Leakage protection system for low-voltage IT power supply system

Abstract

The invention relates to the technical field of electrical safety monitoring, in particular to a leakage protection system for a low-voltage IT power supply system. Comprising an impedance spectrum identification unit used for constructing an original spectrum data set; calculating a system-to-ground complex impedance spectrum based on the original spectrum data set; a parallel RC equivalent circuit model is applied to decouple the real insulation resistance and the system ground capacitance based on the system ground complex impedance spectrum; the dynamic evaluation unit is used for constructing an insulation health index; calculating a system structure change factor; the trend prediction unit is used for calculating an insulation aging rate based on a time sequence formed by historical real insulation resistance data; the comprehensive risk decision-making unit is used for calculating a comprehensive risk index; and outputting a tripping signal in response to the insulation health index exceeding a preset final protection limit value. The problem of false alarm caused by the fact that a traditional protection device cannot distinguish resistive leakage current and capacitive leakage current is solved, and the protection accuracy is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of electrical safety monitoring technology, specifically to a leakage current protection system for low-voltage IT power supply systems. Background Technology

[0002] As low-voltage IT power supply systems are increasingly used in critical fields such as medical care, data centers, and precision manufacturing, the requirements for power supply continuity and security are also increasing. In modern IT systems, the use of a large number of nonlinear loads and frequency converters, as well as the increasingly complex system network topology, has led to a significant increase in the system's capacitance to ground, which poses a severe challenge to traditional insulation monitoring technologies. Currently, conventional leakage current protection devices mainly achieve protection by monitoring the instantaneous value of total leakage current to ground or insulation resistance and comparing it with a fixed threshold. However, this traditional method has its inherent technical limitations. It cannot effectively distinguish between resistive leakage current caused by actual insulation aging or damage and capacitive leakage current generated by inherent cables, filters, etc. in the system. In systems with a large capacitance component, capacitive leakage current may dominate, thus masking the true insulation condition.

[0003] This confusion directly leads to two main problems: First, false alarms, where the system insulation is in good condition, but a large capacitive leakage current causes the total leakage current to exceed the alarm threshold, triggering unnecessary shutdowns for maintenance and affecting the continuity of power supply; Second, leakage alarms, where the insulation has begun to deteriorate slowly, but because its resistive leakage current component has not yet caused a significant change in the total leakage current, the system cannot detect potential risks in time. In addition, alarm mechanisms that rely on a single threshold are reactive and lack the ability to analyze and predict insulation aging trends, making predictive maintenance impossible. Therefore, accurately identifying the true insulation resistance of the system, eliminating the interference of the system's capacitance to ground, and conducting a forward-looking comprehensive risk assessment in conjunction with aging trends to overcome the false alarms and missed alarms of traditional methods has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention discloses a leakage current protection system for low-voltage IT power supply systems. Specifically, the technical solution of this invention is as follows: Leakage protection systems for low-voltage IT power supply systems include: Impedance spectrum identification unit is used to inject a preset composite voltage signal and collect the total leakage current response to ground to construct the original spectrum dataset; based on the original spectrum dataset, the system to ground complex impedance spectrum is calculated; and a parallel RC equivalent circuit model is applied to decouple the real insulation resistance and system to ground capacitance based on the system to ground complex impedance spectrum. The dynamic evaluation unit is used to construct an insulation health index based on the actual insulation resistance and the preset insulation resistance alarm limit; and to calculate the system structure change factor based on the system's capacitance to ground and the preset capacitance reference value. The trend prediction unit is used to calculate the insulation aging rate based on a time series formed from historical real insulation resistance data; The comprehensive risk decision-making unit is used to calculate the comprehensive risk index by combining the insulation health index, system structure change factor and insulation aging rate in a weighted fusion manner; to perform graded early warning based on the comprehensive risk index; and to output a trip signal in response to the insulation health index exceeding the preset final protection limit.

[0005] Preferably, the process by which the impedance spectrum identification unit calculates the complex impedance spectrum of the ground includes: Using the complex Ohm's law, the injection voltage and total ground leakage current response at each frequency point in the original spectrum dataset are calculated to generate complex impedance values ​​including equivalent resistance and equivalent reactance, thus forming the system's complex impedance spectrum to ground.

[0006] Preferably, the process by which the impedance spectrum identification unit decouples the actual insulation resistance and the system-to-ground capacitance includes: The least squares method is used to optimize the model, and the actual insulation resistance and system-to-ground capacitance values ​​are determined by numerical optimization algorithm, so that the sum of squared errors between the theoretical impedance calculated based on the value and the system-to-ground complex impedance spectrum is minimized.

[0007] Preferably, the dynamic evaluation unit calculates the insulation health index by dividing the preset insulation resistance alarm limit by the actual insulation resistance.

[0008] Preferably, the dynamic evaluation unit calculates the difference between the system's capacitance to ground and a preset capacitance reference value, and divides the difference by the capacitance reference value to obtain the system structure change factor.

[0009] Preferably, the dynamic evaluation unit is further used for: When the system structure change factor continues to exceed the preset capacitance fluctuation limit for a preset duration, a prompt is made to update the capacitance reference value. In response to the confirmation command, the capacitance reference value is updated with a new stable capacitance value.

[0010] Preferably, the trend prediction unit processes the actual insulation resistance time series within a preset time window to calculate the relative loss rate of insulation resistance per unit time, thereby obtaining the insulation aging rate.

[0011] Preferably, the process by which the comprehensive risk decision-making unit calculates the comprehensive risk index includes: The comprehensive risk index is obtained by multiplying the insulation health index, the system structure change factor normalized by the preset capacitance fluctuation limit, and the insulation aging rate normalized by the preset aging rate threshold by their respective preset weighting coefficients.

[0012] Preferably, the process of the comprehensive risk decision-making unit executing tiered early warning includes: When the comprehensive risk index is lower than the first warning threshold, it is determined to be in a normal state; When the comprehensive risk index reaches the first warning threshold but is lower than the second warning threshold, a level of attention alert is triggered. When the comprehensive risk index is not lower than the second warning threshold, a warning level alarm is triggered.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention effectively eliminates the interference of capacitive leakage current generated by the system's ground capacitance by accurately decoupling the true insulation resistance, thus solving the problem of false alarms caused by the inability of traditional protection devices to distinguish between resistive and capacitive leakage currents, and significantly improving the accuracy of protection.

[0014] 2. This invention quantifies the insulation aging rate based on historical data of real insulation resistance, enabling forward-looking prediction of insulation performance degradation trends. It transforms the traditional passive response after a fault into proactive early warning, providing a decision-making basis for predictive maintenance.

[0015] 3. This invention integrates information from three dimensions: immediate insulation status, system structural stability, and future aging trends, forming a comprehensive risk assessment index. This overcomes the one-sidedness of relying on a single fixed threshold for judgment, making risk assessment more comprehensive and three-dimensional, and decision-making more reliable.

[0016] 4. This invention establishes a control strategy that combines graded early warning with final trip protection, which can trigger different levels of response according to the severity of the risk. This provides clear operational guidance for maintenance personnel and ensures absolute safety in the event of extreme deterioration, thereby comprehensively improving the safety, continuity and operation and maintenance efficiency of the power supply system. Attached Figure Description

[0017] The present invention will be further explained below with reference to the accompanying drawings and embodiments: Figure 1 This is a flowchart of the system of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0019] Example 1: Please see Figure 1 Leakage protection systems for low-voltage IT power supply systems include: Impedance spectrum identification unit is used to inject a preset composite voltage signal and collect the total leakage current response to ground to construct the original spectrum dataset; based on the original spectrum dataset, the system to ground complex impedance spectrum is calculated; and a parallel RC equivalent circuit model is applied to decouple the real insulation resistance and system to ground capacitance based on the system to ground complex impedance spectrum. The dynamic evaluation unit is used to construct an insulation health index based on the actual insulation resistance and the preset insulation resistance alarm limit; and to calculate the system structure change factor based on the system's capacitance to ground and the preset capacitance reference value. The trend prediction unit is used to calculate the insulation aging rate based on a time series formed from historical real insulation resistance data; The comprehensive risk decision-making unit is used to calculate the comprehensive risk index by weighted fusion of insulation health index, system structure change factor and insulation aging rate; to perform graded early warning based on comprehensive risk index; and to output trip signal in response to insulation health index exceeding preset final protection limit. This embodiment discloses a leakage current protection system for low-voltage IT power supply systems. The system aims to overcome the false alarm and missed alarm problems caused by traditional leakage current protection devices that rely solely on a single leakage current threshold. Through multi-dimensional dynamic evaluation and trend prediction, it achieves accurate and forward-looking management of insulation risks. The system includes: an impedance spectrum identification unit, a dynamic evaluation unit, a trend prediction unit, and a comprehensive risk decision-making unit; these four units work together to form a complete technical closed loop from data acquisition, state identification, risk assessment to decision control; The impedance spectrum identification unit aims to accurately acquire two core parameters that characterize the physical state of a system: true insulation resistance. and system-to-ground capacitance This provides a high-quality data foundation for all subsequent assessments and predictions; In this embodiment, the unit performs broadband excitation signal injection and response acquisition. Specifically, it actively injects a preset composite voltage signal containing multiple discrete frequency points, such as 20 characteristic frequency points selected from the range of 50Hz to 5000Hz, between the three-phase conductors of the system and the protective ground. The amplitude of this signal is controlled within a safe range to avoid interfering with the normal operation of the system. Simultaneously, a high-precision synchronous acquisition module captures the signal at each discrete frequency point in real time and synchronously. Injected excitation voltage phasor And the total ground leakage current response phasor generated by the system as a result The collected data is for Together they constitute the original spectrum dataset; Based on the above dataset, this unit calculates the system's complex impedance spectrum to ground. This step aims to transform the original voltage and current data into impedance information that better reveals the system's intrinsic physical characteristics. Finally, this unit applies a parallel RC equivalent circuit model to decouple the actual insulation resistance from the frequency-dependent complex impedance spectrum. and system-to-ground capacitance The ground characteristics of an IT power supply system can be precisely equivalent to a real insulation resistance. With a system to ground capacitance A parallel model; in which, The resistance value does not change with frequency, representing the true insulation level; while The capacitive reactance is inversely proportional to the frequency, and becomes the main path for leakage current in the high-frequency range; the purpose of this step is to extract the true insulation level from the mixed total leakage current. Separate to exclude The resulting capacitive leakage current interference; The purpose of the dynamic evaluation unit is to conduct a standardized, multi-dimensional assessment of the current health status of the system from two dimensions: immediate insulation status and system structural stability. This unit is based on the actual insulation resistance decoupled from the impedance spectrum identification unit. With a preset insulation resistance alarm limit To construct an insulation health index Among them, the insulation resistance alarm limit It is a legally mandated safety threshold set according to industry safety standards, and it is the authoritative benchmark for judging whether insulation has failed; Furthermore, this unit is also based on the system's capacitance to ground. With a preset capacitance reference value Calculate the system structure change factor Among them, the capacitor reference value This refers to the system undergoing multiple measurements after initial debugging or in a confirmed stable operating state. The obtained statistical average represents the healthy topology of the system; The calculation aims to quantify the degree of deviation of the current system topology from this health benchmark, which may be caused by factors such as cable dampness, the addition or removal of high-power equipment; The trend prediction unit aims to shift from post-event alarms to pre-event warnings by analyzing historical data to quantify the deterioration trend of insulation performance. This unit periodically stores the actual insulation resistance calculated by the impedance spectrum identification unit. The data is then arranged chronologically to form a time-series dataset; based on this historical data sequence, the unit calculates the insulation aging rate. ;this The value does not reflect Instead of observing instantaneous changes, it analyzes data over a time window to quantify the relative downward trend of insulation resistance, thereby enabling the prediction of future insulation conditions. The technical purpose of the integrated risk decision-making unit is to conduct a final summary analysis of all the aforementioned assessment and prediction results, and output clear and hierarchical control instructions accordingly. This unit will include the insulation health index. This represents immediate risk and factors affecting system structure changes. This represents structural stability and insulation aging rate. These represent future risks and are weighted and aggregated to calculate a comprehensive risk index. This fusion computing aims to avoid the limitations of any single indicator and provide a comprehensive and multi-dimensional assessment of the system's health. This unit is based on a comprehensive risk index. Implement tiered early warning systems; different early warning thresholds are set within each unit, based on... The range in which the system is located triggers different levels of response, thereby providing operations and maintenance personnel with clear operational guidelines that are in line with the current risk level. In addition, the system has a built-in set of highest-priority safety protection logic; each unit independently monitors the insulation health index. And in response to the insulation health index Exceeding a preset final protection limit When this occurs, a trip signal is directly output; among which, the final protection limit is... The critical risk coefficient is set based on engineering practice, and its value is usually between 1.5 and 2.0. This design ensures that in the critical moment when the system insulation deteriorates to an extreme degree and is about to break down, the power supply can be forcibly cut off as quickly as possible, bypassing the comprehensive assessment, so as to protect the safety of personnel and equipment. The leakage current protection system in this embodiment, through the coordinated operation of the above four units, achieves in-depth identification and proactive management of the insulation status of low-voltage IT systems; the system identifies core physical parameters. and The system comprehensively evaluates and predicts from three dimensions: immediate status, structural stability, and aging trend. The benefits are: it improves the accuracy of leakage protection and effectively avoids false alarms caused by capacitive leakage current; at the same time, it enables predictive maintenance through trend prediction, transforming passive response into proactive management, and improving the safety, continuity, and operation and maintenance efficiency of the power supply system.

[0020] Example 2: The process of calculating the complex impedance spectrum of the system to ground by the impedance spectrum identification unit includes: Using the complex Ohm's law, the injection voltage and total ground leakage current response at each frequency point in the original spectrum dataset are calculated to generate complex impedance values ​​including equivalent resistance and equivalent reactance, forming the system's complex impedance spectrum to ground. This embodiment, based on Embodiment 1, clarifies the process by which the impedance spectrum identification unit calculates the complex impedance spectrum of the ground. In this process, the impedance spectrum identification unit employs complex Ohm's law; for each discrete frequency point in the original spectrum dataset... The unit injects the voltage phasor at this point. Divide by the measured total ground leakage current response phasor The calculation formula is as follows: ; In this relation For frequency; and The original input to the model consists of the acquired voltage and current phasors; the calculated output is... For a complex number, the actual part The imaginary part represents the system's equivalent resistance at that frequency. This represents the system's equivalent reactance at that frequency; where, The imaginary unit is used; by performing this calculation on all the frequency points collected one by one, a series of complex impedance values ​​are finally generated, which together constitute the system-to-ground complex impedance spectrum that describes the system impedance as a function of frequency.

[0021] Example 3: The process by which the impedance spectrum identification unit decouples the actual insulation resistance and system-to-ground capacitance includes: The least squares method is used to optimize the model, and the actual insulation resistance and system-to-ground capacitance values ​​are determined by numerical optimization algorithm, so that the sum of squared errors between the theoretical impedance calculated based on the value and the system-to-ground complex impedance spectrum is minimized. This embodiment further defines the actual insulation resistance decoupled from the impedance spectrum identification unit in Embodiment 1. and system-to-ground capacitance Specific technical means; In this embodiment, the decoupling process employs a least squares optimization model; the goal of this model is to find an optimal set of... and The values ​​are such that the theoretical impedance calculated based on these values ​​and the parallel RC equivalent circuit model is consistent with the system-to-ground complex impedance spectrum generated by the actual measurement in the previous step. Minimize the error between them; the optimization objective function is: ; in, This refers to the complex impedance value in the actual measured system-to-ground complex impedance spectrum, while This is the theoretical complex impedance calculated based on a parallel RC equivalent circuit model; the goal of this function is to find an optimal set of actual insulation resistances. and system-to-ground capacitance This makes it possible to measure frequencies at all frequency points. The sum of squares of the errors between the theoretical impedance and the actual measured impedance is minimized; in, The theoretical complex impedance of the parallel RC equivalent circuit model is expressed as: ; The input to this function is the series of complex impedance values ​​calculated in the previous step. The system uses numerical optimization algorithms, such as the Levenberg-Marquardt algorithm, to iteratively solve for the function that minimizes the sum of squared errors. and To improve solution accuracy, higher weights can be assigned to errors in low-frequency data points during numerical implementation. The technical reason for this is... The contribution is more significant in the low-frequency region; although for systems with extremely complex structures, their ground characteristics may contain higher-order impedance components, the parallel RC model has been proven to capture the core parameters most critical to insulation risk assessment with sufficient accuracy, achieving a good balance between universality and accuracy in engineering applications.

[0022] Example 4: The dynamic evaluation unit calculates the insulation health index by dividing the preset insulation resistance alarm limit by the actual insulation resistance. This embodiment illustrates how the dynamic evaluation unit in Embodiment 1 calculates the insulation health index. Specific methods; The dynamic evaluation unit uses preset insulation resistance alarm limits. Divide by the actual insulation resistance obtained from real-time decoupling. The insulation health index was calculated. The calculation formula is as follows: ; In this formula, the input is the result calculated from the previous steps. , As a preset constant reference; output It is a dimensionless relative risk index; when the system insulation is good, Much larger ,at this time Much less than 1; when the system insulation deteriorates, The value decreased and approached hour, The value approaches 1; once Below the legal limit , A value greater than 1 clearly indicates that the system has entered a risky state.

[0023] Example 5: The dynamic evaluation unit calculates the difference between the system's capacitance to ground and the preset capacitance reference value, and divides the difference by the capacitance reference value to obtain the system structure change factor. The dynamic evaluation unit is also used for: When the system structure change factor continues to exceed the preset capacitance fluctuation limit for a preset duration, the system prompts for an update of the capacitance reference value, and in response to the confirmation command, updates the capacitance reference value with a new stable capacitance value. This embodiment describes the evaluation mechanism of the dynamic evaluation unit for changes in system structure. This mechanism can not only detect changes, but also has adaptive update capabilities. Based on the limitations of Embodiment 5, the dynamic evaluation unit calculates the current system's capacitance to ground. Compared with the preset capacitance reference value The difference is then divided by the capacitor reference value. The system structure change factor is obtained. The calculation formula is as follows: ; Before calculation, the system will verify the capacitance reference value. To check if it is a non-zero valid value to avoid calculation errors; a valid This is a prerequisite for the system to conduct structural change assessment; The input to this formula is the current measurement. and benchmark value ;when The absolute value exceeds the preset system capacitance fluctuation limit. ,For example A fluctuation of 20% indicates that the system has identified a possible structural change. To further adapt to normal system topology changes and avoid long-term false alarms, as defined in Example 5, the dynamic evaluation unit also has an adaptive update function for the reference baseline; its internal logic is: responding to system structure change factors The capacitance fluctuation value continues to exceed the preset limit. Reach a preset duration For example, every 3 hours, the system will prompt the maintenance personnel to update the capacitor reference value. If the maintenance personnel confirm that this change is a legitimate and permanent system change and issue a confirmation command, the system will respond to the command and adopt the new, stabilized capacitor value as the new reference value. .

[0024] Example 6: The trend prediction unit processes the real insulation resistance time series within a preset time window and calculates the relative loss rate of insulation resistance per unit time to obtain the insulation aging rate. This embodiment illustrates how the trend prediction unit in Embodiment 1 calculates the insulation aging rate. This method aims to quantify the trend of insulation performance degradation. The trend prediction unit predicts the actual insulation resistance within a preset time window. The time series data is processed to calculate the relative loss rate of insulation resistance per unit time, thereby obtaining the insulation aging rate. The calculation formula is as follows: ; The formula input is a segment of length... History Data sequence, { },in Represents the first in the time series The actual insulation resistance value of each sampling point For example, if the data point is taken from the past 24 hours, then... ,and The time interval between two measurements is, for example, 1 hour; the formula calculates the time within the time window. Within each time interval Inside The relative rate of decrease, and their arithmetic mean; output Its physical dimension is the reciprocal of time. A consistently positive The value indicates that the system insulation is continuously degrading; To ensure robustness of computation, in actual calculations, it is necessary to... The value is preprocessed; if a certain value is detected... If a value approaches zero due to a serious fault or sensor malfunction, the system should skip the calculation or mark it as abnormal and directly trigger a high-level alarm to prevent calculation errors involving division by zero.

[0025] Example 7: The process by which the comprehensive risk decision-making unit calculates the comprehensive risk index includes: The insulation health index, the system structure change factor normalized by the preset capacitance fluctuation limit, and the insulation aging rate normalized by the preset aging rate threshold are multiplied by their respective preset weight coefficients and then summed to obtain the comprehensive risk index. This embodiment specifically defines the calculation of the comprehensive risk index by the comprehensive risk decision-making unit in Embodiment 1. Fusion algorithm; This calculation process aims to integrate risk information from multiple dimensions into a single indicator; specifically, this unit will incorporate the insulation health index. After the preset capacitance fluctuation limit Normalized system structure change factor and the preset aging rate threshold. Normalized insulation aging rate Each factor is multiplied by its corresponding preset weighting coefficient and then summed to obtain the comprehensive risk index. The calculation formula is as follows: ; In this formula, all inputs are dynamic values ​​calculated in previous steps; to ensure dimensional consistency, The absolute value is determined by its alarm threshold. Normalization By its alarm threshold Normalization ensures that all terms involved in the weighted calculation are dimensionless. To ensure the validity of the calculation, a preset capacitance fluctuation limit is used. With aging rate threshold All should be set to non-zero positive numbers; among them, It is an unacceptable aging rate threshold set based on the characteristics of equipment materials or long-term operation and maintenance experience data. For example, based on the life curve of the insulation material of a specific cable, the threshold is set when the average relative loss rate of insulation resistance per unit time exceeds 5%. They are dimensionless weighting coefficients that satisfy... Its value can be adjusted according to the operation and maintenance strategy; for example, if the focus is on real-time security, it can be set to If the focus is on predictive maintenance, it can improve... The weight.

[0026] Example 8: The process of implementing tiered early warning by the integrated risk decision-making unit includes: When the comprehensive risk index is lower than the first warning threshold, it is determined to be in a normal state; When the comprehensive risk index reaches the first warning threshold but is lower than the second warning threshold, a level of attention alert is triggered. When the comprehensive risk index is not lower than the second warning threshold, a warning level alarm is triggered; Based on Example 1, this embodiment clarifies the specific logic of the comprehensive risk decision-making unit in executing tiered early warning; This unit is based on the comprehensive risk index calculated in the previous step. and two preset warning thresholds That is, the first warning threshold, and That is, the second warning threshold, and meets the following conditions. The thresholds are set based on statistical analysis of historical fault data and the operational response capabilities corresponding to different risk levels, and the following hierarchical logic is executed: Normal state: When the comprehensive risk index Below the first warning threshold When the system is in normal operating condition, no alarm or prompt will be generated. Level 1 Warning (Attention Level): When the comprehensive risk index... The first warning threshold has been reached. But it is below the second warning threshold. When this happens, the system triggers a level-of-concern alert; this status usually indicates an anomaly in a non-core system indicator, but the immediate isolation index... It remains within safe limits and is intended to alert operations and maintenance personnel to this issue. Level 2 Warning (Alert Level): When the comprehensive risk index... Not lower than the second warning threshold When this occurs, the system triggers a warning-level audible and visual alarm; this status indicates that the overall risk has reached a high level, requiring immediate intervention and investigation by maintenance personnel.

[0027] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention; any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0028] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A leakage current protection system for low-voltage IT power supply systems, characterized in that, include: Impedance spectrum identification unit is used to inject a preset composite voltage signal and acquire the total leakage current response to ground in order to construct the original spectrum dataset; Based on the original spectrum dataset, the system's complex impedance spectrum to ground is calculated. Furthermore, by applying the parallel RC equivalent circuit model, the actual insulation resistance and system-to-ground capacitance are decoupled based on the system-to-ground complex impedance spectrum. The dynamic evaluation unit is used to construct an insulation health index based on the actual insulation resistance and the preset insulation resistance alarm limit. Based on the system's capacitance to ground and a preset capacitance reference value, the system structure variation factor is calculated; The trend prediction unit is used to calculate the insulation aging rate based on a time series formed from historical real insulation resistance data; The comprehensive risk decision-making unit is used to combine the insulation health index, system structure change factor and insulation aging rate in a weighted fusion to calculate the comprehensive risk index; Implement tiered early warning systems based on a comprehensive risk index; Furthermore, it outputs a trip signal in response to the insulation health index exceeding the preset final protection limit.

2. The leakage current protection system for low-voltage IT power supply systems according to claim 1, characterized in that, The process by which the impedance spectrum identification unit calculates the complex impedance spectrum of the ground includes: Using the complex Ohm's law, the injection voltage and total ground leakage current response at each frequency point in the original spectrum dataset are calculated to generate complex impedance values ​​including equivalent resistance and equivalent reactance, thus forming the system's complex impedance spectrum to ground.

3. The leakage current protection system for low-voltage IT power supply systems according to claim 1, characterized in that, The process by which the impedance spectrum identification unit decouples the actual insulation resistance and the system-to-ground capacitance includes: The least squares method is used to optimize the model, and the actual insulation resistance and system-to-ground capacitance values ​​are determined by numerical optimization algorithm, so that the sum of squared errors between the theoretical impedance calculated based on the value and the system-to-ground complex impedance spectrum is minimized.

4. The leakage current protection system for low-voltage IT power supply systems according to claim 1, characterized in that, The dynamic evaluation unit calculates the insulation health index by dividing the preset insulation resistance alarm limit by the actual insulation resistance.

5. The leakage current protection system for low-voltage IT power supply systems according to claim 1, characterized in that, The dynamic evaluation unit calculates the difference between the system's capacitance to ground and a preset capacitance reference value, and divides the difference by the capacitance reference value to obtain the system structure change factor.

6. The leakage current protection system for low-voltage IT power supply systems according to claim 5, characterized in that, The dynamic evaluation unit is also used for: When the system structure change factor continues to exceed the preset capacitance fluctuation limit for a preset duration, a prompt is made to update the capacitance reference value. In response to the confirmation command, the capacitance reference value is updated with a new stable capacitance value.

7. The leakage current protection system for low-voltage IT power supply systems according to claim 1, characterized in that, The trend prediction unit processes the actual insulation resistance time series within a preset time window and calculates the relative loss rate of insulation resistance per unit time to obtain the insulation aging rate.

8. The leakage current protection system for low-voltage IT power supply systems according to claim 1, characterized in that, The process by which the comprehensive risk decision-making unit calculates the comprehensive risk index includes: The comprehensive risk index is obtained by multiplying the insulation health index, the system structure change factor normalized by the preset capacitance fluctuation limit, and the insulation aging rate normalized by the preset aging rate threshold by their respective preset weighting coefficients.

9. The leakage current protection system for low-voltage IT power supply systems according to claim 1, characterized in that, The process by which the integrated risk decision-making unit executes tiered early warning includes: When the comprehensive risk index is lower than the first warning threshold, it is determined to be in a normal state; When the comprehensive risk index reaches the first warning threshold but is lower than the second warning threshold, a level of attention alert is triggered. When the comprehensive risk index is not lower than the second warning threshold, a warning level alarm is triggered.

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