Active protection device and method applied to station DC power supply system

Abstract

The invention provides an active protection device and method applied to a station DC power supply system, and relates to the technical field of substation DC power supplies, and the active protection device is connected in series between a DC bus and a DC load branch of the station DC power supply system. Comprising a two-transistor forward DC / DC converter, a single-chip microcomputer control circuit, an output diode and a detection circuit. The input end of the double-transistor forward DC / DC converter is connected with a direct-current power supply, the output end of the double-transistor forward DC / DC converter is connected to a direct-current load branch through an output diode, the single-chip microcomputer control circuit is respectively connected with the double-transistor forward DC / DC converter and the detection circuit, and the detection circuit is connected to the direct-current load branch through the output diode. According to the technical scheme, the grounding fault of the DC bus can be effectively limited and quickly isolated, so that the fault can be prevented from being further expanded to the whole station DC power supply system, and the safety and the stability of the station DC power supply system are improved.

Description

Technical Field

[0001] The present application relates to the technical field of direct current power supply for substations, and in particular to an active protection device and method applied to a direct current power supply system for a substation. Background Art

[0002] In the substation power supply system, the AC circuit and the DC circuit are two independent systems. The AC circuit is generally a grounded system, while the DC circuit is an ungrounded system. Therefore, when AC leaks into DC, it will cause a DC bus grounding fault.

[0003] For DC bus grounding faults caused by AC entering DC, the existing solution is to detect the fault through a portable grounding fault finder, but this method has obvious disadvantages: 1) Due to the low compatibility and poor anti-interference ability of the finder itself, it may cause false alarms of grounding faults; 2) Any feeder branch needs to be tested, which has the disadvantages of large workload and poor timeliness. In addition, a multimeter can be used to remove part of the loop wiring to find the fault, but it is easy to cause accidental touch and contact accidents. More importantly, these instruments or methods cannot effectively limit and quickly isolate the fault, which may cause the fault to further expand to the entire system. Summary of the invention

[0004] The present invention provides an active protection device and method applied to a station DC power supply system, which can effectively limit and quickly isolate a DC bus grounding fault, thereby preventing the fault from further expanding to the entire station DC power supply system, thereby improving the safety and stability of the station DC power supply system.

[0005] In a first aspect, an active protection device applied to a station DC power supply system is provided, wherein the active protection device is connected in series between a DC bus and a DC load branch of the station DC power supply system, and the active protection device comprises: a dual-tube forward DC / DC converter, a single-chip control circuit, an output diode, and a detection circuit;

[0006] The input end of the dual-tube forward DC / DC converter is connected to a DC power supply, the output end of the dual-tube forward DC / DC converter is connected to the DC load branch through the output diode, the single-chip control circuit is connected to the dual-tube forward DC / DC converter and the detection circuit respectively, and the detection circuit is connected to the DC load branch through the output diode;

[0007] Among them, the detection circuit is used to collect the DC bus voltage data of the DC load branch; the single-chip computer control circuit is used to perform DC bus fault judgment based on the DC bus voltage data, and when it is judged that a DC bus fault exists, control the two-switch forward DC / DC converter to electrically isolate the DC bus and the DC load branch.

[0008] Optionally, the two-switch forward DC / DC converter includes a drive circuit and a high-frequency isolation converter, and the high-frequency isolation converter includes a high-frequency isolation transformer T and a rectifier circuit;

[0009] The driving end of the driving circuit is connected to the single-chip control circuit, the output end of the driving circuit is connected to the first end of the high-frequency isolation transformer T, the first end and the second end of the high-frequency isolation transformer T are connected to the first end of the rectifier circuit, and the second end of the rectifier circuit is connected to the DC load branch;

[0010] The driving circuit is used to drive and control the rectifier circuit to convert the AC voltage at the DC load branch into a DC voltage that cannot pass through the high-frequency isolation transformer T in response to the driving signal sent by the single-chip control circuit.

[0011] Optionally, the driving circuit includes a voltage input terminal U in , energy storage capacitor C t , MOS switch tube Q 1 , MOS switch tube Q 1 , freewheeling diode D 1 , freewheeling diode D 2 ;

[0012] The voltage input terminal U in The first end and the energy storage capacitor C t The first end of the MOS switch tube Q 1 The drain of the MOS switch tube Q 1 The source of is connected to the first end of the high frequency isolation transformer T; the voltage input terminal U in The second end and the energy storage capacitor C t The second end of the MOS switch tube Q 2 The source of the MOS switch tube Q 2 The drain of the MOS switch tube Q is connected to the first end of the high-frequency isolation transformer T; 2 The drain of the freewheeling diode D 1 The input terminal is connected to the freewheeling diode D 1 The output end of the MOS switch tube Q 1 The drain of the MOS switch tube Q 2The source of the freewheeling diode D 2 The input terminal is connected to the freewheeling diode D 2 The output end of the MOS switch tube Q 1 The source of the MOS switch tube Q 1 The gate and the MOS switch tube Q 2 The gate of the drive circuit serves as the driving end of the drive circuit and is connected to the single chip control circuit.

[0013] Optionally, the rectifier circuit includes a rectifier diode D 3 , rectifier diode D 4 , filter inductor L, filter capacitor C 2 , the filter inductor L and the filter capacitor C 2 Construct an LC filter;

[0014] Among them, the rectifier diode D 3 The input end is connected to the first end of the high frequency isolation transformer T, and the rectifier diode D 4 The input end is connected to the second end of the high frequency isolation transformer T, and the rectifier diode D 3 The output terminal and the rectifier diode D 4 The output end of the filter capacitor C is connected to the first end of the filter inductor L, the second end of the filter inductor L is used as the second end of the rectifier circuit, connected to the positive end of the DC bus of the DC load branch, and the filter capacitor C 2 The first end of the filter inductor L is connected to the second end of the filter inductor L, and the rectifier diode D 4 The input terminal and the filter capacitor C 2 The second end of the rectifier circuit is used as the second end of the rectifier circuit and connected to the negative end of the DC bus of the DC load branch.

[0015] Optionally, the detection circuit includes an AC signal sampling circuit and a sampling port;

[0016] The AC signal sampling circuit is connected to the sampling port, and the sampling port is connected to the DC bus positive terminal and the DC bus negative terminal of the DC load branch through the output diode, and is used to collect the DC bus voltage data of the DC load branch and extract the AC voltage from the DC bus voltage data;

[0017] The AC signal sampling circuit is connected to the single-chip control circuit and is used to send the AC voltage to the single-chip control circuit.

[0018] Optionally, the AC signal sampling circuit includes a capacitor C 1 , transformer, resistor R 1 , filtering circuit and AD conversion circuit;

[0019] The input end of the transformer is connected to the capacitor C 1 The output end of the transformer is connected to the positive terminal of the DC bus and the negative terminal of the DC bus of the DC load branch. 1 The input end of the filter circuit is connected to the input end of the AD conversion circuit, and the output end of the AD conversion circuit is connected to the single-chip control circuit;

[0020] Among them, the capacitor C 1 Used to filter out the DC component in the DC bus voltage data to obtain the initial AC voltage; the transformer is used to step down the initial AC voltage, and the filtering circuit is used to filter the initial AC voltage after the step-down process to obtain the final AC voltage; the AD conversion circuit is used to convert the AC voltage into a digital signal and send the converted AC voltage signal to the single-chip control circuit.

[0021] Optionally, the single-chip control circuit is used to use a fast Fourier transform algorithm to calculate the voltage effective value of the AC voltage based on the AC voltage signal, perform a DC bus fault judgment based on the voltage effective value of the AC voltage, and send a signal for controlling the MOS switch tube Q to the dual-tube forward DC / DC converter when it is judged that a DC bus fault exists. 1 and the MOS switch tube Q 1 Disconnected drive signal.

[0022] Optional, active protection device for station DC power supply system, also includes RS-485 communication interface and human-machine interface;

[0023] The RS-485 communication interface is connected to the single-chip control circuit, and the single-chip control circuit is used to send relevant fault information to the outside through the RS-485 communication interface when it is determined that there is a DC bus fault;

[0024] The human-computer interaction interface is connected to the single-chip control circuit, and the single-chip control circuit is used to determine that there is a DC bus fault in the DC load branch when it is judged that the effective value of the AC voltage is greater than the preset AC-to-DC fault alarm value and the duration is greater than the preset duration, and transmit a corresponding alarm signal to the human-computer interaction interface.

[0025] In a second aspect, an active protection method applied to a station DC power supply system is provided. The method is applied to an active protection device of the station DC power supply system. The method includes:

[0026] receiving the DC bus voltage data of the DC load branch collected by the detection circuit;

[0027] Performing DC bus fault judgment based on the DC bus voltage data;

[0028] When it is determined that a DC bus fault exists, the dual-switch forward DC / DC converter is controlled to electrically isolate the DC bus from the DC load branch.

[0029] In a third aspect, a station DC power supply system is provided, comprising: an active protection device applied to a station DC power supply system as described in any one of the first aspects.

[0030] Through the technical solution provided by the present invention, an active protection device and method for a station DC power supply system are provided. The device is connected in series between the DC bus and the DC load branch of the station DC power supply system, and includes: a dual-tube forward DC / DC converter, a single-chip control circuit, an output diode and a detection circuit; the detection circuit is used to collect the DC bus voltage data of the DC load branch; the single-chip control circuit is used to judge the DC bus fault based on the DC bus voltage data, and when it is judged that there is a DC bus fault, the dual-tube forward DC / DC converter is controlled to electrically isolate the DC bus and the DC load branch. In this way, electrical isolation between the DC bus and the DC load branch can be achieved, the fault can be limited to the DC load branch, and the fault can be prevented from expanding to the DC power supply side and other DC load branches connected to the DC bus, so as to achieve electrical isolation between the fault branch and the non-fault branch. In this way, it is possible to prevent the fault from further expanding to the entire station DC power supply system, thereby improving the safety and stability of the station DC power supply system.

[0031] It should be understood that the above general description and the following detailed description are only exemplary and explanatory and cannot limit the present invention. Other features and advantages of the present invention will be described in detail in the following specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 A schematic diagram of a connection method of an active protection device in a station DC power supply system provided in an embodiment of the present application;

[0034] Figure 2 A structural framework diagram of an active protection device applied to a station DC power supply system provided in an embodiment of the present application;

[0035] Figure 3 A circuit diagram of a dual-switch forward DC / DC converter provided in an embodiment of the present application;

[0036] Figure 4 A circuit structure diagram of an AC signal sampling circuit provided in an embodiment of the present application;

[0037] Figure 5 A flowchart of an active protection method for a station DC power supply system provided in an embodiment of the present application;

[0038] Figure 6 A schematic diagram of the structure of an active protection device applied to a station DC power supply system provided in an embodiment of the present application;

[0039] Figure 7 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application;

[0040] In the figure:

[0041] 1-dual-tube forward DC / DC converter, 11-driving circuit, 12-high-frequency isolation converter;

[0042] 2- Single chip microcomputer control circuit;

[0043] 3- Output diode;

[0044] 4-detection circuit, 41-AC signal sampling circuit;

[0045] 5-RS-485 communication interface;

[0046] 6-Human-computer interaction interface;

[0047] 7- DC power supply;

[0048] 8-DC load branch. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0050] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0051] In the substation power supply system, the AC circuit and the DC circuit are two independent systems. The AC circuit is generally a grounded system, while the DC circuit is an ungrounded system. Therefore, when AC leaks into DC, it will cause a DC bus grounding fault.

[0052] The standard DL / T 1392-2014 "Technical Conditions for Insulation Monitoring Devices of DC Power Supply Systems" requires that in a station DC power supply system, when the effective value of the incoming AC voltage is greater than or equal to 10V, the monitoring device should have measurement and alarm functions. Therefore, it is of great significance to realize the functions of active fault isolation, active fault detection, active fault location and equipment protection of the station DC power supply system.

[0053] For DC bus grounding faults caused by AC entering DC, the existing solution is to detect the fault through a portable grounding fault finder, but this method has obvious disadvantages: 1) Due to the low compatibility and poor anti-interference ability of the finder itself, it may cause false alarms of grounding faults; 2) Any feeder branch needs to be tested, which has the disadvantages of large workload and poor timeliness. In addition, a multimeter can be used to remove part of the loop wiring to find the fault, but it is easy to cause accidental touch and contact accidents. More importantly, these instruments or methods cannot effectively limit and quickly isolate the fault, which may cause the fault to further expand to the entire system.

[0054] In order to solve the above technical problems, the inventive concept of the present invention is as follows: Figure 1As shown, the substation power supply system may include multiple DC load branches: DC load branch 1, DC load branch 2, ..., DC load branch n. For each DC load branch connected to the DC bus in the substation power supply system, an active protection device is connected in series between it and the DC bus, such as a new active protection device 1 can be connected in series between DC load branch 1 and the DC bus; a new active protection device 2 can be connected in series between DC load branch 2 and the DC bus; and a new active protection device n can be connected in series between DC load branch n and the DC bus. Among them, the new active protection device 1, the new active protection device 2, ..., the new active protection device n are independent of each other. When a faulty AC power source enters a DC load branch, the active protection device connected in series can be used to cut off the electrical connection between the DC load branch and the DC bus, limit the fault to the DC load branch, prevent the fault from expanding to the DC power supply side and other DC load branches connected to the DC bus, and realize electrical isolation between the fault branch and the non-fault branch. This can prevent the fault from further expanding to the entire station DC power supply system, thereby improving the safety and stability of the station DC power supply system.

[0055] like Figure 2 As shown, the active protection device is mainly composed of a double-tube forward DC / DC converter 1, a single-chip control circuit 2, an output diode 3 and a detection circuit 4. The input end of the double-tube forward DC / DC converter 1 is connected to a DC power supply 7, the output end of the double-tube forward DC / DC converter 1 is connected to a DC load branch 8 through an output diode 3, the single-chip control circuit 2 is respectively connected to the double-tube forward DC / DC converter 1 and the detection circuit 4, and the detection circuit 4 is connected to the DC load branch 8 through the output diode 3; wherein the detection circuit 4 is used to collect the DC bus voltage data of the DC load branch 8; the single-chip control circuit 2 is used to perform a DC bus fault judgment based on the DC bus voltage data, and when it is judged that there is a DC bus fault, control the double-tube forward DC / DC converter 1 to electrically isolate the DC bus and the DC load branch 8.

[0056] The topology of the dual-switch forward DC / DC converter 1 is as follows: Figure 3 As shown, the dual-transistor forward DC / DC converter 1 includes a drive circuit 11 and a high-frequency isolation converter 12. The high-frequency isolation converter 12 includes a high-frequency isolation transformer T and a rectifier diode D 3 , rectifier diode D 4 , filter inductor L, filter capacitor C 2 The rectifier circuit formed; the driving end of the driving circuit 11 (PWM 1 and PWM 2) is connected to the single-chip control circuit 2, the output end of the drive circuit 11 is connected to the first end of the high-frequency isolation transformer T, the first end and the second end of the high-frequency isolation transformer T are connected to the first end of the rectifier circuit, and the second end of the rectifier circuit is connected to the first end of the high-frequency isolation transformer T. 0 wherein the drive circuit 11 is used to respond to the drive signal sent by the single-chip control circuit 2 to drive the control rectifier circuit to convert the AC voltage at the DC load branch 8 into a DC voltage that cannot pass through the high-frequency isolation transformer T.

[0057] Correspondingly, such as Figure 3 As shown, the driving circuit 11 includes a voltage input terminal U in , energy storage capacitor C t , MOS switch tube Q 1 , MOS switch tube Q 1 , freewheeling diode D 1 , freewheeling diode D 2 ; Voltage input terminal U in The first end and the energy storage capacitor C t The first end of the MOS switch tube Q 1 The drain connection of the MOS switch tube Q 1 The source of is connected to the first end of the high-frequency isolation transformer T; the voltage input terminal U in The second end and the energy storage capacitor C t The second end of the MOS switch tube Q 2 The source connection of the MOS switch tube Q 2 The drain of the MOS switch tube Q is connected to the first end of the high-frequency isolation transformer T; 2 The drain and freewheeling diode D 1 The input terminal is connected to the freewheeling diode D 1 The output end of the MOS switch tube Q 1 The drain connection of MOS switch tube Q 2 The source and freewheeling diode D 2 The input terminal is connected to the freewheeling diode D 2 The output end of the MOS switch tube Q 1 The source connection of MOS switch tube Q 1 The gate and MOS switch tube Q 2 The gate of the drive circuit 11 is connected to the single chip control circuit 2 as the driving end.

[0058] In the rectifier circuit of the high-frequency isolation converter 12, the filter inductor L and the filter capacitor C 2 The LC filter is formed. Among them, the rectifier diode D 3 The input end is connected to the first end of the high-frequency isolation transformer T, and the rectifier diode D 4The input end is connected to the second end of the high-frequency isolation transformer T, and the rectifier diode D 3 The output terminal and the rectifier diode D 4 The output end of the filter is connected to the first end of the filter inductor L, and the second end of the filter inductor L is used as the second end of the rectifier circuit to connect the positive end of the DC bus of the DC load branch. The filter capacitor C 2 The first end of the filter inductor L is connected to the second end of the filter inductor L, and the rectifier diode D 4 The input terminal and filter capacitor C 2 The second end of the rectifier circuit is used as the second end of the rectifier circuit and connected to the negative end of the DC bus of the DC load branch.

[0059] Under the circuit structure of the above-mentioned two-switch forward DC / DC converter 1, the active protection device can realize the active fault isolation function. Figure 3 As shown, in actual application, the active protection device is usually connected in series between the DC load branch 8 and the DC bus, and is also located between the DC power supply 7 (battery pack) and the DC load branch 8. The double-tube forward DC / DC converter 1 contains a high-frequency isolation converter 12. When the AC power supply enters the DC load side, the output voltage U 0 On the other side, the faulty AC current flows through the rectifier diode D 3 and D 4 , L and C 2 After the rectifier circuit is formed, it is converted into direct current. Direct current cannot pass through the high-frequency isolation transformer T. Therefore, the electrical isolation of the DC power supply (battery pack) 7 and the DC load branch 8 can be achieved, and the fault can be limited to the DC load branch to prevent the fault from expanding to the DC power supply (battery pack) side and other DC load branches, thereby achieving electrical isolation between the fault branch and the non-fault branch.

[0060] Under the circuit structure of the above-mentioned two-tube forward DC / DC converter 1, the two-tube forward DC / DC converter can also realize the device protection function. Specifically, the single-chip control circuit 2 modulates two drive control signals (PWM) through pulse width modulation (PWM) 1 and PWM 2 ) to control the two metal oxide semiconductor switches (MOS switch tube Q 1 , MOS switch tube Q 2 ) working state. When the single-chip control circuit 2 detects a fault on the DC bus, it will immediately disconnect the PWM switch drive signal of the DC / DC forward converter, turn off the working state of the two MOS tubes, and stop supplying power to the load branch, thereby protecting the load-end equipment.

[0061] PWM switch drive signal PWM 1 and PWM 2The unipolar control mode is adopted. When the system is operating normally, the switch drive signal PWM issued by the microcontroller control circuit 1 and PWM 2 The high level 5V is sent to the MOS tube gate, making the MOS switch tube Q 1 And MOS switch tube Q 2 In the on state; when a fault occurs on the DC load side, the single-chip control circuit 2 detects the fault and sends a switch drive signal PWM 1 and PWM 2 The low level 0V is applied to the gate of the MOS tube, making the two MOS switch tubes Q 1 And MOS switch tube Q 2 It is in the disconnected state, so that the DC power supply side and the DC load side are disconnected, that is, the power supply to the load branch is stopped, thus completing the protection of the load-end equipment.

[0062] In a specific application scenario, the active protection device can also realize the active fault detection function by using the single-chip control circuit 2 and the detection circuit 4. Among them, the detection circuit 4 includes an AC signal sampling circuit 41 and a sampling port; the AC signal sampling circuit 41 is connected to the sampling port, and the sampling port is connected to the DC bus positive terminal and the DC bus negative terminal of the DC load branch 8 through the output diode 3, which is used to collect the DC bus voltage data of the DC load branch 8 and extract the AC voltage from the DC bus voltage data; the AC signal sampling circuit 41 is connected to the single-chip control circuit 2, and is used to send the AC voltage to the single-chip control circuit 2.

[0063] Correspondingly, such as Figure 4As shown, the AC signal sampling circuit 41 includes a capacitor C1, a transformer, a resistor R1, a filter circuit and an AD conversion circuit; the input end of the transformer is connected to the DC bus positive terminal and the DC bus negative terminal of the DC load branch through the capacitor C1, the output end of the transformer is connected to the input end of the filter circuit through the resistor R1, the output end of the filter circuit is connected to the input end of the AD conversion circuit, and the output end of the AD conversion circuit is connected to the single-chip control circuit; wherein the capacitor C1 is used to filter out the DC component in the DC bus voltage data to obtain the initial AC voltage; the transformer is used to step down the initial AC voltage, and the filter circuit is used to filter the initial AC voltage after the step-down process to obtain the final AC voltage; the AD conversion circuit is used to convert the AC voltage into a digital signal and send the converted AC voltage signal to the single-chip control circuit 2. The transformer ratio is 20:1. When the DC power supply system is at most fed with 220V AC, only 11V voltage is available on the secondary side through the transformer ratio, which is not dangerous to the electronic equipment on the secondary side, and its voltage meets the requirements of the power supply of the subsequent power supply. In order to reduce the aliasing frequency components in the collected AC voltage values ​​to a negligible level, the collected AC voltage values ​​should also be filtered by a filtering circuit, and the filtering circuit adopts a second-order anti-aliasing filtering circuit; then it is converted into a digital signal by an AD conversion circuit and output to the single-chip microcomputer control circuit 2, and then the sampling value is analyzed and processed by a software algorithm to obtain the accurate effective value of the incoming AC voltage.

[0064] In a specific application scenario, the single-chip control circuit 2 is used to use a fast Fourier transform algorithm to calculate the voltage effective value of the AC voltage based on the AC voltage signal, and to perform a DC bus fault judgment based on the voltage effective value of the AC voltage. When a DC bus fault is judged, a signal for controlling the MOS switch tube Q is sent to the double-tube forward DC / DC converter. 1 And MOS switch tube Q 2 Disconnected drive signal.

[0065] The software algorithm of the single-chip microcomputer control circuit adopts fast Fourier transform, which is the expression of Fourier transform in the discrete domain. It has low computational requirements and fast computation, and is very suitable for processing digital signals. Its calculation formula is:

[0066]

[0067]

[0068]

[0069]

[0070] In the formula, n represents the harmonic order, N is the number of points sampled in one cycle, k represents the kth sampling point, and is the sampling value of the kth sampling point. n and b n represents the Fourier series coefficient, U n is the effective value of the AC voltage entering, θ n Indicates the Un argument.

[0071] The software algorithm samples and analyzes the collected AC voltage fundamental wave, so it only needs to analyze and calculate the situation when n=1; the AC frequency of the substation is 50Hz, and the period is 0.02s, that is, 20ms; set the number of sampling points in a period N=100, then the above formula can be transformed into:

[0072]

[0073]

[0074]

[0075]

[0076] According to the above formula, when an AC crossover fault occurs in the DC system of the substation, the original AC voltage is collected from the DC system through the capacitor C1, transformer, and resistor R1, and a digital signal is formed through the filter circuit and the AD conversion circuit and output to the single-chip control circuit 2. In the single-chip control circuit, one data is collected every 0.2ms, so 100 data are collected in one cycle. By performing fast Fourier transform on the sampled discrete data sequence, the fundamental amplitude characteristic quantity of the fault AC voltage signal can be calculated, and the analysis of the AC voltage that crosses into the DC system is realized, and the interference of harmonic signals of other frequencies on the AC crossover analysis is successfully avoided.

[0077] like Figure 2 As shown, the active protection device also includes an RS-485 communication interface 5 and a human-machine interface 6; the RS-485 communication interface 5 is connected to the single-chip control circuit 2, and the single-chip control circuit 2 is used to send relevant fault information to the outside through the RS-485 communication interface 5 when it is determined that there is a DC bus fault; the human-machine interface 6 is connected to the single-chip control circuit 2, and the single-chip control circuit 2 is used to determine that there is a DC bus fault in the DC load branch 8 when it is determined that the voltage effective value of the AC voltage is greater than the preset AC-to-DC fault alarm value and the duration is greater than the preset duration, and transmit the corresponding alarm signal to the human-machine interface 6. Among them, the preset AC-to-DC fault alarm value and the preset duration can be set according to the actual application scenario, such as the preset duration can be set to 1s.

[0078] The active fault location function can be realized through the human-machine interface 6 and the single-chip control circuit 2. Specifically, if an AC-to-DC fault occurs in a branch on the DC load side, the active protection device of the branch can send an alarm signal, which is uploaded to the human-machine interface or the remote monitoring room through the communication equipment, thus realizing the rapid location of all load branch faults in an all-round way.

[0079] In summary, the active protection device applied to the station DC power supply system provided by the present invention has the functions of active fault isolation, active fault detection, equipment protection and active fault location. It can realize the electrical isolation between the DC bus and the DC load branch, limit the fault to the DC load branch, prevent the fault from expanding to the DC power supply side and other DC load branches connected to the DC bus, and realize the electrical isolation between the fault branch and the non-fault branch. It can also prevent the fault from further expanding to the entire station DC power supply system, and improve the safety and stability of the station DC power supply system.

[0080] Figure 5 A flowchart of an active protection method for a station DC power supply system provided by an embodiment of the present invention is provided. The method can be performed as follows: Figure 2 The active protection device applied to the station DC power supply system is implemented as shown. Figure 5 As shown, the method may include the following steps:

[0081] Step 510: Receive the DC bus voltage data of the DC load branch collected by the detection circuit.

[0082] In a specific application scenario, the detection circuit can be connected to the DC load branch through an output diode. Specifically, the detection circuit is used to collect the DC bus voltage data of the DC load branch and transmit it to the single-chip microcomputer control circuit for accurate calculation and analysis of the fault-invading AC voltage. Correspondingly, the single-chip microcomputer control circuit can receive the DC bus voltage data of the DC load branch collected by the detection circuit.

[0083] Step 520: Perform DC bus fault determination based on the DC bus voltage data.

[0084] Step 530: When it is determined that a DC bus fault exists, control the dual-switch forward DC / DC converter to electrically isolate the DC bus and the DC load branch.

[0085] In a specific application scenario, the single-chip control circuit 2 uses a fast Fourier transform algorithm to calculate the effective value of the AC voltage based on the AC voltage signal, and performs a DC bus fault judgment based on the effective value of the AC voltage. When a DC bus fault is judged, a signal for controlling the MOS switch tube Q is sent to the dual-tube forward DC / DC converter. 1 And MOS switch tube Q2 The drive signal is disconnected, so that the two MOS switch tubes Q 1 And MOS switch tube Q 2 It is in the disconnected state, so that the DC power supply side and the DC load side are disconnected, that is, the power supply to the load branch is stopped, thus completing the protection of the load-end equipment.

[0086] In summary, the active protection method for station DC power supply system provided by the present application can realize electrical isolation between DC bus and DC load branch, limit fault to the DC load branch, prevent fault from expanding to DC power supply side and other DC load branches connected to DC bus, and realize electrical isolation between fault branch and non-fault branch. It can also prevent fault from further expanding to the entire station DC power supply system, and improve the safety and stability of station DC power supply system.

[0087] Based on the above Figure 5 A detailed description of the active protection method applied to the station DC power supply system is provided, such as Figure 6 As shown, Figure 6 FIG. 1 is a structural block diagram of an active protection device applied to a station DC power supply system according to an exemplary embodiment. Figure 6 As shown, the device comprises:

[0088] The receiving module 610 may be used to receive the DC bus voltage data of the DC load branch collected by the detection circuit;

[0089] A judgment module 620, which can be used to judge a DC bus fault based on the DC bus voltage data;

[0090] The control module 630 can be used to control the dual-switch forward DC / DC converter to electrically isolate the DC bus and the DC load branch when it is determined that a DC bus fault exists.

[0091] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0092] The embodiments of the present application can achieve electrical isolation between the DC bus and the DC load branch, limit the fault to the DC load branch, prevent the fault from expanding to the DC power supply side and other DC load branches connected to the DC bus, and achieve electrical isolation between the fault branch and the non-fault branch. This can prevent the fault from further expanding to the entire station DC power supply system, thereby improving the safety and stability of the station DC power supply system.

[0093] In the above, the active protection device applied to the station DC power supply system of the embodiment of the present invention is described from the perspective of the functional module in combination with the accompanying drawings. It should be understood that the functional module can be implemented in hardware form, can be implemented by instructions in software form, and can also be implemented by a combination of hardware and software modules. Specifically, the steps of the active protection method embodiment applied to the station DC power supply system in the embodiment of the present invention can be completed by the hardware integrated logic circuit and / or software instructions in the processor, and the steps of the active protection method applied to the station DC power supply system applied in combination with the embodiment of the present invention can be directly embodied as a hardware decoding processor to execute, or a combination of hardware and software modules in the decoding processor to execute. Optionally, the software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory, and the processor reads the information in the memory, and completes the steps in the above-mentioned active protection method embodiment applied to the station DC power supply system in combination with its hardware.

[0094] An embodiment of the present invention provides a station DC power supply system, comprising the active protection device applied to the station DC power supply system in any of the above embodiments.

[0095] Figure 7 It is a schematic block diagram of an electronic device 700 according to an embodiment of the present invention.

[0096] like Figure 7 As shown, the electronic device 700 may include:

[0097] The memory 710 and the processor 720, the memory 710 is used to store the computer program and transmit the program code to the processor 720. In other words, the processor 720 can call and run the computer program from the memory 710 to implement the method in the embodiment of the present invention.

[0098] For example, the processor 720 may be configured to execute the above method embodiments according to instructions in the computer program.

[0099] In some embodiments of the present invention, the processor 720 may include but is not limited to:

[0100] General-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0101] In some embodiments of the present invention, the memory 710 includes but is not limited to:

[0102] Volatile memory and / or non-volatile memory. Among them, the non-volatile memory can be read-only memory (ROM), programmable ROM (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM) or flash memory. Volatile memory can be random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link DRAM (SLDRAM), and direct memory bus random access memory (Direct Rambus RAM, DR RAM).

[0103] In some embodiments of the present invention, the computer program may be divided into one or more modules, which are stored in the memory 710 and executed by the processor 720 to complete the method provided by the present invention. The one or more modules may be a series of computer program instruction segments capable of completing specific functions, and the instruction segments are used to describe the execution process of the computer program in the controller.

[0104] like Figure 7 As shown, the electronic device 700 may further include:

[0105] The transceiver 730 may be connected to the processor 720 or the memory 710 .

[0106] The processor 720 may control the transceiver 730 to communicate with other devices, specifically, to send data to other devices or receive data sent by other devices. The transceiver 730 may include a transmitter and a receiver. The transceiver 730 may further include an antenna, and the number of antennas may be one or more.

[0107] It should be understood that the various components in the electronic device are connected via a bus system, wherein the bus system includes not only a data bus but also a power bus, a control bus and a status signal bus.

[0108] The present invention also provides a computer storage medium having a computer program stored thereon, which, when executed by a computer, enables the computer to perform the method of the above method embodiment. In other words, an embodiment of the present invention also provides a computer program product containing instructions, which, when executed by a computer, enables the computer to perform the method of the above method embodiment.

[0109] When software is used for implementation, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function according to the embodiment of the present invention is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions can be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions can be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (Digital Subscriber Line, DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more available media integration. The available medium can be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a digital video disc (Digital Video Disc, DVD)), or a semiconductor medium (e.g., a solid-state drive (Solid State Disk, SSD)), etc.

[0110] Those skilled in the art will appreciate that the modules and algorithm steps of each example described in conjunction with the embodiments applied herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0111] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the module is only a logical function division. There may be other division methods in actual implementation, such as multiple modules or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0112] The modules described as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. For example, each functional module in each embodiment of the present application may be integrated into a processing module, or each module may exist physically separately, or two or more modules may be integrated into one module.

[0113] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in this application, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An active protection device applied to a station DC power supply system, characterized in that: The active protection device is connected in series between the DC bus and the DC load branch of the station DC power supply system, and the active protection device includes: a double-tube forward DC / DC converter, a single-chip control circuit, an output diode and a detection circuit; The input end of the dual-tube forward DC / DC converter is connected to a DC power supply, the output end of the dual-tube forward DC / DC converter is connected to the DC load branch through the output diode, the single-chip control circuit is connected to the dual-tube forward DC / DC converter and the detection circuit respectively, and the detection circuit is connected to the DC load branch through the output diode; Among them, the detection circuit is used to collect the DC bus voltage data of the DC load branch; the single-chip computer control circuit is used to perform DC bus fault judgment based on the DC bus voltage data, and when it is judged that a DC bus fault exists, control the two-switch forward DC / DC converter to electrically isolate the DC bus and the DC load branch.

2. The active protection device for a station DC power supply system according to claim 1, characterized in that: The dual-switch forward DC / DC converter includes a driving circuit and a high-frequency isolation converter, and the high-frequency isolation converter includes a high-frequency isolation transformer T and a rectifier circuit; The driving end of the driving circuit is connected to the single-chip control circuit, the output end of the driving circuit is connected to the first end of the high-frequency isolation transformer T, the first end and the second end of the high-frequency isolation transformer T are connected to the first end of the rectifier circuit, and the second end of the rectifier circuit is connected to the DC load branch; The driving circuit is used to drive and control the rectifier circuit to convert the AC voltage at the DC load branch into a DC voltage that cannot pass through the high-frequency isolation transformer T in response to the driving signal sent by the single-chip control circuit.

3. The active protection device for a station DC power supply system according to claim 2, characterized in that: The driving circuit includes a voltage input terminal U in , energy storage capacitor C t , MOS switch tube Q1, MOS switch tube Q1, freewheeling diode D1, freewheeling diode D2; The voltage input terminal U in The first end and the energy storage capacitor C t The first end of each of the voltage input terminal U is connected to the drain of the MOS switch tube Q1, and the source of the MOS switch tube Q1 is connected to the first end of the high-frequency isolation transformer T; in The second end and the energy storage capacitor C t The second ends of are respectively connected to the source of the MOS switch tube Q2, and the drain of the MOS switch tube Q2 is connected to the first end of the high-frequency isolation transformer T; the drain of the MOS switch tube Q2 is connected to the input end of the freewheeling diode D1, and the output end of the freewheeling diode D1 is connected to the drain of the MOS switch tube Q1; the source of the MOS switch tube Q2 is connected to the input end of the freewheeling diode D2, and the output end of the freewheeling diode D2 is connected to the source of the MOS switch tube Q1; the gate of the MOS switch tube Q1 and the gate of the MOS switch tube Q2 are connected to the single-chip control circuit as the driving end of the driving circuit.

4. The active protection device for a station DC power supply system according to claim 2, characterized in that: The rectifier circuit includes a rectifier diode D3, a rectifier diode D4, a filter inductor L, and a filter capacitor C2, wherein the filter inductor L and the filter capacitor C2 constitute an LC filter; Among them, the input end of the rectifier diode D3 is connected to the first end of the high-frequency isolation transformer T, the input end of the rectifier diode D4 is connected to the second end of the high-frequency isolation transformer T, the output end of the rectifier diode D3 is connected to the output end of the rectifier diode D4 and the first end of the filter inductor L, the second end of the filter inductor L serves as the second end of the rectifier circuit, connected to the positive end of the DC bus of the DC load branch, the first end of the filter capacitor C2 is connected to the second end of the filter inductor L, the input end of the rectifier diode D4 and the second end of the filter capacitor C2 serve as the second end of the rectifier circuit, connected to the negative end of the DC bus of the DC load branch.

5. The active protection device for a station DC power supply system according to claim 1, characterized in that: The detection circuit includes an AC signal sampling circuit and a sampling port; The AC signal sampling circuit is connected to the sampling port, and the sampling port is connected to the DC bus positive terminal and the DC bus negative terminal of the DC load branch through the output diode, and is used to collect the DC bus voltage data of the DC load branch and extract the AC voltage from the DC bus voltage data; The AC signal sampling circuit is connected to the single-chip control circuit and is used to send the AC voltage to the single-chip control circuit.

6. The active protection device for a station DC power supply system according to claim 5, characterized in that: The AC signal sampling circuit includes a capacitor C1, a transformer, a resistor R1, a filter circuit and an AD conversion circuit; The input end of the transformer is connected to the DC bus positive terminal and the DC bus negative terminal of the DC load branch through the capacitor C1, the output end of the transformer is connected to the input end of the filter circuit through the resistor R1, the output end of the filter circuit is connected to the input end of the AD conversion circuit, and the output end of the AD conversion circuit is connected to the single-chip control circuit; Among them, the capacitor C1 is used to filter out the DC component in the DC bus voltage data to obtain the initial AC voltage; the transformer is used to step down the initial AC voltage, and the filtering circuit is used to filter the initial AC voltage after the step-down process to obtain the final AC voltage; the AD conversion circuit is used to convert the AC voltage into a digital signal and send the converted AC voltage signal to the single-chip control circuit.

7. The active protection device applied to a station DC power supply system according to claim 6, characterized in that: The single-chip control circuit is used to adopt a fast Fourier transform algorithm to calculate the effective value of the AC voltage based on the AC voltage signal, and to perform a DC bus fault judgment based on the effective value of the AC voltage. When it is judged that a DC bus fault exists, a drive signal for controlling the MOS switch tube Q1 and disconnecting the MOS switch tube Q1 is sent to the dual-tube forward DC / DC converter.

8. The active protection device applied to a station DC power supply system according to claim 7, characterized in that: It also includes RS-485 communication interface and human-computer interaction interface; The RS-485 communication interface is connected to the single-chip control circuit, and the single-chip control circuit is used to send relevant fault information to the outside through the RS-485 communication interface when it is determined that there is a DC bus fault; The human-computer interaction interface is connected to the single-chip control circuit, and the single-chip control circuit is used to determine that there is a DC bus fault in the DC load branch when it is judged that the effective value of the AC voltage is greater than the preset AC-to-DC fault alarm value and the duration is greater than the preset duration, and transmit a corresponding alarm signal to the human-computer interaction interface.

9. An active protection method applied to a station DC power supply system, characterized in that: The method is applied to the active protection device applied to a station DC power supply system according to any one of claims 1 to 8, and the method comprises: receiving the DC bus voltage data of the DC load branch collected by the detection circuit; Performing DC bus fault judgment based on the DC bus voltage data; When it is determined that a DC bus fault exists, the dual-switch forward DC / DC converter is controlled to electrically isolate the DC bus from the DC load branch.

10. A station DC power supply system, characterized in that: include: An active protection device applied to a station DC power supply system as claimed in any one of claims 1 to 8.

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