Differential protection method and device for T zone fault, storage medium, and computer equipment

Abstract

The present application discloses a differential protection method and device for T-zone faults, a storage medium, and a computer device. The method comprises: calculating a differential current of a large differential mutation amount sampling value to determine whether there is a fault in the T-zone; if there is a fault, determining whether the differential current ratio braking of the large differential, the differential current mutation amount ratio braking of the small differential, and the differential current of the large differential all satisfy a preset T-zone protection action equation; if all satisfy, determining that the fault occurs in the entire T-zone, the busbar side circuit breaker is tripped to remove the fault, and determining whether there is current in the lead-out line on the line transformer side, if there is current in the lead-out line, removing the fault by remotely tripping the lead-out line circuit breaker on the line transformer side; if the differential current mutation amount ratio braking of the small differential does not satisfy the T-zone protection action equation corresponding to the differential current mutation amount ratio braking of the small differential, determining that the fault occurs in the dead zone of the lead-out line isolation switch, and removing the fault by remotely tripping the lead-out line circuit breaker on the line transformer side through overcurrent protection.

Description

Technical Field

[0001] The present application relates to the technical field of T-zone protection, and in particular to a differential protection method and device for T-zone faults, a storage medium, and a computer device. Background Art

[0002] For a semi-wired busbar system, the T zone refers to the short lead wires and external lead wires connected between the side circuit breaker and the middle circuit breaker. Lines, transformers, generators and other units are connected to the busbar system through the T zone. The T zone protection specifically refers to the relay protection function of this part.

[0003] At present, the existing T-zone protection generally includes ratio differential protection and two-stage outgoing line overcurrent protection, which mainly distinguishes the operating status of the T-zone and the protection function according to the status of the line or transformer disconnector, thereby completing the fault removal of the T-zone and the lead-out line.

[0004] The existing T-zone protection functions include three-side current differential protection, two-side current differential protection and overcurrent protection. T-zone protection uses auxiliary contacts of line or transformer isolation switches to control the conversion between three-difference protection and two-difference protection. Figure 1 As shown in the figure, when the line or transformer disconnector is closed (no input in "disconnector position TWJ"), the T zone protection adopts a three-side ratio braking current differential mode. When a fault occurs in the T zone, the protection trips two circuit breakers DL (side circuit breaker and middle circuit breaker) and transmits the signal to the opposite side remotely. When the line or transformer disconnector is opened (there is input in "disconnector position TWJ"), it is a two-side ratio braking current differential protection mode. At the same time, the two-stage overcurrent protection on the line side is opened as line end protection. When a fault occurs in the T zone, the current differential protection on both sides trips two circuit breakers DL (side circuit breaker and middle circuit breaker). When the two-stage overcurrent protection is activated, a remote trip signal is sent to the opposite side.

[0005] The three-side ratio differential protection is composed of three phases A, B, and C. If any differential current meets the following conditions, the three-side differential protection will be activated, and the action equation is:

[0006] |I1+I2+I3|>I CDDZ

[0007] |I1+I2+I3|>K*(|I1|+|I2|+|I3|) / 2

[0008] Where I1, I2, and I3 are the currents of the two circuit breakers and the lead-out CT respectively, K is the ratio braking coefficient, differential current = |I1+I2+I3|, braking current = (|I1|+|I2|+|I3|) / 2, I CDDZ is the differential action current setting.

[0009] The three-side ratio differential protection action curve is as follows: Figure 2 shown.

[0010] The three-side differential protection is activated to trip the two circuit breakers on this side, and the protection is transmitted to the opposite side to trip the circuit breaker related to the line.

[0011] The ratio differential protection on both sides is composed of three phases A, B, and C. If any differential current meets the following conditions, the differential protection on both sides will be activated, and the action equation is:

[0012] |I1+I2|>I CDDZ

[0013] |I1+I2|>K*(|I1|+|I2|) / 2

[0014] Where I1 and I2 are the CT currents of the two circuit breakers respectively, K is the ratio braking coefficient, differential current = |I1+I2|, braking current = (|I1|+|I2|) / 2, I CDDZ is the differential action current setting.

[0015] The action curve of the ratio differential protection on both sides is as follows: Figure 3 shown.

[0016] After the differential protection on both sides is activated, only the two circuit breakers on this side will trip.

[0017] When the line or transformer disconnector is open, the overcurrent protection function is activated. The overcurrent protection has two stages.

[0018] The action equation is:

[0019] I GL >I GLDZn

[0020] |I1+I2+I3|>0.9×I GLDZn

[0021] In the formula, I GL is the current of any phase of the lead-out CT, I GLDZn It is the current setting value of overcurrent protection stage I or stage II, n is I or II, I1, I2, I3 are the currents of two circuit breakers and lead-out line CT respectively, and they are composed of three phases A, B, C respectively.

[0022] If the current of any phase meets the above conditions, the overcurrent stage I or stage II will be output according to their respective setting time.

[0023] When the overcurrent protection is activated, a remote trip signal is sent to the opposite side, tripping the circuit breaker on the opposite side related to the line.

[0024] In summary, the existing differential protection schemes are heavily dependent on the position of the isolation switch. Once the position of the isolation switch is abnormal, the two-side or three-side differential function of the differential protection cannot be correctly put into operation, and the tripping behavior of the protection cannot be guaranteed, which may cause multiple tripping circuit breakers or mis-cutting of loads. Summary of the invention

[0025] In view of this, the present application provides a differential protection method and device, storage medium, and computer equipment for T-zone faults. The main purpose is to solve the problem that the existing differential protection scheme is heavily dependent on the position of the isolation switch. Once the position of the isolation switch is abnormal, the two-side or three-side differential function of the differential protection cannot be correctly put into use, and the tripping behavior of the protection cannot be guaranteed, which may cause multiple tripping circuit breakers or mis-cutting of loads.

[0026] According to one aspect of the present application, a differential protection method for a T-zone fault is provided, the method comprising:

[0027] Calculate the large-difference mutation amount sampling value differential current, and determine whether there is a fault in the T zone based on the mutation amount sampling value differential current;

[0028] If there is a fault, it is determined whether the differential current ratio braking of the large difference, the differential current mutation ratio braking of the small difference and the differential current of the large difference all meet the preset T-zone protection action equation;

[0029] If all conditions are met, it is determined that the fault occurs in the entire T zone, the busbar side circuit breaker is tripped to remove the fault, and the preset lead-out line current discrimination equation is used to determine whether there is current in the lead-out line on the line transformer side. If there is current in the lead-out line, the fault is removed by remotely tripping the lead-out line circuit breaker on the line transformer side;

[0030] If the ratio braking of the differential current mutation of the small difference does not satisfy the T zone protection action equation corresponding to the ratio braking of the differential current mutation of the small difference, it is determined that the fault occurs in the dead zone of the lead-out line isolation switch, and the fault is cut off by remotely tripping the lead-out line circuit breaker on the transformer side of the overcurrent protection.

[0031] Optionally, the calculation formula of the mutation amount sampling value differential current is as follows:

[0032] Δ(I1+I2+I3)=||(I1+I2+I3) K -(I1+I2+I3) K-T |-|(I1+I2+I3) K-T -(I1+I2+I3) K-2T ||

[0033] Among them, I1 represents the circuit breaker current on the bus side, I2 represents the circuit breaker current on the bus side, I3 represents the lead-out line current on the line transformer side, K represents the current time, KT represents the time one week ago, K-2T represents the time two weeks ago, and T represents the number of sampling points per week.

[0034] Optionally, judging whether there is a fault in the T zone based on the differential current of the mutation amount sampling value includes:

[0035] It is determined whether the differential current of the sudden change sampling value satisfies a preset fault determination equation. If so, it is determined that there is a fault in the T zone, wherein the fault determination equation is as follows:

[0036] Δ(I1+I2+I3)>I d0

[0037] Among them, Δ(I1+I2+I3) represents the differential current of the sudden change sampling value, I d0 Indicates the differential current threshold value.

[0038] Optionally, if there is a fault, judging whether the differential current ratio braking of the large difference, the differential current mutation ratio braking of the small difference, and the differential current of the large difference all satisfy a preset T-zone protection action equation includes:

[0039] Calculate the differential current of large difference, the braking current of large difference, the differential current mutation of small difference, the braking current mutation of small difference respectively, and set the braking coefficient;

[0040] Based on the differential current of the large difference, the braking current of the large difference, the differential current mutation of the small difference, the braking current mutation of the small difference and the braking coefficient, it is determined whether the differential current ratio braking of the large difference, the differential current mutation ratio braking of the small difference and the differential current of the large difference all satisfy the T-zone protection action equation, wherein the T-zone protection action equation corresponding to the differential current ratio braking of the large difference is as follows:

[0041] I dd >K*I fd

[0042] The T-zone protection action equation corresponding to the small differential current sudden change ratio braking is as follows:

[0043] ΔI dx >K*ΔI fx

[0044] The T-zone protection action equation corresponding to the large differential current is as follows:

[0045] I dd >I d0

[0046] Among them, I dd Indicates the large differential current, K indicates the braking coefficient, I fd Indicates the braking current of large difference, ΔI dx Indicates the differential current mutation amount of small difference, ΔI fx Indicates the sudden change in braking current for a small difference.

[0047] Optionally, the calculation formula of the large differential current is as follows:

[0048] I dd =|I1+I2+I3|

[0049] The calculation formula of the large difference braking current is as follows:

[0050] I fd =|I1|+|I2|+|I3|

[0051] The calculation formula of the small difference differential current mutation is as follows:

[0052] ΔI dx =|I dx -I dx-T |

[0053] Among them, I dx The differential current, I, represents the small difference in the current cycle dx-T A differential current representing a small difference from the previous cycle;

[0054] The calculation formula of the sudden change of braking current of the small difference is as follows:

[0055] ΔI fx =|I fx -I fx-T |

[0056] Among them, I fx Indicates the braking current of the small difference in the current cycle, I fx-T Indicates the braking current of the small difference from the previous cycle.

[0057] Optionally, the calculation formula of the small difference differential current is as follows:

[0058] I dx =|I1+I2|

[0059] The calculation formula of the braking current of the small difference is as follows:

[0060] I fx =|I1|+|I2|

[0061] Optionally, the lead-out line flow discriminant equation is as follows:

[0062] max{I3A ,I 3B ,I 3C}>I minset

[0063] Among them, I 3A Indicates the A-phase current of the lead wire on the line transformer side, I 3B Indicates the phase B current of the lead wire on the line transformer side, I 3C Indicates the phase C current of the lead wire on the line transformer side, I minset Indicates the current determination value.

[0064] According to another aspect of the present application, a differential protection device for a T-zone fault is provided, the device comprising:

[0065] A calculation module, used for calculating a large-difference mutation amount sampling value differential current, and judging whether there is a fault in the T zone based on the mutation amount sampling value differential current;

[0066] A judgment module, used for judging whether the differential current ratio braking of the large difference, the differential current mutation ratio braking of the small difference and the differential current of the large difference all satisfy the preset T zone protection action equation if a fault exists;

[0067] A removal module is used to determine that the fault occurs in the entire T zone if all conditions are met, and the busbar side circuit breaker is tripped to remove the fault, and to determine whether there is current on the lead-out line on the line transformer side through a preset lead-out line current discrimination equation. If there is current on the lead-out line, the fault is removed by remotely tripping the lead-out line circuit breaker on the line transformer side;

[0068] The remote trip module is used to determine that the fault occurs in the dead zone of the lead-out line isolation switch if the ratio braking of the differential current mutation amount of the small difference does not satisfy the T-zone protection action equation corresponding to the ratio braking of the differential current mutation amount of the small difference, and then cut off the fault by remotely tripping the lead-out line circuit breaker on the transformer side of the line through overcurrent protection.

[0069] Optionally, the calculation formula of the mutation amount sampling value differential current is as follows:

[0070] Δ(I1+I2+I3)=||(I1+I2+I3) K -(I1+I2+I3) K-T |-|(I1+I2+I3) K-T -(I1+I2+I3) K-2T ||

[0071] Among them, I1 represents the circuit breaker current on the bus side, I2 represents the circuit breaker current on the bus side, I3 represents the lead-out line current on the line transformer side, K represents the current time, KT represents the time one week ago, K-2T represents the time two weeks ago, and T represents the number of sampling points per week.

[0072] Optionally, the computing module is further used for:

[0073] It is determined whether the differential current of the sudden change sampling value satisfies a preset fault determination equation. If so, it is determined that there is a fault in the T zone, wherein the fault determination equation is as follows:

[0074] Δ(I1+I2+I3)>I d0

[0075] Among them, Δ(I1+I2+I3) represents the differential current of the sudden change sampling value, I d0 Indicates the differential current threshold value.

[0076] Optionally, the judging module is further configured to:

[0077] Calculate the differential current of large difference, the braking current of large difference, the differential current mutation of small difference, the braking current mutation of small difference respectively, and set the braking coefficient;

[0078] Based on the differential current of the large difference, the braking current of the large difference, the differential current mutation of the small difference, the braking current mutation of the small difference and the braking coefficient, it is determined whether the differential current ratio braking of the large difference, the differential current mutation ratio braking of the small difference and the differential current of the large difference all satisfy the T-zone protection action equation, wherein the T-zone protection action equation corresponding to the differential current ratio braking of the large difference is as follows:

[0079] I dd >K*I fd

[0080] The T-zone protection action equation corresponding to the small differential current sudden change ratio braking is as follows:

[0081] ΔI dx >K*ΔI fx

[0082] The T-zone protection action equation corresponding to the large differential current is as follows:

[0083] I dd >I d0

[0084] Among them, I dd Indicates the large differential current, K indicates the braking coefficient, I fd Indicates the braking current of large difference, ΔI dx Indicates the differential current mutation amount of small difference, ΔI fx Indicates the sudden change in braking current for a small difference.

[0085] Optionally, the calculation formula of the large differential current is as follows:

[0086] I dd =|I1+I2+I3|

[0087] The calculation formula of the large difference braking current is as follows:

[0088] I fd =|I1|+|I2|+|I3|

[0089] The calculation formula of the small difference differential current mutation is as follows:

[0090] ΔI dx =|I dx -U dx-T |

[0091] Among them, I dx The differential current, I, represents the small difference in the current cycle dx-T A differential current representing a small difference from the previous cycle;

[0092] The calculation formula of the sudden change of braking current of the small difference is as follows:

[0093] ΔI fx =|I fx -I fx-T |

[0094] Among them, I fx Indicates the braking current of the small difference in the current cycle, I fx-T Indicates the braking current of the small difference from the previous cycle.

[0095] Optionally, the calculation formula of the small difference differential current is as follows:

[0096] I dx =|I1+I2|

[0097] The calculation formula of the braking current of the small difference is as follows:

[0098] I fx =|I1|+|I2|

[0099] Optionally, the lead-out line flow discriminant equation is as follows:

[0100] max{I 3A ,I 3B ,I 3C}>I minset

[0101] Among them, I 3A Indicates the A-phase current of the lead wire on the line transformer side, I 3B Indicates the phase B current of the lead wire on the line transformer side, I3C Indicates the phase C current of the lead wire on the line transformer side, I minset Indicates the current determination value.

[0102] According to another aspect of the present application, a storage medium is provided, on which a computer program is stored, and when the program is executed by a processor, the differential protection method for T zone faults is implemented.

[0103] According to another aspect of the present application, a computer device is provided, including a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, wherein the processor implements the above-mentioned differential protection method for T zone faults when executing the program.

[0104] By means of the above technical scheme, the present application provides a differential protection method and device for T-zone faults, a storage medium, and a computer device. First, the differential current of the sudden change amount sampling value of the large difference is calculated, and whether there is a fault in the T zone is determined based on the differential current of the sudden change amount sampling value; then, if there is a fault, it is determined whether the differential current ratio braking of the large difference, the differential current sudden change amount ratio braking of the small difference, and the differential current of the large difference all satisfy the preset T-zone protection action equation; finally, if all are satisfied, it is determined that the fault occurs in the entire T zone, the bus side circuit breaker is tripped to remove the fault, and through the preset lead-out line current discrimination equation, it is determined whether there is flow in the lead-out line on the line transformer side, if there is flow in the lead-out line, the fault is removed by remotely tripping the lead-out line circuit breaker on the line transformer side; if the differential current sudden change amount ratio braking of the small difference does not satisfy the T-zone protection action equation corresponding to the differential current sudden change amount ratio braking of the small difference, it is determined that the fault occurs in the dead zone of the lead-out line isolation switch, and the fault is removed by remotely tripping the lead-out line circuit breaker on the line transformer side through overcurrent protection. The present application determines whether there is a fault in the T zone based on the differential current of the large difference mutation amount sampling value. If there is a fault, the fault occurs in the entire T zone or the dead zone of the lead-out line isolation switch based on the ratio braking of the small difference differential current mutation amount. If the fault occurs in the entire T zone, the busbar side circuit breaker will trip to cut off the fault, and by judging whether there is a current difference on the lead-out line on the line transformer side, it is determined whether the lead-out line circuit breaker will be remotely tripped to cut off the fault. If the fault occurs in the dead zone of the lead-out line isolation switch, the lead-out line circuit breaker will be remotely tripped through overcurrent protection to cut off the fault. In the present application, all judgments are made through electrical quantities, and there is no need for isolation switch verification and coordination. Therefore, it avoids the existing differential protection scheme from being heavily dependent on the isolation switch position. Once the isolation switch position is abnormal, the two-side or three-side differential function of the differential protection cannot be correctly put into use, and the tripping behavior of the protection cannot be guaranteed, which may cause problems such as multiple trip circuit breakers or mis-cut loads. The reliability and safety of T zone protection are improved.

[0105] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0106] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0107] Figure 1 It shows the protection function diagram provided by the background technology of this application;

[0108] Figure 2 The figure shows a three-side ratio differential protection action curve diagram provided by the background technology of the present application;

[0109] Figure 3 The figure shows a two-side ratio differential protection action curve diagram provided by the background technology of the present application;

[0110] Figure 4 A schematic flow chart of a differential protection method for a T-zone fault provided in an embodiment of the present application is shown;

[0111] Figure 5 The differential principle block diagram provided by the embodiment of the present application is shown;

[0112] Figure 6 A schematic flow chart of another differential protection method for a T-zone fault provided in an embodiment of the present application is shown;

[0113] Figure 7 A schematic diagram of the T-zone wiring form provided in an embodiment of the present application is shown;

[0114] Figure 8 A schematic structural diagram of a differential protection device for a T-zone fault provided in an embodiment of the present application is shown;

[0115] Fig. 9 A schematic diagram of the device structure of a computer device provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0116] The present application will be described in detail below with reference to the accompanying drawings and in combination with embodiments. It should be noted that the embodiments and features in the embodiments of the present application can be combined with each other without conflict.

[0117] In this embodiment, a differential protection method for T zone fault is provided, such as Figure 4 As shown, the method includes:

[0118] Step 101, calculating a large-difference mutation amount sampling value differential current, and judging whether there is a fault in the T zone based on the mutation amount sampling value differential current.

[0119] Step 102, if there is a fault, determine whether the differential current ratio braking of the large difference, the differential current sudden change ratio braking of the small difference and the differential current of the large difference all meet the preset T-zone protection action equation.

[0120] Step 103, if all conditions are met, it is determined that the fault occurs in the entire T zone, the bus side circuit breaker is tripped to cut off the fault, and a preset lead-out line current discrimination equation is used to determine whether there is current in the lead-out line on the line transformer side. If there is current in the lead-out line, the fault is cut off by remotely tripping the lead-out line circuit breaker on the line transformer side.

[0121] Step 104, if the differential current mutation ratio braking of the small difference does not satisfy the T zone protection action equation corresponding to the differential current mutation ratio braking of the small difference, it is determined that the fault occurs in the dead zone of the lead-out line isolation switch, and the fault is removed by remotely tripping the lead-out line circuit breaker on the transformer side of the overcurrent protection.

[0122] The differential protection method for T-zone fault provided in the embodiment of the present application first calculates the large difference sudden change amount sampling value differential current, and judges whether there is a fault in the T zone based on the large difference sudden change amount sampling value differential current. Then, if there is a fault in the T zone, such as Figure 5 As shown, it is determined whether the differential current ratio braking of large difference, the differential current mutation ratio braking of small difference and the differential current of large difference all meet the preset T zone protection action equation. Finally, if the differential current ratio braking of large difference, the differential current mutation ratio braking of small difference and the differential current of large difference all meet their corresponding T zone protection action equations, it is determined that the fault occurs in the entire T zone. At this time, the lead-out line isolation switch is in a closed state, the differential current ratio braking protection of large difference and the differential current mutation ratio braking of small difference act at the same time, the busbar side circuit breaker trips to cut off the fault, and through the preset lead-out line current discrimination equation, it is determined whether there is current on the lead-out line on the line transformer side. If there is current on the lead-out line on the line transformer side, the fault is cut off by remote tripping the lead-out line circuit breaker on the line transformer side. After judging whether the differential current ratio braking of large difference, the differential current mutation ratio braking of small difference and the differential current of large difference all satisfy the preset T zone protection action equation, if the differential current mutation ratio braking of small difference does not satisfy the T zone protection action equation corresponding to the differential current mutation ratio braking of small difference, then it is determined that the fault occurs in the dead zone of the lead-out line isolation switch. At this time, the lead-out line isolation switch is in the separated state, the differential current mutation ratio braking protection of small difference does not operate, and the fault is cut off by the overcurrent protection remote tripping line transformer side lead-out line circuit breaker.

[0123] By applying the technical solution of this embodiment, it is determined whether there is a fault in the T zone based on the differential current of the large difference mutation amount sampling value. If there is a fault, the fault occurs in the entire T zone or the dead zone of the lead-out line isolation switch based on the ratio braking of the small difference differential current mutation amount. If the fault occurs in the entire T zone, the busbar side circuit breaker will trip to cut off the fault, and by judging whether there is a current difference on the lead-out line on the line transformer side, it is determined whether the lead-out line circuit breaker will be remotely tripped to cut off the fault. If the fault occurs in the dead zone of the lead-out line isolation switch, the lead-out line circuit breaker will be remotely tripped through overcurrent protection to cut off the fault. In the present application, all judgments are made through electrical quantities, and there is no need for isolation switch verification and coordination. Therefore, it avoids the existing differential protection scheme from being heavily dependent on the isolation switch position. Once the isolation switch position is abnormal, the two-side or three-side differential function of the differential protection cannot be correctly put into operation, and the tripping behavior of the protection cannot be guaranteed, which may cause problems such as multiple trip circuit breakers or mis-cut loads. The reliability and safety of T zone protection are improved.

[0124] Further, as a refinement and extension of the specific implementation of the above embodiment, in order to fully illustrate the specific implementation process of this embodiment, another differential protection method for T zone fault is provided, such as Figure 6 As shown, the method includes:

[0125] Step 201 : Calculate the large-difference sudden change sampling value differential current, and determine whether there is a fault in the T zone based on the sudden change sampling value differential current.

[0126] Optionally, the calculation formula of the mutation amount sampling value differential current included in step 201 is as follows:

[0127] Δ(I1+I2+I3)=||(I1+I2+I3) K -(I1+I2+I3) K-T |-|(I1+I2+I3) K-T -(I1+I2+I3) K-2T ||

[0128] Among them, I1 represents the circuit breaker current on the bus side, I2 represents the circuit breaker current on the bus side, I3 represents the lead-out line current on the line transformer side, K represents the current time, KT represents the time one week ago, K-2T represents the time two weeks ago, and T represents the number of sampling points per week.

[0129] Optionally, in step 201, judging whether there is a fault in the T zone based on the mutation amount sampling value differential current further includes: judging whether the mutation amount sampling value differential current satisfies a preset fault judgment equation, and if so, judging that there is a fault in the T zone, wherein the fault judgment equation is as follows:

[0130] Δ(I1+I2+I3)>I d0

[0131] Among them, Δ(I1+I2+I3) represents the differential current of the sudden change sampling value, I d0 Indicates the differential current threshold value.

[0132] In this embodiment, according to Figure 7 The wiring form of the T zone shown is that the differential current with large difference is fixedly connected to the current of the side circuit breaker CT1, the current of the middle circuit breaker CT2, and the current of the lead-out line CT3, the differential current with small difference is fixedly connected to the current of the side circuit breaker CT1 and the current of the circuit breaker CT2, and the overcurrent protection is fixedly connected to the current of the lead-out line CT3. First, according to the differential current calculation formula of the large difference sudden change sampling value, the differential current of the large difference sudden change sampling value is calculated, and it is judged whether the differential current of the large difference sudden change sampling value satisfies the preset fault judgment equation. If it satisfies, it is judged that there is a fault in the T zone, otherwise, there is no fault in the T zone. Among them, the differential current threshold value in the fault judgment equation is generally taken as 0.2~10In, where In is the rated current of 5A or 1A.

[0133] Step 202, respectively calculate the differential current of the large difference, the braking current of the large difference, the differential current mutation amount of the small difference, and the braking current mutation amount of the small difference, and set the braking coefficient.

[0134] Optionally, the calculation formula of the large differential current included in step 202 is as follows:

[0135] I dd =|I1+I2+I3|

[0136] The calculation formula of the large difference braking current is as follows:

[0137] I fd =|I1|+|I2|+|I3|

[0138] The calculation formula of the small difference differential current mutation is as follows:

[0139] ΔI dx =|I dx -I dx-T |

[0140] Among them, I dx The differential current, I, represents the small difference in the current cycle dx-T Indicates the braking current of the small difference from the previous cycle.

[0141] The calculation formula of the sudden change of braking current of the small difference is as follows:

[0142] ΔI fx =|I fx -I fx-T |

[0143] Among them, Ifx Indicates the braking current of the small difference in the current cycle, I fx-T Indicates the braking current of the small difference from the previous cycle.

[0144] Optionally, step 202 further includes a calculation formula for the small differential current as follows:

[0145] I dx =|I1+I2|

[0146] The calculation formula of the braking current of the small difference is as follows:

[0147] I fx =|I1|+|I2|

[0148] Next, after determining that there is a fault in the T zone, the differential current of the large difference is calculated according to the differential current calculation formula of the large difference, the braking current of the large difference is calculated according to the braking current calculation formula of the large difference, the differential current mutation amount of the small difference is calculated according to the differential current mutation amount calculation formula of the small difference, and the braking current mutation amount of the small difference is calculated according to the braking current mutation amount calculation formula of the small difference, and the braking coefficient is set, where the braking coefficient is generally 0.3~0.8.

[0149] Among them, under normal operating conditions, if the lead-out line isolation switch is closed, the differential current with a small difference does not connect to the entire current, so it is an incomplete differential current. Therefore, the differential current with a small difference and the braking current use current mutation amounts, which can eliminate the impact of the differential current under normal operating conditions and improve the sensitivity of the protection.

[0150] Before calculating the sudden change amount of braking current of small difference and the sudden change amount of braking current of small difference, it also includes calculating the differential current of small difference according to the calculation formula of differential current of small difference, and calculating the braking current of small difference according to the calculation formula of braking current of small difference.

[0151] Step 203, based on the differential current of the large difference, the braking current of the large difference, the differential current mutation of the small difference, the braking current mutation of the small difference and the braking coefficient, determine whether the differential current ratio braking of the large difference, the differential current mutation ratio braking of the small difference and the differential current of the large difference all satisfy the T-zone protection action equation.

[0152] Optionally, the T-zone protection action equation corresponding to the large-difference differential current ratio braking included in step 203 is as follows:

[0153] I dd >K*I fd

[0154] The T-zone protection action equation corresponding to the small differential current sudden change ratio braking is as follows:

[0155] ΔI dx >K*ΔI fx

[0156] The T-zone protection action equation corresponding to the large differential current is as follows:

[0157] I dd >I d0

[0158] Among them, I dd Indicates the large differential current, K indicates the braking coefficient, I fd Indicates the braking current of large difference, ΔI dx Indicates the differential current mutation amount of small difference, ΔI fx Indicates the sudden change in braking current for a small difference.

[0159] Step 204, if all conditions are met, it is determined that the fault occurs in the entire T zone, the bus side circuit breaker is tripped to cut off the fault, and a preset lead-out line current discrimination equation is used to determine whether there is current in the lead-out line on the line transformer side. If there is current in the lead-out line, the fault is cut off by remotely tripping the lead-out line circuit breaker on the line transformer side.

[0160] Optionally, the lead-out line flow discrimination equation included in step 204 is as follows:

[0161] max{I 3A ,I 3B ,I 3C}>I minset

[0162] Among them, I 3A Indicates the A-phase current of the lead wire on the line transformer side, I 3B Indicates the phase B current of the lead wire on the line transformer side, I 3C Indicates the phase C current of the lead wire on the line transformer side, I minset Indicates the current determination value.

[0163] Next, based on the large differential current, large differential braking current, small differential current mutation, small differential braking current mutation and braking coefficient, it is determined whether the large differential current ratio braking, small differential current mutation ratio braking and large differential current meet the corresponding T zone protection action equations. If all are satisfied, it is determined that the fault in the T zone occurs in the entire T zone. At this time, the lead-out line isolation switch is in a closed state, and the large differential current ratio braking protection and the small differential current mutation ratio braking protection are simultaneously operated. The bus side circuit breaker, that is, the side circuit breaker and the middle circuit breaker are tripped to remove the fault, and the preset lead-out line current discrimination equation is used to determine whether the lead-out line on the line transformer side has current. If the lead-out line on the line transformer side has current, the fault is removed by remote tripping the lead-out line circuit breaker on the line transformer side. If there is no current on the lead-out line on the line transformer side, no remote tripping is performed.

[0164] Among them, the judgment value of the current in the lead wire current judgment equation can generally be taken as 0.04In, where In is the rated current of 5A or 1A.

[0165] Step 205, if the small difference differential current mutation ratio braking does not satisfy the T zone protection action equation corresponding to the small difference differential current mutation ratio braking, it is determined that the fault occurs in the dead zone of the lead-out line isolation switch, and the fault is removed by remotely tripping the lead-out line circuit breaker on the transformer side of the overcurrent protection.

[0166] Finally, after judging whether the differential current ratio braking of large difference, the differential current mutation ratio braking of small difference and the differential current of large difference all meet the preset T zone protection action equation, if the differential current mutation ratio braking of small difference does not meet the T zone protection action equation corresponding to the differential current mutation ratio braking of small difference, it is determined that the fault occurs in the dead zone of the lead-out line isolation switch. At this time, the lead-out line isolation switch is in the separated state, the differential current mutation ratio braking protection of small difference does not operate, and the fault is removed by the overcurrent protection remote tripping line transformer side lead-out line circuit breaker.

[0167] It should be noted that the ratio braking algorithm of the present application can be a sampling point algorithm or a phasor algorithm, which does not affect the result of the protection action.

[0168] By applying the technical solution of this embodiment, the differential current of the large difference mutation sampling value is calculated, and it is determined whether the differential current of the large difference mutation sampling value satisfies the preset fault judgment equation. If it does, it is determined that there is a fault in the T zone. When there is a fault in the T zone, the differential current of the large difference, the braking current of the large difference, the differential current mutation of the small difference, and the braking current mutation of the small difference are calculated respectively, and the braking coefficient is set. The present application takes into account that under normal operation, if the lead-out line isolation knife switch is closed, the differential current of the small difference is not connected to all the currents, so it is an incomplete differential current. Therefore, the differential current and braking current of the small difference use the current mutation, which can eliminate the influence of the differential current under normal operation and improve the sensitivity of the protection. After respectively calculating the differential current of large difference, the braking current of large difference, the differential current mutation of small difference, and the braking current mutation of small difference, and setting the braking coefficient, it is determined whether the differential current ratio braking of large difference, the differential current mutation ratio braking of small difference, and the differential current of large difference meet the corresponding T zone protection action equations according to the differential current of large difference, the braking current of large difference, the differential current mutation of small difference, and the braking coefficient. If all meet, it is determined that the fault occurs in the entire T zone. At this time, the differential current ratio braking protection of large difference and the differential current mutation ratio braking protection of small difference are simultaneously operated, the bus side trips the circuit breaker to remove the fault, and the preset lead line current discrimination equation is used to determine whether the lead line on the line transformer side has current. If the lead line on the line transformer side has current, the fault is removed by remote tripping the lead line circuit breaker on the line transformer side. If there is no current on the lead line on the line transformer side, no remote tripping is performed. If the ratio braking of the differential current mutation of the small difference does not satisfy the T-zone protection action equation corresponding to the ratio braking of the differential current mutation of the small difference, it is determined that the fault occurs in the dead zone of the lead-out isolation switch. At this time, the fault is removed by the overcurrent protection remote tripping line transformer side lead-out circuit breaker. In the present application, all discrimination is achieved through electrical quantities, and there is no need for isolation switch verification and coordination. Therefore, it is avoided that the existing differential protection scheme is heavily dependent on the isolation switch position. Once the isolation switch position is abnormal, the two-side or three-side differential function of the differential protection cannot be correctly put into use, and the tripping behavior of the protection cannot be guaranteed, which may cause problems such as multiple tripping circuit breakers or mis-cutting of loads. The reliability and safety of T-zone protection are improved.

[0169] Further, as Figure 1 The specific implementation of the method, the embodiment of the present application provides a differential protection device for T zone fault, such as Figure 8 As shown, the device comprises:

[0170] A calculation module, used for calculating a large-difference mutation amount sampling value differential current, and judging whether there is a fault in the T zone based on the mutation amount sampling value differential current;

[0171] A judgment module, used for judging whether the differential current ratio braking of the large difference, the differential current mutation ratio braking of the small difference and the differential current of the large difference all satisfy the preset T zone protection action equation if a fault exists;

[0172] A removal module is used to determine that the fault occurs in the entire T zone if all conditions are met, and the busbar side circuit breaker is tripped to remove the fault, and to determine whether there is current on the lead-out line on the line transformer side through a preset lead-out line current discrimination equation. If there is current on the lead-out line, the fault is removed by remotely tripping the lead-out line circuit breaker on the line transformer side;

[0173] The remote trip module is used to determine that the fault occurs in the dead zone of the lead-out line isolation switch if the ratio braking of the differential current mutation amount of the small difference does not satisfy the T-zone protection action equation corresponding to the ratio braking of the differential current mutation amount of the small difference, and then cut off the fault by remotely tripping the lead-out line circuit breaker on the transformer side of the line through overcurrent protection.

[0174] Optionally, the calculation formula of the mutation amount sampling value differential current is as follows:

[0175] Δ(I1+I2+I3)=||(I1+I2+I3) K -(I1+I2+I3) K-T |-|(I1+I2+I3) K-T -(I1+I2+I3) K-2T ||

[0176] Among them, I1 represents the circuit breaker current on the bus side, I2 represents the circuit breaker current on the bus side, I3 represents the lead-out line current on the line transformer side, K represents the current time, KT represents the time one week ago, K-2T represents the time two weeks ago, and T represents the number of sampling points per week.

[0177] Optionally, the computing module is further used for:

[0178] It is determined whether the differential current of the sudden change sampling value satisfies a preset fault determination equation. If so, it is determined that there is a fault in the T zone, wherein the fault determination equation is as follows:

[0179] Δ(I1+I2+I3)>I d0

[0180] Among them, Δ(I1+I2+I3) represents the differential current of the sudden change sampling value, I d0 Indicates the differential current threshold value.

[0181] Optionally, the judging module is further configured to:

[0182] Calculate the differential current of large difference, the braking current of large difference, the differential current mutation of small difference, the braking current mutation of small difference respectively, and set the braking coefficient;

[0183] Based on the differential current of the large difference, the braking current of the large difference, the differential current mutation of the small difference, the braking current mutation of the small difference and the braking coefficient, it is determined whether the differential current ratio braking of the large difference, the differential current mutation ratio braking of the small difference and the differential current of the large difference all satisfy the T-zone protection action equation, wherein the T-zone protection action equation corresponding to the differential current ratio braking of the large difference is as follows:

[0184] I dd >K*I fd

[0185] The T-zone protection action equation corresponding to the small differential current sudden change ratio braking is as follows:

[0186] ΔI dx >K*ΔI fx

[0187] The T-zone protection action equation corresponding to the large differential current is as follows:

[0188] I dd >I d0

[0189] Among them, I dd Indicates the large differential current, K indicates the braking coefficient, I fd Indicates the braking current of large difference, ΔI dx Indicates the differential current mutation amount of small difference, ΔI fx Indicates the sudden change in braking current for a small difference.

[0190] Optionally, the calculation formula of the large differential current is as follows:

[0191] I dd =|I1+I2+I3|

[0192] The calculation formula of the large difference braking current is as follows:

[0193] I fd =|I1|+|I2|+|I3|

[0194] The calculation formula of the small difference differential current mutation is as follows:

[0195] ΔI dx =|I dx -I dx-T |

[0196] Among them, I dx The differential current, I, represents the small difference in the current cycle dx-T A differential current representing a small difference from the previous cycle;

[0197] The calculation formula of the sudden change of braking current of the small difference is as follows:

[0198] ΔI fx =|I fx -I fx-T |

[0199] Among them, I fx Indicates the braking current of the small difference in the current cycle, I fx-T Indicates the braking current of the small difference from the previous cycle.

[0200] Optionally, the calculation formula of the small difference differential current is as follows:

[0201] I dx =|I1+I2|

[0202] The calculation formula of the braking current of the small difference is as follows:

[0203] I fx =|I1|+|I2|

[0204] Optionally, the lead-out line flow discriminant equation is as follows:

[0205] max{I 3A ,I 3B ,I 3C}>I minset

[0206] Among them, I 3A Indicates the A-phase current of the lead wire on the line transformer side, I 3B Indicates the phase B current of the lead wire on the line transformer side, I 3C Indicates the phase C current of the lead wire on the line transformer side, I minset Indicates the current determination value.

[0207] It should be noted that for other corresponding descriptions of the functional units involved in the differential protection device for T zone fault provided in the embodiment of the present application, reference can be made to Figure 4 and Figure 6 The corresponding description in the method will not be repeated here.

[0208] The present application also provides a computer device, which may be a personal computer, a server, a network device, etc. Fig. 9As shown, the computer device includes a bus, a processor, a memory and a communication interface, and may also include an input and output interface and a display device. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store location information. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, the steps in each method embodiment are implemented.

[0209] Those skilled in the art will understand that Fig. 9 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0210] In one embodiment, a computer-readable storage medium is provided. The computer-readable storage medium may be non-volatile or volatile, and stores a computer program thereon. When the computer program is executed by a processor, the steps in the above-mentioned method embodiments are implemented.

[0211] In one embodiment, a computer program product is provided, including a computer program, which implements the steps in the above method embodiments when executed by a processor.

[0212] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0213] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but are not limited to this.

[0214] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0215] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A differential protection method for T zone faults, characterized in that: include: Calculate the large-difference mutation amount sampling value differential current, and determine whether there is a fault in the T zone based on the mutation amount sampling value differential current; If there is a fault, it is determined whether the differential current ratio braking of the large difference, the differential current mutation ratio braking of the small difference and the differential current of the large difference all meet the preset T-zone protection action equation; If all conditions are met, it is determined that the fault occurs in the entire T zone, the busbar side circuit breaker is tripped to remove the fault, and the preset lead-out line current discrimination equation is used to determine whether there is current in the lead-out line on the line transformer side. If there is current in the lead-out line, the fault is removed by remotely tripping the lead-out line circuit breaker on the line transformer side; If the small difference differential current mutation ratio braking does not satisfy the T zone protection action equation corresponding to the small difference differential current mutation ratio braking, it is determined that the fault occurs in the dead zone of the lead-out line isolation switch, and the lead-out line circuit breaker on the transformer side of the overcurrent protection remote tripping line is used to cut off the fault; The calculation formula of the mutation sampling value differential current is as follows: Δ(I1+I2+I3)=||(I1+I2+I3) K -(I1+I2+I3) K-T |-|(I1+I2+I3) K-T -(I1+I2+I3) K-2T || Among them, I1 represents the bus side circuit breaker current, I2 represents the bus side circuit breaker current, I3 represents the line transformer side lead-out current, K represents the current time, KT represents the time one week ago, K-2T represents the time two weeks ago, and T represents the number of sampling points per week; The determining whether there is a fault in the T zone based on the differential current of the mutation amount sampling value includes: It is determined whether the differential current of the sudden change sampling value satisfies a preset fault determination equation. If so, it is determined that there is a fault in the T zone, wherein the fault determination equation is as follows: Δ(I1+I2+I3)>I d0 Among them, Δ(I1+I2+I3) represents the differential current of the sudden change sampling value, I d0 Indicates the differential current threshold value.

2. The method according to claim 1, characterized in that If a fault occurs, it is determined whether the differential current ratio braking of the large difference, the differential current mutation ratio braking of the small difference, and the differential current of the large difference all meet the preset T-zone protection action equation, including: Calculate the differential current of large difference, the braking current of large difference, the differential current mutation of small difference, the braking current mutation of small difference respectively, and set the braking coefficient; Based on the differential current of the large difference, the braking current of the large difference, the differential current mutation of the small difference, the braking current mutation of the small difference and the braking coefficient, it is determined whether the differential current ratio braking of the large difference, the differential current mutation ratio braking of the small difference and the differential current of the large difference all satisfy the T-zone protection action equation, wherein the T-zone protection action equation corresponding to the differential current ratio braking of the large difference is as follows: I dd >K*I fd The T-zone protection action equation corresponding to the small differential current sudden change ratio braking is as follows: ΔI dx >K*ΔI fx The T-zone protection action equation corresponding to the large differential current is as follows: I dd >I d0 Among them, I dd Indicates the large differential current, K indicates the braking coefficient, I fd Indicates the braking current of large difference, ΔI dx Indicates the differential current mutation amount of small difference, ΔI fx Indicates the sudden change in braking current for a small difference.

3. The method according to claim 2, characterized in that The calculation formula of the large differential current is as follows: I dd =|I1+I2+I3| The calculation formula of the large difference braking current is as follows: I fd =|I1|+|I2|+|I3| The calculation formula of the small difference differential current mutation is as follows: ΔI dx =|I dx -I dx-T | Among them, I dx The differential current, I, represents the small difference in the current cycle dx-T A differential current representing a small difference from the previous cycle; The calculation formula of the sudden change of braking current of the small difference is as follows: ΔI fx =|I fx -I fx-T | Among them, I fx Indicates the braking current of the small difference in the current cycle, I fx-T Indicates the braking current of the small difference from the previous cycle.

4. The method according to claim 3, characterized in that The calculation formula of the differential current of the small difference is as follows: I dx =|I1+I2| The calculation formula of the braking current of the small difference is as follows: I fx =|I1|+|I2|。 5. The method according to claim 1, characterized in that The lead-out line flow discriminant equation is as follows: max{I 3A ,I 3B ,I 3C }>I minset Among them, I 3A Indicates the A-phase current of the lead wire on the line transformer side, I 3B Indicates the phase B current of the lead wire on the line transformer side, I 3C Indicates the phase C current of the lead wire on the line transformer side, I minset Indicates the current determination value.

6. A differential protection device for T zone fault, characterized in that: The device comprises: A calculation module, used for calculating a large-difference mutation amount sampling value differential current, and judging whether there is a fault in the T zone based on the mutation amount sampling value differential current; A judgment module, used for judging whether the differential current ratio braking of the large difference, the differential current mutation ratio braking of the small difference and the differential current of the large difference all satisfy the preset T zone protection action equation if a fault exists; A removal module is used to determine that the fault occurs in the entire T zone if all conditions are met, and the busbar side circuit breaker is tripped to remove the fault, and to determine whether there is current on the lead-out line on the line transformer side through a preset lead-out line current discrimination equation. If there is current on the lead-out line, the fault is removed by remotely tripping the lead-out line circuit breaker on the line transformer side; A remote trip module is used to determine that the fault occurs in the dead zone of the lead-out line isolation switch if the ratio braking of the differential current mutation of the small difference does not satisfy the T-zone protection action equation corresponding to the ratio braking of the differential current mutation of the small difference, and then the lead-out line circuit breaker on the transformer side of the line is remotely tripped by overcurrent protection to cut off the fault; The calculation formula of the mutation sampling value differential current is as follows: Δ(I1+I2+I3)=||(I1+I2+I3) K -(I1+I2+I3) K-T |-|(I1+I2+I3) K-T -(I1+I2+I3) K-2T || Among them, I1 represents the bus side circuit breaker current, I2 represents the bus side circuit breaker current, I3 represents the line transformer side lead-out current, K represents the current time, KT represents the time one week ago, K-2T represents the time two weeks ago, and T represents the number of sampling points per week; The computing module is further used for: It is determined whether the differential current of the sudden change sampling value satisfies a preset fault determination equation. If so, it is determined that there is a fault in the T zone, wherein the fault determination equation is as follows: Δ(I1+I2+I3)>I d0 Among them, Δ(I1+I2+I3) represents the differential current of the sudden change sampling value, I d0 Indicates the differential current threshold value.

7. A storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 5 is implemented.

8. A computer device comprising a storage medium, a processor, and a computer program stored in the storage medium and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 5 is implemented.

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