Insulation fault detection system and insulation fault detection method

Abstract

The invention relates to an insulation fault detection system and an insulation fault detection method. The system comprises a main insulation monitoring unit, at least one first DC branch, at least one slave insulation monitoring unit, at least one second DC branch and at least one server load. The main insulation monitoring unit is used for acquiring voltage to ground of the bus under different switching resistors, first leakage current corresponding to the first direct current branch and second leakage current corresponding to the second direct current branch; according to the voltage to ground, the first leakage current and the second leakage current, fault detection is carried out on lines among the main insulation monitoring unit, the auxiliary insulation monitoring unit and the server load, and a first detection result is obtained. According to the insulation fault detection system, the main insulation monitoring unit is used for intensively controlling the switching resistor and coordinating data acquisition, so that the insulation fault can be quickly and accurately positioned in a multi-branch and multi-node complex direct-current power supply system.

Description

Technical Field

[0001] This application relates to the field of power detection technology, and in particular to an insulation fault detection system and an insulation fault detection method. Background Technology

[0002] With the widespread application of high-voltage direct current (HVDC) power supply technology in data centers, communication base stations, and other fields, the scale of multi-branch output DC bus systems is becoming increasingly large. This is especially true for applications where multiple power supply units (PSUs) are connected to the back end of the HVDC power supply. Due to the numerous branches in the PSUs, a single system often has dozens to hundreds of DC branches. To ensure the safe and stable operation of the system, it is essential to monitor the insulation safety of the main circuit of the DC bus and each output branch.

[0003] However, the insulation fault detection techniques described in the relevant technologies suffer from low detection efficiency. Summary of the Invention

[0004] Based on this, it is necessary to provide an insulation fault detection system and method to address the aforementioned technical problems. By adopting a main insulation monitoring unit to centrally control the switching resistors and coordinate data acquisition, the system enables rapid and accurate location of insulation faults in complex DC power supply systems with multiple branches and nodes, thereby improving the detection efficiency of insulation faults.

[0005] In a first aspect, this application provides an insulation fault detection system, which includes: a main insulation monitoring unit, at least one first DC branch, at least one slave insulation monitoring unit, at least one second DC branch, and at least one server load; the main insulation monitoring unit is connected to the slave insulation monitoring unit through at least one first DC branch; the slave insulation monitoring unit is connected to the server load through at least one second DC branch; the main insulation monitoring unit, the slave insulation monitoring unit, and the server load are all connected to a busbar;

[0006] The main insulation monitoring unit is used to acquire the ground voltage of the busbar under different switching resistors, the first leakage current of the first DC branch, and the second leakage current of the second DC branch, and to perform fault detection on the line between the main insulation monitoring unit, the slave insulation monitoring unit and the server load based on the ground voltage, the first leakage current and the second leakage current, and to obtain the first detection result.

[0007] In some embodiments, the main insulation monitoring unit includes a first switching circuit, a second switching circuit, a first voltage sampling module, and a second voltage sampling module; the first switching circuit and the first voltage sampling module are connected in parallel, and one end of the first switching circuit and the first voltage sampling module are connected to the positive bus, while the other end is grounded; the second switching circuit and the second voltage sampling module are connected in parallel, and one end of the second switching circuit and the second voltage sampling module are connected to the negative bus, while the other end is grounded;

[0008] The first voltage sampling module is used to collect the first voltage to ground of the positive busbar when the first switching circuit and the second switching circuit are under different switching resistors.

[0009] The second voltage sampling module is used to collect the second voltage to ground of the negative busbar when the first switching circuit and the second switching circuit are under different switching resistors.

[0010] In some embodiments, the first switching circuit includes a first switching resistor and a first switch, and the second switching circuit includes a second switching resistor and a second switch; the first switching resistor is connected in series with the first switch; and the second switching resistor is connected in series with the second switch.

[0011] The first voltage sampling module is used to collect the first switching voltage to ground of the positive bus when the first switch is controlled to be closed and the second switch is controlled to be open; and to collect the third switching voltage to ground of the positive bus when the first switch is controlled to be open and the second switch is controlled to be closed.

[0012] The second voltage sampling module is used to collect the second switching voltage to ground of the negative bus when the first switch is controlled to be closed and the second switch is controlled to be open; and to collect the fourth switching voltage to ground of the negative bus when the first switch is controlled to be open and the second switch is controlled to be closed.

[0013] In some embodiments, the main insulation monitoring unit further includes: a control module; the control module is connected to the first switch and the second switch;

[0014] The control module is used to control the first switch to be in a closed or open state when acquiring the first switching voltage to ground, and to control the second switch to be in a closed or open state when acquiring the second switching voltage to ground.

[0015] In some embodiments, the first DC branch includes a first connection line and a first leakage current sensor, the first leakage current sensor being disposed on the first connection line; the first connection line is connected to the bus.

[0016] In some embodiments, the second DC branch includes a second connection line and a second leakage current sensor, the second leakage current sensor being disposed on the second connection line; the second connection line is connected to the bus.

[0017] In some embodiments, at least one first DC branch includes a main first DC branch and a backup first DC branch; at least one second DC branch includes a main second DC branch and a backup second DC branch.

[0018] In some embodiments, the master insulation monitoring unit and the slave insulation monitoring unit are connected by wired or wireless communication.

[0019] The main insulation monitoring unit is also used to send the bus voltage to ground under different switching resistors to the slave insulation monitoring unit;

[0020] The insulation monitoring unit is used to obtain the first leakage current of the first DC branch and the second leakage current of the second DC branch, and to perform fault detection on the line between the insulation monitoring unit and the server load based on the voltage to ground, the first leakage current and the second leakage current, to obtain a second detection result.

[0021] Secondly, this application also provides an insulation fault detection method, applied to the main insulation monitoring unit of an insulation fault detection system as described in any of the embodiments of the first aspect above, the method comprising:

[0022] Obtain the bus voltage to ground under different switching resistors, the first leakage current of the first DC branch, and the second current of the second DC branch;

[0023] Based on the voltage to ground, the first leakage current, and the second leakage current, fault detection is performed on the lines between the main insulation monitoring unit, the slave insulation monitoring unit, and the server load to obtain the first detection result.

[0024] In some embodiments, fault detection is performed on the line between the main insulation monitoring unit, the slave insulation monitoring unit, and the server load based on the voltage to ground, a first leakage current, and a second leakage current to obtain a first detection result, including:

[0025] Based on the first switching ground voltage and the second switching ground voltage in the ground voltage, determine the first equivalent resistance value and the second equivalent resistance value of the main line connected to the main insulation monitoring unit;

[0026] Based on the first switching voltage to ground, the second switching voltage to ground, and the first leakage current, determine the third and fourth equivalent resistance values ​​of the first DC branch in the first leakage current.

[0027] Based on the first switching voltage to ground, the second switching voltage to ground, and the second leakage current, determine the fifth and sixth equivalent resistance values ​​of the second DC branch in the second leakage current.

[0028] The first detection result is obtained by performing fault detection on the main line based on the first and second equivalent resistance values, on the first DC branch based on the third and fourth equivalent resistance values, and on the second DC branch based on the fifth and sixth equivalent resistance values.

[0029] In some embodiments, determining the first equivalent resistance value and the second equivalent resistance value of the main line connected to the main insulation monitoring unit based on the first switched-to-ground voltage and the second switched-to-ground voltage includes:

[0030] The first main road relationship is determined based on the first switching-to-ground voltage and the second switching-to-ground voltage in the first switching-to-ground voltage.

[0031] The second main road relationship is determined based on the third and fourth switching-to-ground voltages in the second switching-to-ground voltage.

[0032] Based on the first main road relationship and the second main road relationship, determine the first equivalent resistance value and the second equivalent resistance value.

[0033] In some embodiments, the determination of the third and fourth equivalent resistance values ​​of the first DC branch in the first leakage current, based on the first switching voltage to ground, the second switching voltage to ground, and the first leakage current, includes:

[0034] The first branch relationship is determined based on the first switching voltage to ground in the first switching voltage to ground, the second switching voltage to ground, and the first current in the first leakage current;

[0035] The relationship of the second branch is determined based on the third and fourth switching voltages in the second switching voltage and the second current in the first leakage current.

[0036] Based on the first branch relationship and the second branch relationship, determine the third and fourth equivalent resistance values.

[0037] In some embodiments, the fifth and sixth equivalent resistance values ​​of the second DC branch in the second leakage current are determined based on the first switching voltage to ground, the second switching voltage to ground, and the second leakage current, including:

[0038] The relationship of the third branch is determined based on the first switching voltage to ground in the first switching voltage to ground, the second switching voltage to ground, and the third current in the second leakage current.

[0039] The relationship of the fourth branch is determined based on the third switching voltage to ground in the second switching voltage to ground, the fourth switching voltage to ground, and the fourth current in the second leakage current.

[0040] Based on the third and fourth branch relationships, determine the fifth and sixth equivalent resistance values.

[0041] The aforementioned insulation fault detection system and method include: a main insulation monitoring unit, at least one first DC branch, at least one slave insulation monitoring unit, at least one second DC branch, and at least one server load; the main insulation monitoring unit is connected to the slave insulation monitoring unit through at least one first DC branch; the slave insulation monitoring unit is connected to the server load through at least one second DC branch; the main insulation monitoring unit, slave insulation monitoring unit, and server load are all connected to the busbar; the main insulation monitoring unit is used to acquire the busbar's voltage to ground under different switching resistors, the first leakage current corresponding to the first DC branch, and the second leakage current corresponding to the second DC branch, and to perform fault detection on the lines between the main insulation monitoring unit, slave insulation monitoring unit, and server load based on the voltage to ground, first leakage current, and second leakage current, obtaining a first detection result. By using a single main insulation monitoring unit to centrally control the switching resistors and coordinate data acquisition, rapid and accurate location of insulation faults in complex DC power supply systems with multiple branches and nodes is achieved. The system only needs to perform two switching operations to obtain all the voltage and current data required for the insulation status of the entire system and each branch at once, which greatly shortens the detection cycle and avoids signal conflicts and detection delays that may be caused by the disorderly operation of multiple independent detection units. Attached Figure Description

[0042] Figure 1 This is one of the schematic diagrams of the insulation fault detection system in some embodiments;

[0043] Figure 2 These are schematic diagrams of the power system structure in some embodiments;

[0044] Figure 3 This is a second schematic diagram of the insulation fault detection system structure in some embodiments;

[0045] Figure 4 This is the third schematic diagram of the insulation fault detection system structure in some embodiments;

[0046] Figure 5 This is the fourth schematic diagram of the insulation fault detection system in some embodiments;

[0047] Figure 6 This is the fifth schematic diagram of the insulation fault detection system in some embodiments;

[0048] Figure 7This is the sixth schematic diagram of the insulation fault detection system structure in some embodiments;

[0049] Figure 8 This is the seventh schematic diagram of the insulation fault detection system in some embodiments;

[0050] Figure 9 This is the eighth schematic diagram of the insulation fault detection system in some embodiments;

[0051] Figure 10 This is one of the schematic diagrams of the insulation detection coordination mechanism of the insulation fault detection system in some embodiments;

[0052] Figure 11 This is the second schematic diagram of the insulation detection coordination mechanism of the insulation fault detection system in some embodiments;

[0053] Figure 12 This is a schematic diagram of the insulation fault detection method in some embodiments. Detailed Implementation

[0054] In the embodiments of this application, the term "multiple" refers to two or more, and other quantifiers are similar.

[0055] In the embodiments of this application, the term "at least one" means one or more. For example, at least one of A, B and C can represent six situations: A exists alone, B exists alone, C exists alone, A and B exist simultaneously, A and C exist simultaneously, B and C exist simultaneously, and A, B and C exist simultaneously.

[0056] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0057] With the widespread application of high-voltage direct current (HVDC) power supply technology in data centers, communication base stations, and other fields, the scale of multi-branch output DC bus systems is becoming increasingly large. For HVDC power supply products, monitoring the DC bus insulation to ground is a critical function. The insulation resistance values ​​of both the positive and negative DC bus to ground should be checked periodically. If any abnormalities are found, the abnormal branch should be identified and addressed promptly to prevent simultaneous insulation abnormalities to ground or even serious accidents caused by short circuits to ground in the DC bus. In applications where multiple power supply units (HVDC) are connected to multiple power supply units, a single system often has dozens to hundreds of DC branches due to the large number of branches in each unit. To ensure the safe and stable operation of the system, monitoring the insulation safety of the main DC bus circuit and each output branch is essential. Currently, insulation testing to ground mainly relies on manual inspection to identify branches with abnormal insulation resistance. However, this insulation fault detection technology suffers from low detection efficiency.

[0058] In view of this, this application proposes an insulation fault detection system and an insulation fault detection method. By adopting a main insulation monitoring unit to centrally control the switching resistor and coordinate data acquisition, the system achieves rapid and accurate location of insulation faults in complex DC power supply systems with multiple branches and nodes.

[0059] It should be noted that the beneficial effects or technical problems solved by the embodiments of this application are not limited to this one, but may also be other implicit or related problems. For details, please refer to the description of the embodiments below.

[0060] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0061] In some embodiments, such as Figure 1 As shown, an insulation fault detection system is provided, which includes: a main insulation monitoring unit 10, at least one first DC branch 20, at least one slave insulation monitoring unit 30, at least one second DC branch 40, and at least one server load 50.

[0062] The main insulation monitoring unit is connected to the slave insulation monitoring unit through at least one first DC branch; the slave insulation monitoring unit is connected to the server load through at least one second DC branch; the main insulation monitoring unit, the slave insulation monitoring unit, and the server load are all connected to the bus.

[0063] For example, the above-mentioned insulation fault detection system is applied to a high-voltage DC power supply system, such as... Figure 2 The power system block diagram shown includes a high-voltage direct current (HVDC) power supply system, which is connected to multiple row-head cabinets (such as...) via multiple branches. Figure 2 The diagram shows column headers 1, 2, ..., n, each connecting multiple server loads (three are shown in the diagram, but there are actually two or more). The main insulation monitoring unit is located within the high-voltage direct current (HVDC) power supply system, while the secondary insulation monitoring units are located within the column headers. The line between the HVDC power supply system and the multiple column headers is the main line, the line between the HVDC power supply system and the multiple column headers is the first DC branch, and the line between the column headers and the multiple server loads is the second DC branch.

[0064] The main insulation monitoring unit is used to acquire the ground voltage of the bus under different switching resistors, the first leakage current of the first DC branch, and the second leakage current of the second DC branch. Based on the ground voltage, the first leakage current, and the second leakage current, the main insulation monitoring unit, the slave insulation monitoring unit, and the server load are used to perform fault detection on the line and obtain the first detection result.

[0065] The aforementioned "voltage to ground under different switching resistors" includes at least the first set of positive busbar voltage to ground U1 and negative busbar voltage to ground U2 measured when the positive busbar switching resistor is connected, and the second set of positive busbar voltage to ground U3 and negative busbar voltage to ground U4 measured when the negative busbar switching resistor is connected.

[0066] The aforementioned "first leakage current corresponding to the first DC branch" refers to the current value measured by the leakage current sensor installed on the first DC branch under the above two switching states, which can be denoted as I1_A and I2_A.

[0067] The aforementioned "second leakage current corresponding to the second DC branch" refers to the current value measured by the leakage current sensor installed on the second DC branch under the two switching states mentioned above, which can be denoted as I1_B and I2_B.

[0068] The aforementioned "first detection result" is a comprehensive judgment result of the system on the overall insulation status of the DC bus between the main insulation monitoring unit, the slave insulation monitoring unit, and the server load, as well as the insulation status of its branches (main line, first DC branch, and second DC branch). Specifically, it may include the equivalent resistance of the main line, the equivalent resistance of the first DC branch, and the equivalent resistance of the second DC branch. Furthermore, it may also include whether the main line is faulty; if the main line is faulty, it may further include the identifiers of the faulty first DC branch and the faulty second DC branch.

[0069] The working principle of the insulation fault detection system in this embodiment is as follows: First, after receiving the instruction to start insulation detection (such as timed triggering, manual triggering, or upper-level system instruction triggering), the main insulation monitoring unit controls its built-in switching switch to perform the first switching operation. After waiting for a preset delay time T (this time T is used to overcome the bus distributed capacitance effect and stabilize the voltage), the positive bus-to-ground voltage U1 and the negative bus-to-ground voltage U2 are collected and recorded. Simultaneously, the main insulation monitoring unit sends instructions to each slave insulation monitoring unit via a communication bus (such as CAN, RS485, or Ethernet), instructing them to synchronously collect and report the leakage current value (second leakage current) of their respective associated second DC branch. The main insulation monitoring unit also simultaneously collects leakage current sensor data (first leakage current) from its associated first DC branch. Then, the main insulation monitoring unit controls its built-in switching switch to perform the second switching operation. After waiting for the delay time T again, the positive bus voltage to ground U3 and the negative bus voltage to ground U4 are collected and recorded. The leakage current values ​​of all first DC branches and all second DC branches are collected again synchronously.

[0070] Subsequently, the main insulation monitoring unit calculates the equivalent resistance of the main line by substituting the recorded two sets of bus-to-ground voltages U1, U2, U3, and U4 into the pre-stored calculation formula, specifically including the total positive-to-ground insulation resistance Rp and negative-to-ground insulation resistance Rn of the bus.

[0071] Next, for any branch to be tested (whether it is the first DC branch or the second DC branch), the main insulation monitoring unit uses the leakage current value measured by the branch in the two switching states (for the second DC branch, this value is reported by the slave insulation monitoring unit; for the first DC branch, this value is collected by itself) and four sets of voltage values ​​U1-U4, and substitutes them into the branch insulation resistance calculation formula to calculate the equivalent resistance of the first DC branch (the positive insulation resistance to ground Rdp and the negative insulation resistance to ground Rdn of the first DC branch) and the equivalent resistance of the second DC branch (the positive insulation resistance to ground Rddp and the negative insulation resistance to ground Rddn of the second DC branch).

[0072] Finally, the main insulation monitoring unit compares the calculated total bus insulation resistances Rp and Rn with preset bus insulation thresholds. Simultaneously, it compares the calculated Rdp and Rdn for each first DC branch with preset first branch insulation thresholds, and the calculated Rddp and Rddn for each second DC branch with preset second branch insulation thresholds. Based on the comparison results, a first detection result is generated. This result indicates at least: whether the overall bus insulation is normal; if abnormal, whether the problem is on the positive or negative bus side; which specific first or second DC branches have insulation faults; and the specific value of the insulation resistance of the faulty branch, in order to accurately locate the fault point.

[0073] The insulation fault detection system provided in this application achieves rapid and accurate location of insulation faults in complex DC power supply systems with multiple branches and nodes by employing a main insulation monitoring unit to centrally control the switching resistors and coordinate data acquisition. The system only needs to perform two switching operations to acquire all the voltage and current data required for the insulation status of the entire system and each branch at once, greatly shortening the detection cycle and avoiding signal conflicts and detection delays that may result from the disordered operation of multiple independent detection units.

[0074] In some embodiments, such as Figure 3 As shown, the main insulation monitoring unit includes a first switching circuit, a second switching circuit, a first voltage sampling module 101, and a second voltage sampling module 102.

[0075] The first switching circuit is connected in parallel with the first voltage sampling module, and one end (i.e., the positive input terminal) of the first switching circuit and the first voltage sampling module is connected to the positive bus, while the other end (i.e., the negative input terminal) is grounded; the second switching circuit is connected in parallel with the second voltage sampling module, and one end (i.e., the positive input terminal) of the second switching circuit and the second voltage sampling module is connected to the negative bus, while the other end (i.e., the negative input terminal) is grounded.

[0076] The first voltage sampling module is used to acquire the first voltage to ground of the positive busbar when the first switching circuit and the second switching circuit are operating with different switching resistors. The second voltage sampling module is used to acquire the second voltage to ground of the negative busbar when the first switching circuit and the second switching circuit are operating with different switching resistors.

[0077] Furthermore, the first switching circuit includes a first switching resistor Rtq+ and a first switch K1, and the second switching circuit includes a second switching resistor Rtq- and a second switch K2. The first switching resistor is connected to the first switch (specifically, it is connected in series between the positive bus (DC+) and ground (PE), and the second switching resistor is connected in series with the second switch (specifically, it is connected in series between the negative bus (DC-) and ground (PE).

[0078] The first switching resistor and the second switching resistor have the same resistance value, both ranging from tens to hundreds of kilohms, and are used to form a known detection load; the first switch is used to control the on / off state of the first switching circuit, and the second switch is used to control the on / off state of the second switching circuit.

[0079] Correspondingly, the first voltage sampling module is used to acquire the first switching-to-ground voltage U1 of the positive bus when the first switch is controlled to be closed and the second switch is controlled to be open; and to acquire the third switching-to-ground voltage U3 of the positive bus when the first switch is controlled to be open and the second switch is controlled to be closed. Correspondingly, the second voltage sampling module is used to acquire the second switching-to-ground voltage U2 of the negative bus when the first switch is controlled to be closed and the second switch is controlled to be open; and to acquire the fourth switching-to-ground voltage U4 of the negative bus when the first switch is controlled to be open and the second switch is controlled to be closed. The first and second voltage sampling modules can be high-precision differential ADCs or voltage sampling circuits.

[0080] Furthermore, the aforementioned main insulation monitoring unit also includes a control module 103.

[0081] The control module is connected to the first switch and the second switch. The control module can be a microcontroller unit (MCU), a digital signal processor (DSP), or a programmable logic device (PLC), etc., and its output port is connected to the control terminals of the first switch in the first switching circuit and the second switch in the second switching circuit through a drive circuit (such as optocoupler isolation or transistor drive).

[0082] The working principle of the insulation fault detection system in this embodiment is as follows: First, the first measurement cycle is initiated. The control module sends a command to the drive circuit to close the first switch while keeping the second switch open. This operation connects the first switching resistor to the positive bus to ground loop, changing the system's ground impedance network. At this time, due to the presence of the DC bus to ground distributed capacitance, the bus to ground voltage will undergo a transient change. In order to obtain a stable and accurate voltage value, after issuing the switch action command, the control module starts an internal timer and enters a preset delay waiting stage. The delay time T is set according to the system bus capacitance, resistance parameters, and stability requirements, and is usually a few seconds to tens of seconds. After the delay ends, the control module considers the voltage to be stable and then sends a sampling trigger signal to the first voltage sampling module and the second voltage sampling module. The first voltage sampling module responds to the trigger, measures and outputs the positive bus to ground voltage value at this moment, i.e., the first switched ground voltage U1; the second voltage sampling module responds synchronously, measures and outputs the negative bus to ground voltage value at this moment, i.e., the second switched ground voltage U2. The control module reads and stores the two voltage values ​​(U1 and U2) through the ADC interface or communication interface of the first voltage sampling module and the second voltage sampling module.

[0083] Subsequently, the second measurement cycle is initiated. The control module issues a command to open the first switch and simultaneously close the second switch. This operation disconnects the first switching resistor from the positive bus circuit and connects the second switching resistor to the negative bus-to-ground circuit, creating an alternative ground impedance network state. Similarly, the control module initiates the same delay period T after the switch action. After the delay, the first and second voltage sampling modules are triggered again to sample. At this time, the first voltage sampling module measures and outputs the third switching-to-ground voltage U3; the second voltage sampling module measures and outputs the fourth switching-to-ground voltage U4. The control module also reads and stores these two voltage values ​​(U3 and U4).

[0084] Throughout the process, the control module strictly adheres to the timing logic of "switching action - delay stabilization - trigger sampling," ensuring that the two measurement cycles are completely independent and orderly, and that each sampled voltage value is obtained only after the corresponding ground network has reached a steady state. This controlled, time-division multiplexing operation mode avoids signal interference, instantaneous overshoot, or measurement uncertainties caused by multiple switching resistors being connected simultaneously or asynchronous switching actions. Furthermore, the control module manages the acquired voltage data (U1, U2, U3, U4), transmitting it to internal or external computing units for insulation resistance analysis. Based on the analysis results or external commands, it can control the switch states to reset (all disconnected), restoring the system to normal insulation monitoring standby state.

[0085] The system described in this application, through the establishment of a dedicated control module, achieves precise, reliable, and timing-controllable operation of the switching state. This not only ensures the accurate establishment of the two specific electrical states required for insulation testing but also effectively overcomes the influence of DC bus distributed capacitance on voltage measurement stability by introducing an adjustable delay mechanism, thereby obtaining high-precision U1-U4 voltage data. This design automates and standardizes the entire insulation testing process, reduces the complexity of manual intervention or external timing coordination, improves the repeatability and accuracy of testing, and lays a solid technical foundation for subsequent accurate calculation of insulation resistance.

[0086] In some embodiments, such as Figure 3 As shown, the first DC branch 20 includes a first connecting line 201 and a first leakage current sensor 202; the first leakage current sensor is disposed on the first connecting line, which is connected to the bus. The second DC branch 30 includes a second connecting line 301 and a second leakage current sensor 302; the second leakage current sensor is disposed on the second connecting line, which is connected to the bus. Each first DC branch and each second DC branch are electrically connected to the positive and negative terminals of the DC bus through their corresponding connecting lines, forming a complete power supply loop. Simultaneously, the installation of the first and second leakage current sensors allows the system to monitor the independent ground insulation status of the main line and each branch line separately. It should be noted that... Figure 3 The connection method of the main line, the first DC branch and the second DC branch to the bus, as well as the number of the first DC branch and the second DC branch, are only illustrative examples. In actual applications, the connection method and the number of branches are not limited.

[0087] The aforementioned first DC branch refers to a DC power supply trunk line extending from the output end of the main insulation monitoring unit to one or more DC power supply trunk lines from the input end of the insulation monitoring unit.

[0088] The aforementioned first connection line is a physical conductor or busbar carrying DC power, with one end connected to the busbar (i.e., the positive and negative busbars of the voltage sampling connection of the main insulation monitoring unit) and the other end connected to the power input terminal of the slave insulation monitoring unit. The first connection line is responsible for transmitting the main load current.

[0089] The aforementioned first leakage current sensor, sleeved or connected in series with the first connection line, is used for non-contact or series detection of the total leakage current to ground flowing through the first connection line. The first leakage current sensor can be a high-sensitivity Hall current sensor, a current transformer, or a dedicated leakage current detection integrated circuit, capable of accurately measuring minute leakage currents in the milliampere or even microampere range. The output signal of the first leakage current sensor is connected to the analog input or dedicated detection interface of the main insulation monitoring unit.

[0090] The aforementioned second DC branch refers to a DC power supply branch extending from the voltage sampling input terminal of the insulation monitoring unit to the corresponding server load input terminal. Its structure is similar to that of the first DC branch.

[0091] The aforementioned second connection line is a physical conductor carrying DC power, with one end connected to the busbar (the positive and negative busbars distributed inside the column cabinet) and the other end connected to the server load.

[0092] The aforementioned second leakage current sensor, sleeved or connected in series with the second connection line, is used to detect the ground leakage current of that specific branch line. Its model, principle, and accuracy requirements can be similar to the first leakage current sensor or adjusted according to the branch's rated current. The output signal of the second leakage current sensor is connected to the detection interface of its associated insulation monitoring unit.

[0093] The working principle of the insulation fault detection system in this embodiment is as follows: During the two switching measurements coordinated by the main insulation monitoring unit (corresponding to the acquisition of U1, U2, U3, and U4), the main insulation monitoring unit not only synchronously triggers its own first voltage sampling module and second voltage sampling module, but also commands its own connected first leakage current sensor and all online slave insulation monitoring units to synchronously start their connected second leakage current sensors for sampling through internal instructions or communication bus.

[0094] Leakage current acquisition in the first switching state (K1 closed, K2 open): In this state, the main insulation monitoring unit records the leakage current value (first current) measured by the first leakage current sensor on each first DC branch, denoted as I1_1, I1_2, ..., I1_N, where N represents the number of the Nth branch. Simultaneously, each slave insulation monitoring unit records the leakage current value (third current) measured by the second leakage current sensor on each second DC branch it manages, denoted as I1_branch1, I1_branch2, ..., I1_branchN respectively.

[0095] Leakage current acquisition in the second switching state (K1 open, K2 closed): In this state, the main insulation monitoring unit again acquires and records the value of the first leakage current sensor (second current), denoted as I2_1, I2_2, ..., I2_N. Each slave insulation monitoring unit also again acquires and records the leakage current value of each of its second branches (fourth current), denoted as I2_branch1, I2_branch2, ..., I2_branchN respectively.

[0096] All branch leakage current data (I1_branchX, I2_branchX) collected from the insulation monitoring unit are reported to the main insulation monitoring unit in real time or near real time via communication networks (such as CAN, RS485, Ethernet). The main insulation monitoring unit, as the data aggregation and processing center, ultimately obtains a complete detection dataset: two sets of bus-to-ground voltages (U1, U2, U3, U4) and two sets of corresponding full-system branch leakage currents (I1_X, I2_X; I1_branchX, I2_branchX).

[0097] Subsequently, the main insulation monitoring unit uses a pre-set set of equations containing voltage and leakage current variables to calculate the following: Main line insulation: Using U1-U4, calculate the positive and negative insulation resistances to ground of the main line (including the positive insulation resistance Rp and the negative insulation resistance Rn). First DC branch insulation: Using U1-U4, I1_X, and I2_X, calculate the positive and negative insulation resistances to ground of the first DC branch (including the positive insulation resistance Rdp and the negative insulation resistance Rdn). Second DC branch insulation: Using the same U1-U4 and the corresponding I1_branchX and I2_branchX for this branch, calculate the positive and negative insulation resistances to ground of the second DC branch (including the positive insulation resistance Rddp and the negative insulation resistance Rddn).

[0098] The system described in this application constructs a multi-layered, high-resolution insulation monitoring network by deploying independent leakage current sensors on each critical power supply path (main trunk and branches). This system can not only assess the overall insulation level of the system through bus voltage measurement, but also refine the location accuracy of insulation faults to each specific DC branch. This solves the problem in complex multi-branch systems where the overall insulation resistance decrease alone cannot determine the specific location of the fault. Combined with a master-slave collaborative synchronous sampling mechanism, the system can simultaneously complete the insulation status assessment of the entire system and all branch lines within a single detection cycle, achieving a balance between efficiency and accuracy.

[0099] In some embodiments, such as Figure 4 As shown, the at least one first DC branch includes a main first DC branch and a backup first DC branch; the at least one second DC branch includes a main second DC branch and a backup second DC branch. It should be noted that... Figure 4 The way the first DC branch and the second DC branch are connected to the bus and the number of the first DC branch and the second DC branch are only illustrative examples. In actual applications, the connection method and the number of branches are not limited. Figure 4 The diagram only shows the main first DC branch and the backup first DC branch. In actual applications, a main second DC branch and a backup second DC branch can also be set.

[0100] The aforementioned main first DC branch, serving as the main power transmission channel during normal system operation, typically bears the main load current in its connecting lines and is equipped with a corresponding first main leakage current sensor. Figure 4 Its installation and function are the same as the first leakage current sensor in the aforementioned embodiment.

[0101] The aforementioned backup first DC branch serves as a hot or cold backup channel for the main first DC branch. It is usually the same or similar to the main branch in terms of physical path and cable specifications. When the main branch is in normal operation, it may be in an unloaded, lightly loaded, or standby state, but its connection line remains connected to the busbar and is also equipped with a first backup leakage current sensor.

[0102] The aforementioned main second DC branch and backup second DC branch are configured at the power supply end from the insulation monitoring unit to the server load. The main second DC branch is the branch line that supplies power to the load during normal operation, and its second main leakage current sensor continuously monitors the leakage current of this line. The backup second DC branch is a redundant backup line that can be switched on in case of a failure of the main line, and it is also equipped with a second backup leakage current sensor.

[0103] The aforementioned main DC branch and backup DC branch are all connected to the positive and negative terminals of the DC bus through their connecting lines (main / backup), forming a parallel or switchable power supply network. The outputs of all main leakage current sensors and backup leakage current sensors are connected to the corresponding insulation monitoring units (main branches correspond to the main insulation monitoring unit, and branch lines correspond to the slave insulation monitoring unit).

[0104] The working principle of the insulation fault detection system in this embodiment is as follows: During stable system operation, regardless of whether the main and backup branches are currently under load, the main insulation monitoring unit and each slave insulation monitoring unit can synchronously collect data from the leakage current sensors on all the main and backup DC branches under their management according to a preset cycle. During the two switching states of the resistors, not only the leakage current of the main branch is collected, but also the leakage current of each service branch is collected simultaneously. Combined with the bus-to-ground voltages U1-U4, the insulation resistance to ground of each main and backup branch can be calculated separately. This method achieves a "panoramic" monitoring of the insulation status of the entire power supply path, enabling early detection of potential insulation degradation risks even if the backup line is not currently in use, thus facilitating preventative maintenance.

[0105] When the system detects that the insulation resistance of a main DC branch (such as the first main DC branch or a second main DC branch) is lower than the threshold and determines that a fault has occurred, the system's power management unit (such as an STS static transfer switch or controller) may perform a switching operation to transfer the load from the faulty main branch to the normal backup branch for subsequent fault detection.

[0106] The system described in this application, by extending insulation monitoring capabilities to all primary and backup power supply channels, achieves "full-path, no-dead-angle" visualization of the insulation status of the power supply system, greatly improving the accuracy and breadth of fault location.

[0107] In some embodiments, the master insulation monitoring unit and the slave insulation monitoring unit are connected via wired or wireless communication. Wired communication may include industrial fieldbuses (such as CAN bus, RS-485 bus), Ethernet (including industrial Ethernet protocol), power line carrier (PLC), etc. Wireless communication may include wireless local area networks (Wi-Fi), low-power wide area networks (such as LoRa, NB-IoT), short-range wireless networks (such as ZigBee, Bluetooth Mesh), etc. Both the master and slave units integrate corresponding communication interface modules and protocol stacks to support the connection.

[0108] The main insulation monitoring unit is also used to send the bus voltage to ground under different switching resistors to the slave insulation monitoring unit;

[0109] The insulation monitoring unit is used to obtain the first leakage current of the first DC branch and the second leakage current of the second DC branch, and to perform fault detection on the line between the insulation monitoring unit and the server load based on the voltage to ground, the first leakage current and the second leakage current, to obtain a second detection result.

[0110] The working principle of the insulation fault detection system in this embodiment is as follows: After the main insulation monitoring unit completes two switching operations and successfully collects two sets of bus-to-ground voltages (U1, U2) and (U3, U4), it will broadcast or multicast these key voltage data through the communication network.

[0111] All online slave insulation monitoring units listen to this communication network and receive this voltage data packet. After each slave unit independently verifies the validity of the data, it stores the four sets of voltage values ​​U1, U2, U3, and U4 in its local memory.

[0112] Simultaneously or subsequently, the insulation monitoring unit can collect local leakage current data. Specifically, this includes: a. Leakage current of the first DC branch: collecting data from the first leakage current sensor installed on the first DC branch connected to its input terminal. In the state corresponding to the U1 / U2 collection time, the leakage current value (first current) of that branch is collected, denoted as I1_X; in the state corresponding to the U3 / U4 collection time, the leakage current value (second current) of that branch is collected again, denoted as I2_X. b. Leakage current of each second DC branch: synchronously collecting data from the second leakage current sensor installed on each second DC branch under its management, obtaining the leakage current values ​​(third current and fourth current) of each branch in two states: I1_branch_X and I2_branch_X (where X is the branch number).

[0113] Each slave insulation monitoring unit integrates the same insulation resistance calculation logic or firmware as the master unit locally. Using the common voltage data (U1-U4) received from the master unit and its own locally collected leakage current data, the slave unit can independently perform the following calculations and judgments: a. Main line (first DC branch) insulation assessment: Using (U1, U2, U3, U4) and (I1I2), calculate the positive and negative insulation resistance values ​​(Rdp, Rdn) of the first DC branch it connects to (i.e., the main line from the high-voltage DC cabinet to the head cabinet), and determine whether they are below a preset threshold. b. Branch line (each second DC branch) insulation assessment: For each second DC branch it manages, using the same voltage data (U1-U4) and the branch-specific leakage current data (I1_branch_X, I2_branch_X), calculate the positive and negative insulation resistance values ​​(Rddp, Rddn) of that branch line, and perform threshold judgments for each.

[0114] Based on the above calculations, the slave insulation monitoring unit generates a local second detection result. This result includes at least: the insulation status (normal / fault, and resistance value) of its first DC branch at the input terminal; the insulation status (normal / fault, and resistance value) of each of its subordinate second DC branches; possible timestamps, unit identifiers, and result confidence levels. After generating the second detection result, the slave insulation monitoring unit can proactively or in response to queries from the master unit, reporting its second detection result to the master insulation monitoring unit via the communication network. The master insulation monitoring unit aggregates the second detection results from all slave units and combines them with its own assessment of the entire busbar and main lines (first detection result) to form a complete, hierarchical panoramic view of the insulation status covering the entire power supply system.

[0115] The system described in this application implements a highly efficient and flexible collaborative detection architecture by sharing key bus voltage data between master and slave units and granting slave units independent computing capabilities. This method effectively distributes the computational burden on the central processing unit, and its advantages are particularly evident in large-scale, multi-branch systems, avoiding the data bandwidth and processing latency problems caused by aggregating all sensor data to a single point.

[0116] In summary, based on all the above embodiments, an insulation fault detection system is also provided, such as... Figure 5 As shown, the system includes an HVDC side and a rack-end cabinet side. The HVDC side includes an insulation monitoring unit within the HVDC, a main first DC branch ("DC branch 1" on the left of the diagram), a backup first DC branch ("DC branch 2" on the right of the diagram), and a voltage sampling module. Both the main and backup first DC branches are equipped with leakage current sensors. The rack-end cabinet side includes an insulation monitoring unit within the rack-end cabinet, a main second DC branch ("DC branch 1-1...DC branch 1-n" on the left of the diagram), and backup second DC branches ("DC branch 2-1...DC branch 2-n" on the right of the diagram). Each main second DC branch and each backup second DC branch is equipped with a leakage current sensor, and all are connected to the server load. The insulation monitoring unit in the HVDC is connected to the insulation monitoring unit within the rack-end cabinet via a CAN bus.

[0117] The insulation fault detection system in this embodiment of the application performs the following specific insulation fault process:

[0118] 1. Calculation principle of busbar insulation resistance detection

[0119] To achieve insulation detection resistance, a positive busbar-to-ground switching resistor Rtq+ and a negative busbar-to-ground switching resistor Rtq- are installed. For ease of calculation, let Rtq+=Rtq-=Rtq, that is, both switching resistors are Rtq, with an exemplary value of several hundred kilohms.

[0120] like Figure 6 As shown, during the first switch, K1 is closed, K2 is open, and the ground-connected resistor Rtq is connected. The voltage of the positive busbar to ground is measured as U1, and the voltage of the negative busbar to ground is measured as U2 (both U1 and U2 are positive values).

[0121] like Figure 7 As shown, during the second switch, K1 is disconnected, K2 is closed, and the negative-to-ground switching resistor Rtq is connected. The voltage of the positive bus to ground is measured as U3, and the voltage of the negative bus to ground is measured as U4 (both U3 and U4 are positive values).

[0122] During the first switching, the total resistance of the positive busbar to ground is Rp in parallel with Rtq, and the total resistance of the negative busbar to ground is Rn. Formula (1) can be determined:

[0123] (1)

[0124] During the second switching, the total resistance of the positive busbar to ground is Rp, and the total resistance of the negative busbar to ground is Rn connected in parallel with Rtq. Formula (2) can be determined:

[0125] (2)

[0126] By combining formulas (1) and (2), the insulation resistance values ​​of the positive and negative busbars to ground can be calculated respectively:

[0127]

[0128]

[0129] If the insulation resistance Rp and Rn of the busbar to ground are lower than the set normal threshold, the insulation resistance of the DC busbar to ground is determined to be abnormal.

[0130] 2. Calculation principle for branch circuit insulation resistance testing

[0131] After the busbar insulation resistance to ground is calculated, it is generally necessary to calculate the insulation resistance to ground of each branch. Taking one branch as an example, the steps are as follows:

[0132] like Figure 8 As shown, during the first switch, K1 is closed and K2 is open, the ground-connected resistor Rtq is connected, the voltage of the positive bus to ground is measured as U1, the voltage of the negative bus to ground is measured as U2 (both U1 and U2 are positive values), and the leakage current value of the leakage current sensor of this branch is measured as I1.

[0133] like Figure 9 As shown, during the second switch, K1 is disconnected and K2 is closed, the negative-to-ground switching resistor Rtq is connected, the positive bus voltage to ground is measured as U3, the negative bus voltage to ground is measured as U4 (both U3 and U4 are positive values), and the leakage current value of the leakage current sensor of this branch is measured as I2.

[0134] Taking a branch as an example, let the positive resistance of the branch to ground be Rdp and the negative resistance of the branch to ground be Rdn. The calculation formula can be derived as follows:

[0135] During the first switching, the branch leakage current sensor output value is I1, which indicates that:

[0136] I1 = I1p - I1n, which can be expanded to determine formula (3):

[0137] (3)

[0138] During the second switching, the branch leakage current sensor output value is I2, indicating that:

[0139] I² = I²p - I²n, which can be expanded to determine formula (4):

[0140] (4)

[0141] By combining formulas (3) and (4), the insulation resistance values ​​of the positive and negative busbars to ground of this branch can be calculated respectively:

[0142]

[0143]

[0144] If the insulation resistance to ground of a branch, Rdp and Rdn, is lower than the set normal threshold, then the insulation resistance to ground of that branch is considered abnormal. Similarly, the insulation resistance to ground of all other branches can be calculated using this method. Likewise, the insulation resistance to ground (Rddp and Rddn) of the second DC output circuit can be calculated using this method.

[0145] 3. Insulation testing coordination mechanism

[0146] The insulation resistance calculations above are based on the working state of a single insulation monitoring unit. When multiple rack-mounted power supplies are connected to the back end of a high-voltage DC power supply, if it is necessary to monitor the insulation status to ground of each branch, an insulation monitoring unit can be installed on the high-voltage DC power supply and each rack-mounted power supply. Multiple insulation monitoring units can be installed on the same DC bus.

[0147] Since insulation monitoring requires switching the resistance to ground, multiple insulation monitoring units should have a coordination mechanism in place to ensure they can perform insulation monitoring independently. Specifically, there are two coordination mechanisms:

[0148] like Figure 10 As shown, the first coordination detection mechanism involves interconnecting the insulation monitoring unit of the HVDC and the insulation monitoring unit of the cabinet head unit via a communication line. The specific process of this coordination mechanism is as follows:

[0149] The HVDC insulation monitoring unit operates by twice switching between calculating the busbar-to-ground resistance and the insulation resistance of each branch to determine if any branches are abnormal. If an abnormal branch is found, work instructions are sequentially issued to the head unit according to the abnormal branch number. The head unit's insulation monitoring unit calculates and uploads the abnormal branch's insulation information to the HVDC insulation monitoring unit. It then checks if the abnormal branch polling is complete. If complete, the HVDC summarizes the insulation information and reports it. If not, it returns to the previous cycle of issuing work instructions to the head unit according to the abnormal branch number. If no abnormal branches are found, the HVDC summarizes the insulation information and reports it.

[0150] like Figure 11As shown, the second coordinated detection mechanism uses the HVDC insulation monitoring unit as the main insulation detection unit, which has a built-in bus-to-ground switching insulation monitoring resistor. The insulation monitoring units of each row head cabinet are slave insulation detection units, which do not have a built-in bus-to-ground switching insulation monitoring resistor, or the insulation monitoring resistor is not connected to the ground. The specific process of this coordinated mechanism is as follows:

[0151] The HVDC insulation monitoring unit confirms the communication status with the column head unit insulation monitoring unit, determining whether all column head units are communicating normally. If not all column head units are communicating normally, the monitoring process is repeated. If all column head units are communicating normally, the positive-to-ground resistance is switched on, with a delay of T, and the positive and negative busbar-to-ground voltages and branch leakage current sensor values ​​are sampled and recorded. The positive and negative busbar-to-ground voltage values ​​after the first switch are sent to the column head units. If not all column head units respond normally, the values ​​are resent. If all column head units respond normally, the negative-to-ground resistance is switched on, with a delay of T, and the positive and negative busbar-to-ground voltages and branch leakage current sensor values ​​are sampled and recorded. If not all column head units respond normally, the values ​​are resent. If all column head units respond normally, the HVDC and the column head units calculate the insulation resistance of each branch based on the voltage and leakage current values. The HVDC receives the branch insulation information uploaded by the column head units. If not all column head units have uploaded the information to the HVDC, the information is received again. If all cabinet head units have been uploaded to HVDC, then HVDC will summarize the insulation information and report it.

[0152] Both coordinated detection mechanisms can locate insulation faults in DC bus outputs from multiple branches.

[0153] The first coordinated detection method requires coordinating and calculating the switching resistor operation of each insulation monitoring unit. Its polling detection time is relatively long, and there is a possibility of conflict in the switching of ground insulation resistance after multiple insulation units have communication failures.

[0154] The second coordinated detection method only requires switching the resistor twice, which can greatly shorten the detection time, save hardware costs, and solve the problem of conflicting switching of insulation resistance to ground after communication abnormalities of multiple insulation units.

[0155] Because the DC busbar has a large capacitance to ground, running from the high-voltage DC switchgear to the head switchgear and then to the downstream load, the voltage value stabilizes relatively slowly during the switching of the ground insulation resistance due to the capacitive effect. Therefore, sampling the voltage value immediately after the ground insulation resistance switch will be inaccurate. A delay is required, set to T. After the ground insulation resistance switch, the busbar-to-ground voltage value is sampled again after a delay of T. This delay value T is typically several seconds to tens of seconds and can be flexibly set according to the actual site conditions.

[0156] Optionally, for scenarios where multiple branches of a high-voltage DC bus output through multiple branches via a cabinet head, one solution to locate the branch with insulation faults is to use a built-in signal generator to inject a low-frequency AC signal into the DC bus, and then use sensors on each branch to detect the signal, thereby locating the branch with insulation abnormalities.

[0157] It should be noted that the master-slave insulation detection unit in this embodiment can be a separate insulation detection unit or integrated into the comprehensive monitoring module of the high-voltage DC power supply and the switchgear. The communication method between them is not limited to CAN, Ethernet, RS485, or even wireless communication. The detection method described in this embodiment only introduces the unbalanced bridge method; a balanced bridge can also be added, or a combination of balanced and unbalanced bridges can be used. The most important feature of this embodiment is that the coordinated detection mechanism greatly improves detection efficiency and does not require the injection of AC signals into the DC bus, resulting in less interference to the system's DC bus. This system can quickly locate faulty branches with abnormal insulation to ground, facilitating rapid on-site maintenance and timely troubleshooting of bus insulation problems.

[0158] In some embodiments, an insulation fault detection method is also provided, applied to the main insulation monitoring unit of an insulation fault detection system as described in any of the above embodiments, such as... Figure 12 As shown, the method includes:

[0159] S1201, obtain the bus voltage to ground under different switching resistors, the first leakage current of the first DC branch, and the second current of the second DC branch.

[0160] Among them, the voltage to ground under different switching resistors refers to the positive and negative busbar voltage values ​​measured by controlling the first and second switches built into the main insulation monitoring unit under two different states (the first state, the first switching resistor is connected to the positive busbar to ground circuit; the second state, the second switching resistor is connected to the negative busbar to ground circuit). Specifically, it includes the first switching voltage to ground U1, the second switching voltage to ground U2, the third switching voltage to ground U3, and the fourth switching voltage to ground U4.

[0161] The first leakage current refers to the leakage current flowing through the first DC branch (the main line from the main insulation monitoring unit to the secondary insulation monitoring unit), which is measured under two switching states and denoted as the first current I1 and the second current I2.

[0162] The second leakage current refers to the leakage current flowing through the second DC branch (the branch line from the insulation monitoring unit to the server load), which is measured under the two switching states respectively. For the kth branch, it is denoted as the third current I1_branch_k and the fourth current I2_branch_k.

[0163] In this embodiment, when the main insulation monitoring unit performs insulation detection, it controls the switch actions according to a preset timing sequence and simultaneously triggers data acquisition. First, it controls the first switch to close and the second switch to open. After a delay and waiting for the system voltage to stabilize, it simultaneously acquires and records: the positive busbar-to-ground voltage U1, the negative busbar-to-ground voltage U2, and the leakage current I1 of the first DC branch. It also receives or directly acquires the leakage current I1_branch_k of each of its respective second DC branches reported by the insulation monitoring unit via the communication network. Subsequently, it controls the first switch to open and the second switch to close. After another delay, it simultaneously acquires and records: the positive busbar-to-ground voltage U3, the negative busbar-to-ground voltage U4, the leakage current I2 of the first DC branch, and the leakage current I2_branch_k of each of the second DC branches. Thus, the main insulation monitoring unit obtains all the raw electrical quantity data required for full-line insulation status analysis.

[0164] S1202 performs fault detection on the line between the main insulation monitoring unit, the slave insulation monitoring unit, and the server load based on the ground voltage, the first leakage current, and the second leakage current, and obtains the first detection result.

[0165] Fault detection refers to the process of calculating the positive-to-ground insulation resistance and negative-to-ground insulation resistance of different sections of the system (main line, first DC branch, and each second DC branch) based on collected electrical quantity data, using circuit models and mathematical formulas, and comparing and analyzing them with preset thresholds.

[0166] The first test result is a comprehensive diagnostic report, which includes at least: the insulation status of the main line (normal / abnormal and resistance value), the insulation status of the first DC branch, the insulation status of each second DC branch, and may further include fault location information (such as the specific fault branch number) and severity assessment.

[0167] In this embodiment, after obtaining the raw data, the main insulation monitoring unit does not directly use it for global resistance calculation, but instead divides it into different logical levels for independent analysis. Through hierarchical calculation, a progressively detailed diagnosis from system overview to specific branches can be achieved. Based on the collected voltages U1-U4 and leakage current data of each path, the main insulation monitoring unit first calculates the positive and negative insulation resistance values ​​to ground for each level, and then compares them one by one with the preset safety thresholds for the corresponding level (these thresholds can be set according to line type, voltage level, and application scenario). If the positive or negative insulation resistance value to ground of a certain level is lower than its threshold, it is determined that there is an insulation fault in the line section corresponding to that level. Finally, the judgment results of all levels are summarized to form a structured first detection result, such as: the main line insulation is normal, the positive insulation resistance to ground of the first DC branch (main line A) is low and alarm, and the negative insulation resistance to ground of the second DC branch (branch line 5) is faulty, etc.

[0168] Specifically, S1202 includes:

[0169] S12021, based on the first switching ground voltage and the second switching ground voltage in the ground voltage, determine the first equivalent resistance value and the second equivalent resistance value of the main line connected to the main insulation monitoring unit.

[0170] Specifically, based on the first switching-to-ground voltage and the second switching-to-ground voltage in the first switching-to-ground voltage, the first main road relationship is determined (see formula (1) above); based on the third switching-to-ground voltage and the fourth switching-to-ground voltage in the second switching-to-ground voltage, the second main road relationship is determined (see formula (2) above); based on the first main road relationship and the second main road relationship, the first equivalent resistance value (i.e., Rp) and the second equivalent resistance value (i.e., Rn) are determined.

[0171] S12022, based on the first switching voltage to ground, the second switching voltage to ground, and the first leakage current, determine the third and fourth equivalent resistance values ​​of the first DC branch in the first leakage current.

[0172] Specifically, based on the first switching voltage to ground, the second switching voltage to ground, and the first current in the first leakage current, the first branch relationship is determined (see formula (3) above); based on the third switching voltage to ground, the fourth switching voltage to ground, and the second current in the first leakage current, the second branch relationship is determined (see formula (4) above); based on the first branch relationship and the second branch relationship, the third equivalent resistance value (i.e., Rdp) and the fourth equivalent resistance value (i.e., Rdn) are determined.

[0173] S12023, based on the first switching voltage to ground, the second switching voltage to ground, and the second leakage current, determine the fifth equivalent resistance value and the sixth equivalent resistance value of the second DC branch in the second leakage current.

[0174] Specifically, based on the first switching voltage to ground in the first switching voltage to ground, the second switching voltage to ground, and the third current in the second leakage current, the third branch relationship is determined (similar to formula (3)); based on the third switching voltage to ground in the second switching voltage to ground, the fourth switching voltage to ground, and the fourth current in the second leakage current, the fourth branch relationship is determined (similar to formula (4)); based on the third branch relationship and the fourth branch relationship, the fifth equivalent resistance value (i.e., Rddp) and the sixth equivalent resistance value (i.e., Rddn) are determined.

[0175] S12024, fault detection is performed on the main line based on the first equivalent resistance value and the second equivalent resistance value, fault detection is performed on the first DC branch based on the third equivalent resistance value and the fourth equivalent resistance value, and fault detection is performed on the second DC branch based on the fifth equivalent resistance value and the sixth equivalent resistance value, to obtain the first detection result.

[0176] In this embodiment, after the main insulation monitoring unit completes the calculation of all resistance values, it performs judgments hierarchically. For example, it compares the calculated Rp and Rn with the "bus insulation threshold"; it compares Rdp and Rdn with the "main line insulation threshold"; and for each second DC branch, it compares its Rddp and Rddn with the "branch line insulation threshold". If a resistance value is lower than the corresponding threshold, it is determined that there is an insulation fault in the corresponding polarity (positive or negative) of the corresponding line section. The main insulation monitoring unit organizes all judgment results to generate a structured first detection result. This result can be a list or report, clearly listing: the overall insulation status of the system (based on Rp, Rn), the insulation status of each first DC branch, and the insulation status of each second DC branch. For abnormal items, the specific insulation resistance calculation value, threshold, and degree of exceedance can be attached to provide detailed basis for operation and maintenance. After the result is generated, it can be displayed through a human-machine interface, stored in a log, or uploaded to the monitoring center.

[0177] The method described in this application, by hierarchically and classifying the acquired bus voltage and leakage current data of each branch, uses a unified mathematical model to calculate the positive and negative insulation resistance to ground of the entire system, the main line, and each terminal branch, achieving full coverage of insulation fault detection from macro to micro. This method offers high location accuracy, shifting from a general alarm of "system insulation degradation" to a specific main or branch line, even distinguishing between positive and negative faults. The calculation model is unified and efficient, employing essentially the same physical model and formulas for lines at different levels. The software implementation is simple, and computational resources are used efficiently. Ultimately, this method transforms insulation fault detection from a simple "presence or absence" judgment into a quantitative, refined, and localizable comprehensive diagnostic report, significantly improving the operation and maintenance efficiency and safety of high-voltage DC multi-branch power supply systems.

[0178] Based on the same inventive concept, this application also provides an insulation fault detection device for implementing the insulation fault detection method described above. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more insulation fault detection device embodiments provided below can be found in the limitations of the insulation fault detection method described above, and will not be repeated here.

[0179] In some embodiments, an insulation fault detection device is provided, comprising:

[0180] The acquisition module is used to acquire the ground voltage of the bus under different switching resistors, the first leakage current of the first DC branch, and the second current of the second DC branch.

[0181] The detection module is used to perform fault detection on the line between the main insulation monitoring unit, the slave insulation monitoring unit and the server load based on the voltage to ground, the first leakage current and the second leakage current, and obtain the first detection result.

[0182] In some embodiments, the detection module is configured to: determine a first equivalent resistance value and a second equivalent resistance value of the main line connected to the main insulation monitoring unit based on the first switching ground voltage and the second switching ground voltage; determine a third equivalent resistance value and a fourth equivalent resistance value of the first DC branch in the first leakage current based on the first switching ground voltage, the second switching ground voltage, and the first leakage current; determine a fifth equivalent resistance value and a sixth equivalent resistance value of the second DC branch in the second leakage current based on the first switching ground voltage, the second switching ground voltage, and the second leakage current; perform fault detection on the main line based on the first equivalent resistance value and the second equivalent resistance value, perform fault detection on the first DC branch based on the third equivalent resistance value and the fourth equivalent resistance value, and perform fault detection on the second DC branch based on the fifth equivalent resistance value and the sixth equivalent resistance value, thereby obtaining a first detection result.

[0183] In some embodiments, the detection module is specifically used to determine a first main path relationship based on the first switching-to-ground voltage and the second switching-to-ground voltage in the first switching-to-ground voltage; to determine a second main path relationship based on the third switching-to-ground voltage and the fourth switching-to-ground voltage in the second switching-to-ground voltage; and to determine a first equivalent resistance value and a second equivalent resistance value based on the first main path relationship and the second main path relationship.

[0184] In some embodiments, the detection module is further configured to determine a first branch relationship based on the first switching-to-ground voltage, the second switching-to-ground voltage, and the first current in the first leakage current; determine a second branch relationship based on the third switching-to-ground voltage, the fourth switching-to-ground voltage, and the second current in the first leakage current; and determine a third equivalent resistance value and a fourth equivalent resistance value based on the first branch relationship and the second branch relationship.

[0185] In some embodiments, the third calculation unit and the detection module are further specifically configured to determine the third branch relationship based on the first switching-to-ground voltage in the first switching-to-ground voltage, the second switching-to-ground voltage, and the third current in the second leakage current; determine the fourth branch relationship based on the third switching-to-ground voltage in the second switching-to-ground voltage, the fourth switching-to-ground voltage, and the fourth current in the second leakage current; and determine the fifth equivalent resistance value and the sixth equivalent resistance value based on the third branch relationship and the fourth branch relationship.

[0186] Each module in the aforementioned insulation fault detection device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0187] In some embodiments, a processor is provided, including a memory storing a computer program, wherein the processor executes the computer program to implement the steps of the insulation fault detection method of any of the above embodiments.

[0188] In some embodiments, a chip is provided, including the processor described above.

[0189] In some embodiments, a computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the steps of the insulation fault detection method of any of the above embodiments.

[0190] In some embodiments, a computer program product is provided, which includes a computer program that, when executed by a processor, implements the steps of the insulation fault detection method of any of the above embodiments.

[0191] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0192] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. An insulation fault detection system, characterized in that, The system includes: a main insulation monitoring unit, at least one first DC branch, at least one slave insulation monitoring unit, at least one second DC branch, and at least one server load; the main insulation monitoring unit is connected to the slave insulation monitoring unit through the at least one first DC branch; the slave insulation monitoring unit is connected to the server load through the at least one second DC branch; the main insulation monitoring unit, the slave insulation monitoring unit, and the server load are all connected to a bus. The main insulation monitoring unit is used to acquire the ground voltage of the bus under different switching resistors, the first leakage current corresponding to the first DC branch, and the second leakage current corresponding to the second DC branch, and to perform fault detection on the line between the main insulation monitoring unit, the slave insulation monitoring unit and the server load based on the ground voltage, the first leakage current and the second leakage current, and to obtain a first detection result.

2. The system according to claim 1, characterized in that, The main insulation monitoring unit includes a first switching circuit, a second switching circuit, a first voltage sampling module, and a second voltage sampling module; the first switching circuit and the first voltage sampling module are connected in parallel, and one end of the first switching circuit and the first voltage sampling module are connected to the positive bus, while the other end is grounded; the second switching circuit and the second voltage sampling module are connected in parallel, and one end of the second switching circuit and the second voltage sampling module are connected to the negative bus, while the other end is grounded; The first voltage sampling module is used to collect the first voltage to ground of the positive busbar when the first switching circuit and the second switching circuit are under different switching resistors; The second voltage sampling module is used to collect the second voltage to ground of the negative bus when the first switching circuit and the second switching circuit are at different switching resistors.

3. The system according to claim 2, characterized in that, The first switching circuit includes a first switching resistor and a first switch, and the second switching circuit includes a second switching resistor and a second switch; the first switching resistor is connected in series with the first switch; the second switching resistor is connected in series with the second switch. The first voltage sampling module is used to collect the first switching voltage to ground of the positive bus when the first switch is controlled to be closed and the second switch is controlled to be open; and to collect the third switching voltage to ground of the positive bus when the first switch is controlled to be open and the second switch is controlled to be closed. The second voltage sampling module is used to collect the second switching-to-ground voltage of the negative bus when the first switch is controlled to be closed and the second switch is controlled to be open; and to collect the fourth switching-to-ground voltage of the negative bus when the first switch is controlled to be open and the second switch is controlled to be closed.

4. The system according to claim 3, characterized in that, The main insulation monitoring unit further includes a control module; the control module is connected to the first switch and the second switch. The control module is used to control the first switch to be in a closed or open state when the first switching voltage to ground is collected, and to control the second switch to be in a closed or open state when the second switching voltage to ground is collected.

5. The system according to any one of claims 1-4, characterized in that, The first DC branch includes a first connecting line and a first leakage current sensor, and the second DC branch includes a second connecting line and a second leakage current sensor; the first leakage current sensor is disposed on the first connecting line, and the first connecting line is connected to the bus; the second leakage current sensor is disposed on the second connecting line, and the second connecting line is connected to the bus.

6. The system according to any one of claims 1-4, characterized in that, The at least one first DC branch includes a main first DC branch and a backup first DC branch; the at least one second DC branch includes a main second DC branch and a backup second DC branch.

7. The system according to any one of claims 1-4, characterized in that, The main insulation monitoring unit and the slave insulation monitoring unit are connected by wired or wireless communication. The main insulation monitoring unit is also used to send the bus voltage to ground under different switching resistors to the slave insulation monitoring unit; The slave insulation monitoring unit is used to acquire the first leakage current of the first DC branch and the second leakage current of the second DC branch, and to perform fault detection on the line between the slave insulation monitoring unit and the server load based on the ground voltage, the first leakage current and the second leakage current, to obtain a second detection result.

8. A method for detecting insulation faults, characterized in that, The method, applied to the main insulation monitoring unit in the insulation fault detection system as described in any one of claims 1-7, comprises: Obtain the bus voltage to ground under different switching resistors, the first leakage current of the first DC branch, and the second leakage current of the second DC branch; Based on the ground voltage, the first leakage current, and the second leakage current, fault detection is performed on the lines between the main insulation monitoring unit, the slave insulation monitoring unit, and the server load to obtain a first detection result.

9. The method according to claim 8, characterized in that, The method of performing fault detection on the line between the main insulation monitoring unit, the slave insulation monitoring unit, and the server load based on the ground voltage, the first leakage current, and the second leakage current to obtain a first detection result includes: Based on the first switched ground voltage and the second switched ground voltage in the ground voltage, determine the first equivalent resistance value and the second equivalent resistance value of the main line connected to the main insulation monitoring unit; Based on the first switching voltage to ground, the second switching voltage to ground, and the first leakage current, determine the third and fourth equivalent resistance values ​​of the first DC branch at the first leakage current. Based on the first switching voltage to ground, the second switching voltage to ground, and the second leakage current, determine the fifth and sixth equivalent resistance values ​​of the second DC branch in the second leakage current. The first detection result is obtained by performing fault detection on the main line based on the first equivalent resistance value and the second equivalent resistance value, fault detection on the first DC branch based on the third equivalent resistance value and the fourth equivalent resistance value, and fault detection on the second DC branch based on the fifth equivalent resistance value and the sixth equivalent resistance value.

10. The method according to claim 9, characterized in that, The step of determining the first equivalent resistance value and the second equivalent resistance value of the main line connected to the main insulation monitoring unit based on the first switched ground voltage and the second switched ground voltage in the ground voltage includes: The first main road relationship is determined based on the first switching-to-ground voltage and the second switching-to-ground voltage in the first switching-to-ground voltage. The second main road relationship is determined based on the third and fourth switching-to-ground voltages in the second switching-to-ground voltage. The first equivalent resistance value and the second equivalent resistance value are determined based on the first main path relationship and the second main path relationship.

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