbl 5in(θ+φ)v 1sinθ1MJb
lCO8(θ1φ)Ja +1■ 1CO3θl v Jbl 5in(θ+φ)
Ja −−l v l l vJbl 51n(θ−θ−φ
) Ja vJal l vB, l sinφ...
...(9) vJam-vJbn+■JaI11-3■
Jbn-3■ l51nθl v Jbl 5in(θ
10φ) Ja ■J8: S with θ-90°) Dimension Jb1S1n (θ10φ-90°) ■ 1 sin θl V Jbl 5in (θ10φ) Ja +) MJaICO3θl V Jbl C03 (θ+φ
) size, Ja j j ■Jb: CO3(θ-θ-φ
) = i v J, i l vJbl cosφ
・・・・・・(10)(9),(10)
From the formula vv-vv Jall Jbn Jalm-3Jbn-
3...(11) becomes.

In step 5203, the phase of the current at the B end is corrected by the amount of synchronization between the A end and the B end. For example, if the sampling timing of A@ is used as the reference, the current data at the B end is delayed by the phase angle φ and corrected before correction after correction...
・Do as shown in (12).

In step 5204, the phase difference due to the out-of-synchronization between the C end and the D end is determined in the same manner as in step 5202.

The voltage at the branch point J2 seen from the C end at the sampling time m is . □=(stand.-之.io)□ sunJ. l sinθ (13) The voltage at the branch point J2 seen from Df4 at the sampling point is ■Jdn ” ”d −26'd 'n= i v J
dl sin (θ+φ')...(14) The phase difference φ' due to synchronization is (9), Tl0),
It is calculated using the same calculation as in equation (11).

In step 5205, as in equation (12), current data at the D end is corrected and delayed by the phase angle φ' with respect to the C end.

In step 8206, the B-terminal current is synchronized with the A-terminal φ
Using the height-corrected data, J
, J2.

In step 5207, D@main current C@which synchronization difference φ'
Using the corrected data,! =! Find the current between J and J2 using the formula +ldC.

Due to the synchronization between the A end and the C end, i = iie 1 sinω↑ e ... (15) 1
−l ie l Sin (ω1+φ).

By determining the synchronization difference φ between 1 and 18, the phase difference due to mutual synchronization of the A end, B end, C end, and D end can finally be found.

In step 8208, (9), (10), (11
Similar to formula 1, 1-I era en-3et++-3'en=l Ie
l l Ie l sinφ″II+II em en em-3en-3=l io l
l io 1cosφ'' (16) φ'' is found as follows. Step 5209 Af4
The sampling phase shifts between the A and B ends, C ends, and D ends are determined as follows.

With the A end as a reference, the phase shifts of the data at the B, C, and D ends are B@: delayed by φ, C end: delayed by φ', and D end: delayed by φ'+φ'.

Then, the central processing unit 107 transmits the phase shift of the data of each terminal to each terminal device 103.

A@ terminal device: transmits orad Terminal device at the end; transmits φ ad CtlA terminal device: Transmit φ′ ad The terminal device at its own end; φ′+φ″rad is assumed to be the transmission.

In the above embodiment, the voltage and current data was transmitted from the terminal device to the central processing unit at regular intervals, but in another embodiment, the central processing unit outputs data transmission request pulses to each terminal device simultaneously, and each terminal Next, an example of transmitting voltage and current data to the central processing unit after receiving and receiving pulses will be explained using the drawings.

FIG. 4 shows the processing flow of the central processing unit. Step 5
301 is the transmission delay time T between each end and the central processing unit.
, is measured for each terminal. In step 5302, T is transmitted to each terminal. In step 5303, data transmission request pulses are simultaneously output to each terminal.

FIG. 5 shows the flow of processing of the terminal device. Step 540
1 receives the transmission delay time between the central processing unit and the corner of the eye; Step 5402 receives and receives a data transmission request pulse. In step 5403, the voltage and current data from the time when the pulse is received to the time before the transmission delay time Td is transmitted to the central processing unit.

A method for measuring the transmission delay time T in step 5301 is shown in FIG.

A flag is transmitted from the central processing unit to each terminal device. When the terminal device receives the flag from the central processing unit,
After T hours, the receiver transmits a receipt confirmation flag to the central processing unit. The central processing unit measures the time T from when the flag is transmitted to each terminal until the flag is received from each terminal. Since the round-trip transmission delay time between the central processing unit and the terminal device is almost equal, the transmission delay time is Td=
(T-To)x is calculated.

FIG. 7 is a block diagram of another embodiment.

In this embodiment, the functions of the central processing unit are included in the terminal device at the A end and used as the main device.

In the figure, 501 is a power transmission line, 502, 503.50
4.

505 is an electric station. Terminal device 5 installed at each terminal
Data processing unit 511 of 10b, 510c, 510d
b, 511c, 511d, and transmits it to the clay W506 from the transmitting/receiving sections 512b, 512c, 512d of the terminal device via transmission lines 513b, 513c, 513d. Earthen fi506 is the transmitter/receiver part 50
9 receives data from each terminal device, and inputs the voltage and current data of its own terminal from the data processing unit 507, and calculates the deviation of the sampling synchronization of each terminal from the sampling phase itself in the calculation unit 508. The transmission/reception unit 509 transmits the sampling phase shift of each terminal obtained here to transmission lines 513b, 513c, 513 to each terminal device.
It is transmitted via d.

[Effects of the Invention] As explained above, according to the present invention, the branch voltage is obtained using the voltage and current obtained at each terminal, and based on the sampling synchronization shift of each terminal calculated using this, By correcting the sampling timing at each terminal, it is possible to synchronize the sampling at each terminal, which requires a special large-capacity transmission line.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the sampling synchronization device according to the present invention, FIG. 2 is a functional block diagram of the terminal device and central processing unit of the present invention, and FIG. 3 is a flowchart for calculating the deviation in sampling timing of each terminal. , FIG. 4 is a flowchart showing another example of data transmission processing by a terminal device, FIG. 5 is a flowchart showing another example of data transmission processing by a central processing unit, and FIG. 6 is an explanation of a method for measuring transmission delay time. 7 are block diagrams of other embodiments of the sampling synchronization device according to the present invention. 1...Power transmission line 2-5...Electric station 6...
・Terminal device 7...Data processing unit 8...Data transmission unit 9...Central processing unit 10...Transmission/reception unit 11...Calculation unit 12...Transmission path patent applicant Toshiba Corporation Agent Nori Ishii, a patent attorney.

Claims (1)

[Claims] A sampling synchronizer for a power system protection and control system that synchronizes the sampling of voltage and current data at each terminal of a multi-terminal power transmission line includes a means for sampling and inputting terminal voltage and current at a constant cycle, and a means for inputting the voltage and current data at a fixed period. A terminal device comprising a means for transmitting to a central processing unit, a means for receiving sampling phase deviation of its own terminal from the central processing unit, and a means for correcting sampling timing of its own terminal, and receiving voltage and current data from the terminal device. means for calculating the branch point voltage for each terminal device from the voltage and current data transmitted from each terminal device; and a means for calculating the voltage of each terminal, based on the branch point voltage calculated for each terminal data. A sampling synchronization device characterized by comprising a central processing unit comprising means for calculating a phase shift between current data and means for transmitting this phase shift to each terminal device.