SU1720122A1 - Power direction relay - Google Patents

Abstract

Use: relay protection of power lines with increased sensitivity. The invention: the device contains a phase comparison unit consisting of a four-input adder 12 with the same input resistors 13-16, each of which is connected in pairs with diodes 17 and 18, 19 and 20, 21 and 22, 23 and 24, and to resistors 13 and 14 diodes are connected with anodes, and resistors 15 and 16 are connected with cathodes. The cathodes of each pair (diodes 17, 18, and 19, 20 are connected to the unipolar terminals of the dual-winding secondary windings of the voltage sensors 1 and current 2, the anodes of each pair of diodes 21, 22 and 23, 24 are connected to the opposite terminals of the voltage and current sensors respectively. The pulse width at the output of adder 12 is proportional to the phase angle. The fixed angle is fixed when the pulses of one-vibrators 7, 8 coincide with the high level signal of the former 5. 3 ill. CO

Description

The invention relates to electrical engineering, namely, to relay protection, and can be used in devices for relay protection of power lines.

A power direction relay is known that contains blocks of positive and negative signs of current and voltage, a two-pulse counter, an integrator and an integrator reset unit, a reacting organ.

The disadvantage of this relay is that it can malfunction when there is an aperiodic component of the total current.

A device for directional current protection is also known, comprising current and voltage sensors, a threshold unit, three square pulse formers, two delay units, two differentiation units, an inverter, a pulse limiter, And element, an execution unit.

A disadvantage of the known device is that at short-circuit currents the current transformers become saturated and the shape of the current curve becomes non-sinusoidal, and a single and even twice differentiation of such a signal can lead to non-selective triggering of the device.

The closest to the present invention is a power direction relay comprising voltage and current sensors, a geometric difference unit and an arithmetic summation unit, a reference element, two pulse makers, an inverter, two single vibrators, two D-flip-flops, a logic element And and an actuator,

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moreover, the arithmetic summing unit is made in the form of two series-connected diode bridges, and the geometrical difference unit is made in the form of a diode bridge with dividing diodes.

The disadvantage of this relay is the presence of a dead zone due to the opening threshold of four series-connected diodes in the arithmetic summation unit and three series-connected diodes in the geometric difference unit.

The aim of the invention is to increase the sensitivity and simplify the relay.

The goal is achieved by the fact that the power direction relay contains current and voltage sensors, two square pulse formers, the input of the first of which is connected to the output of the voltage sensor, and the second input is connected to the output of the comparison unit, the input of which is connected to the outputs of the blocks geometrical difference and arithmetic summation, while the output of the first square pulse generator is connected via a series-connected inverter and the first one-oscillator to the C input of the second D flip-flop, the D input of which It is connected to the output of the second rectangular pulse driver and to the D input of the first D-flip-flop, the C-input of which is connected via the second one-oscillator to the input of the inverter. Pa and the actuator, current and voltage sensors are made in the form of an intermediate transreactor and a transformer, respectively, with two identical series-connected secondary windings, the connection point of which is connected to the terminal for connection to the common bus of the device, the geometric difference unit is made in the form of four diodes, the cathodes of which connected to one-dimensional terminals of the secondary windings of voltage and current sensors, and the arithmetic sum block is made in the form of four diodes, the anodes of which are connected to different conclusions dimensional sensor voltage and current, a second D-flip-flop is provided with a R-input connected with the output of the first D-flip-flop, and the output of the second D-flip-flop is connected to the actuator body.,

Figure 1 shows the functional diagram of the relay; 2 and 3 are timing diagrams explaining its operation.

The relay contains a voltage sensor 1 and a current sensor 2, made in the form of an intermediate transformer and a transreactor, respectively, with two identical series-connected secondary windings, the junction point of which

connected to a common bus device, a unit of geometric difference 3, made in the form of four diodes, the cathodes of which are connected to one-dimensional secondary terminals

5 windings of voltage sensors 1 and current 2, a block of arithmetic sum 4, made in the form of four diodes, the anodes of which are connected to the dimensional outputs of voltage sensors 1 and current 2, block 5 compared, the input of which is connected to blocks of geometrical difference 3 and arithmetic sum 4, square pulse driver b, the input of which is connected to the secondary winding of the voltage sensor

5 1, a square pulse shaper 7, whose input is connected to the output of the comparison unit 5, an inverter 8, whose input is connected to the output of the square pulse shaper 6, a single vibrator 9,

0 whose input is connected to the output of a rectangular impulse generator 6, a single vibrator 10 whose input is connected to the output of an inverter 8, a D-flip-flop .11. The C-input of which is connected to the output of the one-vibrator 9, and the D-input to the shaper of 7 square pulses, D-flip-flop 12, the C-input of which is connected to the output of the one-vibrator 10, D-input to shaper of rectangular pulses 7 , and R-input - to the output

0 D-flip-flop 11, the executive body 13, the input of which is connected to the output of the D-flip-flop 12.

Comparison unit 5 is made in the form of a four-input accumulator 14 with the same

5 input resistors 15-18, coupled diodes of the geometrical difference unit 3 are connected to the input of each of the resistors 15 and 16, while the cathodes of each pair of diodes are connected to unipolar pins

0 voltage sensors 1 and current 2, and the inputs of resistors 17 and 18 are connected in pairs to the diodes of an arithmetic sum unit 4, while the anodes of each pair of diodes are connected to the opposite terminals of sensors 5 and 1 and current 2, respectively.

The relay works as follows. The output signals of unit 3 of the geometric difference depend on the angle between the voltage vectors of the secondary windings

0 voltage sensors 1 and current 2, with each pair of diodes determining the difference for the positive and negative half-voltage, respectively. Each pair of diodes of the arithmetic sum block 4 is a full-wave rectifier of the voltage and current sensors 1 and 2, respectively.

The width of the resulting signal Up (Fig. 2) at the output of the comparison unit 5 in the range of angles between the voltage vectors

and a current of 180-360 ° is proportional to the phase angle, with the beginning of the leading edges of the voltage curve and the resulting signal coincide, and in the angle range of 0-180 ° the width of the resulting signal Up is inversely proportional to the phase angle, while the ends of the falling edges of the voltage curve and the resulting signal (Fig.2A).

If there is an aperiodic component in the full current, the coincidence zone of the beginnings and ends of the edges of the voltage curve and the resulting signal is narrowed sinusoidally. This narrowing, for example, at 30% of the aperiodic component is arcsin 0.3 17.5 ° for each quadrant, i.e. the width of the relay operation zone with such an aperiodic component will be 145 ° (Fig. 2b), for 70% of the aperiodic component, the operation zone of the relay will be 91 ° (Fig. 2c) ..

When the aperiodic component exceeds the periodic for a whole period, the relay does not operate.

Phase voltages and currents are supplied to the inputs of the voltage and current sensors, the output of which transforms and out of phase voltage Ui and Ui, U2 and U2 are fed to the input of the comparison unit 5 (Fig. 3, voltage Ui and Ua are not shown ), with the voltage at the output of the transreactor U2 and U2 shifted relative to the primary current by 90 ° (based on the principle of the open transreactor). Voltage Ui is also supplied to the input of pulse generator 6. The resulting signal from block 5 of comparison is fed to square pulse driver 7 (Fig. 3). In shaper 7 and 6, the signals are converted into rectangular pulses U4 and Us, respectively (Fig. 3). The pulses U4 formed in the driver 7 are fed to the D inputs of the flip-flops 11 and 12. A pulse corresponding to the positive half-wave voltage from the driver 6 is fed to the input of the one-oscillator 9, and the inverse pulse corresponding to a negative half-wave voltage Ue from the inverter 8 is fed to the input of the single-oscillator 10 Low level pulses U and Us (Fig. 3) with one vibrators 9 and 10 are applied to the C inputs of the flip-flops 11 and 12, respectively.

With the same change in the width of the pulses of both single vibrators, the relay triggering zone changes without changing the trigger range, for example, when the pulse width at the output of both single vibrators is 30 °, the trigger zone will be in the range 150330 °, i.e. the range of operation remained 330-150-180 °.

In the mode of direct current in the range of angles 0-180 ° with or without aperiodic component 5 of the total current, the leading edge of the pulses from the former 7 does not coincide with the leading edges of the pulses from the former 6 and the inverter 8, therefore, the leading edges of the synchronizing pulses do not coincide. pulses from one-shot and Yun C-inputs of triggers 11 and 12 with high-level pulses on the D-inputs of these triggers. The triggers do not switch, the relay does not work (Fig. Za.b).

5 In the mode of reverse current in the range of 180-360 ° C. With or without aperiodic component of the total current, the leading edges of the clock pulses coincide with the high-level pulses at the 0 D inputs of the flip-flops 11 and 12. The flip-flop 11 switches, removes the prohibition from the set R-input of the trigger 12 (Ug), the latter switches (Uio), the relay triggered (Uii, fig.Zv.d).

5 In the normal mode, the angle between the voltage and the current at the input of the voltage and current sensors is assumed to be close to zero. The angle between the voltages on the secondary windings of the voltage and current sensors 0 (the transreactor is not loaded) is approximately 90 °. At angles between primary voltages and currents of 0–180 ° and without an aperiodic component, the relay does not operate, and at angles of 180–360 ° it operates. At 50% 5 aperiodic component, the triggering zone of the relay is between 210-330 °.

The relay does not operate when the voltage transformer is broken, as in this case there are no signals from the 5 0 comparison unit (the current signal is mutually compensated at the input of the adder 14) and the driver 6.

The relay has a high noise immunity, since its operation under the action of interference can only occur if the interference in the short time interval of the single vibrators is doubled, i.e. the front of the signal of the one-shot 9 with a high level of the signal of the driver 7 in one half period and the front of the signal of the one-shot 10 with a high level of the driver 7 in the other half period must match. Over the rest of the time when the same vibrators are not excited, the triggers 11 and 12 do not change their state.

At the input of unit 5, comparisons in the circuits of rectification are applied: s ;. go through one diode, as a result of which: m: insensitivity compared to .. m is reduced

while simplifying the relay. The relay operates at 1% residual voltage.

Claims (1)

The invention of the Power Directional Relay, contains current and voltage sensors, two square pulse drivers, the first of which is connected to the output of the voltage sensor, and the second to the output of the comparison unit, the input of which is connected to the outputs of the geometric difference and arithmetic sum blocks , while the output of the first rectangular pulse driver is connected via an inverter and the first one-oscillator connected in series to the C input of the second D-flip-flop, the D input of which is connected to the output of the second a rectangular pulse shaper and the D-input of the first D-flip-flop. The C input of which is connected via a second one-shot to the inverter's input, and an actuator, characterized in that, in order to increase the sensitivity and simplification of the relay, the current and voltage sensors are made as an intermediate transreactor and transformer, respectively, with two identical series-connected secondary windings, the connection point of which is connected to the terminal for connection to the common bus device, the geometric difference unit is made in the form of four diodes, the cathodes of which are connected to the one-dimensional terminals of the secondary windings of the voltage and current sensors, and the arithmetic sum block made in the form of four diodes, the anodes of which are connected to the bipolar pins of the voltage and current sensors, the second D-flip-flop is equipped with an R-input connected to the output of the first D-flip-flop, and the output of the second D-flip-flop is connected to the actuator. Fm.1 hch u to