A power grid operation state trend analysis and prediction method

Abstract

This application belongs to the technical field of power grid operation and equipment status trend prediction methods, and particularly relates to a power grid operation status trend analysis and prediction method. It includes steps for implementing differential current value trend prediction, determining the necessity of differential current value trend prediction for longitudinal differential line protection, and executing differential current value trend prediction for longitudinal differential line protection. This power grid operation status trend prediction method fully utilizes the basic data from existing real-time power grid information data systems. By analyzing and predicting the simulated quantities of detected operation status, it quickly and accurately makes trend prediction analyses. Compared with the traditional manual on-site inspection mode, it has higher accuracy and efficiency, significantly improving the quality of inspection work. By analyzing the changing trends of relevant simulated quantities and risk prediction, potential defects can be detected in advance, improving operational reliability.

Description

Technical Field

[0001] This application belongs to the technical field of power grid operation and equipment status trend prediction methods, and particularly relates to a power grid operation status trend analysis and prediction method. Background Technology

[0002] Currently, secondary maintenance personnel primarily employ traditional monitoring, inspection, and scheduled checks. This approach fails to fully leverage the powerful self-checking capabilities and advanced application support of intelligent secondary equipment. A significant amount of basic data remains uncollected and its value cannot be fully extracted, hindering the implementation of advanced intelligent maintenance applications. This results in poor accuracy and quality in secondary maintenance work, low personnel efficiency, and persistently high maintenance costs. While remote automatic inspection technology based on real-time operational data exists, capable of periodically inspecting circuit breakers, hard and soft pressure plates, setpoints, indicator lights, differential current, light intensity, device temperature, and operating voltage, and outputting inspection anomaly alarms and reports, this inspection mode can only determine whether an anomaly has occurred. It cannot track, record, or analyze trends in relevant analog quantities during normal device operation to predict and warn of potential defects, thereby improving device reliability. Summary of the Invention

[0003] The purpose of this application is to provide a power grid operation status trend analysis and prediction method that can effectively acquire and predict the expected operating status of various equipment or projects at different stages of their operation, detect potential equipment problems early, and improve the reliability of equipment operation.

[0004] To achieve the above objectives, this application adopts the following technical solution.

[0005] A method for predicting the trend of power grid operating status includes steps for predicting the trend of differential current values, including:

[0006] Step 1: Used to predict the trend of differential current values ​​for longitudinal differential line protection, including A1 and A2;

[0007] A1. The necessity of predicting the trend of differential current value for longitudinal differential line protection.

[0008] Specifically, based on the detection data of high-voltage line protection devices, when the measured maximum secondary load current is <0.1In, no differential current trend analysis is performed; when the maximum differential current of any phase is <=0.02In, no differential current trend analysis is performed; In is the secondary rated current setting.

[0009] A2. Perform differential current value trend prediction for longitudinal differential line protection.

[0010] Specifically, when 0.02In < the maximum measured differential current of any phase <= 0.04In and shows an upward trend, a warning message about differential current in the prediction channel will be issued after a 90-second delay.

[0011] When 0.04In < the maximum measured differential current in any phase < 0.9Id and it shows an upward trend, a predicted differential current exceeding limit prompt message is reported after a 90s delay; Id is the fixed value of the differential protection operating current.

[0012] When the differential current in any phase is greater than 0.9Id, the protection device shall report a differential current exceeding limit alarm signal, and after a 10s delay and a 10s broadening, it reports an alarm for long-term differential current in the channel.

[0013] When 0.9Id < the differential current in any phase < Id and it shows an upward trend, a predicted longitudinal differential protection operation prompt message is reported after a 90s delay.

[0014] For a further improvement or preferred implementation of the aforementioned power grid operation state trend prediction method, during the process of performing the trend prediction of the differential current value of the longitudinal differential line protection in A2, when the differential current in any phase is greater than 0.9Id and the protection device shall report a differential current exceeding limit alarm signal, if the corresponding alarm signal is not detected within 90S, it gives that the device should report a differential current exceeding limit alarm but actually does not report the alarm.

[0015] For a further improvement or preferred implementation of the aforementioned power grid operation state trend prediction method, the so-called "showing an upward trend" specifically means that the average value of at least 3 consecutive 2-point sampling values continuously measured increases.

[0016] For a further improvement or preferred implementation of the aforementioned power grid operation state trend prediction method, the steps for realizing the trend prediction of the differential current value further include:

[0017] Step 2: For the trend prediction of the differential current value of the bus protection, including B1 and B2;

[0018] B1. Judge the necessity of the trend prediction of the differential current value of the bus protection

[0019] Specifically, based on the detection data of the bus protection device, when the maximum measured differential current in any phase <= 0.02In, no differential current trend analysis is performed; when the maximum measured differential current in any phase > 0.02In, differential current trend analysis is performed;

[0020] B2. Perform the trend prediction of the differential current value of the bus protection

[0021] Specifically, when 0.02In < the measured differential current in any phase <= 0.04In and it shows an upward trend, a predicted differential current prompt message is reported after a 90S delay;

[0022] When 0.04In < the maximum measured differential current in any phase < 0.15Ie, a prompt message indicating that there is differential current in the bus protection is reported; Ie is the rated secondary current on the high voltage side of the transformer;

[0023] When 0.15Ie < the measured differential current in any phase < Id and it shows an upward trend, a predicted bus protection start prompt message is reported.

[0024] A further improvement or preferred implementation of the foregoing method for predicting the trend of the power grid operation state. The steps for realizing the trend prediction of the differential current value further include:

[0025] Step 3: For predicting the trend of the differential current value of transformer protection, including C1 and C2;

[0026] C1. Judge the necessity of predicting the trend of the differential current value of transformer protection

[0027] Specifically, based on the detection data of the transformer protection device, when the maximum differential current of any phase measured < = 0.02In, no differential current trend analysis is performed; when the maximum differential current of any phase measured > 0.02In, differential current trend analysis is performed;

[0028] C2. Execute the trend prediction of the differential current value of transformer protection

[0029] Specifically, when 0.02In < the differential current measured of any phase < = 0.04In and shows an upward trend, a prediction main transformer protection differential current prompt message is reported after a 90S delay;

[0030] When 0.04In < the maximum differential current measured of any phase < 0.15Ie and shows an upward trend, a prediction differential current overlimit alarm prompt message is reported after a 90s delay;

[0031] When the differential current measured of any phase is greater than the differential current overlimit value, the protection device reports a differential current overlimit alarm signal after a 10s delay. If the corresponding alarm signal is not detected, it is given that the device should report a differential current overlimit alarm but actually does not report an alarm;

[0032] When the differential current overlimit value < the differential current of any phase < Id and shows an upward trend, a prediction main transformer protection start prompt message is reported.

[0033] A further improvement or preferred implementation of the foregoing method for predicting the trend of the power grid operation state further includes steps for realizing the trend prediction of the received and transmitted optical intensity, including:

[0034] Step 4: For realizing the trend prediction of the optical port transmission power, including D1 and D2;

[0035] D1. Judge the necessity of predicting the trend of the optical port transmission power

[0036] Specifically, when the monitored transmission power value is within 10% - 90% of the transmission power range, no trend prediction is performed, otherwise trend prediction is executed;

[0037] D2. Execute the trend prediction of the optical port transmission power

[0038] Specifically, when the predicted upper limit threshold is less than or equal to the transmission power value, which is less than the maximum value threshold and shows an upward trend, a reminder of the predicted optical port transmission power exceeding the upper limit will be given after a 90-second delay.

[0039] When the minimum threshold is less than the transmit power value and is less than or equal to the predicted lower limit threshold and shows a downward trend, a reminder of the predicted optical port transmit power exceeding the lower limit will be given after a 90-second delay.

[0040] When the maximum value threshold is less than or equal to the transmit power value, an alarm is reported that the transmit optical power of the optical port exceeds the upper limit;

[0041] When the transmit power value is less than or equal to the minimum threshold, an alarm is reported that the transmit optical power of the optical port exceeds the lower limit.

[0042] A further improved or preferred implementation of the aforementioned power grid operation status trend prediction method, for the steps of achieving light intensity trend prediction, further includes:

[0043] Step 5: Used to achieve sensitive power trend prediction for optical port reception, including E1 and E2;

[0044] E1. The necessity of determining the trend prediction of optical port receiving sensitivity power.

[0045] Specifically, if 0.9 * minimum receiver sensitivity power <= receiver sensitivity <= 0, no prediction is made; otherwise, trend prediction is performed.

[0046] E2. Perform optical port receiver sensitivity power trend prediction.

[0047] Specifically, when the minimum receiving sensitivity power < the receiving sensitivity power <= 0.9 * minimum receiving sensitivity power and is decreasing, a warning message indicating that the predicted optical port receiving sensitivity power has exceeded the lower limit will be reported after a delay of 90 seconds.

[0048] When the received sensitivity power is less than the minimum received sensitivity power, an alarm message indicating that the received sensitivity power has exceeded the lower limit is reported.

[0049] Its beneficial effects are as follows:

[0050] The power grid operation status trend prediction method of this application makes full use of the basic data of the existing real-time information data system of the power grid. By analyzing and predicting the simulated quantities that reflect the operating status of the device, such as the detected relay protection differential current value, light intensity, device temperature, and operating voltage, it can quickly and accurately make trend prediction analysis. Compared with the traditional manual on-site inspection mode, it has higher accuracy and efficiency, significantly improving the quality of inspection work. By analyzing the changing trends of relevant simulated quantities and risk prediction, it can detect potential defects of relay protection devices in advance and improve the reliability of device operation. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the trend prediction of differential current value for longitudinal differential line protection;

[0052] Figure 2 This is a schematic diagram of the trend prediction of differential current value for busbar protection;

[0053] Figure 3 This is a schematic diagram illustrating the trend prediction of differential current values ​​for transformer protection.

[0054] Figure 4 This is a schematic diagram of optical port transmit power trend prediction;

[0055] Figure 5 This is a schematic diagram illustrating the trend prediction of optical port receiving sensitivity power.

[0056] Figure 6 This is a schematic diagram illustrating the temperature trend prediction of the device;

[0057] Figure 7 This is a schematic diagram of working voltage trend prediction. Detailed Implementation

[0058] The present application will be described in detail below with reference to specific embodiments.

[0059] The power grid operation status trend prediction method of this application is mainly used to analyze the changing trends of relevant analog quantities and predict risks, discover potential defects of relay protection devices in advance, and improve the operational reliability of the devices.

[0060] The power grid operation status trend prediction method includes several parts: differential current value trend prediction, bus protection differential current value trend prediction, transformer protection differential current value trend prediction, optical port transmission power trend prediction, and optical port reception sensitive power trend prediction.

[0061] The steps used to achieve differential flow trend prediction specifically include:

[0062] Step 1: Used to predict the trend of differential current values ​​for longitudinal differential line protection, including A1 and A2;

[0063] A1. The necessity of predicting the trend of differential current value for longitudinal differential line protection.

[0064] like Figure 1 As shown, specifically, based on the detection data of the high-voltage line protection device, when the measured maximum secondary load current is <0.1In, no differential current trend analysis is performed; when the maximum differential current of any phase is <=0.02In, no differential current trend analysis is performed; In is the secondary rated current setting.

[0065] A2. Perform differential current value trend prediction for longitudinal differential line protection.

[0066] Specifically, when the maximum value of any phase differential current is within the normal differential current region (the measured maximum differential current of any phase ≤ 0.02In), it is considered normal differential current fluctuation, and no differential current trend analysis is performed;

[0067] When the maximum value of any phase differential current is within the differential current region of the prediction channel (0.02In < the measured maximum differential current of any phase ≤ 0.04In) and shows an upward trend (the average value of the sampling values of two consecutive points for three consecutive times), a reminder message of differential current in the prediction channel is reported after a 90S delay;

[0068] When the maximum value of any phase differential current is within the region where the predicted differential current exceeds the limit (0.04In < the measured maximum differential current of any phase < 0.9Id (Id is the fixed value of the differential protection operating current)) and shows an upward trend (the average value of the sampling values of two consecutive points for three consecutive times), a prompt message of predicted differential current exceeding the limit is reported after a 90s delay;

[0069] When the differential current of any phase is greater than 0.9Id (differential current threshold), the protection device shall report an alarm signal of differential current exceeding the limit, and after a 10s delay and a 10s extension, an alarm of long-term differential current in the channel is reported; if the corresponding alarm signal is not detected within 90S, it is indicated that the device should report an alarm of differential current exceeding the limit but actually no alarm is reported.

[0070] When the differential current value of any phase is within the region where the predicted pilot differential protection operates (0.9Id < the differential current of any phase < Id) and shows an upward trend (the average value of the sampling values of two consecutive points for three consecutive times), a prompt message of predicted pilot differential protection operation is reported after a 90s delay;

[0071] In is the fixed value of the secondary rated current (CT secondary value); Id is the fixed value of the differential protection operating current

[0072] When the current compensation function is enabled, the differential current compensated by the capacitive current is used for judgment; when the current compensation function is disabled, the conventional steady-state differential current is used for judgment;

[0073] Step 2: Used for predicting the trend of the differential current value of the bus protection, including B1 and B2;

[0074] B1. Judge the necessity of predicting the trend of the differential current value of the bus protection

[0075] As Figure 2 shown, specifically, based on the detection data of the bus protection device, when the measured differential current value is within the normal region (the measured maximum differential current of any phase ≤ 0.02In), it is considered that there is no differential current, and no differential current trend analysis is performed;

[0076] B2. Execute the prediction of the trend of the differential current value of the bus protection

[0077] Specifically, when the measured differential current value is within the predicted differential current area (0.02In < measured differential current of any phase <= 0.04In), and shows an upward trend (average value of two consecutive sampling values for 3 consecutive times), a predicted differential current prompt message is reported after a 90S delay;

[0078] When the measured differential current value is within the differential current area (0.04In < measured maximum differential current of any phase < 0.15Ie (Ie is the secondary rated current of the high-voltage side of the transformer)), a differential current prompt message for bus protection is reported;

[0079] When the measured differential current value is within the predicted differential protection startup area (0.15Ie < measured differential current of any phase < Id), and shows an upward trend (average value of two consecutive sampling values for 3 consecutive times), a predicted bus protection startup prompt message is reported;

[0080] Step 3: Used for predicting the trend of the differential current value of transformer protection, including C1 and C2;

[0081] C1. Judge the necessity of predicting the trend of the differential current value of transformer protection

[0082] As Figure 3 shown, specifically, when the measured differential current value is within the normal area (measured maximum differential current of any phase <= 0.02In), it is considered normal differential current fluctuation, and no differential current trend analysis is performed;

[0083] C2. Execute the prediction of the trend of the differential current value of transformer protection

[0084] Specifically, when the measured differential current is within the predicted differential current area (0.02In < measured differential current of any phase <= 0.04In), and shows an upward trend (average value of two consecutive sampling values for 3 consecutive times), a predicted differential current prompt message for main transformer protection is reported after a 90S delay;

[0085] When the measured differential current is within the predicted differential current overlimit area (0.04In < measured maximum differential current of any phase < 0.15Ie (Ie is the secondary rated current of the high-voltage side of the transformer)), and shows an upward trend (average value of two consecutive sampling values for 3 consecutive times), a predicted differential current overlimit warning prompt message is reported after a 90s delay;

[0086] When the measured differential current of any phase is greater than the differential current overlimit value (for example, 0.15Ie for NARI Technology), the protection device reports a differential current overlimit warning signal after a delay of 10s. If the corresponding warning signal is not detected, it is indicated that the device should report a differential current overlimit warning but actually did not report the warning;

[0087] When the measured differential current is within the predicted main transformer protection startup area (differential current overlimit value < differential current of any phase < Id), and shows an upward trend (average value of two consecutive sampling values for 3 consecutive times), a predicted main transformer protection startup prompt message is reported;

[0088] Step 4: Used to predict the trend of optical port transmission power, including D1 and D2;

[0089] The optical port transmit power involves two parameters: the minimum transmit power and the maximum transmit power. For cases where the maximum transmit power is not specified in the manufacturer's manual, the maximum value can be assumed to be 0dBm.

[0090] D1. The necessity of judging the trend prediction of optical port transmit power

[0091] like Figure 4 As shown, specifically, when the monitored transmission power value is in the normal area shown in the figure above, it is within the normal range and no trend prediction is made. The normal range is 10% to 90% of the transmission power range.

[0092] D2. Perform optical port transmit power trend prediction

[0093] Specifically, when the transmit power value is in the predicted upper limit region (predicted upper limit threshold <= transmit power value < maximum value threshold) and shows an upward trend (average of 3 consecutive 2-point sampling values), a warning of predicted optical port transmit power exceeding the upper limit is given after a 90-second delay.

[0094] When the transmit power value is in the predicted lower limit region (when the minimum threshold < transmit power value <= predicted lower limit threshold) and shows a downward trend (average of 3 consecutive 2-point sampling values), a reminder of the predicted optical port transmit power exceeding the lower limit is given after a 90s delay.

[0095] When the transmit power value is in the upper limit alarm area (maximum value threshold <= transmit power value), an upper limit alarm for optical port transmit power will be reported.

[0096] When the transmit power value is in the lower limit alarm zone (transmit power value <= minimum threshold), an optical port transmit power lower limit alarm will be reported.

[0097] Step 5: Used to achieve sensitive power trend prediction for optical port reception, including E1 and E2;

[0098] E1. The necessity of determining the trend prediction of optical port receiving sensitivity power.

[0099] like Figure 5 As shown, specifically, the optical port receiving sensitivity power involves a parameter, namely the minimum receiving sensitivity power. When the optical port receiving sensitivity power is in the normal range (0.9 * minimum receiving sensitivity power <= receiving sensitivity <= 0), it is considered normal receiving power and no prediction is made.

[0100] E2. Perform optical port receiver sensitivity power trend prediction.

[0101] Specifically, when the optical port receiving sensitivity power is in the predicted lower limit region (minimum receiving sensitivity power < receiving sensitivity power <= 0.9 * minimum receiving sensitivity power) and is showing a downward trend (average of 3 consecutive 2-point sampling values), a warning message indicating that the predicted optical port receiving sensitivity power has exceeded the lower limit will be reported after a 90-second delay.

[0102] When the optical port receive sensitivity power is in the lower limit alarm area (receive sensitivity power < minimum receive sensitivity power), a receive sensitivity power lower limit alarm message will be reported.

[0103] Specifically, in practical implementation, it also includes steps for predicting the temperature trend of the device, including F1 and F2:

[0104] F1. The necessity of judging the temperature trend prediction of the device

[0105] like Figure 6 As shown, specifically, the difference between the internal temperature of the measuring device and the ambient temperature is calculated as the current measurement value. This measurement value is then compared with the measurement difference calculated when the ambient temperature was similar in the previous measurement (the difference between the two ambient temperatures is within 10 degrees). The difference is calculated, and when the difference is within the normal variation range (the difference is within 5 degrees), it is considered a normal temperature change and no prediction is made.

[0106] F2. Temperature Trend Prediction of Actuator

[0107] Specifically, when the difference is in the area of ​​rapid temperature rise in the prediction (the difference is between 5 and 7.5 degrees), a warning message about rapid temperature rise in the prediction device will be issued after a delay of 90 seconds.

[0108] When the difference is in the area where the predicted temperature is rising rapidly (the difference is between 7.5 degrees and 10 degrees), a warning message about the rapid temperature rise of the prediction device will be issued after a delay of 90 seconds.

[0109] When the temperature difference is in the area where the alarm is sent too quickly (the difference exceeds 10 degrees), an alarm signal for the device temperature rising too quickly will be issued.

[0110] (5) When the internal temperature of the measured device exceeds 80 degrees, an over-temperature alarm signal will be issued.

[0111] It also includes steps for predicting operating voltage trends, including G1 and G2:

[0112] G1. The necessity of judging the trend prediction of working voltage

[0113] like Figure 7 As shown, specifically, when the device's operating voltage is within the normal range (0.9 * standard value <= operating voltage <= 1.1 * standard value), it is considered normal operating voltage and no prediction is made.

[0114] G2. Perform working voltage trend prediction

[0115] Specifically, when the device's operating voltage value is in the predicted upper limit range (1.1 * standard value < operating voltage <= 1.2 * standard value) and shows an upward trend (average of 3 consecutive 2-point sampling values), a warning will be issued after a 90-second delay to indicate that the device's operating voltage is exceeding the upper limit.

[0116] When the device's operating voltage value is in the predicted lower limit region (0.8*standard value <= operating voltage < 0.9*standard value) and shows a downward trend (average of 3 consecutive 2-point sampling values), a warning will be issued after a 90-second delay to indicate that the device's operating voltage is below the lower limit.

[0117] When the device's operating voltage value is in the upper limit alarm zone (operating voltage > 1.2 * standard value), an upper limit alarm for the device's operating voltage will be reported immediately.

[0118] When the device's operating voltage value falls within the lower limit alarm zone (operating voltage < 0.8 * standard value), an lower limit alarm for the device's operating voltage will be reported immediately.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A method for predicting the trend of power grid operation status, characterized in that, It includes steps for realizing the prediction of the differential current value trend, including: Step 1: For realizing the prediction of the differential current value trend of the longitudinal differential line protection, including A1 and A2; A1. Judging the necessity of predicting the differential current value trend of the longitudinal differential line protection Specifically, based on the detection data of the high-voltage line protection device, when the measured maximum secondary load current < 0.1In, no differential current trend analysis is performed; when the maximum value of any phase differential current <= 0.02In, no differential current trend analysis is performed; In is the secondary rated current setting value; A2. Executing the prediction of the differential current value trend of the longitudinal differential line protection Specifically, when 0.02In < the maximum measured differential current of any phase <= 0.04In and showing an upward trend, a reminder message of differential current in the predicted channel is reported after a 90-second delay; When 0.04In < the maximum measured differential current of any phase < 0.9Id and showing an upward trend, a prompt message of differential current exceeding the limit in the prediction is reported after a 90-second delay; Id is the differential action current setting value; When the differential current of any phase is greater than 0.9Id, the protection device shall report an alarm signal of differential current exceeding the limit, and after a 10-second delay and a 10-second broadening, an alarm of long-term differential current in the channel is reported; When 0.9Id < the differential current of any phase < Id and showing an upward trend, a prompt message of the action of the predicted pilot differential protection is reported after a 90-second delay.

2. The method for predicting the trend of power grid operation status according to claim 1, characterized in that, During the process of A2. Executing the prediction of the differential current value trend of the longitudinal differential line protection, when the differential current of any phase is greater than 0.9Id and the protection device shall report an alarm signal of differential current exceeding the limit, if the corresponding alarm signal is not detected within 9 minutes, it is given that the device should report an alarm of differential current exceeding the limit but actually no alarm is reported.

3. The method for predicting the trend of power grid operation status according to claim 1, characterized in that, The so-called upward trend specifically means that the average value of at least 3 consecutive 2-point sampling values obtained by continuous measurement is continuously increasing.

4. The method for predicting the trend of power grid operation status according to claim 1, characterized in that, The steps for realizing the prediction of the differential current value trend also include: Step 2: For realizing the prediction of the differential current value trend of the bus protection, including B1 and B2; B1. Judging the necessity of predicting the differential current value trend of the bus protection Specifically, based on the detection data of the bus protection device, when the maximum measured differential current of any phase <= 0.02In, no differential current trend analysis is performed; when the maximum measured differential current of any phase > 0.02In, differential current trend analysis is performed; B2. Executing the prediction of the differential current value trend of the bus protection Specifically, when 0.02In < the measured differential current of any phase <= 0.04In and showing an upward trend, a prompt message of differential current in the prediction is reported after a 90-second delay; When 0.04In < the maximum measured differential current of any phase < 0.15Ie, a prompt message of differential current in the bus protection is reported; Ie is the secondary rated current of the high-voltage side of the transformer When 0.15Ie < the measured differential current of any phase < Id and showing an upward trend, a prompt message of the start of the predicted bus protection is reported.

5. The method for predicting the trend of power grid operation status according to claim 1, characterized in that, The steps for realizing the prediction of the differential current value trend also include: Step 3: For realizing the prediction of the differential current value trend of the transformer protection, including C1 and C2; C1. Judging the necessity of predicting the differential current value trend of the transformer protection Specifically, based on the detection data of the transformer protection device, when the maximum measured differential current of any phase <= 0.02In, no differential current trend analysis is performed; when the maximum measured differential current of any phase > 0.02In, differential current trend analysis is performed; C2. Executing the prediction of the differential current value trend of the transformer protection Specifically, when 0.02In < the measured differential current of any phase <= 0.04In and shows an upward trend, a predictive differential current prompt message for the main transformer protection is reported after a 90-second delay; When 0.04In < the measured maximum differential current of any phase < 0.15Ie and shows an upward trend, a predictive differential current overlimit warning prompt message is reported after a 90-second delay; When the measured differential current of any phase is greater than the differential current overlimit value, the protection device reports a differential current overlimit warning signal after a 10-second delay. If the corresponding warning signal is not detected, it is indicated that the device should report a differential current overlimit warning but actually did not report the warning; When the differential current overlimit value < the differential current of any phase < Id and shows an upward trend, a predictive main transformer protection startup prompt message is reported.

6. The method for predicting the trend of power grid operation status according to claim 1, characterized in that, It also includes steps for implementing the prediction of the received and transmitted optical intensity trends, including: Step Four: For implementing the prediction of the optical port transmission power trend, including D1 and D2; D1. Determine the necessity of predicting the optical port transmission power trend Specifically, when the monitored transmission power value is within 10% - 90% of the transmission power range, no trend prediction is performed; otherwise, trend prediction is executed; D2. Execute the prediction of the optical port transmission power trend Specifically, when the predicted upper limit threshold <= the transmission power value < the maximum threshold and shows an upward trend, a predictive optical port transmission power over-upper limit reminder is given after a 90-second delay; When the minimum threshold < the transmission power value <= the predicted lower limit threshold and shows a downward trend, a predictive optical port transmission power over-lower limit reminder is given after a 90-second delay; When the maximum threshold <= the transmission power value, an optical port transmitted optical power over-upper limit warning is reported; When the transmission power value <= the minimum threshold, an optical port transmitted optical power over-lower limit warning is reported.

7. The method for predicting the trend of power grid operation status according to claim 6, characterized in that, The steps for implementing the prediction of the received and transmitted optical intensity trends also include: Step Five: For implementing the prediction of the optical port received sensitivity power trend, including E1 and E2; E1. Determine the necessity of predicting the optical port received sensitivity power trend Specifically, when 0.9 * the minimum received sensitivity power <= the received sensitivity <= 0, no prediction is performed; otherwise, trend prediction is executed; E2. Execute the prediction of the optical port received sensitivity power trend Specifically, when the minimum received sensitivity power < the received sensitivity <= 0.9 * the minimum received sensitivity power and shows a downward trend, a predictive optical port received sensitivity power over-lower limit prompt message is reported after a 90-second delay; When the received sensitivity < the minimum received sensitivity power, a received sensitivity power over-lower limit warning message is reported.

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