Automatic switching method and device of direct current power supply

Abstract

The invention discloses an automatic switching method and device for a DC power supply, and the method comprises the steps: obtaining the potential difference of two DC buses at different sampling moments through a voltage detection module, and obtaining a target voltage according to the potential difference; and if it is monitored that the bus battery pack voltage of one section of direct-current bus is abnormal based on the target voltage, controlling a contactor to pull in so as to make the two sections of direct-current buses parallel, thereby using a normal power supply to supply power to the abnormal direct-current bus. According to the invention, a normal power supply is automatically and quickly used to replace an abnormal power supply to supply power to the DC bus with abnormal power supply, the current situation of passive and hysteresis operation of personnel is changed, uninterrupted power supply is realized, the power failure time is reduced, loss caused by power failure is avoided, the user experience is improved, and the application prospect is wide. According to the invention, automatic switching of the dual power supplies during fault, maintenance and operation mode adjustment is realized, the operation of operation and maintenance personnel on equipment is reduced, and the safety coefficient of operation is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid power supply, and in particular to an automatic switching method and device for a direct current power supply. Background Art

[0002] In the prior art, most of the dual-configuration DC system substations are in an unmanned state. In the unmanned state, when the DC power supply of one DC system is abnormal, it is difficult for operators and professionals to arrive in time to repair it. If the abnormal DC power supply is abnormal for a long time, it will affect the stable operation of the power grid. Summary of the invention

[0003] Based on this, it is necessary to propose a method and device for automatically switching a DC power supply to address the technical problem that the DC power supply abnormality in the prior art cannot be repaired in time.

[0004] The present application provides an automatic switching method for a DC power supply, which is applied to a main control module in an automatic switching device for a DC power supply. The automatic switching device for a DC power supply is applied to a dual-configuration DC system substation. The dual-configuration DC system substation includes two DC power supplies, each of which includes a first section of a DC bus and a second section of a DC bus powered by different power supplies. The first section of the DC bus and the second section of the DC bus can be connected or disconnected through a contactor. The first section of the DC bus and the second section of the DC bus both include a positive potential, a negative potential, and a zero potential. The automatic switching device for the DC power supply includes a main control module, and a voltage detection module and a contactor control module electrically connected to the main control module. The voltage detection module is connected to the first section of the DC bus and the second section of the DC bus, respectively, and the contactor control module is connected to the contactor. The automatic switching method for the DC power supply includes:

[0005] A voltage detection module is used to obtain a first potential difference of a first section of the DC bus and a second potential difference of a second section of the DC bus at different sampling times, and a target voltage at different sampling times is obtained according to the first potential difference and the second potential difference, wherein the target voltage includes a bus battery pack voltage of each of the two sections of the DC bus, and the bus battery pack voltage is a potential difference between a positive potential and a negative potential of the same section of the DC bus;

[0006] If the bus battery pack voltage of any section of the DC bus is detected to be abnormal based on the target voltage at different sampling times, the contactor control module controls the contactor to be attracted to parallel the first section of the DC bus and the second section of the DC bus, so that the normal power supply can be used to power the DC bus with abnormal bus battery pack voltage, wherein the normal power supply is the power supply corresponding to the DC bus with normal bus battery pack voltage.

[0007] The present application also provides an automatic switching device for a DC power supply, which is applied to a DC system substation with a dual configuration, and includes a main control module, and a voltage detection module and a contactor control module electrically connected to the main control module;

[0008] The voltage detection module is connected to the first section of the DC bus and the second section of the DC bus respectively;

[0009] A main control module is used to perform power switching according to any of the above-mentioned automatic switching methods of DC power supply.

[0010] This application determines whether the power supply of the DC bus is normal by monitoring the target voltage of the two sections of the DC bus in the dual configuration DC system substation. When it is determined that the power supply of one section of the DC bus is abnormal, the normal power supply is used to replace the abnormal power supply to automatically switch the power supply of the abnormal DC bus, so that the power supply to the DC bus with abnormal voltage is quickly restored, and the normal operation of the power grid is restored. This application will change the current situation of passive and lagging operation of personnel through the automatic switching of DC power supply, realize uninterrupted power supply, reduce power outage time, avoid losses caused by power outages, and improve the efficiency of operation and maintenance. This application can realize the automatic switching of dual power supplies during failure, maintenance and operation mode adjustment, reduce the operation of equipment by operation and maintenance personnel, and improve the safety factor of operation. This application improves power supply reliability, reduces complaints caused by frequent power outages, improves user experience, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0012] in:

[0013] Figure 1 This is a flow chart of a method for automatically switching a DC power supply in one embodiment of the present application;

[0014] Figure 2 This is a structural block diagram of an automatic switching device for a DC power supply in one embodiment of the present application;

[0015] Figure 3 A circuit diagram of a contactor control module in one embodiment of the present application;

[0016] Figure 4 This is a circuit diagram of a contactor manual control module in one embodiment of the present application.

[0017] Figure 5 A circuit diagram of a voltage detection unit in one embodiment of the present application;

[0018] Figure 6 A circuit diagram of a main control module in one embodiment of the present application;

[0019] Figure 7 A circuit diagram of a power module in one embodiment of the present application;

[0020] Figure 8 This is a structural block diagram of an automatic switching device for a DC power supply in another embodiment of the present application. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In the prior art, most of the dual-configuration DC system substations are in an unmanned state. In the unmanned state, when the DC power supply of one DC system is abnormal, it is difficult for operators and professionals to arrive in time to repair it. If the abnormal DC power supply is abnormal for a long time, it will affect the stable operation of the power grid.

[0023] In addition, if the charging device fails or is set incorrectly, and there is no one on duty or the alarm is not handled in a timely manner, it is easy to cause the power supply to fail to charge normally for a long time and suffer capacity loss, or even total capacity loss, affecting the safe and stable operation of the power grid.

[0024] If the DC bus voltage difference and other conditions do not meet the requirements, operating the bus tie switch may cause a huge impact current that threatens the life safety of the operator and causes damage to the battery.

[0025] Based on this, the present application provides a method and device for automatically switching a DC power supply.

[0026] like Figure 1As shown, in one embodiment, a method for automatically switching a DC power supply is provided, which is applied to a main control module in an automatic switching device of a DC power supply. The automatic switching device of the DC power supply is applied to a dual-configuration DC system substation. The dual-configuration DC system substation includes two DC power supplies, each of which includes a first section of a DC bus and a second section of a DC bus powered by different power supplies. The first section of the DC bus and the second section of the DC bus can be connected or disconnected through a contactor. The first section of the DC bus and the second section of the DC bus both include a positive potential, a negative potential and a zero potential. The automatic switching device of the DC power supply includes a main control module, and a voltage detection module and a contactor control module electrically connected to the main control module;

[0027] The voltage detection module is connected to the first section of the DC bus and the second section of the DC bus respectively;

[0028] The automatic switching method of the DC power supply comprises:

[0029] S100: Using a voltage detection module to obtain a first potential difference of a first section of the DC bus and a second potential difference of a second section of the DC bus at different sampling times, and calculating target voltages at different sampling times based on the first potential difference and the second potential difference, wherein the target voltage includes the bus battery pack voltages of the two sections of the DC bus, and the bus battery pack voltage is the potential difference between the positive potential and the negative potential of the same section of the DC bus.

[0030] Specifically, the dual configuration DC system substation includes two DC power supplies, each of which includes a section of DC bus, that is, the first DC power supply includes a first section of DC bus (that is, section I DC bus), and the second DC power supply includes a second section of DC bus (that is, section II DC bus). Under normal circumstances, the first section of DC bus and the second section of DC bus are powered by different power supplies, and the two sections of DC bus are independent of each other. The power supply supplies power to the DC bus, and the AC charger charges the power supply. If the AC charger supplies power abnormally or the power supply is abnormal, the voltage of the corresponding DC bus is abnormal.

[0031] The power supply is a DC power supply, for example, a battery pack.

[0032] The first section of the DC bus and the second section of the DC bus can be connected or disconnected through a contactor. If the first section of the DC bus and the second section of the DC bus are connected through a contactor, the two share the same power supply. If the first section of the DC bus and the second section of the DC bus are disconnected through a contactor, the two correspond to different power supplies and are powered by different power supplies.

[0033] The on and off of the contactor is controlled by the automatic switching device of the DC power supply.

[0034] The contactor may be part of the automatic switching device of the DC power supply or may be independent of the automatic switching device of the DC power supply.

[0035] The automatic switching device of the DC power supply includes a main control module, and a voltage detection module and a contactor control module connected to the main control module. The contactor control module is connected to the contactor. The voltage detection module is respectively connected to the detection points corresponding to the positive potential, negative potential and zero potential contained in the first section of the DC bus and the second section of the DC bus, and is used to detect a first potential difference between the first section of the DC bus and a second potential difference between the second section of the DC bus.

[0036] The first potential difference is the difference between the positive potential, negative potential and zero potential of the first section of the DC bus. The second potential difference is the difference between the positive potential, negative potential and zero potential of the second section of the DC bus. The positive potential, negative potential and zero potential correspond to three voltage detection points of the DC bus. For example, under normal circumstances, the positive potential is +110v, the negative potential is -110v, and the zero potential is 0v.

[0037] The automatic switching method of the DC power supply of this embodiment is applied to the main control module. The main control module can use the voltage detection module to obtain the first potential difference and the second potential difference, and calculate or obtain the target voltage according to the first potential difference and the second potential difference.

[0038] More specifically, the first potential difference includes the difference between the positive potential, negative potential and zero potential of the first section of the DC bus; the voltage difference or difference between the positive potential and the negative potential of the first section of the DC bus is called the I section bus battery pack voltage (i.e., the bus battery pack voltage of the first section of the DC bus). The second potential difference includes the difference between the positive potential, negative potential and zero potential of the second section of the DC bus; the voltage difference or difference between the positive potential and the negative potential of the second section of the DC bus is called the II section bus battery pack voltage (i.e., the bus battery pack voltage of the second section of the DC bus). The bus battery pack voltage belongs to the potential difference or voltage difference.

[0039] The target voltage includes the bus battery group voltage of the first section DC bus and the bus battery group voltage of the second section DC bus.

[0040] S200: If the bus battery pack voltage of any section of the DC bus is detected to be abnormal based on the target voltage at different sampling times, the contactor control module is used to control the contactor to be attracted to parallel the first section of the DC bus and the second section of the DC bus, so that the normal power supply can be used to power the DC bus with the abnormal bus battery pack voltage, wherein the normal power supply is the power supply corresponding to the DC bus with a normal bus battery pack voltage.

[0041] Specifically, the main control module can obtain the target voltage at different sampling times through the voltage detection module. According to the target voltage at different sampling times, the main control module can determine whether the bus battery pack voltages of the first DC bus segment and the second DC bus segment are abnormal. The bus battery pack voltage abnormality includes, for example, a continuous decrease in the bus battery pack voltage.

[0042] If the bus battery voltage of one of the two DC buses is abnormal, and the bus battery voltage of the other DC bus is normal, it means that the power supply of one section of the DC bus is abnormal, and the main control module can control the contactor to pull in through the contactor control module, thereby controlling the two sections of the DC bus to be parallel. Specifically, the two sections of the DC bus are parallel means that the two sections of the DC bus share the same power supply.

[0043] More specifically, if the DC bus with abnormal bus battery pack voltage is the first section of the DC bus, then the DC bus with normal bus battery pack voltage is the second section of the DC bus; if the DC bus with abnormal bus battery pack voltage is the second section of the DC bus, then the DC bus with normal bus battery pack voltage is the first section of the DC bus.

[0044] Under normal circumstances, the first power supply supplies power to the first section of the DC bus, and the second power supply supplies power to the second section of the DC bus. If the first power supply is abnormal, it will cause the bus battery pack voltage of the first section of the DC bus to be abnormal. Therefore, it is necessary to connect the first section of the DC bus and the second section of the DC bus in parallel through a contactor, so that the second power supply replaces the first power supply to supply power to the first section of the DC bus, and the second power supply also supplies power to the second section of the DC bus.

[0045] Similarly, if the power supply of the second power supply is abnormal, the bus battery group voltage of the second DC bus will be abnormal. Therefore, it is necessary to connect the first DC bus and the second DC bus in parallel through a contactor so that the first power supply can replace the second power supply to power the second DC bus, and the first power supply also powers the first DC bus.

[0046] Of course, in addition to the contactor, a first switch (connection switch) may be provided between the first section of the DC bus and the second section of the DC bus. The first switch may be, for example, an air switch.

[0047] When the operator inspects the DC bus, the air switch must be disconnected. After the inspection is completed, the air switch is closed, the main control module is powered on and reset, and the contactor returns to the disconnected state, such as the normally open state. The two sections of the DC bus are independent of each other again and are powered by different power supplies.

[0048] In a specific embodiment, when the main control module switches the power supply, it can also control the DC bus with abnormal bus battery pack voltage to be disconnected from the power supply to which it is originally connected.

[0049] For example, each DC bus is connected to its original power supply via a circuit breaker.

[0050] Under normal circumstances, the circuit breaker is in the closed position and the DC bus is powered by its original power supply. If the original power supply cannot supply power normally, the bus battery pack voltage of the DC bus will be abnormal. At this time, the main control module will disconnect the circuit breaker and put it in the open position, so that the original power supply will no longer continue to power the DC bus.

[0051] The main control module controls the contactor to close and connect another power supply to the abnormal DC bus, thereby realizing the switching of the power supply.

[0052] A contactor can be a circuit breaker, a relay, or other element that can be used as a switch.

[0053] For example:

[0054] Under normal circumstances, circuit breaker A and interconnecting switch A are both in the closed position, circuit breaker C is in the open position, and DC power supply system A is powered by DC power supply A. When DC power supply A fails, the main control module detects that the busbar battery group voltage of DC power supply system A is abnormal, disconnects circuit breaker A, closes circuit breaker C, and interconnecting switch A does not operate (in the closed position). The power supply of DC power supply system A is switched from DC power supply A to DC power supply B, completing the automatic switching of charging DC power supply.

[0055] Among them, the B-way DC power supply is the original power supply of the B-way DC power supply system. Under normal circumstances, the B circuit breaker and the B contact switch are both in the closed position, the C circuit breaker is in the open position, and the B-way DC power supply system is powered by the B-way DC power supply.

[0056] This embodiment can accurately and quickly identify faults: the automatic switching device of the DC power supply in the dual-configuration DC system can quickly and accurately identify power supply faults so as to switch the power supply in time to ensure stable operation of the system.

[0057] This embodiment can automatically switch the control: in the case of no one on duty, the automatic switching device of the DC power supply has an automatic control function, which can automatically switch the power supply according to the status of the system, avoiding problems caused by untimely manual operation.

[0058] This embodiment can be intelligent and automated: the automatic switching device of the DC power supply is highly intelligent and automated to reduce the need for manual intervention and improve work efficiency and system reliability.

[0059] This embodiment determines whether the power supply of the DC bus is normal by monitoring the target voltage of the two sections of the DC bus in the dual configuration DC system substation. When it is determined that the power supply of one section of the DC bus is abnormal, the normal power supply is used to replace the abnormal power supply, so as to automatically switch the power supply of the abnormal DC bus, so as to quickly restore the power supply to the DC bus with abnormal voltage and restore the normal operation of the power grid. This embodiment will change the current situation of passive and lagging operation of personnel through the automatic switching of the DC power supply, realize uninterrupted power supply, reduce power outage time, avoid losses caused by power outages, and improve the efficiency of operation and maintenance. This embodiment can realize the automatic switching of dual power supplies during failure, maintenance and operation mode adjustment, reduce the operation of equipment by operation and maintenance personnel, and improve the safety factor of operation. This embodiment improves power supply reliability, reduces complaints caused by frequent power outages, improves user experience, and has broad application prospects.

[0060] In one embodiment, the target voltage also includes a bus unbalanced voltage of each of the two DC bus sections, wherein the bus unbalanced voltage is the difference between the high-end voltage and the low-end voltage of the same DC bus section, the high-end voltage is the voltage difference between the positive potential and the zero potential of the same DC bus section, and the low-end voltage is the voltage difference between the zero potential and the negative potential of the same DC bus section;

[0061] The method further includes:

[0062] If the DC bus unbalanced voltage of the target DC bus is greater than the corresponding DC bus unbalanced voltage threshold, it is determined that the target DC bus is not high-resistance grounded, and the contactor is locked and controlled by the contactor control module to be in an open and prohibited from being attracted state to prohibit the parallel connection of the first DC bus and the second DC bus, wherein the target DC bus includes at least one of the first DC bus and the second DC bus.

[0063] Specifically, the first potential difference includes the difference between any two potentials among the positive potential, the negative potential and the zero potential of the first section of the DC bus;

[0064] The second potential difference includes the difference between any two potentials among the positive potential, the negative potential and the zero potential of the second section of the DC bus;

[0065] The bus unbalanced voltage of the first section of the DC bus is the difference between the high-end voltage and the low-end voltage of the first section of the DC bus;

[0066] The bus unbalanced voltage of the second section of the DC bus is the difference between the high-end voltage and the low-end voltage of the second section of the DC bus;

[0067] Among them, the high-end voltage is the potential difference between the positive potential and the zero potential of the same section of the DC bus;

[0068] The low-end voltage is the potential difference between the zero potential and the negative potential of the same section of the DC bus.

[0069] High-end voltage and low-end voltage are both potential differences or voltage differences.

[0070] For example, the voltage difference between the positive potential and the 0 potential of the first section of the DC bus is called the high-end voltage of the I-section bus;

[0071] The voltage difference between the 0 potential and the negative potential of the first section of the DC bus is called the low-end voltage of the I section bus.

[0072] The voltage difference between the positive potential and the 0 potential of the second section DC bus is called the high-end voltage of the II section bus;

[0073] The voltage difference between the 0 potential and the negative potential of the second section of the DC bus is called the low-end voltage of the section II bus.

[0074] The difference between the high-end voltage of bus section I and the low-end voltage of bus section I is called the unbalanced voltage of bus section I;

[0075] The difference between the high-end voltage of section II bus and the low-end voltage of section II bus is called the unbalanced voltage of section II bus.

[0076] If the unbalanced voltage of the first section of the DC bus is greater than the unbalanced voltage threshold of the first section of the DC bus, it is determined that the first section of the DC bus is not high-resistance grounded, and the contactor is controlled to be in an open and prohibited from being attracted state to prohibit the first section of the DC bus and the second section of the DC bus from being connected in parallel, that is, prohibiting the two sections of the DC bus from being connected in parallel.

[0077] If the unbalanced voltage of the second section of the DC bus is greater than the unbalanced voltage threshold of the second section of the DC bus, it is determined that the second section of the DC bus is not high-resistance grounded, and the contactor is controlled to be in an open and prohibited from being attracted state to prohibit the second section of the DC bus and the second section of the DC bus from being connected in parallel, that is, prohibiting the two sections of the DC bus from being connected in parallel.

[0078] The first section of the DC bus and the second section of the DC bus may be non-high-resistance grounded at the same time, that is, a ground fault may occur, or a ground fault may occur in one of the sections.

[0079] The control contactor is in the disconnected state and is prohibited from closing, that is, the contactor is locked.

[0080] This embodiment calculates the bus unbalanced voltage of each of the two DC bus sections, and then compares the bus unbalanced voltage with the respective unbalanced voltage thresholds, so as to determine whether a ground fault occurs in each DC bus section. When a ground fault occurs in at least one DC bus section, the contactor is controlled to be in an open state and prohibited from being attracted, thereby prohibiting the parallel connection of the two DC bus sections. This can effectively prevent the DC bus section with a ground fault from interfering with the normally operating DC bus section, effectively avoid safety problems caused by misoperation of the contactor due to non-compliance with the conditions, and ensure the safety of part of the power grid.

[0081] In one embodiment, the target voltage further includes a two-section bus voltage difference, wherein the two-section bus voltage difference is a difference between a bus battery pack voltage of a first section of the DC bus and a bus battery pack voltage of a second section of the DC bus;

[0082] The method further includes:

[0083] If the voltage difference between the two bus sections is greater than the parallel voltage difference threshold, the contactor is controlled by the contactor control module to be in an open state and prohibited from being attracted, so as to prohibit the parallel connection of the second DC bus section and the second DC bus section.

[0084] Specifically, the difference between the voltage of the bus battery group of section I and the voltage of the bus battery group of section II is called the voltage difference between the two bus sections.

[0085] If the voltage difference between the two bus sections is greater than the parallel voltage difference threshold, then if the two DC bus sections are connected in parallel, an impact current will be generated. Therefore, the contactor needs to be locked (the control contactor is in the disconnected and prohibited from being attracted state) to prohibit the parallel connection of the two DC bus sections.

[0086] This embodiment calculates the voltage difference between the two sections of the DC bus, and then compares the voltage difference between the two sections of the bus with the voltage difference threshold for parallel connection. When necessary, the contactor can be controlled to be in a disconnected and non-closing state to prohibit the parallel connection of the two sections of the DC bus. This can effectively avoid the impact current generated by the parallel connection of the two sections of the DC bus, thereby avoiding threats to the life safety of operators and avoiding damage to power supply sources such as batteries, effectively ensuring the personal safety of personnel and the safety of power grid operation.

[0087] In one embodiment, the method further comprises:

[0088] If the bus battery group voltage of the target DC bus drops intermittently, the contactor is controlled by the contactor control module to be in an open state and prohibited from being attracted, so as to prohibit the parallel connection of the second section DC bus and the second section DC bus;

[0089] In step S200, if the bus battery group voltage of any section of the DC bus is detected to be abnormal based on the target voltage at different sampling times, the contactor control module controls the contactor to be attracted to connect the first section of the DC bus and the second section of the DC bus in parallel, including:

[0090] If, based on the target voltage at different sampling times, it is monitored that the bus battery pack voltage of any section of the DC bus continues to decrease, and the conditions for controlling the contactor to be in the disconnected and prohibited energization state are not met, the contactor control module controls the contactor to be energized to parallel the first section of the DC bus and the second section of the DC bus.

[0091] Specifically, if the intermittent drop in the battery pack voltage of a certain DC bus is detected, it means that the power supply of the DC bus may be unstable. At this time, it is impossible to determine whether the power supply is really unable to supply power normally. In order to prevent blind switching of power supply when the power supply is unstable, this embodiment will lock the contactor when the battery pack voltage drops intermittently (discontinuously), that is, control the contactor to be in a disconnected and prohibited suction state, thereby prohibiting the parallel connection of two sections of DC buses. In addition, the main control module can also control the device to issue an abnormal alarm for the DC bus battery pack.

[0092] This embodiment allows two sections of DC bus to be connected in parallel only when it is detected that the bus battery group voltage of any section of the DC bus continues to decrease and the condition that the control contactor is in the disconnected and prohibited pull-in state is not met.

[0093] Among them, the condition of controlling the contactor to be in the disconnected and prohibited pull-in state not being met means that there is no need to control the contactor to be in the disconnected and prohibited pull-in state, or the contactor is not currently in the disconnected and prohibited pull-in state, specifically, the following conditions are not met or the following situations are excluded:

[0094] The DC bus unbalance voltage of the target DC bus is greater than the corresponding DC bus unbalance voltage threshold, and the target DC bus is not high-resistance grounded.

[0095] The pressure difference between the two bus sections is greater than the parallel pressure difference threshold.

[0096] The bus battery voltage of the target DC bus drops intermittently.

[0097] or,

[0098] The condition that the control contactor is in the disconnected and prohibited pickup state is not met means that the following conditions are met:

[0099] The DC bus unbalance voltage of the target DC bus is not greater than the corresponding DC bus unbalance voltage threshold, or there is no non-high-resistance grounding of the DC bus;

[0100] and,

[0101] The pressure difference between the two bus sections is not greater than the parallel pressure difference threshold;

[0102] and,

[0103] There is no intermittent voltage drop of the DC bus battery pack.

[0104] Excluding the above situations, if it is detected that the voltage of a DC bus battery pack continues to decrease, the contactor will be pulled in and the two DC buses will be connected in parallel. In addition, the main control module can also control the device to issue an abnormal alarm for the DC bus battery pack.

[0105] The continuous reduction may, for example, mean that the bus battery group voltage decreases in sequence at a plurality of consecutive sampling moments (for example, 3 consecutive sampling moments, 4 consecutive sampling moments, or 6 consecutive sampling moments, etc.).

[0106] In addition, it should be noted that when the control contactor is in the disconnected and prohibited closing state, manual closing of the contactor can be prohibited, that is, manual control of the contactor closing is prohibited. This can prevent operators from mistakenly operating the contactor without knowing that a ground fault has occurred in the DC bus or that two parallel DC buses may generate a surge current, thereby avoiding potential safety hazards to the power grid safety, the personal safety of operators, and the safety of the power supply.

[0107] In this embodiment, when it is detected that the voltage of a DC bus battery pack continues to decrease and there is no need to control the contactor to be in a disconnected state and prohibited from being attracted, two DC buses are connected in parallel. This can quickly switch the available power supply for the DC bus, and can also prevent the operator from mistakenly operating the contactor without knowing that a ground fault has occurred in the DC bus or that a surge current may be generated by connecting two DC buses in parallel, thereby avoiding safety hazards to the safety of the power grid, the personal safety of the operators, and the safety of the power supply.

[0108] In one embodiment, the automatic switching device of the DC power supply further includes an alarm module, and the method further includes:

[0109] If the control contactor is in the disconnected and prohibited from attracting state, the control alarm module also issues a corresponding abnormal alarm, wherein the abnormal alarm includes at least one of the first section DC bus grounding alarm, the second section DC bus grounding alarm, and the DC bus battery pack abnormal alarm.

[0110] Specifically, the main control module is connected to the alarm module. When the parallel connection of two sections of DC bus is prohibited, or the control contactor is in a disconnected state and the closure is prohibited, the main control module can also control the alarm module to issue a corresponding alarm. For example, if it is detected that the unbalanced voltage of the first section of the DC bus is greater than the unbalanced voltage threshold of the first section of the DC bus, a grounding alarm of the I section of the DC bus is issued. If it is detected that the unbalanced voltage of the second section of the DC bus is greater than the unbalanced voltage threshold of the second section of the DC bus, a grounding alarm of the II section of the DC bus is issued. If it is detected that the voltage difference between the two sections of the bus is greater than the parallel voltage difference threshold, the alarm module issues a first abnormal alarm for the DC bus battery pack. If it is detected that the voltage of a DC bus battery pack intermittently drops, the alarm module issues a second abnormal alarm for the DC bus battery pack.

[0111] In order to distinguish different types of alarms, the above-mentioned different abnormal alarms can be presented in different alarm forms, for example, different abnormal alarms can use different sounds for alarms, or different abnormal alarms can use different alarm texts for alarms, or different abnormal alarms can use different colors of alarm lights for alarms, etc., and this application does not limit this. Among them, when the alarm is issued by the alarm text, the alarm text can be displayed on the display screen of the local device and / or sent to the display screen of the remote end device for display.

[0112] The abnormal voltage of the bus battery pack is caused by the failure of the original power supply of the DC bus to supply power normally, and the failure of the original power supply to supply power normally may be due to a failure of the charger of the power supply. At this time, the original power supply is in a state of only discharging but not charging, so its power gradually decreases. If there is no alarm or processing for a long time, the original power supply will be depleted due to the failure to charge normally for a long time, or even the capacity will be lost.

[0113] Through timely alarms in this embodiment, operators can promptly discover and handle power supply failures of the power supply, thereby avoiding the situation where the power supply, such as the battery pack, cannot be charged normally for a long time and suffers capacity loss or even complete capacity loss due to unattended operation and untimely alarm handling.

[0114] This embodiment can promptly notify operators of abnormal conditions through abnormal alarms to assist operators in timely repairing the abnormalities, thereby avoiding the situation where the power supply is depleted in capacity or even completely lost due to long-term inability to charge normally, thereby ensuring safe and stable operation of the power grid.

[0115] Figure 2 FIG. 1 is a block diagram of an automatic switching device for a DC power supply in an embodiment; Figure 2 , the present application also provides an automatic switching device 00 for a DC power supply, the automatic switching device 00 for a DC power supply comprises a main control module 10, and a voltage detection module 20 and a contactor control module 30 electrically connected to the main control module 10;

[0116] The voltage detection module 20 is connected to the first section of the DC bus and the second section of the DC bus respectively;

[0117] The contactor control module 30 is connected to the contactor and is used to control the contactor to open or close;

[0118] The main control module 10 is used to perform power switching according to any one of the above-mentioned methods for automatically switching a DC power supply.

[0119] Specifically, the automatic switching device 00 of the DC power supply is applied to a DC system substation with a dual configuration.

[0120] The voltage detection module 20 is connected to the first section of the DC bus and the second section of the DC bus respectively, and is used to detect the first potential difference of the first section of the DC bus and the second potential difference of the first section of the DC bus, convert the first potential difference into a first analog amplified signal, convert the second potential difference into a second analog amplified signal, and output the first analog amplified signal and the second analog amplified signal to the main control module 10.

[0121] The main control module 10 is used to respectively obtain the first potential difference of the first section of the DC bus and the second potential difference of the second section of the DC bus at different sampling times by using the voltage detection module 20, and calculate the target voltage at different sampling times according to the first potential difference and the second potential difference, wherein the target voltage includes the bus battery pack voltage of each of the two sections of the DC bus, wherein the bus battery pack voltage is the potential difference between the positive potential and the negative potential of the same section of the DC bus;

[0122] The main control module 10 is also used to control the contactor control module 30 to close and connect the first section of the DC bus and the second section of the DC bus in parallel if the bus battery pack voltage of any section of the DC bus is abnormal based on the target voltage at different sampling times, so as to use the normal power supply to power the DC bus with abnormal bus battery pack voltage, wherein the normal power supply is the power supply corresponding to the DC bus with normal bus battery pack voltage.

[0123] The main control module 10 is specifically used to convert the first analog amplified signal into a corresponding first potential difference, and convert the second analog amplified signal into a corresponding second potential difference.

[0124] This embodiment determines whether the power supply of the DC bus is normal by monitoring the target voltage of the two sections of the DC bus in the dual configuration DC system substation. When it is determined that the power supply of one section of the DC bus is abnormal, the normal power supply is used to replace the abnormal power supply, so as to automatically switch the power supply of the abnormal DC bus, so as to quickly restore the power supply to the DC bus with abnormal voltage and restore the normal operation of the power grid. This embodiment will change the current situation of passive and lagging operation of personnel through the automatic switching of the DC power supply, realize uninterrupted power supply, reduce power outage time, avoid losses caused by power outages, and improve the efficiency of operation and maintenance. This embodiment can realize the automatic switching of dual power supplies during failure, maintenance and operation mode adjustment, reduce the operation of equipment by operation and maintenance personnel, and improve the safety factor of operation. This embodiment improves power supply reliability, reduces complaints caused by frequent power outages, improves user experience, and has broad application prospects.

[0125] In one embodiment, the target voltage also includes the bus unbalanced voltage of each of the two sections of DC bus; wherein the bus unbalanced voltage is the difference between the high-end voltage and the low-end voltage of the same section of DC bus, the high-end voltage is the voltage difference between the positive potential and the zero potential of the same section of DC bus, and the low-end voltage is the voltage difference between the zero potential and the negative potential of the same section of DC bus;

[0126] The main control module 10 is also used to determine that the target DC bus is not high-resistance grounded if the DC bus unbalanced voltage of the target DC bus is greater than the corresponding DC bus unbalanced voltage threshold, and control the contactor to be in an open and prohibited attraction state through the contactor control module 30 to prohibit the parallel connection of the first DC bus and the second DC bus, wherein the target DC bus includes at least one of the first DC bus and the second DC bus.

[0127] In one embodiment, the target voltage further includes a two-section bus voltage difference, wherein the two-section bus voltage difference is a difference between a bus battery pack voltage of a first section of the DC bus and a bus battery pack voltage of a second section of the DC bus;

[0128] The main control module 10 is also used to control the contactor to be in an open and prohibited pull-in state through the contactor control module 30 if the voltage difference between the two bus sections is greater than the parallelable voltage difference threshold, so as to prohibit the parallel connection of the second DC bus section and the second DC bus section.

[0129] In one embodiment, the main control module 10 is further used to control the contactor to be in an open and prohibited pull-in state through the contactor control module 30 if the bus battery group voltage of the target DC bus intermittently drops, so as to prohibit the parallel connection of the second DC bus segment and the second DC bus segment;

[0130] The main control module 10 is specifically used to control the contactor to be attracted to parallel the first section of the DC bus and the second section of the DC bus if it is monitored that the bus battery group voltage of any section of the DC bus continues to decrease based on the target voltage at different sampling times, and the condition that the control contactor is in an open state and the attraction state is prohibited is not met.

[0131] In one embodiment, the automatic switching device 00 of the DC power supply further includes an alarm module;

[0132] The main control module 10 is also used to control the alarm module to issue a corresponding abnormal alarm if the control contactor is in a disconnected and prohibited from being attracted state, wherein the abnormal alarm includes at least one of the first section DC bus grounding alarm, the second section DC bus grounding alarm, and the DC bus battery pack abnormal alarm.

[0133] The functions of the main control module 10 are specifically described above and will not be repeated here.

[0134] In one embodiment, the contactor control module 30 includes a relay module 31 and a relay control module 32 that are electrically connected;

[0135] The relay module 31 is connected to the contactor;

[0136] The relay control module 32 is connected to the main control module 10, and is used to control the relay in the relay module 31 to be attracted so that the contactor is energized and attracted if it receives the attraction signal of the main control module 10;

[0137] The relay control module 32 is further used to control the relay in the relay module 31 to disconnect so that the contactor is powered off and disconnected if a disconnection signal is received from the main control module 10;

[0138] The relay control module 32 is also used to, if it continues to receive the disconnection signal from the main control module 10, continuously control the relay in the relay module 31 to disconnect so that the contactor is powered off and in a disconnected and non-closing state.

[0139] Specifically, the contactor control module 30 of this embodiment controls the contactor to be powered on or off by controlling the relay to be pulled on or off. The contactor will be pulled on when powered on and will be disconnected when powered off, thereby controlling whether the first DC bus and the second DC bus are parallel.

[0140] In addition, in this embodiment, the pull-in signal and the disconnection signal are autonomously generated by the main control module 10 according to logic judgment.

[0141] If the main control module 10 detects that the bus battery pack voltage of any section of the DC bus is abnormal based on the target voltage at different sampling times, a pull-in signal is generated.

[0142] If the main control module 10 detects that the DC bus unbalanced voltage of the target DC bus is greater than the corresponding DC bus unbalanced voltage threshold, it determines that the target DC bus is not high-resistance grounded and generates a disconnection signal.

[0143] If the main control module 10 detects that the pressure difference between the two bus sections is greater than the parallel pressure difference threshold, a disconnection signal is generated.

[0144] If the main control module 10 detects that the bus battery group voltage of the target DC bus intermittently drops, a disconnection signal is generated.

[0145] If the main control module 10 detects that the bus battery voltage of any section of the DC bus continues to decrease based on the target voltage at different sampling times, and does not meet the conditions of controlling the contactor to be in the disconnected and prohibited closing state, a closing signal is generated.

[0146] This embodiment controls the contactor to be powered on or off by controlling the relay to be closed or disconnected. The contactor will be closed when powered on and disconnected when powered off, thereby quickly controlling whether the first section of the DC bus and the second section of the DC bus are in parallel.

[0147] In one embodiment, the relay control module 32 includes a first resistor, an optical coupler, a second resistor, a third resistor, a first switch tube and a first diode;

[0148] The relay module 31 includes a first relay and a first connection terminal;

[0149] The first end of the first resistor is connected to the main control module 10, and the second end is connected to the second end of the optocoupler. The first end of the optocoupler is connected to the first voltage, the third end is grounded, the fourth end is connected to the second voltage through the second resistor, and the fourth end is also connected to the first end of the first switch tube through the third resistor. The second end of the first switch tube is connected to the second voltage, the third end is connected to the cathode of the first diode, and the third end is also connected to the first contact of the first relay. The anode of the first diode is grounded;

[0150] The fourth contact of the first relay is grounded, an iron core is connected between the first contact and the fourth contact of the first relay, the fifth contact of the first relay is connected to the third voltage, and the second contact is connected to the contactor through the first terminal, the fifth contact of the first relay is connected to the second contact when power is on, and the fifth contact of the first relay is connected to the third contact when power is not on.

[0151] Specifically, Figure 3 FIG. 1 is a circuit diagram of a contactor control module 30 in one embodiment; Figure 3 , the relay control module 32 includes a first resistor R27, an optical coupler U5, a second resistor R28, a third resistor R26, a first switch tube Q2 and a first diode D2;

[0152] The relay module 31 includes a first relay RLY2 and a first connection terminal U37;

[0153] The first end of the first resistor R27 is connected to the main control module 10 to obtain a pull-in signal or a disconnection signal (the signal OUT2 represents the pull-in signal or the disconnection signal through high and low levels), and the second end is connected to the second end of the optical coupler U5. The first end of the optical coupler U5 is connected to a first voltage (for example, 3.3V), the third end is grounded GND, the fourth end is connected to a second voltage (for example, +5V) through the second resistor R28, and the fourth end is also connected to the first end of the first switch tube Q2 through the third resistor R26. The second end of the first switch tube Q2 is connected to the second voltage (for example, +5V), the third end is connected to the cathode of the first diode D2, and the third end is also connected to the first contact of the first relay RLY2. The anode of the first diode D2 is grounded GND;

[0154] The fourth contact of the first relay RLY2 is grounded GND, an iron core is connected between the first contact and the fourth contact of the first relay RLY2, the fifth contact of the first relay RLY2 is connected to the third voltage (for example, 24V), and the second contact is connected to the contactor through the first terminal U37, and when the first relay RLY2 is energized, the fifth contact of the first relay RLY2 is connected to the second contact, and when the first relay RLY2 is not energized, the fifth contact of the first relay RLY2 is connected to the third contact.

[0155] The first terminal U37 has a first end connected to the second contact of the first relay RLY2 and a second end connected to the ground. The first terminal U37 has a first end and a second end connected to the contactor.

[0156] The first switch tube Q2 may be a triode or a MOS tube. If the first switch tube Q2 is a triode, the first end of the first switch tube Q2 is the base, the second end is the emitter, and the third end is the collector.

[0157] The signal OUT2 is a control signal output by the main control module 10 . When the signal OUT2 is at a high level, it is a disconnection signal. When the signal OUT2 is at a low level, it is a pull-in signal.

[0158] More specifically, taking the first switch tube Q2 as a transistor as an example, when the signal OUT2 output of the main control module 10 is at a low level, the optical coupler U5 is turned on, pulling down the base of the NPN transistor Q2, the emitter collector of the transistor is turned on, and the first relay RLY2 is energized. At this time, the coil of the contactor is energized and the contactor is energized.

[0159] When the signal OUT2 of the main control module 10 outputs a high level, the optocoupler U5 is not conducting, the base of the transistor Q2 is pulled high, the transistor Q2 is turned off, and the first relay RLY2 is disconnected. At this time, the coil of the contactor is not energized and the contactor is disconnected. When the contactor is locked, the signal OUT2 is prohibited from outputting a low level, and the contactor remains normally open.

[0160] When the contactor coil is energized, the coil current will generate a magnetic field. The generated magnetic field causes the static iron core to generate electromagnetic attraction, attracting the moving iron core and driving the contactor point to move. The normally closed contact is disconnected and the normally open contact is closed, and the two are linked. When the coil is de-energized, the electromagnetic attraction disappears, and the armature is released under the action of the release spring, restoring the contact. The normally open contact is disconnected and the normally closed contact is closed. In this design, a relay is used to control the power on and off of the contactor coil.

[0161] In one embodiment, the contactor control module 30 further includes an indication module connected to the relay control module 32.

[0162] The indicating module includes a fourth resistor R24 ​​and a light emitting diode LED3;

[0163] The third end of the first switch tube Q2 is also connected to the ground GND through the fourth resistor R24 ​​and the light emitting diode LED3.

[0164] Specifically, when the signal OUT2 output of the main control module 10 is at a low level, the optocoupler U5 is turned on, pulling down the base of the NPN transistor Q2, the emitter collector of the transistor is turned on, and the light-emitting diode LED3 emits light, indicating that the two DC busbars are in parallel.

[0165] If the signal OUT2 output is a high level, the light emitting diode LED3 cannot emit light, indicating that the two sections of the DC bus are not connected in parallel.

[0166] In this embodiment, the indication module can clearly indicate to the user whether two sections of DC bus are connected in parallel.

[0167] In one embodiment, the automatic switching device 00 of the DC power supply further includes a contactor manual control module connected to the main control module 10;

[0168] The contactor manual control module is used to receive the manual operation of the user, generate a pull-in instruction or a disconnection instruction according to the manual operation, and output the pull-in instruction or the disconnection instruction to the main control module 10;

[0169] The main control module 10 is used to generate a pull-in signal according to the pull-in instruction and output the pull-in signal to the relay control module 32;

[0170] The main control module 10 is further used to generate a disconnection signal according to the disconnection instruction, and output the disconnection signal to the relay control module 32 .

[0171] Specifically, the automatic switching device 00 of the DC power supply of this embodiment is also provided with a contactor manual control module, through which the operator can manually connect two sections of DC bus bars in parallel or manually disconnect two sections of DC bus bars in parallel, thus achieving more convenient and flexible human-computer interactive control.

[0172] Figure 4 is a circuit diagram of a contactor manual control module in one embodiment, refer to Figure 4 , a first key circuit and a second key circuit of the contactor manual control module;

[0173] The first end of the resistor R156 of the first key circuit is connected to the first voltage (for example, 3.3V), the second end is connected to the ground GND through the capacitor C76, and the second end of the resistor R156 is connected to the main control module 10 through the wiring terminal U97. The first end of the wiring terminal U97 is grounded, and the second end is connected to the second end of the resistor R156 and the main control module 10.

[0174] The first end of the resistor R155 of the second key circuit is connected to the first voltage (for example, 3.3V), the second end is connected to the ground GND through the capacitor C75, and the second end of the resistor R155 is connected to the main control module 10 through the wiring terminal U98. The first end of the wiring terminal U98 is grounded, and the second end is connected to the second end of the resistor R155 and the main control module 10.

[0175] The first key circuit and the second key circuit are also each provided with a key, namely key 1 and key 2, which respectively control the on and off of the contactor. The main control module 10 uses an external interrupt to detect whether the key is pressed. When key 1 of the first key circuit is pressed, OUT2 of the main control module 10 outputs a low level, so that the contactor is attracted. When key 2 of the second key circuit is pressed, OUT2 of the main control module 10 outputs a high level, so that the contactor is disconnected.

[0176] This embodiment provides a contactor manual control module to facilitate operators to manually control the on and off of the contactor according to actual needs.

[0177] In one embodiment, the voltage detection module 20 includes at least one voltage detection unit, each of which includes an isolated operational amplifier unit and a voltage divider unit that are electrically connected;

[0178] The two ends of the voltage divider unit are respectively connected to two different detection points of the same section of the DC bus, wherein the two different detection points correspond to two different target potentials on the DC bus, and are used to divide the potential difference obtained from the two target potentials through a series resistor, and input the obtained divided voltage to the isolation operational amplifier unit;

[0179] The isolation operational amplifier unit is used to isolate and amplify the divided voltage and input the obtained analog amplified signal to the main control module 10;

[0180] The main control module 10 is used to convert the analog amplified signal into a potential difference between two target potentials according to the amplification factor and the voltage division ratio, wherein the two target potentials are any two of a positive potential, a negative potential and a zero potential.

[0181] Specifically, Figure 5 is a circuit diagram of a voltage detection unit in one embodiment; Figure 5 The two ends of the voltage detection unit are respectively connected to two different detection points of the same DC bus. The two different detection points can be detection points corresponding to any two potentials among positive potential, negative potential and zero potential. Figure 5The detection points corresponding to the positive potential and negative potential of the same DC bus are taken as an example. The voltage difference between the two ends of the voltage detection unit is divided by the voltage divider unit, and the obtained voltage is input to the second pin and the third pin (differential voltage input end) of the isolation operational amplifier U2. The voltage divider unit includes resistors R1, R2, R3, R5, R7, R8, and R9. The two ends of the resistor R5 are respectively connected to the second pin and the third pin of the isolation operational amplifier U2. The first pin of the isolation operational amplifier U2 is connected to the voltage GL1_3.3V, and the fourth pin is grounded GL1_GND. The first pin of the isolation operational amplifier U2 is also grounded GL1_GND through the capacitor C1. The eighth pin of the isolation operational amplifier U2 is connected to a voltage of 3.3V, and the eighth pin of the isolation operational amplifier U2 is also grounded to GND through a capacitor C2. The sixth pin of the isolation operational amplifier U2 is grounded to GND, and the seventh pin of the isolation operational amplifier U2 is grounded to GND through a resistor R6 and a capacitor C3. The common node of the resistor R6 and the capacitor C3 is connected to the main control module 10, and is used to output an analog amplified signal ACD1 to the main control module 10.

[0182] The model of the isolation operational amplifier U2 may be AMC1200BDWVR.

[0183] The two ends of the voltage detection unit can be connected to two potentials through the connection terminals.

[0184] The voltage detection unit can access the voltage GL1_3.3V through the fourth pin of the isolated power supply U99. The voltage detection unit can be grounded GL1_GND through the third pin of the isolated power supply U99. The fourth pin of the isolated power supply U99 is also grounded GL1_GND through capacitor C54.

[0185] The second pin of the isolated power supply U99 is connected to the voltage +5V, and the second pin of the isolated power supply U99 is also connected to the ground GND through the capacitor C53, and the first pin of the isolated power supply U99 is connected to the ground GND. The isolated power supply U99 converts the +5V voltage into the voltage GL1_3.3V.

[0186] The model of the isolated power supply U99 may be B0503S-1W.

[0187] AMC1200 is an isolated operational amplifier. The detected voltage is divided by a series of resistors and then input to the differential voltage input terminal of the isolated operational amplifier. After being isolated inside the device, it is amplified and output to the ADC interface of the main control chip. Then the main control chip calculates the measured voltage value according to the amplification factor and the voltage division ratio. The main purpose of using an isolated operational amplifier is to isolate the high-voltage area from the low-voltage area to prevent the high voltage from damaging the low-voltage circuit. Therefore, the isolated operational amplifier also requires a DCDC isolated power supply module to provide power. B0503S is an isolated power supply that converts DC5V to DC3.3V, and its input and output are isolated from each other.

[0188] Figure 5 is a circuit diagram of a voltage detection unit in the voltage detection module 20, and the circuit diagrams of other voltage detection units are similar to Figure 5 resemblance.

[0189] For example, the first section of the DC bus has three potential difference detections:

[0190] (1) The voltage difference (potential difference) between the positive potential and the negative potential is called the bus battery voltage of section I;

[0191] (2) The voltage difference (potential difference) between the positive potential and the 0 potential is called the high-end voltage of bus section I;

[0192] (3) The voltage difference (potential difference) between 0 potential and negative potential is called the low-end voltage of bus section I.

[0193] The second section of the DC bus has three potential difference detections:

[0194] (4) The voltage difference (potential difference) between the positive potential and the negative potential is called the busbar battery group voltage of section II;

[0195] (5) The voltage difference (potential difference) between the positive potential and the 0 potential is called the high-end voltage of the busbar in section II;

[0196] (6) The voltage difference (potential difference) between the 0 potential and the negative potential is called the low-end voltage of bus section II.

[0197] Therefore, the voltage detection module 20 has at least 6 voltage detection units. Different voltage detection units are responsible for detecting different potential differences. The 6 voltage detection units output analog amplified signals ACD1, ACD2, ACD3, ACD4, ACD5 and ADC6 to the main control module 10 respectively.

[0198] Figure 6 For a circuit diagram of the main control module 10 in one embodiment of the present application, refer to Figure 6 , U1 is the main control chip, model STM32F103c8t6. Its 20th and 44th pins are for power-on boot, and are connected to the negative power supply through resistors R4 and R11. Pins 5 and 6 are external clock input pins, which need to be connected to both ends of the crystal oscillator X1, and connected to the negative power supply through capacitors C8 and C9. H1 is the program burning interface, connected to the debug pins SWCLK and SWDIO of the main control. The main control has 3 power pins, which need to be connected to the positive power supply, and capacitors C10, C11, and C13 are connected in parallel to act as a filter. ADC1 and ADC2 interfaces are used to detect voltage, and CN1 is the LCD screen interface. SW1 is the reset circuit. When the button SW1 is pressed, RST is low and the MCU restarts. See the circuit schematic diagram Figure 6 .

[0199] Pins 5 and 6 of the main control chip U1 are connected to the two ends of the crystal oscillator X1 to obtain signals OS_8M_IN and OS_8M_OUT. One end of the crystal oscillator X1 is grounded through capacitor C8, and the other end is grounded through capacitor C9. Pin 7 of the main control chip U1 is connected to the reset signal RST. The first end of the resistor R23 in the reset module is connected to the voltage 3.3V, and the second end is grounded GND through capacitor C7. The two ends of capacitor C7 are connected to the two ends of switch SW1, and the second end of resistor R23 is also connected to pin 7 of the main control chip U1. Pin 8 of the main control chip U1 is grounded GND, pin 9 of the main control chip U1 is connected to the voltage 3.3V, and pins 10, 11, 16-19 of the main control chip U1 are respectively connected to 6 different voltage detection units to obtain analog amplified signals ACD1, ACD2, ACD3, ACD4, ACD5 and ADC6 respectively.

[0200] Pins 12 and 13 of the main control chip U1 are connected to the serial port 2 (USART2_RX, USART2_TX) of the wireless communication module. Pins 14 and 15 of the main control chip U1 are connected to the two setting terminals M0 and M1 of the wireless communication module for configuring the working mode of the wireless module.

[0201] Pin 20 of the main control chip U1 is connected to the ground GND through a resistor R11, pins 21 and 22 of the main control chip U1 are extension pins, pins 23, 47, and 35 of the main control chip U1 are grounded, pins 24, 48, and 36 of the main control chip U1 are connected to a voltage of 3.3V, pin 44 of the main control chip U1 is connected to the ground through a resistor R4, and pin 42 of the main control chip U1 is the output end of the pull-in signal or the disconnection signal, that is, the output end of the signal OUT2. Pin 46 of the main control chip U1 is connected to the cathode of the light-emitting diode LED2, and the anode of the light-emitting diode LED2 is connected to a voltage of 3.3V through a resistor R25. Pins 37 and 34 of the main control chip U1 are connected to pins 3 and 2 of the wiring terminal H1, pin 1 of the wiring terminal H1 is connected to a voltage of 3.3v, pin 3 of the wiring terminal H1 is grounded, and pin 5 of the wiring terminal H1 is connected to the second end of the resistor R23 and pin 7 of the chip U1.

[0202] The ADC module of the main control chip U1 is usually based on the successive approximation register (SAR) architecture, and its working principle is as follows:

[0203] Sampling phase: During the sampling phase, the ADC holds the analog input signal on the sampling capacitor through the sampling switch to stabilize the input voltage. The sampling time determines the sampling duration of the input signal, affecting the accuracy and speed of the conversion. A longer sampling time helps improve accuracy but reduces the sampling rate.

[0204] Conversion phase: In the conversion phase, the ADC compares the analog voltage with the reference voltage through a successive approximation algorithm to generate a corresponding digital value. In this process, the ADC gradually approximates the voltage value of the analog input signal until it finds a digital code equal to the analog voltage.

[0205] In one embodiment, the automatic switching device 00 for a DC power supply may further include a wireless communication module connected to the main control module 10 .

[0206] The wireless communication module is, for example, a lora wireless module. The wireless communication module includes a chip U13 and a pin header U14. The pin header U14 is used to configure the wireless communication module. M0 and M1 are used to configure the working mode of the wireless module. When both pins are at a low level, serial port data transparent transmission is supported, and wireless modules with the same configuration within the communication range can communicate with each other. A receiving end can be designed to communicate with it. The wireless communication module is connected to the main control module 10 through serial port 2 (USART2_RX, USART2_TX) to realize serial port data transmission and reception.

[0207] In one embodiment, the automatic switching device 00 for DC power supply may further include a power module. Figure 7 This is a circuit diagram of a power module in one embodiment of the present application; Figure 7 , the power module includes a first power unit, a second power unit and a third power unit, Figure 7 The first circuit diagram above shows that the first power supply unit is the first-stage step-down circuit. The input range of this power supply is 85V~275VAC or 100V~370VDC, and the output is DC24V. F25 is a fuse.

[0208] Pins 6 and 5 of U32 are connected to the first ends of capacitors C43, C46, ​​C47 and C44 respectively, pins 3 and 4 of U32 are connected to the second ends of capacitors C43 and C46 respectively, the second end of capacitor C43 is connected to the second ends of capacitors C47 and C44 respectively through inductor L7, pins 6 and 5 of U32 are also connected to the first end of U31, the second ends of capacitors C47 and C44 are also connected to the second end of U31, the third end of U31 is grounded, the fourth end of U31 outputs a voltage of 24V, the fourth end of U31 is also grounded through capacitor C45, and the fourth end of U31 is also grounded through capacitor C48. Pin 2 of U32 is connected to the first end of U30, and pin 2 of U32 is also connected to the PE line (Protective Earth) through capacitor C41. Pin 1 of U32 is connected to the second end of U30, and pin 1 of U32 is also connected to the PE line through capacitor C42. The third end of U30 is connected to the L / DC+ line (Live Line) through resistors R93 and F25. The third end of U30 is also connected to the first ends of capacitor C40, resistor R94, and resistor R95 respectively. The fourth end of U30 is also connected to the second ends of capacitor C40, resistor R94, and resistor R95 and N / DC- line (Neutral Line) respectively.

[0209] U32 can convert AC power into 24V voltage.

[0210] Figure 7 The second circuit diagram in the middle is that the second power supply unit is a second-stage step-down circuit. Pin 1 of U10 is connected to the output end through capacitor C17 and inductor L1 in sequence, and the output end outputs a voltage of +5V. Pin 2 of U10 is connected to a voltage of 24V. Pin 2 of U10 is also connected to ground GND through parallel capacitors C20 and C21. Pin 3 of U10 is connected to a voltage of 24V through resistor R34. Pin 4 of U10 is grounded through resistor R39. Pin 3 of U10 is also grounded through resistor R41. Pin 8 of U10 is connected to the output end through inductor L1. Pin 8 of U10 is also grounded through D6. Pins 7 and 9 of U10 are grounded. Pin 6 of U10 is grounded through capacitor C22. Pin 5 of U10 is grounded through resistor R40. The two ends of capacitor C19 are connected to the output end and ground respectively. The two ends of capacitor C18 are connected to the output end and ground respectively, and the output end is grounded through resistors R31 and R40.

[0211] U10 can convert 24V voltage into +5V voltage to power other modules.

[0212] U32 is an isolated step-down power module. The input range of this power supply is 85V~275VAC or 100V~370VDC, and the output is DC24V. F25 is a fuse. U10 is an LMR14050 device, which is a 40V, 5A step-down regulator with an integrated high-side MOSFET. The device has a wide input voltage range of 4V to 40V. The adjustable switching frequency range of the regulator is wide, and the device also has built-in multiple protection features: cycle-by-cycle current limit protection, thermal sensing and thermal shutdown protection for excessive power consumption, and output overvoltage protection.

[0213] Figure 7 The third circuit diagram above is that the third power supply unit is a third-stage step-down circuit. Pin 1 of U9 is connected to the cathode of D3, the anode of D3 is connected to +5V, pin 1 of U9 is connected to pin 3, pin 2 of U9 is grounded, and pin 5 of U9 is the output terminal with an output voltage of 3.3V. Pin 5 of U9 is grounded through capacitors C15 and C16 connected in parallel.

[0214] This circuit inputs DC24V and outputs DC3.3V in two steps. First, the DC24V is stepped down to DC5V, the output voltage is adjusted by R31 and R40, and then a linear regulator is used to step down the 5V voltage to DC3.3V.

[0215] DC5V=Vout=(1+R31 / R40)*0.75.

[0216] The power module of this embodiment can obtain at least one target voltage through multi-stage voltage reduction to supply power to other modules of the device.

[0217] Figure 8 This is a structural block diagram of an automatic switching device 00 for a DC power supply in another embodiment of the present application. Figure 8 The automatic switching device 00 of the DC power supply includes a main control module 10, and a power module, a voltage detection module 20, a contactor control module 30, a key module, a wireless module and a liquid crystal screen connected to the main control module 10.

[0218] The power module can convert AC85-275 input and DC110-DC385 input into DC24V, and can further convert DC24V input voltage into DC3.3C output voltage.

[0219] Figure 8 The DC bus section I and the DC bus section II can be connected through an air switch and a contactor, wherein the air switch is closed by default and the contactor is disconnected by default. Both the DC bus section I and the DC bus section II contain a positive potential of +110V, a negative potential of -110V and a zero potential of 0V.

[0220] The LCD screen can display data such as target voltage, potential difference, etc. in real time, and can also display whether two DC bus sections are currently in parallel, etc., for users to easily view.

[0221] It should be noted that the resistance values, capacitance values, voltages, chip models, terminal models, inductance values, etc. in the various circuit diagrams of this application are merely illustrative examples. The actual values ​​are determined according to the actual application scenarios, and this application does not impose any restrictions on this.

[0222] The present application can accurately and quickly identify faults: the automatic switching device 00 of the DC power supply in the dual-configuration DC system needs to be able to quickly and accurately identify power supply failures so as to switch the battery charging power supply in time to ensure stable operation of the system.

[0223] This application can automatically switch control: when there is no one on duty, the device needs to have an automatic control function, which can automatically switch the power supply according to the status of the system to avoid problems caused by untimely manual operation.

[0224] This application can achieve intelligence and automation: the device should be highly intelligent and automated to reduce the need for manual intervention and improve work efficiency and system reliability.

[0225] This application is able to determine the conditions for bus tie switch operation: when operating the bus tie switch, the device should be able to determine whether conditions such as the DC bus voltage difference meet the requirements, to avoid impact current and damage to the battery caused by unmet conditions.

[0226] Automatic switching device: The device can achieve fast and accurate fault identification and automatic switching, reducing the need for human intervention.

[0227] Intelligence and automation: The device adopts the design concept of intelligence and automation, which greatly improves the reliability and work efficiency of the system.

[0228] Condition judgment function: The device has the function of judging the operating conditions of the busbar switch, effectively avoiding safety problems caused by failure to meet the conditions.

[0229] This application has time benefits: the successful application of the automatic switching device 00 of the DC power supply will change the current situation of passive and lagging operation of personnel, realize uninterrupted power supply, reduce power outage time, avoid losses caused by power outages, and improve the efficiency of operation and maintenance.

[0230] This application has safety benefits: by installing the automatic switching device 00 of the DC power supply, the automatic switching of the dual power supply can be realized in the event of failure, maintenance and operation mode adjustment, which reduces the operation of the equipment by the operation and maintenance personnel and improves the safety factor of operation.

[0231] This application has social benefits: the automatic switching device 00 of the DC power supply improves the reliability of power supply, reduces complaints and work orders caused by frequent power outages, wins unanimous praise from customers, maintains the company's good social image, and this project has broad application prospects.

[0232] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be completed by instructing the relevant hardware through a computer program, and the program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in the present application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0233] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0234] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for automatically switching a DC power supply, applied to a main control module in an automatic switching device for a DC power supply, wherein the automatic switching device for a DC power supply is applied to a dual-configuration DC system substation, wherein the dual-configuration DC system substation comprises two DC power supplies, wherein the two DC power supplies respectively comprise a first section of a DC bus and a second section of a DC bus powered by different power supplies, wherein the first section of the DC bus and the second section of the DC bus can be connected or disconnected via a contactor, wherein the first section of the DC bus and the second section of the DC bus both comprise a positive potential, a negative potential and a zero potential, wherein the automatic switching device for the DC power supply comprises a main control module, and a voltage detection module and a contactor control module electrically connected to the main control module, wherein the voltage detection module is respectively connected to the first section of the DC bus and the second section of the DC bus, and the contactor control module is connected to the contactor, wherein: The automatic switching method of the DC power supply comprises: The voltage detection module is used to obtain a first potential difference between the first section of the DC bus and a second potential difference between the second section of the DC bus at different sampling times, and a target voltage at different sampling times is obtained according to the first potential difference and the second potential difference, wherein the target voltage includes a bus battery pack voltage of each of the two sections of the DC bus, and the bus battery pack voltage is a potential difference between a positive potential and a negative potential of the same section of the DC bus; If the bus battery pack voltage of any section of the DC bus is monitored to be abnormal based on the target voltage at different sampling times, the contactor control module controls the contactor to be attracted to parallel the first section of the DC bus and the second section of the DC bus, so that the normal power supply can be used to power the DC bus with abnormal bus battery pack voltage, wherein the normal power supply is the power supply corresponding to the DC bus with normal bus battery pack voltage.

2. The automatic switching method of a DC power supply according to claim 1, characterized in that: The target voltage also includes a bus unbalanced voltage of each of the two sections of the DC bus, wherein the bus unbalanced voltage is the difference between the high-end voltage and the low-end voltage of the same section of the DC bus, the high-end voltage is the potential difference between the positive potential and the zero potential of the same section of the DC bus, and the low-end voltage is the potential difference between the zero potential and the negative potential of the same section of the DC bus; The method further comprises: If the DC bus unbalanced voltage of the target DC bus is greater than the corresponding DC bus unbalanced voltage threshold, it is determined that the target DC bus is not high-resistance grounded, and the contactor is controlled by the contactor control module to be in an open and prohibited attraction state to prohibit the parallel connection of the first section of the DC bus and the second section of the DC bus, wherein the target DC bus includes at least one section of the first section of the DC bus and the second section of the DC bus.

3. The automatic switching method of a DC power supply according to claim 1, characterized in that: The target voltage also includes a two-section bus voltage difference, wherein the two-section bus voltage difference is a difference between a bus battery pack voltage of the first section of the DC bus and a bus battery pack voltage of the second section of the DC bus; The method further comprises: If the voltage difference between the two bus sections is greater than the parallel voltage difference threshold, the contactor is controlled by the contactor control module to be in an open and non-closing state to prohibit the parallel connection of the second DC bus section and the second DC bus section.

4. The automatic switching method of a DC power supply according to claim 1, characterized in that: The method further comprises: If the bus battery group voltage of the target DC bus drops intermittently, the contactor is controlled by the contactor control module to be in an open state and prohibited from being attracted, so as to prohibit the parallel connection of the second section DC bus and the second section DC bus; If the bus battery group voltage of any section of the DC bus is detected to be abnormal based on the target voltage at different sampling times, the contactor control module controls the contactor to be attracted to connect the first section of the DC bus and the second section of the DC bus in parallel, including: If, based on the target voltage at different sampling times, it is monitored that the bus battery pack voltage of any section of the DC bus continues to decrease, and the conditions for controlling the contactor to be in a disconnected state and prohibited from being attracted are not met, the contactor is controlled to be attracted through the contactor control module to parallel the first section of the DC bus and the second section of the DC bus.

5. The automatic switching method of a DC power supply according to any one of claims 2 to 4, characterized in that: The automatic switching device of the DC power supply further includes an alarm module, and the method further includes: If the contactor is controlled to be in a disconnected state and the attraction is prohibited, the alarm module is also controlled to issue a corresponding abnormal alarm, wherein the abnormal alarm includes at least one of a first-segment DC bus grounding alarm, a second-segment DC bus grounding alarm, and a DC bus battery pack abnormal alarm.

6. An automatic switching device for a DC power supply, the automatic switching device for the DC power supply is applied to a dual configuration DC system substation, the dual configuration DC system substation includes two DC power supplies, the two DC power supplies each include a first section of a DC bus and a second section of a DC bus powered by different power supplies, the first section of the DC bus and the second section of the DC bus can be connected or disconnected through a contactor, the first section of the DC bus and the second section of the DC bus both include a positive potential, a negative potential and a zero potential, and is characterized in that: The automatic switching device of the DC power supply comprises a main control module, and a voltage detection module and a contactor control module electrically connected to the main control module; The voltage detection module is connected to the first section of the DC bus and the second section of the DC bus respectively; The contactor control module is connected to the contactor; The main control module is used to perform power switching according to the automatic switching method of the DC power supply according to any one of claims 1-5.

7. The automatic switching device of the DC power supply according to claim 6, characterized in that: The contactor control module includes a relay module and a relay control module that are electrically connected; The relay module is connected to the contactor; The relay control module is connected to the main control module, and is used to control the relay in the relay module to be attracted so that the contactor is energized and attracted if a pull-in signal from the main control module is received; The relay control module is further configured to, if receiving a disconnection signal from the main control module, control the relay in the relay module to disconnect so that the contactor is powered off and disconnected; The relay control module is also used for continuously controlling the relay in the relay module to disconnect so that the contactor is powered off and in a disconnected and non-closing state if the disconnection signal from the main control module is continuously received.

8. The automatic switching device for DC power supply according to claim 7, characterized in that: The relay control module includes a first resistor, an optical coupler, a second resistor, a third resistor, a first switch tube and a first diode; The relay module includes a first relay and a first wiring terminal; The first end of the first resistor is connected to the main control module, and the second end is connected to the second end of the optocoupler. The first end of the optocoupler is connected to the first voltage, the third end is grounded, the fourth end is connected to the second voltage through the second resistor, and the fourth end is also connected to the first end of the first switch tube through the third resistor. The second end of the first switch tube is connected to the second voltage, the third end is connected to the cathode of the first diode, and the third end is also connected to the first contact of the first relay. The anode of the first diode is grounded; The fourth contact of the first relay is grounded, an iron core is connected between the first contact and the fourth contact of the first relay, the fifth contact of the first relay is connected to the third voltage, and the second contact is connected to the contactor through the first terminal, the fifth contact of the first relay is connected to the second contact when power is on, and the fifth contact of the first relay is connected to the third contact when power is not on.

9. The automatic switching device of the DC power supply according to claim 7, characterized in that: The automatic switching device of the DC power supply also includes a contactor manual control module connected to the main control module; The contactor manual control module is used to receive a manual operation of a user, generate a pull-in instruction or a disconnection instruction according to the manual operation, and output the pull-in instruction or the disconnection instruction to the main control module; The main control module is used to generate a pull-in signal according to the pull-in instruction, and output the pull-in signal to the relay control module; The main control module is further used to generate a disconnection signal according to the disconnection instruction, and output the disconnection signal to the relay control module.

10. The automatic switching device of the DC power supply according to claim 7, characterized in that: The voltage detection module includes at least one voltage detection unit, each of which includes an isolated operational amplifier unit and a voltage dividing unit that are electrically connected; The two ends of the voltage divider unit are respectively connected to two different detection points of the same section of the DC bus, wherein the two different detection points correspond to two different target potentials on the DC bus, and are used to divide the potential difference obtained from the two target potentials through a series resistor, and input the obtained divided voltage to the isolation operational amplifier unit; The isolation operational amplifier unit is used to isolate and amplify the divided voltage, and input the obtained analog amplified signal to the main control module; The main control module is used to convert the analog amplified signal into a potential difference between two target potentials according to the amplification factor and the voltage division ratio, wherein the two target potentials are any two of a positive potential, a negative potential and a zero potential.

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