JPH0156386B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a return signal transmission method in a B-type fault locator.

In the conventional B-type fault locator, in order to transmit the surge reception status at the slave station to the master station, the return pulse is transmitted as one piece of data through multiple digital transmission paths. In this case, the data will be encoded and transmitted by multi-point sampling as shown in FIG.

In the figure, a indicates a received surge, b indicates a surge detection pulse, c indicates a sampling pulse, and d indicates a return pulse.

That is, when a surge as shown in figure a is received, a surge detection pulse as shown in figure b is output.

This is sampled by the sampling pulse shown in figure c to generate the return signal shown in figure d.

However, in this case, sampling distortion (Ts
Therefore, in order to accurately transmit the pulse rising point, it is necessary to increase the sampling frequency and use a high-speed channel (equivalent to a wide band).

Currently, if sampling distortion is to be within ±1 μs of gauge error, sampling at 500 KHz is required, which is not realistic.

The present invention was made in view of these points,
The purpose of this method is to remove sampling distortion during sampling of surge detection points and to easily transmit surge detection points with high accuracy over a low-speed digital line.

The present invention will be explained below based on examples.

Figure 2 is a block diagram of the present invention, and in the figure
OSC is a reference oscillator, COT is a counter, FG is a frame generator, CG is a clock generator, T is a timing extraction circuit, CC is a sign verification circuit, T is a delay circuit, and CA is an arithmetic circuit.

To explain the operation, before the output of the surge detector appears on terminals 1 and 2, the frame generator FG uses the clock from the clock generator CG to achieve phase synchronization with the receiving side (master station). , a unique pattern like 1/12 pattern (000000000001) is sent.

On the other hand, on the receiving side, the timing extractor T detects this pattern and synchronizes.

The timing at this time is as shown in Figure 3.

In the figure, a indicates a sampling clock on the transmitting side, and b indicates a sampling clock on the receiving side.

As shown in the figure, the transmission delay time between the sending side and the receiving side is
Only TD's timing is off.

This td is a value that can be known in advance.

When the surge detector detects a surge as shown in FIG. 4A, an output shown in FIG. 4B is input to terminal 1. This output causes the counter COT to start counting pulses from the reference oscillator OSC as shown in Figure d, and stops counting in response to the next sampling pulse from the clock generator CG.

Let ts be the time of this count.

Note that diagram c is a sampling clock.

The counter COT holds the count value during ts as binary data D. Also frame generator
The FG interrupts the transmission of the synchronization signal by the output of the surge detector, generates and transmits a code string having a frame structure as shown in FIG. 5.

Here, ST is a start bit, which is a signal to be distinguished from a synchronization signal. (“110” as an example) D is the aforementioned binary data,
C is a code for data verification. (Parity or cyclic code, etc.) SP is a stop bit and indicates that a series of code strings has ended. (One example is "00") When the transmission of the above code string is completed, the frame generator FG resets the counter COT and returns to the initial state to wait for a surge.

On the receiving side, the start bit is set by the code string validator C.
When ST is detected, it is determined that it is surge information,
The following code string is verified, and if there is no error, data D is extracted, and the arithmetic circuit CA calculates the time relationship with the own station's surge signal input via the delay circuit T, thereby locating the fault point. The timing relationship at this time is as shown in FIG. 6, and the surge detection point t _r on the transmitting side can be known as t _r =t _d +t _s .

In Fig. 6, a is the surge detection output on the transmitting side;
b indicates a sampling clock on the transmitting side, c indicates transmitted data, and d indicates received data.

As explained above, by sending the amount of sampling distortion at the time of sampling the surge detection point to the other party as a digital amount, the operating point can be accurately transmitted even on a low-speed digital line, and the positioning Accuracy can be determined by the counter clock frequency and can be independent of the transmission rate.

[Brief explanation of drawings]

Figure 1 is a diagram for explaining sampling distortion.
Fig. 2 is a block diagram of the present invention, Fig. 3 is a diagram showing the phase relationship between the sampling clocks on the transmitting side and the receiving side, Fig. 4 is a diagram showing the operation of the present invention, and Fig. 5 is a diagram showing the sending to the receiving side. FIG. 6 is a diagram illustrating the operation of the arithmetic circuit. In the figure, OSC is the reference oscillator, COT is the counter, and FG
is a frame generator, CG is a clock generator, T is a timing extraction circuit, C is a sign verification circuit, and T is a delay circuit.

Claims (1)

[Claims] 1 A master station device is installed at one power station of a power transmission line, and a slave station device is installed at the other power station, and the surge that occurs during a power transmission line accident is received at both ends, and the fault point is calculated based on the difference in arrival time at both ends B. A return signal transmission system for a fault locator is characterized in that a code string indicating the time from when a surge is input to the first phase synchronization signal is synchronized with the phase synchronization signal and transmitted as a return signal. Return signal transmission method for B-type fault locator.