RU40689U1 - DEVICE RESERVE LINE WITH TRANSFORMERS ON BRANCHES - Google Patents

Abstract

The device is designed for backup protection of lines with transformers on the branches. The essence of the device is the control of signals proportional to the modules of the currents of the reverse, direct, zero sequence, voltages of the reverse and direct sequence, phase relations between currents and voltages of the forward and reverse sequence, orthogonal components of the current of the direct sequence and their increments, increments of the current of the direct sequence taking into account the previous direct current sequences in normal load mode.

Description

The utility model relates to electrical engineering and can be used for backup relay protection of overhead and cable lines having branches with transformer substations.

A device is known [A.S. USSR 1737611, MKI H02H 7/28. Kuznik Yu.S. Device for backup line protection with soldering transformers. Publ. 10/17/89, Bull. No. 20] built on the basis of the reverse sequence current relay, power direction relay and direct sequence current relay, increment relay and direct sequence current decay relay.

The disadvantages of this device are a failure in the short-term existence of an interphase short-circuit and insufficient speed of the reverse sequence current relay, an increase (decrease) in the direct sequence currents also occurs when the motors start up (self-start) when the line is switched on in the automatic reclosure cycle, which must be taken into account when choosing settings and this limits his sensitivity.

A device is known [A.S. USSR 1361668, MKI Н02Н 3/08. Kletsel M.Ya., Kopbaev M.A., Nikitin K.A., Polyakov V.E. Device for redundant current protection of a dead end line with branches from an interphase short circuit. - Publ. 11/23/87, Bull. No. 47.] For backup current protection of a dead-end line with branches from an interphase fault, which consists of a linear current-to-voltage converter, a multi-bit ADC, a subtractor, a shift register, a comparison unit, a set point, the first, second logical elements, OR NOT, the first - the fourth time elements, the first to the third logical elements AND, the MEMORY element, a clock pulse generator, an executive body, a line switch, a voltage-to-voltage converter, an amplifier-limiter, a low-pass filter, reobrazovatelya reactive current component.

The disadvantages of this device are the need for detuning from the inclusion of the line in time, a decrease in sensitivity in the presence of a powerful motor load on the branches of the line.

A device for adaptive backup protection of a radial line with branches (prototype) [Certificate for Utility Model No. 9099 of the Russian Federation 6N02NZ / 08

Nagay V.I., Sarah S.V., Chizhov K.V., Kotlov M.M. Adaptive radial line back-up protection device with branches. - Publ. 1/16/99, Bull. No. 1], containing voltage and current sensors, reactive and active current component converters, phase comparison organs, brake signal generation organs, subtractors, first and second threshold elements, a logic block as a part of OR or I logic elements, a zero-sequence current organ as a part zero sequence current filter and third threshold element, response time delay element, output organ.

The disadvantages of this device are applicability only for radial lines, reduced sensitivity to fault behind transformers in modes with significant active-capacitive load of the line and at high active load currents, reduced sensitivity to two-phase fault behind transformers of branch substations.

The technical task of the utility model is the backup relay protection of branch transformers. The technical result is to increase the sensitivity and selectivity of the backup relay protection of branch transformers, the applicability of the backup relay protection of branch transformers both for radial and double-sided lines.

The technical problem is solved using a backup line protection device with transformers on the branches, containing current sensors and voltage sensors, a zero-sequence current organ, a reactive component converter, an active component converter, a phase comparison body, a brake signal generating body, a subtractor, a first threshold element, a second threshold element, logic block, time delay element, output organ, signal processing unit, trigger element of asymmetric components, trigger organ current increments, orthogonal component increment trigger element, orthogonal component increment organ, blocking element, current memory element, orthogonal component memory element, negative sequence current element, negative sequence power directional element, negative sequence voltage organ, direct sequence voltage organ, reactive voltage output, reactive converter output component is connected to the first input of the subtractor, the output of the converter of the active component is connected to the first the input of the body of the formation of the brake signal, the output of the phase comparison body is connected to the second

the input of the brake signal generating organ, the output of the brake signal generating organ is connected to the second input of the subtracter, the output of the subtractor is connected to the input of the first threshold element, the output of the first threshold element is connected to the first input of the logic unit, the output of the second threshold element is connected to the fourth input of the logic unit, organ output zero sequence current is connected to the seventh input of the logic unit, the logic unit, the time delay element and the output organ are connected in series, the outputs of the current sensors and the sensor The voltage s are connected by the inputs of the signal processing unit, the first output of the signal processing unit is connected to the input of the zero-sequence current element and the first input of the starting element of the asymmetrical components, the output of the starting element of the asymmetric components is connected to the fifth input of the logic unit and the third input of the current memory element and the third input of the memory element orthogonal components, the second output of the signal processing unit is connected to the second input of the starting organ of the asymmetric components, the input of the current sequence and the first input of the negative direction power direction control element, the output of the negative sequence current element is connected to the tenth input of the logic unit, the output of the negative sequence power direction organ is connected to the eleventh input of the logic block, the third output of the signal processing block is connected to the first inputs of the phase comparison organ, converter a reactive component, an active component converter, a starting increment element of a current, a blocking element, a current memory element, the input of the second threshold organ, the fourth output of the signal processing unit is connected to the second inputs of the phase comparing organ, the converter of the reactive component, the converter of the active component, the input of the direct voltage organ, the fifth output of the signal processing unit is connected to the second input of the negative direction power direction organ and the input of the voltage organ of the reverse sequence, the output of the phase comparison organ is connected to the eighth input of the logic unit, the output of the reactive converter the component is connected to the first input of the memory element of the orthogonal components, the second inputs of the starting organ of the increment of the orthogonal components and the organ of the increment of the orthogonal components, the output of the converter of the active component is connected to the second input of the memory element of the orthogonal components, the third inputs of the trigger of the organ of the increment of orthogonal components current memory element connected to the second inputs

the blocking body and the starting body of the current increment, the output of the starting body of the current increment is connected to the second input of the logic unit, the fourth input of the current memory element, the fifth input of the memory element of the orthogonal components, the output of the blocking body is connected to the first inputs of the starting body of the increments of orthogonal components and the increment organ of the orthogonal components , the output of the memory element of the orthogonal components is connected to the fourth inputs of the starting organ of the increments of the orthogonal components and the organ at orthogonal components, the output of the starting element of the increments of the orthogonal components is connected to the third input of the logic unit, the second input of the current memory element and the fourth input of the memory element of the orthogonal components, the output of the increment organ of the orthogonal components is connected to the sixth input of the logic unit, the output of the direct sequence voltage organ is connected to the ninth the input of the logic unit, the output of the negative sequence voltage organ is connected to the twelfth input of the logic unit.

In FIG. a structural diagram of the backup line protection device with transformers on the branches is presented, where DT1, DT2, DT3 are current sensors 1-3, DN1, DN2, DN3 are voltage sensors 4-6, OTNP is a zero-sequence current organ 7, ORS is a reactive component converter 8, PAS - active component converter 9, OSF - phase comparing authority 10, OFTS - brake signal generation organ 11, HF - subtractor 12, PE1 - first threshold element 13, PE2 - second threshold element 14, BL - logic block 15, EVV - time delay element 16, VO - output organ 17, BOS - signal processing unit 18, PONS — trigger element of asymmetric components 19, POPT — trigger element of increment of current 20, POP — trigger element of increments of orthogonal components 21, OPOS — increment organ of orthogonal components 22, BO — blocking organ 23, EPT — current memory element 24 , EPOS - memory element of orthogonal components 25, OTOP - negative sequence current organ 26, ONMOP - negative sequence power direction organ 27, ONOP - negative sequence voltage organ 28, ONOP - direct last voltage organ sequence 29, the output of the transducer of the reactive component 8 is connected to the first input of the subtractor 12, the output of the transducer of the active component 9 is connected to the first input of the body of the formation of the brake signal 11, the output of the organ of comparison of the phases 10 is connected to the second input of the body of the formation of the brake signal 11, the output of the body of the formation of the brake signal 11 is connected to the second input of the subtractor 12, the output

a subtractor 12 is connected to the input of the first threshold element 13, the output of the first threshold element 13 is connected to the first input of the logic block 15, the output of the second threshold element 14 is connected to the fourth input of the logic block 15, the output of the zero-sequence current organ 7 is connected to the seventh input of the logic block 15, the logic unit 15, the time delay element 16 and the output organ 17 are connected in series, the outputs of the current sensors 1-3 and voltage sensors 4-6 are connected by the inputs of the signal processing unit 18, the first output of the signal processing unit 18 is connected to the input ohm of the zero-sequence current element 7 and the first input of the starting element of the asymmetrical components 19, the output of the starting element of the asymmetric components 19 is connected to the fifth input of the logic unit 15 and the third input of the current memory element 24 and the third input of the orthogonal component memory element 25, the second output of the signal processing unit 18 connected to the second input of the starting element of the asymmetric components 19, the input of the negative sequence current organ 26 and the first input of the reverse sequence power direction organ 27, the output of the negative sequence current organ 26 is connected to the tenth input of the logic block 15, the output of the negative sequence power direction organ 27 is connected to the eleventh input of the logic block 15, the third output of the signal processing unit 18 is connected to the first inputs of the phase comparing organ 10, reactive component converter 8 , the converter of the active component 9, the starting organ of the current increment 20, the blocking organ 23, the current memory element 24, the input of the second threshold organ 14, the fourth output of the signal processing unit 18 connected to the second inputs of the phase comparison organ 10, the converter of the reactive component 8, the converter of the active component 9, the input of the direct sequence voltage organ 29, the fifth output of the signal processing unit 18 is connected to the second input of the negative direction power direction organ 27 and the input of the negative sequence voltage organ 28, the output of the phase comparison organ 10 is connected to the eighth input of the logic unit 15, the output of the converter of the reactive component 8 is connected to the first input of the orthogonal memory element components 25, the second inputs of the starting element of the increments of the orthogonal components 21 and the element of the increment of the orthogonal components 22, the output of the converter of the active component 9 is connected to the second input of the memory element of the orthogonal components 25, the third inputs of the starting element of the increments of orthogonal components 21 and the increment organ of orthogonal components 22, the output current memory element 24

connected to the second inputs of the blocking body 23 and the trigger of the current increment 20, the output of the trigger of the current increment 20 is connected to the second input of the logic block 15, the fourth input of the current memory element 24, the fifth input of the memory element orthogonal components 25, the output of the blocking organ 23 is connected to the first the inputs of the starting organ of the increments of the orthogonal components 21 and the organ of the increment of the orthogonal components 22, the output of the memory element of the orthogonal components 25 is connected to the fourth inputs of the starting organ is incremented of the orthogonal components 21 and the increment organ of the orthogonal components 22, the output of the starting organ of the increments of the orthogonal components 21 is connected to the third input of the logic unit 15, the second input of the current memory element 24 and the fourth input of the memory element of the orthogonal components 25, the output of the increment organ of the orthogonal components 22 is connected to the sixth the input of the logic unit 15, the output of the direct sequence voltage organ 29 is connected to the ninth input of the logic unit 15, the output of the negative sequence voltage organ 26 is connected ene twelfth input logic block 15.

The device operates as follows, phase currents and voltages from current transformers and line voltage transformers are supplied to the inputs of current sensors 1-3 and voltage sensor inputs 4-6, current sensors 1-3 and voltage sensors 4-6 generate output signals proportional to the input currents and voltages so that the output signal levels allow you to work in the required accuracy class and not be damaged by the other elements of the device.

The signal processing unit 18 measures the modules and phase relations of phase currents and voltages, voltages and currents of the zero sequence, filtering the currents and voltages of the reverse, zero and forward sequences, find the phase relations between currents and voltages of the phase and direct, zero and reverse sequences.

The converter of the reactive component 8 generates a signal proportional to the reactive component of the direct sequence current according to expression (1).

where I _p is the reactive component of the direct sequence current;

I is the effective current value of the direct sequence;

φ is the angle between the current vector and the direct sequence voltage vector.

The transducer of the active component 9 generates a signal proportional to the active component of the direct sequence current according to expression (2).

where I _a is the active component of the direct sequence current.

The current memory element 24 stores the direct sequence current module in the previous normal mode. The memory element of the orthogonal components 25 stores the values of the active and reactive components of the current of the direct sequence, taking into account the sign in the previous normal mode. The increment organ of the orthogonal components 22 and the trigger organ of the increments of the orthogonal components 21 vector subtract the reactive and active components of the direct current current in the current and previous modes, generate a brake signal proportional to the increment of the active current component, subtract and compare the result with the response level according to the expressions (3 -5):

where ΔI _a is the increment of the active component of the direct sequence current;

I _a.p. - the active component of the direct sequence current in the previous normal mode.

where ΔI _p is the increment of the reactive component of the current direct sequence;

I _rp - reactive component of the direct sequence current in the previous normal mode.

where I ₂₁ and I ₂₂ are the magnitudes of the signals compared with the trigger thresholds of the trigger of the increments of the orthogonal components 21 and the increment of the orthogonal components 22;

k _t - braking coefficient.

The separation of the modes into the previous normal and emergency, prohibiting during emergency modes updating the contents of the memory elements of currents 24 and orthogonal components 25, is performed after the trigger

asymmetrical components 19, the starting organ of the increments of the orthogonal components 21 and the starting organ of the increment of the current 20. The blocking organ 23 prohibits the operation of the organ of the increment of the orthogonal components 22, if the direct sequence current in the current mode decreases relative to the direct sequence current in the previous normal mode above the operation level.

The trigger element asymmetrical components 19 is activated if the current of the negative sequence is greater than the current of the zero sequence and the level of operation.

The action of the bodies forming the brake signal 11, the subtractor 12 and the first threshold element 13 is similar to the action of the same elements of the prototype. The body of the formation of the brake signal 11 produces a brake signal proportional to the active component of the direct sequence current and the angle between the current voltage of the direct sequence, the subtractor 12 subtracts it from the signal of the proportional reactive component of the current of the direct sequence, the first threshold element 13 compares the output signal of the subtractor 12 with the response level .

The operation of the zero-sequence current organ 7 prohibits the operation of the device so that the device does not work unnecessarily when there is a short to ground on the power line.

The triggering of the second threshold element 14 inhibits the operation of the device so that the device does not work unnecessarily during interphase faults on the power line. Unlike the prototype, the second threshold organ 14 does not respond to the difference between the reactive component of the current and the brake signal, but to the direct current total current, which makes its operation less dependent on the phase relations between currents and voltages during short circuit on the line.

The direct sequence voltage organ 29 inhibits the action of the device when the direct sequence voltage disappears, so that sensitive circuits that respond to the orthogonal components of the current and their increments do not work false.

In the normal mode, the direct sequence voltage organ 29 is in the triggered state, the state of the blocking organ 23, the power direction direction of the reverse sequence 27 can be different, the rest of the organs are not triggered. All organs acting on the operation of the device are detached from

load conditions, start / self-start of a powerful electromotive load and the inclusion of the line in the reclosure cycle.

With interphase short-circuit on the line, and not behind protected transformers, the second threshold element 14 is activated, which prohibits the device from tripping, with close three-phase short-circuit, the operation of the device can also be prohibited by the action of a direct sequence voltage organ 29.

With single-phase short circuit in the network, the zero-sequence current organ 7 inhibits the operation of the device.

In case of two-phase fault, the negative sequence current element 26 is triggered behind the protected transformers. In this case, if the negative sequence voltage level is higher than the level of the negative sequence voltage organ level 28, then the device is enabled by the direction element of the negative sequence power 27, otherwise the direction is provided by the phase comparison organ 10, which measures the angle between the current and the voltage of the direct sequence and checks its presence in the operation zone. Thus, the device provides the direction of action in case of asymmetric damage and the possibility of application on lines with two-way power. The reverse sequence current appears in case of asymmetric faults and can be considered an emergency component, since in the load mode it is only a few percent of the line load current, its value does not depend on the group of transformer winding connections, on the contrary, the prototype will have a significant degree of sensitivity to two-phase short-circuit behind transformers depend on the connection group of the transformer windings and the shunt action of the load. For this reason, the sensitivity to the two-phase fault of the reverse sequence current organ will be higher than that of the prototype.

In case of three-phase short circuit, the first threshold element 13 and the increment organ of the orthogonal components 22, the trigger element of the increments of the orthogonal components 21 will work behind the transformers of the branch substations connected to the line 21. If the direct sequence current increases relative to the previous mode, the trigger of the current increment 20, if the damage starts with the asymmetry of the currents, the trigger element of the asymmetric components is also triggered 19. The operation of any of the trigger elements is prohibited a change (update) the current contents of the memory elements 24 and the orthogonal components 25, separating the alarm and the preceding

normal modes. The direction of protection for three-phase short-circuit behind transformers of branch substations connected to the line is provided by the working body of the phase comparison 10.

The response level selected for the detuning from the line on mode in the automatic reclosure cycle for the first threshold element 13 and the increment organ of the orthogonal components 22 is the same. Accordingly, the sensitivity of both organs during short-circuit behind the transformer in the absence of load currents in the previous mode is the same. However, during short circuit in the load mode, the presence of inductive load currents increases the sensitivity of the first threshold element 13, and the presence of active and capacitive load currents reduce the sensitivity of the first threshold element 13. On the contrary, the sensitivity of the increment organ of the orthogonal components 22 will depend on the nature and magnitude of the load current is much weaker , this measuring body will respond to the emergency component. By choosing different braking factors, it is possible to ensure that the first threshold element 13 and the increment organ of the orthogonal components 22 are mutually complementary. The increment organ of the orthogonal components 22 will have a higher sensitivity in the presence of capacitive load currents and at small angles of active-inductive load currents, the first threshold element 13 will have a higher sensitivity with significant inductive load currents. Since apart from the detuning from turning on the line in the automatic reclosure cycle, other conditions for choosing the response level will differ (conditions for accurate operation, and for the organ of increments of orthogonal components 22 there will also be a condition for detuning from the transition of one load mode to another load mode), then the high sensitivity zones of the first the threshold element 13 and the increment organ of the orthogonal components 22 partially overlap. Their orientation is ensured by the operation of the phase comparing body 10, and the precise operation of the converter of the reactive component 8 and the converter of the active component 9 by the direct sequence voltage organ 29. So that the increment organ of the orthogonal components 22 does not work unnecessarily when the capacitive load is disconnected, a blocking organ 23 is introduced that prohibits it work with a decrease in current relative to that observed in the previous mode over the threshold.

Block logic 15 works by the expression (6):

where F _cf - the output signal of the logic block;

F _ОНПП - output signal of the direct sequence voltage organ 29;

F _PE2 - the output signal of the second threshold element 14;

F _OTOP - the output signal of the current organ of the negative sequence 26;

F _ONOP - the output signal of the voltage organ of the negative sequence 28;

F _ONMOS - the output signal of the body direction power negative sequence 27;

F _OSF is the output signal of the phase comparison organ 10;

F _PE1 is the output signal of the first threshold element 13;

F _OPOS - the output signal of the organ increment orthogonal components 22;

F _PONS - the output signal of the trigger organ asymmetrical components 19;

F _POPT - output signal of the starting element of the increment of current 20;

F _POP - the output signal of the trigger of the increments of the orthogonal components 21. All triggering functions are logical signals that take on a value of logical unit and logical zero.

The time delay element 16 provides coordination of the main protection of the transformer and the device according to the response time, implements a delay of the device.

The output organ 17, when the device is triggered, provides a signal formation for influencing the line switching devices.

Thus, the use of the proposed device allows to achieve high sensitivity to interphase short-circuit behind transformers in the presence of active-capacitive load of the line, as well as better detuning from load conditions and, as a result, increased sensitivity to three-phase short-circuit behind transformers due to the adaptive formation of settings of measuring organs, expanding the scope of backup transformer protection on a double-sided line.

Claims (1)

A backup line protection device with branch transformers containing current and voltage sensors, a zero-sequence current element, a reactive component converter, an active component converter, a phase comparison body, a brake signal generating unit, a subtractor, first and second threshold elements, a logic unit, a holding element time, the output organ, the output of the converter of the reactive component is connected to the first input of the subtractor, the output of the converter of the active component is connected to the first the input of the brake signal generating body, the output of the phase comparison body is connected to the second input of the brake signal forming body, the output of the brake signal forming body is connected to the second input of the subtracter, the output of the subtractor is connected to the input of the first threshold element, the output of the first threshold element is connected to the first input of the logic unit, the output of the second threshold element is connected to the fourth input of the logic unit, the output of the zero sequence current element is connected to the seventh input of the logic unit, the logic unit, t time delays and the output organ are connected in series, characterized in that the signal processing unit, the trigger element of the asymmetrical components, the trigger element of the current increment, the trigger element of the increments of the orthogonal components, the increment organ of the orthogonal components, the blocking organ, the current memory element, the orthogonal memory element are additionally introduced constituents, negative sequence current organ, negative sequence power direction organ, negative sequence voltage organ, o direct sequence voltage generator, the outputs of current sensors and voltage sensors are connected to the inputs of the signal processing unit, the first output of the signal processing unit is connected to the input of the zero-sequence current organ and the first input of the asymmetrical component trigger element, the output of the asymmetric component trigger element is connected to the fifth input of the logic block and the third the input of the current memory element and the third input of the memory element of the orthogonal components, the second output of the signal processing unit is connected to the second input ohm of the trigger element of the asymmetric components, the input of the negative sequence current organ and the first input of the negative sequence power direction organ, the output of the negative sequence current organ is connected to the tenth input of the logic block, the output of the negative sequence power direction organ is connected to the eleventh input of the logic block, third output of the signal processing block connected to the first inputs of the phase comparison body, reactive component converter, active component converter, start the output organ of the current increment, the blocking organ, the current memory element, the input of the second threshold organ, the fourth output of the signal processing unit is connected to the second inputs of the phase comparison organ, the reactive component converter, the active component converter, the input of the direct sequence voltage organ, the fifth output of the signal processing unit is connected with the second input of the negative direction power direction control organ and the input of the negative sequence voltage organ, the output of the phase comparison organ inen with the eighth input of the logic unit, the output of the converter of the reactive component is connected to the first input of the memory element of the orthogonal components, the second inputs of the starting organ of the increment of the orthogonal components, the output of the converter of the active component is connected to the second input of the memory element of the orthogonal components, the third inputs of the starting organ increments of orthogonal components and organ increments of orthogonal components, output of the current memory element connected to the second inputs of the blocking body and the starting body of the current increment, the output of the starting body of the current increments is connected to the second input of the logic unit, the fourth input of the current memory element, the fifth input of the memory element of the orthogonal components, the output of the blocking body is connected to the first inputs of the starting body of the increments of orthogonal components and the increment organ of the orthogonal components, the output of the memory element of the orthogonal components is connected to the fourth inputs of the starting organ of the increments are orthogonal components and the increment organ of the orthogonal components, the output of the trigger of the increment of the orthogonal components is connected to the third input of the logic unit, the second input of the current memory element and the fourth input of the memory element of the orthogonal components, the output of the increment organ of the orthogonal components is connected to the sixth input of the logic unit, the output of the direct sequence voltage organ connected to the ninth input of the logic unit, the output of the negative sequence voltage organ is connected to the twelfth input of the log unit ki.