SU1422286A1 - Relay protection arrangement of tranmisssion line of isolated neutral electric network - Google Patents

Abstract

The invention relates to relay protection and can be used to protect distribution networks against short circuits and asymmetrical damages with a low level of emergency components. The purpose of the invention is to increase reliability by reducing the number of tunable elements. The device contains a mini-selector 1 and a maxislector 2 of the current, a max-selector 3 and a mini-selector 4 voltage, a block 5 for changing the setting of the blocking organ, a block 6 for blocking, a measuring organ 7, a block 8 for inrush current polarity fixation, And 9, 10 elements the delay element 11 and the executive bodies 12, 13. In the case of asymmetrical damage outside the protection zone, stress asymmetries occur, the difference between the minimum and maximum stresses. As a result, asymmetry of load currents in different phases appears, the measuring unit 7 triggers. At the same time, the difference between the minimum and maximum currents is less than the setpoint. As a result, the blocking body does not work. 1 il. (L (L

Description

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; The invention relates to the relay: protection and is intended to protect the power lines of distribution networks from unsymmetrical short circuits.

The purpose of the invention is to increase reliability by reducing the number of tunable elements by introducing simple elements instead of traditional filters that do not require tuning and distinguish an asymmetrical mode.

The drawing shows a diagram of the proposed device.

The device contains a mini selector 1 and a maxislector 2 of rectified and smoothed current, a maxiselector 3 and a mini selector 4 of indirect and smoothed voltage connected to the secured line, the block 5 for changing the setting of the blocking organ, the first input of which is connected to the output of the minislector 1, and the output with the input of the blocking body 6, the output of the measuring body 7 is connected to the second input of the inrush current polarity fixing unit 8, and the first input of the unit 8 is connected to the zero outputs of the maxiselector 2 and the mini current selector 1 by one of the inputs of the first electric ment and 9, the other input of which is connected to the output lock body. The output of the current polarity fixing unit is connected to one of the inputs of the second element I 10, the other input of which is connected to the output of the first element I and the input of the first actuator 12 via the delay element 11 connected to the input of the second element 13.

The device works as follows.

In the case of an asymmetrical short circuit on the protected line, the difference between the absolute values of the minimum and maximum phase currents sharply increases. As a result, the protection measuring body 7 is triggered. The difference between the absolute values of the minimum and maximum stresses also increases. However, the relative increase in the specified voltage difference is less than the increase in the difference of the maximum and minimum current. The ratio between the indicated differences of currents and voltages is such that the blocking body 6 is activated. Work signals from the outputs of the blocking body 6 and the measuring body 7 are fed to the inputs of the first element I 9 and with a time delay defined by the delay element 11, the signal arrives. one of the inputs of the second element And 10, as well as the first executive body 12 acting on the signal. As a result of the presence of a surge current at the time of triggering the measuring

The Q of the organ that reacts to the emergency component also triggers the current surge polarity block 8, the output signal of which is fed to the second input of the second element 10.

5 The latter, as a result of the presence of operating signals at both inputs, changes from zero to one state, which leads to the triggering of the second executive body acting

0 to disable the line. When one wire breaks in the loaded area of the protected line, the blocking body 6, the measuring body 7 and the first executive

5 authority 12, acting on the signal. However, the total current surge at the first moment has a negative sign (or is equal to zero) and block 8 does not work, as a result of which the second executive

0 organ 13 does not work, but only a break in the organ 12 is in place.

In case of asymmetrical damage outside the protection zone (for example, on the adjacent line), voltage asymmetry occurs, i.e. the difference between the minimum and maximum controlled voltages increases. Under the action of this, asymmetry of load currents appears in different phases of the protected connection and the difference between the minimum and maximum phase currents increases, as a result of which the measuring unit 7 can operate. However, the difference between the minimum and maximum voltages has the same value as in the considered case of asymmetric short-circuit on the protected line in the zone of protection, and the difference between the maximum and minimum currents is less than in the previous case. Since this current difference is a working signal of the blocking body 6, as which the resistance relay is applied, the latter does not work, blocking the protection action. This ensures the selectivity of the device.

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Claims (1)

Invention Formula Relay protection device of power line with insulated neutral network, containing measuring body reacting to emergency current component, block for changing setpoint of blocking organ, blocking body for which resistance relay is used, working input of which is connected to output of block for changing setpoint, polarity fixation block inrush current, the control input of which is connected to the output of the measuring organ, the first element I, the inputs of which are connected to the outputs of the blocking organ and measuring rgan, delay element, first executive body, second element I and second executive body, with delay element and first executive body successively connected to the output of the first element And, and the input of the second executive body connected to the output of the second element I, whose inputs are connected to the output of the element delay and block fixing the polarity of the inrush current, characterized in that, in order to increase reliability by reducing the number of tunable elements, max-selectors and mini-selectors of rectified and smoothed currents and voltages are added, connected to the terminals for connection to the protected network, and zero points of the max-selector and a mini-current selector are combined and connected to them are the control input of the unit for changing settings, the brake input of the measuring organ, and the operating input of the inrush current polarity fixing unit, to the operating output m the current selector connects the working inputs of the unit for changing the settings and the measuring unit, the zero points of the max selector and the mini voltage selector are combined, the brake input of the blocking organ is connected to the working output of the high speed selector, and the operating outputs of the current max selector and mini voltage selector are connected to the terminal for connecting to zero point circuitry of the entire device.