RU1807426C - Method of determination of distance to point of fault in power line and device for its implementation - Google Patents

Abstract

The invention relates to electrical engineering and can be used to determine the distance to a short circuit (SC) on power lines. The essence of the invention lies in the fact that timing complex signals are sent periodically from one end of the serviced line to the opposite end, ensuring that the timing at both ends of the line is in phase, the moments of arrival of the fronts of the electromagnetic wave that occurs during short-circuit are recorded, and the front is fixed only when exceeding the last constantly monitored interference level. A fixed time of arrival of the wave front is transmitted to the opposite end of the line using the same timing complex signals, which in this case are perceived as informational. The calculation of the distance is carried out in accordance with the expression At v / 2- (Tc + T -n) -v / 2, where I is the distance to the fault from the end of the line from which the timing signals are sent; v is the propagation velocity along the line of electromagnetic waves and signals; TC is the duration of the complex signal; At is the duration, the duration of the time interval, which determines the difference between the recorded periods, the time of arrival of the wave fronts, taking into account the time taken for setting the reference moments and for transmitting and receiving information signals. A device that implements the method consists of a leading half-set installed at the far end of the line, and a driven half-set installed at the near end of the line. The leading half-set consists of a quartz reference frequency generator, a cyclic time counter, a low level limiter, a front receiver, a complex signal former, a power amplifier, an OR element, and an RF connection unit. The slave half-set consists of a quartz reference frequency generator, a low-level limiter, a front receiver, an RF connection unit, a line receiver, a matched filter unit, a signal arrival time counter, a far end time counter, a line status monitoring unit, a key, a calculation unit and a memory tee, own time counter. The matched filter block consists of p matched filters, a binary quantization block, a counter, a decoder, p counted triggers, and a decision block. 2 sec and 1 C.p. f-s, 4 ill. ate s so o o 2 ke o

Description

The invention relates to electrical engineering and can be used to determine the distance to the point of damage to power lines during short circuits.

The aim of the invention is to increase the reliability, reliability of determining the distance to the place of damage, as well as increasing electromagnetic compatibility with devices using the same communication channels.

Fig. 1 is a block diagram of a leading half-set of a fault locator (WMD) installed at the distant non-serviced end of the line (i.e., the end where no intervention by operational staff is required to acknowledge and read the readings); figure 2 is a structural diagram of the slave half of the device WMD installed on the near, served end of the line; Fig. 3 is a timing diagram of the operation of an OMP device that implements the proposed method, where T is the repetition time of the sending of timing signals, to is the instant of occurrence of a short circuit, tcur. - duration of the composite signal, tpacnp.1 - propagation time of the front of the electromagnetic wave to the transmitting semi-intelligence, tp.c. is the propagation time of the signal from the transmitting to the receiving half-intellect, ti is the time of installation and counting of the counter of the receiving end, tpacnp.2 is the propagation time of the electromagnetic wave front to the receiving half-intellect, tc.co6. - period counted by the time counter, the arrival of the front to the receiving (slave) half-intellect, tnonn. - a complete data acquisition unit from the opposite end of the line until all the counters at the receiving end of the line are reset to zero, 1 count.2 - the period counted by the time counter of the opposite end; figure 4 is a block diagram of a block of matched filters,

The WMD device consists of a leading half-set installed at the far end, a line and containing a reference frequency crystal oscillator 1, a controlled time counter 2, a low level limiter 3, a front locking unit A, an RF connection unit 5, an OR element 6, a generator 7 timing pulses, including a signal shaper 8 and an amplifier 9, and a slave half-set installed at the near end of the line and containing a linear receiver 10, a matched filter block 11, a signal arrival time fixing block 12, a time counter 13 zli

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the end thereof, the calculating and memory unit 14, the line state monitoring unit 15, the key 16, as well as the reference frequency crystal oscillator 1 included in the master half-set, a controlled time counter 2, a lower level limiter 3, a front fixing unit 4, block 5 RF connection.

Block 11 matched filters (figure 4) consists of identical nodes 17, made according to the known scheme and connected with respect to the first signal input in parallel, the combined signal input is connected to the output of the receiver 10 through the input block 22. Clock signals coming to the clock inputs of matched filters are formed by a counter 18, a decoder 19 and triggers 20. The outputs of matched filters are connected to the corresponding inputs of the decision block 21.

The device operates as follows.

Leading half set

25 at one end of the line (with one-way power on radial and stub lines from the side opposite to the supply end of the line), it is connected to one of the phases of the monitored line equipped with the RF connection system 5. The slave half-set is installed at the opposite end of the line and connected to one of the selected phases of the line (not necessarily the same phase) through a similar high-frequency RF connection system. Both installed half-sets are synchronized from the individual quartz oscillator 1 with the same frequency. Moreover, the highly stable crystal oscillator 1 generates continuous oscillations with a period that is a multiple of the travel time of an electromagnetic wave of one kilometer of the line. On the leading half-set, the reference frequency of the crystal oscillator is fed to counter 2. This counter is periodically set at zero reference every time overflow through the OR 6 element. When the counter is set to zero, either as a result of overflow, or forcibly when a reset signal is received at its second input by a pulse, a circuit for generating a complex radio pulse signal, for example, a radio pulse amplitude-manipulated M-sequence, is launched from the counter output. Thus, through the OR element 6, it is reset to zero. counter 2, providing a predetermined chicanity of repetition when transmitting signals inferior as timing, or

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the reference point is fixed, and then the transmitted signals become simultaneously informational, ensuring the transmission of the moment of arrival of the front of the electromagnetic wave.

The clock frequency of the pulse and sequence is a multiple of the frequency of the crystal oscillator. The complex signal generated in block 8 through the power amplifier 9 and the RF connection system 5 is supplied to the line and propagated to the opposite end of the line.

When a short circuit occurs (time to in Fig. 3) on the monitored line, the front of the electromagnetic wave propagates from the short circuit to both ends of the line. Having reached the leading end of the line after a time equal to l / v (where I is the distance from the short circuit point to the installation site of the leading half-set), it passes through the RF connection system 5 and, if the amplitude of this wave exceeds the level of the concentrated interference (these include their own timing signals, RF signals of relay protection, automation, etc.), the wavefront through the OR 6 element sets the counter to the zero position, which at this point in time issues a resolution signal to 8 to form the composite signal.

Thus, by sending this timing signal, the time tcn.1 (Fig. H) is counted, counted down by the counter from the moment of initial setting to the reference position, and a new moment is set to start the reference of the next counter filling cycle.

Front of wave propagating to. the near end, on which the slave half-set is installed, after a time determined by the dec. 2 L / vl / v (L is the total line length), is fed to the input of the 5 RF connection system and then, it went through processing in blocks 3, 4 , similar to the blocks of the transmitting half-set of the same name, stops the counting of clock pulses on the counter 2, at the same time this signal is recorded by the line state monitoring unit 15.

Previously (until a short-circuit occurs), the timing signals, reaching the opposite end of the line, pass through the RF connection unit 5 by linear filtering and detection in the linear receiver 10, after which the envelope sequence is fed to the input of the matched filter unit 11, where in the input block 22 performs its binary quantization to form a video pulse sequence.

This sequence is fed to the inputs R of the matched filters. Each 5 of these filters processes the received sequence (time compression and comparison with the set threshold levels).

Each matched filter at its own output forms a response to the received signal, V times shorter than the full duration (Tsign.) Of the complex signal (B is the base of the complex signal, V D f -tcum .; Af- the effective frequency band is received - 5th signal, depending on the bandwidth of the path, including the RF path through the overhead line (VL) and the line receiver of the slave half-set). For the received complex waveform 0 (M-sequence), the response of each of the matched filters is a pulse whose duration is equal to the sampling period (T0).

The matched filter is invariant to

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the time of arrival of the signal within the period (To) of the main clock frequency, which determines the time of a single element of the incoming timing signal. At the same time, matched filters, clock

0 whose frequency within the period T0 is phase shifted relative to each other by discrete segments T0 / 2K. constituent part of the time of a single signal element can fulfill the functions of a correlator 5 and even for these discrete smaller time elements the invariance condition is violated. Therefore, the result of the correlation of the incoming signal with the expected one in each of these filters will be different, reaching a maximum for filters in which the signal arrival time coincides with the phase of the clock pulses up to a time interval equal to To / 2 K.

5 Each of the matched filters included in block (11) includes (Fig. 4) a shift register (PG), the first adder connected to the taps of the shift register triggers located mirror 0 with respect to the burst pulses of the received complex signal , the second adder, the inputs of which are connected to all PG taps, with the exception of those connected to the first adder,

5 decision block (BR) and voltage converter (Pr). The principle of operation of such a matched filter is that at each cycle of the pulse repetition rate (To), the sum

of the received burst pulses, experimentally (blocks of the second adder and Pr), the probability of false reception corresponding to the current during tcm-n is calculated. interference, the required threshold voltage is generated inertialessly in the BR unit based on the calculated probability of false reception and, based on the comparison results, a decision is made to receive a complex signal, which manifests itself as the appearance of a video pulse of duration T0. Since all operations are performed at each cycle, the reception is carried out by the filter without searching for the position of the signal in time.

In order to provide an increased resolution of fixing the moment of reception (s) of the incoming signal, matched filters relative to the input signal are connected in parallel, and the clock pulses supplied to these blocks are interconnected by a functional relationship, so that the initial phases of the clock signal during the duration of the clock pulse formed using the counter 18, the decoder 19, the counting trigger 20, are discretely offset relative to each other. The magnitude of this offset will be determined as To / 2 K, where K is the number of filters connected in parallel,

In the absence of phase synchronization of the clock pulses of the shaper 8 of the complex signal of the master half-set and the clock generators of the matched filters of the slave half-set, the resulting voltage at the output of the threshold block (21), which characterizes the result of the signal compression operation, exceeds the set threshold only for p from the installed filters. Therefore, in the block 12 of fixing the moment of arrival of the signal to provide a more accurate fixation of the moments ti, the moment of exceeding the threshold for the first of p filters is noted and at the same time as the signal of the start of the time counter, supplied through the key 16 to the counter 2 of the proper time, the number 2k-2 . This number characterizes the amount of delay time compensation associated with limiting the bandwidth of the propagation path of the complex signal.

At the same time, the signals from the output of block 11 passing through the key 1 b establish the reference point in the counter 13 of the far end time. Thus, the signal from the output of block 12 is the start signal for starting counting of both counters 2 and 13, characterizing the time ti of the time diagram of FIG.

In the absence of damage, after a T-constant repetition period of sending timing pulses, both counters are simultaneously set to their initial position and begin counting clock pulses arriving constantly at their inputs from the crystal oscillator 1 of the clock frequency.

With a short circuit, the wave front,

extending to the proximal end, on which the slave half-set is mounted, after a time defined as L / v-l / v (L is the total length of the line), is fed to the input of the RF connection unit 5. After processing in blocks 3 and 4, the wavefront stops the count of clock pulses on the counter 2 of the proper time, at the same time this signal is detected by the line state monitoring unit 15.

If any reasons, in particular, an increase in the excessively calculated attenuation of the propagation path of the complex signal caused by line damage or the high level of interference from the short-circuit arc, does not allow the complex signal to be received and the time of its arrival is recorded accordingly, the far-end time counter 13 continues to count . The first complex wave after the passage of the wave front, received and fixed by block 12, provides the appearance on the first output of block 15 of the state of the control signal line of the operation control signal of calculation and memory unit 14. Last

records meter readings and performs calculations with the indication of the distance to the fault location.

The calculation of the distance in block 14 is carried out in accordance with the formula

  Arv / 2- (TcHrH + T n) -v / 2.

where At is the difference between the recorded values of the counters; Tsign. - the duration of the complex

signal; n is the number of whole repetition periods of sending timing complex signals to the first received after fixing the front of the wave propagating from the place of the short circuit.

The initial installation of counters 2 and 13, preparation for receiving new information in the memory unit 14 and the calculation is carried out by the line state monitoring unit 15. This operation is carried out under the condition that the line is switched back on, when the signal from the device for switching back on is supplied to block 15 and a key control signal 16 is generated at its second output, which exists until the signal arrives

about the reception of the wave front. As a result, the timing signal coming from the master half-set sets the counters 2 and 13 to the initial state and the monitoring process continues. 5

The implementation of the RF attachment units 5 is known. The majority of overhead transmission lines with voltage of 110 kV and higher are equipped with such blocks, therefore, these blocks can be used when installing the device on active lines with the established organization of a system of RF channels over the overhead lines.

The limiter (3) of the lower level can be performed, for example, on the basis of a controlled key that passes only signals of a level that exceeds the previously fixed level of concentrated interference (narrow-band sinusoidal signals of its transmitter, 20 communication systems, relay protection and etc. equipment using the same communication channels over the OHL wires). The fixed level is continuously compared with the incoming signals on a comparator, the output signal of which controls the key. The line state monitoring unit (15) can be made on the basis of logic elements switching clock pulses and counter control signals and the calculation and memory unit 30 depending on the presence (logical unit level) or absent (logical level zero) of the signal from the automatic reclosure device .

The calculation and memory unit (14) controlled by 35 counters 2, 13 can be constructed according to well-known principles on the basis of integrated circuits of the K155, KP580 and KP589 series.

The unit 40 for detecting the moment of arrival of the signal 40 la serves to normalize the control pulse by the moment a signal appears at the output of the matched filter and can be implemented as a standby multivibrator, for example, based on the K155AGZ microcircuit. Linear receiver 10 combines a detector of radio pulse signals and input and output analog amplifiers based on K154UDZ analog microcircuits. Block 4 of the front fixing can be performed on the basis of the standby multivibrator (K155AGZ chip), which is triggered by the leading edge of the incoming signal.

The standard implementation of the crystal oscillator 1, key 16, counters 18, de 55 Encoders 19, triggers 20, input unit 22 is known from literary sources. The execution of decision block 21 may be implemented as a comparator-based actuation circuit.

The circuit of the signal shaper 8 is made in accordance with the circuit diagrams given in the known literature.

Using the proposed method for determining the distance to the place of damage and the device for its implementation, in comparison with the existing methods, it is possible to increase the reliability, reliability of determining the place of damage, electromagnetic compatibility, which, ultimately, reduces the time to search for the place of damage and interruptions in the power supply of industrial enterprises enterprises and settlements, and also allows you to install and operate these devices in conjunction with other communication systems, automation and relay protection Ita without causing interference with the latter and using slozhivshies acting RF communication channels over the wire overhead line, to improve the reliability and validity when receiving Timing and data signals under conditions limited transmission channel bandwidth.

Claims (3)

The claims 1. The method of determining the distance to the place of damage on the transmission lines, which consists in the fact that periodically send timing pulses transmitted from one end of the (leading) serviced line to the other end (slaves), set reference points in time to ensure the phase readout time at both ends of the power line arising at the time of short circuit electromagnetic waves are fixed at both ends of the line, characterized in that that, in order to increase the reliability, reliability of determining the location of damage and electromagnetic compatibility at each reference point in time, complex complex radio signals are sent as timing pulses, the front of the electromagnetic wave is fixed at both ends of the line when the latter exceeds the level set automatically depending on the level of concentrated interference, at the moment of fixing the front of the electromagnetic wave at the leading end of the line, the generated timing signal is transmitted against the lower slave end of the line, where after the moment of fixing the wave front, coming from the place of the short circuit, the signal is perceived as informational, the moment of the termination of the perception of this complex signal as informational is judged by the state of the line, it is perceived as timing for a subsequent cycle of control when the line is switched back on, and the distance to the place of damage is determined by the formula I At -y / 2- (Tsign. + T-n) -v / 2. where I is the distance to the place of damage from the end of the line from which the timing signals are sent; v is the propagation velocity along the electromagnetic wave line; n is the number of whole repetition periods for sending timing complex signals to the first received after fixing the front of the wave propagating from the place of the short circuit; T is the repetition period of sending timing signals; Tsign. - the duration of the timing complex signal; At is the duration of the time interval obtained as the difference of two recorded periods, the beginning of which is determined by the time of arrival of the timing signal, and the end for one moment the front arrives at the slave end, for the other - the moment of confident reception of the first of the n timing signals that arrived at the driven end after fixing on it a wave front from the place of damage. 2. A device for determining the distance to the place of damage on power lines, containing two half-sets - master and slave, installed at opposite ends of the line, and the leading half-set contains a block for fixing the front of the electromagnetic wave, a controlled time counter, a pulse timing generator srv, the slave half-set contains a block for fixing the front of the electromagnetic wave, a controllable counter and a linear receiver of timing pulses, characterized in that the leading half-set is additionally sleep It is equipped with a block for lowering the level of the front of the electromagnetic wave, a quartz oscillator of the reference frequency, an OR element, a block of high-frequency connection (VP), and a timing pulse generator consists of a series-connected block for generating a complex signal and an amplifier connected to the line through a block of high-frequency frequency connection, at the same time, the input of the low-frequency blocking unit is connected to the input of the lower level limiting block, which is connected to the first input of the OR element through the block of the front fixing, output the counter is connected in parallel to the second input of the OR element and to the first input of the complex signal driver, the output of the OR element is connected to the installation input of the counter, the quartz reference frequency generator is connected to the clock input of the counter and to the second input of the complex signal generator, the slave half-set is additionally equipped with a lower level limiter, a quartz reference frequency generator, an RF connection unit, a matched filter unit, a unit for fixing the moment of arrival of a complex signal, a time counter its end, the line status monitoring unit, the key, the memory and calculation unit, while the output of the RF connection unit is connected to the inputs of the lower level restriction blocks and the line receiver, the output of the restriction block via the edge fixing block is connected to the first control input of the self counter time and the third input of the line state monitoring unit, the output receiver is connected to the signal input of the matched filter unit, the output of which is connected to the first the first control input of the far-end time counter, the first key input and the fourth input of the line state control unit, to the first input of which a signal from the automatic reclosure device is supplied, the first output of the line state control unit is connected to the control input of the calculation and memory unit, and the second output is to the control input of the key, the first output of which is connected to the second control input of the counter of own time, and the second output of the key is connected to the second control input of the counter of the time of the far end, the output of quartz g the generator is connected to the clock and clock inputs of the own time counters and the far end time counter, the matched filter block, the line status control unit, the output information buses of the own time and far end time counters are connected to the information inputs of the calculation and memory unit. 3. The device according to claim 2, characterized in that for improving the accuracy and resolution when fixing the moment of reception of a complex signal under conditions of limiting the frequency band of the transmission channel, the matched filter block contains K identical matched filters for detecting and recognizing a video pulse sequence , an input unit that performs binary quantization of the detected signal from a linear receiver, a counter, a descrambler, K countable triggers, a decision block that produces threshold and the choice of the maximum values of the cross-correlation function generated by the matched filters, the signal from the line receiver from the output of the input unit is connected to the signal inputs of all K matched filters, the pulses from the clock generator are fed to the counting input of the counter, the outputs of which are connected to the inputs of the decoder , each of the K outputs of the decoder is connected via a trigger to the clock input of a matched filter, the outputs of matched filters are connected to the corresponding inputs of a block ti decisions output of this block is output all matched filter unit. 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