DE1069761B - Circuit arrangement for monitoring the transmission properties of a high-voltage line - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

PATENT LETTER 1069761

INTERNATIONAL KL.

HOIh; H 02h

REGISTRATION DATE: 7. A PRI L 1959

NOTICE
THE REGISTRATION
AND ISSUE OF
EDITORIAL: NOVEMBER 26, 1959

ISSUE OF

PATENT FILING: APRIL 28, 1966

DEVIORS FROM EXPLOITATION

(S 62469 VIIIb / 21c)

The invention relates to a circuit arrangement for monitoring the transmission properties a high voltage line. Such monitoring is carried out by comparing the current phases accomplished at both ends of the line with each other that when a certain phase difference between the two currents, the transmission line is switched off. Here is based on the known fact that in the event of a fault on the high-voltage line, z. B. by earth fault or by arc caused by a lightning strike, the leaps and bounds Change the phase angle of the alternating current at both ends of the line. In the event of a fault, the current vector rushes opposite the current vector on an undisturbed line at one end of the line, while chasing after the other. Then and only if the phase jumps differ in terms of Size or direction, the line may be switched off, as in this case an error occurred on the line.

A monitoring method is known in which the flow of energy at both ends of the line is monitored and in which the line is switched off if both Line ends it is determined that energy flows into the line. This comparison procedure will carried out with a so-called direction comparison protection. This comparison protection consists of Relay devices at each end of the line, with those from the voltage vector, its continuous Direction of rotation does not change in the event of a fault on the line compared to the undisturbed line, and the current vector, the direction of the short-circuit current is determined. A comparison with the measurement result of the apparatus at the opposite end of the line indicates whether the line has been switched off may or may not be.

Since in this case the direction of the short-circuit current is determined from the current and voltage vector must be, both current and voltage transformers are required at each end of the line. Since these are generally high operating voltages, the voltage converters are very expensive, d. that is, all of the comparison protection is expensive. For exchanging the measurement results on both However, only a very simple transmission channel needs to be made available since yes, from one end to the other it is only necessary to report whether energy is flowing into the line or flows out of the line ("yes-no" transmission).

Circuit arrangement for monitoring

the transmission properties of a

High voltage line

Patented for:

Siemens & Halske Aktiengesellschaft,
Berlin and Munich

Gerhard Bergmann, Munich,
has been named as the inventor

In another known method, the phase angles of the line current at the ends the high-voltage line compared directly with each other. For this, of course, the one at one end has to be current fed in or withdrawn from this end, d. H. its phase, in phase with the the other end of the line so that a comparison of the two phases can be carried out can. For this purpose, a high quality transmission channel must be made available, since the The content of the message to be transmitted is large. There must be a measurable variable, namely the phase angle, are constantly transmitted, which is especially true for carrier frequency or radio links with the The required accuracy is very difficult, since a broad transmission band, which is often not available, is available for this purpose is necessary and forgeries caused by interference voltages can hardly be avoided.

The phase comparison protection device explained last has the advantage that only the Size and phase of the current must be determined at both ends of the line, including only one Current transformer is necessary. There is no need to arrange an expensive voltage converter.

The circuit arrangement for monitoring the transmission properties of a high-voltage line according to the invention combines the advantages of both methods. Even with the circuit arrangement according to the invention, as in the previously known arrangement described above, a comparison is made of the current phases carried out at both ends of the line, whereby when a certain value is exceeded Phase difference the transmission line is switched off. In the circuit arrangement according to the invention is also no

609 563/584

Voltage converter required. But it is also used for the transmission of the current phases, in modification of known designs, no broadband, d. H. more expensive transmission channel required. An effective one Current comparison between both ends showing the transmission of a phase of current from one end to the other end, is achieved according to the invention that at each end of the high-voltage line Switching means for determining the phase jumps of the fed into the line or from the line drawn current are provided, the occurrence of phase jumps with respect to determine the size and direction and the occurrence of phase jumps via a transmission system in a coded form, e.g. B. in the form of rectangle changes, communicate and thus the on the other end of the comparison and triggering device, the direction and size of the phase jump display for evaluation via a relatively narrow-band transmission channel.

In the circuit arrangement according to the invention, therefore, is immediately at each end of the line a phase jump detected and only the transmission of a phase jump with indication of the direction communicated to the other end of the line. The transmission line is then from the network and only switched off when the phase jumps that have occurred are a certain minimum size and in particular have different directions.

For the local determination of phase jumps at the two line ends, according to a further development Proposed of the inventive concept to provide a generator in each case, which has a The delay element is drawn from the high-voltage current when the network is undisturbed and its output voltage fed together with a directly applied voltage derived from the line current to a phase comparison device known per se will. This training ensures that sudden phase jumps in a disturbed network the pull-along generator continues to oscillate in its original phase position, so that the phase comparison device the phase of the generator together with one derived from the line current, one Phase jump containing voltage is compared. Depending on the evaluation of the phase comparison device a signal is then triggered that is communicated to the other end of the line or with a Message is compared by the other phase comparison device, then depending on this comparison result the high-voltage line is switched off.

The circuit arrangement according to the invention is illustrated below with reference to a few exemplary embodiments explained. Here, the mode of operation is first shown using a block diagram as shown in FIG. 1 is reproduced.

FIG. 2 shows current diagrams for the exemplary embodiment according to FIG. 1. In the circuit configuration according to FIG. 1, an alternating voltage proportional to the line current with a curve α (FIG. 2) is fed to point A , namely to limiter 1. At the feed point an exciter relay 4 is also arranged, which always responds when the supplied current exceeds a predetermined maximum limit.

The AC voltage supplied is practically limited to square wave changes in the limiter 1 (line b in FIG. 2). The AC voltage limited in this way is then superimposed on the output voltage of a pull-in generator 6 via a low-pass filter 2 and a delay network 3 via the contact k 4 of the excitation relay 4. The amplitude of the fluctuation occurring at the output of the generator 6 (line d in FIG. 2) depends on the phase angle difference between the output voltage of the delay network 3 (see line c in FIG. 2) and the output voltage of the generator 6 (see line d in FIG Fig. 2). This output voltage is rectified in the rectifier 5 and serves as a control voltage for the pull-along generator. This changes the frequency of its output voltage as a function of this control voltage until it equals the frequency of the alternating voltage α and possibly only deviates from its phase by a certain amount Γ 2. The delay element 3 is set so that the output voltage of the drag generator is in phase with the AC voltage proportional to the line current. This voltage is also limited in a limiter element, the limiter element 7, to a value according to line e. The limited alternating voltages b and e derived from the limiter element 1 and from the limiter element 7 are each fed to a bistable multivibrator 8 and 9, respectively. By combining the output voltages of these bistable multivibrators, z. B. with the help of a coincidence gate 10 a phase jump and by adding both voltages in an OR circuit 13, the direction of the phase jump can be determined. A criterion for the direction of the phase jump is displayed via output B and the occurrence of the phase jump is displayed with the aid of the trip relay 11, which is delayed.

If a fault occurs on the monitored line at a certain point in time, then the current at that point in time changes abruptly at one end of the line, namely in terms of its phase and size. The excitation relay 4 (e.g. overcurrent excitation) switches off the alternating voltage for the pull-in generator before the phase angle change, which is delayed by the time delay via the delay element 3, can have an effect. The control DC voltage obtained from the AC voltage in rectifier 5 is stored during the duration of the fault in capacitor C, whose charging or discharging resistor R is switched off by contact k 4 of excitation relay 4, so that the generator can continue to oscillate with unchanged phase position and amplitude . In the event of a phase jump due to a change in the energy flow during normal operation, on the other hand, the control voltage and thus also the phase of the output voltage of the pull-in generator - it must be correct for an error that follows shortly afterwards - can change quickly, since the time constant of the charging or discharging of the storage capacitor is caused by the parallel-connected Resistance is small. The phase jump in the event of a fault has a full effect on the operation of the flip-flop 8, which now emits an opposite polarity. As a result, the coincidence gate 10 no longer supplies voltage for the trip relay 11. This drops out and, after the OR circuit has been queried, issues a trip command both directly to the local switch and via a communication link to the remote switch, provided that this trip command is not there by a local signal or.

blocked here by a signal from the other end of the line. This is always the case if at the same time a corresponding phase jump is detected at the other end.

FIG. 3 shows some circuit details of the exemplary embodiment according to FIG. 1. In FIG. 3, the switching elements designated by 9 and 10 in FIG. 1 and the element designated by 8 are reproduced in extracts. The remaining circuit details of the exemplary embodiment according to FIG. 1 can easily be constructed in the usual manner. As can be seen from FIG. 3, the flip-flop 9 is controlled in each case via a differentiating element consisting of the capacitor C1 and the rectifier GIl. The actual trigger stage consists of the transistors TrI and Tr 2 and is constructed in the usual way. The differentiated and rectified pulses are alternately fed to one of the bases of the transistors via the rectifiers Gl 2 and G / 3, which act as gates. The flip-flop 8 is to be set up in the same way. The output voltages of the transistors are fed into the circuit formed by the rectifiers G / 4 and G / 5 or GZ 6 and GIl and the associated transistors Tr 3 and Tr 4. Then and only then can a current flow through the relay 11 if at least one of the transistors is controlled to be conductive. But this is not the case if the control voltages of the multivibrators are not in phase. In this case z. B. the transistors TrI 'of the flip-flop 8 and Tr 2 of the flip-flop 9 at the same time controlled permeable. In this state, a current flows through the rectifier Gl 6 and GZ 5. As a result, the base voltages of the two transistors Tr 3 and Tr 4 are positive and they are blocked. The trip relay 11 must drop out in this case. The same thing happens if the rectifiers GZ4 and GZ7 are permeable at the same time.

The explained circuit arrangement always works properly when an error occurs on one of the Electricity fed transmission line occurs. In these cases, as mentioned, the current changes according to size and phase, which can be used to switch off the line.

In large interconnected networks, however, the condition often occurs that a connecting line is straight no load current, but only a relatively small charging current that is already in normal Operating state at the ends of the line has opposite direction. In this case, too must be an error on the line, e.g. B. a short circuit can be determined immediately so that the appropriate Line piece can be switched off in time. In this case, of course, there is initially none comparable phase available. According to a further development of the inventive concept, therefore in the event of a sudden use of electricity on the line with the help of a recorded in a defined starting position Vibration generator (multivibrator) given a comparison vibration on the circuit, which enables the monitoring arrangement to be triggered without further aids.

4 shows a circuit arrangement with which this monitoring case, which occurs in practice in special networks, can also be mastered. Insofar as the circuit arrangement contains the same parts as FIG. 1, they are provided with the same reference numerals. The circuit arrangement shown in FIG. 4 also has an excitation relay 4, a limiter element 1, a low-pass filter 2, a delay element 3, a rectifier 5 and a pull-in generator 6. Instead of the flip-flops 8 and 9 shown in FIG. 1, the coincidence gate 10 , the relay 11 and the phase comparison device 13, a somewhat differently constructed measuring device 14 is provided in the embodiment of FIG. This measuring device enables the magnitude and phase position of the frequencies of the drag generator 6 to be compared with one another and the alternating voltage supplied via input A to be determined directly. A known direction relay 15 is provided for this purpose. The sum and the difference of the alternating voltage e output by the oscillating circuit and the voltage i proportional to the line current are fed to this direction relay 15 via the adding circuit 16 and the subtracting circuit 17 via rectifiers 18 and 19. The direction relay only responds if the sum vector e + i is greater than the difference vector e-i (lead of the short-circuit current vector). The circuit arrangement works in the same way as the exemplary embodiment according to FIG. 1. In contrast to FIG. 1, however, a relay N 21 with its contact η is additionally arranged in the circuit arrangement in addition to a few switching elements to be explained. This relay, which is energized in the idle state, drops out when the current drops to a value that is below the response value of the minimum value limiter 20 and corresponds to the charging current of the line, and with its contact switches off the entire measuring device 14 from the voltage of the pull-along generator and to a multivibrator 24, which is initially held in a starting position that determines the phase position of the start of the oscillation, that is to say does not emit any pulses. If there is a fault on the line, the short-circuit current will set in at both ends of the line simultaneously, with a steep edge. The short-circuit current exceeds the threshold value of the limiter 20 and starts the multivibrators. The steep edge causes the simultaneous start-up of these multivibrators, whose vibrations now start with a certain phase position. In addition, the excitation relay 4 responds, which prevents relay 21 from being pulled back on. The multivibrators at both ends of the line emit vibrations that are initially in phase with sufficient accuracy. The frequency of the multivibrator is expediently chosen so that it deviates by a certain amount from the mains frequency, that is to say from the frequency of the current to be transmitted. The voltage emitted by the multivibrator 24 is mixed with the voltage determined from the input current in the manner described above, rectified and fed to the direction relay 15. This responds in a certain rhythm that is dependent on the difference between the two frequencies. The smaller the difference between the frequencies, the longer the tripping time with small phase angle differences in the current at both ends of the line, but the smaller the content of the message to be transmitted and the less susceptible to interference the transmission result. In the case of small phase angle differences, however, a longer tripping time can also be accepted.

With this additional device, the frequency of the short-circuit currents flowing on both sides becomes in phase to a low frequency position (difference between the frequency of the Multivibrators and the line frequency) implemented. The resulting phase beats, the due to the small message content are only exposed to a low level of interference transferred and compared with the local phase beat. Since the multivibrator frequencies, respectively are locally generated, are in phase, a phase angle deviation can be derived from the comparison of the phase beats the original voltage can be derived. Instead of a multivibrator, anyone can use to generate the converter frequency Generator can be used, which can be excited with a defined phase.

The actual trigger circuit 25 consists of a relay 26, which is triggered via the contacts of the direction relay 15 at one end and a direction relay 15 'controlled via the transmission line via the direction relay there, with triggering only occurring when the excitation relay 4 has its contact k 2 had prepared the circuit.

The circuit arrangement described and explained can be implemented in various ways within the scope of the invention Way can be varied. In particular when using the circuit arrangement in multi-phase networks there is the possibility of having a separate trip circuit for each of the three lines Provide a suggestion so that in the event of a fault on one of the three lines, only this can be switched off. The other switching elements can be used uniformly for the multi-phase network.

Claims (8)

PATENT CLAIMS: 1. Circuit arrangement for monitoring the transmission properties of a high-voltage line by comparing the current phases at both ends of the line with each other, the transmission line being switched off when a certain phase difference is exceeded, characterized in that switching means for determining the phase jumps of the fed into the line at each end of the high-voltage line or current taken from the line are provided that determine the occurrence of phase jumps in terms of size and direction and the occurrence of phase jumps in a coded form via a transmission system, e.g. B. in the form of rectangular changes, and thus indicate the direction and size of the phase jump to the comparison and triggering device arranged at the other end via a relatively narrow-band transmission channel for evaluation. 2. Circuit arrangement according to claim 1, characterized in that for the evaluation of Phase jumps at the ends each one via a delay element of the frequency of the high-voltage current A generator drawn along is provided, the output voltage of which is derived from the line current, directly supplied voltage is supplied to a phase comparison device known per se. 3. Circuit arrangement according to claim 2, characterized in that between the delay element and pull-in generator, a switching point is provided which, in the event of erratic phase and / or sudden changes in current using a relay, e.g. B. by means of overcurrent excitation, opened so that the drag generator continues to oscillate in its set phase. 4. Circuit arrangement according to claim 3, characterized in that the time constant one between which the control voltage depends on the load current and the output voltage of the Pull-along generator generated rectifier network and the pull-along generator arranged Timing element is preferably switchable by switching off the timing element and that the smaller one Time constant made effective in the event of phase jumps without a subsequent current overshoot will. 5. Circuit arrangement according to Claim 2 to 4, characterized in that the phase jumps can be indicated with the help of a gate circuit that both voltages (the voltage derived from the line current and supplied by the pull-in generator) to the control unit a flip-flop are used, and that the output voltages of this flip-flop in the Gate circuit can be brought to coincidence or anticoincidence. 6. Circuit arrangement according to claim 1 to 4, characterized in that in addition to the The size of the phase jump and its direction are determined and evaluated in a manner known per se will. 7. Circuit arrangement according to claim 1 to 6, characterized in that at the input the comparison circuit, the output voltage of a vibration generator, preferably Tilting vibration generator in the event of a sudden use of electricity, to which a current of a specified minimum amplitude follows, is released for vibration output with a defined receiving phase and its natural frequency deviates from the Frequency of the current to be transmitted over the line to be monitored is selected. 8. Circuit arrangement according to Claim 1 to 7, characterized in that the comparison circuit is equipped with a polarized relay to which the rectified output voltages one is the instantaneous values of the mains alternating voltage and the comparative alternating voltage adding and subtracting circuit are supplied and that a criterion emits over the direction of energy. Considered publications:
German patent specifications No. 762 923, 884 844. For this purpose 2 sheets of drawings © 909 650/418 11.59 (609 563/584 4. 66)