A relay protection method for bypass circuit breaker failure protection

Abstract

The present invention discloses a relay protection method for bypass circuit breaker failure protection, which solves the technical problem that the bypass circuit breaker failure protection in the bypass line and bypass transformer operation mode cannot be realized in a 220kV substation with a double busbar and bypass busbar connection. The present invention adopts the method of connecting the secondary current of the 220kV bypass circuit breaker CT and the line protection opening signal to the line branch in the six unified busbar protection to form the bypass circuit breaker failure protection of the bypass circuit breaker in the bypass line mode. By switching the pressure plate, the No. 1 and No. 2 transformer protection opening signals and the bypass circuit breaker CT secondary current can also be connected to the vacant transformer branch in the six unified busbar protection to form the bypass circuit breaker failure protection of the bypass circuit breaker in the bypass transformer mode. In the bypass line or transformer mode, the bypass circuit breaker is prevented from operating without failure protection, and the fault can be quickly cut off, thereby ensuring the safe and stable operation of the power grid and improving the power supply reliability of the power grid.

Description

Technical Field

[0001] The present invention relates to a relay protection method for bypass circuit breaker failure protection in a 220kV double-busbar with bypass busbar connection substation, in which the bypass circuit breaker replaces the line circuit breaker and the transformer circuit breaker respectively. The present invention belongs to the protection and control technology of the power transmission and distribution network. Background Art

[0002] At present, the 220kV side main connection of the 220kV substation is a double busbar with a bypass busbar. When the 220kV busbar protection adopts six unified standardized devices, the circuit breaker failure protection is generally integrated into the busbar protection. The busbar protection includes the current circuit of each branch, the auxiliary contacts of the busbar disconnectors of each branch section I and II, the opening circuit of the protection tripping contact to start the failure protection, the bus differential logic circuit, the failure start logic circuit and the tripping circuit; among them, the connection circuits between external protection equipment and busbar protection are: the current circuit of each branch, the opening circuit of the protection tripping contact to start the failure protection, the opening circuit and tripping circuit of the auxiliary contacts of the disconnector position on the busbar side of each branch I and II; the failure start logic circuit has line branch and transformer branch logic respectively, all of which are implemented in the busbar protection. The line branch failure initiation logic circuitry combines single-phase and three-phase tripping modes. The transformer branch failure initiation logic circuitry combines three-phase tripping modes. Current discrimination in the failure protection initiation logic is also implemented in the busbar protection, sharing the same current transformer secondary winding current as the busbar differential protection. The current discrimination and protection tripping contacts of each branch together constitute the failure protection initiation circuitry for that branch.

[0003] The failure protection logic of the 220kV bypass circuit breaker is generally designed according to the operation mode of the 220kV bypass circuit breaker replacing the 220kV line circuit breaker (hereinafter referred to as the bypass line). In this operation mode, the bypass circuit breaker failure protection is enabled. However, this logic has the following problems when the bypass circuit breaker replaces the transformer circuit breaker (hereinafter referred to as the bypass transformer): (1) The bypass circuit breaker failure protection logic is the same as the line branch circuit breaker failure protection logic, which cannot adapt to the operation mode of the bypass transformer; (2) The tripping contact of the transformer protection is not connected to the failure circuit of the 220kV bypass circuit breaker. When the transformer protection is activated, the 220kV bypass circuit breaker failure protection is not activated; (3) In the bypass transformer mode, since the transformer protection changes from tripping the own circuit breaker to tripping the bypass circuit breaker, the bypass circuit breaker's own protection needs to be disabled. In summary, in the bypass transformer circuit breaker mode, the bypass circuit breaker failure protection is not able to adapt to the bypass transformer operation mode because the protection logic cannot adapt to the bypass transformer operation mode.

[0004] In summary, the busbar protection designed using the six unified standards can be normally enabled in the bypass line mode due to the matching of the failure logic function. However, the implementation method of the bypass breaker failure protection in the bypass transformer mode is not considered, so the protection needs to be disabled. If the transformer fails at this time and the bypass breaker fails, the fault cannot be cleared by the bypass breaker failure protection and can only be cleared by the backup protection of other equipment in the power grid. First, the clearing time is long, affecting the safe and stable operation of the power grid. Second, it violates the relevant provisions of DL / T 559 "220kV~750kV Power Grid Relay Protection Device Operation and Setting Regulations" and "State Grid Corporation of China's Eighteen Major Power Grid Anti-accident Measures": No electrical equipment is allowed to operate without protection. The present invention proposes a relay protection technology solution for bypass breaker failure protection in a 220kV substation with double busbars and bypass busbar connection, which can adapt to the bypass line and bypass transformer operation modes. Summary of the Invention

[0005] The purpose of the present invention is to provide a relay protection method for bypass circuit breaker failure protection, so as to solve the technical problem that in a 220kV substation with double busbars and bypass busbars, it is impossible to implement bypass circuit breaker failure protection in the bypass line and bypass transformer operation mode.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A relay protection method for bypass circuit breaker failure protection, comprising:

[0008] 1. Selection of busbar protection circuit breaker branches

[0009] The busbar protection designed according to the six unified standards generally has 24 branches, including 1 busbar circuit breaker branch, 17 line circuit breaker branches, 4 transformer circuit breaker branches, and 2 branches as spare branches.

[0010] 1.1 Selection of busbar protection circuit breaker branches under bypass line mode

[0011] The busbar protection in the bypass line mode can adopt one of the 17 line circuit breaker branches to form the corresponding circuits of busbar protection and failure protection of the bypass circuit breaker in this mode.

[0012] 1.2 Selection of busbar protection circuit breaker branches under bypass transformer mode

[0013] Because busbar protection employs four transformer branches, current 220kV substations typically only have two or three transformers, using two or three 220kV transformer branches. The unused No. 3 or No. 4 transformer branch in the 220kV busbar protection can be used to form the busbar protection and failure protection circuits for the bypass circuit breaker in the transformer-replacing mode.

[0014] 2. Bypass circuit breaker failure protection configuration scheme

[0015] Circuit breaker failure protection generally consists of three parts: starting circuit, logic judgment and delay circuit and tripping output circuit.

[0016] 2.1 Access to the bypass disconnector position contacts

[0017] 2.1.1 Connection of bypass disconnector position contacts in bypass line mode

[0018] The position contacts 1G and 2G of the bypass disconnectors for bus sections I and II are connected to the 220kV busbar protection via the switching pressure plate QHLP2, forming a circuit for the bypass breaker branch current to participate in the current calculation circuit for bus section I or II protection. When the bypass breaker is operating in place of the line breaker, the auxiliary contact input 1G or 2G of the busbar disconnector for section I or II of the line breaker is connected to the bypass breaker branch (using the line branch) within the busbar protection device, transmitting information about the busbar on which the bypass breaker is operating to the busbar protection device, enabling busbar operation mode identification and calculation of the small differential current for bus sections I and II of the busbar differential protection.

[0019] 2.1.2 Connection of bypass disconnector position contacts in bypass transformer mode

[0020] The bypass disconnector position contacts 1G and 2G for busbar sections I and II are connected to the 220kV busbar protection via the QHLP2 switch, forming a loop for the bypass breaker branch current to participate in the current calculation for busbar section I or II protection. When the bypass breaker operates in transformer breaker replacement mode, the bypass current is connected to the vacant transformer branch No. 3 or No. 4 in the busbar protection. The inputs of the auxiliary contacts 1G and 2G, which reflect the busbar on which the bypass breaker is operating, must also be connected to the corresponding transformer branch in the busbar protection. This allows identification of the busbar operating mode and calculation of the small differential current for busbar sections I and II of the busbar differential protection.

[0021] 2.2 Solution for connecting bypass circuit breaker secondary current to busbar protection current loop

[0022] 2.2.1 Scheme of connecting the secondary current of the bypass circuit breaker to the busbar protection current loop under the bypass line mode

[0023] The bypass circuit breaker CT secondary current I A , IB , I C , I N The current branch of the bypass bay (line branch) in the 220kV busbar protection device is connected by switching the pressure plate QHLP1. On the one hand, it constitutes the current of the bypass circuit breaker in the busbar protection, which is used for differential protection to calculate the differential current; on the other hand, it completes the current conversion in the busbar protection and converts the secondary current I A , I B , I C , I N Converted into phase current I φ , negative sequence current I2 and zero sequence current 3I0 constitute the current discrimination circuit of bypass circuit breaker failure protection.

[0024] 2.2.2 Scheme of connecting the secondary current of the bypass circuit breaker to the busbar protection current loop in the bypass transformer mode

[0025] The bypass circuit breaker CT secondary current I A , I B , I C , I N By switching the pressure plate QHLP1 to access the current branch of the vacant No. 3 or No. 4 transformer in the 220kV busbar protection device, on the one hand, it constitutes the current of the bypass circuit breaker in the busbar protection, which is used for differential protection to calculate the differential current; on the other hand, it completes the current conversion in the busbar protection and converts the secondary current I A , I B , I C , I N Converted into phase current I φ , negative sequence current I2 and zero sequence current 3I0 constitute the current discrimination circuit of bypass circuit breaker failure protection.

[0026] 2.3 Digital input access busbar protection scheme

[0027] 2.3.1 Busbar protection scheme for inputs connected to bypass lines

[0028] In bypass mode, the inputs to the busbar protection bypass bay are: 1) auxiliary contacts 1G and 2G of the circuit breaker disconnector position; 2) the line protection single-phase tripping relay action contact output TJ A 、TJ B 、TJ C 3) The line protection three-phase tripping relay action contact opens STJ. When the bypass line is running, if a single-phase fault occurs on the line, the line protection single-phase tripping relay action contact opens TJ A 、TJ B 、TJ CThe single-phase tripping start failure logic in the busbar protection bypass interval is entered through the pressure plate 5LP; if a phase-to-phase short circuit fault such as a three-phase short circuit occurs in the line, the line protection three-phase tripping relay action contact opens STJ and enters the three-phase tripping start failure logic in the busbar protection bypass interval through the pressure plate 6LP.

[0029] 2.3.2 Busbar protection scheme using bypass transformer as input

[0030] The input quantities connected to the busbar protection are: the electrical quantity protection tripping relay action contacts of the No. 1 or No. 2 transformer tripping 220kV side, 1TJ1 and 1TJ2 are two pairs of action contacts of the No. 1 transformer electrical quantity protection output relay, 2TJ1 and 2TJ2 are two pairs of action contacts of the No. 2 transformer electrical quantity protection, among which 1TJ1 or 2TJ1 contact is used to release the re-pressure locking element of the busbar protection, 1TJ2 or 2TJ2 contact is used for the starting circuit of the failure judgment logic of the No. 3 or No. 4 transformer branch in the 220kV busbar protection; when the 220kV bypass circuit breaker replaces the No. 1 transformer circuit breaker, if the No. 1 transformer fails, If there is a fault, the protection of transformer No. 1 will operate and send out signal 1TJ2 through pressure plate 1LP to enter the busbar protection branch failure judgment logic of transformer No. 3 or transformer No. 4 that is unoccupied, and at the same time send out signal 1TJ1 through 3LP pressure plate to enter the busbar protection to release the re-pressure locking element; when the 220kV bypass circuit breaker replaces the 220kV circuit breaker of transformer No. 2 to operate, if transformer No. 2 fails, the protection of transformer No. 2 will operate and send out signal 2TJ2 through pressure plate 2LP to enter the busbar protection branch failure judgment logic of transformer No. 3 or transformer No. 4 that is unoccupied, and at the same time send out signal 2TJ1 through 4LP pressure plate to enter the busbar protection to release the re-pressure locking element.

[0031] 2.4 Start-up judgment circuit of bypass circuit breaker failure protection

[0032] The protection trip relay action contacts and current discrimination in 2.2 and 2.3 together constitute the start-up discrimination circuit of the bypass circuit breaker failure protection.

[0033] 2.5 Logical judgment and delay circuit of bypass circuit breaker failure protection

[0034] The logic judgment and delay circuit for bypass circuit breaker failure protection are completed by the internal logic of the busbar protection. In the bypass line mode, it is completed by the logic corresponding to the corresponding line branch; in the bypass transformer mode, it is completed by the logic corresponding to the corresponding transformer branch.

[0035] 2.6 Bypass circuit breaker failure protection tripping output scheme

[0036] The “six unified” protection regulations stipulate that busbar protection and circuit breaker failure protection share the same output circuit.

[0037] 2.6.1 Circuit breaker failure protection tripping output scheme under bypass line mode

[0038] Connect the output trip relay contacts of the bypass branch (using the line branch) in busbar protection in series with the throw-in / out pressure plate 1CLP to the trip circuit of the bypass circuit breaker protection panel to implement bypass circuit breaker failure protection. In bypass line operation mode (using the line branch), if the bypass circuit breaker fails, after failure detection, the busbar protection will trip the bus tie circuit breaker after a delay of t1 and all circuit breakers on the bus where the bypass circuit breaker is located after a delay of t2.

[0039] 2.6.2 Circuit breaker failure protection tripping output scheme under bypass transformer mode

[0040] 1) Connect the outlet trip relay contact of the vacant No. 3 or No. 4 transformer branch in the 220kV busbar protection in series with the throw-in / out pressure plate 5CLP to the trip circuit of the bypass circuit breaker protection panel to realize the failure protection tripping of the bypass circuit breaker; 2) Connect the failure output contact of the vacant No. 3 or No. 4 transformer branch in the 220kV busbar protection in series with the throw-in / out pressure plate 6CLP and the switching pressure plate 7CLP to the failure joint tripping input circuit of the No. 1 transformer protection panel. If any current among the phase current, negative sequence current and zero sequence current is greater than the set value, the No. 1 transformer protection main outlet will be started after a 50ms delay to realize the failure protection tripping of 1 The circuit breakers on each side of the No. 2 transformer are connected; or the failure-tripping contacts of the vacant No. 3 or No. 4 transformer branches in the 220kV busbar protection are connected in series with the throw-in / out pressure plate 6CLP and the switching pressure plate 8CLP to the failure inter-tripping circuit of the No. 2 transformer protection panel. If any of the phase current, negative sequence current and zero sequence current is greater than the set value, the total protection output of No. 2 transformer is started after a 50ms delay, and the failure protection trips the circuit breakers on each side of No. 2 transformer. When the bypass circuit breaker fails, the 220kV busbar protection will trip the bus tie circuit breaker after a delay of t1 after failure judgment, and will trip all circuit breakers on the bus where the bypass circuit breaker is located after a delay of t2.

[0041] The purpose of the present invention can be further achieved by the following technical measures:

[0042] The above-mentioned relay protection method for bypass circuit breaker failure protection,

[0043] The method for judging whether there is current in the bypass circuit breaker 2DL is to collect the secondary winding current I of the current transformer of the bypass circuit breaker 2DL respectively. A , I B , I C , I N , and converted into phase current I φ , negative sequence current I2 and zero sequence current 3I0, whether there is a fault current is determined by the phase current, negative sequence current and zero sequence current. The current setting principles are as follows:

[0044] 1) Setting of current setting value and time setting value of bypass circuit breaker in bypass line mode

[0045] Phase current setting value: Set the current value with sufficient sensitivity to the two-phase short-circuit fault at the end of the line under the minimum operating mode, with a sensitivity coefficient of ≥1.5;

[0046] Negative sequence current setting value: set with sufficient sensitivity for asymmetric short circuit fault at the end of the line under the minimum operating mode, with a sensitivity coefficient ≥ 2.0;

[0047] Zero-sequence current setting value: set with sufficient sensitivity to the minimum ground fault at the end of the line under the minimum operating mode, with a sensitivity coefficient ≥ 2.0;

[0048] The bypass circuit breaker failure protection method trips the 220kV bus tie breaker after determining that the bypass circuit breaker has failed, with a delay of t1 of 50 milliseconds; and trips all circuit breakers of the faulty busbar after a delay of t2 of 200 milliseconds.

[0049] 2) Setting of current setting value and time setting value of bypass circuit breaker in bypass transformer mode

[0050] Phase current setting value: Set the current value to ensure sufficient sensitivity to two-phase short-circuit faults under the minimum operating mode of the transformer low-voltage side, with a sensitivity coefficient of ≥1.5;

[0051] Negative sequence current setting value: It is set based on the sufficient sensitivity of the asymmetric short-circuit fault of the low-voltage side busbar of the transformer in the minimum operating mode, with a sensitivity coefficient of ≥2.0;

[0052] Zero-sequence current setting value: It is set with sufficient sensitivity to the minimum ground fault of the 110kV busbar on the transformer in the minimum operating mode, with a sensitivity coefficient of ≥2.0;

[0053] The above bypass circuit breaker failure protection method trips the 220kV bus tie circuit breaker after determining that the bypass circuit breaker has failed, with a delay of t1 being 50 milliseconds; and trips all circuit breakers of the faulty busbar after a delay of t2 being 200 milliseconds.

[0054] The above-mentioned relay protection method for bypass circuit breaker failure protection,

[0055] The calculation formula of negative sequence current I2 is: A2 =1 / 3(I A +α 2 I B +αI C ), I B2 =1 / 3(I B +α 2 I C +αI A ), I C2 =1 / 3(IC +α 2 I A +αI B );

[0056] The calculation formula of zero sequence current 3I0 is: 3I0=1 / 3(I A +I B +I C ).

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] 1. The present invention connects the 220kV bypass breaker CT secondary current and line protection output signal to the line branch in the six unified busbar protection to form the bypass breaker failure protection of the bypass breaker in the bypass line mode. By switching the pressure plate, the No. 1 and No. 2 transformer protection output signals and the bypass breaker CT secondary current can also be connected to the vacant transformer branch (No. 3 or No. 4 transformer branch) in the six unified busbar protection to form the bypass breaker failure protection of the bypass breaker in the bypass transformer mode. In the bypass line or transformer mode, the bypass breaker is prevented from operating without failure protection, and the fault can be quickly cut off to ensure the safe and stable operation of the power grid and improve the reliability of the power supply of the power grid.

[0059] 2. By switching the pressure plate, this bypass circuit breaker failure protection is applicable to bypass circuit breaker failure protection in various operating modes, such as the bypass circuit breaker replacing the line circuit breaker, the bypass circuit breaker empty-charging the 220kV bypass busbar, and bypassing the No. 1 or No. 2 transformer.

[0060] 3. The solution of the present invention is simple, practical, easy to implement, and utilizes existing protection devices. There is no need to reconfigure the protection devices, no increase in equipment investment, no additional costs, and good economic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 This is the primary main wiring diagram of transformer No. 1 or No. 2 in a 220kV substation;

[0062] Figure 2 This is a schematic diagram of bypass circuit breaker failure protection in bypass line or bypass transformer circuit breaker mode;

[0063] Figure 3 This is the schematic diagram of the bypass line circuit breaker failure protection trip output;

[0064] Figure 4 This is the schematic diagram of the tripping output of the bypass transformer circuit breaker failure protection;

[0065] Figure 5 This is the transformer failure tripping circuit diagram. DETAILED DESCRIPTION

[0066] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0067] like Figure 1 As shown, the power transmission and distribution network used in the present invention is a 220kV substation double busbar with bypass primary main connection system network. The 220kV system primary main connection of the power transmission and distribution network includes: 220kV busbar section I and busbar section II connected to the 220kV circuit breaker bay of transformer No. 1 or transformer No. 2, 220kV bypass circuit breaker bay and 220kV busbar section I and busbar section II voltage transformers (hereinafter referred to as PTs), the transformer 220kV circuit breaker bay is connected to the busbar side disconnector, 220kV side circuit breaker 1DL, current transformer 1LH, transformer side disconnector and bypass busbar side disconnector; 220kV line circuit breaker bay There are busbar side disconnectors, 220kV line circuit breakers 3DL, current transformers 3LH, and bypass busbar side disconnectors; the 220kV bypass circuit breaker bays are equipped with busbar side disconnectors, 220kV bypass circuit breaker 2DL, current transformers 2LH, and bypass busbar side disconnectors; the 220kV bypass circuit breaker bays are connected to 220kV bypass busbars; the 220kV bypass busbars are connected to transformer No. 1 or No. 2 through transformer bypass disconnectors No. 1 or No. 2, and are connected to the 220kV line through line bypass disconnectors.

[0068] When bypass breaker 2DL replaces line breaker 3DL, bypass breaker protection is enabled. However, when bypass breaker 2DL replaces transformer breaker 1DL, bypass breaker failure protection is disabled because it was not initially designed for this operation. This paper proposes a relay protection method for bypass breaker failure protection in 220kV substations with dual busbars and bypass busbars in transmission and distribution networks, where bypass breakers replace both line breakers and transformer breakers.

[0069] The control method includes the following control processes:

[0070] 1. Selection of busbar protection circuit breaker branches

[0071] The busbar protection designed according to the six unified standards generally has 24 branches, including 1 busbar circuit breaker branch, 17 line circuit breaker branches, 4 transformer circuit breaker branches, and 2 branches as spare branches.

[0072] 1.1 Selection of busbar protection circuit breaker branches under bypass line mode

[0073] The busbar protection in the bypass line mode can adopt one of the 17 line circuit breaker branches to form the corresponding circuits of busbar protection and failure protection of the bypass circuit breaker in this mode.

[0074] 1.2 Selection of busbar protection circuit breaker branches under bypass transformer mode

[0075] Because busbar protection employs four transformer branches, current 220kV substations typically only have two or three transformers, using two or three 220kV transformer branches. The unused No. 3 or No. 4 transformer branch in the 220kV busbar protection can be used to form the busbar protection and failure protection circuits for the bypass circuit breaker in the transformer-replacing mode.

[0076] 2. Bypass circuit breaker failure protection configuration scheme

[0077] Circuit breaker failure protection generally consists of three parts: starting circuit, logic judgment and delay circuit and tripping output circuit.

[0078] 2.1 Access to the bypass disconnector position contacts

[0079] 2.1.1 Connection of bypass disconnector position contacts in bypass line mode

[0080] The position contacts 1G and 2G of the bypass disconnectors for bus sections I and II are connected to the 220kV busbar protection via the switching pressure plate QHLP2, forming a circuit for the bypass breaker branch current to participate in the current calculation circuit for bus section I or II protection. When the bypass breaker is operating in place of the line breaker, the auxiliary contact input 1G or 2G of the busbar disconnector for section I or II of the line breaker is connected to the bypass breaker branch (using the line branch) within the busbar protection device, transmitting information about the busbar on which the bypass breaker is operating to the busbar protection device, enabling busbar operation mode identification and calculation of the small differential current for bus sections I and II of the busbar differential protection.

[0081] 2.1.2 Connection of bypass disconnector position contacts in bypass transformer mode

[0082] The bypass disconnector position contacts 1G and 2G for busbar sections I and II are connected to the 220kV busbar protection via the QHLP2 switch, forming a loop for the bypass breaker branch current to participate in the current calculation for busbar section I or II protection. When the bypass breaker operates in transformer breaker replacement mode, the bypass current is connected to the vacant transformer branch No. 3 or No. 4 in the busbar protection. The inputs of the auxiliary contacts 1G and 2G, which reflect the busbar on which the bypass breaker is operating, must also be connected to the corresponding transformer branch in the busbar protection. This allows identification of the busbar operating mode and calculation of the small differential current for busbar sections I and II of the busbar differential protection.

[0083] 2.2 Solution for connecting bypass circuit breaker secondary current to busbar protection current loop

[0084] 2.2.1 Scheme of connecting the secondary current of the bypass circuit breaker to the busbar protection current loop under the bypass line mode

[0085] The bypass circuit breaker CT secondary current I A , I B , I C , I N The current branch of the bypass bay (line branch) in the 220kV busbar protection device is connected by switching the pressure plate QHLP1. On the one hand, it constitutes the current of the bypass circuit breaker in the busbar protection, which is used for differential protection to calculate the differential current; on the other hand, it completes the current conversion in the busbar protection and converts the secondary current I A , I B , I C , I N Converted into phase current I φ , negative sequence current I2 and zero sequence current 3I0, constitute the current discrimination circuit of bypass circuit breaker failure protection. Figure 2 .

[0086] 2.2.2 Scheme of connecting the secondary current of the bypass circuit breaker to the busbar protection current loop in the bypass transformer mode

[0087] The bypass circuit breaker CT secondary current I A , I B , I C , I N By switching the pressure plate QHLP1 to access the current branch of the vacant No. 3 or No. 4 transformer in the 220kV busbar protection device, on the one hand, it constitutes the current of the bypass circuit breaker in the busbar protection, which is used for differential protection to calculate the differential current; on the other hand, it completes the current conversion in the busbar protection and converts the secondary current I A , I B , I C , I N Converted into phase current I φ , negative sequence current I2 and zero sequence current 3I0, constitute the current discrimination circuit of bypass circuit breaker failure protection. Figure 2 .

[0088] 2.3 Digital input access busbar protection scheme

[0089] 2.3.1 Busbar protection scheme for inputs connected to bypass lines

[0090] In bypass mode, the inputs to the busbar protection bypass bay are: 1) auxiliary contacts 1G and 2G of the circuit breaker disconnector position; 2) the line protection single-phase tripping relay action contact output TJ A 、TJ B 、TJ C3) The line protection three-phase tripping relay action contact opens STJ. When the bypass line is running, if a single-phase fault occurs on the line, the line protection single-phase tripping relay action contact opens TJ A 、TJ B 、TJ C The single-phase trip start failure logic in the busbar protection bypass compartment is entered through the pressure plate 5LP; if a phase-to-phase short circuit fault such as a three-phase short circuit occurs in the line, the line protection three-phase trip relay action contact opens STJ and enters the three-phase trip start failure logic in the busbar protection bypass compartment through the pressure plate 6LP. Figure 2 .

[0091] 2.3.2 Busbar protection scheme using bypass transformer as input

[0092] The inputs to the busbar protection are: the electrical quantity protection tripping relay contact when the No. 1 or No. 2 transformer trips the 220kV side, Figure 2 1TJ1 and 1TJ2 are two pairs of action contacts of the No. 1 transformer electrical quantity protection output relay, 2TJ1 and 2TJ2 are two pairs of action contacts of the No. 2 transformer electrical quantity protection, wherein 1TJ1 or 2TJ1 contact is used to release the re-pressure locking element of the busbar protection, 1TJ2 or 2TJ2 contact is used for the start circuit of the failure judgment logic of the No. 3 or No. 4 transformer branch in the 220kV busbar protection; when the 220kV bypass circuit breaker replaces the No. 1 transformer circuit breaker, if the No. 1 transformer fails, the No. 1 transformer protection action signal 1TJ2 is sent through The pressure plate 1LP enters the busbar protection vacant No. 3 transformer or No. 4 transformer branch failure judgment logic, and at the same time, the signal 1TJ1 is opened through the 3LP pressure plate to enter the busbar protection to release the re-pressure locking element; when the 220kV bypass circuit breaker replaces the No. 2 transformer 220kV circuit breaker, if the No. 2 transformer fails, the No. 2 transformer protection action opens the signal 2TJ2 through the pressure plate 2LP to enter the busbar protection vacant No. 3 transformer or No. 4 transformer branch failure judgment logic, and at the same time, the signal 2TJ1 is opened through the 4LP pressure plate to enter the busbar protection to release the re-pressure locking element. Detailed circuit see Figure 2 .

[0093] 2.4 Start-up judgment circuit of bypass circuit breaker failure protection

[0094] The protection trip relay action contacts and current discrimination in 2.2 and 2.3 together constitute the start-up discrimination circuit of the bypass circuit breaker failure protection.

[0095] 2.5 Logical judgment and delay circuit of bypass circuit breaker failure protection

[0096] The logic judgment and delay circuit for bypass circuit breaker failure protection are completed by the internal logic of the busbar protection. In the bypass line mode, it is completed by the logic corresponding to the corresponding line branch; in the bypass transformer mode, it is completed by the logic corresponding to the corresponding transformer branch.

[0097] 2.6 Bypass circuit breaker failure protection tripping output scheme

[0098] The “six unified” protection regulations stipulate that busbar protection and circuit breaker failure protection share the same output circuit.

[0099] 2.6.1 Circuit breaker failure protection tripping output scheme under bypass line mode

[0100] Connect the output trip relay contact of the bypass branch (using line branch) in busbar protection in series with the throw-in / out pressure plate 1CLP to the trip circuit of the bypass circuit breaker protection panel to realize bypass circuit breaker failure protection. In the bypass line operation mode (using line branch), when the bypass circuit breaker fails, after failure judgment, the busbar protection will trip the bus tie circuit breaker after t1 delay, and trip all circuit breakers on the bus where the bypass circuit breaker is located after t2 delay. Figure 3 .

[0101] 2.6.2 Circuit breaker failure protection tripping output scheme under bypass transformer mode

[0102] 1) Connect the trip relay contacts of the vacant No. 3 or No. 4 transformer branch in the 220kV busbar protection in series with the throw-in / out pressure plate 5CLP to the trip circuit of the bypass circuit breaker protection panel to achieve failure protection tripping of the bypass circuit breaker, see Figure 4 ; 2) The failure output contact of the vacant No. 3 or No. 4 transformer branch in the 220kV busbar protection is connected in series with the throw-in / out pressure plate 6CLP and the switching pressure plate 7CLP to the failure joint tripping circuit of the No. 1 transformer protection screen. After the current criterion (any current among the phase current, negative sequence current and zero sequence current is greater than the setting value), the No. 1 transformer protection main outlet is started after a 50ms delay to achieve failure protection tripping of the circuit breakers on each side of the No. 1 transformer; or the failure output contact of the vacant No. 3 or No. 4 transformer branch in the 220kV busbar protection is connected in series with the throw-in / out pressure plate 6CLP and the switching pressure plate 8CLP to the failure joint tripping circuit of the No. 2 transformer protection screen. After the current criterion (any current among the phase current, negative sequence current and zero sequence current is greater than the setting value), the No. 2 transformer protection main outlet is started after a 50ms delay to achieve failure protection tripping of the circuit breakers on each side of the No. 2 transformer, see Figure 4 When the bypass circuit breaker fails, after failure identification, the 220kV busbar protection will trip the bus tie circuit breaker after a delay of t1, and will trip all circuit breakers on the bus where the bypass circuit breaker is located after a delay of t2.

[0103] 3 Setting of current setting value and time setting value of bypass circuit breaker

[0104] In the above-mentioned relay protection method for bypass circuit breaker failure protection, the method for judging whether there is current in the bypass circuit breaker 2DL is to respectively collect the secondary winding current I of the current transformer of the bypass circuit breaker 2DL. A , I B , I C , I N , and converted into phase current I φ , negative sequence current I2 and zero sequence current 3I0, the phase current, negative sequence current and zero sequence current are used to determine whether there is a fault current. The setting principles of the above currents are as follows:

[0105] 3.1 Setting of current and time settings of bypass circuit breaker in bypass line mode

[0106] Phase current setting value: Set the current value with sufficient sensitivity to the two-phase short-circuit fault at the end of the line under the minimum operating mode, with a sensitivity coefficient of ≥1.5;

[0107] Negative sequence current setting value: set with sufficient sensitivity for asymmetric short circuit fault at the end of the line under the minimum operating mode, with a sensitivity coefficient ≥ 2.0;

[0108] Zero-sequence current constant setting: Set with sufficient sensitivity for the minimum ground fault at the end of the line under the minimum operating mode, with a sensitivity coefficient ≥ 2.0.

[0109] The above bypass circuit breaker failure protection method trips the 220kV bus tie circuit breaker after determining that the bypass circuit breaker has failed, with a delay of t1 being 50 milliseconds; and trips all circuit breakers of the faulty busbar after a delay of t2 being 200 milliseconds.

[0110] 3.2 Setting of current and time settings of bypass circuit breaker in bypass transformer mode

[0111] Phase current setting value: Set the current value to ensure sufficient sensitivity to two-phase short-circuit faults under the minimum operating mode of the transformer low-voltage side, with a sensitivity coefficient of ≥1.5;

[0112] Negative sequence current setting value: It is set based on the sufficient sensitivity of the asymmetric short-circuit fault of the low-voltage side busbar of the transformer in the minimum operating mode, with a sensitivity coefficient of ≥2.0;

[0113] Zero-sequence current setting value: It is set with sufficient sensitivity to the minimum grounding fault of the 110kV side busbar of the transformer in the minimum operating mode, and the sensitivity coefficient is ≥2.0.

[0114] The above bypass circuit breaker failure protection method trips the 220kV bus tie circuit breaker after determining that the bypass circuit breaker has failed, with a delay of t1 being 50 milliseconds; and trips all circuit breakers of the faulty busbar after a delay of t2 being 200 milliseconds.

[0115] 3.3 Calculation of each sequence current

[0116] The calculation formula of negative sequence current I2 is: A2 =1 / 3(I A +α 2 I B +αI C ), I B2 =1 / 3(I B +α 2 I C +αI A ), I C2 =1 / 3(I C +α 2 I A +αI B ).

[0117] The calculation formula of zero sequence current 3I0 is: 3I0=1 / 3(I A +I B +I C ).

[0118] This solution can also be used for bypass circuit breaker failure protection in bypass operation mode in substations with double busbars and bypass busbars at other voltage levels.

[0119] Provide the specific embodiment of the method of the present invention below:

[0120] 1.1 Implementation of bypass circuit breaker failure protection under bypass line mode

[0121] When bypass breaker 2DL replaces line breaker 3DL, bypass breaker 2DL operates, line breaker 3DL is in cold standby, and the bypass disconnector of line breaker 3DL operates. At this time, the line bay's own protection is disabled, the bypass breaker protection is enabled, and the setting must match the line it replaces. The 5LP and 6LP pressure plates are activated (using the corresponding circuits and logic of the line branches within the busbar protection). The secondary current of the bypass 2DL breaker CT is connected to the bypass branch of the busbar protection via the switching pressure plate QHLP1. In this operating mode, if a single-phase fault occurs on the line, the bypass breaker protection single-phase tripping action contact opens to "1". This signal passes through pressure plate 5LP and enters the bypass breaker failure logic in the busbar protection. If the judgment logic meets the conditions, the 220kV bus tie breaker will trip after a delay of t1, and all circuit breakers (including the bypass breaker) on the faulty bus will trip after a delay of t2. In addition, if a phase-to-phase fault such as a three-phase short circuit occurs in the line, the bypass circuit breaker protection three-phase tripping action will be turned on as "1". The signal will enter the bypass circuit breaker failure logic in the busbar protection through the 6LP pressure plate. If the judgment logic meets the conditions, the 220kV bus tie circuit breaker will be tripped after a t1 delay, and all circuit breakers (including bypass circuit breakers) of the faulty bus will be tripped after a t2 delay.

[0122] 1.2 Implementation of bypass circuit breaker failure protection in bypass mode for transformer No. 1

[0123] When bypass circuit breaker 2DL replaces transformer breaker 1DL for operation, bypass circuit breaker 2DL is in operation, transformer breaker 1DL is in cold standby, and transformer bypass disconnector 1 is in operation. 1LP and 3LP pressure plates are put into operation, and 2LP and 4LP pressure plates are withdrawn (using the corresponding circuit and logic of the transformer branch). The secondary current of bypass 2DL circuit breaker CT is connected to the vacant transformer branch 3 or 4 in the busbar protection through switching pressure plate QHLP1. Under this operating mode, if transformer No. 1 fails and bypass circuit breaker 2DL fails. Then the output signal 1TJ2 of transformer No. 1 protection enters the transformer No. 3 or 4 failure judgment logic in the busbar protection through pressure plate 1LP, and at the same time, the output signal 1TJ1 enters the busbar protection release re-pressure locking element through the 3LP pressure plate. In addition, since the fault does not disappear after the transformer No. 1 protection output relay is activated, there is current in the bypass circuit breaker branch, and the secondary current I A , I B , I C , I N Entering the No. 3 or No. 4 transformer branch in busbar protection, the phase current I φ The presence of current is determined by either negative-sequence current I2 or zero-sequence current 3I0. The No. 1 transformer protection output relay operates and outputs a signal, the bypass circuit breaker's presence criteria, and the "re-voltage element" form an "AND gate" relationship. When all of these conditions are met, the 220kV bus tie circuit breaker trips after a delay of t1, and all circuit breakers on the faulty busbar trip after a delay of t2.

[0124] 1.3 Implementation of bypass circuit breaker failure protection in bypass mode for No. 2 transformer

[0125] In the bypass-generated No. 2 transformer mode, the bypass circuit breaker failure protection is implemented in the same way as the bypass circuit breaker failure protection in the bypass-generated No. 1 transformer mode, and will not be repeated here.

[0126] 1.4 Implementation of Bypass Breaker Failure Protection in Bypass Breaker No-Charge 220kV Bypass Busbar Mode

[0127] When the bypass breaker 2DL is operating in the empty charging state of the 220kV bypass bus, the bypass breaker 2DL is in operation, the bypass breaker's own protection is enabled, the 5LP and 6LP pressure plates are put into operation (i.e., the corresponding circuits and logic of the line branches are used), and the 1LP, 2LP, 3LP and 4LP pressure plates are withdrawn. In this operating mode, if the 220kV bypass bus fails and the bypass breaker 2DL fails, the bypass breaker protection output signal enters the bypass breaker failure judgment logic in the bus protection through the pressure plate 5LP or 6LP. In addition, since the fault does not disappear after the bypass breaker protection is activated, there is current in the bypass breaker, and the bypass breaker CT secondary current I A , IB , I C , I N Enters the bypass circuit breaker failure judgment logic in the busbar protection and is converted into phase current I φ , negative-sequence current I2, and zero-sequence current 3I0. Since the fault point is located on the 220kV bypass busbar, the electrical distance is close, and the voltage-compounding element must meet the requirements. The bypass breaker protection action signal, the bypass breaker current determination criteria, and the "compound voltage element" form an "AND gate" relationship. When all these conditions are met, the 220kV bus tie breaker trips after a delay of t1, and all circuit breakers on the faulty busbar (including the bypass breaker) trip after a delay of t2.

[0128] In addition to the above embodiments, the present invention may also have other implementation methods. Any technical solutions formed by equivalent replacement or equivalent transformation fall within the protection scope required by the present invention.

Claims

1. A relay protection method for bypass circuit breaker failure protection, characterized in that: include: 1.1) Selection of busbar protection circuit breaker branches in bypass mode: In the bypass line mode, the busbar protection adopts one of the 17 line circuit breaker branches to form the corresponding circuit of busbar protection and failure protection of the bypass circuit breaker in this mode; 1.2) Selection of busbar protection circuit breaker branches in bypass transformer mode: The vacant No. 3 or No. 4 transformer branch in the 220kV busbar protection is used to form the busbar protection and failure protection circuits of the bypass circuit breaker in the bypass transformer mode; 2.1) Access to the bypass disconnector position contacts: 2.1.1) Connection of bypass disconnector position contacts in bypass line mode: The position contacts 1G of the busbar bypass disconnector for section I and 2G of the busbar bypass disconnector for section II are connected to the 220kV busbar protection via the switching pressure plate QHLP2, forming a bypass breaker branch current that participates in the current calculation loop for busbar protection for section I or II. When the bypass breaker is operating in line breaker replacement mode, the position contacts 1G of the busbar bypass disconnector for section I and 2G of the busbar bypass disconnector for section II of the line breaker are connected to the bypass breaker branch of the busbar protection device, transmitting information about the busbar on which the bypass breaker is operating to the busbar protection device, thereby enabling identification of the busbar operating mode and calculation of the small differential currents of busbar sections I and II of the busbar differential protection. 2.1.2) Connection of the bypass disconnector position contacts in bypass transformer mode: The position contacts 1G of the busbar bypass disconnector for section I and 2G of the busbar bypass disconnector for section II are connected to the 220kV busbar protection via the switching pressure plate QHLP2, forming a circuit for the bypass breaker branch current to participate in the current calculation of the busbar protection for section I or section II. When the bypass breaker is operating in the transformer breaker replacement mode, the bypass current is connected to the vacant No. 3 or No. 4 transformer branch in the busbar protection. The position contacts 1G of the busbar bypass disconnector for section I and 2G of the busbar bypass disconnector for section II, which reflect the busbar on which the bypass breaker is operating, are synchronously connected to the corresponding transformer branch in the busbar protection, thereby realizing busbar operation mode identification and calculation of the small differential current of busbar sections I and II of the busbar differential protection. 2.2) Solution for connecting the bypass circuit breaker secondary current to the busbar protection current loop: 2.2.1) Solution for connecting the secondary current of the bypass circuit breaker to the busbar protection current loop in bypass line mode: The bypass circuit breaker CT secondary current I A , I B , I C , I N By switching the pressure plate QHLP1 to access the current branch of the bypass interval in the 220kV busbar protection device, the current of the bypass circuit breaker in the busbar protection is formed for the differential protection to perform differential current calculation; and the current conversion is completed in the busbar protection to convert the secondary current I A , I B , I C , I N Converted into phase current I φ , the negative sequence current I2 and the zero sequence current 3I0 constitute the current discrimination circuit of the bypass circuit breaker failure protection; 2.2.2) Solution for connecting the secondary current of the bypass circuit breaker to the busbar protection current loop in the bypass transformer mode: The bypass circuit breaker CT secondary current I A , I B , I C , I N By switching the pressure plate QHLP1, the current branch of the vacant No. 3 or No. 4 transformer in the 220kV busbar protection device is connected to form the current of the bypass circuit breaker in the busbar protection, which is used for differential protection to calculate the differential current; and the current conversion is completed in the busbar protection to convert the secondary current I A , I B , I C , I N Converted into phase current I φ , the negative sequence current I2 and the zero sequence current 3I0 constitute the current discrimination circuit of the bypass circuit breaker failure protection; 2.3) Digital input access busbar protection scheme: 2.3.1) Busbar protection scheme for bypass line digital input: In bypass line mode, the inputs to the busbar protection bypass bay are: 1) busbar disconnector position contact 1G and busbar disconnector position contact 2G of each branch circuit breaker; 2) line protection single-phase tripping relay action contact output TJ A 、TJ B 、TJ C ; 3) The line protection three-phase tripping relay action contact opens STJ; Among them, when the bypass line is running, if a single-phase fault occurs in the line, the line protection single-phase tripping relay action contact opens TJ A 、TJ B 、TJ C The single-phase trip start failure logic in the busbar protection bypass bay is entered through pressure plate 5LP. If a phase-to-phase short circuit or three-phase short circuit fault occurs on the line, the line protection three-phase trip relay action contact opens STJ and enters the three-phase trip start failure logic in the busbar protection bypass bay through pressure plate 6LP. 2.3.2) Busbar protection scheme with digital input connected to bypass transformer: The input quantities connected to the busbar protection are: the electrical quantity protection tripping relay action contacts of the No. 1 or No. 2 transformer tripping 220kV side, 1TJ1 and 1TJ2 are two pairs of action contacts of the No. 1 transformer electrical quantity protection output relay, 2TJ1 and 2TJ2 are two pairs of action contacts of the No. 2 transformer electrical quantity protection, among which 1TJ1 or 2TJ1 contact is used to release the re-pressure locking element of the busbar protection, 1TJ2 or 2TJ2 contact is used for the starting circuit of the failure judgment logic of the No. 3 or No. 4 transformer branch in the 220kV busbar protection; when the 220kV bypass circuit breaker replaces the No. 1 transformer circuit breaker, if the No. 1 transformer fails, If the No. 1 transformer fails, the No. 1 transformer protection action will send out signal 1TJ2 through pressure plate 1LP to enter the busbar protection branch failure judgment logic of the vacant No. 3 transformer or No. 4 transformer, and at the same time send out signal 1TJ1 through 3LP pressure plate to enter the busbar protection release re-pressure locking element; when the 220kV bypass circuit breaker replaces the No. 2 transformer 220kV circuit breaker to operate, if the No. 2 transformer fails, the No. 2 transformer protection action will send out signal 2TJ2 through pressure plate 2LP to enter the busbar protection branch failure judgment logic of the vacant No. 3 transformer or No. 4 transformer, and at the same time send out signal 2TJ1 through 4LP pressure plate to enter the busbar protection release re-pressure locking element; 2.4) Start-up judgment circuit of bypass circuit breaker failure protection: The protection trip relay action contacts and current discrimination in 2.2) and 2.3) together constitute the startup discrimination circuit for bypass circuit breaker failure protection; 2.5) Logical judgment and delay circuit of bypass circuit breaker failure protection: The logic judgment and delay circuit of bypass circuit breaker failure protection are completed by the internal logic of busbar protection. In bypass line mode, it is completed by the logic corresponding to the corresponding line branch. In bypass transformer mode, it is completed by the logic corresponding to the corresponding transformer branch. 2.6) Bypass circuit breaker failure protection tripping output scheme: Busbar protection and circuit breaker failure protection share one output circuit; 2.6.1) Circuit breaker failure protection tripping output scheme under bypass line mode: The output trip relay contact of the bypass branch in the busbar protection is connected in series with the throw-in / out pressure plate 1CLP, and connected to the trip circuit of the bypass circuit breaker protection panel to realize bypass circuit breaker failure protection; in the bypass line operation mode, when the bypass circuit breaker fails, after failure judgment, the busbar protection will trip the bus tie circuit breaker after a t1 delay, and trip all circuit breakers on the bus where the bypass circuit breaker is located after a t2 delay; 2.6.2) Circuit breaker failure protection tripping output scheme under bypass transformer mode: 1) Connect the output trip relay contacts of the vacant No. 3 or No. 4 transformer branch in the 220kV busbar protection in series with the throw-in / out pressure plate 5CLP, and connect them to the trip circuit of the bypass circuit breaker protection panel to realize the failure protection tripping of the bypass circuit breaker; 2) Connect the failure output contacts of the vacant No. 3 or No. 4 transformer branch in the 220kV busbar protection in series with the throw-in / out pressure plate 6CLP and the switching pressure plate 7CLP, and connect them to the failure joint tripping input circuit of the No. 1 transformer protection panel. If any current among the phase current, negative sequence current and zero sequence current is greater than the set value, the No. 1 transformer protection main output will be started after a 50ms delay to realize the failure protection tripping of 1 The circuit breakers on each side of the No. 3 transformer; or the failure-tripping contact of the vacant No. 3 or No. 4 transformer branch in the 220kV busbar protection is connected in series with the throw-in / out pressure plate 6CLP and the switching pressure plate 8CLP, and connected to the failure inter-tripping circuit of the No. 2 transformer protection panel. If any of the phase current, negative sequence current and zero sequence current is greater than the set value, the No. 2 transformer protection main output will be started after a 50ms delay, and the failure protection will trip the circuit breakers on each side of the No. 2 transformer; when the bypass circuit breaker fails, the 220kV busbar protection will trip the bus tie circuit breaker after a delay of t1 after failure judgment, and will trip all circuit breakers on the bus where the bypass circuit breaker is located after a delay of t2.

2. A relay protection method for bypass circuit breaker failure protection according to claim 1, characterized in that: The method for judging whether there is current in the bypass circuit breaker 2DL is to collect the secondary winding current I of the current transformer of the bypass circuit breaker 2DL respectively. A , I B , I C , I N , and converted into phase current I φ , negative sequence current I2 and zero sequence current 3I0, whether there is a fault current is determined by the phase current, negative sequence current and zero sequence current. The current setting principles are as follows: 1) Setting of the current setting value and time setting value of the bypass circuit breaker in the bypass line mode: Phase current setting value: Set the current value with sufficient sensitivity to the two-phase short-circuit fault at the end of the line under the minimum operating mode, with a sensitivity coefficient of ≥1.5; Negative sequence current setting value: set with sufficient sensitivity for asymmetric short circuit fault at the end of the line under the minimum operating mode, with a sensitivity coefficient ≥ 2.0; Zero-sequence current setting value: set with sufficient sensitivity to the minimum ground fault at the end of the line under the minimum operating mode, with a sensitivity coefficient ≥ 2.0; The relay protection method for bypass circuit breaker failure protection is to trip the 220kV bus tie circuit breaker after the bypass circuit breaker failure is determined to have failed, after a delay of t1, t1 is 50 milliseconds; and to trip all circuit breakers of the faulty bus after a delay of t2, t2 is 200 milliseconds. 2) Setting of the current setting value and time setting value of the bypass circuit breaker in bypass transformer mode: Phase current setting value: Set the current value to ensure sufficient sensitivity to two-phase short-circuit faults under the minimum operating mode of the transformer low-voltage side, with a sensitivity coefficient of ≥1.5; Negative sequence current setting value: It is set based on the sufficient sensitivity of the asymmetric short-circuit fault of the low-voltage side busbar of the transformer in the minimum operating mode, with a sensitivity coefficient of ≥2.0; Zero-sequence current setting value: It is set with sufficient sensitivity to the minimum ground fault of the 110kV busbar on the transformer in the minimum operating mode, with a sensitivity coefficient of ≥2.0; The relay protection method for bypass circuit breaker failure protection is to trip the 220kV bus tie circuit breaker after determining that the bypass circuit breaker has failed, after a delay of t1, t1 is 50 milliseconds; and to trip all circuit breakers of the faulty bus after a delay of t2, t2 is 200 milliseconds.

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