Method for monitoring and alarming residual current increment change rate of outdoor environment alternating current power distribution system

Abstract

The invention relates to a residual current increment change rate monitoring and alarming method for an outdoor environment AC power distribution system. A residual current sensor RCT, a working current sensor CT, an equipment shell fault voltage sensor RVT, an environment temperature sensor TT, an environment humidity sensor HT, a water sensor WT and an information sampling detector are installed in an outdoor distribution box, and the short-term change trend of residual current change is dynamically tracked through residual current abrupt change increment change rate parameters. And rapid residual current increase caused by severe grounding faults such as sudden short circuit is identified, and rapid protection action is carried out. A multi-dimensional alarm mechanism is adopted, in addition to a residual current increment change rate parameter, comprehensive judgment is carried out in combination with parameters such as a residual current absolute value, environment temperature and humidity, a water immersion signal and a fault voltage value, and the alarm accuracy and reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of power distribution network protection, specifically to a method for monitoring and alarming the rate of change of residual current increment in an outdoor AC power distribution system. Background Technology

[0002] Existing residual current monitoring and alarm systems typically employ residual current sensors to collect the real-time absolute value of the residual current in electrical circuits. This value is then compared to a fixed alarm threshold (usually 30mA). If the sampled value exceeds the threshold, an alarm signal is triggered. This method monitors the real-time absolute value of AC residual current in indoor environments; the alarm trigger condition is whether the real-time absolute value of the residual current exceeds the fixed threshold; and the alarm occurs when the insulation of the electrical circuit is severely damaged. This method is highly susceptible to environmental factors, has a high false alarm rate, and is inaccurate, making it only suitable for general locations where real-time insulation monitoring is not critical.

[0003] The total residual current collected by existing technologies includes the sum of natural leakage current under non-fault conditions and residual current under fault conditions, thus it cannot distinguish between normal load fluctuations and abnormal leakage current; it is not sensitive to slowly developing insulation aging; it is prone to false alarms under the influence of environmental factors such as humid weather; and it cannot provide a prediction of the fault development trend.

[0004] Existing technological shortcomings:

[0005] 1. A residual current protection device for a DC traction power supply system for rail transit (Publication No.: CN114629080A). Defect 1: This technical method is applied to a DC traction power supply system for rail transit. DC traction power supply systems are fundamentally different from AC power distribution systems. The sampling methods for residual current are also completely different. This technical method uses the DC current value sampled on the grounding wire by a DC shunt as the DC residual current value, while AC residual current sampling involves passing the phase line (L) and neutral line (N) of the AC power distribution system through the coil of an AC current sensor to sample the AC residual current value. Based on the device configuration, system connection description, and DC residual current sampling method of this technical method, it can be seen that this method directly samples the current on the grounding wire as the DC residual current. Therefore, when the system is working normally, the DC residual current value is 0 (because there is no potential difference on the overhead grounding wire during normal operation, and no current flows). When a leakage fault occurs in the DC traction power supply system, the DC residual current value sampled by this technical method is the same as the current value sampled by the DC shunt. Therefore, the incremental value of the residual current in this method is the real-time absolute value of the DC residual current. The absolute value of the DC residual current includes both natural leakage current and residual current during faults. The natural leakage current of power distribution cables and electrical loads varies with environmental factors and insulation performance, but these changes do not affect normal load operation or pose a risk of electric shock. Therefore, when environmental factors increase the natural leakage current, the absolute value of the sampled residual current also increases, making it easy for the sampled value to exceed a fixed threshold, leading to frequent alarms. This results in management personnel struggling to handle false alarms and perform maintenance, with a high false alarm rate and inaccuracy. It is only suitable for general locations where real-time insulation monitoring is not critical, and not for the more critical rail transit sector.

[0006] Defect 2: This technical method uses only one electrical parameter—DC residual current—as a criterion. This criterion is too simplistic and susceptible to misjudgment due to a single source of information, resulting in inaccurate alarm results. Without knowing environmental parameters and fault voltage values, it's impossible to assess the risk of electric shock from a leakage fault, or whether the power supply system can continue operating under fault conditions to prevent secondary injuries from sudden power outages. If the DC traction power supply system trips its protection suddenly after a leakage fault, the rail transit system will lose power, trapping trains and related auxiliary facilities in tunnels or on elevated tracks, making evacuation difficult and potentially leading to serious consequences. Clearly, after a leakage fault, tiered protection actions should be implemented based on the actual situation at the fault location and the risk of a safety accident. The faulty circuit should only be disconnected after other backup emergency measures are in place, rather than a one-size-fits-all approach of tripping the entire system.

[0007] Defect 3: The residual current sampled by this technical method is a mixture of natural leakage current and fault residual current. When the residual current value increases, it is impossible to distinguish whether the increase is due to the increase in residual current under fault conditions or the increase in natural leakage current under non-fault conditions. Therefore, it is impossible to accurately track the trend of insulation changes and to provide early warning.

[0008] 2. A method for monitoring leakage current in the AC secondary circuit of a synchronous condenser (Publication No.: CN113219366A). This method is applied to the AC secondary control circuit of a synchronous condenser in an indoor environment. The only criterion parameter used is the residual AC current, which is relatively simple and susceptible to misjudgment due to a single source of information, resulting in inaccurate alarm results. Without knowing the environmental parameters and fault voltage values, it is impossible to determine the risk of electric shock from the fault voltage after a leakage fault occurs, or whether the synchronous condenser's secondary circuit can continue operating under fault conditions to prevent secondary injuries from sudden power outages. A sudden loss of power to the synchronous condenser's secondary circuit will cause the synchronous condenser to lose control, affecting the stability of the power system and potentially causing widespread power outages. Therefore, tiered protection actions should be implemented based on the actual situation at the fault site and the risk of a safety accident. The faulty circuit should be disconnected only after other backup emergency measures are implemented, rather than a one-size-fits-all approach of directly tripping and cutting off the system power supply.

[0009] The "inherent residual current" (i.e., the natural leakage current under non-fault conditions) measured in step 1 will change with the decline in insulation performance and changes in environmental conditions, load size, and equipment status. Therefore, this "inherent residual current" is not "inherent" and cannot be measured in advance. If step 2 compares the initially measured "inherent residual current" value as a fixed value with the alarm setting value, it will not match the actual value, and the result will be inaccurate.

[0010] The residual current dynamic compensation in step 3 is essentially the real-time value of the natural leakage current under non-fault conditions. However, for AC power distribution systems, the residual current sampled by this method is a mixture of natural leakage current and fault residual current, and it cannot distinguish whether the residual current belongs to the natural leakage current under non-fault conditions or the residual current under fault conditions. When the residual current value increases, it is impossible to distinguish whether it is an increase in residual current under fault conditions or an increase in natural leakage current under non-fault conditions. Therefore, it is impossible to accurately track the trend of insulation changes and provide early warnings.

[0011] The residual current dynamic compensation amount of this technique is not a realistic parameter. The magnitude of the dynamic compensation amount cannot be accurately determined, and the comparison between the so-called residual current dynamic compensation amount and the residual current increment setpoint is meaningless.

[0012] Step 4: Due to the shortcomings of steps 1-3, the result of step 4 is also inaccurate.

[0013] 3. Method and System for Detecting Ground Leakage Current of Long-Distance Cables on the Secondary Side of AC Systems (Publication No.: CN112710931A). This technical method is applied to the detection of ground leakage current of long-distance cables on the secondary side of AC systems. The only criterion parameter used is the residual AC current, which is relatively singular and susceptible to misjudgment due to a single source of information, resulting in inaccurate alarm results. Without knowing environmental parameters and fault voltage values, it is impossible to determine the risk of electric shock from the fault voltage at the scene after a leakage fault occurs. It is also impossible to know whether the secondary circuit of the AC system can continue to operate with the fault under special circumstances to prevent secondary injuries caused by sudden power outages. A sudden loss of power to the secondary circuit of the AC system will cause the control circuit of the AC system to lose power, affecting the stability of the power system and causing widespread power outages. Therefore, graded protection actions should be implemented according to the actual situation at the fault site and the risk of a safety accident. The faulty circuit should be disconnected only after other backup emergency measures are implemented, rather than a one-size-fits-all tripping to disconnect the system power supply.

[0014] The initial "inherent residual current" (i.e., the natural leakage current under non-fault conditions) measured in advance during the construction and acceptance phase of Step 1 will change with the decline of insulation performance and changes in environmental conditions, load size, and equipment status. Therefore, the "inherent residual current" is not "inherent" and unchanging, and the initial value measured in advance has no practical significance.

[0015] The residual current detected in step 2 reflects the total residual current value of the entire long-distance cable, including natural leakage current and fault residual current. The detected residual current value at the end is the total residual current value of the cable at the end, including natural leakage current and fault residual current.

[0016] The residual current compensation in step 3 is essentially the natural leakage current value under non-fault conditions. However, for AC power distribution systems, when the residual current sensor detects residual current, it cannot distinguish whether the residual current belongs to the natural leakage current under non-fault conditions or the residual current under fault conditions. When the residual current value increases, it is impossible to distinguish whether the increase is due to the increase in residual current under fault conditions or the increase in natural leakage current under non-fault conditions. Therefore, it is impossible to accurately track the trend of insulation changes and provide early warnings.

[0017] Step 3 of this technical method compensates for the residual current based on the initial "inherent residual current" from step 1, but this does not reflect the actual situation, and the compensation result is meaningless. The so-called dynamic compensation amount of the residual current is a parameter that does not conform to reality. The magnitude of the dynamic compensation amount cannot be accurately determined, and the comparison result between the so-called dynamic compensation amount of the residual current and the incremental set value of the residual current is meaningless.

[0018] Step 4: Due to the shortcomings of steps 1-3, the result of step 4 is also inaccurate. Summary of the Invention

[0019] The purpose of this invention is to provide a method for monitoring and alarming the rate of change of residual current increment in an outdoor AC power distribution system.

[0020] The objective of this invention is achieved through the following technical solution: a method for monitoring and alarming the rate of change of residual current in an outdoor AC power distribution system, comprising the following steps:

[0021] S1. Install residual current sensor RCT, working current sensor CT, equipment enclosure fault voltage sensor RVT, ambient temperature sensor TT, ambient humidity sensor HT, water immersion sensor WT, and information sampling detector in the outdoor distribution box.

[0022] The information sampling detector collects the real-time values ​​of residual current I0, operating current I1, operating voltage U1, enclosure fault voltage U0, temperature T0, humidity H0, and water immersion switch quantity W0 of each AC power distribution circuit in the outdoor power distribution box at sampling time intervals; and stores the collected real-time data in list SL according to the storage data structure.

[0023] S2. The information sampling detector filters and classifies the real-time absolute values ​​of the sampled data, and further determines the degree of danger of different real-time values ​​by combining multi-dimensional information. It classifies and processes real-time abnormal data values ​​of different levels and stores them in storage lists of different danger levels.

[0024] S3. Process the real-time abnormal data in the storage list of different hazard levels, determine whether the abnormal data of the hazard level is continuous abnormal data in time. If continuous abnormal data is found, it is preliminarily determined that a hazard level has occurred, issue a hazard alarm broadcast, and send the abnormal data to the monitoring alarm and control management platform server through the communication module CM for further processing.

[0025] S4. Real-time alarm broadcast processing: Classify and process continuous abnormal hazard alarm broadcasts according to the hazard level.

[0026] S5. The monitoring, alarm, and control management platform server receives data from the information sampling detectors and stores it according to the time in the data structure;

[0027] S6. The monitoring, alarm and control management platform server calculates the rate of change of residual current sudden change increment, compares the rate of change of residual current sudden change increment with the corresponding early warning and alarm thresholds of the rate of change of sudden change increment, and issues an early warning or alarm broadcast of the rate of change of sudden change increment when it exceeds the corresponding threshold, and waits for execution feedback.

[0028] S7. The monitoring alarm and control management platform server performs residual current sudden change rate of change exceeding limit alarm broadcast processing. After the program is completed, it sends a signal to step S6 that the broadcast processing subroutine has been completed.

[0029] S8. The monitoring, alarm and control management platform server calculates the incremental change rate of residual current, processes the incremental change rate value and combines it with multi-dimensional environmental information to further determine the degree of insulation damage and predict the time of complete damage, and issues an early warning signal. At the same time, it controls the opening and closing of the circuit breaker QF in the outdoor distribution box based on the incremental change rate value and multi-dimensional environmental information.

[0030] Compared with the prior art, the advantages of the present invention are as follows:

[0031] 1. By dynamically tracking the short-term trend of residual current changes through the residual current mutation increment rate parameter, the system can identify the sharp increase in residual current caused by severe grounding faults such as sudden short circuits and perform rapid protection actions.

[0032] 2. The long-term trend of residual current variation is dynamically tracked by the residual current gradual increment rate parameter. This identifies slow increases in residual current caused by factors such as gradual aging of the insulation layer, allowing for early detection of potential leakage faults and providing early warnings. This enables maintenance personnel to conduct planned repairs and avoids secondary damage and other losses caused by sudden power outages after a fault occurs.

[0033] 3. Employ a multi-dimensional alarm mechanism: In addition to the residual current increment change rate parameter, this technical method also combines parameters such as the absolute value of residual current, ambient temperature and humidity, water immersion signal, and fault voltage value for comprehensive judgment, thereby improving the accuracy and reliability of the alarm.

[0034] 4. For sites where leakage faults occur, conduct an electric shock safety risk classification assessment by combining multi-dimensional environmental and electrical parameters to determine whether it is possible to continue working with the fault temporarily to avoid secondary injuries caused by sudden power outages. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the overall framework of the present invention.

[0036] Figure 2 This is a schematic diagram of the data acquisition and storage data structure in step S1 of the present invention.

[0037] Figure 3 This is a flowchart of step S1 of the present invention.

[0038] Figure 4 This is a flowchart of step S2 of the present invention.

[0039] Figure 5 yes Figure 4 A diagram illustrating the specific steps involved in initializing data filtering in China.

[0040] Figure 6 This is a flowchart of step S3 of the present invention.

[0041] Figure 7 This is a flowchart of step S4 of the present invention.

[0042] Figure 8 This is a flowchart of step S5 of the present invention.

[0043] Figure 9 This is a flowchart of step S6 of the present invention.

[0044] Figure 10 yes Figure 9 A schematic diagram illustrating the specific steps for initializing the calculation of the rate of change of the sudden change in residual current.

[0045] Figure 11 This is a flowchart of step S7 of the present invention.

[0046] Figure 12 This is a flowchart of step S8 of the present invention. Detailed Implementation

[0047] The present invention will now be described in detail with reference to the accompanying drawings and embodiments:

[0048] like Figure 1-12 The diagram shown is an embodiment of an alarm method for monitoring the rate of change of residual current in an outdoor AC power distribution system provided by the present invention.

[0049] The incremental residual current change rate monitoring alarm is a technical method for dynamically monitoring the change in residual current per unit time in AC electrical circuits. By continuously tracking the trend of residual current change, the system automatically issues an alarm signal when the incremental change rate of residual current exceeds a preset threshold. Unlike traditional static threshold alarm methods, incremental residual current change rate monitoring focuses more on the rate of change of residual current, rather than simply whether its absolute value exceeds a fixed threshold.

[0050] The core value of incremental residual current change rate monitoring and alarm function lies in dynamically capturing abnormal change trends of residual current (rather than just monitoring static thresholds), which can detect potential faults such as line insulation aging and local leakage earlier. Therefore, it can be widely used in fields with high electrical safety requirements, complex lines, or serious fault consequences.

[0051] To address issues such as natural aging of cable insulation, insulation damage caused during construction and wiring, or damage caused by rodents and ants, incremental change rate monitoring can detect the slow upward trend of residual current (e.g., gradually increasing from 10mA to 30mA). It can trigger an alarm before reaching the traditional static threshold (e.g., 50mA), thus enabling planned maintenance and avoiding secondary damage or other economic losses and safety accidents caused by sudden power outages.

[0052] The application scenarios of incremental residual current change rate monitoring and alarm function essentially cover all areas that need to detect leakage trends in advance and prevent the fault from escalating. Its core advantage is that it makes up for the lag of traditional static threshold monitoring through "dynamic incremental change rate analysis", and is especially suitable for complex, high-risk or electrical environments with high requirements for power supply reliability.

[0053] In outdoor AC power distribution systems, the basic working principle of incremental residual current rate of change monitoring is to calculate the increment and rate of change of the residual current by comparing the residual current values ​​at different time points, as shown in (Equations A.1) to (Equations A.2):

[0054] (Equation A.1)

[0055] (Equation A.2)

[0056] In the formula:

[0057]

[0058] When the rate of change of the residual current increment Exceeding the set threshold for incremental change rate ( When the residual current begins to deteriorate but has not yet reached the traditional static threshold, an alarm mechanism is triggered. This method can detect minute changes in the residual current and provide early warning when the insulation performance begins to deteriorate but has not yet reached the traditional static threshold, effectively preventing electric shock accidents. It can also shield the effects of natural leakage current.

[0059] In outdoor AC power distribution scenarios, incremental residual current rate of change monitoring and alarm functions have specific technical parameters:

[0060] The types of residual current increment include:

[0061] "Sudden change rate" (such as a sharp increase in residual current caused by a sudden short circuit in the line).

[0062] "Gradually changing incremental rate of change" (such as the slow increase in residual current caused by the gradual aging of the insulation layer).

[0063] The residual current increment rate monitoring in outdoor AC power distribution systems should be capable of detecting both types of increment rate changes.

[0064] Residual current monitoring range: Incremental residual current monitoring in outdoor AC power distribution scenarios typically ranges from 1mA to 30A, covering the full range of monitoring needs from minor insulation defects to severe leakage faults.

[0065] Alarm response time:

[0066] The system should issue an alarm signal within 30 seconds for the rate of change of the mutation increment;

[0067] For slowly changing incremental rates of change, the system should be able to capture the incremental trend and trigger an alarm within the set warning time window (such as 1 hour, 4 hours, etc.).

[0068] Alarm threshold setting:

[0069] For the rate of change of mutation increment, the alarm threshold is usually set to 5-15 mA / s;

[0070] For slowly varying incremental rates of change, the alarm threshold is typically set to 1-5 mA / h;

[0071] The specific values ​​need to be adjusted based on the characteristics of outdoor electrical lines and historical data.

[0072] Multi-dimensional alarm mechanism: In addition to the residual current increment, the system can also combine parameters such as the absolute value of the residual current, the operating current, the operating voltage, the ambient temperature and humidity, the fault voltage value, and the water immersion signal to make a comprehensive judgment, thereby improving the accuracy and reliability of the alarm.

[0073] The system of this method consists of an outdoor distribution box (cabinet) CB, a distribution circuit breaker QF inside the distribution box (cabinet), a residual current sensor RCT, a working current sensor CT, an equipment enclosure fault voltage sensor RVT, an ambient temperature sensor TT, an ambient humidity sensor HT, a water immersion sensor WT, an information sampling detector, a communication module, a monitoring alarm and control management platform server (including an application server, a network access server, a data storage server, etc.), and a user terminal management device Client.

[0074] The monitoring, alarm, and control management platform server of this system adopts a cloud computing platform.

[0075] The connection relationships of this system are as follows:

[0076] The coil of the residual current sensor RCT is connected to the power distribution circuit in the outdoor distribution box, and the output terminal of the residual current sensor RCT is connected to the input terminal of the information acquisition detector; the current coil of the working current sensor CT is connected to the power distribution circuit, and the output terminal of the working current sensor CT is connected to the input terminal of the information acquisition detector; the input terminal of the equipment enclosure fault voltage sensor RVT is connected to the enclosure of the outdoor distribution box, and the output terminal of the equipment enclosure fault voltage sensor RVT is connected to the input terminal of the information acquisition detector; the input terminal of the working voltage sensor VT is connected to the power distribution circuit, and the output terminal of the working voltage sensor VT is connected to the input terminal of the information acquisition detector; the output terminal of the ambient humidity sensor HT is connected to the input terminal of the information acquisition detector; the output terminal of the ambient temperature sensor TT is connected to the input terminal of the information acquisition detector; the output terminal of the water immersion signal sensor WT is connected to the input terminal of the information acquisition detector; the output control terminal of the information acquisition detector is connected to the automatic opening and closing control circuit of the circuit breaker QF; the communication port of the information acquisition detector is bidirectionally connected to the communication module CM; the communication port of the communication module CM is bidirectionally connected to the monitoring alarm and control management platform Server; the monitoring alarm and control management platform Server is bidirectionally connected to the user terminal management device Client.

[0077] The storage data structure is set as follows:

[0078] Each data entry contains 10 fields (D0~D9): D0: Sampling time t; D1: Real-time residual current value I0; D2: Real-time operating current value I1; D3: Real-time casing fault voltage value U0; D4: Real-time operating voltage value U1; D5: Real-time ambient temperature value T0; D6: Real-time ambient humidity value H0; D7: Real-time water immersion signal value W0; D8: Sampling address; D9: Data tag.

[0079] The present invention specifically includes the following steps:

[0080] Step S1

[0081] The information sampling detector collects the real-time values ​​of residual current I0, operating current I1, operating voltage U1, enclosure fault voltage U0, temperature T0, humidity H0, and water immersion switch quantity W0 of each AC power distribution circuit in the outdoor power distribution box at sampling time intervals; and stores the collected real-time data in list SL according to the storage data structure.

[0082] S1.1 Data Acquisition Subroutine Initialization:

[0083] S1.1.1 Perform network time synchronization to obtain the accurate sampling time t;

[0084] S1.1.2 Create a data sampling list SL, with a length of Len1;

[0085] S1.1.3 Create a data cache list TL, with a length of Len1;

[0086] S1.1.4 Set the data sampling interval G;

[0087] S1.1.5 Set the sample storage pointer P to the initial position of list SL (P=0);

[0088] S1.2 The information sampling detector collects the real-time values ​​of residual current I0(t), operating current I1(t), enclosure fault voltage U0(t), operating voltage U1(t), temperature T0(t), humidity H0(t), and water immersion switch quantity W0(t) of each AC power distribution circuit in the outdoor AC power distribution box at sampling time intervals.

[0089] S1.3 Store the collected real-time data into list SL according to the storage data structure;

[0090] S1.4 Move the storage pointer P down one position sequentially, P = P + 1, and determine whether the storage pointer has moved to the end of the storage list. If not, return to S1.2 to continue sampling and storing real-time data in sequence; if so, it means that the storage list SL is full, and transfer the data of SL to the cache list TL.

[0091] S1.5 Resets the storage pointer to the initial position of the storage list (P=0) and returns to S1.2 to continue sampling the stored data in chronological order.

[0092] Step S2

[0093] The Information Sampling Detector (RSD) filters and classifies the real-time absolute values ​​of the sampled data, and further determines the degree of danger of different real-time values ​​by combining multi-dimensional information. It classifies and processes real-time abnormal data values ​​of different levels and stores them in storage lists of different danger levels.

[0094] S2.1 Initialize the real-time absolute value filtering and classification processing program;

[0095] S2.1.1 Perform network time synchronization and frequency synchronization;

[0096] S2.1.2 Set the data storage lists respectively: Normal, I0-abnormal, I0U0-abnormal.

[0097] I0U0-abnormal, I0U0H0-abnormal, I0U0H0T0-abnormal, and I0U0W0-abnormal are used to classify and store various types of data.

[0098] S2.1.3 Set the absolute value threshold of residual current I0n, fault voltage threshold U0n, humidity threshold H0n, and temperature threshold T0n.

[0099] S2.1.4 Set the data read pointer R to point to the initial position of the data cache list (R=0).

[0100] S2.2 Read the D0~D7 fields of each row of data TL(R) in the data cache list in sequence.

[0101] S2.3 Compare the real-time absolute value of the residual current I0 with the threshold value of the residual current I0n: If I0 < I0n, no leakage has occurred, the system is operating normally, and other parameters can be ignored. Set the Label value of the D9 field of this data set TL(R) to 0; then store this data set TL(R) in the Normal data list. If I0 > I0n, it indicates that a leakage fault may have occurred, and proceed to the next step of comparing the real-time fault voltage value U0.

[0102] S2.4 Compare the real-time fault voltage value U0 with the fault voltage threshold U0n: If U0 < U0n, it indicates that no dangerous fault voltage has occurred, and the Label value of the D9 field of this data set TL(R) is set to 1; then, this data set TL(R) is stored in the I0-abnormal abnormal data list, and the abnormal data processing subroutine is entered to process the abnormal data. If U0 > U0n, it indicates that a leakage fault has occurred and a dangerous fault voltage has occurred, and the next step is to compare and process the real-time water immersion signal W0.

[0103] S2.5 Compare the real-time water immersion signal W0 to assess the impact of water immersion on the conduction of fault voltage U0. If W0=0, it indicates that although a leakage fault has occurred and a dangerous fault voltage has appeared, water immersion has not occurred, and the fault voltage only appears in a limited local area and has not yet been conducted through a large area of ​​accumulated water. Then proceed to step S2.6. If W0=1, it indicates that water immersion has occurred, and the fault voltage will be conducted through a large area of ​​accumulated water. At this time, the risk of electric shock to personnel is extremely high, then proceed to step S2.11.

[0104] S2.6 Process the real-time humidity data H0 to evaluate the impact of humidity H0 on the conduction of fault voltage U0. If H0 < H0n, it indicates that the humidity is low and will not affect the conduction of fault voltage, then proceed to S2.7. If H0 > H0n, it indicates that the humidity is high and may affect the conduction of fault voltage, but the conduction distance is limited, then proceed to S2.8.

[0105] S2.7. Set the Label value of the D9 field of the data TL(R) to 2, then store the data TL(R) into the I0U0-abnormal list, and simultaneously enter the abnormal data processing subroutine to process the abnormal data.

[0106] S2.8. Proceed to the next step of evaluating and processing the real-time temperature data T0. If T0 < T0n, it indicates that the ambient humidity is high but the ambient temperature is not high, then proceed to S2.9. If T0 > T0n, it indicates that both the ambient humidity and the ambient temperature are high, then proceed to S2.10.

[0107] S2.9 Set the Label value of the D9 field of the data TL(R) to 3; then store the data TL(R) in the I0U0H0-abnormal abnormal data list, and enter the abnormal data processing subroutine to process the abnormal data.

[0108] S2.10 Set the Label value of the D9 field of the data TL(R) to 4; then store the data TL(R) in the I0U0H0T0-abnormal abnormal data list, and enter the abnormal data processing subroutine to process the abnormal data.

[0109] S2.11 Set the Label value of the D9 field of the data TL(R) to 5; then store the data TL(R) in the I0U0W0-abnormal abnormal data list, and enter the abnormal data processing subroutine to process the abnormal data.

[0110] S2.12 Move the data read pointer down one position sequentially (R=R+1). If the data pointer does not point to the end of the data cache list TL, continue reading the next set of data and repeat the above operations (2)~(5). If the data pointer R has exceeded the last storage position of TL, then point the data read pointer back to the initial position (R=0) and perform a new round of data processing. The speed of data processing is synchronized with the speed of data sampling and updating.

[0111] Step 3:

[0112] The system processes real-time abnormal data in storage lists of different hazard levels, determines whether the abnormal data of a certain hazard level is continuous abnormal data over time, and if continuous abnormal data is found, it preliminarily determines that a hazard of that hazard level has occurred, issues a hazard alarm broadcast (Danger), and waits for the feedback signal that the alarm broadcast (Danger) processing subroutine has completed execution.

[0113] Step 4:

[0114] Real-time alarm broadcast (Danger) processing, and classification and processing of continuous abnormal hazard alarm broadcast (Danger) according to hazard level:

[0115] S4.1 If Danger=0, the values ​​of data I0, U0, T0, H0, and W0 will be displayed on the detector screen at the site. The detector indicator lights will flash green at 0.5s intervals, the buzzer will be turned off, and the system will be operating normally. At the same time, the data in the Normal list will be sent to the monitoring alarm and control management platform server via the communication module CM for further processing; otherwise, proceed to step S4.2.

[0116] S4.2 If Danger=1, the values ​​of data I0, U0, T0, H0, and W0 will be displayed on the detector screen at the site. The detector indicator light will flash white light at 2-second intervals, and the buzzer will sound an alarm at 2-second intervals. At the same time, the data in the I0-abormal list will be sent to the monitoring alarm and control management platform server through the communication module CM for further processing; otherwise, proceed to step S4.3.

[0117] S4.3 If Danger=2, the values ​​of data I0, U0, T0, H0, and W0 will be displayed on the detector screen at the site. The detector indicator light will flash blue at 1.5-second intervals, and the buzzer will sound an alarm at 1.5-second intervals. At the same time, the data in the I0U0-abormal list will be sent to the monitoring alarm and control management platform server via the communication module CM for further processing; otherwise, proceed to step 4.4.

[0118] S4.4 If Danger=3, the values ​​of data I0, U0, T0, H0, and W0 will be displayed on the detector screen at the site. The detector indicator light will flash yellow at 1-second intervals, and the buzzer will sound an alarm at 1-second intervals. At the same time, the data in the I0U0H0-abormal list will be sent to the monitoring alarm and control management platform server via the communication module CM for further processing; otherwise, proceed to step 4.5.

[0119] S4.5 If Danger=4, the values ​​of data I0, U0, T0, H0, and W0 will be displayed on the detector screen at the site. The detector indicator lights will flash orange at 0.5-second intervals, and the buzzer will sound an alarm at 0.5-second intervals. At the same time, the data in the I0U0H0T0-abormal list will be sent to the monitoring alarm and control management platform server via the communication module CM for further processing; otherwise, proceed to step 4.6.

[0120] S4.6 If Danger=5, the values ​​of data I0, U0, T0, H0, and W0 will be displayed on the detector screen at the site. The detector indicator lights will flash white lights at 0.25s intervals, and the buzzer will sound an alarm at 0.25s intervals. At the same time, the data in the I0U0W0-abormal list will be sent to the monitoring alarm and control management platform server via the communication module CM for further processing; otherwise, proceed to step 4.7.

[0121] S4.7 If the value of Danger is not in the range of 0~5, the program will report an error and reinitialize Danger=0; proceed to step S4.8.

[0122] S4.8 Send a signal to step 3 indicating that the alarm broadcast has been completed.

[0123] Step 5:

[0124] The monitoring alarm and control management platform server receives data from the information sampling detector (RSD) and stores it according to the time in the data structure.

[0125] Step 6:

[0126] The monitoring alarm and control management platform server calculates the rate of change of residual current sudden change increment, compares the rate of change of residual current sudden change increment with the corresponding sudden change increment warning and alarm threshold, and when it exceeds the corresponding threshold, issues a sudden change increment over-limit warning or alarm broadcast, and waits for execution feedback.

[0127] S6.1 Initialization of the calculation of the rate of change of residual current sudden increment;

[0128] S6.1.1 Perform network time synchronization, ensuring same frequency; the data processing speed is synchronized with the data sampling and update speed;

[0129] S6.1.2 Set the data for short time intervals Gs in seconds;

[0130] S6.1.3 Set the data read pointer Point1 to the initial data storage location, Point1=0;

[0131] S6.1.4 Set the data read pointer Point2 to the data storage location, Point2 = Point1 + Gs;

[0132] S6.1.5 Set the alarm threshold I1Δn1 and the warning threshold I1Δn2 for the rate of change of residual current sudden change, and I1Δn1 > I1Δn2;

[0133] S6.2 Read the first data value I0(t1) calculated from the residual current increment of the data storage server at the position pointed to by Point1;

[0134] S6.3 Read the second data value I0(t2) calculated from the residual current increment of the data storage server, based on the position pointed to by Point2;

[0135] S6.4 Calculate the rate of change of residual current sudden increment using the calculation formula:

[0136] I1Δ(t)=[I0(t2)-I0(t1)] / (t2-t1);

[0137] S6.5 Compare I1Δ(t) with the alarm threshold I1Δn1 for the rate of change of residual current sudden change, and execute different steps according to the comparison result; if I1Δ(t) > I1Δn1, execute step S6.7; if I1Δ(t) < I1Δn1, execute step S6.6.

[0138] S6.6 Compare I1Δ(t) with the warning threshold I1Δn2 of the rate of change of the sudden change in residual current, and perform different steps according to the comparison result; if I1Δ(t)>I1Δn2, perform step S6.7; if I1Δ(t)<I1Δn2, perform step S6.8.

[0139] S6.7 Issue an alarm broadcast and wait for execution feedback; if no feedback is received, continue to wait for feedback signal; if feedback signal is received, execute S6.8.

[0140] S6.8 Shift the read pointer Point1 down by one position, Point1 = Point1 + 1, and shift the read pointer Point2 down by Gs positions, Point2 = Point1 + Gs;

[0141] S6.9 Compare the position pointed to by Point2 with the current maximum storage length, and perform different steps according to the comparison result; if the position pointed to by Point2 does not exceed the current maximum storage length, return and repeat S6.2~S6.9; if the position pointed to by Point2 exceeds the current maximum storage length, execute S6.10.

[0142] S6.10 Reset the data read pointer Point1 to the initial data storage location, Point1=0; set the data read pointer Point2 to the data storage location, Point2=Point1+Gs, and return to repeat S6.2~S6.9.

[0143] Step 7:

[0144] The monitoring, alarm, and control management platform server processes the alarm broadcast (Label) for excessive residual current change rate. After the program completes execution, it sends a signal indicating that the broadcast (Label) processing subroutine has finished executing to step 6.

[0145] S7.1 When a residual current sudden change rate exceeding the limit alarm broadcast (Label) is detected, read the label value of the data pointed to by Point1 and Point2, and execute different steps according to the value of Label. If Label=0, execute S7.2; if Label=1, execute S7.3; if Label=2, execute S7.4; if Label=3, execute S7.5; if Label=4, execute S7.6; if Label=5, execute S7.7; otherwise, execute S7.8.

[0146] S7.2 The monitoring alarm and control management platform displays the values ​​of I1Δ(t), I0, U0, H0, T0, and W0. The monitoring platform displays "No leakage current, system is operating normally" and sends control commands to the detector to control the circuit breaker to close and keep the circuit connected.

[0147] S7.3 The monitoring alarm and control management platform displays the values ​​of I1Δ(t), I0, U0, H0, T0, and W0. The monitoring platform displays "Leakage has occurred, but no dangerous voltage has appeared," and the monitoring alarm and control management platform switches to manual control mode by the management personnel.

[0148] S7.4 The monitoring alarm and control management platform displays the values ​​of I1Δ(t), I0, U0, H0, T0, and W0. The monitoring platform displays "Leakage has occurred, dangerous voltage has appeared, no water immersion has occurred, and the ambient humidity is not high." The monitoring alarm and control management platform then switches to manual control mode by the management personnel.

[0149] S7.5 The monitoring alarm and control management platform displays the values ​​of I1Δ(t), I0, U0, H0, T0, and W0. The monitoring platform displays "Leakage has occurred, dangerous voltage has appeared, no water immersion has occurred, ambient humidity is high, ambient temperature is not high", and the monitoring alarm and control management platform switches to manual control mode by the management personnel.

[0150] S7.6 The monitoring alarm and control management platform displays the values ​​of I1Δ(t), I0, U0, H0, T0, and W0. The monitoring platform displays "Leakage has occurred, dangerous voltage has appeared, water immersion has not occurred, ambient humidity is high, ambient temperature is high", and the monitoring alarm and control management platform switches to manual control mode by the management personnel.

[0151] S7.7 displays the values ​​of I1Δ(t), I0, U0, H0, T0, and W0 on the monitoring, alarm, and control management platform. The monitoring platform displays "Leakage has occurred, dangerous voltage has appeared, water immersion has occurred," and the monitoring, alarm, and control management platform issues a control command to control the circuit breaker QF to open and disconnect the circuit.

[0152] S7.8 If the value of Label is not in the range of 0~5, the program will report an error and reinitialize Label=0; proceed to step S7.9.

[0153] S7.9 Sends a Label broadcast command to step A6.7 to confirm execution.

[0154] Step 8:

[0155] The monitoring, alarm, and control management platform server calculates the incremental change rate of residual current, processes the incremental change rate value, and combines it with multi-dimensional environmental information to further determine the degree of insulation damage and predict the time to complete failure, issuing an early warning signal. Simultaneously, it controls the opening and closing of the circuit breaker QF based on the incremental change rate value and multi-dimensional environmental information.

[0156] S8.1 Initialization of residual current gradual increment rate of change calculation;

[0157] S8.1.1 performs network time synchronization, ensuring synchronization with the same frequency; the speed of data processing is synchronized with the speed of data sampling and updating.

[0158] S8.1.2 Set the data with a time interval of Gh for hours / days / months / years. Gh is set by the administrator in the program operation interface.

[0159] S8.1.3 Set the data read pointer Point3 to the initial data storage location (Point3=0);

[0160] S8.1.4 Set the data read pointer Point4 to the data storage location (Point4 = Point1 + Gh);

[0161] S8.1.5 Set the alarm threshold I2Δn1 and the warning threshold I2Δn2 (I2Δn1>I2Δn2) for the residual current gradual change rate of change;

[0162] S8.2 Read the first data value I0(t1) calculated by the residual current increment of the data storage server at the position pointed to by Point3;

[0163] S8.3 Read the second data value I0(t2) calculated from the residual current increment of the data storage server, based on the position pointed to by Point4;

[0164] S8.4 Calculate the rate of change of the residual current incremental change according to the calculation formula:

[0165] I2Δ(t)=[I0(t2)-I0(t1)] / (t2-t1);

[0166] S8.5 compares I2Δ(t) with the residual current gradual increment rate of change alarm threshold I2Δn1, and performs different steps based on the comparison result. If I2Δ(t) > I2Δn1, proceed to step S8.7; if I2Δ(t) < I2Δn1, proceed to step S8.6.

[0167] S8.6 compares I2Δ(t) with the warning threshold I2Δn2 of the residual current's gradual incremental change rate, and performs different steps based on the comparison result. If I2Δ(t) > I2Δn2, proceed to step S8.8; if I2Δ(t) < I2Δn2, proceed to step S8.9.

[0168] The S8.7 monitoring, alarm, and control management platform displays "Leakage has occurred; the insulation of the power distribution cable has failed and needs replacement. Please perform timely maintenance" and shows the fault address, then sends a maintenance work order. Proceed to S8.9.

[0169] The S8.8 monitoring alarm and control management platform displays "The insulation of the power distribution cable is about to fail, please maintain it in time" and displays the maintenance address. Then proceed to S8.9.

[0170] S8.9 Shift the read pointer Point1 down by one bit (Point3 = Point3 + 1), and shift the read pointer Point4 down by Gh bits (Point4 = Point3 + Gh).

[0171] S8.10 Compare the position pointed to by Point4 with the current maximum storage length, and perform different steps based on the comparison result. If the position pointed to by Point4 does not exceed the current maximum storage length, return and repeat S8.2~S8.9.

[0172] If the location pointed to by Point4 exceeds the current maximum storage length, then execute S8.10.

[0173] S8.10 Reset the data read pointer Point3 to the initial data storage location (Point3=0); set the data read pointer Point4 to the data storage location (Point4=Point1+Gh), and return to repeat S8.2~S8.9.

Claims

1. A method for monitoring and alarming the rate of change of residual current increment in an outdoor AC power distribution system, characterized in that, Includes the following steps: S1. Install residual current sensor RCT, working current sensor CT, equipment enclosure fault voltage sensor RVT, ambient temperature sensor TT, ambient humidity sensor HT, water immersion sensor WT, and information sampling detector in the outdoor distribution box. The information sampling detector collects the real-time values ​​of residual current I0, operating current I1, operating voltage U1, enclosure fault voltage U0, temperature T0, humidity H0, and water immersion switch quantity W0 of each AC power distribution circuit in the outdoor power distribution box at sampling time intervals; and stores the collected real-time data in list SL according to the storage data structure. S2. The information sampling detector filters and classifies the real-time absolute values ​​of the sampled data, and further determines the degree of danger of different real-time values ​​by combining multi-dimensional information. It classifies and processes real-time abnormal data values ​​of different levels and stores them in storage lists of different danger levels. S3. Process the real-time abnormal data in the storage list of different hazard levels, determine whether the abnormal data of the hazard level is continuous abnormal data in time. If continuous abnormal data is found, it is preliminarily determined that a hazard level has occurred, issue a hazard alarm broadcast, and send the abnormal data to the monitoring alarm and control management platform server through the communication module CM for further processing. S4. Real-time alarm broadcast processing: Classify and process continuous abnormal hazard alarm broadcasts according to the hazard level. S5. The monitoring, alarm, and control management platform server receives data from the information sampling detectors and stores it according to the time in the data structure; S6. The monitoring, alarm and control management platform server calculates the rate of change of residual current sudden change increment, compares the rate of change of residual current sudden change increment with the corresponding early warning and alarm thresholds of the rate of change of sudden change increment, and issues an early warning or alarm broadcast of the rate of change of sudden change increment when it exceeds the corresponding threshold, and waits for execution feedback. S7. The monitoring alarm and control management platform server performs residual current sudden change rate of change exceeding limit alarm broadcast processing. After the program is completed, it sends a signal to step S6 that the broadcast processing subroutine has been completed. S8. The monitoring, alarm and control management platform server calculates the incremental change rate of residual current, processes the incremental change rate value and combines it with multi-dimensional environmental information to further determine the degree of insulation damage and predict the time of complete damage, and issues an early warning signal. At the same time, it controls the opening and closing of the circuit breaker QF in the outdoor distribution box based on the incremental change rate value and multi-dimensional environmental information.

2. The method for monitoring and alarming the rate of change of residual current in an outdoor AC power distribution system according to claim 1, characterized in that: The coil of the residual current sensor RCT is connected to the power distribution circuit in the outdoor distribution box, and the output terminal of the residual current sensor RCT is connected to the input terminal of the information acquisition detector; the current coil of the working current sensor CT is connected to the power distribution circuit, and the output terminal of the working current sensor CT is connected to the input terminal of the information acquisition detector; the input terminal of the equipment enclosure fault voltage sensor RVT is connected to the enclosure of the outdoor distribution box, and the output terminal of the equipment enclosure fault voltage sensor RVT is connected to the input terminal of the information acquisition detector; the input terminal of the working voltage sensor VT is connected to the power distribution circuit, and the output terminal of the working voltage sensor VT is connected to the input terminal of the information acquisition detector; the output terminal of the ambient humidity sensor HT is connected to the input terminal of the information acquisition detector; the output terminal of the ambient temperature sensor TT is connected to the input terminal of the information acquisition detector; the output terminal of the water immersion signal sensor WT is connected to the input terminal of the information acquisition detector; the output control terminal of the information acquisition detector is connected to the automatic opening and closing control circuit of the circuit breaker QF; the communication port of the information acquisition detector is bidirectionally connected to the communication module CM; the communication port of the communication module CM is bidirectionally connected to the monitoring alarm and control management platform Server; the monitoring alarm and control management platform Server is bidirectionally connected to the user terminal management device Client.

3. The method for monitoring and alarming the rate of change of residual current in an outdoor AC power distribution system according to claim 2, characterized in that: The data in list SL consists of 10 fields: D0: sampling time t; D1: real-time value of residual current I0; D2: Real-time operating current value I1; D3: Real-time value of casing fault voltage U0; D4: Real-time value of operating voltage U1; D5: Real-time value of ambient temperature T0; D6: Real-time value of ambient humidity H0; D7: Real-time value of water immersion signal W0; D8: Sampling address; D9: Data tag.

4. The method for monitoring and alarming the rate of change of residual current in an outdoor AC power distribution system according to claim 3, wherein the specific process of step S1 is as follows: S1.1 Data Acquisition Subroutine Initialization: S1.1.1 Perform network time synchronization to obtain the accurate sampling time t; S1.1.2 Create a data sampling list SL, with a length of Len1; S1.1.3 Create a data cache list TL, with a length of Len1; S1.1.4 Set the data sampling interval G; S1.1.5 Set the sample storage pointer P to the initial position of list SL; S1.2 The information sampling detector collects the real-time values ​​of residual current I0, operating current I1, enclosure fault voltage U0, operating voltage U1, temperature T0, humidity H0, and water immersion switch quantity W0 of each AC power distribution circuit in the outdoor AC power distribution box at sampling time intervals. S1.3 Store the collected real-time data into list SL according to the storage data structure; S1.4 Move the storage pointer P down one position sequentially, P = P + 1, and determine whether the storage pointer has moved to the end of the storage list. If not, return to S1.2 to continue sampling and storing real-time data in sequence; if so, it means that the storage list SL is full, and transfer the data of SL to the cache list TL. S1.5 Resets the storage pointer to the initial position of the storage list and returns to S1.2 to continue sampling the stored data in chronological order.

5. The method for monitoring and alarming the rate of change of residual current in an outdoor AC power distribution system according to claim 3, characterized in that, The specific process of step S2 is as follows: S2.1 Initialize the real-time absolute value filtering and classification processing program; S2.1.1 Perform network time synchronization and frequency synchronization; S2.1.2 Set the data storage lists respectively: Normal, I0-abnormal, I0U0-abnormal. I0U0-abnormal, I0U0H0-abnormal, I0U0H0T0-abnormal, and I0U0W0-abnormal are used to classify and store various types of data. S2.1.3 Set the absolute value threshold of residual current I0n, fault voltage threshold U0n, humidity threshold H0n, and temperature threshold T0n; S2.1.4 Set the data read pointer R to point to the initial position of the data cache list TL; S2.2 Read the D0~D7 fields of each row of data TL in the data cache list in sequence; S2.3 Compare the real-time absolute value of the residual current I0 with the threshold value of the residual current I0n: If I0 < I0n, no leakage has occurred, the system is operating normally, and other parameters are ignored. Set the Label value of the D9 field of this data set TL to 0; then store this data set TL in the Normal normal data list; if I0 > I0n, it indicates that a leakage fault may have occurred, and proceed to the next step of comparing the real-time fault voltage value U0. S2.4 Compare the real-time fault voltage value U0 with the fault voltage threshold U0n: If U0 < U0n, it indicates that no dangerous fault voltage has occurred, and set the Label value of the D9 field of this data set TL to 1; Then, the data TL is stored in the I0-abnormal abnormal data list, and the abnormal data processing subroutine is entered to process the abnormal data. If U0 > U0n, it indicates that a leakage fault has occurred and a dangerous fault voltage has appeared, and proceed to the next step of comparing and processing the real-time water immersion signal W0. S2.5 Compare the real-time water immersion signal W0 to assess the impact of water immersion on the conduction of fault voltage U0. If W0=0, it indicates that although a leakage fault has occurred and a dangerous fault voltage has appeared, water immersion has not occurred, and the fault voltage only appears in a limited local area and has not yet been conducted through the water over a large area. Then proceed to step S2.

6. If W0=1, it indicates that water immersion has occurred, and the fault voltage will be conducted through the water over a large area. At this time, the risk of electric shock to human safety is extremely high. Then proceed to step S2.

11. S2.6 Process the real-time humidity data H0 and evaluate the impact of humidity H0 on the conduction of fault voltage U0. If H0 < H0n, it indicates that the humidity is low and will not affect the conduction of fault voltage, then proceed to S2.7; if H0 > H0n, it indicates that the humidity is high and may affect the conduction of fault voltage, but the conduction distance is limited, then proceed to S2.

8. S2.

7. Set the Label value of the D9 field of the data TL to 2, then store the data TL in the I0U0-abnormal list, and enter the abnormal data processing subroutine to process abnormal data. S2.

8. Proceed to the next step of evaluating and processing the real-time temperature data T0. If T0 < T0n, it indicates that the ambient humidity is high but the ambient temperature is not high, then proceed to S2.9; if T0 > T0n, it indicates that the ambient humidity is high and the ambient temperature is also high, then proceed to S2.

10. S2.9 sets the Label value of the D9 field of the data TL to 3; then stores the data TL in the I0U0H0-abnormal abnormal data list, and enters the abnormal data processing subroutine to process the abnormal data. S2.10 sets the Label value of the D9 field of the data TL to 4; then stores the data TL in the I0U0H0T0-abnormal abnormal data list, and enters the abnormal data processing subroutine to process the abnormal data. S2.11 Sets the Label value of the D9 field of the data TL to 5; then stores the data TL in the I0U0W0-abnormal abnormal data list, and enters the abnormal data processing subroutine to process the abnormal data. S2.12 Move the data read pointer down one position sequentially. If the data pointer does not point to the end of the data cache list TL, continue reading the next set of data and repeat the above operations S2.2~S2.

5. If the data pointer R has exceeded the last storage position of the data TL, the data read pointer is reset to the initial position and a new round of data processing is performed. The speed of data processing is synchronized with the speed of data sampling and updating.

6. The method for monitoring and alarming the rate of change of residual current in an outdoor AC power distribution system according to claim 5, characterized in that, The specific process of step S6 is as follows: S6.1 Initialization of the calculation of the rate of change of residual current sudden increment; S6.1.1 Perform network time synchronization, ensuring same frequency; the data processing speed is synchronized with the data sampling and update speed; S6.1.2 Set the data for short time intervals Gs in seconds; S6.1.3 Set the data read pointer Point1 to the initial data storage location, Point1=0; S6.1.4 Set the data read pointer Point2 to the data storage location, Point2 = Point1 + Gs; S6.1.5 Set the alarm threshold I1Δn1 and the warning threshold I1Δn2 for the rate of change of residual current sudden change, and I1Δn1 > I1Δn2; S6.2 Read the first data value I0(t1) calculated from the residual current increment of the data storage server at the position pointed to by Point1; S6.3 Read the second data value I0(t2) calculated from the residual current increment of the data storage server, based on the position pointed to by Point2; S6.4 Calculate the rate of change of residual current sudden increment using the calculation formula: I1Δ(t)=[I0(t2)-I0(t1)] / (t2-t1); S6.5 Compare I1Δ(t) with the alarm threshold I1Δn1 for the rate of change of residual current sudden change, and execute different steps according to the comparison result; if I1Δ(t) > I1Δn1, execute step S6.7; if I1Δ(t) < I1Δn1, execute step S6.

6. S6.6 Compare I1Δ(t) with the warning threshold I1Δn2 of the rate of change of the sudden change in residual current, and perform different steps according to the comparison result; if I1Δ(t)>I1Δn2, perform step S6.7; if I1Δ(t)<I1Δn2, perform step S6.

8. S6.7 Issue an alarm broadcast and wait for execution feedback; if no feedback is received, continue to wait for feedback signal; if feedback signal is received, execute S6.

8. S6.8 Shift the read pointer Point1 down by one position, Point1 = Point1 + 1, and shift the read pointer Point2 down by Gs positions, Point2 = Point1 + Gs; S6.9 Compare the position pointed to by Point2 with the current maximum storage length, and perform different steps according to the comparison result; if the position pointed to by Point2 does not exceed the current maximum storage length, return and repeat S6.2~S6.9; if the position pointed to by Point2 exceeds the current maximum storage length, execute S6.

10. S6.10 Reset the data read pointer Point1 to the initial data storage location, Point1=0; set the data read pointer Point2 to the data storage location, Point2=Point1+Gs, and return to repeat S6.2~S6.

9.

7. The method for monitoring and alarming the rate of change of residual current in an outdoor AC power distribution system according to claim 6, characterized in that, The specific process of step S8 is as follows: S8.1 Initialization of residual current gradual increment rate of change calculation; S8.1.1 Perform network time synchronization, ensuring synchronization with the same frequency; the data processing speed is synchronized with the data sampling and update speed; S8.1.2 Set the data with a time interval of Gh for hours / days / months / years. Gh is set by the administrator in the program operation interface. S8.1.3 Set the data read pointer Point3 to the initial data storage location, Point3=0; S8.1.4 Set the data read pointer Point4 to the data storage location, Point4 = Point1 + Gh; S8.1.5 Set the alarm threshold I2Δn1 and the warning threshold I2Δn2 for the residual current slow change rate of change, and I2Δn1 > I2Δn2; S8.2 Read the first data value I0(t1) calculated by the residual current increment of the data storage server at the position pointed to by Point3; S8.3 Read the second data value I0(t2) calculated from the residual current increment of the data storage server, based on the position pointed to by Point4; S8.4 Calculate the rate of change of the residual current incremental change according to the calculation formula: I2Δ(t)=[I0(t2)-I0(t1)] / (t2-t1); S8.5 compares I2Δ(t) with the alarm threshold I2Δn1 for the slow incremental change rate of residual current, and performs different steps according to the comparison result; if I2Δ(t)>I2Δn1, execute step S8.7; if I2Δ(t)<I2Δn1, execute step S8.

6. S8.6 Compare I2Δ(t) with the warning threshold I2Δn2 of the slow incremental change rate of residual current, and perform different steps according to the comparison result; if I2Δ(t)>I2Δn2, execute step S8.8; if I2Δ(t)<I2Δn2, execute step S8.

9. The S8.7 monitoring alarm and control management platform displays "Leakage has occurred, the insulation of the power distribution cable has failed and needs to be replaced. Please maintain it in time" and displays the fault address. It then sends a maintenance work order and proceeds to S8.

9. The S8.8 monitoring alarm and control management platform displays "The insulation of the power distribution cable is about to fail, please maintain it in time" and displays the maintenance address. Proceed to S8.

9. S8.9 Shift the read pointer Point1 down by one position, Point3 = Point3 + 1, and shift the read pointer Point4 down by Gh positions, Point4 = Point3 + Gh; S8.10 Compare the position pointed to by Point4 with the current maximum storage length, and perform different steps according to the comparison result. If the position pointed to by Point4 does not exceed the current maximum storage length, return and repeat S8.2~S8.

9. If the location pointed to by Point4 exceeds the current maximum storage length, then execute S8.10; S8.11 Reset the data read pointer Point3 to the initial data storage location (Point3=0); set the data read pointer Point4 to the data storage location (Point4=Point1+Gh), and return to repeat S8.2~S8.9.

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