SU1197001A1 - Device for compensating capacitance current of one=phase earth leakage - Google Patents

Abstract

1. DEVICE FOR COMPENSATION OF CAPACITIVE CURRENT OF SINGLE-PHASE ON LAND, containing a discrete arc-suppressing reactor, one of which is connected to the neutral of the transformer connected to the network, and the second output / through the current transformer to ground, the unit of selection of the damaging phase connected to the windings phase voltage transformer voltage connected in series connected to the zero-sequence winding of the transformer voltage first phase-shifting unit, the first driver of rectangular impulses s and a phase-sensitive element is connected in series is connected to the first output phase vybora.povrezhdennoy first filter unit of the fundamental frequency and a second generator rectangular, pulse, whose output is connected to a second input of the first phase change element serially connected sub; The second phase-shifting unit connected to the winding of the phase voltage of the transformer of the voltage transformer is the second phase sensitive element, the second phase-sensitive element connected in series to the zero voltage winding of the voltage transformer the second filter of the fundamental frequency, a quarter of the rectangular pulse generator whose output is connected with the second input of the second phase-sensitive element, as well as the reactor control unit connected by one input to the current transformer, from In order to improve network tuning accuracy and reliability, the SL mode, six keys, a series-connected amplifier, a third phase-shifting unit, a five square pulse shaper, a first short pulse shaper to the front and the back front, the first logical element (; o, the cop, the first pulse counter, the RS flip-flop, are connected in series to the sixth driver of the rectangular 1 X pulses, the second formirotivator of short pulses on the front and rear front , the second logical element is And, the second pulse counter, the output of which is connected to the second input of the RS flip-flop, and the outputs of phase-sensitive elements are connected to the control input of the reactor control unit, respectively, through the first and second keys, the following three keys are connected to the winding of phase voltages voltage transformer, their output is connected to the input of the force

Description

the body, and the control inputs, respectively, with the second, third, and fourth outputs of the damaged phase selector unit, the sixth key-switched between the RS flip-flop and the control input of the reactor control unit, and the control inputs of the first, second and sixth keys are connected to the corresponding the outputs of the network mode determination unit, the output of the first counter is connected to the installation input of the second counter, and the output of the second counter is connected to the installation input of the first counter, the first and the fifth outputs are connected to the damaged phase selection unit With the second and third inputs of the network mode determining unit, a fourth output of which is connected to the blocking input of the reactor control unit, the first input of the network mode determining unit and the input of the sixth rectangular impulse former are connected to the voltage winding voltage circuit.

2. The device according to claim 1, characterized in that the network mode determination unit comprises three variable voltage converters into a logic signal with voltage settings, a fundamental frequency filter a logical element NOT, a logical element OR, three logical elements AND, and one logical element YNE, and to the first input of the network mode determination unit are connected

the inputs of the first two variable-voltage to logic converters

the signal to the second input is the input of the fundamental frequency filter, a. the input of the logical element is NOT connected to the third input and the first input of the logical element OR, the output of the logic element. It is NOT connected to the first input of the first logical element AND, the non-inverted output of the first variable voltage converter to the logical signal is connected to the second input of the OR logical element and to the first input of the third logical element AND, and its inverse input to the BTopbw input of the first logical element AND The A-inversion output of the second AC voltage converter into a logic signal is connected to the first input of the second logic, And signal, and the inverse output to the second input of the third logic I, non-inventive The third output of the third voltage transformer into a logic signal is connected to the first input of the NAND logic element, and the inverse output to the second input of the second logical element AND, the output of the logical element OR connected to the second input of the logical element NAND, the outputs of the first, second and The third AND logical elements and the NAND logical element are connected respectively to the four outputs of the network mode-determination unit.

The invention relates to electrical engineering, in particular to the field of electrical networks.

The purpose of the invention is to improve the accuracy of setting the compensation and network reliability.

FIG. 1 shows a functional diagram of a device for compensating the capacitive current of a single-phase earth fault; on f “years. 2 - functional diagram of the block of choice, the damaged phase; in fig. 3 is a functional diagram of a network mode determination unit; in fig. 4 shows a stylized voltage diagram of the block for selecting the faulty phase and the block for determining the network mode; in fig. 5 is a functional diagram of a control unit of a discrete arc-suppressed reactor.

A transformer 1 is connected to the electrical network, between which a neutral and the earth are connected in series a discrete arcing reactor 2 and a current transformer 3. A reactor control unit 4 is connected to the reactor and controls its keys. A winding connected to the star of the transformer 5 of the supply voltage is connected to the block 6 for selecting the damaged phase. Between the zero-sequence winding of the voltage transformer 5 and the control input of the reactor control unit 4 are connected in series the first phase-shifting unit 7, the driver of 8 square-wave pulses,

a phase sensitive element 9 and a key 10. Between the first output of the damaged phase selection unit 6 and the second input of the phase sensitive element 9 are connected in series the first filter 11 of the fundamental frequency and the second driver 12 of the rectangular pulses. A second phase-shifting unit 13, a third driver 14 for rectangular pulses, a second phase-sensing element 15 and a second switch 16 are connected in series between the star-connected winding of the star transformer 5 and the control input of the reactor control unit 4. The second phase-sensing element 15 and the second switch 16 are connected between the zero-sequence winding of the transformer 5 The second fundamental frequency filter 17 and the fourth square pulse shaper 18 are connected in series with the second input of the phase sensitive element 15. Three keys 19 21 are connected to the corresponding outputs of the damaged phase selection unit 6, the outputs of which are connected to the input of the amplifier 22. The latter is connected to the control input of the reactor control unit 4 via serially connected: the third phase-shifting unit 23, the fifth driver 24 rectangular pulses, the first shaper 25 short pulses on the front and rear front, the first logical element And 26, the first counter of 27 pulses, RS-trigger 28 and the sixth key 29. Between the zero-sequence winding of the transformer 5 eg and the second input of the RS flip-flop 28, the sixth pulse shaper 30, the second short pulse shaper 31, the front and rear edges, the second logic element 32 and the second pulse counter 33 are connected in series. The network mode determination unit 34 is connected to the same winding of the transformer. 5. The corresponding outputs of it are connected to the control inputs of the first, second, and sixth keys and the blocking input of the reactor control unit 4. -.

Block 6 contains three variable voltage transducers 35-37.

into a logical signal with settings for voltage, three AND 38 - 40 logic elements, OR 41 logic element, time block 42, 43 - 45 keys and amplifier 46.

The network mode determination unit 34 contains three variable voltage converters 47 - 49 into a logic signal with voltage settings, a filter 50, a fundamental frequency, a NOT 51 logical element, an OR 52 logical element, three AND 53 - 55 logical elements and an AND - NOT .56. The control unit 4 of the discrete arc-suppression reactor contains a directionally connected trigger 57, an AND 58 logic element, a reversible counter 59. Three decoders are connected to the output of the latter: roughly 60, exactly 61 and more precisely 62,

which are connected to the control signal generation unit 63. A shaper 64 rectangular pulses, a divider 65, and an AND 66 logic element are also sequentially included. In the circuit, there is also a count limiter 67. The control signal generation unit 63 is intended for. amplification of the transmitted signal power and matching of pa: parameters of the power circuits of the reactor thyristors and circuits

management

The block 6 for selecting the faulty phase is designed to determine the faulty phase of the network in case of single-phase earth fault and voltage release at the location of the circuit Uj and the phase voltage of the faulty phase.

The network mode determination unit 34 serves to recognize the network operation modes and obtain the corresponding logical signals, the use of which in the compensation system provides the necessary algorithm for its operation. Consider the operation of these two units as a whole in different modes of network operation.

The phase voltages of the network PD, Ug, Uj, (Fig. 2) are relative to: the ground is supplied to alternating voltage converters 35-37 into a logic signal with settings for 0.2if and to the main inputs of keys 43-45, and The neutral is supplied to two converters 47 and 48 (Fig. 3) S of an alternating voltage into a logic signal with settings for voltage Um and 0.8 U, respectively. The voltage setting of converter 49 is equal to 0.005 and, p. If the input voltages of the converters are less than the voltage of the settings, then their output signals are equal to a logical zero, exceeding: the voltage of the settings to a logical one. The selected settings provide: change: the output signal of one of the converters 35-37 only when a single-phase ground fault occurs in the electric network of the LEPP) or the voltage disappears at one of the phases (phase out - OF); output signals of converters 47 and 48, which allow to form a control command for setting the compensation system during the burning of the intermittent from the ground arc, when the neutral voltage U changes almost from the phase value to zero; the output signal of the converter .4 at the occurrence of a metal single-phase closure to. the earth. The signals B from the inverted outputs of the drivers 35 - 37 are fed to the inputs of logical elements And of the phases of the same name (38-40, respectively, and to the inputs of the logical element SH and the signals F from the non-inverted outputs to logical elements of the lagging and advanced phases. Such a connection circuit in normal the mode of operation of the electrical network ensures the prohibition of logical elements And from converters of the same phases, and in the event of a single-phase earth fault or phase failure, the resolution for the logical element of the damaged phase and confirmation the prohibition for logical elements of healthy phases. In normal mode (HP), the signal Z (Fig. 2) at the output of the logical element OR 41 is equal to a logical zero, and when a single-phase ground fault occurs or a phase break occurs, it immediately becomes equal to a logical one. from the aperiodic ground fault current component, which distorts the information about the compensation setting, a time block 42 is used, which ensures the delay of the Z signal for a time equal to 0.2-0.5 s. When signal Z becomes equal to a logical one, prohibition 1 is lifted at the fourth input of the logical element I of the faulty phase and at its output a signal appears, opening the corresponding key (one of 43, 44, 45), so that at the output of amplifier 46 is the voltage of the faulty phase Ui in analog form. To separate the fundamental harmonic U of the Un signal, a fundamental frequency filter 50 is used (Fig. 3). The signal N (Fig. 3) on the non-inverse output of the converter 47 in the normal mode is equal to logical zero. When the voltage exceeds 0.2 Um, it becomes equal to a logical one. Similarly, the signal K is changed at the non-inverse output of the converter 48, but when the neutral voltage Ujj is above 0.8 Ug ,. The signal M at the non-inverse output, converter 49 becomes logical zero, when the voltage U, the damaged phase becomes less than 0.005 U With these values of voltage U, the information about the compensation setting may be distorted due to the smallness of the signal itself. To form signals characterizing certain states of the electrical network and which are used to control individual functional channels (blocks of the compensation system), the logical elements OR 52, AND 53 55 and AND-NOT 56 are used, to the inputs of which certain combinations of logic signals ( Fig. 3). To detect the normal mode, an AND 53 logic element is used, the inputs of which are fed to the logical signals Z and N. In the normal mode, these signals are equal to logical units, hence, and. the output signal H of the logical element And 53 will be equal to the logical unit (Fig. 4). Similarly, for detecting a single-phase earth fault through a transient resistance, an AND 54 logic element is used, to the two inputs of which logical signals K and M are supplied (its output signal is E); the transient during the burning of an intermittent grounding arc uses a logical element. And 55, to the two inputs of which logical signals N and K are fed (its output signal is D), and the metal single phase closure and phase loss first use the logical element OR 52, logical inputs Z and N (its output signal L) are fed to the two inputs. Next, the signal L together with the logical signal M is fed to the inputs of the logical element I – W 56, the output signal of which is R. Thus, the signal value will be equal to logical Dinits roofing in normal network operation (Ug40,2 Urn). The signal E will have the value of a logical unit only in the mode of stable single-phase closure through a small resistance (i.o.B. and ,,; 0,2. 0,005 u). T g E Signal D will have the value of a logical unit only in transient mode (0.8 UQ, UQ 0,,). The signal P will be the value. logical zero only in two modes: with a metallic single-phase short circuit to earth (, 8 Um, and .0.005 Uqj) and with a single break., T. from the phases, the received logical signals HE, D and P are then used in the automatic compensation system. The reactor control unit 4 operates as an integrating device. When a sinusoidal signal (voltage) arrives from the transformer 3 at its input, it is converted into square pulses using a square pulse generator 64. The received 1 pulses are divided by a divider 65 and, through one of the logic elements AND 58 or 66, direct coal pulses of reduced frequency affect the input of the direct counting of the reversing counter 59. The latter changes its state. Through the decoders 60 62 and the driver 63, the signals are fed to the output of the control unit of the receptor. They switch the keys of the arc suppressor reactor, as a result of which its inductance is changed. For example, if the pulse counter 59 is operated on addition, then the inductance of the arcing reactor increases, and if it is output, then the inductance of the reactor decreases. The counting direction of the reversible pulse counter 59 is determined by the state of the trigger 57 of the direction. When the state of the specified trigger changes, the input pulse changes the counting direction of the reversible counter 59. In the case when the reversible counter 59 reaches one of its limit states, the limiter 67 will block the passage of pulses through the AND 58 logic elements. and 66, so the inductance of the reactor will not change. When the state of the trigger 57 changes, the prohibition by limiter 67 is removed and the reversible counter 59 will again count the pulses (but in a different direction). When the compensation is detuned, the direction trigger 57 is in the state corresponding to the size of the compensation setting, and causes the reactor inductance to change in the direction of resonance tuning. In the resonant adjustment of compensation, the direction trigger 57 will be reversed periodically, and a self-oscillating mode will occur near the resonant tuning point in the system. The shaper pulses 25 and 31 of the short pulses to the front and rear edges are intended to form short pulses on the front and rear edges of square signals. They consist of two well-known short pulse shapers (on the leading and trailing edges), the output signals of which pass through the additional logic element I. Shapers serve to increase the information in one period of time (for example, during the industrial frequency) by two times. The device works as follows. In the normal network mode, the network mode determining unit 34 outputs zero signals E, D and a single signal H, which closes the second key 16. The inputs of the filter 17 and the phase shifter unit 13 are respectively supplied with the neutral voltage U0 and the reference voltage U, as which uses one of the linear stresses taken from the NTMI. The phase-sensitive element 15 adjusts the arc-quenching reactor 2 in phase between the voltages indicated. The resonant tuning corresponds to the zero angle between the voltages Uj, and UQ. When a single-phase short to ground through a small resistance, the network mode determination unit 3 outputs a zero signal H, D and a single signal E. Accordingly, the key 10 is closed, the key 16 is weakened, and the phase-sensitive element 9 is applied to the phase-sensitive element 9 F-. Zy U-, from the first output of the phase selection unit 6 and the neutral voltage U from the transformer 5 voltage. Thus, in the stable single-phase ground-fault mode, the arc-suppressing reactor 2 will be adjusted in phase between the voltages indicated. With resonant tuning, the angle between the voltages and and will be zero. If this causes a single-phase metallic earth fault in the network and the voltage JJj becomes less than 0.5%, then the signal P at the output of block 34 will become zero and ensure the prohibition of the operation of the reactor control unit 4, rum. The latter will remember the previous setting. As a result, the inductance of the reactor 2 will not change. When a single-phase closure to earth through an intermittent arc, the signals H 1 110 and E at the output of block 34 will be zero, and the signal D will become equal to logical one and, accordingly, the keys 10 and 16 will open and the key 29 will close. The input of the corresponding channel (blocks 19–33) will receive the neutral voltage U, and the phase voltage of the damaged phase U through one of the keys 19–21. This key is turned on by the corresponding output signal of the damaged phase selection unit 6. When signals U and and pass through zero, short pulses are formed, which are missed by counters 33 and 27, respectively. Depending on the ratio of the frequencies f and fp of the indicated voltages, one of the counters 33 or 27 calculates to the specified number and sets RS to the appropriate state trigger 29. At the same time, it will reset the zero state of another counter. The signal from the RS flip-flop output through the switch 29 will go to the control input of the reactor control unit 4 and will provide a change in its inductance in the direction of resonance tuning. With this, the frequency f will change as the frequency f, of the network. c. Resonant compensation adjustment corresponds to the equality of frequencies. The use of the device increases the reliability of the network operation.

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Claims (2)

1. DEVICE FOR COMPENSATING A CAPACITIVE SINGLE-PHASE CIRCUIT CIRCUIT TO EARTH, containing a discrete arcing reactor, one terminal of which is connected to the neutral of the transformer connected to the network, and the second terminal Via the current transformer - * to the ground, the damaged phase selection block connected ~ to the phase windings voltage transformer voltage, connected in series connected to the zero-sequence winding of the voltage transformer, the first phase-shifting unit, the first square-wave driver and a sensing element connected in series with the first output of the selection block. the damaged phase is the first main frequency filter and the second square-wave pulse generator, the output of which is connected to the second input of the first phase-sensitive element, the second phase-shifting unit connected to the phase voltage winding of the voltage transformer. , the third driver of rectangular pulses, the second phase-sensitive element, connected in series connected to the winding the left sequence of the voltage transformer, the second main frequency filter, the fourth square-wave pulse generator, the output of which is connected to the second input of the second phase-sensitive element, as well as the reactor control unit connected to the current transformer by one input, characterized in that, in order to improve the tuning accuracy and reliability of the network, a network mode determination unit, six keys, an amplifier connected in series, a third phase-shifting unit, a fifth rectangular driver and pulses, the first driver of short pulses to the leading and trailing edges, the first logic element And ,, the first pulse counter, RS-flip-flop, the sixth driver of rectangular pulses connected in series, the second driver of the short pulses to the leading and trailing edges, the second logic element And, the second counter pulses, the output of which is connected to the second input of the RS-trigger, and the outputs of the phase-sensitive elements are connected to the control input of the reactor control unit, respectively, through the first and second keys, the following three keys are connected to the phase voltage winding of the voltage transformer, their, outputs are connected to the input of the force SU 1197001, and the control inputs are respectively connected to the second, third and fourth outputs of the faulty phase selection unit, the sixth key is connected between RS -trigger and control input of the reactor control unit, and the control inputs of the first, second and sixth keys are connected to the corresponding outputs of the network mode determination unit, the output of the first counter is connected to the installation input of the second counter, and the output of the second about the counter - with the installation input of the first counter, the first and fifth outputs of the faulty phase selection unit are connected respectively to the second and third inputs of the network mode determination unit, the fourth output of which is connected to the blocking input of the reactor control unit, the first input of the network mode determination unit and the input of the sixth shaper rectangular pulses are connected to the zero-sequence voltage winding of the voltage transformer. 2. The device pop. 1, characterized in that the network mode determination unit comprises three converters of alternating voltage into a logic signal with voltage settings, a main frequency filter, a logical element NOT, an logical element OR, three logical elements AND and one logical element YNE, moreover, to the first input of the determination unit in the network mode, the inputs of the first two converters of AC voltage to a logical _x signal are connected, the input of the filter of the fundamental frequency is connected to the second input, a. to the third input are connected the input of the logical element NOT and the first input of the logical element OR, the output of the logical ele- ment is NOT connected to the first input of the first logical element AND, the non-inverse output of the first converter of alternating voltage into a · logical signal is connected to the second input of the logical element OR and to the first input of the third logical element And, and its inverse input is connected to the second input of the first logical element And, The inverse output of the second AC-to-logic converter is connected to the first input of the second logical element And, and the inverse output is the second input of the third logical element And, non-inv The third output of the third AC-to-logic converter is connected to the first input of the AND gate, and the inverse output to the second input of the second AND gate, the output of the OR gate is connected to the second input of the AND gate, the outputs of the first, second, and third logical elements AND and a logical element AND are NOT connected respectively to the four outputs of the network definition-mode block.