A method and system for automatic switching of backup power supply based on double voltage criterion

Abstract

The application discloses a kind of based on voltage double criterion's reserve power automatic switching control method and system, it is applied to transformer substation, method includes: reserve self-admission safety interlocking device is gathered corresponding low-voltage side bus voltage signal, protection action signal and switch signal, according to the voltage signal of the low-voltage side bus, protection action signal and switch signal are judged, generate logic state signal and send to other reserve self-admission safety interlocking device in the transformer substation and other transformer substation corresponding reserve self-admission safety interlocking device;The reserve self-admission safety interlocking device is according to the voltage signal of itself, protection action signal, switch signal and received logic state signal carries out comprehensive logic judgment, determines the reserve self-admission operation mode under different power supply mode;The method can guarantee the reliability of power supply.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrical technology, and in particular to a backup power automatic switching control method and system based on voltage double criteria. BACKGROUND

[0002] The backup power automatic switching device is an automatic device installed in the power system to improve the reliability of power supply, which plays an important role in improving the reliability of load power supply and ensuring continuous power supply. When one working voltage fails to supply power, the device quickly cuts off the faulty voltage line and puts another normal working power supply into operation. At present, the backup power automatic switching device (hereinafter referred to as "backup automatic switching device") and the safety and stability interconnection device are configured separately, and the safety and stability interconnection device is determined by the action logic of the external input signal of the backup automatic switching device. Due to the large number of distributed power sources connected, the actual working current of the main transformer secondary switchgear is often less than 5% of the rated working current (randomness exists), which leads to the phenomenon of no-flow lockout failure.

[0003] At present, the backup power automatic switching device is applied to the 35(10) kilovolt bus of the low-voltage side of the substation, and one set of backup automatic switching device (including incoming line backup automatic switching function and bridge backup automatic switching function) is generally configured for the low-voltage side 2-section bus. Two or more sets of backup automatic switching devices need to be configured for three main transformers, and some functions are locked out. For example, a substation has three main transformers, 220 / 110 / 35 kilovolts, and the low-voltage side 3-section bus is single bus three-section wiring. One set of backup automatic switching device is configured for each of the low-voltage sides of the No. 1 and No. 2 main transformers and the No. 2 and No. 3 main transformers. In the normal operation mode, the No. 1, No. 2, and No. 3 main transformers respectively carry the 35 kilovolt I, II, and III section buses. When the upper power supply of the No. 2 main transformer fails, the two sets of backup automatic switching devices start the bridge backup automatic switching function, and the 35 kilovolt I and III section buses compete or abnormally form a ring. Patent document CN110323821A discloses a control method for backup automatic switching of a multi-section ring network switchgear, which includes a plurality of section buses arranged in sequence. Two ends of each section bus on one side are respectively connected to a circuit breaker, and the other side is connected to a main transformer through an incoming line circuit breaker. The two circuit breakers near the adjacent two section buses are short-circuited, and the remaining two circuit breakers of the first and last two section buses are short-circuited. The multiple circuit breakers on the multi-section bus form a ring connection. By closing the two short-circuited circuit breakers on the left side of the voltage failure section bus or closing the two short-circuited circuit breakers on the right side, the series connection between the voltage failure section bus and the left section bus or the series connection between the voltage failure section bus and the right section bus is realized, thereby realizing the backup automatic switching operation between the multi-section buses. However, this method needs to determine the operation mode of the backup automatic switching device by opening and closing, detecting voltage, and has low automation degree.

[0004] In addition, in the original backup automatic switching action logic, only incoming line backup automatic switching function and bridge backup automatic switching function exist, and when a new bus of a substation is expanded, original backup power automatic switching device needs to be debugged synchronously with the stop of a previously built bus to be debugged (because two buses are configured with one set of backup power automatic switching device, the device is debugged with the stop of the two buses), which causes external power outage, reduces power supply reliability and has a great influence. SUMMARY

[0005] The application provides a backup power automatic switching control method and system based on voltage double criteria, which can improve power supply reliability.

[0006] A backup power automatic switching control method based on voltage double criteria is applied to a substation, the substation comprises at least two main transformers, the at least two main transformers adopt single-bus sectionalization wiring, each low-voltage side bus is provided with a tie line for tie-in with a low-voltage side bus of another substation, and each low-voltage side bus is configured with a backup automatic switching safety tie-in device; the method comprises the following steps:

[0007] The backup automatic switching safety tie-in device collects voltage signals, protection action signals and switch signals of the corresponding low-voltage side bus, judges according to the voltage signals, protection action signals and switch signals of the low-voltage side bus, generates a logic state signal and sends the logic state signal to other backup automatic switching safety tie-in devices of the substation and corresponding backup automatic switching safety tie-in devices of other substations;

[0008] The backup automatic switching safety tie-in device comprehensively judges according to the voltage signals, protection action signals, switch signals and received logic state signals of the backup automatic switching safety tie-in device, and determines backup automatic switching operation modes under different power supply modes.

[0009] Further, the protection action signals comprise main transformer protection action signals and tie line protection action signals, the switch signals comprise main transformer secondary total circuit breaker manual tripping signals, tie line circuit breaker manual tripping signals and sectionalization circuit breaker position states, and the logic state signal comprises a device locking mark.

[0010] The backup automatic switching safety tie-in device judges according to the protection action signals and switch signals, generates a logic state signal, and the judgment comprises the following steps:

[0011] The backup automatic switching safety tie-in device judges whether main transformer protection action occurs according to the main transformer protection action signals, and the backup automatic switching safety tie-in device is locked when the main transformer protection action occurs.

[0012] The backup automatic switching safety tie-in device judges whether tie line protection action occurs according to the tie line protection action signals, and the backup automatic switching safety tie-in device is locked when the tie line protection action occurs and the low-voltage side bus of the present section fails.

[0013] The backup power automatic switching safety device judges whether the main transformer secondary total circuit breaker manual opening and the tie line circuit breaker manual opening occur according to the main transformer secondary total circuit breaker manual opening signal and the tie line circuit breaker manual opening signal respectively, and is locked when the main transformer secondary total circuit breaker manual opening or the tie line circuit breaker manual opening occurs.

[0014] After the backup power automatic switching safety device is locked, the device locking flag is set to 1, and if the backup power automatic switching safety device is not locked, the device locking flag is 0.

[0015] Further, the logic state signal further includes a bus voltage logic signal.

[0016] The backup power automatic switching safety device judges according to the voltage signal of the low-voltage side bus to generate a logic state signal, including:

[0017] The low-voltage side bus live indicator signal is collected, and consistency verification is performed on the low-voltage side bus live indicator signal and the voltage signal: when the voltage signal and the low-voltage side bus live indicator signal are both normal, a bus voltage logic signal 1 is generated, and when the voltage signal and the low-voltage side bus live indicator signal are both abnormal, a bus voltage logic signal 0 is generated.

[0018] The method further includes:

[0019] When the voltage signal is normal and the low-voltage side bus live indicator signal is abnormal, or the voltage signal is abnormal and the low-voltage side bus live indicator signal is normal, an alarm signal is generated.

[0020] Further, with left and right as logical relative positions, each low-voltage side bus includes a left adjacent low-voltage side bus and a right adjacent low-voltage side bus, and is respectively provided with a left adjacent sectional circuit breaker and a right adjacent sectional circuit breaker.

[0021] The switch signal includes a main transformer secondary total circuit breaker signal, a tie line circuit breaker signal, a left adjacent sectional circuit breaker signal, a right adjacent sectional circuit breaker signal, a sectional backup power automatic switching function plunger position signal, a tie line backup power automatic switching function plunger position signal, and an incoming line backup power automatic switching function plunger position signal.

[0022] The logic state signal further includes a tie line power supply mode signal.

[0023] The backup power automatic switching safety device judges according to the switch signal to generate a logic state signal, including:

[0024] The backup power automatic switching safety cut-off device judges whether the low-voltage side bus of the section is powered by the tie line according to the tie line circuit breaker signal. If the tie line circuit breaker signal shows that the tie line circuit breaker is in the closed position, it is determined that the low-voltage side bus of the section is powered by the tie line, the tie line power supply mode signal is set to 1, otherwise, the tie line power supply mode signal is set to 0.

[0025] Further, the backup power automatic switching safety cut-off device comprehensively judges the backup power automatic switching operation mode under different power supply modes according to the voltage signal, protection action signal, switch signal and received logic state signal of the backup power automatic switching safety cut-off device itself, including:

[0026] Under the main transformer power supply mode, if the main transformer secondary total circuit breaker signal corresponding to the low-voltage side bus of the section shows that the main transformer secondary total circuit breaker is in the closed position, the tie line circuit breaker signal shows that the tie line circuit breaker is in the open position, the left adjacent section circuit breaker signal and the right adjacent section circuit breaker signal show that the left adjacent section circuit breaker and the right adjacent section circuit breaker are both in the tripped position, the section backup power automatic switching function plunger position signal shows that the plunger of the section backup power automatic switching function is in the input position, the device locking flags of the backup power automatic switching safety cut-off devices corresponding to the low-voltage side bus of the section, the left adjacent low-voltage side bus and the right adjacent low-voltage side bus are all 0, the bus voltage logic signals of the low-voltage side bus of the section and the right adjacent low-voltage side bus are both 1, the tie line power supply mode signal corresponding to the right adjacent low-voltage side bus is 0, and the bus voltage logic signal of the left adjacent low-voltage side bus is 0 or the bus voltage logic signal of the left adjacent low-voltage side bus is 1 and the right tie line priority logic signal is 1, it is determined to adopt the right tie section backup power automatic switching operation mode.

[0027] Under the main transformer power supply mode, if the main transformer secondary total circuit breaker signal corresponding to the low-voltage side bus of the section shows that the main transformer secondary total circuit breaker is in the closed position, the tie line circuit breaker signal shows that the tie line circuit breaker is in the open position, the left adjacent section circuit breaker signal and the right adjacent section circuit breaker signal show that the left adjacent section circuit breaker and the right adjacent section circuit breaker are both in the tripped position, the section backup power automatic switching function plunger position signal shows that the plunger of the section backup power automatic switching function is in the input position, the device locking flags of the backup power automatic switching safety cut-off devices corresponding to the low-voltage side bus of the section, the left adjacent low-voltage side bus and the right adjacent low-voltage side bus are all 0, the bus voltage logic signals of the low-voltage side bus of the section and the left adjacent low-voltage side bus are both 1, the tie line power supply mode signal corresponding to the left adjacent low-voltage side bus is 0, and the bus voltage logic signal of the right adjacent low-voltage side bus is 0 or the bus voltage logic signal of the right adjacent low-voltage side bus is 1 and the left tie line priority logic signal is 1, it is determined to adopt the left tie section backup power automatic switching operation mode.

[0028] Further, the left tie line priority logic signal and the right tie line priority logic signal are externally inputted.

[0029] In the right-association segment backup automatic switching operation mode, the right-adjacent segment circuit breaker is controlled to be closed.

[0030] In the left-association segment backup automatic switching operation mode, the left-adjacent segment circuit breaker is controlled to be closed.

[0031] Further, the backup automatic switching safety interlocking device determines the backup automatic switching operation mode under different power supply modes according to the voltage signal, the protection action signal, the switch signal and the received logic state signal, and the determination includes:

[0032] In the main transformer power supply mode, if the left-adjacent segment circuit breaker signal and the right-adjacent segment circuit breaker signal show that the left-adjacent segment circuit breaker and the right-adjacent segment circuit breaker are both in the open position, the main transformer secondary circuit breaker signal corresponding to the low-voltage side bus shows that the main transformer secondary circuit breaker is in the closed position, the tie-line circuit breaker signal corresponding to the low-voltage side bus shows that the tie-line circuit breaker of the low-voltage side bus is in the open position, the pressure plate position signal of the tie-line backup automatic switching function shows that the pressure plate of the tie-line backup automatic switching function is in the input position, the device locking flags of the backup automatic switching safety interlocking devices corresponding to the low-voltage side bus and the low-voltage side bus of the tie-line are both 0, and the bus voltage logic signals of the low-voltage side bus and the low-voltage side bus of the tie-line are both 1, the tie-line backup automatic switching operation mode is determined to be adopted.

[0033] In the tie-line backup automatic switching operation mode, the low-voltage side bus and the corresponding tie-line circuit breaker are controlled to be closed.

[0034] Further, the backup automatic switching safety interlocking device determines the backup automatic switching operation mode under different power supply modes according to the voltage signal, the protection action signal, the switch signal and the received logic state signal, and the determination includes:

[0035] In the main transformer power supply mode, if the main transformer secondary circuit breaker signal corresponding to the low-voltage side bus shows that the main transformer secondary circuit breaker is in the closed position, the tie-line circuit breaker signal shows that the tie-line circuit breaker is in the open position, the right-adjacent segment circuit breaker signal shows that the right-adjacent segment circuit breaker is in the closed position, the pressure plate position signal of the incoming line backup automatic switching function shows that the pressure plate of the incoming line backup automatic switching function is in the input position, the left-adjacent segment circuit breaker signal shows that the left-adjacent segment circuit breaker is in the open position or the left-adjacent segment circuit breaker is in the closed position and the right-tie-line priority logic signal is 1, the device locking flags of the backup automatic switching safety interlocking devices corresponding to the low-voltage side bus, the left-adjacent low-voltage side bus and the right-adjacent low-voltage side bus are all 0, and the bus voltage logic signals of the low-voltage side bus and the right-adjacent low-voltage side bus are both 1, the right-incoming line backup automatic switching operation mode is adopted.

[0036] In the main transformer power supply mode, if the main transformer secondary total circuit breaker signal corresponding to the low-voltage side bus of the section shows that the main transformer secondary total circuit breaker is in the closed position, the tie line circuit breaker signal shows that the tie line circuit breaker is in the open position, the left adjacent section circuit breaker signal shows that the left adjacent section circuit breaker is in the closed position, the position signal of the pressure plate of the incoming line backup power supply function shows that the pressure plate of the incoming line backup power supply function is in the input position, the right adjacent section circuit breaker signal shows that the right adjacent section circuit breaker is in the open position or the right adjacent section circuit breaker is in the closed position and the left tie priority logic signal is 1, the device locking signs of the backup power supply safety interlocking device corresponding to the low-voltage side bus of the section, the left adjacent low-voltage side bus and the right adjacent low-voltage side bus are all 0, and the bus voltage logic signals of the low-voltage side bus of the section and the left adjacent low-voltage side bus are both 1, the left incoming line backup power supply operation mode is adopted.

[0037] Further, the backup power supply safety interlocking device comprehensively judges according to the voltage signal, the protection action signal, the switch signal and the received logic state signal, determines the backup power supply operation mode in different power supply modes, including:

[0038] In the non-main transformer power supply mode, the right adjacent section circuit breaker signal shows that the right adjacent section circuit breaker is in the closed position, the main transformer secondary total circuit breaker signal corresponding to the low-voltage side bus of the section shows that the main transformer secondary total circuit breaker is in the tripped position, the tie line circuit breaker signal corresponding to the low-voltage side bus of the section shows that the tie line circuit breaker is in the open position, the position signal of the pressure plate of the incoming line backup power supply function shows that the pressure plate of the incoming line backup power supply function is in the input position, the device locking signs of the backup power supply safety interlocking device corresponding to the low-voltage side bus of the section, the left adjacent low-voltage side bus and the right adjacent low-voltage side bus are all 0, and the bus voltage logic signals of the low-voltage side bus of the section and the right adjacent low-voltage side bus are both 1, the main transformer backup power supply operation mode with the right adjacent section circuit breaker in the closed position is adopted.

[0039] In the non-main transformer power supply mode, the left adjacent section circuit breaker signal shows that the left adjacent section circuit breaker is in the closed position, the main transformer secondary total circuit breaker signal corresponding to the low-voltage side bus of the section shows that the main transformer secondary total circuit breaker is in the tripped position, the tie line circuit breaker signal corresponding to the low-voltage side bus of the section shows that the tie line circuit breaker is in the open position, the position signal of the pressure plate of the incoming line backup power supply function shows that the pressure plate of the incoming line backup power supply function is in the input position, the device locking signs of the backup power supply safety interlocking device corresponding to the low-voltage side bus of the section, the left adjacent low-voltage side bus and the right adjacent low-voltage side bus are all 0, and the bus voltage logic signals of the low-voltage side bus of the section and the left adjacent low-voltage side bus are both 1, the main transformer backup power supply operation mode with the left adjacent section circuit breaker in the closed position is adopted.

[0040] In the non-main transformer power supply mode, the left adjacent sectionalizer circuit breaker signal and the right adjacent sectionalizer circuit breaker signal show that the left adjacent sectionalizer circuit breaker and the right adjacent sectionalizer circuit breaker are in the section position, the main transformer secondary total circuit breaker signal corresponding to the low-voltage side bus of the section shows that the main transformer secondary total circuit breaker is in the section position, the tie line circuit breaker signal corresponding to the low-voltage side bus of the section shows that the tie line circuit breaker is in the post-position, the device locking signs of the low-voltage side bus backup power automatic switching safety interlocking device corresponding to the low-voltage side bus of the section and the tie line are both 0, the tie line backup power automatic switching function platen position signal shows that the platen of the tie line backup power automatic switching function is in the input position, and the bus voltage logic signals of the low-voltage side bus corresponding to the low-voltage side bus of the section and the tie line are both 1, so the tie line main transformer backup power automatic switching operation mode is adopted.

[0041] A backup power automatic switching control system based on voltage double criteria, comprising at least two transformer substations, the transformer substations comprising at least two main transformers, the at least two main transformers adopting single bus section wiring, each low-voltage side bus being provided with a tie line for tie-in with low-voltage side buses of other transformer substations, and each low-voltage side bus being configured with a backup power automatic switching safety interlocking device;

[0042] The backup power automatic switching safety interlocking device is used to collect voltage signals, protection action signals and switch signals of the corresponding low-voltage side bus, judge according to the voltage signals, protection action signals and switch signals of the low-voltage side bus, generate logic state signals and send to other backup power automatic switching safety interlocking devices of the transformer substation and corresponding backup power automatic switching safety interlocking devices of other transformer substations;

[0043] The backup power automatic switching safety interlocking device is also used to comprehensively logically judge according to the voltage signals, protection action signals, switch signals and received logic state signals of itself, and determine backup power automatic switching operation modes in different power supply modes.

[0044] The backup power automatic switching control method and system based on voltage double criteria provided by the application have at least the following beneficial effects:

[0045] (1) The backup power automatic switching safety interlocking device is configured for each low-voltage side bus, and adjacent backup power automatic switching safety interlocking devices can mutually signal, voltage signals, protection action signals and switch signals are used for comprehensive logical judgment, reliable, accurate and rapid outlet tripping and closing of associated circuit breakers are realized, and the power supply of the bus is rapidly restored.

[0046] (2) The existing current is abandoned as a logical judgment condition, and the voltage signal of the bus and the double criteria of the low-voltage side bus live indicator signal are used for joint judgment for the logical judgment of the bus voltage, which can effectively avoid the failure of no-flow locking;

[0047] (3) Adjacent backup automatic transfer safety interlocking devices can exchange signals and block each other to avoid competition between different devices or abnormal looping between adjacent busbars.

[0048] (4) The automatic transfer operation mode under different power supply modes is proposed, which is applicable to a variety of application scenarios and further ensures the reliability of power supply;

[0049] (5) The method proposed in this invention only involves the newly built busbar during commissioning and has no impact on the previously built busbar, which facilitates the expansion of the substation;

[0050] (6) The method proposed in this invention is applicable to the working condition of inter-substation with tie lines. Based on the original automatic transfer switch operation logic which only has the automatic transfer switch function of incoming line and automatic transfer switch function of bridge, the automatic transfer switch scheme of tie line is adopted to realize mutual backup between substations.

[0051] (7) The method provided by the present invention can prevent islanding and asynchronous closing. When any low-voltage busbar in the substation experiences temporary or permanent loss of voltage, the active line connected to that busbar can be reliably disconnected, effectively improving the reliability of the system. Attached Figure Description

[0052] Figure 1 This is a flowchart of one embodiment of the automatic switching control method for backup power supply based on dual voltage criteria provided by the present invention.

[0053] Figure 2 This is a schematic diagram of a substation embodiment in the automatic switching control method for backup power supply based on dual voltage criteria provided by the present invention.

[0054] Figure 3 This is a schematic diagram of the substation tie line in an embodiment of the automatic switching control method for backup power supply based on dual voltage criteria provided by the present invention. Detailed Implementation

[0055] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0056] refer to Figure 1 In some embodiments, a backup power automatic switching control method based on dual voltage criteria is provided, applied to a substation. The substation includes at least two main transformers, which are connected in a single busbar segmented configuration. Each low-voltage side busbar segment is connected to the low-voltage side busbars of other substations via a tie line. Each low-voltage side busbar segment is equipped with an automatic backup power transfer safety interlocking device. The method includes:

[0057] S1, the backup power supply automatic switching safety interlocking device collects the voltage signal, the protection action signal and the switch signal of the corresponding low-voltage side bus, judges according to the voltage signal, the protection action signal and the switch signal of the low-voltage side bus, generates a logic state signal and sends it to other backup power supply automatic switching safety interlocking devices in the substation and corresponding backup power supply automatic switching safety interlocking devices in other substations;

[0058] S2, the backup power supply automatic switching safety interlocking device comprehensively judges according to the voltage signal, the protection action signal, the switch signal and the received logic state signal, and determines the backup power supply automatic switching operation mode under different power supply modes.

[0059] Reference Figure 2 In the embodiment, three main transformers of a 220KV substation are taken as an example, which are No. 1 main transformer, No. 2 main transformer and No. 3 main transformer. The three main transformers adopt single-bus sectionalization wiring, each main transformer is connected with a section of low-voltage side bus, and each section of low-voltage side bus is provided with only one loop line for loop with the opposite substation. The loop line breakers on both sides of the substation are combined in principle, the normally closed breakers on the side of the feeder (without power supply) are considered, and the normally open breakers (combined and separated points) on the side of the active line are considered. Each section of low-voltage side bus is provided with a backup power supply automatic switching safety interlocking device and can interact with signals. Each main transformer is provided with a main transformer secondary total breaker 1DL, sectional breakers 3DL and 4DL are arranged between adjacent low-voltage side buses, the loop line breaker is 2DL, A1-A4, B1-B4 and C1-C4 are active lines.

[0060] The low-voltage side bus can be a 35KV bus or a 10KV bus.

[0061] In addition, the main transformer protection device of each main transformer adopts double configuration, that is, two independent main transformer protection devices are included, and the main transformer protection action signal is the protection action signal (passive hard contact point) opened by the two main transformer protection devices and combined into a signal. The main transformer protection action limitation condition is that the main transformer low-voltage side backup protection does not trip the low-voltage side sectional breaker, and only the first time limit trips the main transformer low-voltage side and the second time limit trips each side of the main transformer.

[0062] Further, the protection action signal includes a main transformer protection action signal and a loop line protection action signal, the switch signal includes a main transformer secondary total breaker manual tripping signal, a loop line breaker manual tripping signal and a sectional breaker position state, and the logic state signal includes a device locking flag.

[0063] In step S1, the backup power supply automatic switching safety interlocking device judges according to the protection action signal and the switch signal, generates a logic state signal, which includes:

[0064] S11, the backup power automatic switching safety device judges whether the main transformer protection action occurs according to the main transformer protection action signal, and is blocked when the main transformer protection action occurs;

[0065] S12, the backup power automatic switching safety device judges whether the tie line protection action occurs according to the tie line protection action signal, and is blocked when the tie line protection action occurs and the low-voltage side bus fault occurs;

[0066] S13, the backup power automatic switching safety device judges whether the main transformer secondary total circuit breaker manual tripping and the tie line circuit breaker manual tripping occur according to the main transformer secondary total circuit breaker manual tripping signal and the tie line circuit breaker manual tripping signal respectively, and is blocked when the main transformer secondary total circuit breaker manual tripping or the tie line circuit breaker manual tripping occurs;

[0067] S14, after the backup power automatic switching safety device is blocked, the device blocking flag is set to 1, and if the backup power automatic switching safety device is not blocked, the device blocking flag is 0.

[0068] Further, the logic state signal further includes a bus voltage logic signal;

[0069] In step S1, the backup power automatic switching safety device judges according to the voltage signal of the low-voltage side bus, generates a logic state signal, including:

[0070] S15, the low-voltage side bus live indicator signal is collected, and the low-voltage side bus live indicator signal and the voltage signal are consistency checked: when the voltage signal and the low-voltage side bus live indicator signal are normal, the bus voltage logic signal 1 is generated, and when the voltage signal and the low-voltage side bus live indicator signal are abnormal, the bus voltage logic signal 0 is generated.

[0071] In some embodiments, the method further includes:

[0072] When the voltage signal is normal and the low-voltage side bus live indicator signal is abnormal, or the voltage signal is abnormal and the low-voltage side bus live indicator signal is normal, an alarm signal is generated.

[0073] In the new power system, due to the current lockout condition often fails (unreliable), in order to ensure the accuracy and reliability of the voltage logic signal, the non-analog quantity sampling logic condition is added. In the embodiment, the voltage double criterion method is adopted: the bus voltage analog quantity direct sampling discrimination and the bus live indicator logic contact signal discrimination, and the logic consistency verification is satisfied. That is, when the three-phase voltage of the low-voltage side bus is normal and the bus live indicator has voltage: the bus voltage logic is "1"; when the three-phase voltage of the bus is zero and the bus live indicator has no voltage: the bus voltage logic is "0"; otherwise, the voltage is abnormal, and the alarm is given.

[0074] The different operation modes are specifically described as follows:

[0075] 1) Transition operation mode (loop operation mode):

[0076] The low-voltage side bus corresponding to the main transformer secondary total switch, the adjacent low-voltage side bus main transformer switch secondary total and the sectionalizer of the two low-voltage side buses are in the working closing position, and the logic is "1", that is, the low-voltage side bus corresponding to the main transformer and the adjacent main transformer are looped, and the low-voltage side bus corresponding to the low-voltage side bus and the adjacent low-voltage side bus are parallel.

[0077] The low-voltage side bus corresponding to the secondary total switch, the low-voltage side bus corresponding to the tie line circuit breaker, and the low-voltage side bus corresponding to the sectionalizer are all in the working closing position, and the logic is "1", that is, the low-voltage side bus corresponding to the main transformer and the low-voltage side bus corresponding to the adjacent main transformer are looped, and the low-voltage side bus is parallel. In principle, the tie line is put into operation, and the low-voltage side bus does not consider the parallel operation mode, that is, the tie line is only used for the low-voltage side bus load.

[0078] 2) Normal operation mode:

[0079] Main transformer power supply: the low-voltage side bus corresponding to the main transformer secondary total circuit breaker is in the working closing position, and the position logic is "1"; and the three-phase voltage of the low-voltage side bus is normal and the bus live indicator has voltage, that is, the bus voltage logic is "1". That is, the low-voltage side bus is powered by the main transformer, and the main transformer operation logic flag is charged and set to "1".

[0080] Non-main transformer power supply: the low-voltage side bus corresponding to the main transformer secondary total circuit breaker is in the working closing position, and the position logic is "0"; and the three-phase voltage of the low-voltage side bus is normal and the bus live indicator has voltage, and the bus voltage logic is "1". That is, the low-voltage side bus is not powered by the main transformer, and the main transformer operation logic flag is discharged and set to "0".

[0081] Further, taking left and right as the logical relative positions, each low-voltage side bus includes a left adjacent low-voltage side bus and a right adjacent low-voltage side bus, and is respectively provided with a left adjacent sectionalizer and a right adjacent sectionalizer.

[0082] Reference Figure 2, above left and right as a logical relative position, the low-voltage side bus corresponding to the No. 2 main transformer is left relative to the low-voltage side bus corresponding to the No. 1 main transformer; the low-voltage side bus corresponding to the No. 1 main transformer is right relative to the low-voltage side bus corresponding to the No. 2 main transformer; the low-voltage side bus corresponding to the No. 3 main transformer is left relative to the low-voltage side bus corresponding to the No. 2 main transformer; the low-voltage side bus corresponding to the No. 2 main transformer is right relative to the low-voltage side bus corresponding to the No. 3 main transformer; the low-voltage side bus corresponding to the No. 3 main transformer is right relative to the low-voltage side bus corresponding to the No. 1 main transformer; the low-voltage side bus corresponding to the No. 1 main transformer is left relative to the low-voltage side bus corresponding to the No. 3 main transformer.

[0083] Further, the switch signal includes a main transformer secondary total circuit breaker signal, a tie line circuit breaker signal, a left adjacent section circuit breaker signal, a right adjacent section circuit breaker signal, a section backup power automatic switching function plunger position signal, a tie line backup power automatic switching function plunger position signal, and an incoming line backup power automatic switching function plunger position signal.

[0084] The logic state signal further includes a tie line power supply mode signal.

[0085] In step S1, the backup power automatic switching safety interlocking device judges according to the switch signal, generates a logic state signal, and includes:

[0086] S16, the backup power automatic switching safety interlocking device judges whether the low-voltage side bus of the section is powered by the tie line according to the tie line circuit breaker signal. If the tie line circuit breaker signal shows that the tie line circuit breaker is closed, it is determined that the low-voltage side bus of the section is powered by the tie line, the tie line power supply mode signal is set to 1, otherwise, the tie line power supply mode signal is set to 0.

[0087] Further, in step S2, the backup power automatic switching safety interlocking device comprehensively judges according to the voltage signal, the protection action signal, the switch signal and the received logic state signal, determines the backup power automatic switching operation mode under different power supply modes, and includes:

[0088] In the main transformer power supply mode, if the main transformer secondary total circuit breaker corresponding to the low-voltage side bus of the section displays that the main transformer secondary total circuit breaker is in the closed position, the tie line circuit breaker displays that the tie line circuit breaker is in the open position, the left adjacent section circuit breaker signal and the right adjacent section circuit breaker signal display that the left adjacent section circuit breaker and the right adjacent section circuit breaker are in the tripped position, the position signal of the section spare power automatic switching function pressure plate displays that the section spare power automatic switching function pressure plate is in the input position, the device locking signs of the spare power automatic switching safety interlocking devices corresponding to the low-voltage side bus of the section, the left adjacent low-voltage side bus and the right adjacent low-voltage side bus are all 0, the bus voltage logic signals of the low-voltage side bus of the section and the right adjacent low-voltage side bus are both 1, the tie line power supply mode signal corresponding to the right adjacent low-voltage side bus is 0, the bus voltage logic signal of the left adjacent low-voltage side bus is 0 or the bus voltage logic signal of the left adjacent low-voltage side bus is 1 and the right tie priority logic signal is 1, it is determined that the right tie section spare power automatic switching operation mode is adopted.

[0089] The right tie priority logic signal is an external input, that is, when other conditions are met, the bus voltage logic signal of the left adjacent low-voltage side bus is 1, that is, the left adjacent low-voltage side bus also has an input condition, at this time, in order to prevent competition on both sides, the right tie priority logic signal 1 is inputted externally.

[0090] The above is the charging condition of the right tie section spare power automatic switching operation mode, and the discharging condition of the right tie section spare power automatic switching operation mode includes:

[0091] The low-voltage side bus of the section or the right adjacent low-voltage side bus meets the no-voltage condition, that is, the bus voltage logic signal of the low-voltage side bus of the section or the right adjacent low-voltage side bus is 0, and the duration is greater than the discharging time 15S; or, the left tie priority logic signal is "1"; or, the tie line power supply mode signal corresponding to the right adjacent low-voltage side bus is 1; or, the pressure plate of the section spare power automatic switching is in the exit position; the device locking sign of the spare power automatic switching safety interlocking device corresponding to the low-voltage side bus of the section, the left adjacent low-voltage side bus or the right adjacent low-voltage side bus is 1; or, during the action of the spare power automatic switching, there is a circuit breaker that refuses to trip or refuses to close; or, the tie line circuit breaker corresponding to the low-voltage side bus of the section is in the closed position; or, the right adjacent section circuit breaker is closed.

[0092] Further, the action logic of the right association sectionalizing backup power supply operation mode includes: when the right association sectionalizing backup power supply operation mode is charged, the right association sectionalizing backup power supply operation mode is started, a one-step tripping delay T1 is used to send a command to trip the main transformer sub-total circuit breaker corresponding to the low-voltage side bus of the section and a "right association sectionalizing backup power supply operation mode tripping" message. The main transformer sub-total circuit breaker command is revoked after a 100 ms delay. If the main transformer sub-total circuit breaker is not tripped within 5 s of the command, a "right association sectionalizing backup power supply operation mode circuit breaker tripping refusal" message is sent, and a "right association sectionalizing backup power supply operation mode failure" alarm is sent if the low-voltage side bus interconnection switch of the section is not tripped within 5 s (the bus interconnection switch is in the input position and the interconnection switch position is connected to the device). The "right association sectionalizing backup power supply operation mode interconnection switch tripping refusal" message and the "right association sectionalizing backup power supply operation mode failure" alarm are sent. After confirming that the main transformer sub-total circuit breaker corresponding to the low-voltage side bus of the section and the corresponding interconnection switch are tripped, a one-step closing delay T3 is used to send a command to close the right adjacent sectionalizing circuit breaker and a "right sectionalizing backup power supply operation mode closing" message. The right adjacent sectionalizing circuit breaker command is revoked after a 100 ms delay. If the right adjacent sectionalizing circuit breaker is not closed within 5 s of the command, a "right sectionalizing backup power supply operation mode circuit breaker closing refusal" message and a "right sectionalizing backup power supply operation mode failure" alarm are sent. If it is confirmed that the right adjacent sectionalizing circuit breaker is closed, a "right sectionalizing backup power supply operation mode success" message is sent.

[0093] Further, in the main transformer power supply mode, if the main transformer sub-total circuit breaker signal corresponding to the low-voltage side bus of the section indicates that the main transformer sub-total circuit breaker is in the closed position, the interconnection line circuit breaker signal indicates that the interconnection line circuit breaker is in the split position, the left adjacent sectionalizing circuit breaker signal and the right adjacent sectionalizing circuit breaker signal indicate that the left adjacent sectionalizing circuit breaker and the right adjacent sectionalizing circuit breaker are both in the tripped position, the sectionalizing backup power supply function plunger position signal indicates that the sectionalizing backup power supply function plunger is in the input position, the device locking flags of the backup power supply safety interconnection devices corresponding to the low-voltage side bus of the section, the left adjacent low-voltage side bus, and the right adjacent low-voltage side bus are all 0, the bus voltage logic signals of the low-voltage side bus of the section and the left adjacent low-voltage side bus are both 1, the interconnection line power supply mode signal corresponding to the left adjacent low-voltage side bus is 0, and the bus voltage logic signal of the right adjacent low-voltage side bus is 0 or the bus voltage logic signal of the right adjacent low-voltage side bus is 1 and the left interconnection priority logic signal is 1, it is determined to use the left association sectionalizing backup power supply operation mode.

[0094] The left interconnection priority logic signal is an external input, that is, when the other conditions are met, the bus voltage logic signal of the right adjacent low-voltage side bus is 1, that is, the right adjacent low-voltage side bus also has an input condition, at this time, in order to prevent competition on both sides, the left interconnection priority logic signal 1 is input externally.

[0095] The above is the charging condition of the left association sectionalizing backup power supply operation mode. The discharging condition of the left association sectionalizing backup power supply operation mode includes:

[0096] The low-voltage side bus of the section or the left adjacent low-voltage side bus meets the pressure-free condition, that is, the bus voltage logic signal of the low-voltage side bus of the section or the left adjacent low-voltage side bus is 0, and the duration is greater than the discharge time 15S; or, the right contact priority logic signal is "1"; or, the contact line power supply mode signal corresponding to the left adjacent low-voltage side bus is 1; the pressure plate of the sectional backup power supply is in the exit position; or, the device locking flag of the backup power supply safety interlocking device corresponding to the low-voltage side bus of the section, the left adjacent low-voltage side bus or the right adjacent low-voltage side bus is 1; during the backup power supply action, there is a circuit breaker refusal to jump or refuse to close; or, the contact line circuit breaker corresponding to the low-voltage side bus of the section is in the closed position; or, the left adjacent sectional circuit breaker is closed.

[0097] Further, the action logic of the left joint sectional backup power supply operation mode includes: after the left joint sectional backup power supply operation mode is charged, the left joint sectional backup power supply mode is started, and the main transformer secondary total circuit breaker corresponding to the low-voltage side bus of the section and the "left joint sectional backup power supply mode tripping" message are tripped after a tripping delay T1. The main transformer secondary total circuit breaker command is cancelled after a 100ms delay. If the main transformer secondary total circuit breaker is not tripped within 5s of the command, "left joint sectional backup power supply circuit breaker refusal to trip" is sent, and if the bus interlocking switch corresponding to the low-voltage side bus of the section is not tripped within 5S (the bus interlocking switch is in the input position and the interlocking switch position is connected to the device), "left joint sectional backup power supply interlocking switch refusal to trip" and "left joint sectional backup power supply failure" alarms are sent; after the main transformer secondary total circuit breaker corresponding to the low-voltage side bus of the section and the corresponding interlocking switch are tripped, the command to close the left adjacent sectional circuit breaker and the "left sectional backup power supply closing" message are sent after a closing delay T3. The left adjacent sectional circuit breaker command is cancelled after a 100ms delay. If the left adjacent sectional circuit breaker is not closed within 5s of the closing command, "left sectional backup power supply circuit breaker refusal to close" and "left sectional backup power supply failure" alarms are sent; if it is confirmed that the left adjacent sectional circuit breaker is closed, the "left sectional backup power supply success" message is sent.

[0098] Further, in step S2, the backup power supply safety interlocking device performs comprehensive logic judgment according to the voltage signal, protection action signal, switch signal and received logic state signal of itself to determine the backup power supply operation mode under different power supply modes, including:

[0099] In the main transformer power supply mode, if the left adjacent sectionalizer signal and the right adjacent sectionalizer signal show that the left adjacent sectionalizer and the right adjacent sectionalizer are both in the open position, the main transformer sub-total circuit breaker signal corresponding to the low-voltage side bus of the section shows that the main transformer sub-total circuit breaker is in the closed position, the tie line circuit breaker signal corresponding to the low-voltage side bus of the section shows that the tie line circuit breaker of the low-voltage side bus of the section is in the open position, the tie line backup power supply device position signal shows that the tie line backup power supply device is in the input position, the device locking signs of the backup power supply device safety interlocking device corresponding to the low-voltage side bus of the section and the low-voltage side bus of the tie line are both 0, and the bus voltage logic signals of the low-voltage side bus of the section and the low-voltage side bus of the tie line are both 1, it is determined that the tie line backup power supply operation mode is adopted.

[0100] The above is the charging condition of the tie line backup power supply operation mode, and the discharging condition is as follows:

[0101] The voltage of the low-voltage side bus of the section and the tie line is lower than the bus voltage setting value, and the duration is greater than the discharging time 15s; or the left adjacent sectionalizer is in the closed position; or the right adjacent sectionalizer is in the closed position; or the tie line backup power supply device position is in the exit position; or the device locking sign of the backup power supply device safety interlocking device corresponding to the low-voltage side bus of the section or the low-voltage side bus of the tie line is 1; or there is a circuit breaker that refuses to trip or refuses to close (excluding adjacent device signals) during the backup power supply action; or the main transformer sub-total circuit breaker corresponding to the low-voltage side bus of the section is opened; or the tie line circuit breaker corresponding to the bus of the section is in the closed position.

[0102] In the tie line backup power supply operation mode, the low-voltage side bus of the section and the corresponding tie line circuit breaker are controlled to be closed. The specific action logic includes: after the tie line backup power supply operation charging is completed, the tie line backup power supply operation mode is started, the main transformer sub-total circuit breaker corresponding to the low-voltage side bus of the section and the "tie line backup power supply mode tripping" message are tripped after a delay T1+ΔT. The command to trip the main transformer sub-total circuit breaker is cancelled after a delay of 100 milliseconds. If the main transformer sub-total circuit breaker is not tripped within 5s of the command, the "tie line incoming line backup 1DL refuses to trip" is sent, and if the low-voltage side bus interlocking switch of the section is not tripped within 5s (the bus interlocking switch is in the input position and the position of the interlocking switch is connected to the device), the "tie line backup interlocking switch refuses to trip" and "tie line backup fails" alarms are sent; after confirming that the main transformer sub-total circuit breaker and the corresponding interlocking switch are tripped, the command to close the tie line circuit breaker corresponding to the bus of the section and the "tie line backup power supply mode closing" message are sent after a delay T2+ΔT and the left adjacent sectionalizer and the right adjacent sectionalizer are both in the open position. The command to close the tie line circuit breaker is cancelled after a delay of 100 milliseconds. If the tie line circuit breaker is not closed within 5s of the command, the "tie line backup 2DL refuses to close" and "tie line backup fails" alarms are sent; if it is confirmed that the tie line circuit breaker is closed, the "tie line backup succeeds" message is sent.

[0103] Because the tie line backup power supply has the lowest priority, compared with the incoming line backup power supply and the sectional backup power supply, a delay time ΔT (generally 0.3S-0.5S) is added.

[0104] Further, the backup power supply safety interlocking device comprehensively judges according to the voltage signal, the protection action signal, the switch signal and the received logic state signal, determines the backup power supply operation mode under different power supply modes, and includes:

[0105] Under the main transformer power supply mode, if the main transformer secondary circuit breaker signal corresponding to the low-voltage side bus of the section shows that the main transformer secondary circuit breaker is in the closed position, the tie line circuit breaker signal shows that the tie line circuit breaker is in the open position, the right adjacent sectional circuit breaker signal shows that the right adjacent sectional circuit breaker is in the closed position, the incoming line backup power supply function plunger position signal shows that the plunger of the incoming line backup power supply function is in the input position, the left adjacent sectional circuit breaker signal shows that the left adjacent sectional circuit breaker is in the open position or the left adjacent sectional circuit breaker is in the closed position and the right tie line priority logic signal is 1, the device locking flags of the backup power supply safety interlocking devices corresponding to the low-voltage side bus of the section, the left adjacent low-voltage side bus and the right adjacent low-voltage side bus are all 0, and the bus voltage logic signals of the low-voltage side bus of the section and the right adjacent low-voltage side bus are both 1, the right incoming line backup power supply operation mode is adopted.

[0106] The charging condition of the right incoming line backup power supply operation mode is described above, and the discharging condition is that the bus voltage logic signals of the low-voltage side bus of the section and the right adjacent bus are both 0 and the duration is greater than the discharging time 15S; or the plunger of the incoming line backup power supply function is in the exit position; or the device locking flag of the backup power supply safety interlocking device corresponding to the low-voltage side bus of the section, the left adjacent low-voltage side bus or the right adjacent low-voltage side bus is 1; or there is a circuit breaker refusal to trip or refuse to close during the backup power supply action; or the tie line circuit breaker corresponding to the low-voltage side bus of the section is in the closed position; or the right adjacent sectional circuit breaker is in the open position; or the left tie line priority logic signal is 1.

[0107] Further, the action logic of the right incoming line backup power supply operation mode includes: when the right incoming line backup power supply mode is charged, the right incoming line backup power supply mode is started, and the corresponding main transformer secondary total circuit breaker of the low-voltage side bus and the "right incoming line backup power supply mode tripping" message are tripped after a one-time tripping delay T1. The main transformer secondary total circuit breaker command is cancelled after a 100 ms delay. If the main transformer secondary total circuit breaker is not tripped within 5s of the command, "right incoming line backup power supply 1DL refuses to trip" is sent, and if the low-voltage side bus interconnection switch is not tripped within 5s (the bus interconnection switch is connected to the input device and the interconnection switch position is connected to the device), "right incoming line backup power supply interconnection switch refuses to trip" and "right incoming line backup power supply failure" alarms are sent; after confirming that the main transformer secondary total circuit breaker and the corresponding interconnection switch are tripped, a "right incoming line backup power supply tripping and interconnection switch success" signal is sent to the right adjacent backup power supply safety interconnection device (note: this device is defined as the "right interconnection switch out" signal, and the opposite device is defined as the "left interconnection switch in" signal). Then, the low-voltage side bus maintains the current state, and after a delay T2, if the three-phase bus voltage is normal, "right incoming line backup power supply success" message is sent; otherwise, "right incoming line backup power supply failure" message is sent.

[0108] Further, in the main transformer power supply mode, if the main transformer secondary total circuit breaker signal of the low-voltage side bus indicates that the main transformer secondary total circuit breaker is in the closed position, the interconnection line circuit breaker signal indicates that the interconnection line circuit breaker is in the open position, the left adjacent section circuit breaker signal indicates that the left adjacent section circuit breaker is in the closed position, the position signal of the incoming line backup power supply function plunger indicates that the plunger of the incoming line backup power supply function is in the input position, the right adjacent section circuit breaker signal indicates that the right adjacent section circuit breaker is in the open position or the right adjacent section circuit breaker is in the closed position and the left interconnection priority logic signal is 1, and the device lockout flags of the backup power supply safety interconnection devices corresponding to the low-voltage side bus, the left adjacent low-voltage side bus and the right adjacent low-voltage side bus are all 0, and the bus voltage logic signals of the low-voltage side bus and the left adjacent low-voltage side bus are both 1, the left incoming line backup power supply operation mode is adopted.

[0109] The charging conditions of the left incoming line backup power supply operation mode are as follows: the bus voltage logic signals of the low-voltage side bus and the left adjacent low-voltage side bus are both 0, and the duration is greater than the discharge time 15s; or the plunger of the incoming line backup power supply function is in the exit position; or the device lockout flag of the backup power supply safety interconnection device corresponding to the low-voltage side bus, the left adjacent low-voltage side bus or the right adjacent low-voltage side bus is 1; or there is a circuit breaker refusal to trip or refusal to close during the backup power supply action; or the corresponding interconnection line circuit breaker of the low-voltage side bus is in the closed position; or the low-voltage side bus and the left adjacent section circuit breaker are open; or the right interconnection priority logic signal is "1".

[0110] The action logic of the left incoming line backup power supply operation mode includes: when the left incoming line backup power supply mode charging is completed, the left incoming line backup power supply mode is started, and the main transformer secondary total circuit breaker corresponding to the low-voltage side bus of the current section and the "left incoming line backup power supply mode tripping" message are tripped after a one-time tripping delay T1. The main transformer secondary total circuit breaker command is cancelled after a 100 ms delay. If the main transformer secondary total circuit breaker is not tripped within 5s of sending the tripping command, "left incoming line backup power supply 1DL refuses to trip" is sent, and if the low-voltage side bus tie-in switch of the current section is not tripped within 5s (the bus tie-in switch is in the input position and the tie-in switch position is connected to the device), "left incoming line backup power supply tie-in switch refuses to trip" and "left incoming line backup power supply fails" alarms are sent; after confirming that the main transformer secondary total circuit breaker and the corresponding tie-in switch are tripped, a "left incoming line backup power supply tripping and tie-in switch success" signal is sent to the left adjacent backup power supply safety tie-in device (note: this device is defined as the "left tie-in switch out" signal, and the opposite device is defined as the "right tie-in switch in" signal). Then, the low-voltage side bus of the current section maintains the current state, and after a delay T2, if the three-phase bus voltage is normal, "left incoming line backup power supply success" message is sent; otherwise, "left incoming line backup power supply fails" message is sent.

[0111] Further, the backup power supply safety tie-in device determines the backup power supply operation mode under different power supply modes according to the voltage signal, protection action signal, switch signal and received logic state signal of the device itself, including:

[0112] In the non-main transformer power supply mode, the right adjacent section circuit breaker signal indicates that the right adjacent section circuit breaker is in the closed position, the main transformer secondary total circuit breaker signal corresponding to the low-voltage side bus of the current section indicates that the main transformer secondary total circuit breaker is in the tripped position, the tie-in line circuit breaker signal corresponding to the low-voltage side bus of the current section indicates that the tie-in line circuit breaker is in the split position, the position signal of the incoming line backup power supply function pressure plate indicates that the incoming line backup power supply function pressure plate is in the input position, the device lockout flags of the backup power supply safety tie-in devices corresponding to the low-voltage side bus of the current section, the left adjacent low-voltage side bus and the right adjacent low-voltage side bus are all 0, and the bus voltage logic signals of the low-voltage side bus of the current section and the right adjacent low-voltage side bus are both 1, then the main transformer backup power supply operation mode with the right adjacent section circuit breaker closed is adopted.

[0113] The incoming line backup power supply function pressure plate includes a soft pressure plate and a hard pressure plate. If the soft pressure plate is input, the main transformer secondary total circuit breaker corresponding to the low-voltage side bus of the current section meets the voltage condition; if the soft pressure plate is not input, whether the main transformer secondary total circuit breaker corresponding to the low-voltage side bus of the current section has voltage is not detected.

[0114] The above is the charging condition of the main transformer backup power supply operation mode when the right adjacent sectional circuit breaker is closed. The discharge conditions include: the bus voltage logic signals of the current section low-voltage side bus and the right adjacent low-voltage side bus are both 0, and the duration is greater than the discharge time 15S; or, the soft pressure plate is put into, the voltage of the current section low-voltage side bus corresponding to the main transformer secondary total circuit breaker is lower than the line no-voltage setting value, and the duration is greater than the discharge time 15S; or, the right adjacent sectional circuit breaker is manually tripped; or, the pressure plate of the incoming line backup power supply function is in the exit position; or, the device locking flags of the backup power supply safety interlocking devices corresponding to the current section low-voltage side bus, the left adjacent low-voltage side bus or the right adjacent low-voltage side bus are 1; during the backup power supply action, there is a circuit breaker refusal to trip or refusal to close (including adjacent device opening signals); or, the current section low-voltage side bus corresponding main transformer secondary total circuit breaker is closed; or, the current section low-voltage side bus corresponding interconnection line circuit breaker is in the closed position; or, the right adjacent sectional circuit breaker protection trips.

[0115] The action logic of the main transformer backup power supply operation mode when the right adjacent sectional circuit breaker is closed includes: when the charging condition is completed, the "left incoming line backup power supply tripping and interlocking switch success" signal of the right adjacent backup power supply safety interlocking device is received (note: the device is defined as the "right interlocking input" signal, and the opposite device is defined as the "left interlocking output" signal), a closing delay T2 is added to the command to close the current section low-voltage side bus corresponding main transformer secondary total circuit breaker and the "main transformer backup power supply mode closing when the right adjacent sectional circuit breaker is closed" message, and the closing main transformer secondary total circuit breaker command is cancelled after a 100 millisecond delay. If the main transformer secondary total circuit breaker does not close within 5S of issuing the command, "main transformer backup power supply refusal to close when the right adjacent sectional circuit breaker is closed" and "main transformer backup power supply backup power supply failure when the right adjacent sectional circuit breaker is closed" alarms are issued; if it is confirmed that the main transformer secondary total circuit breaker is closed, the "main transformer backup power supply backup power supply success when the right adjacent sectional circuit breaker is closed" message is issued.

[0116] Further, in the non-main transformer power supply mode, the left adjacent sectional circuit breaker signal shows that the left adjacent sectional circuit breaker is in the closed position, the main transformer secondary total circuit breaker signal corresponding to the current section low-voltage side bus shows that the main transformer secondary total circuit breaker is in the tripped position, the interconnection line circuit breaker signal corresponding to the current section low-voltage side bus shows that the interconnection line circuit breaker is in the split position, the pressure plate position signal of the incoming line backup power supply function shows that the pressure plate of the incoming line backup power supply function is in the put-in position, the device locking flags of the backup power supply safety interlocking devices corresponding to the current section low-voltage side bus, the left adjacent low-voltage side bus and the right adjacent low-voltage side bus are all 0, and the bus voltage logic signals of the current section low-voltage side bus and the left adjacent low-voltage side bus are both 1, then the main transformer backup power supply operation mode when the left adjacent sectional circuit breaker is closed is adopted.

[0117] The press plate of the incoming line spare power transfer function includes a soft press plate and a hard press plate. If the soft press plate is put into operation, the main transformer secondary total circuit breaker corresponding to the low-voltage side bus of the section meets the voltage condition. If the soft press plate is not put into operation, whether the main transformer secondary total circuit breaker corresponding to the low-voltage side bus of the section has voltage is not detected.

[0118] The charging condition of the main transformer spare power transfer operation mode when the left adjacent sectional circuit breaker is closed is as above. The discharging condition includes that the bus voltage logic signals of the low-voltage side bus of the section and the left adjacent low-voltage side bus are both 0, and the duration is greater than the discharging time 15S; or when the soft press plate is put into operation, the voltage of the main transformer secondary total circuit breaker corresponding to the low-voltage side bus of the section is lower than the line voltage value without voltage, and the duration is greater than the discharging time 15S; or the left adjacent sectional circuit breaker is manually tripped; or the press plate of the incoming line spare power transfer function is in the exit position; or the device locking flag of the spare power transfer safety interlocking device corresponding to the low-voltage side bus of the section, the left adjacent low-voltage side bus or the right adjacent low-voltage side bus is 1; or during the action of the spare power transfer, there is a circuit breaker refusal to trip or refusal to close (including adjacent device signals); or the main transformer secondary total circuit breaker corresponding to the low-voltage side bus of the section is closed; or the main transformer secondary total circuit breaker corresponding to the low-voltage side bus of the section is in the closed position; or the left adjacent sectional circuit breaker protection is tripped.

[0119] The action logic of the main transformer spare power transfer operation mode when the left adjacent sectional circuit breaker is closed includes that when the charging condition is completed, the "right incoming line spare power transfer tripping and interlocking switch success" signal of the left adjacent spare power transfer safety interlocking device is received (remark: the device is defined as "left interlocking in" signal, and the opposite device is defined as "right interlocking out" signal), a closing delay T2 is added to the command of closing the main transformer secondary total circuit breaker corresponding to the low-voltage side bus of the section and the "main transformer spare power transfer mode closing when the left adjacent sectional circuit breaker is closed" message, and the closing main transformer secondary total circuit breaker command is cancelled after 100 milliseconds. If the main transformer secondary total circuit breaker is not closed within 5S of issuing the closing command, the "main transformer spare power transfer refusal to close when the left adjacent sectional circuit breaker is closed" and "main transformer spare power transfer failure when the left adjacent sectional circuit breaker is closed" alarm is issued. If it is confirmed that the main transformer secondary total circuit breaker is closed, the "main transformer spare power transfer refusal to close when the left adjacent sectional circuit breaker is closed" and "main transformer spare power transfer failure when the left adjacent sectional circuit breaker is closed" alarm is issued.

[0120] Further, in the non-main transformer power supply mode, the left adjacent sectionalizer signal and the right adjacent sectionalizer signal show that the left adjacent sectionalizer and the right adjacent sectionalizer are in the split position, the main transformer sub-total circuit breaker signal corresponding to the low-voltage side bus of the section shows that the main transformer sub-total circuit breaker is in the split position, the tie-line circuit breaker signal corresponding to the low-voltage side bus of the section shows that the tie-line circuit breaker is in the post-closed position, the device locking flags of the low-voltage side bus backup automatic switching safety interlocking device corresponding to the low-voltage side bus of the section and the tie-line are both 0, the tie-line backup automatic switching function plunger position signal shows that the plunger of the tie-line backup automatic switching function is in the input position, and the bus voltage logic signals of the low-voltage side bus corresponding to the low-voltage side bus of the section and the tie-line are both 1, and then the tie-line main transformer backup automatic switching operation mode is adopted.

[0121] The charging conditions of the tie-line main transformer backup automatic switching operation mode are as above, and the discharge conditions thereof include that the bus voltage logic of the low-voltage side bus corresponding to the low-voltage side bus of the section and the tie-line are both 0 and the duration is greater than the discharge time 15S; or the left adjacent sectionalizer is in the closed position; or the right adjacent sectionalizer is in the closed position; the plunger of the tie-line backup automatic switching function is in the exit position; the device locking flag of the low-voltage side bus backup automatic switching safety interlocking device corresponding to the low-voltage side bus of the section or the tie-line is 1; or, during the backup automatic switching action, there is a circuit breaker refusal to trip or to close (excluding adjacent device signals); or the main transformer sub-total circuit breaker corresponding to the low-voltage side bus of the section is in the closed position; or the tie-line circuit breaker corresponding to the low-voltage side bus of the section is in the split position.

[0122] The action logic of the tie-line main transformer backup automatic switching operation mode includes that the tie-line circuit breaker corresponding to the low-voltage side bus of the section and the "tie-line main transformer backup automatic switching mode tripping" message are tripped by a tripping delay T1. The tie-line circuit breaker command is cancelled after a 100 ms delay. If the tie-line circuit breaker is not tripped within 5s of the command, the "tie-line main transformer backup automatic switching refusal to trip" is sent, and if the low-voltage side bus interlocking switch corresponding to the low-voltage side bus of the section is not tripped within 5s (the low-voltage side bus interlocking switch is in the input position and the interlocking switch position is connected to the device), the "tie-line main transformer backup automatic switching interlocking switch refusal to trip" and "tie-line main transformer backup automatic switching failure" alarms are sent; after confirming that the tie-line circuit breaker and the corresponding interlocking switch are tripped, a main transformer sub-total circuit breaker command and a "tie-line main transformer backup automatic switching mode closing" message are sent by a closing delay T2, and the main transformer sub-total circuit breaker command is cancelled after a 100 ms delay. If the main transformer sub-total circuit breaker is not closed within 5s of the main transformer sub-total circuit breaker command, the "main transformer sub-total circuit breaker refusal to close" and "tie-line main transformer backup automatic switching backup failure" alarms are sent; if it is confirmed that the main transformer sub-total circuit breaker is closed, the "tie-line main transformer backup automatic switching success" message is sent.

[0123] In addition, with reference to Figure 2 In some embodiments, the backup automatic switching safety interlocking device can also realize the interlocking function:

[0124] The low-voltage side bus I section three-phase voltage is normal and the bus live indicator has voltage, the bus voltage logic is "1", when it changes to the bus three-phase voltage being all zero and the bus live indicator having no voltage, the bus voltage logic is "0", and the device blocking flag of the low-voltage side bus I section backup power automatic switching safety interlocking device is 0, which is an effective condition, and the low-voltage side bus tie line A0 and active lines A1-A4 of the section are not delayed to be exported and tripped.

[0125] The low-voltage side bus II section three-phase voltage is normal and the bus live indicator has voltage, the bus voltage logic is "1", when it changes to the bus three-phase voltage being all zero and the bus live indicator having no voltage, the bus voltage logic is "0", and the device blocking flag of the low-voltage side bus II section backup power automatic switching safety interlocking device is 0, which is an effective condition, and the low-voltage side bus tie line B0 and active lines B1-B4 of the section are not delayed to be exported and tripped.

[0126] The low-voltage side bus III section three-phase voltage is normal and the bus live indicator has voltage, the bus voltage logic is "1", when it changes to the bus three-phase voltage being all zero and the bus live indicator having no voltage, the bus voltage logic is "0", and the device blocking flag of the low-voltage side bus I section backup power automatic switching safety interlocking device is 0, which is an effective condition, and the bus tie line C0 and active lines C1-C4 of the section are not delayed to be exported and tripped.

[0127] In some embodiments, a backup power automatic switching control system based on voltage double criteria is also provided, including at least two transformer substations, the transformer substations including at least two main transformers, the at least two main transformers adopting single bus section wiring, each low-voltage side bus being provided with a tie line for tie-in with a low-voltage side bus of another transformer substation, and each low-voltage side bus being provided with a backup power automatic switching safety interlocking device;

[0128] The backup power automatic switching safety interlocking device is used to collect voltage signals, protection action signals and switch signals of the corresponding low-voltage side bus, judge according to the voltage signals, protection action signals and switch signals of the low-voltage side bus, generate a logic state signal and send it to other backup power automatic switching safety interlocking devices of the transformer substation and corresponding backup power automatic switching safety interlocking devices of other transformer substations;

[0129] The backup power automatic switching safety interlocking device is also used to comprehensively judge according to the voltage signals, protection action signals, switch signals and received logic state signals of itself to determine backup power automatic switching operation modes under different power supply modes.

[0130] The backup power automatic switching control method and system based on voltage double criteria provided by the above embodiments at least have the following beneficial effects:

[0131] (1) Each low-voltage side bus is equipped with a backup automatic transfer safety interlocking device, and adjacent backup automatic transfer safety interlocking devices can communicate with each other. The voltage signal, protection action signal and switch signal are used to make comprehensive logic judgments to realize reliable, accurate and fast tripping and closing of the associated circuit breaker and quickly restore the power supply of this bus section.

[0132] (2) Abandon the existing current as the logical judgment condition. For the logical judgment of the bus voltage, the bus voltage signal and the low-voltage side bus energized indicator signal are used for joint judgment, which can effectively avoid the failure of no-current blocking.

[0133] (3) Adjacent backup automatic transfer safety interlocking devices can exchange signals and block each other to avoid competition between different devices or abnormal looping between adjacent busbars.

[0134] (4) The automatic transfer operation mode under different power supply modes is proposed, which is applicable to a variety of application scenarios and further ensures the reliability of power supply;

[0135] (5) The method proposed in the above embodiments only involves the newly built busbar during commissioning and has no impact on the previously built busbar, which facilitates the expansion of the substation;

[0136] (6) The method proposed in the above embodiments is applicable to the working condition of inter-substation with tie lines. Based on the original automatic transfer switch operation logic which only has the automatic transfer switch function of incoming line and automatic transfer switch function of bridge, the automatic transfer switch scheme of tie line is adopted to realize mutual backup between substations.

[0137] (7) The method provided in the above embodiments can prevent islanding and asynchronous closing. When any low-voltage busbar in the substation experiences temporary or permanent loss of voltage, the active line connected to that busbar can be reliably disconnected, effectively improving the reliability of the system.

[0138] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. A method for automatic switching control of backup power supply based on dual voltage criteria, characterized in that, The method is applied to a substation, which includes at least two main transformers. These at least two main transformers are connected in a single busbar segmented configuration. Each low-voltage side busbar segment is connected to the low-voltage side busbars of other substations via a tie line. Each low-voltage side busbar segment is equipped with a backup automatic transfer safety interlocking device. The method includes: The automatic transfer switch safety interlocking device collects the voltage signal, protection action signal and switch signal of the corresponding low-voltage side bus, makes judgment based on the voltage signal, protection action signal and switch signal of the low-voltage side bus, generates a logic status signal and sends it to other automatic transfer switch safety interlocking devices in the substation and other corresponding automatic transfer switch safety interlocking devices in the substation. The automatic transfer switch safety interlock device performs a comprehensive logical judgment based on its own voltage signal, protection action signal, switch signal and received logic status signal to determine the automatic transfer switch operation mode under different power supply methods. The protection action signals include the main transformer protection action signal and the tie line protection action signal; the switching signals include the main transformer secondary circuit breaker manual tripping signal, the tie line circuit breaker manual tripping signal, and the sectional circuit breaker position status; the logic status signals include the device lockout flag. The automatic transfer switch (ATS) safety interlocking device generates a logic status signal based on the protection action signal and the switch signal, including: the ATS safety interlocking device determines whether a main transformer protection action has occurred based on the main transformer protection action signal; if a main transformer protection action occurs, the ATS safety interlocking device is locked; the ATS safety interlocking device determines whether a tie-line protection action has occurred based on the tie-line protection action signal; if a tie-line protection action occurs and there is a fault on the low-voltage side busbar of this section, the ATS safety interlocking device is locked. The automatic transfer switch safety interlocking device is locked. Based on the manual tripping signals of the main transformer secondary circuit breaker and the tie line circuit breaker, the automatic transfer switch safety interlocking device determines whether a manual tripping of the main transformer secondary circuit breaker or the tie line circuit breaker has occurred. When either a manual tripping of the main transformer secondary circuit breaker or the tie line circuit breaker occurs, the automatic transfer switch safety interlocking device is locked. After the automatic transfer switch safety interlocking device is locked, the device lockout flag is set to 1. If the automatic transfer switch safety interlocking device is not locked, the device lockout flag is 0. The logic status signal also includes a bus voltage logic signal; the backup automatic transfer safety interlocking device judges based on the voltage signal of the low-voltage side bus and generates a logic status signal, including: acquiring the low-voltage side bus energized indicator signal and performing a consistency check between the low-voltage side bus energized indicator signal and the voltage signal: when both the voltage signal and the low-voltage side bus energized indicator signal are normal, a bus voltage logic signal 1 is generated; when both the voltage signal and the low-voltage side bus energized indicator signal are abnormal, a bus voltage logic signal 0 is generated. The method further includes: generating an alarm signal when the voltage signal is normal and the low-voltage side bus energizer indicator signal is abnormal, or when the voltage signal is abnormal and the low-voltage side bus energizer indicator signal is normal; With left and right as logical relative positions, each low-voltage side busbar section includes the left adjacent low-voltage side busbar and the right adjacent low-voltage side busbar, and is respectively equipped with the left adjacent section circuit breaker and the right adjacent section circuit breaker; The switching signals include the main transformer secondary circuit breaker signal, tie line circuit breaker signal, left adjacent section circuit breaker signal, right adjacent section circuit breaker signal, section automatic transfer switch position signal, tie line automatic transfer switch position signal, and incoming line automatic transfer switch position signal. The logic status signal also includes a tie-line power supply mode signal; The backup automatic transfer safety interlocking device determines the status based on the switch signal and generates a logic status signal, including: The backup automatic transfer safety interlock device determines whether the low-voltage side busbar of this section is powered by the tie line based on the tie line circuit breaker signal. If the tie line circuit breaker signal shows that the tie line circuit breaker is in the closed position, it determines that the low-voltage side busbar of this section is powered by the tie line and sets the tie line power supply mode signal to 1; otherwise, it sets the tie line power supply mode signal to 0.

2. The method according to claim 1, characterized in that, The automatic transfer switch safety interlocking device performs comprehensive logical judgment based on its own voltage signal, protection action signal, switch signal, and received logic status signal to determine the automatic transfer switch operation mode under different power supply methods, including: Under the main transformer power supply mode, if the main transformer secondary main circuit breaker signal corresponding to the low-voltage side bus of this section shows that the main transformer secondary main circuit breaker is in the closed position, the tie line circuit breaker signal shows that the tie line circuit breaker is in the open position, the left adjacent section circuit breaker signal and the right adjacent section circuit breaker signal show that the left adjacent section circuit breaker and the right adjacent section circuit breaker are both in the tripped position, the section backup automatic transfer switch position signal shows that the section backup automatic transfer switch is in the engaged position, the device interlocking flag of the backup automatic transfer safety interlocking device corresponding to the low-voltage side bus of this section, the left adjacent low-voltage side bus, and the right adjacent low-voltage side bus are all 0, the bus voltage logic signal of the low-voltage side bus of this section and the right adjacent low-voltage side bus are both 1, the tie line power supply mode signal corresponding to the right adjacent low-voltage side bus is 0, and the bus voltage logic signal of the left adjacent low-voltage side bus is 0 or the bus voltage logic signal of the left adjacent low-voltage side bus is 1 and the right tie priority logic signal is 1, then the right tie section backup automatic transfer operation mode is determined to be adopted. Under the main transformer power supply mode, if the main transformer secondary main circuit breaker signal corresponding to the low-voltage side bus of this section shows that the main transformer secondary main circuit breaker is in the closed position, the tie line circuit breaker signal shows that the tie line circuit breaker is in the open position, the left adjacent section circuit breaker signal and the right adjacent section circuit breaker signal show that the left adjacent section circuit breaker and the right adjacent section circuit breaker are both in the tripped position, the section backup automatic transfer switch position signal shows that the section backup automatic transfer switch is in the engaged position, the device interlocking flag of the backup automatic transfer safety interlocking device corresponding to the low-voltage side bus of this section, the left adjacent low-voltage side bus, and the right adjacent low-voltage side bus are all 0, the bus voltage logic signal of the low-voltage side bus of this section and the left adjacent low-voltage side bus are both 1, the tie line power supply mode signal corresponding to the left adjacent low-voltage side bus is 0, and the bus voltage logic signal of the right adjacent low-voltage side bus is 0 or the bus voltage logic signal of the right adjacent low-voltage side bus is 1 and the left tie priority logic signal is 1, then the left tie section backup automatic transfer operation mode is determined to be adopted.

3. The method according to claim 2, characterized in that, The left connection priority logic signal and the right connection priority logic signal are external inputs; Under the right-side segmented automatic transfer operation mode, the right adjacent segment circuit breaker is controlled to close. In the left-side segmented automatic transfer operation mode, the left adjacent segment circuit breaker is controlled to close.

4. The method according to claim 1, characterized in that, The automatic transfer switch safety interlocking device performs comprehensive logical judgment based on its own voltage signal, protection action signal, switch signal, and received logic status signal to determine the automatic transfer switch operation mode under different power supply methods, including: Under the main transformer power supply mode, if the left adjacent section circuit breaker signal and the right adjacent section circuit breaker signal show that the left adjacent section circuit breaker and the right phase section circuit breaker are both in the open position, the main transformer secondary main circuit breaker signal corresponding to the low voltage side bus of this section shows that the main transformer secondary main circuit breaker is in the closed position, the tie line circuit breaker signal corresponding to the low voltage side bus of this section shows that the tie line circuit breaker of the low voltage side bus of this section is in the open position, the tie line backup automatic transfer switch position signal shows that the tie line backup automatic transfer switch is in the engaged position, the device interlocking flag of the backup automatic transfer safety interlocking device corresponding to the low voltage side bus of this section and the tie line is 0, and the bus voltage logic signal of the low voltage side bus of this section and the tie line is 1, then it is determined that the tie line backup automatic transfer operation mode is adopted. In the automatic transfer switch operation mode of the tie line, the low-voltage side busbar and the corresponding tie line circuit breaker of this section are controlled to close.

5. The method according to claim 2, characterized in that, The automatic transfer switch safety interlocking device performs comprehensive logical judgment based on its own voltage signal, protection action signal, switch signal, and received logic status signal to determine the automatic transfer switch operation mode under different power supply methods, including: Under the main transformer power supply mode, if the main transformer secondary main circuit breaker signal corresponding to the low-voltage side busbar of this section shows that the main transformer secondary main circuit breaker is in the closed position, the tie line circuit breaker signal shows that the tie line circuit breaker is in the open position, the right adjacent section circuit breaker signal shows that the right adjacent section circuit breaker is in the closed position, the incoming line standby automatic transfer switch position signal shows that the incoming line standby automatic transfer switch position is in the engaged position, the left adjacent section circuit breaker signal shows that the left adjacent section circuit breaker is in the open position or the left adjacent section circuit breaker is in the closed position and the right tie priority logic signal is 1, the device interlocking flag of the standby automatic transfer safety interlocking device corresponding to the low-voltage side busbar of this section, the left adjacent low-voltage side busbar and the right adjacent low-voltage side busbar are all 0, and the bus voltage logic signal of the low-voltage side busbar of this section and the right adjacent low-voltage side busbar are all 1, then the right incoming line standby automatic transfer operation mode is adopted; Under the main transformer power supply mode, if the main transformer secondary main circuit breaker signal corresponding to the low-voltage side bus of this section shows that the main transformer secondary main circuit breaker is in the closed position, the tie line circuit breaker signal shows that the tie line circuit breaker is in the open position, the left adjacent section circuit breaker signal shows that the left adjacent section circuit breaker is in the closed position, the incoming line standby automatic transfer switch position signal shows that the incoming line standby automatic transfer switch position is in the engaged position, the right adjacent section circuit breaker signal shows that the right adjacent section circuit breaker is in the open position or the right section circuit breaker is in the closed position and the left tie priority logic signal is 1, the device interlocking flag of the standby automatic transfer safety interlocking device corresponding to the low-voltage side bus of this section, the left adjacent low-voltage side bus, and the right adjacent low-voltage side bus are all 0, and the bus voltage logic signal of the low-voltage side bus of this section and the left adjacent low-voltage side bus are all 1, then the left incoming line standby automatic transfer operation mode is adopted.

6. The method according to claim 1, characterized in that, The automatic transfer switch safety interlocking device performs comprehensive logical judgment based on its own voltage signal, protection action signal, switch signal, and received logic status signal to determine the automatic transfer switch operation mode under different power supply methods, including: In non-main transformer power supply mode, the right adjacent section circuit breaker signal indicates that the right adjacent section circuit breaker is in the closed position; the main transformer secondary main circuit breaker signal corresponding to the low-voltage side bus of this section indicates that the main transformer secondary main circuit breaker is in the tripped position; the tie line circuit breaker signal corresponding to the low-voltage side bus of this section indicates that the tie line circuit breaker is in the open position; the incoming line standby automatic transfer switch position signal indicates that the incoming line standby automatic transfer switch position is in the engaged position; the device interlocking flag of the standby automatic transfer safety interlocking device corresponding to the low-voltage side bus of this section, the left adjacent low-voltage side bus, and the right adjacent low-voltage side bus are all 0; the bus voltage logic signal of the low-voltage side bus of this section and the right adjacent low-voltage side bus are all 1; then the main transformer standby automatic transfer operation mode with the right adjacent section circuit breaker closed is adopted. In non-main transformer power supply mode, the left adjacent section circuit breaker signal indicates that the left adjacent section circuit breaker is in the closed position, the main transformer secondary main circuit breaker signal corresponding to the low voltage side bus of this section indicates that the main transformer secondary main circuit breaker is in the tripped position, the tie line circuit breaker signal corresponding to the low voltage side bus of this section indicates that the tie line circuit breaker is in the open position, the incoming line standby automatic transfer switch position signal indicates that the incoming line standby automatic transfer switch position is in the engaged position, the device interlocking flag of the standby automatic transfer safety interlocking device corresponding to the low voltage side bus of this section, the left adjacent low voltage side bus, and the right adjacent low voltage side bus are all 0, and the bus voltage logic signal of the low voltage side bus of this section and the left adjacent low voltage side bus are all 1. Then the main transformer standby automatic transfer operation mode with the left adjacent section circuit breaker in the closed position is adopted. In non-main transformer power supply mode, the left adjacent section circuit breaker signal and the right adjacent section circuit breaker signal indicate that the left adjacent section circuit breaker and the right adjacent section circuit breaker are in the open position. The main transformer secondary main circuit breaker signal corresponding to the low-voltage side bus of this section indicates that the main transformer secondary main circuit breaker is in the open position. The tie line circuit breaker signal corresponding to the low-voltage side bus of this section indicates that the tie line circuit breaker is in the closed position. The device interlocking flag of the backup automatic transfer safety interlocking device of the low-voltage side bus of this section and the tie line is 0. The tie line backup automatic transfer pressure plate position signal indicates that the tie line backup automatic transfer pressure plate is in the engaged position. The bus voltage logic signal of the low-voltage side bus of this section and the tie line is 1. Then the tie line main transformer backup automatic transfer operation mode is adopted.

7. A backup power supply automatic switching control system based on dual voltage criteria, characterized in that, It includes at least two substations, each substation including at least two main transformers. The at least two main transformers adopt a single busbar segmented connection. Each low-voltage side busbar segment is equipped with a tie line to connect with the low-voltage side busbars of other substations. Each low-voltage side busbar segment is equipped with a backup automatic transfer safety interlocking device. The automatic transfer switch safety interlocking device is used to collect the voltage signal, protection action signal and switch signal of the corresponding low-voltage side bus, make judgments based on the voltage signal, protection action signal and switch signal of the low-voltage side bus, generate a logic status signal and send it to other automatic transfer switch safety interlocking devices in the substation and other corresponding automatic transfer switch safety interlocking devices in the substation. The automatic transfer switch safety interlocking device is also used to perform comprehensive logical judgment based on its own voltage signal, protection action signal, switch signal and received logic status signal to determine the automatic transfer operation mode under different power supply methods; The protection action signals include the main transformer protection action signal and the tie line protection action signal; the switching signals include the main transformer secondary circuit breaker manual tripping signal, the tie line circuit breaker manual tripping signal, and the sectional circuit breaker position status; the logic status signals include the device lockout flag. The automatic transfer switch (ATS) safety interlocking device generates a logic status signal based on the protection action signal and the switch signal, including: the ATS safety interlocking device determines whether a main transformer protection action has occurred based on the main transformer protection action signal; if a main transformer protection action occurs, the ATS safety interlocking device is locked; the ATS safety interlocking device determines whether a tie-line protection action has occurred based on the tie-line protection action signal; if a tie-line protection action occurs and there is a fault on the low-voltage side busbar of this section, the ATS safety interlocking device is locked. The automatic transfer switch safety interlocking device is locked. Based on the manual tripping signals of the main transformer secondary circuit breaker and the tie line circuit breaker, the automatic transfer switch safety interlocking device determines whether a manual tripping of the main transformer secondary circuit breaker or the tie line circuit breaker has occurred. When either a manual tripping of the main transformer secondary circuit breaker or the tie line circuit breaker occurs, the automatic transfer switch safety interlocking device is locked. After the automatic transfer switch safety interlocking device is locked, the device lockout flag is set to 1. If the automatic transfer switch safety interlocking device is not locked, the device lockout flag is 0. The logic status signal also includes a bus voltage logic signal; the backup automatic transfer safety interlocking device judges based on the voltage signal of the low-voltage side bus and generates a logic status signal, including: acquiring the low-voltage side bus energized indicator signal and performing a consistency check between the low-voltage side bus energized indicator signal and the voltage signal: when both the voltage signal and the low-voltage side bus energized indicator signal are normal, a bus voltage logic signal 1 is generated; when both the voltage signal and the low-voltage side bus energized indicator signal are abnormal, a bus voltage logic signal 0 is generated. An alarm signal is generated when the voltage signal is normal and the low-voltage side bus energizer indicator signal is abnormal, or when the voltage signal is abnormal and the low-voltage side bus energizer indicator signal is normal. With left and right as logical relative positions, each low-voltage side busbar section includes the left adjacent low-voltage side busbar and the right adjacent low-voltage side busbar, and is respectively equipped with the left adjacent section circuit breaker and the right adjacent section circuit breaker; The switching signals include the main transformer secondary circuit breaker signal, tie line circuit breaker signal, left adjacent section circuit breaker signal, right adjacent section circuit breaker signal, section automatic transfer switch position signal, tie line automatic transfer switch position signal, and incoming line automatic transfer switch position signal. The logic status signal also includes a tie-line power supply mode signal; The backup automatic transfer safety interlocking device determines the status based on the switch signal and generates a logic status signal, including: The backup automatic transfer safety interlock device determines whether the low-voltage side busbar of this section is powered by the tie line based on the tie line circuit breaker signal. If the tie line circuit breaker signal shows that the tie line circuit breaker is in the closed position, it determines that the low-voltage side busbar of this section is powered by the tie line and sets the tie line power supply mode signal to 1; otherwise, it sets the tie line power supply mode signal to 0.

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