Insulation online monitoring system and method for direct current power supply system

Abstract

The invention provides an insulation on-line monitoring system and method of a direct current power supply system, and solves the technical problem that the existing monitoring means is not suitable for the direct current power supply system. The system comprises a bridge type insulation detector used for timely detecting the insulation resistance value of the high-voltage DC bus and feeding back the insulation resistance value; the leakage current sensor is used for detecting the insulation resistance value of the high-voltage direct-current branch in real time and feeding back the insulation resistance value; and the injection type insulation detector is used for detecting the insulation resistance value of the low-voltage direct-current bus in real time and feeding back the insulation resistance value. An appropriate direct-current power supply system insulation on-line monitoring method is designed through analysis from the aspects of electrical architecture, voltage class, insulation abnormity rapid positioning and the like of the direct-current power supply system, the insulation problem is rapidly positioned, and a high-precision insulation monitoring scheme is achieved. Insulation abnormal conditions of various levels of electrical systems can be found in time, and the safety of personnel and electrical equipment is fully guaranteed.

Description

Technical Field

[0001] This invention relates to the field of power supply technology, and more specifically to an online insulation monitoring system and method for DC power supply systems. Background Technology

[0002] In existing technologies, with the advancement of power electronics technology, the advantages of DC power supply systems—high efficiency and fewer intermediate links—are gradually becoming apparent. DC microgrid systems contain two voltage levels of DC power supply lines: 600V high-voltage DC and 28V low-voltage DC, and typically include hundreds of load devices. Insulation problems can affect the safety of personnel and equipment. Therefore, effectively monitoring the insulation status of DC buses and branches at different voltage levels, and quickly locating faults when potential insulation problems occur, is crucial for ensuring personnel safety and the normal operation of electrical equipment. Summary of the Invention

[0003] In view of the above problems, embodiments of the present invention provide an online insulation monitoring system and method for DC power supply systems, solving the technical problem that existing monitoring methods are not suitable for DC power supply systems.

[0004] The insulation online monitoring system for a DC power supply system according to an embodiment of the present invention includes:

[0005] A bridge-type insulation tester is used to detect and feedback the insulation resistance value of high-voltage DC busbars in real time.

[0006] Leakage current sensor is used to detect and feedback the insulation resistance value of high voltage DC branch in real time;

[0007] An injection-type insulation tester is used to detect and provide feedback on the insulation resistance value of low-voltage DC bus in real time.

[0008] In one embodiment of the present invention, the high-voltage DC bus includes a single high-voltage DC bus and a redundant backup high-voltage DC bus, the high-voltage DC branch includes a high-voltage line connecting the high-voltage load, the high-voltage input of the DC / DC converter and the energy storage unit, and the low-voltage DC bus includes a low-voltage line of the low-voltage output of the DC / DC converter.

[0009] In one embodiment of the present invention, the DC power supply system includes:

[0010] High-voltage DC busbars are used to draw power from the main power supply network to form local high-voltage DC circuits;

[0011] A DC / DC converter is used to convert a high-voltage DC input into a low-voltage DC output.

[0012] The low-voltage DC bus is used to connect DC / DC converters to form local low-voltage DC circuits.

[0013] In one embodiment of the present invention, an extended topology of low-voltage DC buses with different voltage levels can be formed by combining a plurality of such DC / DC converters. This includes forming parallel low-voltage DC buses by using DC / DC converters at the same level, and forming low-voltage DC buses with decreasing voltage levels by using DC / DC converters at progressive levels.

[0014] In one embodiment of the present invention, an energy storage unit is connected in parallel near the load location on the high-voltage DC bus and / or the low-voltage DC bus.

[0015] In one embodiment of the present invention, two high-voltage DC buses are provided, which are respectively connected to the main power supply network line, and the two high-voltage DC buses are connected by a tie switch.

[0016] The online insulation monitoring method for a DC power supply system according to an embodiment of the present invention includes:

[0017] During the operation of the DC power supply system, each insulation detection device is periodically initialized to form a real-time detection process.

[0018] The feedback data from each testing device is synchronized and stored in a real-time manner.

[0019] Based on the alarm strategy, threshold and trend judgments are performed on the timing feedback data, and alarm data and circuit operation data are generated based on the judgment results.

[0020] In one embodiment of the present invention, the step of performing threshold judgment and trend judgment on time-series feedback data according to the alarm strategy includes:

[0021] Determine whether a clear leakage current alarm data is generated based on the jump threshold of the insulation resistance value at the same location.

[0022] Determine whether leakage current trend alarm data is formed based on the time-series changes in the insulation resistance value at the same location.

[0023] Determine whether aging alarm data for related connecting cables or downstream cables is generated based on the temporal changes in insulation resistance values ​​at various locations within the same local area.

[0024] Determine whether aging alarm data for related connecting cables or upstream cables is generated based on the temporal changes in insulation resistance values ​​at various locations within adjacent areas.

[0025] Determine whether aging alarm data for the busbar is generated based on the temporal changes in the insulation resistance values ​​at various locations within the same discrete local area.

[0026] The insulation online monitoring system for a DC power supply system according to an embodiment of the present invention includes:

[0027] The memory is used to store the program code in the above-mentioned online insulation monitoring method.

[0028] A processor for executing the program code.

[0029] The insulation online monitoring system for a DC power supply system according to an embodiment of the present invention includes:

[0030] The detection synchronization device is used to periodically initialize each insulation detection device during the operation of the DC power supply system, forming a real-time detection process;

[0031] A data synchronization device is used to synchronize and store the feedback data from various testing devices in a timely manner.

[0032] The status response device is used to perform threshold and trend judgment on timing feedback data according to the alarm strategy, and generate alarm data and circuit operation data based on the judgment results.

[0033] This invention relates to an online insulation monitoring system and method for DC power supply systems. It analyzes the electrical architecture, voltage level, and rapid location of insulation anomalies in DC power supply systems, designs a suitable online insulation monitoring method for DC power supply systems, rapidly locates insulation problems, and achieves a high-precision insulation monitoring solution. This allows for the timely detection of insulation anomalies at various levels of the electrical system, fully ensuring the safety of personnel and electrical equipment. Attached Figure Description

[0034] Figure 1 The diagram shown is a schematic diagram of the architecture of an online insulation monitoring system for a DC power supply system according to an embodiment of the present invention.

[0035] Figure 2 The diagram shown is a schematic flowchart of an online insulation monitoring method for a DC power supply system according to an embodiment of the present invention.

[0036] Figure 3 The diagram shown is a schematic diagram of the architecture of an online insulation monitoring system for a DC power supply system according to an embodiment of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer and more understandable, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0038] An embodiment of the present invention provides an online insulation monitoring system for a DC power supply system, such as... Figure 1 As shown. In Figure 1 In this embodiment, the DC power supply system includes:

[0039] A high-voltage DC bus is used to draw power from the main power supply network to form a local high-voltage DC circuit.

[0040] A DC / DC converter is used to convert a high-voltage DC input into a low-voltage DC output.

[0041] The low-voltage DC bus is used to connect DC / DC converters to form local low-voltage DC circuits.

[0042] like Figure 1 As shown, in one embodiment of the present invention, the high-voltage DC bus adopts a 600V high-voltage rating, and the low-voltage DC bus adopts a 28V low-voltage rating.

[0043] like Figure 1 As shown, in one embodiment of the invention, a high-voltage load is connected via a branch of a high-voltage DC bus. An independent low-voltage DC bus is formed on this branch via a DC / DC converter, and the low-voltage load is connected via the low-voltage DC bus. In another embodiment, an extended topology of low-voltage DC buses with different voltage levels can be formed by combining several DC / DC converters. For example, parallel low-voltage DC buses can be formed using DC / DC converters at the same level, and the voltage levels of the low-voltage DC buses can be the same or different. Alternatively, a series of DC / DC converters at progressively higher levels can form low-voltage DC buses with decreasing voltage levels.

[0044] like Figure 1 As shown, in one embodiment of the present invention, an energy storage unit is connected in parallel near the load location on the high-voltage DC bus and / or the low-voltage DC bus to reduce line transmission losses, meet the power demand of high-power pulse loads in the system, and compensate for transient voltage drops. In one embodiment of the present invention, the energy storage unit is a lead-acid battery.

[0045] In one embodiment of the present invention, two high-voltage direct current (HVDC) buses are provided, each connected to the main power supply network line. The two HVDC buses are connected by a tie switch, forming a dual-circuit redundant design that is independent of each other and serves as backup for one another. This ensures reliable power supply switching under conditions such as single bus failure or single high-voltage cable failure, thus improving the reliability of power supply.

[0046] In one embodiment of the present invention, the energy storage unit is connected in parallel with two high-voltage DC buses.

[0047] like Figure 1 As shown, in one embodiment of the present invention, it includes:

[0048] The bridge-type insulation tester (monitor) is used to detect and provide feedback on the insulation resistance value of high-voltage DC busbars in a timely manner.

[0049] This method is used at single high-voltage DC bus, redundant backup, or standby high-voltage DC bus to test the insulation of the entire high-voltage DC system. By monitoring the voltage to ground of the positive and negative buses, it can quickly issue an alarm when an insulation problem occurs.

[0050] Leakage current sensor is used to detect and provide feedback on the insulation resistance value of high voltage DC branch in real time.

[0051] This technology is used in the high-voltage DC branches that connect the high-voltage load, the high-voltage input of the DC / DC converter, and the energy storage unit. Under normal conditions, the sum of the positive and negative currents of the branch is zero. When there is insulation resistance in the branch, the current sensor can detect subtle changes in current and thus confirm that an insulation fault has occurred in the branch.

[0052] An injection-type insulation tester (monitor) is used to detect and provide feedback on the insulation resistance value of low-voltage DC bus in real time.

[0053] This method is employed at the low-voltage output of DC / DC converters, where specific electrical signals (such as DC, low-frequency AC, or pulse current) are actively injected, and the insulation resistance is calculated based on signal feedback. It is not affected by DC voltage and has higher accuracy and reliability.

[0054] The online insulation monitoring system for DC power supply systems in this invention optimizes the configuration of detection (monitoring) instruments based on the electrical architecture, voltage level, and rapid insulation anomaly location requirements of the DC power supply system. Various types of detection (monitoring) instruments are deployed according to the voltage safety level in the electrical system architecture, enabling state-based detection of voltage insulation anomalies and forming rapid, high-precision insulation monitoring at all levels of the current system. This fully ensures the safety of personnel and electrical equipment.

[0055] An embodiment of the present invention provides an online insulation monitoring method for a DC power supply system, as follows: Figure 2 As shown. In Figure 2 In this embodiment, the following are included:

[0056] Step 100: Periodically initialize each insulation detection device during the operation of the DC power supply system to form a real-time detection process.

[0057] The detection devices in this invention include, but are not limited to, bridge-type insulation detectors (monitors), injection-type insulation detectors (monitors), and leakage current sensors. An online insulation monitoring cycle strategy for each part of the system is formed based on an assessment of the load density, power consumption, and operating environment of the DC microgrid formed by the DC power supply system. For example, the detection cycle length is increased in areas with high load power consumption and high load density (within the complete circuit topology) or within a voltage level range. In one embodiment of this invention, the detection cycle of all types of detection devices is the same, maintaining uninterrupted detection.

[0058] Step 200: Synchronize and store the feedback data from each testing device in a time sequence.

[0059] Feedback data from each testing device is uploaded via wired or wireless communication links established using general communication technologies. The timing synchronization and storage of this feedback data form the basis for judging the insulation performance and status of the DC microgrid environment.

[0060] Step 300: Perform threshold and trend judgments on the timing feedback data according to the alarm strategy, and generate alarm data and circuit operation data based on the judgment results.

[0061] Alarm strategies that assess the overall and local insulation performance of a DC microgrid environment based on time-series feedback insulation resistance data include, but are not limited to:

[0062] Determine whether a clear leakage current alarm data is generated based on the jump threshold of the insulation resistance value at the same location.

[0063] Determine whether leakage current trend alarm data is formed based on the time-series changes in the insulation resistance value at the same location.

[0064] Determine whether aging alarm data for related connecting cables or downstream cables is generated based on the temporal changes in insulation resistance values ​​at various locations within the same local area.

[0065] Determine whether aging alarm data for related connecting cables or upstream cables is generated based on the temporal changes in insulation resistance values ​​at various locations within adjacent areas.

[0066] Determine whether aging alarm data for the busbar is generated based on the temporal changes in the insulation resistance values ​​at various locations within the same discrete local area.

[0067] In one embodiment of the present invention, for a dual high-voltage DC bus, the following is included:

[0068] The switching of the current high-voltage DC bus and the redundant high-voltage DC bus is controlled by the degree of change in the insulation resistance value of the high-voltage DC bus.

[0069] In one embodiment of the present invention, for a dual high-voltage DC bus, the following is included:

[0070] When the current high-voltage DC bus is cut off and the redundant high-voltage DC bus is cut in, the synchronous energy storage unit balances the partial discharge power to overcome the instantaneous power outage.

[0071] In one embodiment of the present invention, a low-voltage DC bus includes:

[0072] When a local branch circuit of the low-voltage DC bus is shut off due to leakage, the synchronous energy storage unit balances the local charging power to overcome the instantaneous voltage rise.

[0073] An embodiment of the present invention provides an online insulation monitoring system for a DC power supply system, comprising:

[0074] A memory is used to store program code during the processing of the online insulation monitoring method described in the above embodiments;

[0075] The processor is used to execute program code in the online insulation monitoring method of the above embodiments.

[0076] The processor can be a DSP (Digital Signal Processor), an FPGA (Field-Programmable Gate Array), an MCU (Microcontroller Unit) system board, a SoC (System on a Chip) system board, or a PLC (Programmable Logic Controller) minimum system including I / O.

[0077] An embodiment of the present invention provides an online insulation monitoring system for a DC power supply system, such as... Figure 3 As shown. In Figure 3 In this embodiment, the following are included:

[0078] The detection synchronization device 10 is used to periodically initialize each insulation detection device during the operation of the DC power supply system, forming a real-time detection process.

[0079] Data synchronization device 20 is used to synchronize and store the feedback data from each detection device in a timely manner;

[0080] The status response device 30 is used to perform threshold judgment and trend judgment on timing feedback data according to the alarm strategy, and to generate alarm data and circuit operation data based on the judgment results.

[0081] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An online insulation monitoring system for a DC power supply system, characterized in that, include: A bridge-type insulation tester is used to detect and feedback the insulation resistance value of high-voltage DC busbars in real time. Leakage current sensor is used to detect and feedback the insulation resistance value of high voltage DC branch in real time; An injection-type insulation tester is used to detect and provide feedback on the insulation resistance value of low-voltage DC bus in real time.

2. The online insulation monitoring system for a DC power supply system as described in claim 1, characterized in that, The high-voltage DC bus includes a single high-voltage DC bus and a redundant backup high-voltage DC bus. The high-voltage DC branch includes high-voltage lines connecting the high-voltage load, the high-voltage input of the DC / DC converter, and the energy storage unit. The low-voltage DC bus includes low-voltage lines of the low-voltage output of the DC / DC converter.

3. The online insulation monitoring system for a DC power supply system as described in claim 2, characterized in that, The DC power supply system includes: High-voltage DC busbars are used to draw power from the main power supply network to form local high-voltage DC circuits; A DC / DC converter is used to convert a high-voltage DC input into a low-voltage DC output. The low-voltage DC bus is used to connect DC / DC converters to form local low-voltage DC circuits.

4. The online insulation monitoring system for a DC power supply system as described in claim 3, characterized in that, By combining several of the aforementioned DC / DC converters, extended topologies of low-voltage DC buses with different voltage levels can be formed. This includes forming parallel low-voltage DC buses by using DC / DC converters at the same level, and forming low-voltage DC buses with decreasing voltage levels by using DC / DC converters at progressive levels.

5. The online insulation monitoring system for a DC power supply system as described in claim 3, characterized in that, An energy storage unit is connected in parallel near the load location on the high-voltage DC bus and / or the low-voltage DC bus.

6. The online insulation monitoring system for a DC power supply system as described in claim 3, characterized in that, Two high-voltage DC buses are installed, each connected to the main power supply network line, and the two high-voltage DC buses are connected by a tie switch.

7. A method for online insulation monitoring of a DC power supply system, characterized in that, include: During the operation of the DC power supply system, each insulation detection device is periodically initialized to form a real-time detection process. The feedback data from each testing device is synchronized and stored in a real-time manner. Based on the alarm strategy, threshold and trend judgments are performed on the timing feedback data, and alarm data and circuit operation data are generated based on the judgment results.

8. The online insulation monitoring method for a DC power supply system as described in claim 7, characterized in that, The step of performing threshold and trend judgment on time-series feedback data according to the alarm strategy includes: Determine whether a clear leakage current alarm data is generated based on the jump threshold of the insulation resistance value at the same location. Determine whether leakage current trend alarm data is formed based on the time-series changes in the insulation resistance value at the same location. Determine whether aging alarm data for related connecting cables or downstream cables is generated based on the temporal changes in insulation resistance values ​​at various locations within the same local area. Determine whether aging alarm data for related connecting cables or upstream cables is generated based on the temporal changes in insulation resistance values ​​at various locations within adjacent areas. Determine whether aging alarm data for the busbar is generated based on the temporal changes in the insulation resistance values ​​at various locations within the same discrete local area.

9. An online insulation monitoring system for a DC power supply system, characterized in that, include: A memory for storing program code during the process of the online insulation monitoring method as described in any one of claims 7 to 8; A processor for executing the program code.

10. An online insulation monitoring system for a DC power supply system, characterized in that, include: The detection synchronization device is used to periodically initialize each insulation detection device during the operation of the DC power supply system, forming a real-time detection process; A data synchronization device is used to synchronize and store the feedback data from various testing devices in a timely manner. The status response device is used to perform threshold and trend judgment on timing feedback data according to the alarm strategy, and generate alarm data and circuit operation data based on the judgment results.

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