CN111366878A - System and method for verifying differential protection polarity of startup and standby variable branch - Google Patents
System and method for verifying differential protection polarity of startup and standby variable branch Download PDFInfo
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- CN111366878A CN111366878A CN202010324959.6A CN202010324959A CN111366878A CN 111366878 A CN111366878 A CN 111366878A CN 202010324959 A CN202010324959 A CN 202010324959A CN 111366878 A CN111366878 A CN 111366878A
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Abstract
The invention discloses a system and a method for verifying the differential protection polarity of a startup and standby variable branch. The generator is used as a current source, short-circuit tests are respectively carried out on the high-voltage side and the low-voltage side of the starting-up and standby transformer, the polarity of a newly-accessed starting-up and standby transformer branch and the polarity of the starting-up and standby transformer differential protection are verified by using the short-circuit current, defects are eliminated, and the normal operation of the differential protection is ensured. The method solves the problem that the starting-up variable load current cannot verify the bus differential protection, does not need to organize a large number of loads, does not need to rent dummy loads, and has strong operability. The polarity of the bus differential protection and the polarity of the startup and standby differential protection can be ensured to be correct, and the differential protection misoperation can be prevented.
Description
Technical Field
The invention relates to the technical field of power tests, in particular to a system and a method for verifying the differential protection polarity of a starting-standby variable branch.
Background
The differential protection is the main protection of the power system, and the operation quality of the differential protection is related to whether the fault can be correctly cut off under the accident condition. The differential protection system is occasionally subjected to protection misoperation events caused by inaccurate wiring and inaccurate checking, multipoint grounding of a secondary circuit and the like. Therefore, polarity check should be performed before differential protection is put into operation, on one hand, defects such as wiring errors are eliminated; on the other hand, the differential protection is checked whether the differential protection is in malfunction when the load current flows normally. Differential protection polarity verification is typically accomplished through a load test.
The power plant extension project generally needs to set a starting-up transformer as a starting and standby power supply, the starting-up transformer is generally connected to a 220kV or 500kV bus, and therefore differential protection needs to be verified after bus differential protection is connected to a branch of the starting-up transformer and before the starting-up transformer differential protection is put into operation. For the startup variable branch differential guard band load check, there are two difficulties as follows: the load equipment of the power plant mainly comprises a fan and a water pump, large loads are difficult to organize in the initial construction stage, dummy loads are required to be rented as the loads, and the cost is high; secondly, the starting-up variable capacitance is limited, usually 30MVA or 50MVA, the load current of the high-voltage side is very small when the starting-up variable capacitance is in normal operation and is lower than the unbalanced current of the bus differential protection, and the pure load current cannot complete the verification of the bus differential protection.
Therefore, a system and a method for starting up the differential protection polarity check of the branch of the backup transformer, which are convenient to operate, accurate and reliable, are needed to be found.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a system and a method for verifying the differential protection polarity of a starting-up variable branch. The method does not need to organize a large amount of loads and rent dummy loads, and is reliable and high in operability.
In order to achieve the purpose, the invention adopts the technical scheme that:
a system for verifying the differential protection polarity of a startup and standby variable branch comprises a high-voltage bus 3, wherein the high-voltage bus 3 is connected with a generator transformer unit 2 and a startup and standby variable unit 4, the generator transformer unit 2 is connected with a generator excitation unit 1, the startup and standby variable unit 4 is connected with a startup and standby variable branch unit 5 and a startup and standby variable branch unit 6, and the startup and standby variable unit 4, the startup and standby variable branch unit 5 and the startup and standby variable branch unit 6 are connected with a startup and standby variable differential protection unit 8.
The generator excitation unit 1 comprises an excitation transformer 9, and the excitation transformer 9 is connected with a field suppression switch 11 through an excitation regulator 10.
The generator transformer unit 2 comprises a generator 12, the generator 12 is connected with a main transformer 14 through a generator outlet closed bus 13, the main transformer 14 is connected with a main transformer high-voltage side circuit breaker 16 through a main transformer high-voltage side current transformer 15, and the main transformer high-voltage side circuit breaker 16 is connected with a high-voltage bus 3.
The starting and standby transformer unit 4 comprises a starting and standby high-voltage side circuit breaker 17 connected with the high-voltage bus 3, and the starting and standby high-voltage side circuit breaker 17 is sequentially connected with a starting and standby high-voltage side current transformer I18, a starting and standby high-voltage side current transformer II 19 and a starting and standby high-voltage side grounding disconnecting link 27;
the starting-standby transformer branch unit 5 comprises a starting-standby transformer branch short-circuit device 22, and the starting-standby transformer branch short-circuit device 22 is connected with a starting-standby transformer branch current transformer 21 and a starting-standby transformer branch bus 23 at a time; the starting-standby transformer branch unit 6 comprises a starting-standby transformer branch short-circuit device 25, and the starting-standby transformer branch short-circuit device 25 is sequentially connected with a starting-standby transformer branch current transformer 24 and a starting-standby transformer branch bus 26.
The secondary current of the main transformer high-voltage side current transformer 15 and the secondary current of the standby high-voltage side current transformer I18 are transmitted to the bus differential protection 7 to form bus differential protection;
and the secondary current of the second starting-up and standby high-voltage side current transformer 19, the secondary current of the first starting-up and standby transformer branch current transformer 21 and the secondary current of the first starting-up and standby transformer branch current transformer 24 are transmitted to the starting-up and standby transformer differential protection 8 to form the starting-up and standby transformer differential protection.
A check method for checking the differential protection polarity of a starting and standby variable branch comprises the following steps;
1) carrying out preparation work of the polarity check of the starting and standby variable branches of the bus differential protection 7;
2) adjusting the output of the generator 12 to ensure that the secondary current of the starting-standby transformer high-voltage side of the first starting-standby transformer high-voltage side current transformer 18 is 1A;
3) measuring and recording main transformer high-voltage side current of a main transformer high-voltage side current transformer 15 and standby high-voltage side current of a standby high-voltage side current transformer I18;
4) checking whether the differential flow of the bus differential protection 7 is zero, if the differential flow of the bus differential protection 7 is zero, turning to the step 6), and if the differential flow of the bus differential protection 7 is not zero, turning to the step 5);
5) reducing the standby high-voltage side current to zero, and checking and eliminating CT defects;
6) carrying out check preparation of a starting-up and standby differential protection 8;
7) regulating the output of the generator 12 to ensure that the secondary current of the starting and standby high-voltage side of the second starting and standby high-voltage side current transformer 19 is rated current;
8) measuring and recording a starting-up transformer high-voltage side current of a starting-up transformer high-voltage side current transformer II 19, a starting-up transformer one-branch current of a starting-up transformer one-branch current transformer 21 and a starting-up transformer two-branch current of a starting-up transformer two-branch current transformer 24;
9) checking whether the differential stream of the starting-up variable differential protection 8 is zero, if the differential stream of the starting-up variable differential protection 8 is zero, turning to the step 11), and when the differential stream of the starting-up variable differential protection 8 is not zero, turning to the step 10);
11) and (5) starting the variable branch differential protection polarity verification test and ending the test.
The specific operation process of the step 1) is as follows:
101) checking and confirming that a secondary circuit of a main transformer high-voltage side current transformer 15 and a secondary circuit of a standby high-voltage side current transformer I18 are accurately connected, the transformation ratio selection and the fixed value of the current transformers are consistent, and the secondary circuit has no open circuit phenomenon;
102) checking and confirming that the main transformer high-voltage side circuit breaker 16 and the starting and standby transformer high-voltage side circuit breaker 17 are in a closing state and the control power supply is withdrawn;
103) checking and confirming that a starting high-voltage side grounding knife switch 27 serving as a short-circuit device is in a closing state, the grounding knife switch is in good contact, and A, B, C three phases pass through a grounding grid to form the short-circuit device;
104) and checking to confirm that the excitation transformer is electrified, closing a de-excitation switch 11, adjusting the working mode of the excitation regulator 10 to be a manual state, and starting the standby variable branch to have a through-flow condition.
The step 4) comprises the following steps:
401) checking whether main transformer high-voltage side current of a main transformer high-voltage side current transformer 15, standby high-voltage side current of a standby high-voltage side current transformer I18 and a calculated value are consistent;
402) reading main transformer high-voltage side current of a main transformer high-voltage side current transformer 15 and standby high-voltage side current of a standby high-voltage side current transformer I18 at a bus differential protection 7, and checking whether the current is consistent with a measured value;
403) checking whether the differential current of the bus differential protection 7 is zero, and if the differential current is zero, determining that the polarity of the standby branch current of the standby high-voltage side current transformer I18 of the newly-accessed bus differential protection 7 is correct; if the current is not zero, the polarity of the secondary current accessed by the starting transformer unit 4 is considered to be incorrect.
The step 5) comprises the following steps:
501) the standby high-voltage side current of the standby high-voltage side current transformer I18 is reduced to zero, the motor field suppression switch 11 is distributed, the field suppression switch 11 is withdrawn from a control power supply, and the power supply of the excitation transformer 9 is disconnected;
502) checking whether the current on the startup high-voltage side of a startup transformer high-voltage side current transformer I18 accessed by the startup transformer unit 4 of the bus differential protection 7 is enough to have a shunting phenomenon, checking whether the transformation ratio of the selected current transformer is consistent with a design value, checking whether the polarity of the accessed current is correct, and eliminating defects after confirmation.
The step 6) comprises the following steps:
601) the standby high-voltage side current of the standby high-voltage side current transformer I18 is reduced to zero, the motor field suppression switch 11 is distributed, the field suppression switch 11 is withdrawn from a control power supply, and the power supply of the excitation transformer 9 is disconnected;
602) separately starting the standby high-voltage side grounding disconnecting link 27 and quitting the control and power supply thereof;
603) checking that a starting-standby branch current loop of the starting-standby branch current transformer 21 and a starting-standby branch current loop of the starting-standby branch current transformer 24 are accurately connected, the transformation ratio selection of the current transformers is consistent with the fixed value, and a secondary loop has no open circuit phenomenon;
604) checking to confirm that the starting-standby branch short-circuit device 22 is installed and in good contact, and short-circuiting the three phases of the starting-standby branch A, B, C through the short-circuit device; checking and confirming that the starting-up and standby transformer two-branch short-circuit device 25 is installed and well contacted, and the three phases of the starting-up and standby transformer two-branch A, B, C are short-circuited through the short-circuit device;
605) the excitation transformer 9 is powered on, the field-extinguishing switch 11 is closed, the working mode of the excitation regulator 10 is adjusted to be in a manual state, and the low-voltage side branch is started and provided with a through-current condition.
The step 9) comprises the following steps:
901) checking whether main transformer high-voltage side current of a starting-standby transformer high-voltage side current transformer II 19, starting-standby transformer branch current of a starting-standby transformer branch current transformer 21 and branch current of a starting-standby transformer branch current transformer 24 are consistent with the calculated value;
902) reading a starting-up transformer high-voltage side current of a starting-up transformer high-voltage side current transformer II 19, a starting-up transformer branch current transformer 21 and a starting-up transformer branch current of a starting-up transformer branch current transformer 24 in the starting-up transformer differential protection, and checking whether the starting-up transformer high-voltage side current and the starting-up transformer branch current are consistent with a measured value;
903) checking whether the differential current of the starting-standby transformer differential protection 8 is zero, and if the differential current is zero, considering that the polarities of the starting-standby transformer branch current of the connected starting-standby transformer branch current transformer 21 and the two branch currents of the starting-standby transformer branch current transformer 24 are correct; if the polarity is not zero, the polarity of the secondary current switched in by the starting-up and converting branch unit 5 and the starting-up and converting branch unit 6 is not correct.
The step 10) comprises the following steps:
1001) the standby high-voltage side current of the standby high-voltage side current transformer II 19 is reduced to zero, the motor field suppression switch 11 is distributed, the field suppression switch 11 is withdrawn from a control power supply, and the power supply of the excitation transformer 9 is disconnected;
1002) and checking whether the current on the low-voltage side of the startup transformer accessed by the startup transformer differential protection 8, the startup transformer branching unit 5 and the startup transformer branching unit 6 is enough to have a shunting phenomenon, checking whether the transformation ratio of the selected current transformer is consistent with a design value, checking whether the polarity of the accessed current is correct, and eliminating defects after confirmation.
The invention has the beneficial effects that:
when the system and the method for verifying the differential protection polarity of the starting-standby variable branch are operated specifically, the generator is used as a current source, the short-circuit current is used for verifying the polarity of the newly-accessed starting-standby variable branch and the differential protection polarity of the starting-standby variable branch by using the differential protection of the bus, the defects are eliminated, and the normal operation of the differential protection is ensured. The method solves the problem that the startup variable load current cannot verify the bus differential protection, does not need to organize a large number of loads, does not need to rent dummy loads, and has good economy and strong operability. The method is suitable for high-voltage buses with different main wiring modes, is suitable for starting and standby transformers with different wiring modes, is convenient to popularize and use on site, ensures the accuracy and reliability of bus differential protection and starting and standby transformer differential protection, and prevents misoperation of differential protection.
Drawings
FIG. 1 is a circuit diagram of the present invention;
FIG. 2 is a flow chart of the present invention.
Wherein, 1 is a generator excitation unit, 2 is a generator transformer unit, 3 is a high-voltage bus, 4 is a startup transformer unit, 5 is a startup-standby transformer one-branch unit, 6 is a startup-standby transformer two-branch unit, 7 is a bus differential protection device, 8 is a startup-standby transformer differential protection, 9 is an excitation transformer, 10 is a rectifier cabinet and an excitation regulator, 11 is a de-excitation switch, 12 is a generator, 13 is a generator closed bus, 14 is a main transformer, 15 is a main transformer high-voltage side current transformer, 16 is a main transformer high-voltage side circuit breaker, 17 is a startup-standby high-voltage side circuit breaker, 18, a startup-standby high-voltage side current transformer one, 19, a startup-standby high-voltage side current transformer two, 20 is a startup transformer, 21 is a startup-standby transformer one-branch current transformer, 22 is a startup-standby transformer one-branch short-circuit device, 23 is a startup-standby transformer one-branch bus, 24 is a startup-standby transformer two-branch current, The device 25 is a starting-up and standby variable-two-branch short-circuit device, the 26 is a starting-up and standby variable-two-branch bus, and the 27 is a starting-up and standby variable-high voltage side grounding disconnecting link.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
Referring to fig. 1, the system for verifying the startup and standby variable branch differential protection polarity of the invention includes a generator excitation unit 1, a generator transformer unit 2, a high-voltage bus 3, a startup and standby variable unit 4, a startup and standby variable one-branch unit 5, a startup and standby variable two-branch unit 6, a bus differential protection device 7, and a startup and standby variable differential protection device 8. The generator transformer unit 2 and the starting and standby transformer unit 4 are connected with a high-voltage bus 3; the generator exciting unit 1 provides exciting current for the generator; and the standby transformer branch unit 5 and the standby transformer branch unit 6T are connected on the low-voltage side of the standby transformer.
The generator exciting unit 1 includes: an excitation transformer 9, a rectifying device, an excitation regulator 10 and a field suppression switch 11; the generator transformer unit 2 includes: the generator comprises a generator 12, a generator outlet closed bus 13, a main transformer 14, a main transformer high-voltage side current transformer 15 and a main transformer high-voltage side circuit breaker 16; the standby transformer unit 4 includes: a standby high-voltage side circuit breaker 17, a standby high-voltage side current transformer I18, a standby high-voltage side current transformer II 19 and a standby high-voltage side grounding disconnecting link 27 are started; the standby change branching unit 5 includes: the system comprises a starting-up transformer-branch short-circuit device 22, a starting-up transformer-branch current transformer 21 and a starting-up transformer-branch bus 23; the standby change branching unit 6 includes: the system comprises a starting-up and standby transformer bifurcate short-circuit device 25, a starting-up and standby transformer bifurcate current transformer 24 and a starting-up and standby transformer bifurcate bus 26.
Secondary current of a main transformer high-voltage side current transformer 15 and secondary current of a standby high-voltage side current transformer I18 are transmitted to a bus differential protection device 7 to form bus differential protection; and the secondary current of the second startup transformer high-voltage side current transformer 19, the secondary current of the first startup transformer branch current transformer 21 and the secondary current of the second startup transformer branch current transformer 24 are transmitted to the startup transformer differential protection 8 to form the startup transformer differential protection.
With reference to figure 2 of the drawings,
a check method for checking the differential protection polarity of a starting and standby variable branch comprises the following steps;
1) carrying out preparation work of the polarity check of the starting and standby variable branches of the bus differential protection 7;
2) adjusting the output of the generator 12 to ensure that the secondary current of the starting-standby transformer high-voltage side of the first starting-standby transformer high-voltage side current transformer 18 is 1A;
3) measuring and recording main transformer high-voltage side current of a main transformer high-voltage side current transformer 15 and standby high-voltage side current of a standby high-voltage side current transformer I18;
4) checking whether the differential flow of the bus differential protection 7 is zero, if the differential flow of the bus differential protection 7 is zero, turning to the step 6), and if the differential flow of the bus differential protection 7 is not zero, turning to the step 5);
5) reducing the standby high-voltage side current to zero, and checking and eliminating CT defects;
6) carrying out check preparation of a starting-up and standby differential protection 8;
7) regulating the output of the generator 12 to ensure that the secondary current of the starting and standby high-voltage side of the second starting and standby high-voltage side current transformer 19 is rated current;
8) measuring and recording a starting-up transformer high-voltage side current of a starting-up transformer high-voltage side current transformer II 19, a starting-up transformer one-branch current of a starting-up transformer one-branch current transformer 21 and a starting-up transformer two-branch current of a starting-up transformer two-branch current transformer 24;
9) checking whether the differential stream of the starting-up variable differential protection 8 is zero, if the differential stream of the starting-up variable differential protection 8 is zero, turning to the step 11), and when the differential stream of the starting-up variable differential protection 8 is not zero, turning to the step 10);
11) and (5) starting the variable branch differential protection polarity verification test and ending the test.
The specific operation process of the step 1) is as follows:
101) checking and confirming that a secondary circuit of a main transformer high-voltage side current transformer 15 and a secondary circuit of a standby high-voltage side current transformer I18 are accurately connected, the transformation ratio selection and the fixed value of the current transformers are consistent, and the secondary circuit has no open circuit phenomenon;
102) checking and confirming that the main transformer high-voltage side circuit breaker 16 and the starting and standby transformer high-voltage side circuit breaker 17 are in a closing state and the control power supply is withdrawn;
103) checking and confirming that a starting high-voltage side grounding knife switch 27 serving as a short-circuit device is in a closing state, the grounding knife switch is in good contact, and A, B, C three phases pass through a grounding grid to form the short-circuit device;
104) and checking to confirm that the excitation transformer is electrified, closing a de-excitation switch 11, adjusting the working mode of the excitation regulator 10 to be a manual state, and starting the standby variable branch to have a through-flow condition.
The step 4) comprises the following steps:
401) checking whether main transformer high-voltage side current of a main transformer high-voltage side current transformer 15, standby high-voltage side current of a standby high-voltage side current transformer I18 and a calculated value are consistent;
402) reading main transformer high-voltage side current of a main transformer high-voltage side current transformer 15 and standby high-voltage side current of a standby high-voltage side current transformer I18 at a bus differential protection 7, and checking whether the current is consistent with a measured value;
403) checking whether the differential current of the bus differential protection 7 is zero, and if the differential current is zero, determining that the polarity of the standby branch current of the standby high-voltage side current transformer I18 of the newly-accessed bus differential protection 7 is correct; if the current is not zero, the polarity of the secondary current accessed by the starting transformer unit 4 is considered to be incorrect.
The step 5) comprises the following steps:
501) the standby high-voltage side current of the standby high-voltage side current transformer I18 is reduced to zero, the motor field suppression switch 11 is distributed, the field suppression switch 11 is withdrawn from a control power supply, and the power supply of the excitation transformer 9 is disconnected;
502) checking whether the current on the startup high-voltage side of a startup transformer high-voltage side current transformer I18 accessed by the startup transformer unit 4 of the bus differential protection 7 is enough to have a shunting phenomenon, checking whether the transformation ratio of the selected current transformer is consistent with a design value, checking whether the polarity of the accessed current is correct, and eliminating defects after confirmation.
The step 6) comprises the following steps:
601) the standby high-voltage side current of the standby high-voltage side current transformer I18 is reduced to zero, the motor field suppression switch 11 is distributed, the field suppression switch 11 is withdrawn from a control power supply, and the power supply of the excitation transformer 9 is disconnected;
602) separately starting the standby high-voltage side grounding disconnecting link 27 and quitting the control and power supply thereof;
603) checking that a starting-standby branch current loop of the starting-standby branch current transformer 21 and a starting-standby branch current loop of the starting-standby branch current transformer 24 are accurately connected, the transformation ratio selection of the current transformers is consistent with the fixed value, and a secondary loop has no open circuit phenomenon;
604) checking to confirm that the starting-standby branch short-circuit device 22 is installed and in good contact, and short-circuiting the three phases of the starting-standby branch A, B, C through the short-circuit device; checking and confirming that the starting-up and standby transformer two-branch short-circuit device 25 is installed and well contacted, and the three phases of the starting-up and standby transformer two-branch A, B, C are short-circuited through the short-circuit device;
605) the excitation transformer 9 is powered on, the field-extinguishing switch 11 is closed, the working mode of the excitation regulator 10 is adjusted to be in a manual state, and the low-voltage side branch is started and provided with a through-current condition.
The step 9) comprises the following steps:
901) checking whether main transformer high-voltage side current of a starting-standby transformer high-voltage side current transformer II 19, starting-standby transformer branch current of a starting-standby transformer branch current transformer 21 and branch current of a starting-standby transformer branch current transformer 24 are consistent with the calculated value;
902) reading a starting-up transformer high-voltage side current of a starting-up transformer high-voltage side current transformer II 19, a starting-up transformer branch current transformer 21 and a starting-up transformer branch current of a starting-up transformer branch current transformer 24 in the starting-up transformer differential protection, and checking whether the starting-up transformer high-voltage side current and the starting-up transformer branch current are consistent with a measured value;
903) checking whether the differential current of the starting-standby transformer differential protection 8 is zero, and if the differential current is zero, considering that the polarities of the starting-standby transformer branch current of the connected starting-standby transformer branch current transformer 21 and the two branch currents of the starting-standby transformer branch current transformer 24 are correct; if the polarity is not zero, the polarity of the secondary current switched in by the starting-up and converting branch unit 5 and the starting-up and converting branch unit 6 is not correct.
The step 10) comprises the following steps:
1001) the standby high-voltage side current of the standby high-voltage side current transformer II 19 is reduced to zero, the motor field suppression switch 11 is distributed, the field suppression switch 11 is withdrawn from a control power supply, and the power supply of the excitation transformer 9 is disconnected;
1002) and checking whether the current on the low-voltage side of the startup transformer accessed by the startup transformer differential protection 8, the startup transformer branching unit 5 and the startup transformer branching unit 6 is enough to have a shunting phenomenon, checking whether the transformation ratio of the selected current transformer is consistent with a design value, checking whether the polarity of the accessed current is correct, and eliminating defects after confirmation.
The method utilizes a generator as a current source to respectively perform short-circuit tests on a high-voltage side and a low-voltage side of the starting-up and standby transformer, utilizes a short-circuit current to verify the polarity of a newly-accessed starting-up and standby transformer branch and the polarity of the starting-up and standby transformer differential protection, eliminates defects and ensures that the differential protection operates normally. The method solves the problem that the startup variable load current cannot verify the bus differential protection, does not need to organize a large number of loads, does not need to rent dummy loads, and has good economy and strong operability. The method is suitable for high-voltage buses with different main wiring modes, is suitable for starting and standby transformers with different wiring modes, is convenient to popularize and use on site, ensures the accuracy and reliability of bus differential protection and starting and standby transformer differential protection, and prevents misoperation of differential protection.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and all simple modifications, changes and equivalent structural changes made to the above embodiment according to the technical spirit of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims (10)
1. The system for verifying the startup and standby variable branch differential protection polarity is characterized by comprising a high-voltage bus (3), wherein the high-voltage bus (3) is connected with a generator transformer unit (2) and a startup and standby variable unit (4), a generator excitation unit (1) is connected to the generator transformer unit (2), a startup and standby variable branch unit (5) and a startup and standby variable branch unit (6) are connected to the startup and standby variable unit (4), and the startup and standby variable unit (4), the startup and standby variable branch unit (5) and the startup and standby variable branch unit (6) are connected with a startup and standby variable differential protection unit (8).
2. A system for verifying the polarity of a backup variable differential protection according to claim 1, wherein the generator excitation unit (1) comprises an excitation transformer (9), the excitation transformer (9) is connected to the field switch (11) through an excitation regulator (10);
the generator transformer unit (2) comprises a generator (12), the generator (12) is connected with a main transformer (14) through a generator outlet closed bus (13), the main transformer (14) is connected with a main transformer high-voltage side circuit breaker (16) through a main transformer high-voltage side current transformer (15), and the main transformer high-voltage side circuit breaker (16) is connected with a high-voltage bus (3);
the starting and standby transformer unit (4) comprises a starting and standby transformer high-voltage side circuit breaker (17) connected with the high-voltage bus (3), and the starting and standby transformer high-voltage side circuit breaker (17) is sequentially connected with a starting and standby high-voltage side current transformer I (18), a starting and standby high-voltage side current transformer II (19) and a starting and standby high-voltage side grounding disconnecting link (27).
3. The system for verifying the differential protection polarity of the starting-standby transformer branch according to claim 1, wherein the starting-standby transformer branch unit (5) comprises a starting-standby transformer branch short-circuit device (22), and the starting-standby transformer branch short-circuit device (22) is connected with the starting-standby transformer branch current transformer (21) and the starting-standby transformer branch bus (23) at a time; the starting-standby transformer secondary branch unit (6) comprises a starting-standby transformer secondary branch short-circuit device (25), and the starting-standby transformer secondary branch short-circuit device (25) is sequentially connected with a starting-standby transformer secondary branch current transformer (24) and a starting-standby transformer secondary branch bus (26);
the secondary current of the main transformer high-voltage side current transformer (15) and the secondary current of the standby high-voltage side current transformer I18 are transmitted to the bus differential protection device (7) to form bus differential protection;
and the secondary current of the second starting-standby high-voltage side current transformer (19), the secondary current of the first starting-standby transformer branch current transformer (21) and the secondary current of the first starting-standby transformer branch current transformer (24) are transmitted to the differential protection (8) to form the differential protection.
4. A method for verifying a system for verifying the polarity of a backup variable differential protection according to claim 1, comprising the steps of;
1) carrying out preparation work of starting up the polarity check of the branch of the bus differential protection (7);
2) adjusting the output of the generator (12) to ensure that the secondary current of the starting and standby high-voltage side of the first starting and standby high-voltage side current transformer (18) is 1A;
3) measuring and recording main transformer high-voltage side current of a main transformer high-voltage side current transformer (15) and standby high-voltage side current of a standby high-voltage side current transformer I (18);
4) checking whether the differential flow of the bus differential protection (7) is zero, if the differential flow of the bus differential protection (7) is zero, turning to the step 6), and if the differential flow of the bus differential protection (7) is not zero, turning to the step 5);
5) reducing the standby high-voltage side current to zero, and checking and eliminating CT defects;
6) carrying out check preparation of the starting-up and standby variable differential protection (8);
7) the output of the generator (12) is regulated, and the secondary current of the starting-standby transformer high-voltage side current transformer II (19) is ensured to be rated current;
8) measuring and recording a starting-up transformer high-voltage side current of a starting-up transformer high-voltage side current transformer II (19), a starting-up transformer branch current of a starting-up transformer branch current transformer (21) and a starting-up transformer branch current of a starting-up transformer branch current transformer 24;
9) checking whether the differential flow of the starting-up variable differential protection (8) is zero, if the differential flow of the starting-up variable differential protection (8) is zero, turning to the step 11), and if the differential flow of the starting-up variable differential protection (8) is not zero, turning to the step 10);
11) and (5) starting the variable branch differential protection polarity verification test and ending the test.
5. The method for verifying the differential protection polarity of the startup variable branch according to claim 4, wherein the specific operation process of the step 1) is as follows:
101) checking and confirming that a secondary circuit of a main transformer high-voltage side current transformer (15) and a secondary circuit of a standby high-voltage side current transformer I (18) are accurately wired, the ratio selection of the current transformers is consistent with a fixed value, and the secondary circuit has no open circuit phenomenon;
102) checking and confirming that a main transformer high-voltage side circuit breaker (16) and a standby transformer high-voltage side circuit breaker (17) are in a closing state and a control power supply is withdrawn;
103) checking and confirming that a starting high-voltage side grounding knife switch 27 serving as a short-circuit device is in a closing state, the grounding knife switch is in good contact, and A, B, C three phases pass through a grounding grid to form the short-circuit device;
104) and checking to confirm that the excitation transformer is electrified, closing a de-excitation switch (11), adjusting the working mode of the excitation regulator (10) to be a manual state, and starting the variable branch to have a through-flow condition.
6. A verification method for verifying the polarity of the differential protection of the startup variable branch according to claim 4, wherein said step 4) comprises the steps of:
401) checking whether main transformer high-voltage side current of a main transformer high-voltage side current transformer (15) and standby high-voltage side current of a standby high-voltage side current transformer I18 are consistent with the calculated value;
402) reading main transformer high-voltage side current of a main transformer high-voltage side current transformer (15) and standby high-voltage side current of a standby high-voltage side current transformer I (18) in a bus differential protection (7), and checking whether the current is consistent with a measured value;
403) checking whether the differential current of the bus differential protection (7) is zero, and if the differential current is zero, determining that the polarity of the standby branch current of the standby high-voltage side current transformer I (18) of the newly-accessed bus differential protection (7) is correct; if the polarity of the secondary current switched in by the starting transformer unit (4) is not correct, the polarity of the secondary current is not zero.
7. A verification method for verifying the polarity of the differential protection of the startup variable branch according to claim 4, wherein said step 5) comprises the steps of:
501) the standby high-voltage side current of the standby high-voltage side current transformer I (18) is reduced to zero, the motor field-suppression switch (11) is distributed, the field-suppression switch (11) is withdrawn to control the power supply, and the power supply of the excitation transformer (9) is disconnected;
502) the method comprises the steps of checking whether the current on the starting and standby high-voltage side of a first starting and standby high-voltage side current transformer (18) accessed by a starting and standby transformer unit (4) of the bus differential protection (7) is enough to have a shunting phenomenon, checking whether the transformation ratio of the selected current transformer is consistent with a design value, checking whether the polarity of the accessed current is correct, and eliminating defects after confirmation.
8. A method for verifying the polarity of differential protection of a startup variable branch according to claim 4, wherein said step 6) comprises the steps of:
601) the standby high-voltage side current of the standby high-voltage side current transformer I (18) is reduced to zero, the motor field-suppression switch (11) is distributed, the field-suppression switch (11) is withdrawn to control the power supply, and the power supply of the excitation transformer (9) is disconnected;
602) separately opening a standby high-voltage side grounding disconnecting link (27) and quitting the control and power supply thereof;
603) checking that a starting-standby one-branch current loop of a starting-standby one-branch current transformer (21) and a starting-standby two-branch current loop of a starting-standby two-branch current transformer (24) are accurately connected, the ratio selection of the current transformers is consistent with the fixed value list, and a secondary loop has no open circuit phenomenon;
604) checking and confirming that the starting-standby branch A, B, C three-phase short circuit is completed by the short circuit device, the contact is good, and the starting-standby branch A, B, C three-phase short circuit is completed; checking and confirming that the starting-up and standby transformer two-branch short-circuit device 25 is installed and well contacted, and the three phases of the starting-up and standby transformer two-branch A, B, C are short-circuited through the short-circuit device;
605) the excitation transformer (9) is powered on, the de-excitation switch (11) is closed, the working mode of the excitation regulator (10) is adjusted to be in a manual state, and the low-voltage side branch of the start-up device has a through-flow condition.
9. A method for verifying the polarity of differential protection of a startup variable branch according to claim 4, wherein said step 9) comprises the steps of:
901) checking whether main transformer high-voltage side current of a starting-standby transformer high-voltage side current transformer II (19), starting-standby transformer branch current of a starting-standby transformer branch current transformer (21) and branch current of a starting-standby transformer branch current transformer (24) are consistent with a calculated value;
902) reading a starting-up transformer high-voltage side current of a starting-up transformer high-voltage side current transformer II (19), a starting-up transformer branch current transformer (21) and a starting-up transformer branch current of a starting-up transformer branch current transformer 24 in the starting-up transformer differential protection, and checking whether the starting-up transformer high-voltage side current and the starting-up transformer branch current are consistent with a measured value;
903) checking whether the differential current of the starting-standby transformer differential protection (8) is zero, and if the differential current is zero, considering that the polarity of the starting-standby transformer branch current of the connected starting-standby transformer branch current transformer (21) and the polarity of the two branch current of the starting-standby transformer branch current transformer (24) are correct; if the polarity is not zero, the polarity of the secondary current switched in by the starting-up branch unit (5) and the starting-up branch unit (6) is not correct.
10. A method for verifying the polarity of differential protection of a startup variable branch according to claim 4, wherein said step 10) comprises the steps of:
1001) reducing the current of the starting-standby transformer high-voltage side of a second current transformer (19) of the starting-standby transformer high-voltage side to zero, distributing a de-excitation switch (11) of the motor, withdrawing the control power supply of the de-excitation switch (11), and disconnecting the power supply of the excitation transformer 9;
1002) and checking whether the current on the low-voltage side of the start-up and standby transformer accessed by the start-up and standby transformer differential protection (8), the start-up and standby transformer one-branch unit (5) and the start-up and standby transformer two-branch unit (6) is enough to have a shunting phenomenon, checking whether the transformation ratio of the selected current transformer is consistent with a design value, checking whether the polarity of the accessed current is correct, and eliminating defects after confirmation.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112858958A (en) * | 2021-01-05 | 2021-05-28 | 中国神华能源股份有限公司国华电力分公司 | Method for detecting current wiring polarity of high-backup-power-transformation protection device |
| CN112965005A (en) * | 2021-02-04 | 2021-06-15 | 西安热工研究院有限公司 | System and method for verifying differential protection polarity by using dummy load |
| CN113964784A (en) * | 2021-10-28 | 2022-01-21 | 西安热工研究院有限公司 | System and method for single-phase one-time through-current correction of differential protection polarity and configuration of motor |
| CN114113821A (en) * | 2021-09-30 | 2022-03-01 | 华能太仓发电有限责任公司 | Incoming line current transformer wiring identification method for bus differential protection device |
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2020
- 2020-04-23 CN CN202010324959.6A patent/CN111366878A/en active Pending
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112858958A (en) * | 2021-01-05 | 2021-05-28 | 中国神华能源股份有限公司国华电力分公司 | Method for detecting current wiring polarity of high-backup-power-transformation protection device |
| CN112858958B (en) * | 2021-01-05 | 2023-02-28 | 中国神华能源股份有限公司国华电力分公司 | Method for detecting current wiring polarity of high-backup-power-transformation protection device |
| CN112965005A (en) * | 2021-02-04 | 2021-06-15 | 西安热工研究院有限公司 | System and method for verifying differential protection polarity by using dummy load |
| CN114113821A (en) * | 2021-09-30 | 2022-03-01 | 华能太仓发电有限责任公司 | Incoming line current transformer wiring identification method for bus differential protection device |
| CN114113821B (en) * | 2021-09-30 | 2024-02-27 | 华能太仓发电有限责任公司 | Wiring identification method for incoming line current transformer of bus differential protection device |
| CN113964784A (en) * | 2021-10-28 | 2022-01-21 | 西安热工研究院有限公司 | System and method for single-phase one-time through-current correction of differential protection polarity and configuration of motor |
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