FTU current direction control method, device and system

Abstract

The invention relates to the technical field of power distribution network protection and control, in particular to an FTU current direction control method, device and system, and the method comprises the steps: obtaining the line information of a distribution line; calculating the phase value of the three-phase current; judging a load transfer mode based on the fault identifier and the phase difference of the power supplies on the two sides of the interconnection circuit breaker; and executing a control strategy corresponding to the load transfer mode based on the first phase value. A load transfer mode is judged by measuring the phase of each phase of current of each section circuit breaker FTU in real time and combining closing and / or opening information of an upstream circuit breaker and an interconnection circuit breaker and system fault information, and automatic phase reversal in the reference direction of each phase of current of each section circuit breaker FTU is achieved by executing a control strategy corresponding to the load transfer mode. The method can truly reflect the change of the power supply mode, is very accurate in discrimination, and facilitates the safe and stable operation of a power grid.

Description

Technical Field

[0001] The present application relates to the technical field of protection and control of electric power distribution networks, and in particular to a FTU current direction control method, device and system. Background Art

[0002] In the high-voltage distribution line system, a segmented circuit breaker is generally used to divide the high-voltage distribution line into several segments for easy maintenance and fault isolation. The segmented circuit breaker close to the power supply end is called the upstream circuit breaker of the segmented circuit breaker far from the power supply end; the two substations are connected through a connecting line and a connecting circuit breaker. A FTU (Feeder Terminal Unit, distribution automation terminal) is installed on each circuit breaker as a device for protecting high-voltage distribution line faults and realizing distribution network automation. The FTU is provided with a current reference direction. The FTU can detect current anomalies such as overcurrent and short circuit in time by monitoring the current value in the distribution line in real time and comparing it with the current reference direction, thereby triggering a fault alarm and isolation mechanism. In order to ensure the normal measurement of each phase current of the FTU and the fault detection and judgment, the reference direction of each phase current of the FTU is specified: the positive direction of the current is from the main power supply end to the load end.

[0003] Therefore, whether the reference direction of the current on the FTU is correct plays a key role in the FTU's ability to correctly measure and identify faults. When the power supply changes, the reference direction of the FTU current on the corresponding section circuit breaker also needs to be changed accordingly, otherwise the FTU is prone to misjudgment and malfunction.

[0004] However, the traditional method is to manually adjust the reference direction of the current on the FTU, which cannot be automated or adaptive and has low efficiency. Summary of the invention

[0005] The present application aims to at least solve one of the technical problems in the prior art or related art that the traditional method is to use manual methods to adjust the reference direction of the current on the FTU, which cannot be automated or adaptive and has low efficiency.

[0006] To this end, the present application provides a FTU current direction control method, which measures the phase of each phase current of each section circuit breaker FTU in real time, combines the closing and / or opening information of the upstream circuit breaker and the connecting circuit breaker, and the system fault information to determine the load transfer mode, and executes the corresponding control strategy of the load transfer mode, thereby achieving automatic reversal of the reference direction of each phase current of each section circuit breaker FTU. The present application can truly reflect the changes in the power supply mode, and the judgment is very accurate, which is conducive to the safe and stable operation of the power grid.

[0007] The present application also provides a FTU current direction control device and system including this method.

[0008] According to an embodiment of the first aspect of the present application, a FTU current direction control method is provided, including:

[0009] Obtaining line information of the power distribution line, the line information at least includes: three-phase voltage value, three-phase current value, fault information, and phase difference value of power supplies on both sides of the tie circuit breaker;

[0010] Calculate the phase values ​​of the three-phase current based on the three-phase voltage values ​​and the three-phase current values;

[0011] Record the phase value of the three-phase current at the current moment as the first phase value;

[0012] Based on the fault information and the phase difference between the power supplies on both sides of the tie circuit breaker, a load transfer mode is determined, where the load transfer mode includes: a fault transfer mode, a power failure transfer mode, and an operation transfer mode;

[0013] Based on the first phase value, the FTU current reference direction is controlled to operate in reverse by executing a control strategy corresponding to the load transfer mode.

[0014] Optionally, the step of determining the load transfer mode includes:

[0015] Based on the fault identification, determine whether there is fault information;

[0016] If yes, the load transfer mode is the failover mode;

[0017] If not, determine whether the phase difference between the power supplies on both sides of the interconnecting circuit breaker is 0°;

[0018] When the phase difference between the power supplies on both sides of the tie circuit breaker is 0°, the load transfer mode is the operation transfer mode;

[0019] When the phase difference between the power supplies on both sides of the interconnecting circuit breaker is not 0°, the load transfer mode is the power failure transfer mode.

[0020] Optionally, when the load transfer mode is a fault transfer mode, the control strategy includes a fault control strategy corresponding to the fault transfer mode, and the fault control strategy is used to control the FTU current reference direction to operate in reverse when a fault occurs in the distribution line to transfer the load;

[0021] Based on the first phase value, the FTU current reference direction is controlled to be reversed by executing a control strategy corresponding to the load transfer mode, including:

[0022] When it is detected that the upstream circuit breaker changes from the closed position to the open position, the three-phase voltage value at the moment when the upstream circuit breaker changes is recorded as the first voltage value;

[0023] When it is detected that the connecting circuit breaker changes from the open position to the closed position, the three-phase voltage value at the time when the connecting circuit breaker changes is recorded as the second voltage value, and at the same time, the phase value of the three-phase current at the time when the connecting circuit breaker changes is recorded as the second phase value;

[0024] When the first voltage value is less than the voltage threshold, and the second voltage value is greater than the voltage threshold, and the difference between the second phase value and the first phase value is within the first phase threshold range, the FTU current reference direction inversion operation is performed.

[0025] Optionally, when the load transfer mode is a fault transfer mode, the control strategy includes a fault control strategy corresponding to the fault transfer mode, and the fault control strategy is used to control the FTU current reference direction to operate in reverse when a fault occurs in the distribution line to transfer the load;

[0026] Based on the first phase value, the FTU current reference direction is controlled to reversely operate by executing a control strategy corresponding to the load transfer mode, and further comprising:

[0027] The record starts from the time when the upstream circuit breaker is detected to change from the closed position to the open position, and ends when the connecting circuit breaker is detected to change from the open position to the closed position. The elapsed time is the first transfer time;

[0028] When the first transfer time is within the first time threshold range, the first voltage value is less than the voltage threshold, the second voltage value is greater than the voltage threshold, and the difference between the second phase value and the first phase value is within the first phase threshold range, the FTU current reference direction inversion operation is performed.

[0029] Optionally, when the load transfer mode is a power outage transfer mode, the control strategy includes a power outage control strategy corresponding to the power outage transfer mode, and the power outage control strategy is used to control the FTU current reference direction to reverse operation when a power outage occurs in the distribution line to transfer the load;

[0030] Based on the first phase value, the FTU current reference direction is controlled to be reversed by executing a control strategy corresponding to the load transfer mode, including:

[0031] When the opening information of the upstream circuit breaker or the connecting circuit breaker is detected first, the three-phase voltage value at the moment of the opening change is recorded as the third voltage value;

[0032] When the closing information of the tie circuit breaker or the upstream circuit breaker is detected later, the three-phase voltage value at the moment of closing change is recorded as a fourth voltage value, and at the same time, the phase value of the three-phase current at the moment of closing change is recorded as a third phase value;

[0033] When the third voltage value is less than the voltage threshold, and the fourth voltage value is greater than the voltage threshold, and the difference between the third phase value and the first phase value is within the first phase threshold range, the FTU current reference direction inversion operation is performed.

[0034] Optionally, when the load transfer mode is a power outage transfer mode, the control strategy includes a power outage control strategy corresponding to the power outage transfer mode, and the power outage control strategy is used to control the FTU current reference direction to reverse operation when a power outage occurs in the distribution line to transfer the load;

[0035] Based on the first phase value, the FTU current reference direction is controlled to reversely operate by executing a control strategy corresponding to the load transfer mode, and further comprising:

[0036] The recording starts from when the opening information is detected and ends when the closing information is detected. The elapsed time is the second transfer time.

[0037] When the second transfer time is within the second time threshold range, the third voltage value is less than the voltage threshold, the fourth voltage value is greater than the voltage threshold, and the difference between the third phase value and the first phase value is within the first phase threshold range, the FTU current reference direction inversion operation is performed.

[0038] Optionally, when the load transfer mode is the operation transfer mode, the control strategy includes an operation control strategy corresponding to the operation transfer mode, and the operation control strategy is used to control the FTU current reference direction to reverse the phase when the distribution line has a closing and unclosing operation to transfer the load;

[0039] Based on the first phase value, the FTU current reference direction is controlled to be reversed by executing a control strategy corresponding to the load transfer mode, including:

[0040] When the closing information of the upstream circuit breaker or the connecting circuit breaker is detected first, and the opening information of the connecting circuit breaker or the upstream circuit breaker is detected later, the phase value of the three-phase current at the moment after the opening change is recorded as the fourth phase value;

[0041] When the difference between the fourth phase value and the first phase value is within the first phase threshold range, an FTU current reference direction inversion operation is performed.

[0042] Optionally, when the load transfer mode is the operation transfer mode, the control strategy includes an operation control strategy corresponding to the operation transfer mode, and the operation control strategy is used to control the FTU current reference direction to reverse the phase when the distribution line has a closing and unclosing operation to transfer the load;

[0043] Based on the first phase value, the FTU current reference direction is controlled to reversely operate by executing a control strategy corresponding to the load transfer mode, and further comprising:

[0044] The recording starts from when the closing information is detected and ends when the opening information is detected. The elapsed time is the third transfer time.

[0045] When the third transfer time is within the third time threshold range and the difference between the fourth phase value and the first phase value is within the first phase threshold range, the FTU current reference direction inversion operation is performed.

[0046] A second aspect of the present application provides a FTU current direction control device, including:

[0047] An acquisition module is used to acquire line information of a distribution line, the line information including at least: three-phase voltage value, three-phase current value, fault identification, and phase difference value of power supplies on both sides of the tie circuit breaker;

[0048] A calculation module, used for calculating the phase value of the three-phase current based on the three-phase voltage value and the three-phase current value; recording the phase value of the three-phase current at the current moment as the first phase value;

[0049] A judgment module, used to judge a load transfer mode based on a fault identifier and a phase difference between power supplies on both sides of the tie circuit breaker, wherein the load transfer mode includes: a fault transfer mode, a power failure transfer mode, and an operation transfer mode;

[0050] The execution module is used to control the FTU current reference direction to reverse the operation based on the first phase value by executing the control strategy corresponding to the load transfer mode.

[0051] The third aspect of the present application provides a FTU current direction control system, including:

[0052] The FTU unit is configured to collect line information of the distribution line, the line information at least including: three-phase voltage value, three-phase current value, fault identification, and phase difference value of power supplies on both sides of the tie circuit breaker;

[0053] A controller is configured to execute a FTU current direction control method as described in the first aspect or its various implementations.

[0054] One of the above technical solutions has at least the following advantages or beneficial effects:

[0055] For an FTU current direction control method of an embodiment of the present application, the method includes: obtaining line information of a distribution line, the line information includes at least: three-phase voltage value, three-phase current value, fault mark, and phase difference value of power supplies on both sides of a connecting circuit breaker; based on the three-phase voltage value and the three-phase current value, calculating the phase value of the three-phase current; recording the phase value of the three-phase current at the current moment as a first phase value; based on the fault mark and the phase difference value of the power supplies on both sides of the connecting circuit breaker, judging a load transfer mode, the load transfer mode including: one of a fault transfer mode, a power outage transfer mode, and an operation transfer mode; based on the first phase value, by executing a control strategy corresponding to the load transfer mode, controlling the FTU current reference direction to reverse operation. By measuring the phase of each phase current of each section circuit breaker FTU in real time, combining the closing and / or opening information of the upstream circuit breaker and the connecting circuit breaker, and the system fault information, the load transfer mode is judged, and the corresponding control strategy of the load transfer mode is executed, thereby achieving automatic reversal of the reference direction of each phase current of each section circuit breaker FTU. This application can truly reflect the changes in the power supply mode, and the judgment is very accurate, which is conducive to the safe and stable operation of the power grid.

[0056] An FTU current direction control device and system provided in an embodiment of the present application is provided with the method described above. Since the method has the above-mentioned technical effect, an FTU current direction control device and system provided with the method should also have corresponding technical effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A schematic flow chart of a FTU current direction control method provided in an embodiment of the present application is shown;

[0058] Figure 2 A schematic diagram of a flow chart for determining a load transfer mode in a FTU current direction control method provided in an embodiment of the present application is shown;

[0059] Figure 3 A schematic diagram of a power distribution line system provided in an embodiment of the present application is shown;

[0060] Figure 4 A schematic diagram of a FTU current direction control device provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0062] As mentioned above, the voltage level of high-voltage distribution lines is 6kV to 35kV, and the grounding methods include ungrounded system, arc suppression coil grounding system, and low resistance grounding system. In a schematic 10kV distribution line system, Figure 3 As shown, there are two substations, A substation and B substation, supplying power. Interconnection lines m and n are set between the two substations. Line m and line n are connected by an interconnection circuit breaker. Sectional circuit breakers 1, 2 and 3 are respectively provided on line m and line n. Among them, sectional circuit breaker 1 is closer to the substation, i.e., the power supply end. Sectional circuit breaker 1 is the upstream circuit breaker of sectional circuit breaker 2 and sectional circuit breaker 3. Similarly, sectional circuit breaker 2 and sectional circuit breaker 3 are the downstream circuit breakers of sectional circuit breaker 1. Sectional circuit breakers can communicate vertically to transmit information such as position changes of upstream circuit breakers and interconnection circuit breakers.

[0063] Normally, the interconnecting circuit breaker is in hot standby state, that is, the disconnectors on both sides of the circuit breaker are closed and the interconnecting circuit breaker is disconnected. When the equipment of the section circuit breaker of line m of substation A needs to be repaired or part of line m needs to be repaired, the remaining downstream lines are transferred to substation B for power supply (abbreviated as: power transfer) through the interconnecting circuit breaker when the line m or part of the line is under maintenance. This operation process is called closing and opening operation. When a section of the distribution line m of the A substation fails, the downstream line of the faulty line m needs to be transferred to the B substation for power supply through the connecting circuit breaker after the protection and FTU isolate the fault; the power supply has changed, that is, the topological relationship of each segmented circuit breaker on the line m has changed. In order to further correctly identify the fault, it is necessary to change the reference direction of the three-phase current of the FTU on the segmented circuit breaker on the A substation line m or the downstream line after the fault cuts off part of the line segment, from the A substation bus to the B substation bus (referred to as the current reference direction reversal), that is, the power supply has changed, and the current reference direction of the FTU on the corresponding segmented circuit breaker also needs to be changed (reversed). This current reference direction reversal method is to enable the FTU on the segmented circuit breaker on these remaining lines to correctly measure and identify the fault, otherwise it is easy to misjudge and cause malfunction.

[0064] However, the traditional method is to manually adjust the direction of the current reference direction on the FTU, which cannot be automated or adaptive and has low efficiency.

[0065] In order to solve at least one of the technical problems existing in the prior art or related technology, the present application provides a FTU current direction control method, device and system, the method comprising: obtaining line information of a distribution line, the line information comprising at least: three-phase voltage value, three-phase current value, fault mark, and phase difference value of the power supply on both sides of the interconnecting circuit breaker; calculating the phase value of the three-phase current based on the three-phase voltage value and the three-phase current value; recording the phase value of the three-phase current at the current moment as a first phase value; judging the load transfer mode based on the fault mark and the phase difference value of the power supply on both sides of the interconnecting circuit breaker, the load transfer mode comprising: one of a fault transfer mode, a power outage transfer mode and an operation transfer mode; based on the first phase value, controlling the FTU current reference direction to reverse the operation by executing the corresponding control strategy of the load transfer mode. By measuring the phase of each phase current of each section circuit breaker FTU in real time, combining the closing and / or opening information of the upstream circuit breaker and the connecting circuit breaker, and the system fault information, the load transfer mode is judged, and the corresponding control strategy of the load transfer mode is executed, thereby achieving automatic reversal of the reference direction of each phase current of each section circuit breaker FTU. This application can truly reflect the changes in the power supply mode, and the judgment is very accurate, which is conducive to the safe and stable operation of the power grid.

[0066] The following describes the FTU current direction control method, device and system according to some embodiments provided by the present application with reference to the accompanying drawings.

[0067] See also Figures 1 to 4 , a FTU current direction control method provided by an embodiment of the first aspect of the present application includes:

[0068] S100: Acquire line information of a power distribution line, where the line information includes at least: three-phase voltage value, three-phase current value, fault identification, and phase difference value of power supplies on both sides of a tie circuit breaker;

[0069] The FTU is equipped with a current transformer (CT) and a voltage transformer (PT). The CT can measure the three-phase current value in real time. Since the 10kV distribution line system is a high-voltage line, it is impossible to directly measure the three-phase voltage. The single-phase voltage on the power supply side of the section circuit breaker can only be measured through the PT on both sides of the section circuit breaker. And, the single-phase voltage on the load side of the section circuit breaker Then the third line voltage is calculated in real time The calculation formula is as follows:

[0070]

[0071] In formula (1), The third line voltage, It is the voltage measured by the single-phase PT on the power supply side of the section circuit breaker. It is the voltage measured by the single-phase PT on the load side of the section circuit breaker.

[0072] Fault information includes: single-phase grounding fault and phase-to-phase short circuit fault. When a single-phase grounding fault occurs, a zero-sequence voltage will be generated; when a phase-to-phase short circuit fault occurs, one or three phase-to-phase voltages will drop below the voltage threshold. Therefore, when the FTU detects that the zero-sequence voltage value is greater than the fault threshold, or the phase-to-phase voltage is less than the voltage threshold, and then receives a trip command signal from the upstream section switch's feeder automation (FA), the FTU will issue a fault message. When there is fault information, the fault indicator is 1; when there is no fault information, the fault indicator is 0.

[0073] The zero-sequence voltage value 3U0 refers to the vector sum of the three-phase voltages. In a three-phase power system, the three-phase voltages are equal but the phases are 120 degrees apart, and the sum of the voltages is zero. Therefore, under normal operating conditions, the zero-sequence voltage value 3U0 is usually very small, usually not exceeding 1% of the total voltage.

[0074] The phase difference between the power supplies on both sides of the interconnecting circuit breaker, that is, the phase difference between power supply station A and power supply station B, is fixed in the distribution line. Generally, the phase difference is 0° or 30°. When the phase difference is 0°, the closing and opening operations can be performed directly when power is transferred between power supply station A and power supply station B; when the phase difference is 30°, that is, not 0°, the closing and opening operations cannot be performed directly when power is transferred between power supply station A and power supply station B, and power outage is required for operation.

[0075] S200: Calculate the phase value of the three-phase current based on the three-phase voltage value and the three-phase current value; and record the phase value of the three-phase current at the current moment as the first phase value.

[0076] The formula for calculating the phase value of the three-phase current is as follows:

[0077]

[0078] In formula (2), is the phase angle of the A-phase, B-phase, and C-phase currents, is the single-phase PT voltage on both sides of the section circuit breaker And calculate the third line voltage in real time A phase current Phase B current Phase C current Φ is represented by A, B, C; ΦΦ is represented by AB, BC, CA.

[0079] When the power supply is normal, the phase value of the three-phase current is recorded in real time as the first phase value.

[0080] S300: Based on the fault identification and the phase difference between the power supplies on both sides of the tie circuit breaker, determine a load transfer mode, where the load transfer mode includes: a fault transfer mode, a power failure transfer mode, and an operation transfer mode.

[0081] When power is transferred between power supply station A and power supply station B, the load transfer mode needs to be determined first. The fault transfer mode is due to a ground fault or a phase-to-phase fault; the power outage transfer mode requires a power outage operation; and the operation transfer mode requires a closing and opening operation.

[0082] In an exemplary embodiment, based on the fault identification and the phase difference between the power supplies on both sides of the tie circuit breaker, the step of determining the load transfer mode includes:

[0083] S310: judging whether there is fault information based on the fault identifier;

[0084] If yes, the load transfer mode is failover mode.

[0085] When the fault flag is detected as 1, it means that there is fault information. When a ground fault occurs, the zero-sequence voltage value will increase because the three-phase voltage is no longer balanced. When a phase, such as phase A, has a ground fault, the voltage of phase A will suddenly decrease or become zero, while the voltage of phases B and C will increase. This imbalance will cause the zero-sequence voltage to increase. The FTU will detect that the zero-sequence voltage value is greater than the fault threshold, and then receive a signal from the distribution network automation (FA) of the upstream section switch to issue a trip command. The FTU will issue a fault message, and the fault flag is 1 at this time; interphase fault refers to a short circuit between two or more phases. For example, if a short circuit occurs between phases A and B, the voltage of these two phases will drop rapidly. The FTU will detect that the interphase voltage is less than the voltage threshold, and then receive a signal from the distribution network automation (FA) of the upstream section switch to issue a trip command. The FTU will issue a fault message, and the fault flag is 1 at this time.

[0086] The fault threshold is determined based on the maximum unbalanced voltage value when the section circuit breaker FTU measures the zero-sequence voltage during normal operation. When the zero-sequence voltage value is greater than the fault threshold, it indicates that a ground fault has occurred in the line.

[0087] The fault threshold is calculated as follows:

[0088] 3U 0zd =K k *3U bph (3)

[0089] 3U in formula (3) 0zd is the fault threshold; Kk is the reliability coefficient, which can be 1.5 to 2; 3U bph It is the maximum unbalanced voltage value when the section circuit breaker FTU measures the zero-sequence voltage during normal operation.

[0090] S320: If not, determine whether the phase difference between the power supplies on both sides of the interconnecting circuit breaker is 0°; when the phase difference between the power supplies on both sides of the interconnecting circuit breaker is 0°, the load transfer mode is the operation transfer mode; when the phase difference between the power supplies on both sides of the interconnecting circuit breaker is not 0°, the load transfer mode is the power outage transfer mode.

[0091] When the fault mark is 0, it means there is no fault information, and there is no ground fault or phase-to-phase fault in the line. At this time, the power transfer between power supply station A and power supply station B is manually operated. The phase difference between power supply station A and power supply station B determines whether to use the closing and opening ring operation mode or the power outage operation mode. When the phase difference is 0°, the closing and opening ring operation can be directly performed when the power is transferred between power supply station A and power supply station B; when the phase difference is 30°, that is, not 0°, the closing and opening ring operation cannot be directly performed when the power is transferred between power supply station A and power supply station B, and the power outage is required for operation.

[0092] S400: Based on the first phase value, the FTU current reference direction is controlled to be reversed by executing a control strategy corresponding to the load transfer mode.

[0093] The control strategies include the fault control strategy corresponding to the fault transfer mode, the power outage control strategy corresponding to the power outage transfer mode, and the operation control strategy corresponding to the operation transfer mode; the fault control strategy is used to control the FTU current reference direction to reverse operation when a fault occurs in the distribution line to transfer the load; the power outage control strategy is used to control the FTU current reference direction to reverse operation when a power outage occurs in the distribution line to transfer the load; the operation control strategy is used to control the FTU current reference direction to reverse operation when a closing and unclosing operation occurs in the distribution line to transfer the load. Formulating specific control strategies for different load transfer modes can more accurately adjust the operating status of the distribution system, thereby effectively reducing the instability factors of the system.

[0094] S410: When the load transfer mode is the fault transfer mode, the control strategy includes a fault control strategy corresponding to the fault transfer mode, and the fault control strategy is used to control the FTU current reference direction to reverse the operation when a fault transfer load occurs in the distribution line; based on the first phase value, by executing the control strategy corresponding to the load transfer mode, the FTU current reference direction is controlled to reverse the operation, including:

[0095] S411: When it is first detected that the upstream circuit breaker changes from the closed position to the open position, the three-phase voltage value at the moment when the upstream circuit breaker changes is recorded as a first voltage value.

[0096] When a ground fault occurs in the line, for example, when a ground fault occurs between section circuit breaker 1 and section circuit breaker 2 on the 10 kV line m of substation A, section circuit breaker 3 will detect that the zero-sequence voltage value is greater than the fault threshold.

[0097] In order to protect the line, the distribution network automation (FA) will change the section circuit breaker 1 and the section circuit breaker 2 from the closed position to the open position after a necessary delay, that is, disconnect the section circuit breaker 1 and the section circuit breaker 2, so that there is no power supply in the line for maintenance. At this time, the section circuit breaker 3 will receive the opening information of the upstream circuit breaker from the closed position to the open position, send out a fault information, and enter the fault transfer mode. The section circuit breaker 3 records the three-phase voltage value after the section circuit breaker 1 and the section circuit breaker 2 are disconnected as the first voltage value.

[0098] Since the upstream circuit breaker is disconnected and there is no power supply, the first voltage value at this time will be smaller than the voltage threshold.

[0099] The voltage threshold is generally determined by the low voltage of the section circuit breaker FTU when a two-phase short circuit occurs at the end of the line. The calculation formula is as follows:

[0100] U ΦΦ.zd ≤K k *U x.e (4)

[0101] In formula (4), U ΦΦ.zd is the voltage threshold, generally set to 60~75V; K k is the reliability coefficient, generally ranging from 0.6 to 0.75; U x.e The secondary rated line voltage of the 10kV PT is taken as 100V.

[0102] S412: When it is detected that the connecting circuit breaker changes from the open position to the closed position, the three-phase voltage value at the time of the connecting circuit breaker change is recorded as a second voltage value, and at the same time, the phase value of the three-phase current at the time of the connecting circuit breaker change is recorded as a second phase value.

[0103] In order not to affect the user's electricity consumption, FA will close the connecting circuit breaker after a necessary delay, so that the power supply of the section circuit breaker 3 is transferred from the A power supply station to the B power supply station. At this time, the section circuit breaker 3 will receive the closing information that the connecting circuit breaker changes from the open position to the closed position, that is, the connecting circuit breaker is closed. The section circuit breaker 3 records the three-phase voltage value after the connecting circuit breaker is closed as the second voltage value. At the same time, the phase value of the three-phase current after the connecting circuit breaker is closed is recorded as the second phase value. The calculation formula of the second phase value is the same as formula (2), which will not be repeated here.

[0104] S413: Recording starts from when the upstream circuit breaker is detected to change from the closed position to the open position and ends when the connecting circuit breaker is detected to change from the open position to the closed position. The elapsed time is the first transfer time.

[0105] The time from the start of the fault to the downstream section circuit breaker of the fault becoming open and the connecting circuit breaker becoming closed is generally 1.5 to 5 minutes. Therefore, the first time threshold range can be set to 1.5 to 5 minutes. Recording the first transfer time can assist in determining whether the current load transfer mode is correct. When the first transfer time is not within the first time threshold range, the load transfer mode needs to be re-determined to avoid errors in the execution of the control strategy.

[0106] S414: When the first transfer time is within the first time threshold range, the first voltage value is less than the voltage threshold, the second voltage value is greater than the voltage threshold, and the difference between the second phase value and the first phase value is within the first phase threshold range, perform an FTU current reference direction inversion operation.

[0107] When the interconnecting circuit breaker is closed and power supply is restored, the second voltage value at this time will be greater than the voltage threshold; at the same time, since the power supply is transferred from power supply station A to power supply station B, the difference between the second phase value and the first phase value will be 180°, that is, the first phase threshold can be designed to be 180±20°.

[0108] The calculation formula of the difference between the second phase value and the first phase value is as follows:

[0109]

[0110] In formula (5), is the first phase value recorded, is the second phase value recorded.

[0111] When all these conditions are met, the section circuit breaker 3 can confirm that the power supply has been transferred from the A power supply station to the B substation, and the FTU current reference direction reversal operation can be performed.

[0112] The FTU current reference direction reversal operation includes: after the delay time t1, the FTU current phase of the section circuit breaker is reversed and the protection setting value is adjusted to the setting value when the current phase is reached. The delay time t1 should be greater than the system disturbance time, generally 5 to 10 seconds.

[0113] S420: When the load transfer mode is a power outage transfer mode, the control strategy includes a power outage control strategy corresponding to the power outage transfer mode, and the power outage control strategy is used to control the FTU current reference direction to reverse the operation when a power outage occurs in the distribution line to transfer the load; based on the first phase value, by executing the control strategy corresponding to the load transfer mode, the FTU current reference direction is controlled to reverse the operation, including:

[0114] S421: When the opening information of the upstream circuit breaker or the connecting circuit breaker is detected first, the three-phase voltage value at the time after the opening change is recorded as the third voltage value.

[0115] When the fault indicator is 0, that is, no fault information is detected, and the phase difference between the power supplies on both sides of the interconnecting circuit breaker is not 0°, a power outage is required to transfer power. For example, when the power supply mode of section circuit breaker 2 on the 10kV line m of substation A needs to be adjusted, the power supply from substation A is transferred to substation B. At this time, section circuit breaker 2 enters the power outage transfer mode.

[0116] The power outage operation requires first changing the section circuit breaker 1 from the closed position to the open position, that is, disconnecting the section circuit breaker 1. At this time, the section circuit breaker 2 will receive the opening information that the upstream circuit breaker changes from the closed position to the open position. The section circuit breaker 2 records the three-phase voltage value after the section circuit breaker is disconnected as the third voltage value. Since there is no power supply, the third voltage value at this time will be less than the voltage threshold.

[0117] S422: When the closing information of the interconnecting circuit breaker or the upstream circuit breaker is detected later, the three-phase voltage value at the moment of closing change is recorded as a fourth voltage value, and at the same time, the phase value of the three-phase current at the moment of closing change is recorded as a third phase value.

[0118] After the section circuit breaker 1 is opened for a certain period of time, the connecting circuit breaker is closed, so that the power supply of the section circuit breaker 2 is transferred from the A power supply station to the B power supply station. At this time, the section circuit breaker 2 will receive the closing information that the connecting circuit breaker changes from the open position to the closed position, that is, the connecting circuit breaker is closed. The section circuit breaker 2 records the three-phase voltage value after the connecting circuit breaker is closed as the fourth voltage value. At the same time, the phase value of the three-phase current after the connecting circuit breaker is closed is recorded as the third phase value. The calculation formula of the third phase value is the same as formula (2), which will not be repeated here.

[0119] S423: Recording starts from when the opening information is detected and ends when the closing information is detected, and the elapsed time is the second transfer time.

[0120] The time for adjusting the power supply after a power outage is generally 30 to 60 minutes, so the second time threshold range can be set to 30 to 60 minutes. Recording the second transfer time can assist in determining whether the current load transfer mode is correct. When the second transfer time is not within the second time threshold range, the load transfer mode needs to be re-determined to avoid errors in the execution of the control strategy.

[0121] S424: When the second transfer time is within the second time threshold range, the third voltage value is less than the voltage threshold, the fourth voltage value is greater than the voltage threshold, and the difference between the third phase value and the first phase value is within the first phase threshold range, perform an FTU current reference direction inversion operation.

[0122] When the interconnecting circuit breaker is closed, power supply is restored, and the fourth voltage value at this time will be greater than the voltage threshold; at the same time, since the power supply is transferred from power supply station A to power supply station B, there is a 30° angle difference between the power supplies on both sides of the interconnecting circuit breaker, and the difference between the third phase value and the first phase value will be 150°, that is, the first phase threshold can be designed to be 150±20° or 210±20°. The calculation formula for the difference between the third phase value and the first phase value is the same as formula (5), which will not be repeated here.

[0123] When all these conditions are met, section circuit breaker 2 can confirm that power supply has been switched from power supply station A to substation B, and the FTU current reference direction reversal operation can be performed.

[0124] Similarly, when the section circuit breaker 2 needs to transfer the power supply from the B substation back to the A substation, the power outage operation needs to first change the connecting circuit breaker from the closed position to the open position, that is, disconnect the connecting circuit breaker. At this time, the section circuit breaker 2 will receive the opening information that the connecting circuit breaker changes from the closed position to the open position; then, close the section circuit breaker 1, so that the power supply of the section circuit breaker 2 is transferred from the B power supply station to the A power supply station. At this time, the section circuit breaker 2 will receive the closing information that the upstream circuit breaker changes from the open position to the closed position. That is to say, in the power outage transfer mode, after detecting the opening information of the upstream circuit breaker changing from the closed position to the open position, the closing information of the connecting circuit breaker changing from the open position to the closed position will continue to be detected, that is, the power supply is transferred from power supply station A to power supply station B; or, after detecting the opening information of the connecting circuit breaker changing from the closed position to the open position, the closing information of the upstream circuit breaker changing from the open position to the closed position will continue to be detected, that is, the power supply is transferred from power supply station B to power supply station A, and the remaining judgment steps are the same and will not be repeated here.

[0125] S430: When the load transfer mode is the operation transfer mode, the control strategy includes an operation control strategy corresponding to the operation transfer mode, and the operation control strategy is used to control the FTU current reference direction to reverse the phase when the distribution line has a ring closing and opening operation to transfer the load; based on the first phase value, by executing the control strategy corresponding to the load transfer mode, the FTU current reference direction is controlled to reverse the phase, including:

[0126] S431: First detect the closing information of the upstream circuit breaker or the interconnecting circuit breaker.

[0127] When the fault indicator is 0, that is, no fault information is detected, and the phase difference between the power supplies on both sides of the interconnecting circuit breaker is 0°, the power transfer requires a closing and opening operation. For example, when the section circuit breaker 3 on the 10kV line m of substation A needs to adjust the power supply mode, the power supply from substation A is transferred to substation B. At this time, the section circuit breaker 3 enters the operation transfer mode.

[0128] The closing and opening operation requires that the connecting circuit breaker be changed from the open position to the closed position first, that is, the connecting circuit breaker is closed. At this time, the section circuit breaker 3 will receive the closing information that the connecting circuit breaker is changed from the open position to the closed position. Since there will be no obvious change in voltage during the closing and opening operation, there is no need to judge the voltage situation.

[0129] S432: After detecting the opening information of the connecting circuit breaker or the upstream circuit breaker, the phase value of the three-phase current at the moment of the opening change is recorded as the fourth phase value.

[0130] When the tie circuit breaker is closed for a certain period of time, the section circuit breaker 2 is disconnected, so that the power supply of the section circuit breaker 3 is transferred from the A power supply station to the B power supply station. At this time, the section circuit breaker 3 will receive the opening information that the upstream circuit breaker changes from the closed position to the open position, that is, the upstream circuit breaker is disconnected. The section circuit breaker 3 records the phase value of the three-phase current after the upstream circuit breaker is disconnected as the fourth phase value. The calculation formula of the fourth phase value is the same as formula (2), which will not be repeated here.

[0131] S433: Recording starts from when the closing information is detected and ends when the opening information is detected. The elapsed time is the third transfer time.

[0132] The time for adjusting the power supply by closing and opening the ring is generally 10 to 60 minutes, so the third time threshold range can be set to 10 to 60 minutes. Recording the third transfer time can assist in determining whether the current load transfer mode is correct. When the third transfer time is not within the third time threshold range, the load transfer mode needs to be re-determined to avoid errors in the execution of the control strategy.

[0133] S434: When the third transfer time is within the third time threshold range, and the difference between the fourth phase value and the first phase value is within the first phase threshold range, perform an FTU current reference direction inversion operation.

[0134] When the upstream circuit breaker is disconnected, the closing and opening operation is completed. At this time, the power supply voltage will not change much. However, since the power supply is transferred from power supply station A to power supply station B, there is no angle difference between the power supplies on both sides of the interconnecting circuit breaker. The difference between the fourth phase value and the first phase value will be 180°, that is, the first phase threshold can be designed to be 180±20°. The calculation formula for the difference between the fourth phase value and the first phase value is the same as formula (5), which will not be repeated here.

[0135] When all these conditions are met, the section circuit breaker 3 can confirm that the power supply has been transferred from the A power supply station to the B substation, and the FTU current reference direction reversal operation can be performed.

[0136] Similarly, when the section circuit breaker 3 needs to switch the power supply from the B substation back to the A substation, the closing and unclosing operation needs to first change the section circuit breaker 2 from the open position to the closed position, that is, close the upstream section circuit breaker. At this time, the section circuit breaker 3 will receive the closing information that the upstream circuit breaker has changed from the open position to the closed position; then, disconnect the connecting circuit breaker, so that the power supply of the section circuit breaker 3 is transferred from the B power supply station to the A power supply station. At this time, the section circuit breaker 3 will receive the closing information that the connecting circuit breaker has changed from the closed position to the open position. That is to say, in the operation transfer mode, after detecting the closing information that the interconnecting circuit breaker changes from the open position to the closed position, the opening information that the upstream circuit breaker changes from the closed position to the open position will continue to be detected, that is, the power supply is transferred from the A power supply station to the B power supply station; or, after detecting the closing information that the upstream circuit breaker changes from the open position to the closed position, the opening information that the interconnecting circuit breaker changes from the closed position to the open position will continue to be detected, that is, the power supply is transferred from the B power supply station to the A power supply station, and the remaining judgment steps are the same and will not be repeated here.

[0137] The second aspect of the present application provides a FTU current direction control device, such as Figure 4 As shown, including:

[0138] An acquisition module 71 is used to acquire line information of a power distribution line, where the line information includes at least: three-phase voltage value, three-phase current value, fault identification, and phase difference value of power supplies on both sides of a tie circuit breaker;

[0139] A calculation module 72 is used to calculate the phase value of the three-phase current based on the three-phase voltage value and the three-phase current value; and record the phase value of the three-phase current at the current moment as a first phase value;

[0140] A judgment module 73, used to judge a load transfer mode based on the fault identification and the phase difference between the power supplies on both sides of the tie circuit breaker, the load transfer mode including: a fault transfer mode, a power failure transfer mode and an operation transfer mode;

[0141] The execution module 74 is used to control the FTU current reference direction to reverse the operation based on the first phase value by executing the control strategy corresponding to the load transfer mode.

[0142] In some embodiments of the present application, the judging module 73 is used to judge the load transfer mode based on the fault information and the phase difference between the power supplies on both sides of the tie circuit breaker, and the steps include:

[0143] Based on the fault identification, determine whether there is fault information;

[0144] If yes, the load transfer mode is the failover mode;

[0145] If not, determine whether the phase difference between the power supplies on both sides of the interconnecting circuit breaker is 0°;

[0146] When the phase difference between the power supplies on both sides of the tie circuit breaker is 0°, the load transfer mode is the operation transfer mode;

[0147] When the phase difference between the power supplies on both sides of the interconnecting circuit breaker is not 0°, the load transfer mode is the power failure transfer mode.

[0148] In some embodiments of the present application, the execution module 74 is used for, when the load transfer mode is the fault transfer mode, the control strategy includes a fault control strategy corresponding to the fault transfer mode, and the fault control strategy is used for, when a fault transfer load occurs in the distribution line, controlling the FTU current reference direction to operate in reverse phase;

[0149] Based on the first phase value, the FTU current reference direction is controlled to be reversed by executing a control strategy corresponding to the load transfer mode, including:

[0150] When it is detected that the upstream circuit breaker changes from the closed position to the open position, the three-phase voltage value at the moment when the upstream circuit breaker changes is recorded as the first voltage value;

[0151] When it is detected that the connecting circuit breaker changes from the open position to the closed position, the three-phase voltage value at the time when the connecting circuit breaker changes is recorded as the second voltage value, and at the same time, the phase value of the three-phase current at the time when the connecting circuit breaker changes is recorded as the second phase value;

[0152] When the first voltage value is less than the voltage threshold, and the second voltage value is greater than the voltage threshold, and the difference between the second phase value and the first phase value is within the first phase threshold range, the FTU current reference direction inversion operation is performed.

[0153] In some embodiments of the present application, the execution module 74 is used for, when the load transfer mode is the fault transfer mode, the control strategy includes a fault control strategy corresponding to the fault transfer mode, and the fault control strategy is used for, when a fault transfer load occurs in the distribution line, controlling the FTU current reference direction to operate in reverse phase;

[0154] Based on the first phase value, the FTU current reference direction is controlled to reversely operate by executing a control strategy corresponding to the load transfer mode, and further comprising:

[0155] The record starts from the time when the upstream circuit breaker is detected to change from the closed position to the open position, and ends when the connecting circuit breaker is detected to change from the open position to the closed position. The elapsed time is the first transfer time;

[0156] When the first transfer time is within the first time threshold range, the first voltage value is less than the voltage threshold, the second voltage value is greater than the voltage threshold, and the difference between the second phase value and the first phase value is within the first phase threshold range, the FTU current reference direction inversion operation is performed.

[0157] In some embodiments of the present application, the execution module 74 is used for when the load transfer mode is the power outage transfer mode, the control strategy includes a power outage control strategy corresponding to the power outage transfer mode, and the power outage control strategy is used for when a power outage occurs in the distribution line to transfer the load, to control the FTU current reference direction to reverse the operation;

[0158] Based on the first phase value, the FTU current reference direction is controlled to be reversed by executing a control strategy corresponding to the load transfer mode, including:

[0159] When the opening information of the upstream circuit breaker or the connecting circuit breaker is detected first, the three-phase voltage value at the moment of the opening change is recorded as the third voltage value;

[0160] When the closing information of the tie circuit breaker or the upstream circuit breaker is detected later, the three-phase voltage value at the moment of closing change is recorded as a fourth voltage value, and at the same time, the phase value of the three-phase current at the moment of closing change is recorded as a third phase value;

[0161] When the third voltage value is less than the voltage threshold, and the fourth voltage value is greater than the voltage threshold, and the difference between the third phase value and the first phase value is within the first phase threshold range, the FTU current reference direction inversion operation is performed.

[0162] In some embodiments of the present application, the execution module 74 is used for when the load transfer mode is the power outage transfer mode, the control strategy includes a power outage control strategy corresponding to the power outage transfer mode, and the power outage control strategy is used for when a power outage occurs in the distribution line to transfer the load, to control the FTU current reference direction to reverse the operation;

[0163] Based on the first phase value, the FTU current reference direction is controlled to reversely operate by executing a control strategy corresponding to the load transfer mode, and further comprising:

[0164] The recording starts from when the opening information is detected and ends when the closing information is detected. The elapsed time is the second transfer time.

[0165] When the second transfer time is within the second time threshold range, the third voltage value is less than the voltage threshold, the fourth voltage value is greater than the voltage threshold, and the difference between the third phase value and the first phase value is within the first phase threshold range, the FTU current reference direction inversion operation is performed.

[0166] In some embodiments of the present application, the execution module 74 is used for, when the load transfer mode is the operation transfer mode, the control strategy includes an operation control strategy corresponding to the operation transfer mode, and the operation control strategy is used for, when the distribution line has a closing and unclosing operation to transfer the load, controlling the FTU current reference direction to reverse the phase operation;

[0167] Based on the first phase value, the FTU current reference direction is controlled to be reversed by executing a control strategy corresponding to the load transfer mode, including:

[0168] When the closing information of the upstream circuit breaker or the connecting circuit breaker is detected first, and the opening information of the connecting circuit breaker or the upstream circuit breaker is detected later, the phase value of the three-phase current at the moment after the opening change is recorded as the fourth phase value;

[0169] When the difference between the fourth phase value and the first phase value is within the first phase threshold range, an FTU current reference direction inversion operation is performed.

[0170] In some embodiments of the present application, the execution module 74 is used for, when the load transfer mode is the operation transfer mode, the control strategy includes an operation control strategy corresponding to the operation transfer mode, and the operation control strategy is used for, when the distribution line has a closing and unclosing operation to transfer the load, controlling the FTU current reference direction to reverse the phase operation;

[0171] Based on the first phase value, the FTU current reference direction is controlled to reversely operate by executing a control strategy corresponding to the load transfer mode, and further comprising:

[0172] The recording starts from when the closing information is detected and ends when the opening information is detected. The elapsed time is the third transfer time.

[0173] When the third transfer time is within the third time threshold range and the difference between the fourth phase value and the first phase value is within the first phase threshold range, the FTU current reference direction inversion operation is performed.

[0174] The third aspect of the present application provides a FTU current direction control system, including:

[0175] The FTU unit is configured to collect line information of the distribution line, the line information at least including: three-phase voltage value, three-phase current value, fault identification, and phase difference value of power supplies on both sides of the tie circuit breaker;

[0176] A controller is configured to execute a FTU current direction control method in the first aspect or its various implementations.

[0177] The controller can be a mobile phone, tablet computer, desktop computer, laptop computer, server, industrial computer, single-chip microcomputer, PLC (Programmable Logic Controller), DSP (digital signal processor), FPGA (Field Programmable Gate Array), ASIC (Application-specific integrated circuit) and other devices with storage and computing functions, and the embodiments of the present application do not limit this.

[0178] Since the FTU current direction control system provided in this embodiment has the FTU current direction control method provided in any of the above embodiments, the FTU current direction control system has all the beneficial effects of the FTU current direction control method provided in any of the above embodiments, which will not be repeated here.

[0179] It should be noted that the terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0180] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "exemplary embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0181] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A FTU current direction control method, characterized in that: include: Acquire line information of the power distribution line, the line information including at least: three-phase voltage value, three-phase current value, fault mark, and phase difference value of power supplies on both sides of the tie circuit breaker; Calculating phase values ​​of the three-phase current based on the three-phase voltage values ​​and the three-phase current values; Record the phase value of the three-phase current at the current moment as the first phase value; Based on the fault identifier and the phase difference between the power supplies on both sides of the tie circuit breaker, a load transfer mode is determined, wherein the load transfer mode includes: a fault transfer mode, a power failure transfer mode, and an operation transfer mode; Based on the first phase value, the FTU current reference direction is controlled to operate in reverse by executing the control strategy corresponding to the load transfer mode.

2. A FTU current direction control method as claimed in claim 1, characterized in that: Based on the fault identifier and the phase difference between the power supplies on both sides of the tie circuit breaker, the step of determining the load transfer mode includes: Based on the fault identifier, determining whether there is fault information; If yes, the load transfer mode is a failover mode; If not, determine whether the phase difference between the power supplies on both sides of the tie circuit breaker is 0°; When the phase difference between the power supplies on both sides of the tie circuit breaker is 0°, the load transfer mode is the operation transfer mode; When the phase difference between the power supplies on both sides of the tie circuit breaker is not 0°, the load transfer mode is a power failure transfer mode.

3. A FTU current direction control method as claimed in claim 1, characterized in that: When the load transfer mode is a fault transfer mode, the control strategy includes a fault control strategy corresponding to the fault transfer mode, and the fault control strategy is used to control the FTU current reference direction to operate in reverse when a fault transfer load occurs on the distribution line; Based on the first phase value, by executing the control strategy corresponding to the load transfer mode, controlling the FTU current reference direction to reverse the operation, including: When it is first detected that the upstream circuit breaker changes from the closed position to the open position, the three-phase voltage value at the moment after the upstream circuit breaker changes is recorded as a first voltage value; When it is detected that the connecting circuit breaker changes from the open position to the closed position, the three-phase voltage value at the time when the connecting circuit breaker changes is recorded as a second voltage value, and at the same time, the phase value of the three-phase current at the time when the connecting circuit breaker changes is recorded as a second phase value; When the first voltage value is less than a voltage threshold, and the second voltage value is greater than a voltage threshold, and the difference between the second phase value and the first phase value is within a first phase threshold range, an FTU current reference direction inversion operation is performed.

4. A FTU current direction control method as claimed in claim 3, characterized in that: When the load transfer mode is a fault transfer mode, the control strategy includes a fault control strategy corresponding to the fault transfer mode, and the fault control strategy is used to control the FTU current reference direction to operate in reverse when a fault transfer load occurs on the distribution line; Based on the first phase value, by executing the control strategy corresponding to the load transfer mode, controlling the FTU current reference direction to reverse the operation, further comprising: The recording starts from when the upstream circuit breaker is detected to be changed from the closed position to the open position and ends when the connecting circuit breaker is detected to be changed from the open position to the closed position, and the elapsed time is the first transfer time; When the first transfer time is within a first time threshold range, and the first voltage value is less than a voltage threshold, and the second voltage value is greater than a voltage threshold, and the difference between the second phase value and the first phase value is within a first phase threshold range, an FTU current reference direction inversion operation is performed.

5. A FTU current direction control method as claimed in claim 1, characterized in that: When the load transfer mode is a power outage transfer mode, the control strategy includes a power outage control strategy corresponding to the power outage transfer mode, and the power outage control strategy is used to control the FTU current reference direction to reverse operation when a power outage occurs on the distribution line to transfer the load; Based on the first phase value, by executing the control strategy corresponding to the load transfer mode, controlling the FTU current reference direction to reverse the operation, including: When the opening information of the upstream circuit breaker or the connecting circuit breaker is detected first, the three-phase voltage value at the moment of the opening change is recorded as the third voltage value; When the closing information of the tie circuit breaker or the upstream circuit breaker is detected later, the three-phase voltage value at the moment after the closing change is recorded as a fourth voltage value, and at the same time, the phase value of the three-phase current at the moment after the closing change is recorded as a third phase value; When the third voltage value is less than the voltage threshold, and the fourth voltage value is greater than the voltage threshold, and the difference between the third phase value and the first phase value is within the first phase threshold range, an FTU current reference direction inversion operation is performed.

6. A FTU current direction control method as claimed in claim 5, characterized in that: When the load transfer mode is a power outage transfer mode, the control strategy includes a power outage control strategy corresponding to the power outage transfer mode, and the power outage control strategy is used to control the FTU current reference direction to reverse operation when a power outage occurs on the distribution line to transfer the load; Based on the first phase value, by executing the control strategy corresponding to the load transfer mode, controlling the FTU current reference direction to reverse the operation, further comprising: The recording starts from when the opening information is detected and ends when the closing information is detected, and the elapsed time is the second transfer time; When the second transfer time is within a second time threshold range, and the third voltage value is less than a voltage threshold, and the fourth voltage value is greater than a voltage threshold, and the difference between the third phase value and the first phase value is within a first phase threshold range, an FTU current reference direction inversion operation is performed.

7. A FTU current direction control method as claimed in claim 1, characterized in that: When the load transfer mode is an operation transfer mode, the control strategy includes an operation control strategy corresponding to the operation transfer mode, and the operation control strategy is used to control the FTU current reference direction to reverse the phase when the distribution line has a closing and opening operation to transfer the load; Based on the first phase value, by executing the control strategy corresponding to the load transfer mode, controlling the FTU current reference direction to reverse the operation, including: When the closing information of the upstream circuit breaker or the connecting circuit breaker is detected first, and the opening information of the connecting circuit breaker or the upstream circuit breaker is detected later, the phase value of the three-phase current at the moment of the opening change is recorded as a fourth phase value; When the difference between the fourth phase value and the first phase value is within a first phase threshold range, an FTU current reference direction inversion operation is performed.

8. A FTU current direction control method as claimed in claim 7, characterized in that: When the load transfer mode is an operation transfer mode, the control strategy includes an operation control strategy corresponding to the operation transfer mode, and the operation control strategy is used to control the FTU current reference direction to reverse the phase when the distribution line has a closing and opening operation to transfer the load; Based on the first phase value, by executing the control strategy corresponding to the load transfer mode, controlling the FTU current reference direction to reverse the operation, further comprising: The recording starts from when the closing information is detected and ends when the opening information is detected, and the elapsed time is the third transfer time; When the third transfer time is within a third time threshold range and the difference between the fourth phase value and the first phase value is within a first phase threshold range, an FTU current reference direction inversion operation is performed.

9. A FTU current direction control device, characterized in that: include: An acquisition module is used to acquire line information of a distribution line, wherein the line information includes at least: three-phase voltage value, three-phase current value, fault identification, and phase difference value of power supplies on both sides of a tie circuit breaker; A calculation module, configured to calculate a phase value of the three-phase current based on the three-phase voltage value and the three-phase current value; and record the phase value of the three-phase current at a current moment as a first phase value; A judgment module, configured to judge a load transfer mode based on the fault identifier and a phase difference between power supplies on both sides of the tie circuit breaker, wherein the load transfer mode includes: a fault transfer mode, a power failure transfer mode, and an operation transfer mode; An execution module is used to control the FTU current reference direction to reverse operation based on the first phase value by executing a control strategy corresponding to the load transfer mode.

10. A FTU current direction control system, characterized in that: include: The FTU unit is configured to collect line information of the distribution line, wherein the line information includes at least: three-phase voltage value, three-phase current value, fault identification, and phase difference value of power supplies on both sides of the tie circuit breaker; A controller is configured to execute a FTU current direction control method according to any one of claims 1-8.

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