CN103618290A - Transformer dead-zone fault relay protection method based on short-time open protection and sealed TAs - Google Patents

Abstract

The invention relates to a transformer dead zone fault relay protection method based on short-time open protection and sealing TA. In this method, the following conditions are set in the tripping control of the dead zone fault on a certain side of the transformer: Condition 1, the backup protection trip outlet relay on this side of the transformer is in the action state or the trip outlet relay of other electrical quantity protection is in the action state; Condition 2, when the condition When one is met, start a pulse T time open protection; condition three, the current Ipmax of phase A or B or C on the side of the transformer reaches the starting value, or the zero-sequence current Io or negative-sequence current _I2 reaches the starting value, that is, ≥ setting value; when the above conditions are met, exit the transformer differential protection TA on this side of the transformer after a delay; when any of the above conditions are not satisfied or after the opening protection time T is reached, 0s is connected to the transformer differential protection TA on this side of the transformer. The invention has simple action principle, high reliability, and can quickly cut off faults in dead zones of various voltage levels on each side of the transformer.

Description

Transformer dead zone fault relay protection method based on short-time open protection and closed TA

technical field

The invention belongs to the control technology of electric power transmission and distribution network, and relates to a transformer dead zone fault relay protection method based on short-time open protection and sealing TA.

Background technique

GB/T 14285-2006 "Technical Regulations for Relay Protection and Safety Automatic Devices" stipulates that the transformer should be equipped with longitudinal differential protection as the main protection and the back-up protection of the transformer over-current caused by external phase-to-phase short-circuit and grounding short-circuit. , where the backup protection for responding to phase-to-phase short circuit includes composite voltage overcurrent protection and phase-to-phase impedance protection, and the backup protection for responding to grounding short circuit includes zero-sequence current protection and grounding impedance protection. These backup protections are equipped with different backup protections according to the voltage levels of transformers of different voltage levels and the voltage levels of each side, and generally all sides of the transformer are equipped with backup protections that respond to external phase-to-phase short-circuits and grounding short-circuits. The protection configuration of 220kV and above transformers is specified in Q/GDW_175 "Standardized Design Specifications for Transformers, High-voltage Shunt Reactors, Busbar Protection and Auxiliary Devices"; Composite voltage overcurrent protection (if the 110kV neutral point is generally not grounded, the zero-sequence current protection is generally not used, and only the 110kV neutral point gap protection is used; if the 110kV neutral point is generally grounded, the zero-sequence current protection is configured Current protection is used, 110kV neutral point gap protection is disabled).

The so-called transformer dead-zone fault refers to the short-circuit fault that occurs between the circuit breaker on one side of the transformer and the current transformer (hereinafter referred to as TA) used for the differential protection of the transformer on this side (see Figure 2). Since the fault is outside the protection range of the transformer longitudinal differential protection, although the backup protection or other protection (such as busbar protection) on the fault side operates to trip the circuit breaker on the side of the transformer, the fault still exists. The protection action or the backup protection action of this side is used to trip the general outlet circuit of the transformer and trip the circuit breaker on the power side of the transformer to finally remove the fault. In this case, the time to remove the fault is generally longer; Since the short-circuit current does not reach the start-up fixed value, the fault cannot be removed. Only when the transformer is burned to the point that the short-circuit current reaches and exceeds the backup protection start-up value can the backup protection on the power supply side of the transformer be activated to remove the fault. Invention patent 201210452783.8 "Relay Protection Method for Quickly Removing Transformer Dead Zone Faults" proposes a scheme to exit the transformer differential protection side TA after judging the dead zone fault, so that the transformer differential protection action trips the other side circuit breaker. . The present invention will propose an improved logic circuit to complete the transformer protection device suitable for the transformer substations of various voltage levels of the applied power transmission and distribution network and quickly cut off the relay protection technical scheme of dead zone faults of various voltage levels on each side of the transformer .

Contents of the invention

The problem to be solved by the present invention is to provide a transformer protection device that can be applied to power transmission and distribution networks for substations with various voltage levels. method of relay protection.

Provide the technical scheme of the inventive method below.

The substation of the power transmission and distribution network applied in the method of the present invention is a protective device for two-winding transformers, three-winding transformers, autotransformers or other transformers of various voltage levels; in theory, the transformer has several operating voltages The level is connected to the external circuit equipment through the circuit breaker interval equipment (composed of isolating switch, circuit breaker, current transformer and other equipment), as long as there is only a current transformer (TA for short) on both sides of the circuit breaker on one side of the transformer, If there is no TA on the busbar side, there are several transformer dead-zone fault locations (if there are TAs on both sides of the circuit breaker, the circuit breaker circuit has no dead-zone fault locations), that is, there are two operating voltage levels passing through the circuit breaker interval equipment If it is connected to the external circuit equipment, there are at least 2 transformer dead zone fault positions; if there are 3 operating voltage levels connected to the external circuit equipment through the circuit breaker spacer, there are at least 3 transformer dead zone fault positions (1 operating voltage level If there are 2 circuit breaker interval devices, then the operating voltage level side is 2 transformer dead zone fault positions).

For the convenience of description, the transformer dead-zone fault occurs in the circuit breaker interval equipment of one of the operating voltage levels of the transformer, and the method of quickly starting to remove the fault is described. The transformers of other voltage levels and the transformers are two-winding transformers, three-winding transformers, automatic Coupling transformer or other transformers, or the combination of other voltage levels on each side of the transformer, the method is similar and will not be repeated here. The circuit breaker interval equipment is composed of isolating switch, circuit breaker, TA and other equipment. TA has several sets of secondary windings respectively. These sets of secondary windings are respectively connected to transformer differential protection (backup protection) from the bus side to the transformer side. Secondary equipment such as busbar differential protection, measurement and metering. A bushing TA is also installed at the bushing of the transformer. The TA used for the backup protection on each side of the transformer of 110kV and below is separate from the transformer differential protection, and the TA used is different (for example, the differential protection uses the TA at the circuit breaker, while the backup protection uses the bushing TA), or TA different secondary windings. Its control method includes the following control process:

In the trip control of the dead zone fault on one side of the transformer, the following conditions are set:

Condition 1: The trip outlet relay of the backup protection on this side of the transformer is in action or the trip outlet relay of other electrical quantity protections (such as bus differential protection on this side) is in action;

Condition 2, when condition 1 is met, start a pulse T time open protection (that is, only open protection T time; T can be 2t1, that is, 300ms, the same below);

Condition 3: The A-phase or B-phase or C-phase current Ipmax on this side of the transformer reaches the start-up value, or the zero-sequence current Io or negative-sequence current _I2 reaches the start-up value, that is, ≥ the set value;

When the above conditions are met, the transformer differential protection TA on this side of the transformer will be exited after a delay of t1 (such as 150ms), that is, the current on this side of the transformer will not participate in the calculation of the transformer differential protection current; when any of the above conditions is not satisfied, or open the protection After the time T arrives, 0s is connected to the transformer differential TA on this side of the transformer, that is, the current on this side of the transformer participates in the calculation of the transformer differential protection current.

Since the transformer differential protection withdraws the current on the fault side from the calculation of the transformer differential protection current, it is equivalent to changing the comprehensive differential current of the transformer differential protection from 0 or very small to the short-circuit current of the short-circuit point, which makes the transformer differential protection take the fault If an external fault is judged as an internal fault, the differential protection of the transformer will activate the tripping circuit of the transformer general outlet, trip other circuit breakers of the transformer, and cut off the fault.

To judge that there is still current in phase A, B or C on this side of the transformer, the differential protection TA current on this side of the transformer can be collected, and the current setting can be set according to avoiding the maximum load current on this side of the transformer; system, the zero-sequence current or negative-sequence current setting can be set according to the sufficient sensitivity of the grounding fault of the busbar on the side of the transformer (the sensitivity coefficient can be ≥3).

When the voltage level on one side of the transformer is 35kV and below, the system is generally an ungrounded system or a grounded system through an arc suppression coil, and the zero-sequence current criterion on this side of the transformer may not be used. If it is a resistance-grounded system, the zero-sequence current criterion on this side of the transformer can be used.

Compared with the existing method for removing transformer dead zone faults, the present invention has the following advantages:

1. It is suitable for the technical scheme of transformer protection devices such as two-winding transformers, three-winding transformers, and autotransformers of various voltage levels for substations in power transmission and distribution networks.

2. After judging the dead zone fault, the method uses a delay to exit the transformer differential TA on the transformer fault side, that is, the current on the transformer fault side does not participate in the calculation of the transformer differential protection current. The criterion is simple and practical; after judging the dead zone fault, the comparison After a short delay, the differential protection of the transformer is quickly started, and the purpose of quickly removing the dead zone fault is achieved;

3. Since the breaker opening position contact is not included in the criterion, for a bus fault on one side of the substation, the bus protection action or the backup protection action on the transformer fault side, but the circuit breaker on the transformer fault side refuses to operate (circuit breaker failure), this The inventive scheme can also exit the transformer differential TA on the transformer fault side after a delay of t1 (150 ms) after judging that the circuit breaker refuses to operate, start the transformer differential protection, and quickly remove the fault.

4. The T time loop of short-time open protection is added, which enhances the safety of the transformer dead zone fault protection.

Description of drawings

Fig. 1 is the logic diagram of differential TA of the transformer on one side of the transformer in the method of the present invention, starting and exiting from the dead zone fault of the transformer on this side;

Figure 2 is a part of the primary main wiring diagram of a 220kV substation.

The symbols in Figure 1 are explained as follows:

表示逻辑与关系，即输入条件全部满足时，输出有效；

Indicates a logical AND relationship, that is, when all input conditions are met, the output is valid;

-表示逻辑或关系，即输入条件任一满足时，输出有效；

-Represents a logical or relationship, that is, when any of the input conditions is satisfied, the output is valid;

-表示输入条件满足延时150毫秒，输入条件不满足0秒返回；

-Indicates that the input condition is satisfied and the delay is 150 milliseconds, and the input condition is not satisfied and the return is 0 seconds;

-表示300ms脉冲输出。

- means 300ms pulse output.

Detailed ways

Taking the protection of a 220kV autotransformer in a 220kV substation as an example, to describe the method of quickly starting and removing the fault in the dead zone of the transformer, the transformers of other voltage levels, and the transformers are two-winding transformers, three-winding For other transformers, or combinations of other voltage levels on each side of the transformer, the methods are similar and will not be repeated here. As shown in Figure 2, it is part of the primary main wiring diagram of a 220kV substation, a 220kV autotransformer, and the transformer is equipped with a high-voltage side circuit breaker 1QF, a medium-voltage side circuit breaker 2QF, and a low-voltage side circuit breaker 3QF; the high-voltage side circuit breaker A set of independent TAs are respectively installed at 1QF of the transformer, 2QF of the medium-voltage side circuit breaker, and 3QF of the low-voltage side circuit breaker. The TAs have several sets of secondary windings respectively. A casing TA is set. The TA configuration on each side of the 220kV transformer is shown in Figure 2, in which the secondary winding of the TA at the high-voltage side of the transformer (220kV) circuit breaker is respectively connected from the busbar side to the transformer side with the first set of transformer longitudinal differential and backup protection, and the second set of Transformer longitudinal differential and backup protection (220kV transformer protection generally adopts the integrated configuration of main protection and backup protection, that is, each side of the main protection and backup protection shares the same set of TA secondary windings and voltage transformer secondary windings, and the main protection and backup protection All hardware equipment and software of backup protection are in the same chassis), the first set of 220kV bus differential protection, the second set of 220kV bus differential protection (according to Q/GDW_175 "transformer, high voltage shunt reactor and bus protection and auxiliary device standardization The transformer protection designed in Design Specification does not have a special circuit breaker failure current circuit, which is realized by bus differential protection; otherwise, a special circuit breaker failure current circuit is set), metering, measurement; The TA secondary winding is respectively connected with the first set of transformer longitudinal differential and backup protection, the second set of transformer longitudinal differential and backup protection, 110kV bus differential protection, metering and measurement from the bus side to the transformer side; the transformer low-voltage side (35kV or 10kV, etc.) The TA secondary winding at the circuit breaker is respectively connected from the busbar side to the transformer side with the first set of transformer longitudinal differential and backup protection, the second set of transformer longitudinal differential and backup protection (busbar protection), Fault recording, measurement, measurement, etc.

Provide below the embodiment that the inventive method is applied to transformer dead zone fault and removes this fault fast:

1. Quick removal method of transformer high voltage side dead zone fault

(1) When a phase-to-phase short circuit or ground fault occurs between the transformer high-voltage side circuit breaker lQF and the high-voltage side TA used for transformer differential protection (that is, the TA at the high-voltage side circuit breaker), the fault is within the scope of the transformer’s longitudinal differential protection outside, but within the protection range of the first set of 220kV bus differential protection and the second set of 220kV bus differential protection, the first set of 220kV bus differential protection and the second set of 220kV bus differential protection start to trip all the faulty buses Switch (including transformer high voltage side circuit breaker lQF). If there is power supply on the other side of the transformer, although the circuit breaker 1QF has tripped, the fault has not been removed, and the fault phase still has a certain phase current or zero-sequence current or negative-sequence current exceeding the set value, so the first set of 220kV bus differential protection, the second The second set of 220kV busbar differential protection still operates and does not return (or the backup protection on the high voltage side of the transformer is delayed until the backup protection still operates and does not return), and the open protection circuit is started for 300ms, so the three conditions for judging the dead zone fault are met, and the delay After t1 is 150ms, exit the transformer differential TA at the high voltage side of the transformer, that is, the current at the high voltage side of the transformer does not participate in the calculation of the transformer differential protection current. Since the transformer differential protection removes the current on the fault side from the calculation of the transformer differential protection current, it is equivalent to changing the comprehensive differential current of the transformer differential protection from 0 or very small to the short-circuit current of the short-circuit point, which makes the transformer differential protection judge the dead zone When the fault changes from an external fault to an internal fault, the differential protection of the transformer will activate the tripping circuit of the transformer general outlet, trip other circuit breakers of the transformer, and remove the fault.

(2) When the high-voltage side circuit breaker lQF of the transformer has already occurred the dead zone fault on the high-voltage side of the transformer at the opening position, the fault is outside the scope of the transformer longitudinal differential protection, but the first set of 220kV bus differential protection, the second set Within the protection range of 220kV bus differential protection, the first set of 220kV bus differential protection and the second set of 220kV bus differential protection start to trip all switches of the faulty bus. If there is power supply on the other side of the transformer, although the circuit breaker 1QF is already in the opening position, but the fault phase has short-circuit current or zero-sequence current or negative-sequence current exceeding the set value, the first set of 220kV bus differential protection, the second set of 220kV bus differential protection When the delay time of the active protection action or the start-up delay time of the backup protection on the high-voltage side of the transformer is up, the 300ms circuit of the open protection is started, so the three conditions for judging the dead zone fault are met. The transformer high-voltage side current does not participate in the calculation of the transformer differential protection current. Since the transformer differential protection removes the current on the fault side from the calculation of the transformer differential protection current, it is equivalent to changing the comprehensive differential current of the transformer differential protection from 0 or very small to the short-circuit current of the short-circuit point, which makes the transformer differential protection judge the dead zone When the fault changes from an external fault to an internal fault, the differential protection of the transformer will activate the tripping circuit of the transformer general outlet, trip other circuit breakers of the transformer, and remove the fault.

(3) If it is a 220kV bus fault, although the two sets of 220kV bus differential protections operate, the two sets of 220kV bus differential protections start to trip all other switches of the faulty bus, but the transformer high-voltage side circuit breaker lQF refuses to operate. If there is power supply, the fault is not cut off, and the fault phase still has current or the zero-sequence current or negative-sequence current exceeds the set value, so the first set of 220kV bus differential protection and the second set of 220kV bus differential protection still operate without returning (or the transformer The backup protection on the high-voltage side starts to delay until the backup protection still does not return), start the open protection circuit for 300ms, so the three conditions for judging the dead zone fault are met, and after the delay t1 is 150ms, exit the transformer differential TA on the high-voltage side of the transformer, That is, the transformer high-voltage side current does not participate in the calculation of the transformer differential protection current. Since the transformer differential protection removes the current on the fault side from the calculation of the transformer differential protection current, it is equivalent to changing the comprehensive differential current of the transformer differential protection from 0 or very small to the short-circuit current of the short-circuit point, which makes the transformer differential protection judge the dead zone When the fault changes from an external fault to an internal fault, the differential protection of the transformer will activate the tripping circuit of the transformer general outlet, trip other circuit breakers of the transformer, and remove the fault.

(4) If there is no power supply on the other side of the transformer in the substation, there will be no fault current flowing on the fault side of the transformer. Therefore, if the three conditions for judging the dead zone fault are not satisfied, the transformer differential TA on the high voltage side of the transformer will not be activated and exited. If the 220kV busbar differential protection or the backup protection on the high-voltage side of the transformer keeps acting and does not return, the dead zone protection of the transformer will be blocked after 300ms and an alarm signal will be issued.

2. Quick removal method for dead zone faults on the medium voltage side of transformers

(1) When a phase-to-phase short circuit or ground fault occurs between the transformer medium-voltage side circuit breaker 2QF and the medium-voltage side TA used for transformer differential protection (that is, the TA at the medium-voltage side circuit breaker), the fault occurs in the transformer longitudinal differential Outside the protection range, but within the protection range of the 110kV bus differential protection, the 110kV bus differential protection starts to trip all the switches of the faulty bus (including the circuit breaker 2QF on the medium voltage side of the transformer), although the circuit breaker 2QF has tripped, But the fault is not cut off, the fault phase still has current or the zero-sequence current or negative-sequence current exceeds the set value, so the 110kV bus differential protection still operates and does not return (or the backup protection on the medium voltage side of the transformer still does not operate after the start-up delay time expires) Return), start the open protection circuit for 300ms, so the three conditions for judging the dead zone fault are met, and after the delay t1 is 150ms, exit the transformer differential TA on the medium voltage side of the transformer, that is, the current on the medium voltage side of the transformer does not participate in the differential protection current of the transformer calculate. Since the transformer differential protection removes the current on the fault side from the calculation of the transformer differential protection current, it is equivalent to changing the comprehensive differential current of the transformer differential protection from 0 or very small to the short-circuit current of the short-circuit point, which makes the transformer differential protection judge the dead zone When the fault changes from an external fault to an internal fault, the differential protection of the transformer will activate the tripping circuit of the transformer general outlet, trip other circuit breakers of the transformer, and remove the fault.

(2) When the transformer medium voltage side circuit breaker 2QF has occurred in the open position of the transformer medium voltage side dead zone fault, the fault is outside the transformer longitudinal differential protection range, but within the 110kV bus differential protection protection range, The 110kV bus differential protection starts to trip all the switches of the faulty bus. Although the circuit breaker 2QF is in the opening position, but the fault phase has a short-circuit current or zero-sequence current or negative-sequence current exceeding the set value, the 110kV bus differential protection operates or the start-up delay time of the backup protection on the medium-voltage side of the transformer expires, and the start-up is opened The 300ms circuit is protected, so the three conditions for judging the dead zone fault are satisfied, and after the delay t1 is 150ms, the transformer differential TA on the medium voltage side of the transformer is exited, that is, the current on the medium voltage side of the transformer does not participate in the calculation of the transformer differential protection current. Since the transformer differential protection removes the current on the fault side from the calculation of the transformer differential protection current, it is equivalent to changing the comprehensive differential current of the transformer differential protection from 0 or very small to the short-circuit current of the short-circuit point, which makes the transformer differential protection judge the dead zone When the fault changes from an external fault to an internal fault, the differential protection of the transformer will activate the tripping circuit of the transformer general outlet, trip other circuit breakers of the transformer, and remove the fault.

(3) If it is a 110kV bus fault, although the 110kV bus differential protection operates, the 110kV bus differential protection starts to trip all other switches of the faulty bus, but the medium-voltage side circuit breaker 2QF of the transformer refuses to operate, but the fault has not been removed, and the fault phase There is still current or the zero-sequence current or negative-sequence current exceeds the setting value, so the 110kV bus differential protection still operates and does not return (or the backup protection still operates and does not return after the start-up delay time of the backup protection on the medium voltage side of the transformer), start the open protection for 300ms circuit, so the three conditions for judging the dead zone fault are satisfied, after the delay t1 is 150ms, that is, the current on the medium voltage side of the transformer does not participate in the calculation of the transformer differential protection current. Since the transformer differential protection removes the current on the fault side from the calculation of the transformer differential protection current, it is equivalent to changing the comprehensive differential current of the transformer differential protection from 0 or very small to the short-circuit current of the short-circuit point, which makes the transformer differential protection judge the dead zone When the fault changes from an external fault to an internal fault, the differential protection of the transformer will activate the tripping circuit of the transformer general outlet, trip other circuit breakers of the transformer, and remove the fault.

(4) If the 110kV busbar differential protection or the backup protection on the high voltage side of the transformer keeps acting and does not return, the dead zone protection of the transformer will be blocked after 300ms and an alarm signal will be issued.

3. Quick removal method for dead zone faults on the low voltage side of transformers

(1) The voltage level of the low-voltage side of the transformer is generally 35kV and below. The system is generally an ungrounded system or a grounded system through an arc suppression coil or a grounded system through a resistance. Generally, no special bus differential protection is installed, and one of them The backup protection on the low-voltage side of the transformer is used as the busbar protection. When a phase-to-phase short circuit or ground fault occurs between the transformer low-voltage side circuit breaker 3QF and the low-voltage side TA used for transformer differential protection (that is, the TA at the low-voltage side circuit breaker) Out of the range of dynamic protection, but within the protection range of the backup protection on the low-voltage side of the transformer, the backup protection on the low-voltage side of the transformer starts to trip the circuit breaker 3QF on the low-voltage side of the transformer. Although the circuit breaker 3QF has tripped, the fault has not been cut off, and the fault phase still has current or the negative sequence current or zero sequence current exceeds the set value (when the system is grounded by resistance), so the differential protection of the low-voltage bus still operates and does not return (or the transformer The low-voltage side backup protection (when there is no busbar protection, one of the low-voltage side backup protections is used as the busbar protection) starts the delay time and the backup protection still does not return), and the open protection circuit is started for 300ms, so it is judged that the three faults in the dead zone If the first condition is satisfied, after the delay t1 is 150ms, the transformer differential TA on the low-voltage side of the transformer is exited, that is, the current on the low-voltage side of the transformer does not participate in the calculation of the transformer differential protection current. Since the transformer differential protection withdraws the fault side current from the calculation of the transformer differential protection current, the fault in the dead zone changes from a fault outside the differential protection zone of the transformer to a fault inside the zone, and the transformer differential protection activates the tripping circuit of the transformer general outlet, tripping Transformer and other circuit breakers cut off the fault.

(2) When the above-mentioned low-voltage side dead zone fault occurs on the low-voltage side circuit breaker 3QF of the transformer at the opening position, the fault is outside the transformer longitudinal differential protection range, but within the protection range of the transformer low-voltage side backup protection. The backup protection on the low-voltage side starts; although the circuit breaker 3QF is already in the opening position, there is still current in the fault phase or the negative-sequence current or zero-sequence current exceeds the set value (when passing through the resistance grounding system), when the backup protection on the low-voltage side of the transformer is back-up on the low-voltage side The protection start delay time action, start the open protection 300ms circuit, so the three conditions for judging the dead zone fault are satisfied, after the delay t1 is 150ms, exit the transformer differential TA on the low voltage side of the transformer, that is, the current on the low voltage side of the transformer does not participate in the transformer differential Protection current calculation. Since the transformer differential protection withdraws the fault side current from the calculation of the transformer differential protection current, the fault in the dead zone changes from a fault outside the differential protection zone of the transformer to a fault inside the zone, and the transformer differential protection activates the tripping circuit of the transformer general outlet, tripping Transformer and other circuit breakers cut off the fault.

(3) If it is a low-voltage bus fault, although the backup protection on the low-voltage side of the transformer operates, the circuit breaker 2QF on the low-voltage side of the transformer refuses to operate, so the fault is not removed, and the fault phase still has current or the negative sequence current exceeds the set value. The backup protection on the low-voltage side of the transformer When the start-up delay time reaches the backup protection and still does not return, start the open protection circuit for 300ms, so the three conditions for judging the dead zone fault are met, and after the delay t1 is 150ms, exit the transformer differential TA on the low-voltage side of the transformer, that is, the current on the low-voltage side of the transformer It does not participate in the calculation of transformer differential protection current. Since the transformer differential protection withdraws the fault side current from the calculation of the transformer differential protection current, the fault in the dead zone changes from a fault outside the differential protection zone of the transformer to a fault inside the zone, and the transformer differential protection activates the tripping circuit of the transformer general outlet, tripping Transformer and other circuit breakers cut off the fault.

(4) If the backup protection on the low-voltage side of the transformer keeps acting and does not return, the dead-zone protection of the transformer will be blocked after 300ms, and an alarm signal will be issued.

4. Quick removal method for other transformer dead zone faults

When the voltage level on one side of the transformer is 35kV or below, the system is generally an ungrounded system or a grounded system through an arc suppressing coil or a grounded system through a resistance. The quick removal method of the dead zone fault on this side of the transformer can refer to the dead zone on the low voltage side of the 220kV transformer. Area fault quick removal method.

When the voltage level on one side of the transformer is 110kV or 220kV and above, the system is generally an effective grounding system, and the quick removal method of the dead zone fault on this side of the transformer can refer to the quick removal method of the dead zone fault on the high voltage side or medium voltage side of the 220kV transformer.

When the transformer is a two-winding transformer, it is equivalent to the lack of one side of the above-mentioned three-winding transformer, and it is only necessary to consider the method of quick removal of dead zone faults on both sides of the transformer.

Claims (1)

1. A transformer dead-zone fault relay protection method based on short-time open protection and sealing TA, is characterized in that: in the tripping control of a certain side dead zone fault of the transformer, the following conditions are set, Condition 1, the backup protection trip outlet relay on the side of the transformer is in action or the trip outlet relay of other electrical quantity protection is in action; Condition two, when condition one is met, start a pulse T time open protection; Condition 3: The A-phase or B-phase or C-phase current Ipmax on this side of the transformer reaches the start-up value, or the zero-sequence current Io or negative-sequence current I ₂ Reach the starting value, that is, ≥ the setting value; When the above conditions are met, exit the transformer differential protection TA on this side of the transformer after a delay of t1, that is, the current on this side of the transformer does not participate in the calculation of the transformer differential protection current; when any of the above conditions is not satisfied or after the open protection time T is reached , 0s is connected to the transformer differential TA on this side of the transformer, that is, the current on this side of the transformer participates in the calculation of the transformer differential protection current.

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