CN112834869A - Differential protection calibration system for large-length submarine cable in no-load state - Google Patents
Differential protection calibration system for large-length submarine cable in no-load state Download PDFInfo
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- CN112834869A CN112834869A CN202110029572.2A CN202110029572A CN112834869A CN 112834869 A CN112834869 A CN 112834869A CN 202110029572 A CN202110029572 A CN 202110029572A CN 112834869 A CN112834869 A CN 112834869A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/06—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric generators; for synchronous capacitors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
- H02P9/10—Control effected upon generator excitation circuit to reduce harmful effects of overloads or transients, e.g. sudden application of load, sudden removal of load, sudden change of load
- H02P9/12—Control effected upon generator excitation circuit to reduce harmful effects of overloads or transients, e.g. sudden application of load, sudden removal of load, sudden change of load for demagnetising; for reducing effects of remanence; for preventing pole reversal
Abstract
The invention discloses a differential protection calibration system for a large-length submarine cable in a no-load state. The system can automatically perform de-excitation operation on the generator when the voltage-stabilizing washing pipe analysis system body has power failure. The high-voltage cable differential protection verification system comprises a controller, a field suppression switch device, a high-voltage cable differential protection verification system body and a generator for providing power supply power for the high-voltage cable differential protection verification system body; the de-excitation switch device comprises a first main on-off control module and a de-excitation module; the input end of the first main on-off control module and the input end of the de-excitation module are respectively connected to the power output end of the generator; the output end of the first main on-off control module is connected to a 220KV bus. Simple structure, good safety and high reliability.
Description
Technical Field
The invention relates to a protection calibration system, in particular to a differential protection calibration system of a large-length submarine cable in a no-load state.
Background
At present, a high-voltage cable differential protection verification system in a no-load state is difficult to realize high-voltage cable differential protection verification under the no-load condition; and the power consumption of the high-voltage cable differential protection verification system is large, when the high-voltage cable differential protection verification system breaks down and is suddenly powered off, the suddenly-switched-off electric energy or the electric generator which provides power supply power for the high-voltage cable differential protection verification system generates huge impact, and even burns out the electric generator in serious conditions. Therefore, it is necessary to design a system which can realize the high-voltage cable differential protection verification under the condition of no load and is not easy to burn out the generator when the high-voltage cable differential protection verification system has power failure.
Disclosure of Invention
The invention mainly solves the defects in the prior art, and provides the differential protection verification system in the no-load state of the long submarine cable, which can realize the differential protection verification of the high-voltage cable under the no-load condition, can automatically perform the de-excitation operation on the generator when the high-voltage cable differential protection verification system body has power failure, protects the generator from being burnt out due to the power failure of the high-voltage cable differential protection verification system body, and prolongs the service life of the generator.
The technical problem of the invention is mainly solved by the following technical scheme:
a differential protection calibration system of a large-length submarine cable in a no-load state comprises a controller, a voice prompter, a communication module, a de-excitation switch device, a high-voltage cable differential protection calibration system body and a generator for providing power supply power for the high-voltage cable differential protection calibration system body;
the high-voltage cable differential protection verification system body comprises a startup and standby transformer circuit, wherein the startup and standby transformer circuit comprises a 220KV bus, a 220KV power cable differential protection CT1, a 220KV power cable differential protection CT2, a startup transformer, a 220KV power cable differential protection CT3 and a B startup transformer; one end of a 220KV power cable differential protection CT1 is connected to a 220KV bus, the other end of a 220KV power cable differential protection CT1 is connected to one end of a 220KV power cable, and one end of a 220KV power cable differential protection CT2 and one end of a 220KV power cable differential protection CT3 are connected to the other end of the 220KV power cable; the other end of the 220KV power cable differential protection CT2 is connected to the A backup transformer; the other end of the 220KV power cable differential protection CT3 is connected to a B starting-standby transformer;
the de-excitation switch device comprises a first main on-off control module, a second main on-off control module and a de-excitation module; the input end of the first main on-off control module, the input end of the second main on-off control module and the input end of the de-excitation module are respectively connected to the power output end of the generator; the output end of the first main on-off control module and the output end of the second main on-off control module are respectively connected to a 220KV bus; the voice prompter, the communication module, the control end of the high-voltage cable differential protection checking system body, the control end of the first main on-off control module, the control end of the second main on-off control module and the control end of the de-excitation module are respectively connected with the controller.
Preferably, the magnetic circuit breaker further comprises a first node and a second node, the first main on-off control module comprises a first left switch, a first relay and a first right switch, the second main on-off control module comprises a second left switch, a second relay and a second right switch, and the demagnetization module comprises a demagnetization left switch, a demagnetization relay, a demagnetization right switch and a demagnetization resistor;
the left end of the first left switch, the left end of the second left switch and the left end of the de-excitation left switch are respectively connected to the first node; the right end of the first left switch is connected to the left end of the first relay, the right end of the first relay is connected to the left end of the first right switch, and the right end of the first right switch is connected to the second node; the right end of the second left switch is connected to the left end of the second relay, the right end of the second relay is connected to the left end of the second right switch, and the right end of the second right switch is connected to the second node; the right end of the de-excitation left switch is connected to the left end of the de-excitation relay, the right end of the de-excitation relay is connected to the left end of the de-excitation right switch, and the right end of the de-excitation right switch is connected to the de-excitation resistor; the 220KV bus is connected to the second node; the power output end of the generator is connected to the first node;
the control end of the first left switch, the control end of the first relay, the control end of the first right switch, the control end of the second left switch, the control end of the second relay, the control end of the second right switch, the control end of the de-excitation left switch, the control end of the de-excitation relay and the control end of the de-excitation right switch are respectively connected with the controller.
Preferably, the demagnetization control of the demagnetization switch device is as follows:
setting the disconnection reaction time length required by the first main on-off control module from the time when the first main on-off control module sends a first disconnection command to the time when the first main on-off control module completes the disconnection action as T1, setting the disconnection reaction time length required by the second main on-off control module from the time when the second main on-off control module sends a second disconnection command to the time when the second main on-off control module completes the disconnection action as T2, and setting the conduction reaction time length required by the demagnetization module from the time when the demagnetization module sends a demagnetization conduction command to the time when the demagnetization module completes the conduction action as T3; setting the time required by the de-excitation switching of the generator system corresponding to the de-excitation switch device as H;
when the first main on-off control module is switched on, the second main on-off control module is in an off state, and the value of the off reaction time length T2 of the second main on-off control module and the value of the on reaction time length T3 of the de-excitation module are detected under the control of the controller; calculating the time difference H2 between the conduction of the de-excitation module and the disconnection of the second main on-off control module, wherein H2 is | T2-T3| ≦ H; when next demagnetization operation is to be carried out under the condition that the second main on-off control module is switched on, if T2-T3 is more than or equal to 0, the controller sends a demagnetization switching-on instruction to the demagnetization module within H2 time after the controller sends a second switching-off instruction to the second main on-off control module; if T2-T3 is less than 0, the controller needs to send a de-excitation conducting instruction to the de-excitation module within H2 time before the controller sends a second turn-off instruction to the second main turn-on and turn-off control module;
when the second main on-off control module is switched on, the first main on-off control module is in an off state, and the value of the off reaction time length T1 of the first main on-off control module and the value of the on reaction time length T3 of the de-excitation module are detected under the control of the controller; calculating the time difference H1 between the conduction of the demagnetization module and the disconnection of the first main on-off control module, wherein H1 is | T1-T3| ≦ H; when next demagnetization operation is to be carried out under the condition that the first main on-off control module is switched on, if T1-T3 is more than or equal to 0, the controller sends a demagnetization switching-on instruction to the demagnetization module within H1 time after the controller sends a first switching-off instruction to the first main on-off control module; and if T1-T3 is less than 0, the controller needs to send a de-excitation conducting command to the de-excitation module within H1 time before the controller sends a first off command to the first main on-off control module.
Preferably, when the disconnection reaction time length T1 of the first main on-off control module is detected, under the control of the controller, the first left switch and the first right switch are both disconnected, and then the disconnection reaction time length of the first relay is detected, wherein the disconnection reaction time length of the first relay is T1; after the disconnection reaction time length T1 of the relay I is detected, closing both the left switch and the right switch, and enabling the relay I to be in a disconnection state;
when the disconnection reaction time length T2 of the second main on-off control module is detected, under the control of the controller, the second left switch and the second right switch are disconnected, and then the disconnection reaction time length of the second relay is detected, wherein the disconnection reaction time length of the second relay is T2; after the disconnection reaction time length T2 of the second relay is detected, closing both the second left switch and the second right switch, and enabling the second relay to be in a disconnection state;
when detecting the on-reaction time length T3 of the de-excitation module, under the control of the controller, firstly disconnecting the de-excitation left switch and the de-excitation right switch, and then detecting the closing reaction time length of the de-excitation relay, wherein the closing reaction time length of the de-excitation relay is T3; and after the closing reaction time length T3 of the de-excitation relay is detected, closing the de-excitation left switch and the de-excitation right switch, and enabling the de-excitation relay to be in an off state.
Preferably, if the first main on-off control module and the second main on-off control module are both in the on state, the field suppression process is that if T1 is less than T2, the first main on-off control module is turned off before the second main on-off control module is turned off when field suppression is performed; on the contrary, if T1 is larger than T2, the second main on-off control module is disconnected before the first main on-off control module is disconnected when the magnetic field is removed.
Preferably, the differential protection verification of the high-voltage cable differential protection verification system body is implemented by the following specific steps:
firstly, selecting a 6kV low-voltage transformer to carry out an impact test, and recording impact current; then analyzing the test result, and verifying through other test methods; then, carrying out an impact closing test on the power cable under a rated voltage; then selecting a measuring and recording point at a differential protection screen of a relay room of the 220kV switching station; then, carrying out an impact closing test on the B starting backup transformer under a rated voltage, and measuring and recording an impact waveform; and finally, carrying out comparative analysis on the impact waveform to obtain a final test result, and ending the test.
A solution strategy of a differential protection calibration system of a large-length submarine cable in a no-load state is carried out according to the following steps:
1) before differential protection is put into operation, the outgoing polarity of the rheology needs to be checked with load; a 400V power supply is added from the high-voltage side of the transformer when the low-voltage side of the transformer is in a three-phase short circuit, the current phase of the cable differential CT is obtained by utilizing the self impedance of the transformer, and the CT polarity is verified;
2) performing a through-flow test on the CTs at the two sides of the cable differential protection to check the polarity of the CT;
3) measuring and recording the impact excitation surge current of the transformer to verify the polarity of the cable differential protection CT; when the standby transformer is impacted in production, the secondary currents on two sides required by the differential protection of the cable are led to a point for measuring, recording and comparing.
According to the invention, when the high-voltage cable differential protection calibration system body has a power failure, the de-excitation module immediately starts to de-excite the generator, so that the generator is protected from being burnt out easily. The scheme can also realize the high-voltage cable differential protection verification under the condition of no load, and can automatically perform de-excitation operation on the generator when the high-voltage cable differential protection verification system body has power failure, thereby protecting the generator from the condition that the generator is burnt out due to the power failure of the high-voltage cable differential protection verification system body and prolonging the service life of the generator. Simple structure, good safety and high reliability.
Drawings
FIG. 1 is a schematic diagram of a schematic circuit connection structure according to the present invention;
FIG. 2 is a schematic block diagram of a circuit schematic connection structure of the present invention;
fig. 3 is a schematic diagram of a circuit principle connection structure of the starting-up converter circuit of the present invention.
Detailed Description
The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings.
Example 1: a differential protection verification system for a large-length submarine cable in a no-load state is disclosed, and reference is made to figures 1-3. The device comprises a controller w4, a voice prompter w20, a communication module w21, a field-suppression switch device w19, a high-voltage cable differential protection verification system body w18 and a generator w17 for providing power supply power for the high-voltage cable differential protection verification system body;
the high-voltage cable differential protection checking system body comprises a startup and standby transformer circuit, wherein the startup and standby transformer circuit comprises a 220KV bus, a 220KV power cable differential protection CT1, a 220KV power cable differential protection CT2, an A startup transformer, a 220KV power cable differential protection CT3 and a B startup transformer; one end of a 220KV power cable differential protection CT1 is connected to a 220KV bus, the other end of a 220KV power cable differential protection CT1 is connected to one end of a 220KV power cable, and one end of a 220KV power cable differential protection CT2 and one end of a 220KV power cable differential protection CT3 are connected to the other end of the 220KV power cable; the other end of the 220KV power cable differential protection CT2 is connected to the A backup transformer; the other end of the 220KV power cable differential protection CT3 is connected to a B starting-standby transformer;
the de-excitation switch device comprises a first main on-off control module w1, a second main on-off control module w2 and a de-excitation module w 3; the input end of the first main on-off control module, the input end of the second main on-off control module and the input end of the de-excitation module are respectively connected to the power output end of the generator; the output end of the first main on-off control module and the output end of the second main on-off control module are respectively connected to a 220KV bus; the voice prompter, the communication module, the control end of the high-voltage cable differential protection checking system body, the control end of the first main on-off control module, the control end of the second main on-off control module and the control end of the de-excitation module are respectively connected with the controller.
The magnetic-field-suppression switch further comprises a first node w5 and a second node w6, the first main on-off control module comprises a first left switch w7, a first relay w8 and a first right switch w9, the second main on-off control module comprises a second left switch w10, a second relay w11 and a second right switch w12, and the magnetic-field-suppression module comprises a magnetic-field-suppression left switch w13, a magnetic-field-suppression relay w14, a magnetic-field-suppression right switch w15 and a magnetic-field-suppression resistor w 16;
the left end of the first left switch, the left end of the second left switch and the left end of the de-excitation left switch are respectively connected to the first node; the right end of the first left switch is connected to the left end of the first relay, the right end of the first relay is connected to the left end of the first right switch, and the right end of the first right switch is connected to the second node; the right end of the second left switch is connected to the left end of the second relay, the right end of the second relay is connected to the left end of the second right switch, and the right end of the second right switch is connected to the second node; the right end of the de-excitation left switch is connected to the left end of the de-excitation relay, the right end of the de-excitation relay is connected to the left end of the de-excitation right switch, and the right end of the de-excitation right switch is connected to the de-excitation resistor; the 220KV bus is connected to the second node; the power output end of the generator is connected to the first node;
the control end of the first left switch, the control end of the first relay, the control end of the first right switch, the control end of the second left switch, the control end of the second relay, the control end of the second right switch, the control end of the de-excitation left switch, the control end of the de-excitation relay and the control end of the de-excitation right switch are respectively connected with the controller.
The demagnetization control of the high-voltage cable differential protection verification system in the no-load state is as follows:
the disconnection reaction time length required from the first main on-off control module sending a first disconnection command from the controller to the first main on-off control module completing the disconnection action is T1,
the disconnection reaction time length required from the second main on-off control module sending a second disconnection command from the controller to the second main on-off control module completing the disconnection action is T2,
setting the conduction reaction time length required from the moment that the demagnetization module sends a demagnetization conduction instruction from the controller to the moment that the demagnetization module completes the conduction action as T3;
setting the time required by the de-excitation switching of a generator system corresponding to the high-voltage cable differential protection verification system in the no-load state as H;
when the first main on-off control module is switched on, the second main on-off control module is in an off state, and the value of the off reaction time length T2 of the second main on-off control module and the value of the on reaction time length T3 of the de-excitation module are detected under the control of the controller; calculating the time difference H2 between the conduction of the de-excitation module and the disconnection of the second main on-off control module, wherein H2 is | T2-T3| ≦ H; when next demagnetization operation is to be carried out under the condition that the second main on-off control module is switched on, if T2-T3 is more than or equal to 0, the controller sends a demagnetization switching-on instruction to the demagnetization module within H2 time after the controller sends a second switching-off instruction to the second main on-off control module; if T2-T3 is less than 0, the controller needs to send a de-excitation conducting instruction to the de-excitation module within H2 time before the controller sends a second turn-off instruction to the second main on-off control module;
when the second main on-off control module is switched on, the first main on-off control module is in an off state, and the value of the off reaction time length T1 of the first main on-off control module and the value of the on reaction time length T3 of the de-excitation module are detected under the control of the controller; calculating the time difference H1 between the conduction of the demagnetization module and the disconnection of the first main on-off control module, wherein H1 is | T1-T3| ≦ H; when next demagnetization operation is to be carried out under the condition that the first main on-off control module is switched on, if T1-T3 is more than or equal to 0, the controller sends a demagnetization switching-on instruction to the demagnetization module within H1 time after the controller sends a first switching-off instruction to the first main on-off control module; and if T1-T3 is less than 0, the controller needs to send a de-excitation conducting command to the de-excitation module within H1 time before the controller sends a first turn-off command to the first main on-off control module.
When the disconnection reaction time length T1 of the first main on-off control module is detected, under the control of the controller, the first left switch and the first right switch are disconnected, and then the disconnection reaction time length of the first relay is detected, wherein the disconnection reaction time length of the first relay is T1; after the disconnection reaction time length T1 of the relay I is detected, closing both the left switch and the right switch, and enabling the relay I to be in a disconnection state;
when the disconnection reaction time length T2 of the second main on-off control module is detected, under the control of the controller, the second left switch and the second right switch are disconnected, and then the disconnection reaction time length of the second relay is detected, wherein the disconnection reaction time length of the second relay is T2; after the disconnection reaction time length T2 of the second relay is detected, closing both the second left switch and the second right switch, and enabling the second relay to be in a disconnection state;
when detecting the on-reaction time length T3 of the de-excitation module, under the control of the controller, firstly disconnecting the de-excitation left switch and the de-excitation right switch, and then detecting the closing reaction time length of the de-excitation relay, wherein the closing reaction time length of the de-excitation relay is T3; and after the closing reaction time length T3 of the de-excitation relay is detected, closing the de-excitation left switch and the de-excitation right switch, and enabling the de-excitation relay to be in an off state.
If the first main on-off control module and the second main on-off control module are both in the on state, the magnetic extinguishing process is that if T1 is less than T2, the first main on-off control module is switched off before the second main on-off control module is switched off when the magnetic extinguishing process is carried out; on the contrary, if T1 is larger than T2, the second main on-off control module is disconnected before the first main on-off control module is disconnected when the magnetic field is removed.
The solution strategy of the differential protection calibration system of the large-length submarine cable in the no-load state is as follows:
1) before differential protection is put into operation, the outgoing polarity of the rheology needs to be checked with load; a 400V power supply is added from the high-voltage side of the transformer when the low-voltage side of the transformer is in a three-phase short circuit, the current phase of the cable differential CT is obtained by utilizing the self impedance of the transformer, and the CT polarity is verified;
2) performing a through-flow test on the CTs at two sides of the cable differential protection to check the polarity of the CT;
3) measuring and recording the impact excitation surge current of the transformer to verify the polarity of the cable differential protection CT; when the standby transformer is impacted in production, the secondary currents on two sides required by the differential protection of the cable are led to a point for measuring, recording and comparing.
The polarities of the A phase, the B phase and the C phase of the 220kV cable differential protection are opposite to that of the CT. The CT includes CT1, CT2, and CT 3.
The differential protection verification of the high-voltage cable differential protection verification system body is realized by the following specific steps:
firstly, selecting a 6kV low-voltage transformer to carry out an impact test, and recording impact current; then analyzing the test result, and verifying through other test methods; then, carrying out an impact closing test on the power cable under a rated voltage; then selecting a measuring and recording point at a differential protection screen of a relay room of the 220kV switching station; then, carrying out an impact closing test on the B starting backup transformer under a rated voltage, and measuring and recording an impact waveform; and finally, carrying out comparative analysis on the impact waveform to obtain a final test result, and ending the test.
This embodiment can carry out switch on-off time to it when No. two main on-off control module idleness or main on-off control module idleness respectively and detect, and the reliability is high. When the high-voltage cable differential protection verification system body has a power failure, the de-excitation module immediately starts to de-excite the generator, so that the generator is protected from being burnt out easily. This embodiment when power failure appears in the differential protection check-up system body of high tension cable, can carry out the demagnetization operation to the generator automatically, the protection generator can not lead to the condition that the generator is burnt out to appear because of power failure appears in the differential protection check-up system body of high tension cable to the life of extension generator. Simple structure, good safety and high reliability.
The embodiments of the present invention have been described above with reference to the accompanying drawings, but the implementation is not limited to the above-described embodiments, and those skilled in the art can make various changes or modifications within the scope of the appended claims.
Claims (7)
1. The utility model provides a differential protection check-up system of big length submarine cable unloaded state which characterized in that: the high-voltage cable differential protection verification system comprises a controller, a voice prompter, a communication module, a field suppression switch device, a high-voltage cable differential protection verification system body and a generator for providing power supply power for the high-voltage cable differential protection verification system body;
the high-voltage cable differential protection verification system body comprises a startup and standby transformer circuit, wherein the startup and standby transformer circuit comprises a 220KV bus, a 220KV power cable differential protection CT1, a 220KV power cable differential protection CT2, a startup transformer, a 220KV power cable differential protection CT3 and a B startup transformer; one end of a 220KV power cable differential protection CT1 is connected to a 220KV bus, the other end of a 220KV power cable differential protection CT1 is connected to one end of a 220KV power cable, and one end of a 220KV power cable differential protection CT2 and one end of a 220KV power cable differential protection CT3 are connected to the other end of the 220KV power cable; the other end of the 220KV power cable differential protection CT2 is connected to the A backup transformer; the other end of the 220KV power cable differential protection CT3 is connected to a B starting-standby transformer;
the de-excitation switch device comprises a first main on-off control module, a second main on-off control module and a de-excitation module; the input end of the first main on-off control module, the input end of the second main on-off control module and the input end of the de-excitation module are respectively connected to the power output end of the generator; the output end of the first main on-off control module and the output end of the second main on-off control module are respectively connected to a 220KV bus; the voice prompter, the communication module, the control end of the high-voltage cable differential protection checking system body, the control end of the first main on-off control module, the control end of the second main on-off control module and the control end of the de-excitation module are respectively connected with the controller.
2. The differential protection verification system for the unloaded state of a long submarine cable according to claim 1, wherein: the magnetic field suppression device comprises a first main on-off control module, a second main on-off control module, a first switch, a first relay and a first right switch, wherein the second main on-off control module comprises a second left switch, a second relay and a second right switch;
the left end of the first left switch, the left end of the second left switch and the left end of the de-excitation left switch are respectively connected to the first node; the right end of the first left switch is connected to the left end of the first relay, the right end of the first relay is connected to the left end of the first right switch, and the right end of the first right switch is connected to the second node; the right end of the second left switch is connected to the left end of the second relay, the right end of the second relay is connected to the left end of the second right switch, and the right end of the second right switch is connected to the second node; the right end of the de-excitation left switch is connected to the left end of the de-excitation relay, the right end of the de-excitation relay is connected to the left end of the de-excitation right switch, and the right end of the de-excitation right switch is connected to the de-excitation resistor; the 220KV bus is connected to the second node; the power output end of the generator is connected to the first node;
the control end of the first left switch, the control end of the first relay, the control end of the first right switch, the control end of the second left switch, the control end of the second relay, the control end of the second right switch, the control end of the de-excitation left switch, the control end of the de-excitation relay and the control end of the de-excitation right switch are respectively connected with the controller.
3. The differential protection verification system for the unloaded state of a long submarine cable according to claim 2, wherein: the de-excitation control of the de-excitation switch device is as follows:
setting the disconnection reaction time length required by the first main on-off control module from the time when the first main on-off control module sends a first disconnection command to the time when the first main on-off control module completes the disconnection action as T1, setting the disconnection reaction time length required by the second main on-off control module from the time when the second main on-off control module sends a second disconnection command to the time when the second main on-off control module completes the disconnection action as T2, and setting the conduction reaction time length required by the demagnetization module from the time when the demagnetization module sends a demagnetization conduction command to the time when the demagnetization module completes the conduction action as T3; setting the time required by the de-excitation switching of the generator system corresponding to the de-excitation switch device as H;
when the first main on-off control module is switched on, the second main on-off control module is in an off state, and the value of the off reaction time length T2 of the second main on-off control module and the value of the on reaction time length T3 of the de-excitation module are detected under the control of the controller; calculating the time difference H2 between the conduction of the de-excitation module and the disconnection of the second main on-off control module, wherein H2 is | T2-T3| ≦ H; when next demagnetization operation is to be carried out under the condition that the second main on-off control module is switched on, if T2-T3 is more than or equal to 0, the controller sends a demagnetization switching-on instruction to the demagnetization module within H2 time after the controller sends a second switching-off instruction to the second main on-off control module; if T2-T3 is less than 0, the controller needs to send a de-excitation conducting instruction to the de-excitation module within H2 time before the controller sends a second turn-off instruction to the second main turn-on and turn-off control module;
when the second main on-off control module is switched on, the first main on-off control module is in an off state, and the value of the off reaction time length T1 of the first main on-off control module and the value of the on reaction time length T3 of the de-excitation module are detected under the control of the controller; calculating the time difference H1 between the conduction of the demagnetization module and the disconnection of the first main on-off control module, wherein H1 is | T1-T3| ≦ H; when next demagnetization operation is to be carried out under the condition that the first main on-off control module is switched on, if T1-T3 is more than or equal to 0, the controller sends a demagnetization switching-on instruction to the demagnetization module within H1 time after the controller sends a first switching-off instruction to the first main on-off control module; and if T1-T3 is less than 0, the controller needs to send a de-excitation conducting command to the de-excitation module within H1 time before the controller sends a first off command to the first main on-off control module.
4. The differential protection verification system for the unloaded state of a long submarine cable according to claim 3, wherein: when the disconnection reaction time length T1 of the first main on-off control module is detected, under the control of the controller, the first left switch and the first right switch are disconnected, and then the disconnection reaction time length of the first relay is detected, wherein the disconnection reaction time length of the first relay is T1; after the disconnection reaction time length T1 of the relay I is detected, closing both the left switch and the right switch, and enabling the relay I to be in a disconnection state;
when the disconnection reaction time length T2 of the second main on-off control module is detected, under the control of the controller, the second left switch and the second right switch are disconnected, and then the disconnection reaction time length of the second relay is detected, wherein the disconnection reaction time length of the second relay is T2; after the disconnection reaction time length T2 of the second relay is detected, closing both the second left switch and the second right switch, and enabling the second relay to be in a disconnection state;
when detecting the on-reaction time length T3 of the de-excitation module, under the control of the controller, firstly disconnecting the de-excitation left switch and the de-excitation right switch, and then detecting the closing reaction time length of the de-excitation relay, wherein the closing reaction time length of the de-excitation relay is T3; and after the closing reaction time length T3 of the de-excitation relay is detected, closing the de-excitation left switch and the de-excitation right switch, and enabling the de-excitation relay to be in an off state.
5. The differential protection verification system for the no-load condition of the long submarine cable according to claim 3, wherein the de-excitation process when the first main on-off control module and the second main on-off control module are both in the on-state is that when the de-excitation is performed when T1 is less than T2, the first main on-off control module is disconnected before the second main on-off control module is disconnected; on the contrary, if T1 is larger than T2, the second main on-off control module is disconnected before the first main on-off control module is disconnected when the magnetic field is removed.
6. The differential protection verification system of the large-length submarine cable in the no-load state according to claim 1, wherein the differential protection verification of the high-voltage cable differential protection verification system body is implemented by the following specific steps:
firstly, selecting a 6kV low-voltage transformer to carry out an impact test, and recording impact current; then analyzing the test result, and verifying through other test methods; then, carrying out an impact closing test on the power cable under a rated voltage; then selecting a measuring and recording point at a differential protection screen of a relay room of the 220kV switching station; then, carrying out an impact closing test on the B starting backup transformer under a rated voltage, and measuring and recording an impact waveform; and finally, carrying out comparative analysis on the impact waveform to obtain a final test result, and ending the test.
7. The solution strategy of the differential protection verification system of the large-length submarine cable in the no-load state according to claim 1, is characterized by comprising the following steps:
1) before differential protection is put into operation, the outgoing polarity of the rheology needs to be checked with load; a 400V power supply is added from the high-voltage side of the transformer when the low-voltage side of the transformer is in a three-phase short circuit, the current phase of the cable differential CT is obtained by utilizing the self impedance of the transformer, and the CT polarity is verified;
2) performing a through-flow test on the CTs at the two sides of the cable differential protection to check the polarity of the CT;
3) measuring and recording the impact excitation surge current of the transformer to verify the polarity of the cable differential protection CT; when the standby transformer is impacted in production, the secondary currents on two sides required by the differential protection of the cable are led to a point for measuring, recording and comparing.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI797786B (en) * | 2021-10-20 | 2023-04-01 | 財團法人金屬工業研究發展中心 | Submarine cable, device and method for monitoring fault of submarine cable |
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| JP2006020452A (en) * | 2004-07-02 | 2006-01-19 | Hitachi Ltd | Protection relay system for generator main circuit |
| CN108181528A (en) * | 2017-12-31 | 2018-06-19 | 中国能源建设集团华东电力试验研究院有限公司 | The high-tension cable differential protection check system of no load condition |
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