Current secondary circuit N line breakage early warning method, device, equipment and medium

Abstract

The invention discloses a current secondary circuit N line breakage early warning method, device and equipment and a medium, and belongs to the field of power systems, and the method comprises the steps: obtaining a current N line current value, a current rated fundamental wave current and a current phase current value of a current secondary circuit; then, calculating a harmonic component attenuation rate, a fundamental wave deviation rate and a difference absolute value; when the absolute value of the difference value exceeds a threshold value in a plurality of continuous power frequency periods, calculating an N-line health index based on a harmonic component attenuation rate, a fundamental wave deviation rate and a temperature rise coefficient; and if the health index is lower than a threshold value, outputting an early warning instruction. Therefore, by implementing the method and the device, the problem that the hidden defects of the N line in the current secondary circuit are difficult to identify in advance and continuously monitor in the prior art can be solved.

Description

Technical Field

[0001] This invention relates to the field of power systems, and in particular to a method, device, equipment, and medium for early warning of a broken N-line in a current secondary circuit. Background Technology

[0002] In modern power systems, the current secondary circuit is the nerve ending of relay protection, measurement, and metering devices. The N line (neutral line) in the current secondary circuit plays a crucial role in forming a complete current path and providing an accurate signal reference. If the N line experiences hidden defects such as a broken wire or poor contact, it will directly lead to distorted sampling by the protection device, which may cause malfunctions or failures to operate, thus posing a serious threat to the power grid equipment and its stable operation.

[0003] In existing technologies, mainstream neutral (N) line status monitoring schemes are mainly divided into two categories. One is the threshold-based scheme, which identifies a broken wire by determining whether the phase current exceeds a certain threshold and the N line current is zero. Because this scheme relies on milliampere-level current sampling accuracy, it can only capture a complete broken wire state and cannot identify gradual increases in contact resistance caused by loose terminals or oxidation. The other is the event-triggered scheme, which relies on current changes generated by specific events such as circuit breaker closing or external faults to trigger the detection logic. Since this scheme cannot be activated under normal, fault-free operating conditions, it has a continuous monitoring blind spot.

[0004] Since neither of the aforementioned technologies can continuously and with high sensitivity monitor latent defects such as loose neutral wire crimping and poor terminal connections during normal system operation, these solutions are essentially reactive and cannot provide early warning of line breakage risks. These latent defects accumulate and worsen under non-fault conditions, potentially leading to malfunctions in protection devices during fault-free periods or failure to operate during actual faults, thus becoming a prominent hidden danger affecting the safe and reliable operation of power systems. Summary of the Invention

[0005] This invention provides a method, device, equipment, and medium for early warning of neutral (N) line disconnection in a current secondary circuit, which can solve the problem of difficulty in identifying latent defects in the neutral (N) line of a current secondary circuit in advance in the prior art.

[0006] In a first aspect, embodiments of the present invention provide a method for early warning of open circuit of the neutral (N) line in a current secondary circuit, comprising: Obtain the current N-line current value, the current rated fundamental current, and the current phase current value of the current secondary circuit; The attenuation rate of the current harmonic component is obtained based on the amplitude of each harmonic corresponding to the current N-line current value, and the current fundamental deviation rate is obtained based on the current rated fundamental current and the current N-line current value. Based on the current phase current value and the current N-line current value, obtain the absolute value of the current difference; If the absolute value of the current difference is greater than or equal to the first preset threshold for a first preset number of consecutive power frequency cycles, then the current NHI value is calculated using the N-line health index calculation formula based on the current harmonic component attenuation rate, the current fundamental frequency deviation rate, and the preset temperature rise coefficient. If the current NHI value is less than or equal to the second preset threshold, an N-line disconnection warning command for the current secondary circuit is output.

[0007] This application embodiment first acquires key current data related to the neutral (N) line in the secondary current circuit to provide a foundation for subsequent monitoring. Then, by calculating the harmonic component attenuation rate, fundamental frequency deviation rate, and the absolute value of the difference between the phase current and the N line current, it accurately captures subtle changes in the N line's state during operation. Even in the face of latent defects such as loose terminals or oxidation leading to a gradual increase in contact resistance, it can be detected in a timely manner. Subsequently, by monitoring the difference over multiple consecutive power frequency cycles and combining health index calculations with multiple parameters, the health status of the N line is comprehensively assessed, eliminating the dependence on specific event triggers and achieving continuous monitoring during normal system operation. Finally, based on the health index threshold, an early warning command is output, enabling risk prediction before the N line is completely disconnected. This breaks the limitations of traditional post-event judgment and effectively avoids maloperation or failure to operate of protection devices due to N line problems, providing strong protection for the safe and stable operation of the power system.

[0008] As a preferred example of the first aspect, the step of obtaining the attenuation rate of the current harmonic component based on the harmonic amplitudes corresponding to the current N-line current value includes: Match the harmonic amplitude values ​​corresponding to the N-line current value in the previous power frequency cycle with the harmonic amplitude values ​​corresponding to the current N-line current value to obtain the harmonic amplitude pairs corresponding to each order. The attenuation rate of the current harmonic component is calculated using the harmonic component attenuation rate calculation formula based on the harmonic amplitude pairs corresponding to each order.

[0009] This application's embodiment matches the harmonic amplitudes of the N-line current in the previous power frequency cycle with those in the current power frequency cycle, and then calculates the harmonic component attenuation rate based on the matched harmonic amplitudes. This allows for accurate capture of the changing trends of harmonic components in the N-line current and timely detection of changes in harmonic propagation characteristics caused by latent defects such as loose terminals and oxidation. This order-matching-based calculation method makes the acquisition of harmonic component attenuation rates more targeted and comprehensive, avoiding the limitations of single-cycle data. The calculation results more accurately reflect the actual operating status of the N-line, providing reliable parameter support for the subsequent accurate assessment of the N-line health index.

[0010] As a preferred example of the first aspect, the calculation of the current NHI value based on the current harmonic component attenuation rate, the current fundamental frequency deviation rate, and a preset temperature rise coefficient using the N-line health index calculation formula includes: The first health component is obtained based on the current fundamental frequency deviation rate and the first preset weighting coefficient; The second health component is obtained based on the current harmonic component attenuation rate and the second preset weighting coefficient. The third health component is obtained based on the temperature rise coefficient and the third preset weighting coefficient; The current NHI value is calculated using the N-line health index calculation formula based on the first health component, the second health component, and the third health component.

[0011] This application embodiment extracts three health components from the fundamental frequency deviation rate, harmonic component attenuation rate, and temperature rise coefficient by combining corresponding weight coefficients. These three components are then integrated and calculated using a specific formula to obtain the N-line health index (NHI value). This not only specifically considers the weight of different influencing factors on the health status of the N-line, but also comprehensively covers the core dimensions reflecting the operating status of the N-line, avoiding the one-sidedness of a single indicator assessment.

[0012] As a preferred example of the first aspect, the calculation of the current NHI value using the N-line Health Index calculation formula based on the first health component, the second health component, and the third health component includes: The current NHI value is calculated using the N-line health index calculation formula based on the first health component, the second health component, and the third health component. The N-line health index calculation formula is as follows: in, This represents the current fundamental frequency deviation rate. This represents the current harmonic component attenuation rate. The preset temperature rise coefficient, The current NHI value, , and These are the first preset weight coefficient, the second preset weight coefficient, and the third preset weight coefficient, respectively.

[0013] This application's embodiment obtains the NHI value by subtracting the fundamental frequency deviation rate, harmonic component attenuation rate, and temperature rise coefficient adjusted with corresponding weighting coefficients from the baseline value. This comprehensively integrates the three key factors affecting the health status of the N-line and reasonably distinguishes the degree of influence of each factor on the N-line operation through weighting settings, avoiding the one-sidedness of single-indicator evaluation. This quantitative calculation method can transform complex N-line operating parameters into an intuitive and easy-to-understand health index, allowing for an accurate and objective presentation of the actual health status of the N-line, and providing a scientific and reliable quantitative basis for subsequent judgment on whether to issue a line breakage warning.

[0014] As a preferred example of the first aspect, obtaining the current N-line current value, the current rated fundamental current, and the current phase current value of the current secondary circuit includes: The current original N-line current value is obtained through a zero-flux current sensor, and the current original phase current value is obtained through a CT sampling module; The current original N-line current value and the current original phase current value are time-synchronized to obtain the current N-line current value, the current rated fundamental current, and the current phase current value; wherein, the current rated fundamental current is obtained based on the current N-line current value.

[0015] This application embodiment uses a professional zero-flux current sensor and a CT sampling module to collect the original N-line current value and the original phase current value respectively, which can ensure that the acquired basic data is true and reliable and reduce the error interference of the original data. The time-stamped synchronization processing of the two types of original current values ​​can keep the current data from different sources consistent in the time dimension, providing a data foundation for accurate matching for subsequent calculation of various parameters.

[0016] As a preferred example of the first aspect, obtaining the absolute value of the current difference based on the current phase current value and the current N-line current value includes: Based on the current phase current value and the current N-line current value, the absolute value of the difference is calculated using the formula for the absolute value of the difference, which is as follows: in, This is the absolute value of the current difference. This is the current phase current value. This is the current value of the N-line.

[0017] This application's embodiments directly compare the phase current value and the neutral (N) line current value, using the absolute value formula of the difference to calculate the degree of difference between the two, which can intuitively reflect whether the matching state of the two types of currents is normal. This calculation method is simple and direct, and can quickly detect current imbalance problems caused by hidden defects such as poor contact or loosening of the neutral (N) line.

[0018] As a preferred example of the first aspect, the process of obtaining the current fundamental frequency deviation rate based on the current rated fundamental current and the current neutral line current includes: Based on the current rated fundamental current and the current neutral line current, the current fundamental deviation rate is calculated using the fundamental deviation formula, which is as follows: in, This is the current N-line current value. This is the current rated fundamental current.

[0019] This application's embodiment calculates the fundamental deviation rate by substituting the current N-line current value and the rated fundamental current into the fundamental deviation formula. This allows for a direct quantification of the actual N-line current's deviation from the rated reference, accurately capturing current operation anomalies caused by latent defects such as loose terminals or oxidation. This reference-based calculation method effectively reflects whether the N-line current deviates from the normal operating range, providing key parameters reflecting current reference deviation for the subsequent comprehensive evaluation of the N-line health index.

[0020] Secondly, the present invention provides a current secondary circuit N-line disconnection early warning device, comprising: a data acquisition module, a first processing module, a second processing module, a third processing module, and an early warning module; The data acquisition module is used to acquire the current N-line current value, the current rated fundamental current, and the current phase current value of the current secondary circuit; The first processing module is used to obtain the current harmonic component attenuation rate based on the harmonic amplitude values ​​corresponding to the current N-line current value, and to obtain the current fundamental frequency deviation rate based on the current rated fundamental frequency current and the current N-line current value. The second processing module is used to obtain the absolute value of the current difference based on the current phase current value and the current N-line current value; The third processing module is used to calculate the current NHI value based on the current harmonic component attenuation rate, the current fundamental frequency deviation rate and the preset temperature rise coefficient when the absolute value of the current difference is greater than or equal to the first preset threshold for a first preset number of consecutive power frequency cycles. The early warning module is used to output an early warning command for the N-line disconnection of the current secondary circuit if the current NHI value is less than or equal to the second preset threshold.

[0021] As a preferred example of the second aspect, the step of obtaining the attenuation rate of the current harmonic component based on the harmonic amplitudes corresponding to the current N-line current value includes: Match the harmonic amplitude values ​​corresponding to the N-line current value in the previous power frequency cycle with the harmonic amplitude values ​​corresponding to the current N-line current value to obtain the harmonic amplitude pairs corresponding to each order. The attenuation rate of the current harmonic component is calculated using the harmonic component attenuation rate calculation formula based on the harmonic amplitude pairs corresponding to each order.

[0022] As a preferred example of the second aspect, the calculation of the current NHI value based on the current harmonic component attenuation rate, the current fundamental frequency deviation rate, and a preset temperature rise coefficient using the N-line health index calculation formula includes: The first health component is obtained based on the current fundamental frequency deviation rate and the first preset weighting coefficient; The second health component is obtained based on the current harmonic component attenuation rate and the second preset weighting coefficient. The third health component is obtained based on the temperature rise coefficient and the third preset weighting coefficient; The current NHI value is calculated using the N-line health index calculation formula based on the first health component, the second health component, and the third health component.

[0023] As a preferred example of the second aspect, the calculation of the current NHI value based on the first health component, the second health component, and the third health component using the N-line health index calculation formula includes: The current NHI value is calculated using the N-line health index calculation formula based on the first health component, the second health component, and the third health component. The N-line health index calculation formula is as follows: in, This represents the current fundamental frequency deviation rate. This represents the current harmonic component attenuation rate. The preset temperature rise coefficient, The current NHI value, , and These are the first preset weight coefficient, the second preset weight coefficient, and the third preset weight coefficient, respectively.

[0024] As a preferred example of the second aspect, obtaining the current N-line current value, the current rated fundamental current, and the current phase current value of the current secondary circuit includes: The current original N-line current value is obtained through a zero-flux current sensor, and the current original phase current value is obtained through a CT sampling module; The current original N-line current value and the current original phase current value are time-synchronized to obtain the current N-line current value, the current rated fundamental current, and the current phase current value; wherein, the current rated fundamental current is obtained based on the current N-line current value.

[0025] As a preferred example of the second aspect, obtaining the absolute value of the current difference based on the current phase current value and the current N-line current value includes: Based on the current phase current value and the current N-line current value, the absolute value of the difference is calculated using the formula for the absolute value of the difference, which is as follows: in, This is the absolute value of the current difference. This is the current phase current value. This is the current value of the N-line.

[0026] As a preferred example of the second aspect, the process of obtaining the current fundamental frequency deviation rate based on the current rated fundamental current and the current neutral line current includes: Based on the current rated fundamental current and the current neutral line current, the current fundamental deviation rate is calculated using the fundamental deviation formula, which is as follows: in, This is the current N-line current value. This is the current rated fundamental current.

[0027] In summary, this application's embodiments first acquire key current data related to the neutral (N) line in the secondary current circuit, providing a foundation for subsequent monitoring. Then, by calculating the harmonic component attenuation rate, fundamental frequency deviation rate, and the absolute value of the difference between the phase current and the N line current, it accurately captures subtle state changes of the N line during operation. Even in situations where latent defects such as loose terminals or oxidation cause a gradual increase in contact resistance, it can be detected in a timely manner. Subsequently, by monitoring the difference over multiple consecutive power frequency cycles and combining health index calculations with various parameters, the health status of the N line is comprehensively assessed, eliminating the dependence on specific event triggers and achieving continuous monitoring during normal system operation. Finally, based on the health index threshold, an early warning command is output, enabling risk prediction before the N line is completely disconnected. This breaks the limitations of traditional post-event judgment, effectively preventing protection devices from malfunctioning or failing to operate due to N line problems, and providing strong protection for the safe and stable operation of the power system.

[0028] Another embodiment of the present invention provides a terminal device, including: a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the steps of the current secondary circuit N-line disconnection early warning method of the present invention.

[0029] Another embodiment of the present invention provides a computer-readable storage medium item, including: a stored computer program, which, when the computer program is running, controls the device where the computer-readable storage medium is located to perform the steps of the current secondary circuit N-line disconnection early warning method of the present invention. Attached Figure Description

[0030] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0031] Figure 1A flowchart illustrating an embodiment of a current secondary circuit N-line disconnection early warning method provided by the present invention; Figure 2 A schematic diagram of an embodiment of a current secondary circuit N-line disconnection early warning method provided by the present invention; Figure 3 This is a module structure diagram of an embodiment of a current secondary circuit N-line disconnection early warning device provided by the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0034] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0035] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0036] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0037] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0038] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0039] Example 1 See Figure 1 To address the problem of difficulty in identifying latent defects in the neutral (N) wire of a current secondary circuit in advance, an embodiment of the present invention provides a method for early warning of neutral wire disconnection in a current secondary circuit, comprising: S1. Obtain the current N-line current value, the current rated fundamental current, and the current phase current value of the current secondary circuit; In a preferred embodiment, obtaining the current N-line current value, the current rated fundamental current, and the current phase current value of the current secondary circuit includes: The current original N-line current value is obtained through a zero-flux current sensor, and the current original phase current value is obtained through a CT sampling module; The current original N-line current value and the current original phase current value are time-synchronized to obtain the current N-line current value, the current rated fundamental current, and the current phase current value; wherein, the current rated fundamental current is obtained based on the current N-line current value.

[0040] Specifically, such as Figure 2 As shown, the zero-flux current sensor and the temperature-compensated operational amplifier circuit form a high-precision N-line monitoring unit, deployed within the protection cabinet. The zero-flux current sensor includes a toroidal core, a primary winding, and a secondary compensation winding. The primary winding is connected in series with the N-line circuit, and the secondary compensation winding is connected to a current feedback circuit. The output of the feedback circuit is connected to the negative feedback loop of the temperature-compensated operational amplifier circuit. The temperature-compensated operational amplifier circuit adopts a differential amplification architecture, including a thermistor bridge and a programmable gain amplifier. The resistance of the thermistor bridge varies linearly with the ambient temperature from -25℃ to 70℃, and the gain adjustment step of the programmable gain amplifier is 0.1dB.

[0041] For example, the preferred measurement accuracy of the zero flux current sensor is ±0.5. .

[0042] Specifically, such as Figure 2 As shown, the time-scale synchronization of the current original N-line current value and the current original phase current value can be performed through a source data verification unit. This source data verification unit includes a time-scale synchronization module, which is used to align the timescales of the current original N-line current value and the current original phase current value. The time-scale synchronization module employs a power frequency cycle time-division sampling mechanism.

[0043] S2. Calculate the attenuation rate of the current harmonic component based on the amplitude of each harmonic corresponding to the current N-line current value, and calculate the current fundamental deviation rate based on the current rated fundamental current and the current N-line current value. As a preferred embodiment, the step of obtaining the attenuation rate of the current harmonic component based on the harmonic amplitudes corresponding to the current N-line current value includes: Match the harmonic amplitude values ​​corresponding to the N-line current value in the previous power frequency cycle with the harmonic amplitude values ​​corresponding to the current N-line current value to obtain the harmonic amplitude pairs corresponding to each order. The attenuation rate of the current harmonic component is calculated using the harmonic component attenuation rate calculation formula based on the harmonic amplitude pairs corresponding to each order.

[0044] Specifically, the formula for calculating the harmonic component attenuation rate is as follows: in, For the current moment Second harmonic amplitude For the previous power frequency cycle At the same time Second harmonic amplitude.

[0045] As a preferred embodiment, the step of obtaining the current fundamental frequency deviation rate based on the current rated fundamental current and the current neutral line current includes: Based on the current rated fundamental current and the current neutral line current, the current fundamental deviation rate is calculated using the fundamental deviation formula, which is as follows: in, This is the current N-line current value. This is the current rated fundamental current.

[0046] The attenuation rate of the current harmonic component is calculated using the harmonic component attenuation rate calculation formula based on the harmonic amplitude pairs corresponding to each order.

[0047] S3. Based on the current phase current value and the current N-line current value, obtain the absolute value of the current difference; As a preferred embodiment, obtaining the absolute value of the current difference based on the current phase current value and the current N-line current value includes: Based on the current phase current value and the current N-line current value, the absolute value of the difference is calculated using the formula for the absolute value of the difference, which is as follows: in, This is the absolute value of the current difference. This is the current phase current value. This is the current value of the N-line.

[0048] Specifically, such as Figure 2 As shown, the dynamic comparison module can obtain the absolute value of the current difference based on the current phase current value and the current N-line current value.

[0049] S4. If the absolute value of the current difference is greater than or equal to the first preset threshold for a first preset number of consecutive power frequency cycles, then the current NHI value is obtained by using the N-line health index calculation formula based on the current harmonic component attenuation rate, the current fundamental frequency deviation rate and the preset temperature rise coefficient. Preferably, the first preset number can be 3, and the first preset threshold can be in the range of 3 to 10. The reason for choosing 3 cycles is that exceeding the threshold within a single cycle (20ms) may be caused by transient interference, which is an occasional event; exceeding the threshold for 2 consecutive cycles may be a short-term system fluctuation; exceeding the threshold for 3 consecutive cycles can be determined as a continuous anomaly, which is likely due to a defect in the N line itself (loose terminals causing a continuous increase in contact resistance).

[0050] Furthermore, the first preset threshold Based on the harmonic component attenuation rate Dynamic adjustment: when ;when ;when The formula is as follows: As a preferred implementation, a first health component is obtained based on the current fundamental frequency deviation rate and a first preset weighting coefficient; The second health component is obtained based on the current harmonic component attenuation rate and the second preset weighting coefficient. The third health component is obtained based on the temperature rise coefficient and the third preset weighting coefficient; The current NHI value is calculated using the N-line health index calculation formula based on the first health component, the second health component, and the third health component.

[0051] In some preferred embodiments, the step of calculating the current NHI value using the N-line health index calculation formula based on the first health component, the second health component, and the third health component includes: The current NHI value is calculated using the N-line health index calculation formula based on the first health component, the second health component, and the third health component. The N-line health index calculation formula is as follows: in, This represents the current fundamental frequency deviation rate. This represents the current harmonic component attenuation rate. The preset temperature rise coefficient, The current NHI value, , and These are the first preset weight coefficient, the second preset weight coefficient, and the third preset weight coefficient, respectively.

[0052] It should be noted that the weighting coefficients and parameter calculation methods of the NHI model were determined based on statistical analysis of 1000 N-line defect cases: by performing regression analysis on the correlation between the actual defect severity and each parameter, it was found that... The correlation coefficient with the degree of defect reached 0.8. It is 0.6. The value was set to 0.4, hence the corresponding weight. The model was also optimized through field experiments. For example, in 200 sets of normal operation data, the NHI was ≥85; in 50 sets of minor defect data, the NHI was between 70 and 85; and in 30 sets of severe defect data, the NHI was <70, verifying the model's reliability.

[0053] Specifically, the preset temperature rise coefficient can be obtained by a temperature sensor mounted on the N-line terminal.

[0054] Preferably, the preferred values ​​for the weighting coefficients are: .

[0055] S5. If the current NHI value is less than or equal to the second preset threshold, output the N-line disconnection warning command of the current secondary circuit.

[0056] Preferably, the second preset threshold is 70, and the NHI value ranges from 0 to 100, with a higher value indicating a better health status of the N-line. Figure 2 As shown, when the NHI value calculated by the health assessment unit is lower than the set threshold of 70, a minute-level disconnection risk warning command is triggered.

[0057] In summary, this application's embodiments first acquire key current data related to the neutral (N) line in the secondary current circuit, providing a foundation for subsequent monitoring. Then, by calculating the harmonic component attenuation rate, fundamental frequency deviation rate, and the absolute value of the difference between the phase current and the N line current, it accurately captures subtle state changes of the N line during operation. Even in situations where latent defects such as loose terminals or oxidation cause a gradual increase in contact resistance, it can be detected in a timely manner. Subsequently, by monitoring the difference over multiple consecutive power frequency cycles and combining health index calculations with various parameters, the health status of the N line is comprehensively assessed, eliminating the dependence on specific event triggers and achieving continuous monitoring during normal system operation. Finally, based on the health index threshold, an early warning command is output, enabling risk prediction before the N line is completely disconnected. This breaks the limitations of traditional post-event judgment, effectively preventing protection devices from malfunctioning or failing to operate due to N line problems, and providing strong protection for the safe and stable operation of the power system.

[0058] Example 2 like Figure 3 As shown, based on the above method embodiments, corresponding device embodiments are provided; An embodiment of the present invention provides a current secondary circuit N-line disconnection early warning device, comprising: a data acquisition module 31, a first processing module 32, a second processing module 33, a third processing module 34, and an early warning module 35; Data acquisition module 31 is used to acquire the current N-line current value, the current rated fundamental current and the current phase current value of the current secondary circuit; The first processing module 32 is used to obtain the current harmonic component attenuation rate based on the harmonic amplitude values ​​corresponding to the current N-line current value, and to obtain the current fundamental deviation rate based on the current rated fundamental current and the current N-line current value. The second processing module 33 is used to obtain the absolute value of the current difference based on the current phase current value and the current N-line current value; The third processing module 34 is used to calculate the current NHI value based on the current harmonic component attenuation rate, the current fundamental frequency deviation rate and the preset temperature rise coefficient when the absolute value of the current difference is greater than or equal to the first preset threshold for a first preset number of consecutive power frequency cycles. The early warning module 35 is used to output an early warning command for the N-line disconnection of the current secondary circuit if the current NHI value is less than or equal to the second preset threshold.

[0059] As a preferred embodiment, the step of obtaining the attenuation rate of the current harmonic component based on the harmonic amplitudes corresponding to the current N-line current value includes: Match the harmonic amplitude values ​​corresponding to the N-line current value in the previous power frequency cycle with the harmonic amplitude values ​​corresponding to the current N-line current value to obtain the harmonic amplitude pairs corresponding to each order. The attenuation rate of the current harmonic component is calculated using the harmonic component attenuation rate calculation formula based on the harmonic amplitude pairs corresponding to each order.

[0060] As a preferred embodiment, the step of calculating the current NHI value using the N-line health index calculation formula based on the current harmonic component attenuation rate, the current fundamental frequency deviation rate, and a preset temperature rise coefficient includes: The first health component is obtained based on the current fundamental frequency deviation rate and the first preset weighting coefficient; The second health component is obtained based on the current harmonic component attenuation rate and the second preset weighting coefficient. The third health component is obtained based on the temperature rise coefficient and the third preset weighting coefficient; The current NHI value is calculated using the N-line health index calculation formula based on the first health component, the second health component, and the third health component.

[0061] In a preferred embodiment, the step of calculating the current NHI value using the N-line Health Index calculation formula based on the first health component, the second health component, and the third health component includes: The current NHI value is calculated using the N-line health index calculation formula based on the first health component, the second health component, and the third health component. The N-line health index calculation formula is as follows: in, This represents the current fundamental frequency deviation rate. This represents the current harmonic component attenuation rate. The preset temperature rise coefficient, The current NHI value, , and These are the first preset weight coefficient, the second preset weight coefficient, and the third preset weight coefficient, respectively.

[0062] In a preferred embodiment, obtaining the current N-line current value, the current rated fundamental current, and the current phase current value of the current secondary circuit includes: The current original N-line current value is obtained through a zero-flux current sensor, and the current original phase current value is obtained through a CT sampling module; The current original N-line current value and the current original phase current value are time-synchronized to obtain the current N-line current value, the current rated fundamental current, and the current phase current value; wherein, the current rated fundamental current is obtained based on the current N-line current value.

[0063] As a preferred embodiment, obtaining the absolute value of the current difference based on the current phase current value and the current N-line current value includes: Based on the current phase current value and the current N-line current value, the absolute value of the difference is calculated using the formula for the absolute value of the difference, which is as follows: in, This is the absolute value of the current difference. This is the current phase current value. This is the current value of the N-line.

[0064] As a preferred embodiment, the step of obtaining the current fundamental frequency deviation rate based on the current rated fundamental current and the current neutral line current includes: Based on the current rated fundamental current and the current neutral line current, the current fundamental deviation rate is calculated using the fundamental deviation formula, which is as follows: in, This is the current N-line current value. This is the current rated fundamental current.

[0065] In summary, this application's embodiments first acquire key current data related to the neutral (N) line in the secondary current circuit, providing a foundation for subsequent monitoring. Then, by calculating the harmonic component attenuation rate, fundamental frequency deviation rate, and the absolute value of the difference between the phase current and the N line current, it accurately captures subtle state changes of the N line during operation. Even in situations where latent defects such as loose terminals or oxidation cause a gradual increase in contact resistance, it can be detected in a timely manner. Subsequently, by monitoring the difference over multiple consecutive power frequency cycles and combining health index calculations with various parameters, the health status of the N line is comprehensively assessed, eliminating the dependence on specific event triggers and achieving continuous monitoring during normal system operation. Finally, based on the health index threshold, an early warning command is output, enabling risk prediction before the N line is completely disconnected. This breaks the limitations of traditional post-event judgment, effectively preventing protection devices from malfunctioning or failing to operate due to N line problems, and providing strong protection for the safe and stable operation of the power system.

[0066] For more detailed steps and working principles of this embodiment, please refer to the relevant description in Embodiment 1, but not limited to these descriptions.

[0067] In summary, this application's embodiments first acquire key current data related to the neutral (N) line in the secondary current circuit, providing a foundation for subsequent monitoring. Then, by calculating the harmonic component attenuation rate, fundamental frequency deviation rate, and the absolute value of the difference between the phase current and the N line current, it accurately captures subtle state changes of the N line during operation. Even in situations where latent defects such as loose terminals or oxidation cause a gradual increase in contact resistance, it can be detected in a timely manner. Subsequently, by monitoring the difference over multiple consecutive power frequency cycles and combining health index calculations with various parameters, the health status of the N line is comprehensively assessed, eliminating the dependence on specific event triggers and achieving continuous monitoring during normal system operation. Finally, based on the health index threshold, an early warning command is output, enabling risk prediction before the N line is completely disconnected. This breaks the limitations of traditional post-event judgment, effectively preventing protection devices from malfunctioning or failing to operate due to N line problems, and providing strong protection for the safe and stable operation of the power system.

[0068] It is understood that the above-described device embodiments correspond to the method embodiments of the present invention, and can implement the current secondary circuit N-line disconnection early warning method provided by any of the above-described method embodiments of the present invention.

[0069] It should be noted that the device embodiments described above are merely illustrative, and some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can specifically be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0070] Based on the above embodiments of the current secondary circuit N-line disconnection early warning method, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the current secondary circuit N-line disconnection early warning method of any embodiment of the present invention.

[0071] For example, in this embodiment, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the terminal device.

[0072] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0073] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0074] Based on the above-described method embodiments, another embodiment of the present invention provides a computer-readable storage medium including a stored computer program, wherein, when the computer program is executed, it controls the device where the computer-readable storage medium is located to execute the current secondary circuit N-line disconnection early warning method described in any of the above-described method embodiments of the present invention.

[0075] The modules / units integrated in the device / terminal equipment, if implemented as software functional units and sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc.

[0076] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A current secondary circuit N wire disconnection early warning method, characterized in that, The method comprises the following steps: obtaining a current N-line current value, a current rated fundamental current and a current phase current value of the current secondary circuit; obtaining a current harmonic component attenuation rate according to each harmonic amplitude corresponding to the current N-line current value, and obtaining a current fundamental deviation rate according to the current rated fundamental current and the current N-line current value; obtaining a current difference absolute value according to the current phase current value and the current N-line current value; if the current difference absolute value is greater than or equal to a first preset threshold value for a first preset number of power frequency periods in succession, then obtaining a current NHI value by using an N-line health index calculation formula according to the current harmonic component attenuation rate, the current fundamental deviation rate and a preset temperature rise coefficient; if the current NHI value is less than or equal to a second preset threshold value, outputting an N-line disconnection early warning instruction of the current secondary circuit.

2. The current secondary circuit N-wire disconnection early warning method of claim 1, wherein, The method comprises the following steps: matching each harmonic amplitude corresponding to the N-line current value in the last power frequency period and each harmonic amplitude corresponding to the current N-line current value, to obtain a harmonic amplitude pair corresponding to each order; obtaining the current harmonic component attenuation rate by using a harmonic component attenuation rate calculation formula according to the harmonic amplitude pair corresponding to each order.

3. The current secondary circuit N-wire disconnection early warning method of claim 1, wherein, The method comprises the following steps: obtaining a first health degree component according to the current fundamental deviation rate and a first preset weight coefficient; obtaining a second health degree component according to the current harmonic component attenuation rate and a second preset weight coefficient; obtaining a third health degree component according to the temperature rise coefficient and a third preset weight coefficient; obtaining the current NHI value by using the N-line health index calculation formula according to the first health degree component, the second health degree component and the third health degree component.

4. The current secondary circuit N-wire disconnection early warning method of claim 3, wherein, The method comprises the following steps: The N-line health index calculation formula is as follows: wherein, is a current fundamental deviation rate, is a current harmonic component decay rate, is a preset temperature rise coefficient, is a current NHI value, , and are a first preset weight coefficient, a second preset weight coefficient, and a third preset weight coefficient, respectively.

5. The current secondary circuit N-wire disconnection early warning method of claim 1, wherein, The method comprises the following steps: obtaining a current original N-line current value by using a zero-magnetic-flux current sensor, and obtaining a current original phase current value by using a CT sampling module; synchronizing the current original N-line current value and the current original phase current value in time, to obtain the current N-line current value, the current rated fundamental current and the current phase current value; wherein the current rated fundamental current is obtained according to the current N-line current value.

6. The current secondary circuit N-wire disconnection early warning method of claim 1, wherein, The method comprises the following steps: obtaining the current difference absolute value by using a difference absolute value formula according to the current phase current value and the current N-line current value; wherein the difference absolute value formula is as follows: wherein, is the current difference absolute value, is the current phase current value, is the current N-line current value.

7. The current secondary circuit N-wire disconnection early warning method of claim 1, wherein, The current fundamental deviation rate is obtained according to the current rated fundamental current and the current N-line current value, and the method comprises the following steps: The current fundamental deviation rate is obtained according to the current rated fundamental current and the current N-line current value by using a fundamental deviation formula, wherein the fundamental deviation formula is as follows: wherein, is the current N-line current value, is the current rated fundamental current.

8. A current secondary circuit N-wire disconnection early warning device, characterized in that, The method comprises the following steps: The method comprises the following steps: The data acquisition module is configured to acquire the current N-line current value, the current rated fundamental current and the current phase current value of the current secondary circuit. The first processing module is configured to obtain a current harmonic component attenuation rate according to the harmonic amplitudes corresponding to the current N-line current value, and obtain a current fundamental deviation rate according to the current rated fundamental current and the current N-line current value. The second processing module is configured to obtain a current difference absolute value according to the current phase current value and the current N-line current value. The third processing module is configured to, if the current difference absolute value is greater than or equal to a first preset threshold value for a first preset number of power frequency periods, obtain a current NHI value according to the current harmonic component attenuation rate, the current fundamental deviation rate and a preset temperature rise coefficient by using an N-line health index calculation formula. The warning module is configured to output an N-line disconnection warning instruction of the current secondary circuit if the current NHI value is less than or equal to a second preset threshold value.

9. A terminal device, comprising: The computer program is stored in the memory and is configured to be executed by the processor, and when the processor executes the computer program, the current secondary circuit N-line disconnection warning method is implemented.

10. A computer-readable storage medium, characterized in that, The computer program is stored in the memory and is configured to be executed by the processor, and when the processor executes the computer program, the current secondary circuit N-line disconnection warning method is implemented. The computer program is stored in the memory and is configured to be executed by the processor, and when the processor executes the computer program, the current secondary circuit N-line disconnection warning method is implemented.

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