SU1229896A2 - Device for selecting damaged phase for protection of aerial electric power line against short circuit - Google Patents

Abstract

The invention relates to electrical engineering, can be used in relay protection for selecting a faulty phase, during a short circuit on an overhead transmission line, and is complementary to the auth. No. 1148071. The purpose of the invention is to increase the reliability of operation by increasing the selectivity and speed of operation with non-phase-phase pe (L fsj

Description

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presses and in the transition from one type of damage to another. The device contains a block of compensation of current currents of zero sequence (BCFT) 7, connected to the network through converters 4, 5, 6 and current transformers (CT) 1,2,3. The outputs of BCFT 7 through the emergency components allocation unit (BSA) 8, 9, 10, the driver of the emergency component modules (FMAS) 11, 12, 13 and the keys 14, 15, 16

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The invention relates to electrical engineering, can be used for relay protection and linear automation of power systems and is an improvement of the device according to the basic author. St. 1148071.

In the known device for selecting the faulty phase to protect the overhead power line from short-circuiting, incorrect actions are possible in non-full-phase modes and during transitions of one type of damage to another, as well as slowing down of operation at such transitions.

The purpose of the invention is to increase the reliability of the operation of the device by increasing the selectivity and speed in the case of an incomplete phase mode and in the transition from one type of damage to another.

The drawing shows a block diagram of the device.

The device contains measuring inputs of 1–3 phase currents and 4–6 phase currents transducers connected to them phase by phase, the outputs of which are connected to block 7 for compensation of phase currents by zero-sequence current. The outputs of block 7 are connected in phase to the inputs of blocks 8 to 10, the selection of emergency components, the outputs of which are connected to the inputs of blocks 11-12 of forming the modules of emergency components, respectively, the outputs of which are connected to the inputs of logical switches 14 to 16. The outputs of logical keys 14 are 16 are connected in phase directly to the first inputs of two-input comparators 17 19 connected to two-input comparators (DC) 17, 18, 19, the outputs of which through the elements OR 24, 25, 26 are connected to the keys 14, 15, 16. The second inputs of DC 17, 18, 19 through the mini-shop p 20 are connected to the outputs of the keys 14, 15, 16. An apparatus based on the use of comparing variables constituting the emergency phase currents allows a small time detects one or both be damaged phase, i yl.

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responsibly and through the unit of formation of the reference voltage, made in the form of a mini-selector 20, to the combined second inputs of these comparators. The outputs of the comparators 21–23, which are simultaneously the outputs of the device, are connected to the first inputs of logical elements OR 24–26, respectively, the second inputs 27 to 29 of which are the logical inputs of the device. The specified logical inputs of the device are connected to the signals from the relay position Disconnected corresponding phase switches of the protected power line (not shown). The outputs of the OR elements 24-26 are connected to the control inputs of the logical keys 14-16, respectively.

The measuring transducers of 4-6 currents provide at their outputs voltage proportional to the phase currents in the whole range of their change. In block 7, which is a summing device, the phase currents are compensated for the zero-sequence current. In addition, in block 7, the possibility of adjusting the compensation coefficient is provided.

Blocks 8-10 of the emergency component are a circuit in which its input voltage is summed up with the output voltage of an inertia unit connected to. the input of the block and the execution either in the form of a delay line, or in the form of a band-pass filter. The inertial link is tuned so that in the steady state frequency frequency, the voltage at its output is equal in magnitude and opposite in phase to the input voltage. Therefore, when these voltages are added in a steady state at the output of blocks 8-10, there is no output signal.

Blocks 11–13 are superior with smoothing or integrating links,

Each logical key 14-16 is open, i.e. passes the value connected to its inputs to the output as long as there is no signal at the control input of the key. When the signal appears at the control input of any key, the corresponding emergency component of the current is excluded from the operation of the device.

Block 20 is made in the form of a mini-selector, the output of which has a voltage proportional to the minimum phase of the emergency component. This voltage is the reference for the phase-by-port double-input comparator 17-19.

The device works as follows.

With short-circuit, the instantaneous value of the electrical quantities at the outputs

distributors 4 - 6, as well as at the exit

block 7 (i.e., at the inputs of block 8-10) change in jumps, and the other (at the output of the inertial link) at the expense of the storage properties of the inertial link for some time, determined by the parameters of the link, retains a value proportional to the pre-emergency current . Thus, the sum of these two voltages, proportional to the corresponding phase emergency component of the current, in the short-circuit mode appears abruptly at the output of blocks 8-10 and remains for some time. In blocks 11-13, direct current voltages are generated, the magnitude of which is proportional to the values of the corresponding emergency currents. The voltages from the outputs of the blocks 11–13 through the open logic switches 14–16 are fed to the inputs of the phase comparators 17–19, where phase-wise comparison is made to the minimum of them, which appear at the outputs of the mini selector 20 and is the reference voltage KOM parators.

In the case of single-phase short circuits to earth, the emergency current component of the damage is j

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According to studies for high-voltage and ultra-high voltage networks, under extreme conditions, it is no less than 1.2-1.3 times more than the emergency components of currents of intact phases, which are equal to each other. The voltage is proportional to the emergency component of the current of one of the intact phases, and is the reference voltage of the comparators. If the criterion for triggering a phase comparator is to choose the condition for exceeding the magnitude of the phase emergency component 1.2-1.3 times relative to the reference component, then in the case under consideration only the comparator of the damaged phase is triggered.

With two-phase faults, the emergency components of the currents of the damaged phases, although in the general case they are not equal to each other, but also by no less than 1.2-1.3 times exceed the emergency component of the intact phase. Therefore, in this case, two comparators of damaged phases are put off;

In the case of an incomplete network mode, when one of the phases of the power line, for example, phase A, is disconnected from the Disabled Disable Phase switch, the device logic input 27 and, therefore, the control switch of the logic switch 14 through the OR 24 element receives a signal the effect of which eliminates the effect on the operation of the device of the circuit of the disconnected phase.

With short circuits on high and extra high voltage power lines, including transitions of single-phase short circuits into two-phase short circuits to earth, intense and long-term transients may occur in power lines as well as in the phase separation circuits of the emergency components of the current under consideration. devices. Such transients in the 14 Deleted emergency circuit comprise the first damaged phase, which is detected by the appearance of a signal on. the output 21 of the comparator 17 could either lead to an incorrect determination of the subsequent closed phase or to a slowdown in the determination of this phase. Therefore, the influence of the transient process in the circuit of the first damaged phase A on the operation of the device is eliminated by a logical key 14, the control input of which in this Case receives a signal through the first input of the OR element 24 from the output 21 of the comparator 17.

Thus, the proposed device, based on the use of a comparison of the aerial values of the phase currents, allows for a short time (about the half-period of the industrial frequency) to reveal one damaged phase during single-phase closures, both damaged phases with other types of asymmetrical short-circuits, as well as to function correctly in non-phase-phase modes and transitions of one type of damage to another,

Claims (1)

Invention Formula . A device for selecting a damaged phase to prohibit overhead transmission from short circuit to. IP 1148071, characterized in that, for the purpose of higher Editor V. Petrash Order 2456/56 Compiled by V. Molchanov Tehred M. Khodanych, Proofreader M. Pojo Circulation 612 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4 neither the reliability of operation by increasing the selectivity and speed in case of an incomplete phase mode and when one type of damage is transferred to another, the first, second and third logical keys and the first, second and third elements of OR are additionally introduced, each logical key is switched phase by phase between the output and the input of the corresponding the module for forming the emergency components module and the module for forming the voltage on the basis of a mini-selector; the control input of each logical key is connected to the output One of the corresponding element OR, the first input of which is connected to the output of the position relay. The corresponding phase switch is turned off, and the second input of each element OR is connected to the output of the two-input comparator of the corresponding phase.