SU1050031A1 - Device for determining electric mains condition - Google Patents

Abstract

A DEVICE FOR DETERMINING THE ELECTRIC NETWORK MODE, containing, respectively, four voltage transducers into a logic signal with the specified voltage settings, three And elements, the first inputs of which are connected to inverted outputs of alternating voltage converters into a logic signal of the same phase, and the second and third inputs - with direct outputs of alternating voltage converters with responsibly advancing and lagging phases, three keys, the main input of each of which is connected to the voltage sensor of the corresponding phase relative to the earth, the control input to the output of the logical element AND of the phase of the same name, and the outputs of all the keys are connected to the measuring device, logical element OR , characterized in that, in order to expand the functional and rational possibilities by isolating a metal single-phase ground fault, an incomplete phase mode and a phase break, the logic signals connected to the forward output are entered into it element OR the first time delay block, the output of which is connected to the fourth inputs of the first three logical elements AND, connected in series to the fourth converter of alternating voltage into a logical signal, the second time delay block and the logical element realizing the function of equivalence, the second input of which is connected to the direct the output of the OR gate, connected in series to the key outputs of the key filter of the main frequency and the fifth variable voltage converter and into a logic signal with a preset voltage setting, as well as additional logic elements And and five actuators, three of them. the inputs of the OR gate are connected respectively to the inverse outputs of the first three alternating voltage converters, the first input of the fourth AND logic element is connected to the forward output of the OR logical element, the second (L input - to the inverted output of the fifth alternating voltage converter, and inverse output — with the first input of the fifth logical element I, the second of which is connected to the direct output of the logical element realizing the function of equivalence; the first input of the sixth logical element AND connected to the output of the first logic element I, the second input to the inverse output of the fifth AC converter 01 of the alternating voltage, and the output to the first resistor, the second control element connected to the forward output of the fifth AC converter, the first input the seventh logical element I is connected to the direct output of the fourth logical element I, the second input to the output of the second time-delay unit, and the output to the third control element, the first input of the eighth logical element TA and is connected to the inverted output of the OR gate, the second input - to the output of the fourth alternating voltage converter, and an output - to the fourth actuating element, a first input of a ninth logic

Description

element AND is connected to the direct output of the logical element OR, the second input - to the inverse output of the logical element,

implements the function of equivalence, and the output - to the p executive element.

The invention relates to electrical engineering, in particular, to the field of electrical networks, and can be used to indicate the modes of the electrical network, as well as in devices for automatically compensating for single-phase earth-fault current, in automatic devices for bypassing the damaged phase, and in protecting electrical networks.

A device for determining a faulty phase in a single-phase short circuit to earth in a network with an insulated neutral is known, which contains a zero-sequence voltage filter, maximum-voltage elements, and And 1 logic elements.

The disadvantages of this device are that it does not distinguish and responds to the metal ground fault mode and asymmetrical modes arising in the electrical network.

A device for protection against an asymmetrical mode of an electrical network with an isolated or compensated neutral is known, containing alternating voltage into a logic signal transformers connected to each of the mains and mains phases of the network, three AND logical elements, an OR logical element and a logic element implementing the equivalence function 2. .

However, this device also does not detect the metal single-phase ground circuit and does not distinguish the initial single-phase ground circuit in order to detune from it and eliminate false information that may occur during this period.

The closest technical solution to the invention is a device for determining a damaged phase in a single-phase short circuit to earth, containing, respectively, four voltage measurement units, three logical elements AND, the inputs of each of them connected to the supply voltage of the network with respect to ground and neutral voltage. connected to the outputs of all four voltage measurement units, three keys, the main input of each of them is connected to the voltage relative to the earth of its phase, the control input is connected to the log eskim AND gate

the same phase, and the output - with its input adder, as well as the logical element OR and the executive body 3.

A disadvantage of the known device is that it does not reveal the metal single-phase ground circuit and the asymmetrical modes.

The purpose of the invention is to extend the functionality of the device by

separation of metallic single-phase ground fault, incomplete phase mode and phase failure.

The goal is achieved by the fact that the device for determining the mode of the electrical network, containing, respectively, four sensors of alternating voltage to logic converters connected to the sensors of the voltage of the network relative to the earth and to the sensor of the neutral voltage of the network

0 signal with specified settings for voltage, three logic gates And, the first inputs of which are connected to the inverse outputs of converters of alternating voltage into a logic signal of the same phases, and the second and third inputs - to direct

5 outputs of alternating voltage converters leading and lagging phases respectively, three keys, the main input of each of which is connected to the voltage sensor of the corresponding phase relative to the earth, the control input to the output of the logic element AND of the same phase, and the outputs of all the keys are connected to the measuring device, and the logical element OR, entered connected to the forward output of the logic element OR the first block of time delay, the output of which is connected to the fourth inputs of the first three logical elements AND, connected in series connected to the fourth converter of alternating voltage into a logic signal the second block of exposure

0 time and a logical element that implements the function of equivalence, the second input of which is connected to the direct output of the OR logic element, connected in series to the outputs of the keys of the main frequency filter and the fifth alternator of the alternating voltage into a logical signal with a predetermined voltage setting, and Also, there are additional AND logic elements and five executive elements, and three inputs of the OR logic element are connected respectively to the inverse outputs of the first three converters n variable voltage, the first input of the fourth logical element AND is connected to the direct output of the logical element OR, the second input - to the inverse output of the fifth transformer of the alternating voltage, and the inverse output to the first input of the fifth logical element AND, the second input of which is connected to the direct output of the logic element that implements the function of equivalence, the first input of the sixth logic element AND is connected to the output of the fifth logical element AND, the second input - to the inverse output of the fifth converter of variable voltage voltage, and an output - to the first executive element, a second actuating element connected to the direct output of the fifth AC voltage converter. the first input of the seventh AND gate is connected to the forward output of the fourth AND gate, the second input to the output of the second time delay block, and the output to the third control element, the first input of the eighth AND gate is connected to the inverse output of the OR gate, the second input - to the output of the fourth variable voltage converter, and the output to the fourth control element, the first input of the ninth AND logic element is connected to the forward output of the logic element OR, the second input - to the inverse output of the logic element that implements the function of equivalence, and the output - to n tOm executive element. In practical schemes, the output signals of the keys can be fed to an adder with three inputs, implemented, for example, on a summing amplifier. Relay indicators can be taken as actuators. FIG. 1 shows a functional diagram of the device; in fig. .2 - stylized stress diagram. The device circuit includes converters 1-3 of variable voltage to logical. signal with voltage setting, keys 4-6 converter 7 alternating voltage into logic signal with voltage setting, logic elements AND 11 OR, time delay unit 12, measuring device 13, time delay unit 14, logic element 15 : realizing the function of equivalence, fundamental frequency filter 16, variable voltage converter 17 to logic signal with voltage setting, AND 18-20 logic elements, executive elements 21, 22, And 23 logic element, executive element 24, logical The element 25, the actuator 26, the logic element 27, the actuator 20. The phase voltage of the network relative to the earth is supplied to alternating voltage transformers 1-3 into a logic signal, to the main inputs of switches 4-6, and the neutral voltage is applied to inverter 7. Transducers 1; 3 have a voltage setting of 0.05–0.2, and converter 7 has a setpoint of 0.3. If the input voltages of the transducers are less than the set voltage, their output signals are equal to logic zero, if the setpoint is exceeded, the logical unit . Selected options provide a change in the output signal of one of the transducers 1, 2 and 3 only when a single-phase ground fault occurs in the electrical network or the voltage disappears at one of the phases, and at the output of the transducer 7 at any corresponding increase in voltage to the neutral. The signals F from the inverted outputs of the converters 1-3 are fed to the inputs of logical elements AND of the phases of the same name (respectively 8-10) and to the inputs of the logical element OR 11, and the signals F from the direct outputs to the logic elements of the lagging and leading phases. Such a wiring diagram in the normal operation of the electrical network ensures the prohibition of logical elements And from converters of the same phase, and in the event of a single-phase earth fault or loss of voltage during a phase (phase failure) - a resolution for the logical element And a damaged phase and confirmation of the prohibition for logical elements And healthy phases. In normal mode (HP), the signal Z (Fig. 2) at the output of the logic element OR 11 is equal to a logical zero, and when a single-phase earth fault (RPZ) or phase failure (RP) occurs, it immediately becomes equal to the logical one; To offset the aperiodic component of the earth fault current, a time delay block 12 is used, which provides a delay of signal Z by a time tj equal to 0.2-0.5-s. When the signal Zt becomes equal to a logical one, the prohibition on the fourth input of the logic element AND the faulty phase is removed and a D signal appears at its output, which opens the corresponding key, so that the voltage of the damaged phase Uj in analog form appears at the output of this key which is fixed by the measuring device 13. The output signal N of the converter 7 in the normal mode (HP) is equal to a logic zero, and in the case of a single-phase short circuit to earth (RPZ) or incomplete-phase modes of the electrical network (NPFR) - a logical unit tse A time delay tz 0.5-1s, created by the time delay unit 14, is introduced for the detuning from transients after the elimination of a single-phase closure to earth. Signals Z and N are fed to the input of a logic element 15 implementing the function of equivalence, i.e. its output signal L is equal to logical one, when both of its input signals are equivalent (both are equal to logical one or logical zero), and equal to logical zero, when one of the signals is equal to logical one, and the second is logical zero. Thus, the signal L is equal to a logical zero immediately after the elimination of the single-phase ground fault during the time tz, in the case of non-full-phase modes and phase breaks. When a metal single-phase ground fault (MFD) occurs, the residual voltage at the damaged phase of the ultrasonic becomes close to zero, which leads to a distortion of information about this voltage. This may lead to the false operation of automatic devices. In order to detect this mode, the voltage Us is fed to the fundamental frequency filter 16, which delays higher harmonics and passes an input voltage Uj of the main harmonic to the input of the variable voltage converter 17 into a logic signal with a voltage setting. Converter 17 has a voltage setting of 0.1-0.5% of UV. The output signal M of the converter 17 is equal to a logical unit, only with a single-phase short to earth (OZZ) through a transient resistance, when, 1-0.5% Ucfj, in all other cases - to a logical zero. To isolate the signal K in the case of a metallic ground fault and a phase break, an AND 18 logic element is used, the first input of which is supplied with the signal Z and the second signal M from the inverted output of the converter 17. To obtain the signal P carrying information about the appearance of the metal short circuit the earth (MOZZ), liquidation of the earth fault, non-phase modes (NPFR) and phase breaks (RP), uses an AND 19 logic element, the first input of which is given a signal L, and a second signal K is fed from an inverted output of the AND 18 logic element. To in The transducer 17's logic output and the AND 19 logic element are connected to the AND 20 logic element inputs. The M signal is sent to one last input, and the P signal is fed to the other. At the output of the 20 element, a signal (logical unit) is output on the normal network mode and goes the first actuator 21. A single-phase earth fault signal through the resistance appears at the forward output of the converter 17 and goes to the second actuator 22. To the forward output of the AND 18 logic element and to the output of the time delay block 14 The inputs of the logic element are And 23. At one input of the latter, a signal K is received, at the other - a signal N, and the output is a signal of a metallic single-phase short to earth, which is fed to the third control element 24. To the inverse output of the logic element OR 11 and to the output of the converter 7, the inputs of an AND 25 logic element are connected. At one input, it receives a signal Z, at the second - a signal N, and at the output a signal about an incomplete-phase mode is output, and is fed to the fourth stage: an additional element 26. output logic ENTOR 11 and the inverse output of the logic element 15, which implements the function of equivalence, are connected the inputs of the logic element AND 27. At one input, it receives a signal Z, at the other - the signal L, and at the output a signal about phase failure is detected and The second executive element 28. The proposed device will improve the reliability of information on the state of the electrical network, will determine the correct operation of the automatic control systems, thereby improving the transients in the electrical network and increase its reliability.

HP 033 MQJ3 053 HP HP 0 HP

2

Claims (1)

DEVICE FOR DETERMINING THE ELECTRIC NETWORK MODE, containing four AC converters into a logical signal with preset voltage settings, three logical elements And, the first inputs of which are connected to the inverted outputs of the AC converters, respectively connected to the voltage sensors of the network phases relative to the ground and to the voltage sensor of the neutral of the network voltage in the logical signal of the same phases, and the second and third inputs - with direct outputs of AC voltage converters, respectively of the leading and lagging phases, three keys, the main input of each of which is connected to the voltage sensor of the corresponding phase relative to the ground, the control input is to the output of the logical element AND of the same phase, and the outputs of all keys are connected to the measuring device, and the logical element is OR, different the fact that, in order to expand functional, functional capabilities by highlighting a metal single-phase circuit on. ground, in-phase mode and phase failure, it contains the first time delay unit connected to the direct output of the logic element OR, the output of which is connected to the fourth inputs of the first three logic elements AND, sequentially connected to the fourth AC-to-logic converter a time delay unit and a logic element that implements the equivalence function, the second input of which is connected to the direct output of the OR logic element, connected in series with the main frequency filter and the fifth AC-to-logic converter to a logic signal with a given voltage setting, as well as six additional AND logic elements and five actuating elements, three inputs of the OR logic element respectively connected to the inverse outputs of the first three AC converters voltage, the first input of the fourth logical element AND is connected to the direct output of the logical element OR, the second input is with the inverse output of the fifth converter voltage, and the inverse output is connected to the first input of the fifth logical element AND, the second input of which is connected to the direct output of the logic element that implements the equivalence function, the first input of the sixth logical element And is connected to the output of the fifth logical element And, the second input to the inverse output of the fifth AC voltage converter, and the output to the first actuator, the second actuator connected to the direct output of the fifth AC converter, the first input of the seventh The logical element AND is connected to the direct output of the fourth logical element AND, the second input is to the output of the second time delay unit, and the output is to the third actuator, the first input of the eighth logical element AND is connected to the inverse output of the OR logic element, the second input is to the output of the fourth AC voltage converter, and the output to the fourth actuator, the first input of the ninth logical SU „„ 1050031 of the AND element is connected to the direct output of the OR gate, the second input to the inverse output of the logic element that implements the equivalence function, and the output to the fifth actuator. *