Standby power supply automatic switching control method and system based on voltage double criteria

Abstract

The invention discloses a backup power supply automatic switching control method and system based on voltage double criteria, and the method is applied to a transformer substation, and comprises the steps: enabling a backup power supply automatic switching safety intertripping device to collect a voltage signal, a protection action signal and a switching signal of a corresponding low-voltage side bus; judging according to the voltage signal of the low-voltage side bus, the protection action signal and the switching signal, generating a logic state signal, and sending the logic state signal to other spare power automatic switching safety intertripping devices of the transformer substation and corresponding spare power automatic switching safety intertripping devices of other transformer substations; the backup power automatic switching safety intertripping device performs comprehensive logic judgment according to the voltage signal, the protection action signal and the switching signal of the backup power automatic switching safety intertripping device and the received logic state signal, and determines backup power automatic switching operation modes under different power supply modes; the method can ensure the reliability of power supply.

Description

Technical Field

[0001] The present invention relates to the field of electrical technology, and in particular to a method and system for automatically switching a backup power supply based on voltage dual criteria. Background Art

[0002] The automatic switching device of the backup power supply is an automatic device installed in the power system to improve the reliability of power supply. It plays an important role in improving the reliability of load power supply and ensuring continuous power supply. When one working voltage fails and loses voltage, the device quickly cuts off the faulty voltage line and puts another normal working power supply into operation. At present, the automatic switching device of the backup power supply (hereinafter referred to as the "automatic switching device") is configured separately from the safe and stable joint switching device. The safe and stable joint switching performs action logic judgment based on the external input signals of the automatic switching device. Due to the current access of a large number of distributed power sources, the actual working current of the main transformer sub-main switch cabinet is often less than 5% of the rated working current (there is randomness), resulting in the phenomenon of no-current lock failure.

[0003] At present, when the automatic switching device of the backup power supply is applied to the 35(10) kV busbar on the low-voltage side of the substation, generally, one set of automatic switching device (including the incoming line automatic switching function and the bridge automatic switching function) is configured for the two sections of the low-voltage side busbar, and three main transformers need to be configured with more than two sets of automatic switching devices, and some functions are locked. For example, a substation has three main transformers, 220 / 110 / 35 kV, and three sections of single busbar on the low-voltage side are connected in three sections. The No. 1 and No. 2 main transformers and the No. 2 and No. 3 low-voltage sides are each equipped with one set of automatic switching device. In normal operation, the No. 1, No. 2, and No. 3 main transformers carry 35 kV I, II, and III sections of busbars respectively. When the upper power supply of the No. 2 main transformer loses voltage, the two sets of automatic switching devices both start the bridge automatic switching function, resulting in competition or abnormal closing of the 35 kV I and III sections of busbars. Patent document CN110323821A discloses a control method for automatic switching of a multi-segment ring network switch cabinet, including multiple busbars arranged in sequence, each of which is connected to a circuit breaker at both ends on one side, and the other side is connected to the main transformer through an incoming circuit breaker, the two circuit breakers close to the two adjacent busbars are short-circuited, and the remaining two circuit breakers of the front and the last two busbars are short-circuited, so that multiple circuit breakers on the multi-segment busbars form a ring connection together, and the series connection between the undervoltage section busbar and the left section busbar or the right section busbar is realized by closing the two short-circuited circuit breakers on the left side of the undervoltage section busbar, or closing the two short-circuited circuit breakers on the right side, thereby realizing the automatic switching operation between the multi-segment busbars. However, during the operation of this method, it is necessary to determine the operation mode of the automatic switching by opening and closing the switch and detecting the voltage, and the degree of automation is low.

[0004] In addition, the original standby automatic switching action logic only includes the incoming line standby automatic switching function and the bridge standby automatic switching function. Moreover, when the new busbar of the substation is expanded, the on-site debugging of the original standby power automatic switching device requires the simultaneous shutdown of the previously built busbar for debugging (because the two busbars are equipped with one set of standby power automatic switching device, the two busbars related to the debugging of the device are shut down at the same time), which leads to external power outages and reduced power supply reliability, with a greater impact. Summary of the invention

[0005] The present invention provides a backup power supply automatic switching control method and system based on voltage dual criteria, which can improve the reliability of power supply.

[0006] A method for automatically switching a backup power supply based on voltage dual criteria is applied to a substation, wherein the substation includes at least two main transformers, the at least two main transformers are connected in sections using a single busbar, each section of the low-voltage side busbar is provided with a connecting line to connect with the low-voltage side busbars of other substations, and each section of the low-voltage side busbar is provided with a backup automatic switching safety interlocking device; the method includes:

[0007] The standby automatic switching safety interlocking device collects the voltage signal, protection action signal and switch signal of the corresponding low-voltage side bus, makes judgments based on the voltage signal, protection action signal and switch signal of the low-voltage side bus, generates a logic state signal and sends it to other standby automatic switching safety interlocking devices of the substation where it is located and the standby automatic switching safety interlocking devices corresponding to other substations;

[0008] The standby automatic switching safety interlocking device performs comprehensive logic judgment based on its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes.

[0009] Furthermore, the protection action signal includes a main transformer protection action signal and a tie line protection action signal, the switch signal includes a main transformer secondary main circuit breaker manual opening signal, a tie line circuit breaker manual opening signal and a section circuit breaker position state; the logic state signal includes a device locking flag;

[0010] The standby automatic safety interlocking device makes a judgment based on the protection action signal and the switch signal to generate a logic state signal, including:

[0011] The standby automatic switching safety interlocking device determines whether the main transformer protection action occurs according to the main transformer protection action signal, and when the main transformer protection action occurs, the standby automatic switching safety interlocking device is locked;

[0012] The standby automatic switching safety interlocking device determines whether the tie line protection action occurs according to the tie line protection action signal. When the tie line protection action occurs and the low-voltage side busbar of this section fails, the standby automatic switching safety interlocking device is locked;

[0013] The standby automatic switching safety interlocking device determines whether the main transformer secondary circuit breaker is manually opened and the tie line circuit breaker is manually opened according to the manual opening signal of the main transformer secondary circuit breaker and the manual opening signal of the tie line circuit breaker. When the main transformer secondary circuit breaker is manually opened or the tie line circuit breaker is manually opened, the standby automatic switching safety interlocking device is locked;

[0014] After the standby automatic safety interlocking device is locked, the device locking flag is set to 1. If the standby automatic safety interlocking device is not locked, the device locking flag is 0.

[0015] Furthermore, the logic state signal also includes a bus voltage logic signal;

[0016] The standby automatic safety interlocking device makes a judgment based on the voltage signal of the low-voltage side busbar to generate a logic state signal, including:

[0017] Collect the low-voltage side bus live indicator signal, and perform consistency check 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, generate a bus voltage logic signal 1; when the voltage signal and the low-voltage side bus live indicator signal are both abnormal, generate a bus voltage logic signal 0;

[0018] The method further comprises:

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

[0020] Further, with left and right as logical relative positions, each section of the low-voltage side busbar includes a left adjacent low-voltage side busbar and a right adjacent low-voltage side busbar, and is respectively provided with a left adjacent section circuit breaker and a right adjacent section circuit breaker;

[0021] The switch signal includes the main transformer sub-circuit breaker signal, the tie line circuit breaker signal, the left adjacent section circuit breaker signal, the right adjacent section circuit breaker signal, the pressure plate position signal of the section standby automatic switching function, the pressure plate position signal of the tie line standby automatic switching function, and the pressure plate position signal of the incoming line standby automatic switching function;

[0022] The logic state signal also includes a tie line power supply mode signal;

[0023] The standby automatic safety interlocking device makes a judgment based on the switch signal and generates a logic state signal, including:

[0024] The standby automatic safety interlocking device determines whether the low-voltage side busbar of this 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 busbar of this section is powered by the tie line, and the tie line power supply mode signal is set to 1; otherwise, the tie line power supply mode signal is set to 0.

[0025] Furthermore, the standby automatic switching safety interlocking device performs comprehensive logic judgment according to its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes, including:

[0026] Under the main transformer power supply mode, if the main transformer sub-main circuit breaker signal corresponding to the low-voltage side bus of this section shows that the main transformer sub-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 pressure plate position signal of the section standby automatic transfer function shows that the pressure plate of the section standby automatic transfer function is in the put-in position, the device locking flags of the standby automatic transfer safety interlocking devices 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 signals of the low-voltage side bus of this section and the right adjacent low-voltage side bus are all 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, then it is determined to adopt the right-linked section standby automatic transfer operation mode;

[0027] 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 interconnecting line circuit breaker signal shows that the interconnecting 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 pressure plate position signal of the section standby automatic transfer function shows that the pressure plate of the section standby automatic transfer function is in the put-in position, the device locking flags of the standby automatic transfer safety interlocking devices 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 signals of the low-voltage side bus of this section and the left adjacent low-voltage side bus are both 1, the interconnecting line power supply mode signal corresponding to the left adjacent low-voltage side bus is 0, 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 interconnecting priority logic signal is 1, then it is determined that the left interconnecting section standby automatic transfer operation mode is adopted.

[0028] Further, the left contact priority logic signal and the right contact priority logic signal are external inputs;

[0029] In the right-connected sectional standby automatic switching operation mode, control the closing of the right adjacent sectional circuit breaker;

[0030] In the left-linked section standby automatic switching operation mode, the left adjacent section circuit breaker is controlled to close.

[0031] Furthermore, the standby automatic switching safety interlocking device performs comprehensive logic judgment according to its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes, including:

[0032] 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 adjacent section circuit breaker are both in the open position, the main transformer sub-main circuit breaker signal corresponding to the low-voltage side bus of this section shows that the main transformer sub-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 pressure plate position signal of the tie line standby automatic function shows that the pressure plate of the tie line standby automatic function is in the switched position, the device locking flags of the standby automatic safety interlocking device corresponding to the low-voltage side bus of this 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 this section and the low-voltage side bus corresponding to the tie line are both 1, then it is determined that the tie line standby automatic operation mode is adopted;

[0033] In the automatic standby operation mode of the interconnection line, the low-voltage busbar of this section and the corresponding interconnection line circuit breaker are controlled to close.

[0034] Furthermore, the standby automatic switching safety interlocking device performs comprehensive logic judgment according to its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes, including:

[0035] In the main transformer power supply mode, if the main transformer sub-main circuit breaker signal corresponding to the low-voltage side busbar of this section shows that the main transformer sub-main circuit breaker is in the closed position, the interconnecting line circuit breaker signal shows that the interconnecting 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 pressure plate position signal of the incoming line standby automatic function shows that the pressure plate of the incoming line standby automatic function 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 interconnection priority logic signal is 1, the device locking flags of the standby automatic safety interlocking devices 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 signals 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 operation mode is adopted;

[0036] 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 interconnecting line circuit breaker signal shows that the interconnecting 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 pressure plate position signal of the incoming line standby automatic transfer function shows that the pressure plate of the incoming line standby automatic transfer function 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 adjacent section circuit breaker is in the closed position and the left interconnection priority logic signal is 1, the device locking flags of the standby automatic transfer safety interlocking devices 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 signals of the low-voltage side bus of this section and the left adjacent low-voltage side bus are both 1, then the left incoming line standby automatic transfer operation mode is adopted.

[0037] Furthermore, the standby automatic switching safety interlocking device performs comprehensive logic judgment according to its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under 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 sub-main circuit breaker signal corresponding to the low-voltage side bus of this section shows that the main transformer sub-main circuit breaker is in the tripped position, the tie line circuit breaker signal corresponding to the low-voltage side bus of this section shows that the tie line circuit breaker is in the open position, the pressure plate position signal of the incoming line standby automatic function shows that the pressure plate of the incoming line standby automatic function is in the put-in position, the device locking flag of the standby automatic 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 signals 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 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 sub-main circuit breaker signal corresponding to the low-voltage side bus of this section shows that the main transformer sub-main circuit breaker is in the tripped position, the tie line circuit breaker signal corresponding to the low-voltage side bus of this section shows that the tie line circuit breaker is in the open position, the pressure plate position signal of the incoming line standby automatic function shows that the pressure plate of the incoming line standby automatic function is in the put-in position, the device locking flags of the standby automatic safety interlocking devices 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 signals 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 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 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 in the open position, the main transformer sub-main circuit breaker signal corresponding to the low-voltage side bus of this section shows that the main transformer sub-main circuit breaker is in the open position, the connecting line circuit breaker signal corresponding to the low-voltage side bus of this section shows that the connecting line circuit breaker is in the closed position, the device locking marks of the standby automatic safety interlocking devices of the low-voltage side bus of this section and the low-voltage side bus corresponding to the connecting line are both 0, the pressure plate position signal of the connecting line standby automatic function shows that the pressure plate of the connecting line standby automatic function is in the engaged position, the bus voltage logic signals of the low-voltage side bus of this section and the low-voltage side bus corresponding to the connecting line are both 1, then the connecting line main transformer standby automatic operation mode is adopted.

[0041] A backup power automatic switching control system based on voltage dual criteria, comprising at least two substations, the substations comprising at least two main transformers, at least two main transformers adopting single busbar segmented wiring, each section of low-voltage side busbar is provided with a connecting line to communicate with the low-voltage side busbars of other substations, and each section of low-voltage side busbar is equipped with a backup automatic switching safety interlocking device;

[0042] The standby automatic switching 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 state signal and send it to other standby automatic switching safety interlocking devices in the substation where it is located and the standby automatic switching safety interlocking devices corresponding to other substations;

[0043] The standby automatic switching safety interlocking device is also used to perform comprehensive logic judgment based on its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes.

[0044] The automatic switching control method and system of the backup power supply based on voltage dual criteria provided by the present invention have at least the following beneficial effects:

[0045] (1) Each section of the low-voltage side busbar is equipped with a backup automatic safety interlocking device, and the adjacent backup automatic safety interlocking devices can exchange signals with each other. The voltage signal, protection action signal and switch signal are used to perform comprehensive logical judgment to achieve reliable, accurate and rapid exit tripping and closing of the associated circuit breakers, and quickly restore the power supply of this section of the busbar.

[0046] (2) Abandoning the existing current as a logical judgment condition, for the logical judgment of the bus voltage, a dual judgment criterion of the bus voltage signal and the low-voltage side bus energized indicator signal is used for joint judgment, which can effectively avoid the failure of the no-current lockout;

[0047] (3) Adjacent backup automatic safety interlocking devices can exchange signals and interlock signals to avoid competition between different devices or abnormal closing of adjacent busbars;

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

[0049] (5) The method proposed in the present invention only involves the newly built busbar during debugging, and has no impact on the previously built busbar, which is convenient for the expansion of the substation;

[0050] (6) The method proposed in the present invention is applicable to the working condition of the substation with tie line. On the basis of the original standby automatic switching action logic which only has the function of incoming line standby automatic switching and bridge standby automatic switching, the tie line standby automatic switching scheme is adopted to realize the mutual standby between substations;

[0051] (7) The method provided by the present invention can prevent the occurrence of islanding and asynchronous closing phenomena. When any low-voltage side bus of the substation loses pressure temporarily or permanently, the active line connected to the bus can be reliably disconnected, effectively improving the reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 The present invention provides a flowchart of an embodiment of a method for automatically switching a backup power supply based on voltage dual criteria.

[0053] Figure 2 The present invention provides a schematic structural diagram of a transformer substation in a method for automatically switching a backup power supply based on voltage dual criteria according to an embodiment of the present invention.

[0054] Figure 3 The present invention provides a schematic structural diagram of an embodiment of a transformer substation tie line in the automatic switching control method of a backup power supply based on voltage dual criteria provided by the present invention. DETAILED DESCRIPTION

[0055] In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0056] refer to Figure 1 In some embodiments, a backup power supply automatic switching control method based on voltage dual criteria is provided, which is applied to a substation, wherein the substation includes at least two main transformers, and the at least two main transformers are connected in sections using a single busbar, and each section of the low-voltage side busbar is provided with a connecting line to connect with the low-voltage side busbars of other substations, and each section of the low-voltage side busbar is provided with a backup power supply automatic switching safety interlocking device; the method includes:

[0057] S1, the standby automatic switching safety interlocking device collects the voltage signal, protection action signal and switch signal of the corresponding low-voltage side bus, makes judgments based on the voltage signal, protection action signal and switch signal of the low-voltage side bus, generates a logic state signal and sends it to other standby automatic switching safety interlocking devices in the substation where it is located and the standby automatic switching safety interlocking devices corresponding to other substations;

[0058] S2. The standby automatic switching safety interlocking device performs comprehensive logic judgment based on its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes.

[0059] refer to Figure 2 In this embodiment, three main transformers of a 220KV substation are used for illustration. The three main transformers are main transformer No. 1, main transformer No. 2 and main transformer No. 3. The three main transformers adopt single busbar segmented wiring. Each main transformer is connected to a section of low-voltage side busbar. Each section of low-voltage side busbar is only equipped with one tie line to communicate with the opposite end substation. In principle, the tie line circuit breakers of the substations on both sides of the tie line are one closing and one opening. The normally closed circuit breaker side is considered as a feeder (no power supply), and the normally opened circuit breaker (closing and unclosing point) side is considered as an active line. Each section of the low-voltage side busbar is equipped with a standby automatic safety interlocking device and can exchange signals. Each main transformer is equipped with a main transformer sub-main circuit breaker 1DL, and segmented circuit breakers 3DL and 4DL are set between adjacent low-voltage side busbars. The tie line circuit breaker is 2DL, and A1-A4, B1-B4, and C1-C4 are active lines.

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

[0061] In addition, the main transformer protection device of each main transformer adopts a dual configuration, that is, it contains two independent main transformer protection devices, and the main transformer protection action signal is the protection action signal (passive hard contact) issued by the two main transformer protection devices respectively and combined into a signal. Main transformer protection action restriction conditions: The backup protection on the low-voltage side of the main transformer does not trip the low-voltage side section circuit breaker, and only the first time limit trips the low-voltage side of the main transformer, and the second time limit trips both sides of the main transformer.

[0062] Furthermore, the protection action signal includes a main transformer protection action signal and a tie line protection action signal, the switch signal includes a main transformer secondary main circuit breaker manual opening signal, a tie line circuit breaker manual opening signal and a section circuit breaker position state; the logic state signal includes a device locking flag;

[0063] In step S1, the standby automatic safety interlocking device makes a judgment based on the protection action signal and the switch signal to generate a logic state signal, including:

[0064] S11, the standby automatic switching safety interlocking device determines whether the main transformer protection action occurs according to the main transformer protection action signal, and when the main transformer protection action occurs, the standby automatic switching safety interlocking device is locked;

[0065] S12, the standby automatic switching safety interlocking device determines whether the tie line protection action occurs according to the tie line protection action signal, and when the tie line protection action occurs and the low-voltage side busbar of this section fails, the standby automatic switching safety interlocking device is locked;

[0066] S13, the standby automatic switching safety interlocking device determines whether the main transformer secondary main circuit breaker and the tie line circuit breaker are manually opened according to the manual opening signal of the main transformer secondary main circuit breaker and the manual opening signal of the tie line circuit breaker, and when the main transformer secondary main circuit breaker or the tie line circuit breaker is manually opened, the standby automatic switching safety interlocking device is locked;

[0067] After the standby automatic safety interlocking device is locked in S14, the device locking flag is set to 1. If the standby automatic safety interlocking device is not locked, the device locking flag is 0.

[0068] Furthermore, the logic state signal also includes a bus voltage logic signal;

[0069] In step S1, the standby automatic switching safety interlocking device makes a judgment based on the voltage signal of the low-voltage side bus and generates a logic state signal, including:

[0070] S15. Collect the low-voltage side bus power indicator signal, and perform consistency check on the low-voltage side bus power indicator signal and the voltage signal: when the voltage signal and the low-voltage side bus power indicator signal are both normal, generate a bus voltage logic signal 1; when the voltage signal and the low-voltage side bus power indicator signal are both abnormal, generate a bus voltage logic signal 0.

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

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

[0073] In new power systems, since the current locking conditions often fail (are unreliable), in order to ensure that the voltage logic signal is accurate and reliable, a logic condition for non-analog quantity sampling is added. In this embodiment, a voltage dual-criteria method is adopted: direct sampling and judgment of the bus voltage analog quantity and judgment of the bus energized indicator logic contact signal, and the logic consistency check is met. That is, when the three-phase voltages of the low-voltage side bus are normal and the bus energized indicator has pressure: the bus voltage logic is "1"; when the three-phase voltages of the bus are zero and the bus energized indicator has no pressure: the bus voltage logic is "0"; in other states, it is judged as abnormal voltage and an alarm is given.

[0074] The following are detailed descriptions of the different operating modes:

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

[0076] The working closing position of the main transformer sub-main switch corresponding to the low-voltage side busbar of this section, the main transformer sub-main switch of the adjacent low-voltage side busbar and the section circuit breakers of the two sections of low-voltage side busbars are all logical "1", that is, the main transformer corresponding to the low-voltage side busbar of this section and the adjacent main transformer are in closed loop operation, and the low-voltage side busbar of this section and the adjacent low-voltage side busbar of the corresponding low-voltage side are in parallel operation;

[0077] The sub-main switch corresponding to the low-voltage busbar of this section and the tie-line circuit breaker corresponding to the low-voltage busbar of this section are in the closed position, and the sectional circuit breakers corresponding to the low-voltage busbar of this section are in the divided position, all of which are logical "1", that is, the main transformer on this side and the main transformer on the opposite end are in closed loop operation, and the corresponding low-voltage side is in parallel operation. In principle, when the tie-line is put into operation, the low-voltage busbar of this section does not consider the parallel operation mode, that is, the tie-line only supplies the load of the low-voltage busbar of this section.

[0078] 2) Normal operation mode:

[0079] Power supply from main transformer: The busbar on the low voltage side of this section corresponds to the main transformer secondary main circuit breaker in the closed position, and the position logic is "1"; and the three-phase voltage of the busbar on this section is normal and the busbar power indicator has pressure, that is, the busbar voltage logic is "1". That is, the busbar on the low voltage side of this section 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 busbar on the low-voltage side of this section corresponds to the main transformer secondary main circuit breaker working position, the position logic is "0"; and the three-phase voltage of the busbar on the low-voltage side of this section is normal and the busbar energized indicator has pressure, the busbar voltage logic is "1". That is, the busbar on the low-voltage side of this section is not powered by the main transformer, then the main transformer operation logic flag is discharged and set to "0".

[0081] Furthermore, with left and right as logical relative positions, each section of the 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 section circuit breaker and a right adjacent section circuit breaker.

[0082] refer to Figure 2, the above left and right are used as logical relative positions. The low-voltage side busbar corresponding to No. 2 main transformer is on the left side relative to the low-voltage side busbar corresponding to No. 1 main transformer; the low-voltage side busbar corresponding to No. 1 main transformer is on the right side relative to the low-voltage side busbar corresponding to No. 2 main transformer, and the low-voltage side busbar corresponding to No. 3 main transformer is on the left side relative to the low-voltage side busbar corresponding to No. 2 main transformer; the low-voltage side busbar corresponding to No. 2 main transformer is on the right side relative to the low-voltage side busbar corresponding to No. 3 main transformer; the low-voltage side busbar corresponding to No. 3 main transformer is on the right side relative to the low-voltage side busbar corresponding to No. 1 main transformer; the low-voltage side busbar corresponding to No. 1 main transformer is on the left side relative to the low-voltage side busbar corresponding to No. 3 main transformer.

[0083] Furthermore, the switch signal includes a main transformer secondary circuit breaker signal, a tie line circuit breaker signal, a left adjacent section circuit breaker signal, a right adjacent section circuit breaker signal, a pressure plate position signal of a section standby automatic switching function, a pressure plate position signal of a tie line standby automatic switching function, and a pressure plate position signal of an incoming line standby automatic switching function;

[0084] The logic state signal also includes a tie line power supply mode signal;

[0085] In step S1, the standby automatic switching safety interlocking device makes a judgment based on the switch signal and generates a logic state signal, including:

[0086] S16. The standby automatic safety interlocking device determines whether the low-voltage busbar of this 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 busbar of this section is powered by the tie line, and the tie line power supply mode signal is set to 1; otherwise, the tie line power supply mode signal is set to 0.

[0087] Furthermore, in step S2, the standby automatic switching safety interlocking device performs a comprehensive logic judgment based on its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes, including:

[0088] 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 interconnecting line circuit breaker signal shows that the interconnecting 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 phase section circuit breaker are both in the tripped position, the pressure plate position signal of the section standby automatic transfer function shows that the pressure plate of the section standby automatic transfer function is in the put-in position, the device locking flags of the standby automatic transfer safety interlocking devices 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 signals of the low-voltage side bus of this section and the right adjacent low-voltage side bus are both 1, the interconnecting 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 interconnecting priority logic signal is 1, then it is determined to adopt the right-connected section standby automatic transfer operation mode.

[0089] Among them, the right connection 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 meets the conditions for being put into use. At this time, in order to prevent competition between the two sides, the right connection priority logic signal 1 is input externally.

[0090] The above are the charging conditions for the right-connected sectional standby automatic transfer operation mode. The discharging conditions for the right-connected sectional standby automatic transfer operation mode include:

[0091] The low-voltage busbar on this section or the right adjacent low-voltage busbar on this section meets the no-voltage condition, that is, the busbar voltage logic signal of the low-voltage busbar on this section or the right adjacent low-voltage busbar on this section is 0, and the duration is greater than the discharge time of 15S; or, the left interconnection priority logic signal is "1"; or, the interconnection line power supply mode signal corresponding to the right adjacent low-voltage busbar on this section is 1; or, the pressure plate of the section standby automatic transfer is in the withdrawal position; the device locking mark of the standby automatic transfer safety interlocking device corresponding to the low-voltage busbar on this section, the left adjacent low-voltage busbar or the right adjacent low-voltage busbar on this section is 1; or, during the standby automatic transfer action, a circuit breaker refuses to trip or close; or, the interconnection line circuit breaker corresponding to the low-voltage busbar on this section is in the closed position; or, the right adjacent section circuit breaker is closed.

[0092] Furthermore, the action logic for realizing the right-linked sectional standby automatic transfer operation mode includes: when the right-linked sectional standby automatic transfer operation mode is charged, the right-linked sectional standby automatic transfer mode is started, and after a tripping delay T1, the main transformer secondary main circuit breaker corresponding to the low-voltage side bus of this section and the "right-linked sectional standby mode tripping" message are sent. The main transformer secondary main circuit breaker tripping command is canceled after a 100 millisecond delay. If the secondary main circuit breaker of the main transformer does not trip within 5s of the command, the "right-linked section standby automatic circuit breaker refuses to trip" alarm is issued. If the busbar interlock switch on the low-voltage side of this section does not trip within 5S (the busbar interlock switch is put into operation and the interlock switch position is connected to the device), the "right-linked section standby automatic interlock switch refuses to trip" and "right-linked section standby failure" alarms are issued; after confirming that the corresponding main transformer secondary main circuit breaker and the corresponding interlock switch on the low-voltage side of this section have tripped, after a closing delay T3, the command to close the right adjacent section circuit breaker and the "right section standby closing" message are issued, and the command to close the right adjacent section circuit breaker is canceled after a delay of 100 milliseconds. If the right adjacent section circuit breaker is not closed within 5s of the command, the "right section standby automatic circuit breaker refuses to close" and "right section standby failure" alarms are issued; if it is confirmed that the right adjacent section circuit breaker is closed, the "right section standby success" message is issued.

[0093] Furthermore, 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 interconnecting line circuit breaker signal shows that the interconnecting 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 pressure plate position signal of the section standby automatic transfer function shows that the pressure plate of the section standby automatic transfer function is in the put-in position, the device locking flags of the standby automatic transfer safety interlocking devices 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 signals of the low-voltage side bus of this section and the left adjacent low-voltage side bus are both 1, the interconnecting line power supply mode signal corresponding to the left adjacent low-voltage side bus is 0, 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 interconnecting priority logic signal is 1, then it is determined to adopt the left interconnecting section standby automatic transfer operation mode.

[0094] Among them, the left connection priority logic signal is an external input, that is, when 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 meets the conditions for being put into use. At this time, in order to prevent competition between the two sides, the left connection priority logic signal 1 is input externally.

[0095] The above are the charging conditions of the left-linked sectional standby automatic transfer operation mode. The discharging conditions of the left-linked sectional standby automatic transfer operation mode include:

[0096] The low-voltage busbar on this section or the left adjacent low-voltage busbar on this section meets the no-voltage condition, that is, the busbar voltage logic signal of the low-voltage busbar on this section or the left adjacent low-voltage busbar on this section is 0, and the duration is greater than the discharge time of 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 busbar is 1; the pressure plate of the section standby automatic transfer is in the withdrawal position; or, the device locking mark of the standby automatic transfer safety interlocking device corresponding to the low-voltage busbar on this section, the left adjacent low-voltage busbar or the right adjacent low-voltage busbar is 1; during the standby automatic transfer action, a circuit breaker refuses to trip or close; or, the contact line circuit breaker corresponding to the low-voltage busbar on this section is in the closed position; or, the left adjacent section circuit breaker is closed.

[0097] Furthermore, the action logic for realizing the left-linked sectional standby automatic transfer operation mode includes: when the left-linked sectional standby automatic transfer operation mode is charged, the left-linked sectional standby automatic transfer mode is started, and after a tripping delay T1, the main transformer secondary main circuit breaker corresponding to the low-voltage side bus of this section and the "left-linked sectional standby transfer mode trip" message are sent. The main transformer secondary main circuit breaker trip command is canceled after a 100 millisecond delay. If the secondary main circuit breaker of the main transformer does not trip within 5s of the command, the "left-linked section standby circuit breaker refuses to trip" alarm will be issued. If the busbar interlock switch on the low-voltage side of this section does not trip within 5S (the busbar interlock switch is put into operation and the interlock switch position is connected to the device), the "left-linked section standby interlock switch refuses to trip" and "left-linked section standby failure" alarms will be issued; the secondary main circuit breaker of the main transformer corresponding to the low-voltage side bus of this section and the corresponding interlock switch will trip, and after a closing delay T3, the command to close the left adjacent section circuit breaker and the "left section standby closing" message will be issued, and the command to close the left adjacent section circuit breaker will be cancelled after a delay of 100 milliseconds. If the left adjacent section circuit breaker is not closed within 5s of the closing command, the "left section standby circuit breaker refuses to close" and "left section standby failure" alarms will be issued; if it is confirmed that the left adjacent section circuit breaker is closed, the "left section standby success" message will be issued.

[0098] Furthermore, in step S2, the standby automatic switching safety interlocking device performs a comprehensive logic judgment based on its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes, including:

[0099] 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 adjacent 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 connecting line circuit breaker signal corresponding to the low-voltage side bus of this section shows that the connecting line circuit breaker of the low-voltage side bus of this section is in the open position, the pressure plate position signal of the connecting line standby automatic throwing function shows that the pressure plate of the connecting line standby automatic throwing function is in the put-in position, the device locking flags of the standby automatic throwing safety interlocking devices corresponding to the low-voltage side bus of this section and the low-voltage side bus of the connecting line are both 0, and the bus voltage logic signals of the low-voltage side bus of this section and the low-voltage side bus corresponding to the connecting line are both 1, then it is determined that the connecting line standby automatic throwing operation mode is adopted.

[0100] The above are the charging conditions of the automatic operation mode of the tie line backup, and the discharge conditions are:

[0101] The voltage of the busbar and interconnecting line on the low-voltage side of this section is lower than the busbar no-pressure setting value, and the duration is greater than the discharge time of 15S; or, the left adjacent section circuit breaker is in the closed position; or, the right adjacent section circuit breaker is in the closed position; or, the pressure plate of the interconnecting line standby automatic re-closing function is in the withdrawn position; or, the device locking mark of the standby automatic re-closing safety interlocking device corresponding to the low-voltage side busbar of this section or the low-voltage side busbar of the interconnecting line is 1; or, during the standby automatic re-closing action, a circuit breaker refuses to trip or refuses to close (excluding adjacent device signals); or the main transformer secondary main circuit breaker corresponding to the low-voltage side busbar of this section is open; or, the interconnecting line circuit breaker corresponding to the busbar of this section is in the closed position.

[0102] In the tie line standby automatic switching operation mode, control the closing of the low-voltage busbar on this section and the corresponding tie line circuit breaker. The specific action logic includes: when the tie line standby automatic switching operation charging is completed, the tie line standby automatic switching operation mode is started, and the main transformer secondary main circuit breaker corresponding to the low-voltage busbar on this section and the "tie line standby switching mode tripping" message are sent after a tripping delay of T1+ΔT. The command to trip the main transformer secondary main circuit breaker is canceled after a 100 millisecond delay. If the secondary main circuit breaker of the main transformer does not trip within 5s of the command, the "1DL tie-line standby switch refuses to trip" alarm is issued. If the busbar interlock switch on the low-voltage side of this section does not trip within 5S (the busbar interlock switch is put into operation and the interlock switch position is connected to the device), the "tie-line standby switch refuses to trip" and "tie-line standby switch fails" alarms are issued; after confirming that the secondary main circuit breaker of the main transformer and the corresponding interlock switch are tripped, after a closing delay of T2+ΔT and the left adjacent section circuit breaker and the right adjacent section circuit breaker are both in the open position, the command to close the tie-line circuit breaker corresponding to this section of the busbar and the "tie-line standby automatic closing mode closing" message are issued, and the tie-line circuit breaker closing command is canceled after a 100 millisecond delay. If the tie-line circuit breaker is not closed within 5S of the command, the "tie-line standby switch 2DL refuses to close" and "tie-line standby switch fails" alarms are issued; if it is confirmed that the tie-line circuit breaker is closed, the "tie-line standby switch success" message is issued.

[0103] Since the interconnection line backup automatic switching has the lowest priority, it increases the delay time ΔT (generally 0.3S-0.5S) compared with the incoming line backup automatic switching and the section backup automatic switching.

[0104] Furthermore, the standby automatic switching safety interlocking device performs comprehensive logic judgment according to its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes, including:

[0105] 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 interconnecting line circuit breaker signal shows that the interconnecting 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 pressure plate position signal of the incoming line standby automatic transfer function shows that the pressure plate of the incoming line standby automatic transfer function 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 interconnection priority logic signal is 1, the device locking flags of the standby automatic transfer safety interlocking devices 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 signals of the low-voltage side bus of this section and the right adjacent low-voltage side bus are both 1, then the right incoming line standby automatic transfer operation mode is adopted.

[0106] The above are the charging conditions for the right incoming line standby automatic transfer operation mode, and the discharge conditions are: the bus voltage logic signals of the low-voltage side busbar of this section and the right adjacent busbar are both 0, and the duration is greater than the discharge time of 15S; or, the pressure plate of the incoming line standby automatic transfer function is in the withdrawal position; or, the device lock mark 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 or the right adjacent low-voltage side busbar is 1; or, during the standby automatic transfer operation, a circuit breaker refuses to trip or refuses to close; or, the interconnecting line circuit breaker corresponding to the low-voltage side busbar of this section is in the closed position; or, the right adjacent section circuit breaker is open; or, the left interconnection priority logic signal is "1".

[0107] Furthermore, the action logic for realizing the right incoming line standby automatic switching operation mode includes: when the right incoming line standby automatic switching mode is charged, the right incoming line standby automatic switching mode is started, and after a tripping delay T1, the main transformer secondary main circuit breaker corresponding to the low-voltage side bus of this section and the "right incoming line standby switching mode trip" message are sent. The main transformer secondary main circuit breaker trip command is canceled after a 100 millisecond delay. If the secondary main circuit breaker of the main transformer does not trip within 5s of the command, the "right incoming line standby throw 1DL refuses to trip" message is sent. If the busbar interlock switch on the low-voltage side of this section does not trip within 5S (the busbar interlock switch is put into operation and the interlock switch position is connected to the device), the "right incoming line standby throw interlock switch refuses to trip" and "right incoming line standby throw failed" alarms are sent; after confirming that the secondary main circuit breaker of the main transformer and the corresponding interlock switch have tripped, the "right incoming line standby throw trip and interlock switch success" signal is sent to the right adjacent standby automatic throw safety interlock device (Note: this device is defined as the "right interlock opening" signal, and the opposite device is defined as the "left interlock opening" signal). Then, the busbar on the low-voltage side of this section maintains the status quo. After a delay of T2, if the three-phase busbar voltage is judged to be normal, the "right incoming line standby throw success" message is sent; otherwise, the "right incoming line standby throw failure" message is sent.

[0108] Furthermore, 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 interconnecting line circuit breaker signal shows that the interconnecting 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 pressure plate position signal of the incoming line standby automatic transfer function shows that the pressure plate of the incoming line standby automatic transfer function 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 adjacent section circuit breaker is in the closed position and the left interconnection priority logic signal is 1, the device locking flags of the standby automatic transfer safety interlocking devices 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 signals of the low-voltage side bus of this section and the left adjacent low-voltage side bus are both 1, then the left incoming line standby automatic transfer operation mode is adopted.

[0109] The above are the charging conditions for the left incoming line standby automatic transfer operation mode, and the discharge conditions include: the bus voltage logic signals of the low-voltage side busbar of this section and the left adjacent low-voltage side busbar are both 0, and the duration is greater than the discharge time of 15S; or, the pressure plate of the incoming line standby automatic transfer function is in the exit position; or, the device lock mark 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 or the right adjacent low-voltage side busbar is 1; or, during the standby automatic transfer operation, a circuit breaker refuses to trip or refuses to close; or, the corresponding interconnecting line circuit breaker of the low-voltage side busbar of this section is in the closed position; or, the low-voltage side busbar of this section and the left adjacent section circuit breaker are open; or, the right interconnection priority logic signal is "1".

[0110] The action logic for realizing the left incoming line standby automatic switching operation mode includes: when the left incoming line standby automatic switching mode is charged, the left incoming line standby automatic switching mode is started, and after a tripping delay T1, the main transformer secondary main circuit breaker corresponding to the low-voltage side bus of this section and the "left incoming line standby switching mode tripping" message are sent. The main transformer secondary main circuit breaker tripping command is canceled after a 100 millisecond delay. If the secondary main circuit breaker of the main transformer does not trip within 5s after the command is sent, the "left incoming line standby 1DL refuses to trip" message will be sent. If the busbar interlock switch on the low-voltage side of this section does not trip within 5S (the busbar interlock switch is put into operation and the interlock switch position is connected to the device), the "left incoming line standby interlock switch refuses to trip" and "left incoming line standby failure" alarms will be sent; after confirming that the secondary main circuit breaker of the main transformer and the corresponding interlock switch have tripped, the "left incoming line standby trip and interlock switch success" signal will be sent to the left adjacent standby automatic safety interlock device (Note: this device is defined as the "left interlock out" signal, and the opposite device is defined as the "right interlock in" signal). Then, the busbar on the low-voltage side of this section maintains the status quo. After a delay of T2, if the three-phase busbar voltage is judged to be normal, the "left incoming line standby success" message will be sent; otherwise, the "left incoming line standby failure" message will be sent.

[0111] Furthermore, the standby automatic switching safety interlocking device performs comprehensive logic judgment according to its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes, including:

[0112] 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 sub-main circuit breaker signal corresponding to the low-voltage side bus of this section shows that the main transformer sub-main circuit breaker is in the tripped position, the interconnecting line circuit breaker signal corresponding to the low-voltage side bus of this section shows that the interconnecting line circuit breaker is in the open position, the pressure plate position signal of the incoming line standby automatic function shows that the pressure plate of the incoming line standby automatic function is in the engaged position, the device locking flags of the standby automatic safety interlocking devices 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 signals of the low-voltage side bus of this section and the right adjacent low-voltage side bus are both 1, then the main transformer standby automatic operation mode with the right adjacent section circuit breaker in the closed position is adopted.

[0113] The pressure plates for the incoming line standby automatic re-throwing function include soft pressure plates and hard pressure plates. If the soft pressure plate is put into operation, the main transformer sub-circuit breaker corresponding to the low-voltage side bus of this section meets the pressure condition; if the soft pressure plate is not put into operation, it will not be detected whether the main transformer sub-circuit breaker corresponding to the low-voltage side bus of this section has pressure.

[0114] The above are the charging conditions of the main transformer standby automatic transfer operation mode when the right adjacent section circuit breaker is closed, and the discharge conditions include: the bus voltage logic signals of the low-voltage side busbar of this section and the right adjacent low-voltage side busbar are both 0, and the duration is greater than the discharge time 15S; or, the soft pressure plate is put into operation, and the voltage of the main transformer secondary main circuit breaker corresponding to the low-voltage side busbar of this section is lower than the line no-pressure setting value, and the duration is greater than the discharge time 15S; or, the right adjacent section circuit breaker is manually tripped; or, the pressure plate of the incoming line standby automatic transfer function is in the exit position; or, the device locking mark 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 or the right adjacent low-voltage side busbar is 1; during the standby automatic transfer action, there is a circuit breaker that refuses to trip or refuses to close (including the adjacent device opening signal); or, the main transformer secondary main circuit breaker corresponding to the low-voltage side busbar of this section is closed; or, the interconnecting line circuit breaker corresponding to the low-voltage side busbar of this section is in the closed position; or, the right adjacent section circuit breaker protection trips.

[0115] The action logic of the main transformer standby automatic operation mode when the right adjacent section circuit breaker is closed includes: when the charging conditions are completed, the "left incoming line standby tripping and interlocking switch success" signal of the right adjacent standby automatic safety interlocking device is received (Note: this device is defined as the "right connection opening" signal, and the opposite device is defined as the "left connection opening" signal), and after a closing delay T2, the command to close the main transformer secondary main circuit breaker corresponding to the low-voltage side bus of this section and the "main transformer standby automatic mode closing when the right adjacent section circuit breaker is closed" message are sent, and the command to close the main transformer secondary main circuit breaker is canceled after a 100-ms delay. If the main transformer secondary main circuit breaker is not closed within 5S of issuing the command, the alarms of "main transformer standby automatic switching refused to close when the right adjacent section circuit breaker was closed" and "main transformer standby automatic switching failed when the right adjacent section circuit breaker was closed" will be issued; if it is confirmed that the main transformer secondary main circuit breaker is closed, the message of "main transformer standby automatic switching succeeded when the right adjacent section circuit breaker was closed" will be issued.

[0116] Furthermore, 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 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 tripped position, the interconnecting line circuit breaker signal corresponding to the low-voltage side bus of this section shows that the interconnecting line circuit breaker is in the open position, the pressure plate position signal of the incoming line standby automatic throwing function shows that the pressure plate of the incoming line standby automatic throwing function is in the put-in position, the device locking flags of the standby automatic throwing safety interlocking devices 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 signals of the low-voltage side bus of this section and the left adjacent low-voltage side bus are both 1, then the main transformer standby automatic throwing operation mode with the left adjacent section circuit breaker in the closed position is adopted.

[0117] The pressure plates for the incoming line standby automatic re-throwing function include soft pressure plates and hard pressure plates. If the soft pressure plate is put into operation, the main transformer sub-circuit breaker corresponding to the low-voltage side bus of this section meets the pressure condition; if the soft pressure plate is not put into operation, it will not be detected whether the main transformer sub-circuit breaker corresponding to the low-voltage side bus of this section has pressure.

[0118] The above are the charging conditions of the main transformer standby automatic transfer operation mode when the left adjacent section circuit breaker is closed, and the discharge conditions include: the bus voltage logic signals of the low-voltage side busbar of this section and the left adjacent low-voltage side busbar voltage are both 0, and the duration is greater than the discharge time 15S; or, when the soft pressure plate is put into operation, the voltage of the main transformer secondary main circuit breaker corresponding to the low-voltage side busbar of this section is lower than the line no-pressure setting value, and the duration is greater than the discharge time 15S; or, the left adjacent section circuit breaker is manually tripped; or, the pressure plate of the incoming line standby automatic transfer function is in the exit position; or, the device locking mark 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 or the right adjacent low-voltage side busbar is 1; or, during the standby automatic transfer action, a circuit breaker refuses to trip or refuses to close (including adjacent device signals); or, the main transformer secondary main circuit breaker corresponding to the low-voltage side busbar of this section is closed; or, the interconnecting line circuit breaker corresponding to the low-voltage side busbar of this section is in the closed position; or, the left adjacent section circuit breaker protection trips.

[0119] The action logic of the main transformer standby automatic operation mode when the left adjacent section circuit breaker is closed includes: when the charging conditions are completed, the "right incoming line standby tripping and interlocking switch success" signal of the left adjacent standby automatic safety interlocking device is received (Note: this device is defined as the "left link opening" signal, and the opposite device is defined as the "right link opening" signal), and after a closing delay T2, the command to close the main transformer secondary main circuit breaker corresponding to the low-voltage side bus of this section and the "main transformer standby automatic mode closing when the left adjacent section circuit breaker is closed" message are sent, and the command to close the main transformer secondary main circuit breaker is canceled after a 100-ms delay. If the main transformer secondary main circuit breaker is not closed within 5S of issuing the closing command, the alarms of "main transformer standby automatic closing refused to close when the left adjacent section circuit breaker was closed" and "main transformer standby automatic closing failed when the left adjacent section circuit breaker was closed" will be issued; if it is confirmed that the main transformer secondary main circuit breaker is closed, the message of "main transformer standby automatic closing refused to close and standby closing was successful when the left adjacent section circuit breaker was closed" will be issued.

[0120] Furthermore, under the non-main transformer power supply mode, 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 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 open position, the connecting line circuit breaker signal corresponding to the low-voltage side bus of this section shows that the connecting line circuit breaker is in the closed position, the device locking marks of the standby automatic safety interlocking devices of the low-voltage side bus of this section and the low-voltage side bus corresponding to the connecting line are both 0, the pressure plate position signal of the connecting line standby automatic function shows that the pressure plate of the connecting line standby automatic function is in the engaged position, and the bus voltage logic signals of the low-voltage side bus of this section and the low-voltage side bus corresponding to the connecting line are both 1, then the connecting line main transformer standby automatic operation mode is adopted.

[0121] The above are the charging conditions for the automatic switching operation mode of the main transformer of the interconnection line, and the discharge conditions include: the bus voltage logic of the low-voltage side busbar of this section and the low-voltage side busbar corresponding to the interconnection line are both 0, and the duration is greater than the discharge time of 15S; or, the left adjacent section circuit breaker is in the closed position; or, the right adjacent section circuit breaker is in the closed position; the pressure plate of the automatic switching function of the interconnection line is in the exit position; the device locking mark of the automatic switching safety interlocking device of the low-voltage side busbar of this section or the low-voltage side busbar corresponding to the interconnection line is 1; or, during the automatic switching operation, a circuit breaker refuses to trip or close (excluding adjacent device signals); or, the main transformer secondary main circuit breaker corresponding to the low-voltage side busbar of this section is closed; or, the interconnection line circuit breaker corresponding to the low-voltage side busbar of this section is in the open position.

[0122] The action logic of the automatic operation mode of the main transformer and standby transformer of the tie line includes: after a tripping delay T1, the tie line circuit breaker corresponding to the low-voltage side bus of this section and the "tie line main transformer and standby transformer automatic mode trip" message are sent. The order to trip the tie line circuit breaker is cancelled after a 100-ms delay. If the tie line circuit breaker does not trip within 5s of the command, the "tie line main transformer and standby transformer automatic transfer refuses to trip" is issued. If the bus inter-cut switch on the low-voltage side of this section does not trip within 5S (the bus inter-cut switch is put into operation and the inter-cut switch position is connected to the device), the "tie line main transformer and standby transformer automatic transfer inter-cut switch refuses to trip" and "tie line main transformer and standby transformer automatic transfer failure" alarms are issued; after confirming that the tie line circuit breaker and the corresponding inter-cut switch are tripped, after a closing delay T2, the order to close the main transformer secondary main circuit breaker corresponding to the low-voltage side bus of this section and the "tie line main transformer and standby transformer automatic transfer mode closing" message are issued, and the order to close the main transformer secondary main circuit breaker is cancelled after a 100-ms delay. If the main transformer secondary main circuit breaker is not closed within 5S of the main transformer secondary main circuit breaker closing command, the "main transformer secondary main circuit breaker refuses to close" and "interconnection line main transformer standby automatic transfer failed" alarms will be issued; if it is confirmed that the main transformer secondary main circuit breaker is closed, the "interconnection line main transformer standby automatic transfer successful" message will be issued.

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

[0124] When the three-phase voltage of bus section I on the low-voltage side is normal and the bus live indicator is under pressure, the bus voltage logic is "1". When the three-phase voltage of the bus is zero and the bus live indicator is under no pressure, the bus voltage logic is "0"; and the device locking flag of the backup automatic safety interlocking device of bus section I on the low-voltage side is 0, it is a valid condition and the low-voltage side bus interconnection line A0 and active lines A1~A4 of this section will be tripped without delay.

[0125] When the three-phase voltage of bus section II on the low-voltage side is normal and the bus live indicator has pressure, the bus voltage logic is "1". When the three-phase voltage of the bus is zero and the bus live indicator has no pressure, the bus voltage logic is "0"; and the device locking mark of the backup automatic safety interlocking device of bus section II on the low-voltage side is 0, it is a valid condition and the low-voltage side bus interconnection line B0 and active lines B1~B4 of this section will be tripped without delay.

[0126] When the three-phase voltage of bus section III on the low-voltage side is normal and the bus live indicator has pressure, the bus voltage logic is "1". When the three-phase voltage of the bus is zero and the bus live indicator has no pressure, the bus voltage logic is "0"; and the device locking flag of the backup automatic safety interlocking device of bus section I on the low-voltage side is 0, it is a valid condition and the exit will not delay the tripping of the bus interconnection line C0 and active lines C1~C4 of this section.

[0127] In some embodiments, a backup power automatic switching control system based on voltage dual criteria is also provided, comprising at least two substations, wherein the substations include at least two main transformers, and at least two main transformers are connected in sections using a single busbar, and each section of the low-voltage side busbar is provided with a connecting line to connect with the low-voltage side busbars of other substations, and each section of the low-voltage side busbar is provided with a backup automatic switching safety interlocking device;

[0128] The standby automatic switching 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 state signal and send it to other standby automatic switching safety interlocking devices in the substation where it is located and the standby automatic switching safety interlocking devices corresponding to other substations;

[0129] The standby automatic switching safety interlocking device is also used to perform comprehensive logic judgment based on its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes.

[0130] The above-mentioned embodiments provide a method and system for automatically switching a backup power supply based on voltage dual criteria, which have at least the following beneficial effects:

[0131] (1) Each section of the low-voltage side busbar is equipped with a backup automatic safety interlocking device, and the adjacent backup automatic safety interlocking devices can exchange signals with each other. The voltage signal, protection action signal and switch signal are used to perform comprehensive logical judgment to achieve reliable, accurate and rapid exit tripping and closing of the associated circuit breakers, and quickly restore the power supply of this section of the busbar.

[0132] (2) Abandoning the existing current as a 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 locking;

[0133] (3) Adjacent backup automatic safety interlocking devices can exchange signals and interlock signals to avoid competition between different devices or abnormal closing of adjacent busbars;

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

[0135] (5) The method proposed in the above embodiment only involves the newly built busbar during debugging, and has no impact on the previously built busbar, which is convenient for the expansion of the substation;

[0136] (6) The method proposed in the above embodiment is applicable to the working condition of the substation with tie line. On the basis of the original standby automatic switching action logic which only has the incoming line standby automatic switching function and the bridge standby automatic switching function, the tie line standby automatic switching scheme is adopted to realize the mutual standby between substations;

[0137] (7) The method provided in the above embodiment can prevent the occurrence of islanding phenomenon and asynchronous closing phenomenon. When any low-voltage side bus of the substation loses pressure temporarily or permanently, the active line connected to the bus can be reliably disconnected, effectively improving the reliability of the system.

[0138] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for automatically switching a backup power supply based on voltage dual criteria, characterized in that: Applied to a substation, the substation includes at least two main transformers, the at least two main transformers are connected in sections using a single busbar, each section of the low-voltage side busbar is provided with a connecting line to connect with the low-voltage side busbars of other substations, and each section of the low-voltage side busbar is provided with a standby automatic safety interlocking device; the method includes: The standby automatic switching safety interlocking device collects the voltage signal, protection action signal and switch signal of the corresponding low-voltage side bus, makes judgments based on the voltage signal, protection action signal and switch signal of the low-voltage side bus, generates a logic state signal and sends it to other standby automatic switching safety interlocking devices in the substation where it is located and the standby automatic switching safety interlocking devices corresponding to other substations; The standby automatic switching safety interlocking device performs comprehensive logic judgment based on its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes.

2. The method according to claim 1, characterized in that The protection action signal includes the main transformer protection action signal and the tie line protection action signal; the switch signal includes the main transformer secondary main circuit breaker manual opening signal, the tie line circuit breaker manual opening signal and the section circuit breaker position status; the logic state signal includes the device locking flag; The standby automatic safety interlocking device makes a judgment based on the protection action signal and the switch signal to generate a logic state signal, including: The standby automatic switching safety interlocking device determines whether the main transformer protection action occurs according to the main transformer protection action signal, and when the main transformer protection action occurs, the standby automatic switching safety interlocking device is locked; The standby automatic switching safety interlocking device determines whether the tie line protection action occurs according to the tie line protection action signal. When the tie line protection action occurs and the low-voltage side busbar of this section fails, the standby automatic switching safety interlocking device is locked; The standby automatic switching safety interlocking device determines whether the main transformer secondary circuit breaker is manually opened and the tie line circuit breaker is manually opened according to the manual opening signal of the main transformer secondary circuit breaker and the manual opening signal of the tie line circuit breaker. When the main transformer secondary circuit breaker is manually opened or the tie line circuit breaker is manually opened, the standby automatic switching safety interlocking device is locked; After the standby automatic safety interlocking device is locked, the device locking flag is set to 1. If the standby automatic safety interlocking device is not locked, the device locking flag is 0.

3. The method according to claim 2, characterized in that The logic state signal also includes a bus voltage logic signal; The standby automatic switching safety interlocking device makes a judgment based on the voltage signal of the low-voltage side busbar and generates a logic state signal, including: Collect the low-voltage side bus live indicator signal, and perform consistency check 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, generate a bus voltage logic signal 1; when the voltage signal and the low-voltage side bus live indicator signal are both abnormal, generate a bus voltage logic signal 0; The method further comprises: When the voltage signal is normal and the low-voltage side busbar energized indicator signal is abnormal, or when the voltage signal is abnormal and the low-voltage side busbar energized indicator signal is normal, an alarm signal is generated.

4. The method according to claim 3, characterized in that With left and right as logical relative positions, each section of low-voltage side busbar includes a left adjacent low-voltage side busbar and a right adjacent low-voltage side busbar, and is respectively provided with a left adjacent section circuit breaker and a right adjacent section circuit breaker; The switch signal includes the main transformer sub-circuit breaker signal, the tie line circuit breaker signal, the left adjacent section circuit breaker signal, the right adjacent section circuit breaker signal, the pressure plate position signal of the section standby automatic switching function, the pressure plate position signal of the tie line standby automatic switching function, and the pressure plate position signal of the incoming line standby automatic switching function; The logic state signal also includes a tie line power supply mode signal; The standby automatic safety interlocking device makes a judgment based on the switch signal and generates a logic state signal, including: The standby automatic safety interlocking device determines whether the low-voltage side busbar of this 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 busbar of this section is powered by the tie line, and the tie line power supply mode signal is set to 1; otherwise, the tie line power supply mode signal is set to 0.

5. The method according to claim 4, characterized in that The standby automatic switching safety interlocking device performs comprehensive logic judgment according to its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes, including: Under the main transformer power supply mode, if the main transformer sub-main circuit breaker signal corresponding to the low-voltage side bus of this section shows that the main transformer sub-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 pressure plate position signal of the section standby automatic transfer function shows that the pressure plate of the section standby automatic transfer function is in the put-in position, the device locking flags of the standby automatic transfer safety interlocking devices 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 signals of the low-voltage side bus of this section and the right adjacent low-voltage side bus are all 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, then it is determined to adopt the right-linked section standby automatic transfer operation mode; 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 interconnecting line circuit breaker signal shows that the interconnecting 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 pressure plate position signal of the section standby automatic transfer function shows that the pressure plate of the section standby automatic transfer function is in the put-in position, the device locking flags of the standby automatic transfer safety interlocking devices 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 signals of the low-voltage side bus of this section and the left adjacent low-voltage side bus are both 1, the interconnecting line power supply mode signal corresponding to the left adjacent low-voltage side bus is 0, 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 interconnecting priority logic signal is 1, then it is determined that the left interconnecting section standby automatic transfer operation mode is adopted.

6. The method according to claim 5, characterized in that The left contact priority logic signal and the right contact priority logic signal are external inputs; In the right-connected sectional standby automatic switching operation mode, control the closing of the right adjacent sectional circuit breaker; In the left-linked section standby automatic switching operation mode, the left adjacent section circuit breaker is controlled to close.

7. The method according to claim 4, characterized in that The standby automatic switching safety interlocking device performs comprehensive logic judgment according to its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes, 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 sub-main circuit breaker signal corresponding to the low-voltage side bus of this section shows that the main transformer sub-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 pressure plate position signal of the tie-line standby automatic function shows that the pressure plate of the tie-line standby automatic function is in the switched-on position, the device locking flags of the standby automatic safety interlocking devices corresponding to the low-voltage side bus of this 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 this section and the low-voltage side bus corresponding to the tie line are both 1, then it is determined that the tie-line standby automatic operation mode is adopted; In the automatic standby operation mode of the interconnection line, the low-voltage busbar of this section and the corresponding interconnection line circuit breaker are controlled to close.

8. The method according to claim 5, characterized in that The standby automatic switching safety interlocking device performs comprehensive logic judgment according to its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes, including: In the main transformer power supply mode, if the main transformer sub-main circuit breaker signal corresponding to the low-voltage side busbar of this section shows that the main transformer sub-main circuit breaker is in the closed position, the interconnecting line circuit breaker signal shows that the interconnecting 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 pressure plate position signal of the incoming line standby automatic function shows that the pressure plate of the incoming line standby automatic function 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 interconnection priority logic signal is 1, the device locking flags of the standby automatic safety interlocking devices 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 signals 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 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 busbar of this section shows that the main transformer secondary main circuit breaker is in the closed position, the interconnecting line circuit breaker signal shows that the interconnecting 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 pressure plate position signal of the incoming line standby automatic transfer function shows that the pressure plate of the incoming line standby automatic transfer function 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 interconnection priority logic signal is 1, the device locking flags of the standby automatic transfer safety interlocking devices 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 signals of the low-voltage side busbar of this section and the left adjacent low-voltage side busbar are both 1, then the left incoming line standby automatic transfer operation mode is adopted.

9. The method according to claim 4, characterized in that The standby automatic switching safety interlocking device performs comprehensive logic judgment according to its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes, including: 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 sub-main circuit breaker signal corresponding to the low-voltage side bus of this section shows that the main transformer sub-main circuit breaker is in the tripped position, the tie line circuit breaker signal corresponding to the low-voltage side bus of this section shows that the tie line circuit breaker is in the open position, the pressure plate position signal of the incoming line standby automatic function shows that the pressure plate of the incoming line standby automatic function is in the put-in position, the device locking flag of the standby automatic 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 signals 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 operation mode with the right adjacent section circuit breaker in the closed position is adopted; 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 sub-main circuit breaker signal corresponding to the low-voltage side bus of this section shows that the main transformer sub-main circuit breaker is in the tripped position, the tie line circuit breaker signal corresponding to the low-voltage side bus of this section shows that the tie line circuit breaker is in the open position, the pressure plate position signal of the incoming line standby automatic function shows that the pressure plate of the incoming line standby automatic function is in the put-in position, the device locking flags of the standby automatic safety interlocking devices 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 signals 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 operation mode with the left adjacent section circuit breaker in the closed position is adopted; In the non-main transformer power supply mode, 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 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 open position, the connecting line circuit breaker signal corresponding to the low-voltage side bus of this section shows that the connecting line circuit breaker is in the closed position, the device locking marks of the standby automatic safety interlocking devices of the low-voltage side bus of this section and the low-voltage side bus corresponding to the connecting line are both 0, the pressure plate position signal of the connecting line standby automatic function shows that the pressure plate of the connecting line standby automatic function is in the engaged position, the bus voltage logic signals of the low-voltage side bus of this section and the low-voltage side bus corresponding to the connecting line are both 1, then the connecting line main transformer standby automatic operation mode is adopted.

10. A backup power supply automatic switching control system based on voltage dual criteria, characterized in that: It includes at least two substations, each of which includes at least two main transformers, and at least two main transformers are connected in sections using a single busbar. Each section of the low-voltage side busbar is provided with a connecting line to connect with the low-voltage side busbars of other substations, and each section of the low-voltage side busbar is equipped with a standby automatic safety interlocking device; The standby automatic switching 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 state signal and send it to other standby automatic switching safety interlocking devices in the substation where it is located and the standby automatic switching safety interlocking devices corresponding to other substations; The standby automatic switching safety interlocking device is also used to perform comprehensive logic judgment based on its own voltage signal, protection action signal, switch signal and received logic state signal to determine the standby automatic switching operation mode under different power supply modes.

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