CN112086938B - Converter transformer on-load tap-changer protection method based on electrical quantity - Google Patents
Converter transformer on-load tap-changer protection method based on electrical quantity Download PDFInfo
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- CN112086938B CN112086938B CN202010977155.6A CN202010977155A CN112086938B CN 112086938 B CN112086938 B CN 112086938B CN 202010977155 A CN202010977155 A CN 202010977155A CN 112086938 B CN112086938 B CN 112086938B
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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
- H02H7/22—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 distribution gear, e.g. bus-bar systems; for switching devices
- H02H7/222—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 distribution gear, e.g. bus-bar systems; for switching devices for switches
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
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Abstract
The invention discloses a method for protecting a converter transformer on-load tap-changer based on electrical quantity, which comprises the steps of collecting the electrical quantity, wherein the electrical quantity comprises CT current at a converter transformer sleeve and CT current in each sector of the on-load tap-changer; step two, calculating the acquired current, and judging the fault according to a set criterion; and step three, after the fault is judged, protecting the action and tripping off the switch. The method for protecting the on-load tap-changer of the converter transformer based on the electrical quantity can effectively improve the action speed of protection after the on-load tap-changer has a fault.
Description
Technical Field
The invention relates to a converter transformer on-load tap-changer protection method based on electrical capacity, and belongs to the technical field of converter transformer protection.
Background
The converter transformer is an important component of high-voltage and extra-high-voltage direct-current transmission. The voltage is regulated by adopting an on-load voltage regulation mode, the voltage regulation frequency is higher than that of a conventional transformer, and the failure rate of on-load tap-changer equipment is higher.
The common protection modes for internal faults of the on-load tap-changer at present are transformer ratio differential protection and non-electric quantity protection. The internal fault of the transformer on-load tap-changer is generally small in differential current, and at the moment, the ratio differential sensitivity is low, and the action speed is relatively slow. And non-battery protection may not be able to operate quickly in the event of a minor fault.
Although the differential current is very small when the on-load tap-changer has a fault, a large current may exist in the on-load tap-changer, and the conventional CT configuration cannot collect the large current in the on-load tap-changer at present, so that how to improve the protection precision of the internal fault of the on-load tap-changer is a problem which needs to be solved urgently by a person in the field.
Disclosure of Invention
The purpose is as follows: in order to overcome the defects in the prior art, the invention provides a converter transformer on-load tap-changer protection method based on electrical quantity.
The technical scheme is as follows: in order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a method for protecting a converter transformer on-load tap changer based on electrical quantity comprises the following steps:
collecting electrical quantity, including CT current at a converter transformer bushing and CT current in each sector of an on-load tap-changer;
step two, calculating the acquired current, and judging the fault according to a set criterion;
and step three, after the fault is judged, protecting the action and tripping the switch.
Preferably, the step one comprises the following steps:
the CT is arranged at the head end or the tail end of the converter transformer bushing, and the collected current is I3(ii) a The CT current in the on-load tap-changer is acquired by adopting an optical CT, two optical CTs are arranged in each sector of the on-load tap-changer, the first optical CT is arranged on a branch where a main on-off contact MSV is positioned, and the acquired branch current is
The second optical CT is arranged between a common point of the MC branch circuits of the two selection switches and a common point of the MC branch circuit of the selection switch and the MSV branch circuit of the main on-off contact, and the collected branch circuit current is
Where k is the sector number.
As a preferred scheme, the set criteria are divided into two types, and after any one of the two types of criteria is met, the fault criterion condition is met;
the first criterion is that the fundamental wave effective value of the sum of the first optical CT acquisition currents of each sector is divided by the fundamental wave effective value of the conventional CT acquisition current, the obtained result is greater than a first set fixed value, and the specific formula is as follows:
wherein f ([ lambda ]) represents a function for calculating the effective value of the fundamental wave of the current, and k is epsilon [1, n]；Im3Current representing conventional CT acquisition is I3Iset1 is the first set fixed value, Iset1 belongs to [1,2]]；
The second criterion is that the effective value of the fundamental wave of the sum of the current collected by the second optical CT of each sector is compared with a second set fixed value, and the obtained result is greater than the second set fixed value, wherein the specific formula is as follows:
wherein f (, represents a function for calculating the effective value of the current fundamental wave, and k belongs to [1, n ]; iset2 is the second setting value, and Iset2 takes 5-10 times of rated current value of the transformer.
Preferably, the CT current at the cannula is acquired using conventional CT.
Preferably, the first setting value is 1.2.
Preferably, the second setting value is a transformer rated current value 6 times.
Has the advantages that: the invention provides a method for protecting a converter transformer on-load tap changer based on electrical quantity, which is characterized in that an optical CT is arranged in the converter transformer on-load tap changer, and a conventional CT is arranged in a converter transformer sleeve; calculating the current collected by each CT, and judging the fault according to a set criterion; and after the fault judgment condition is met, the switch is tripped by protection action. The protection action speed after the on-load tap-changer has a fault can be effectively improved.
Drawings
Fig. 1 is a whole structure diagram of converter transformer and on-load tap-changer protection.
Fig. 2 is an internal structure diagram of the converter transformer on-load tap-changer.
Detailed Description
The present invention will be further described with reference to the following examples.
As shown in fig. 1, a method for protecting an electrical quantity-based converter transformer on-load tap changer includes the following steps:
collecting electrical quantity, including CT current at a converter transformer bushing and CT current in each sector of an on-load tap-changer;
step two, calculating the acquired current, and judging the fault according to a set criterion;
and step three, after the fault is judged, protecting the action and tripping off the switch.
Further, the step one is specifically: the CT current at the sleeve is collected by conventional CT which is arranged at the head end or tail end of the sleeve of the converter transformer, and the collected current is I3. The CT current in the on-load tap-changer is collected by optical CT, as shown in figure 2, two optical CTs are arranged in each sector of the on-load tap-changer, the first optical CT is arranged in the branch where the main on-off contact MSV is positioned, and the collected branch current is
The second optical CT is arranged between a common point of the two selection switch MC branches and a common point of the selection switch MC branch and the main on-off contact MSV branch, and the collected branch current is
Where k is the sector number.
Further, the second step specifically comprises: the set criteria are divided into two types, and the fault criterion condition is met after any one of the two types of criteria is met.
The first criterion is that the fundamental wave effective value of the sum of the first optical CT acquisition currents of each sector is divided by the fundamental wave effective value of the conventional CT acquisition current, the obtained result is greater than a set constant value 1, and a set constant value range [1,2] is used for ensuring that the protection does not act during normal operation. The concrete formula is as follows:
wherein f ([ lambda ]) represents a function for calculating the effective value of the fundamental wave of the current, and k belongs to [1, n ]]；Im3Current representing conventional CT acquisition is I3Iset1 is set to a fixed value of 1, Iset1 ∈ [1,2]]。
The second criterion is that the fundamental wave effective value of the sum of the second optical CT collected currents of each sector is compared with a set value 2, the obtained result is greater than the set value 2, and the set value 2 is 5-10 times of the rated current value of the transformer and is used for avoiding the maximum magnetizing inrush current of the transformer.
Wherein f (, represents a function for calculating the effective value of the current fundamental wave, and k belongs to [1, n ]; iset2 is set to be a fixed value 2, and Iset2 is 5-10 times of the rated current value of the transformer.
The embodiment is as follows:
take the converter transformer on-load tap-changer with two sectors as an example.
A method for protecting a converter transformer on-load tap changer based on electrical quantity comprises the following steps:
step one, collecting current I at the front end of a sleeve of a converter transformer3Collecting current at the installation positions of the first optical CT and the second optical CT in two sectors of the on-load tap-changer
In each sector, a first optical CT is installed in the branch where the main on-off contact MSV is located, and a second optical CT is installed between the common point of the two selection switch MC branches and the common point of the selection switch MC branch and the main on-off contact MSV branch.
And step two, calculating the acquired current, and judging the fault according to a set criterion.
The method comprises the following specific steps: the set criteria are divided into two types, and after any one of the two types of criteria is met, the fault criterion condition is met.
The first criterion is that the sum of effective fundamental wave values of the current collected by the first optical CTs of the two sectors is divided by the effective fundamental wave value of the current at the sleeve, and the obtained result is greater than a set fixed value 1.
The specific calculation formula is as follows:
wherein, the first and the second end of the pipe are connected with each other,
the current acquired for the first optical CT in sector 1,
the current acquired for the first optical CT in sector 2,
effective value of the fundamental wave, Im, of the sum of the currents collected for the first optical CT of sectors 1,23Is the effective value of the current fundamental wave at the sleeve. Iset1 was set to constant 1, and Iset1 was 1.2.
The second criterion is that the sum of effective values of fundamental waves of current collected by the second optical CT of the two sectors is compared with a set fixed value 2, and the obtained result is greater than the set fixed value 2.
The specific calculation formula is as follows:
wherein the content of the first and second substances,
the current acquired for the second optical CT in sector 1,
the current acquired for the second optical CT in sector 2,
the fundamental value of the sum of the currents acquired for the second optical CT of sectors 1, 2. Iset2 is set to be constant value 2, and Iset2 is set to be 6 times of rated current value of the transformer.
And step three, after the fault is judged, protecting the action and tripping off the switch.
The above description is only of the preferred embodiments of the present invention, and it should be noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the invention, and such modifications and adaptations are intended to be within the scope of the invention.
Claims (4)
1. A method for protecting a converter transformer on-load tap-changer based on electrical quantity is characterized by comprising the following steps: the method comprises the following steps:
collecting electrical quantity, including CT current at a converter transformer bushing and CT current in each sector of an on-load tap-changer;
step two, calculating the acquired current, and judging the fault according to a set criterion;
step three, after the fault is judged, the protection action is carried out, and the switch is tripped;
the first step comprises the following specific steps:
the CT is arranged at the head end or the tail end of the converter transformer bushing, and the collected current is I3(ii) a The CT current in the on-load tap-changer is acquired by adopting an optical CT, two optical CTs are arranged in each sector of the on-load tap-changer, the first optical CT is arranged on a branch where a main on-off contact MSV is positioned, and the acquired branch current is
The second optical CT is arranged between a common point of the two selection switch MC branches and a common point of the selection switch MC branch and the main on-off contact MSV branch, and the collected branch current is
Wherein k is the serial number of the sector;
the set criteria are divided into two types, and after any one of the two types of criteria is met, the fault criterion condition is met;
the first criterion is that the fundamental wave effective value of the sum of the first optical CT acquisition currents of each sector is divided by the fundamental wave effective value of the conventional CT acquisition current, the obtained result is greater than a first set fixed value, and the specific formula is as follows:
wherein f ([ lambda ]) represents a function for calculating the effective value of the fundamental wave of the current, and k belongs to [1, n ]]；Im3Current representing a conventional CT acquisition is I3Is the first set constant value, Iset1, Iset1 ∈ [1,2]]；
The second criterion is that the effective value of the fundamental wave of the sum of the current collected by the second optical CT of each sector is compared with a second set fixed value, and the obtained result is greater than the second set fixed value, wherein the specific formula is as follows:
wherein, f ([ lambda ]) represents a function for calculating the effective value of the current fundamental wave, and k belongs to [1, n ]; iset2 is a second set value, and Iset2 takes the rated current value of the transformer of 5-10 times.
2. The method according to claim 1, wherein the method comprises the following steps: the CT current at the cannula is acquired using conventional CT.
3. The electrical quantity based converter transformer on-load tap changer protection method according to claim 1, characterized in that: the first set fixed value is 1.2.
4. The electrical quantity based converter transformer on-load tap changer protection method according to claim 1, characterized in that: and the second set fixed value is 6 times of the rated current value of the transformer.
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| CN202010977155.6A CN112086938B (en) | 2020-09-16 | 2020-09-16 | Converter transformer on-load tap-changer protection method based on electrical quantity |
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| CN114512956A (en) * | 2022-03-15 | 2022-05-17 | 南京南瑞继保电气有限公司 | Transformer tap switch protection method based on built-in current and temperature sensor |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104269827A (en) * | 2014-10-15 | 2015-01-07 | 南京南瑞继保电气有限公司 | Locking method for large-difference percentage differential protection magnetizing inrush current of converter transformer |
| CN107611938A (en) * | 2017-10-24 | 2018-01-19 | 南京国电南自电网自动化有限公司 | A kind of method that bus protection distinguishes high resistive fault and CT broken strings |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104269827A (en) * | 2014-10-15 | 2015-01-07 | 南京南瑞继保电气有限公司 | Locking method for large-difference percentage differential protection magnetizing inrush current of converter transformer |
| CN107611938A (en) * | 2017-10-24 | 2018-01-19 | 南京国电南自电网自动化有限公司 | A kind of method that bus protection distinguishes high resistive fault and CT broken strings |
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