RU2162268C2 - Ice-load group screening device for overhead power transmission lines - Google Patents

Abstract

FIELD: power engineering. SUBSTANCE: proposed device that can be used in group ice-load telemetering systems incorporating arbitrary number of monitoring stations at various sections of isolated-neutral power transmission lines provides for group screening of ice load by transmitting data in the form of low-frequency pulse train over phase- to-ground channel. Warning device installed in ice-load monitoring station has transducer that functions to convert ice-load sensor signal to corresponding pulse-number code combination in the form of sequential time-repetitive low- frequency pulses. Alternate information is transmitted by asynchronously running warning devices due to introduction of comparator-controlled cycle- shaping counter and delay-shaping counter in warning-device circuit. With vacant channel available, transducer simultaneously measures ice load and transmits respective pulse-number code combination within one working cycle at different initiation time of transmission in all warning devices. Voltage across receiving-unit input remains sufficient for reliable counting of the number of arriving pulses and decoding data received in spite of decay of low- frequency signal during partial short-out of phase-to-ground channel. EFFECT: improved reliability of group ice-load screening. 1 dwg

Description

 The invention relates to the electric power industry and can be used to create regional group systems for measuring ice loads with an arbitrary number of control points on various power lines in networks with isolated neutral.

 Known devices for measuring ice load in several network monitoring points with contact sensors for ice load and transmitting the sensor response signal with a DC signal with time-pulse coding according to the phase-ground scheme [1-2]. The disadvantages of these devices are: the inability to continuously monitor the icy load and the intensity of its growth, the low reliability of the contact sensor, as well as the need to use synchronization units at the control points and at the receiving point to recognize at which point in the network the contact of the icing load sensor was triggered.

 Replacing the contact sensor with a contactless one in the device [3] made it possible to continuously monitor the ice load with the transfer of information about its value to the DC voltage value. This device, which is the closest analogue, contains a receiving unit, the input of which is shunted by the first capacitor and connected between the first ground terminal and a choke with a terminal for connection to a phase wire insulated from the ground, and at least one signaling device equipped with an icing load sensor equipped with a converter the output signal of the icing load sensor into a proportional DC voltage, the output of which is shunted by a second capacitor connected between the second terminal oh earth and the primary winding of the transformer to the terminal for connection to the phase conductor transmission line.

 The disadvantages of this device are the inability to control the ice load at several points of the network control on various power lines, the presence of an error in the control of the ice load when the insulation resistance of the network is reduced or when voltage transformers with grounded neutrals are connected to the network when partial shunting of the phase-to-ground transmission channel occurs.

 The invention is aimed at solving the problem of reliable continuous group monitoring of ice load with an arbitrary number of control points on various power lines while reducing the insulation resistance of the network under adverse atmospheric conditions or when voltage transformers with a grounded neutral are connected to the network.

 The specified technical result is ensured by the fact that in the device containing the receiving unit, the input of which is shunted by the first capacitor and connected between the first ground terminal and the inductor with the terminal for connection to the phase wire, and at least one signaling device made with an icing load sensor, the output of which is bypassed the second capacitor and is connected between the second ground terminal and the primary winding of the transformer with a terminal for connecting to a phase wire, a converter is used in the signaling device the sensor output signal proportional to the icing load, the counter-shaper, the counter-shaper of the time delay, an electronic key, a comparator, a low-pass filter and a low-frequency pulse shaper, the output of which is connected through an electronic key to the input, are additionally added to the corresponding number of low-frequency pulses and to the signaling device converter and to the counting inputs of the counter-shaper of the cycle and the counter-shaper of the time delay, and the control input of the electronic key and page The inhibitory input of the comparator connected to the counter outputs paraphase-shaper time delay, the zero input of which is connected to the output of the shaper-meter cycle, the zero input of which, in turn, connected to the output of the comparator included through low-pass filter parallel with the second capacitor.

 The essence of the invention is illustrated by the functional diagram of the device shown in the drawing for the case of one point of control of ice load on the power line.

 The device contains a receiving unit 1 installed at the place of receiving information, the input of which is shunted by the first capacitor 2 and connected between the first ground terminal 3 and the inductor 4 with a terminal for connecting to the phase wire 5. A transformer 6 is installed at the ice load control point, the primary winding of which is connected in series with a second capacitor 7 between the wire 5 and the second ground terminal 8. In parallel with the capacitor 7, an alarm 9 is turned on, consisting of an icy load sensor and an output converter the sensor signal into the corresponding number of low-frequency pulses 10, an electronic key 11, a low-frequency pulse shaper 12, a cycle shaper counter 13, a time delay counter-shaper 14, a comparator 15, and a low-pass filter 16. The output of the low-frequency pulse shaper 12 is connected via an electronic key 11 to the input of the converter 10 and to the counting inputs of the counter-shaper of the cycle 13 and the counter-shaper of the time delay 14. The diminishing input of the electronic key 11 and the gate input of the comparator 15 are given to the paraphase outputs of the counter-shaper of the time delay 14, the zero-setting input of which is connected to the output of the counter-shaper of the cycle 13, the zero-setting input of which is connected to the output of the comparator 15, connected through the low-pass filter 16 in parallel to the second capacitor 7. The signaling circuit is powered by the secondary winding of the transformer 6 through the power supply of the signaling device 17.

 The device operates as follows.

 During one operating cycle T, the duration of which is set by the counter-shaper of cycle 13, the signaling device 9 performs one measurement of the value of the ice load and the transmission of the corresponding number-pulse code combination in the form of the number of low-frequency pulses following one after another, received through the electronic key from the low-frequency pulse shaper 12. Despite the signal attenuation during partial phase-to-ground channel shunting, the voltage at the input of the receiving unit remains sufficient for reliable a complete account of the number of incoming pulses and decoding the received information.

 To increase the noise immunity of the device from random pulsed interference, the transmitted code combination consists of a predetermined number of preparatory pulses, followed by information ones, the amount of which depends on the load value and the selected quantization step. At several points of monitoring the icy load on various power lines, preparatory pulses in the code combination are followed by address pulses, and the converter 10 generates a number-pulse code combination with an extended separation pulse between the address pulses (address code) and information pulses (code of the load value), during which the phase-ground channel remains excited, the polarity of the signal at the input of the receiving unit cannot change and it reliably recognizes which that information comes control.

 As the transducer 10 can be used, for example, a digital transducer encoding the value of the ice load by the balancing method, that is, when a known discrete value is formed directly during the measurement until it becomes equal to the measured value. The process of discrete balancing in this case occurs directly during the transmission of information by the signaling device.

 The transmission of the code combination begins after the delay time Δt after the start of the cycle generated by the counter-generator of the time delay 14, decreasing with the electronic key 11. The introduction of different delay times for all signaling devices of the group television system for measuring ice loads ensures their alternate asynchronous operation while turning on the power.

где n - число сигнализаторов в системе; t_makci - максимальное время передачи информации i - и сигнализатором; Δt_i - время задержки i-го сигнализатора.During the delay time Δt, the signaling device 9 checks whether the phase-ground channel is free, for which there is a low-pass filter 16 and a comparator 15, which during this period of time is released by the counter-driver of the time delay 14. If the channel is busy and information from another signaling device is transmitted through it , periodic operations of the comparator 15 each time reset the counter-shaper of the cycle 13 and the counter-shaper of the time delay 14. Thus, the signaling device goes into standby mode and there is a shift by ala its working cycle than capable of transmitting multiple detectors without synchronization of their operation. The duration of the working cycle is chosen equal

where n is the number of signaling devices in the system; t _makci is the maximum information transfer time i - and the signaling _device ; Δt _i is the delay time of the i-th detector.

Sources of information
1. Dyakov A.F., Levchenko I.I. The experience of dealing with icing on power lines // Electric stations, 1978, N1, p. 50-54.

 2. A.S. 1381637 (USSR). The device alarm about ice / R.N. Rudakova, P.P. Abdullin, K.A. Abzalov //15.03.88, BI N10.

 3. A. p. 1539885 (USSR). Device for monitoring icy load on wires or cables of power lines / Yu.I. Lyskov, B.C. Molodtsov, M.M. Seredin / 01/30/90, BI N4.

Claims (1)

 A device for controlling icing load on overhead power lines, comprising a receiving unit, the input of which is shunted by the first capacitor and connected between the first ground terminal and a choke with a terminal for connecting to a phase wire, and at least one signaling device made with an icing load sensor, the output of which is connected in parallel with the second capacitor connected between the second ground terminal and the primary winding of the transformer with a terminal for connecting to a phase wire, different that each detector contains a sensor output signal proportional to the icing load, the corresponding number of low-frequency pulses, intended for transmitting this information by the detector, which additionally includes a counter-shaper of the cycle, a counter-shaper of the time delay, an electronic key, a comparator, a low-pass filter and shaper of low-frequency pulses, the output of which is connected through an electronic key to the input of the converter, counter-shaper cycle, com the parator and the counter-driver of the time delay are designed to ensure information transfer by signaling devices without synchronizing their operation, the control input of the electronic key and the gate input of the comparator are connected to the paraphase outputs of the counter-driver of the time delay, the zero-setting input of which is connected to the output of the counter-driver of the cycle, the installation input which zero, in turn, is connected to the output of a comparator connected through a low-pass filter parallel to the second capacitor.