Monitoring method for synchronous grid-connected closing of electric power system and related product

Abstract

The invention relates to the technical field of electric power systems, in particular to a monitoring method for synchronous grid-connected closing of an electric power system and a related product, and the method comprises the steps: collecting voltage waveforms of a generator side and a power grid side in real time; acquiring system delay time; predicting a future synchronization moment when the phase angle difference reaches a preset target value; calculating an optimal switching-on instruction issuing moment; acquiring an actual instruction issuing moment when a monitoring system synchronizing device issues a closing instruction; comparing the optimal switching-on instruction issuing moment with the actual instruction issuing moment, and if the time error is smaller than a set value, judging that switching-on is performed in the same period; otherwise, non-synchronous closing is determined; according to the method, a theoretical optimal switching-on instruction issuing moment is calculated based on the instantaneous phase angle difference, the slip frequency and the slip angular acceleration, and is compared with an instruction moment actually issued by a field synchronizing device, so that the performance of the existing device is quantitatively evaluated.

Description

Technical Field

[0001] This invention relates to the field of power system technology, specifically to a monitoring method and related products for synchronous grid connection and closing of power systems. Background Technology

[0002] Connecting generator sets to the power grid is a fundamental and crucial operational step in the operation of a power system. To ensure the safe and stable operation of the power grid, the amplitude, frequency, and phase angle of the generator set's output voltage must be strictly consistent with the corresponding parameters of the grid voltage or within a very small allowable error range before grid connection. This process is called "synchronous grid connection".

[0003] In traditional generator grid connection operations, especially during on-site commissioning or testing phases (such as simulating synchronization tests), technicians typically need to use instruments such as oscilloscopes to monitor the voltage waveforms at the generator and grid sides in real time. When technicians visually determine that the frequency, amplitude, and phase difference of the two voltage waveforms meet the grid connection conditions, they manually or through the control system issue a closing command to close the output circuit breaker and complete the grid connection.

[0004] However, in actual operation, there is an inherent electromechanical delay time between the control system issuing the closing command and the final physical closure of the circuit breaker's mechanical contacts. During this delay, the phase angle difference between the generator and the grid continues to change with the slip frequency. If the slip frequency is large, even if the phase angle difference meets the requirements at the instant the command is issued, it may have exceeded the allowable range by the time the circuit breaker actually closes, leading to grid connection impact, and in severe cases, even damaging equipment or causing grid disturbances.

[0005] Furthermore, the operation process often involves complex temporary wiring and on-site judgment, which not only consumes time in preparation and is prone to human error, reducing the accuracy and reliability of the test, but also poses certain safety risks if the operation is improper. Therefore, for existing synchronizing devices in power plants (whether automatic or manual control), there is currently a lack of an effective and high-precision online monitoring and evaluation method to ensure that the circuit breaker closes at the true optimal synchronization point, and whether the timing of the closing command issued during actual operation can accurately take into account and compensate for the aforementioned electromechanical delay time. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a monitoring method and related products for synchronous grid connection and closing of power systems. By using instruments to collect signal status, corresponding steps are triggered to start waveform recording, waveform capture, data recording, and test report generation, thereby avoiding errors caused by human operation and improving the reliability and accuracy of test data.

[0007] This invention is achieved through the following technical solution:

[0008] A monitoring method for synchronous grid connection and closing of a power system includes:

[0009] The voltage waveforms of the generator side and the grid side are acquired in real time; and the dynamic synchronization parameters between the generator side and the grid side are calculated in real time based on the voltage waveforms. The dynamic synchronization parameters include the phase angle difference and the slip angle frequency.

[0010] The system delay time is the time difference between the time when the monitoring system synchronization device issues a closing command and the circuit breaker physically closes.

[0011] Based on the phase difference and slip angle frequency, predict the future synchronization time when the phase difference reaches the preset target value.

[0012] The optimal time to issue the closing command is calculated based on the future synchronization time and the system delay time.

[0013] Obtain the actual time when the closing command is issued by the synchronizing device of the monitoring system;

[0014] By comparing the optimal closing command issuance time with the actual command issuance time, if the time error is less than the set value, it is determined to be synchronous closing; otherwise, it is determined to be asynchronous closing.

[0015] Alternatively, methods for predicting future synchronization moments include:

[0016] Get the current time t current Instantaneous phase angle difference Δθ(t) current Instantaneous slip angular frequency ω slip (t current and instantaneous slip angular acceleration α slip (t current );

[0017] Construct a second-order Taylor expansion of the phase difference over time to predict future phase differences.

[0018] Where Δt is the predicted time interval from the current time to the future synchronization time;

[0019] Let Δθ(t) current +Δt)=0, and solve to obtain a mathematical solution; select and determine the smallest positive real number solution from the mathematical solutions as the final prediction time interval Δt;

[0020] Calculate and determine the future synchronization time t sync , t sync =t current +Δt.

[0021] Optionally, it also includes:

[0022] After the circuit breaker is actually closed, the actual phase angle difference at the moment of closure is measured.

[0023] The system delay time is updated based on the deviation between the actual phase angle difference and the preset target value.

[0024] Methods for updating system latency include:

[0025] After the kth synchronization test, based on the actual phase angle difference Δθ at the moment of closing. actual (k) and the actual slip angular frequency ω slip_actual (k) Calculate instantaneous time error

[0026] Calculate the normalized magnitude of the error Among them, t errormax The preset maximum effective error threshold;

[0027] Preset minimum learning rate α min and maximum learning rate α max The learning rate α(k) for the k-th update is calculated using linear interpolation, where α(k) = α min +(α max -α min )·η(k);

[0028] Update to obtain new system latency T delay (k+1)=T delay (k)+α(k·t) error (k), where T delay (k) represents the system delay time for performing the k-th synchronization test.

[0029] Furthermore, it also includes an initial system delay time calibration method for determining an initial value for the system delay time, the calibration method comprising:

[0030] Calculate the single measurement delay T for each test i. measured (i)=t closure (i)-t command (i), where t command (i) represents the moment when the command is issued during the i-th calibration test, t closure (i) is the moment when the circuit breaker confirms physical closure during the i-th calibration test;

[0031] After performing N independent calibration tests consecutively, and then completing N more tests, the original sample set S is obtained.

[0032] Sort the sample set S and calculate the first quartile Q1 and the third quartile Q3. Calculate the interquartile range IQR, where IQR = Q3 - Q1.

[0033] Iterate through each element T in the original sample set S measured (i) retain the condition that Lower_Bound≤T measured (i) elements ≤ Upper_Bound are added to the new valid sample set S. filtered In this context, Lower_Bound = Q1 - 1.5·IQR is the lower boundary of the valid data, and Upper_Bound = Q3 + 1.5·IQR is the upper boundary of the valid data.

[0034] For the effective sample set S filtered Calculate the arithmetic mean of all elements to obtain the initial system delay time. Among them, |S filtered | represents the number of elements in the valid sample set.

[0035] Optionally, before executing the closing command, the circuit breaker control system performs a precondition check, the method of which includes:

[0036] Real-time monitoring of the voltage difference ΔU and frequency difference Δf between the generator side and the grid side.

[0037] Determine whether the voltage difference ΔU is less than a preset allowable voltage difference threshold;

[0038] Determine whether the frequency difference Δf is less than a preset allowable frequency difference threshold;

[0039] If all values ​​are less than the preset allowable threshold, then the closing command is executed; otherwise, execution is terminated.

[0040] Optionally, if the closing command is terminated, the following steps are performed:

[0041] Record and save dynamic synchronization parameters within a specific time window before the termination or failure, wherein the dynamic synchronization parameters include at least the time series of voltage difference, frequency difference and slip angular frequency;

[0042] Based on the captured time-series data, perform the following logical judgments to determine the cause classification:

[0043] If, within the observation time window prior to the abort or failure, there exists a continuous time period whose duration exceeds a preset frequency duration threshold, and within this continuous time period, the absolute value of the slip angle frequency is always greater than the preset slip threshold, then the cause will be classified as excessively fast frequency slip.

[0044] If a failure occurs after closing, and the absolute value of the instantaneous time error calculated from the actual phase angle difference and the actual slip angular frequency is greater than a preset delay error threshold, the cause will be classified as system delay model mismatch.

[0045] If, within the observation time window before the synchronization process is terminated, there is a continuous time period whose duration exceeds a preset voltage duration threshold, and the absolute value of the voltage difference is always greater than a preset voltage difference allowable threshold during this continuous time period, then the cause will be classified as a continuous voltage difference exceeding the limit.

[0046] Optionally, after each monitoring process is completed, structured test records can be automatically generated, using methods including:

[0047] Capture and store time-series data of key dynamic synchronization parameters within a time window surrounding the closing event; the time window at least covers the time from the actual command issuance time / optimal command issuance time to the actual physical closing time of the circuit breaker, and the time-series data at least includes data on the phase angle difference changing over time;

[0048] Record and save all key synchronization parameters at the moment of closing, including: actual voltage difference, actual frequency difference, and actual phase angle difference;

[0049] Record and save the core computational parameters used in this synchronization process, including at least the system latency used during prediction;

[0050] Record the occurrence time of key events, including at least: the calculated optimal command issuance time, the actual command issuance time, and the actual physical closing time fed back by the circuit breaker position node;

[0051] Record the final result of this closing time determination, including whether it is synchronous closing or asynchronous closing;

[0052] Record the execution status of the closing command, including whether the closing was successful or failed. If the closing failed, record the corresponding fault classification label.

[0053] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the monitoring method for synchronous grid connection and closing of a power system as described above.

[0054] A computer program product includes a computer program / instructions that, when executed by a processor, implement the monitoring method for synchronous grid connection and closing of a power system as described above.

[0055] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0056] This invention calculates a theoretically optimal closing command time based on instantaneous phase angle difference, slip frequency, and slip angular acceleration, and compares it with the actual command time issued by the field synchronizing device, thereby quantitatively evaluating the performance of the existing device.

[0057] This invention uses a second-order dynamic model based on the comprehensive slip angle acceleration to predict and calculate the theoretically optimal closing time, which serves as a comparison standard for the actual closing time. This overcomes the subjectivity and ambiguity of the traditional oscilloscope visual method and achieves a leap from qualitative observation to quantitative analysis of synchronous closing performance.

[0058] By introducing an adaptive delay parameter correction mechanism based on dynamic learning rate, this invention can update the system delay time of existing synchronous devices, providing a system delay time that traditional monitoring methods cannot update, thus avoiding the hidden grid connection impact problem caused by improper delay compensation.

[0059] By integrating monitoring, benchmark calculation, and logical fault diagnosis, the human error and safety risks caused by traditional manual observation and wiring are eliminated, and the test preparation and report writing time is significantly shortened. Attached Figure Description

[0060] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, but do not constitute a limitation on the embodiments of the present invention.

[0061] Figure 1 This is a flowchart illustrating the monitoring method for synchronous grid connection and closing of a power system according to the present invention.

[0062] Figure 2 This is a flowchart illustrating the system delay time calibration and update method according to the present invention. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0064] It should also be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0065] Where there is no conflict, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0066] Example 1

[0067] like Figure 1As shown, this embodiment first establishes a mathematical model by real-time monitoring of key dynamic parameters of the generator and the power grid; then, it predicts and calculates an optimal control command with lead time; finally, it compares and analyzes the timing of the optimal control command with the actual command timing issued by the synchronization device of the monitoring system to determine whether the circuit breaker is synchronized. The specific steps are as follows:

[0068] Real-time calculation of dynamic synchronization parameters:

[0069] The voltage waveforms of the generator side and the grid side are acquired in real time; and the dynamic synchronization parameters between the generator side and the grid side are calculated in real time based on the voltage waveforms. The dynamic synchronization parameters include the phase angle difference and the slip angle frequency.

[0070] The AC voltage waveforms at the generator output and the grid side are continuously and in real time acquired through high-frequency sampling. Then, based on the acquired digital waveform data, the core dynamic synchronization parameters between the two voltage signals are calculated in real time.

[0071] Phase angle difference: refers to the angular difference between the generator voltage vector and the grid voltage vector at any given instant. This is a core indicator for determining synchronization; ideally, this value should be zero at the moment of grid connection.

[0072] Slip angular frequency: refers to the rate of change of phase angle difference over time, reflecting the difference in rotational speed between the generator and the power grid, and is used to predict future trends in phase angle difference.

[0073] Obtaining system latency:

[0074] The system delay time is obtained, which is the time difference between the time the monitoring system synchronizing device issues a closing command and the time the circuit breaker is physically closed.

[0075] The system delay time represents the total time elapsed from the electrical signal that sends the closing command from the synchronizing device of the monitoring system to the complete operation of the internal mechanical structure of the circuit breaker and the final physical closure of the main contacts.

[0076] Prediction of future synchronization time:

[0077] Based on the phase difference and slip angle frequency, predict the future synchronization time when the phase difference reaches the preset target value.

[0078] By using the real-time calculated current phase difference and slip angular frequency, a prediction algorithm can predict at what point in the future the phase difference will naturally decrease to a preset target value (usually zero).

[0079] Calculation of the optimal instruction timing:

[0080] The optimal time to issue the closing command is calculated using the future synchronization time and the system delay time.

[0081] Taking into account system latency, the synchronization device in the monitoring system does not wait until the required synchronization moment to issue the command. Instead, it calculates the actual command issuance time by subtracting the system latency from the future synchronization moment. By issuing the command in advance, the circuit breaker closes precisely at the predicted ideal synchronization moment after the command has traveled a distance equal to the system latency.

[0082] Obtaining the actual time of instruction issuance:

[0083] Obtain the actual time when the closing command is issued by the synchronous device of the monitoring system.

[0084] The actual time of the closing command can be obtained from the internal clock module of the synchronous device in the monitoring system.

[0085] Time Comparison:

[0086] By comparing the optimal closing command issuance time with the actual command issuance time, if the time error is less than the set value, it is determined to be synchronous closing; otherwise, it is determined to be asynchronous closing.

[0087] A preset value is established, and then the two times are compared. The absolute value of the time error is calculated. If the absolute value is less than the preset value, it proves that the actual command issuance time is close to the optimal closing command issuance time, indicating that the error is within an acceptable range, and synchronous closing is considered to have been achieved. Otherwise, it proves that the error is too large, and asynchronous closing has occurred.

[0088] Example 2

[0089] This embodiment provides a specific method for the "prediction of future synchronization time" step in the aforementioned embodiments.

[0090] This embodiment upgrades the prediction of the synchronization point from a simple linear extrapolation model to a second-order dynamic prediction model that can describe the changes in system acceleration. Traditional methods typically assume that the slip frequency between the generator and the grid is constant, but in actual operating conditions, the slip frequency itself may change during acceleration or deceleration.

[0091] The specific methods for predicting future synchronization moments include the following key technical steps:

[0092] Get the current time t current Instantaneous phase angle difference Δθ(t) current Instantaneous slip angular frequency ω slip (t current and instantaneous slip angular acceleration α slip (t current Instantaneous slip angular acceleration is the derivative of slip angular frequency with respect to time (i.e., the second derivative of phase difference), which describes how fast the slip angular frequency changes.

[0093] Based on Newton's kinematics formulas, a second-order Taylor expansion of the phase difference over time is constructed to predict future phase differences: Where Δt is the predicted time interval from the current time to the future synchronization time;

[0094] The goal is to find the future phase angle difference Δθ(t) current The time interval Δt when +Δt) is zero. Therefore, we set the above expression to zero: And solve for the mathematical solution.

[0095] This is a standard quadratic equation in one variable Ax with respect to the unknown Δt. 2 +Bx+C=0, where: Using the quadratic formula, we can solve for Δt:

[0096] Substituting A, B, and C, we obtain the final expression for calculating the prediction time interval Δt:

[0097]

[0098] The above formula will produce two solutions, and the choice needs to be made based on the physical meaning:

[0099] Valid solution: Find the smallest positive real number solution, which represents the fastest time required to reach the synchronization point from the current moment.

[0100] Invalid solutions: Negative solutions represent solutions that were synchronized at some point in the past and are meaningless.

[0101] Complex solution: i.e., the discriminant under the radical sign This means that under this acceleration model, the system will never reach the synchronization point. At this point, the synchronization operation should be paused, and a better opportunity should be waited for.

[0102] Therefore, in t current At any given moment, by processing the high-frequency sampled voltage waveform data, the current Δθ and ω are calculated in real time. slip and α slip Substitute these three parameters into the final expression above and calculate the value of the discriminant.

[0103] If the discriminant is less than zero, then the prediction is terminated.

[0104] If the discriminant is greater than or equal to zero, then the solutions for the two Δt are calculated, and the smallest positive real solution is selected from the mathematical solutions as the final prediction time interval Δt.

[0105] Calculate and determine the future synchronization time t sync , t sync =t current +Δt.

[0106] Example 3

[0107] like Figure 2 As shown, this embodiment presents two key processing methods for system delay time: one is the initial value calibration method for the physical delay of the circuit breaker, and the other is the online monitoring and quantification of the error of the synchronization device of the external monitoring system in the delay compensation strategy.

[0108] The first stage is the initial calibration stage: Before the system is officially put into predictive synchronization tasks, a calibration procedure will be executed. Through repeated test measurements and statistical algorithms, the measurement data will be processed to filter out random errors and abnormal interference, thereby calculating an initial baseline value for the average delay level of the device in the current state.

[0109] The second stage is the online monitoring and evaluation stage of the synchronization device delay compensation error:

[0110] After the circuit breaker is actually closed, the actual phase angle difference at the moment of closure is measured.

[0111] After the closing command is issued, the system records the moment when the circuit breaker actually closes physically by monitoring the position feedback node of the circuit breaker. The system will then measure the actual phase angle difference at that moment again.

[0112] The measured actual phase angle difference is compared with the ideal target value (zero). If a deviation exists, the system delay time is corrected and updated.

[0113] Based on the deviation between the actual phase angle difference and the preset target value, and based on the measured actual phase angle difference, the slip angular frequency at the moment of closing, and the system delay time of this closing operation, the ideal moment when the closing command should be issued to make the actual phase angle difference of this closing zero is calculated, which is called the theoretical optimal command moment.

[0114] The system captures and records the actual moment when the external monitoring system's synchronizing device issues the closing command. Then, by comparing the "theoretically optimal command moment" with the "actual command issuance moment," the time deviation between the two is calculated, and the system delay time is updated.

[0115] The system delay time calibration method used to determine the initial value of the system delay time has the following specific steps:

[0116] Calculate the single measurement delay T for each test i. measured (i)=t closure (i)-t command (i), where tcommand (i) represents the moment when the command is issued during the i-th calibration test, t closure (i) is the moment when the circuit breaker confirms physical closure during the i-th calibration test;

[0117] After performing N independent calibration tests consecutively, and then completing N more tests, the original sample set S is obtained.

[0118] To eliminate extreme outliers that may be caused by random factors in the sample data, this method uses the interquartile range (IQR) for data cleaning. The sample set S is sorted, and the first quartile Q1 and the third quartile Q3 are calculated. The interquartile range IQR is then calculated as IQR = Q3 - Q1.

[0119] Iterate through each element T in the original sample set S measured (i) retain the condition that Lower_Bound≤T measured (i) elements ≤ Upper_Bound are added to the new valid sample set S. filtered In this context, Lower_Bound = Q1 - 1.5·IQR is the lower boundary of valid data, and Upper_Bound = Q3 + 1.5·IQR is the upper boundary of valid data; any measurement value outside this range will be considered an outlier and removed.

[0120] For the effective sample set S filtered Calculate the arithmetic mean of all elements to obtain the initial system delay time. Among them, |S filtered | represents the number of elements in the valid sample set.

[0121] The specific steps for updating the system delay time are as follows:

[0122] After the kth synchronization test, based on the actual phase angle difference Δθ at the moment of closing. actual (k) and the actual slip angular frequency ω slip_actual (k) Calculate instantaneous time error This indicates the amount of time that the actual closing time is earlier or later than the ideal synchronization point (Δθ=0).

[0123] The measured angle error (Δθ) actual ) is converted into time error (t) error For example, if the slip frequency is 1 degree / second, and the phase angle difference measured when closing the circuit is +0.5 degrees (closing the circuit is too late), then the time error is +0.5 seconds.

[0124] To establish a unified evaluation standard, the normalized error magnitude was calculated. Among them, t errormaxThe preset maximum effective error threshold is used to convert an error value with physical units (seconds) into a dimensionless standard amplitude factor ranging from 0 to 1.

[0125] Preset minimum learning rate α min and maximum learning rate α max The learning rate α(k) for the k-th update is calculated using linear interpolation, where α(k) = α min +(α max -α min )·η(k).

[0126] When the error is very small and η(k) approaches 0, the value of α(k) will approach α. min This results in smaller system correction actions and higher stability.

[0127] When the error is large and η(k) approaches 1, the value of α(k) will approach α. max This allows the system to make larger corrections and has high responsiveness.

[0128] Update to obtain new system latency T delay (k+1)=T delay (k)+α(k·t) error (k), where T delay (k) represents the system delay time for performing the k-th synchronization test.

[0129] Example 4

[0130] This embodiment illustrates two key technical mechanisms set up to ensure the safety and reliability of the synchronous grid connection process: one is the precondition judgment mechanism before the instruction is issued, and the other is the fault diagnosis mechanism after the synchronous task fails or is terminated.

[0131] After calculating the optimal closing time, the command is not executed immediately. Instead, a safety check is performed to verify that both grid-connected devices meet the minimum requirements for basic synchronization elements such as voltage and frequency. The command is only released when all basic conditions are met; otherwise, the operation is aborted to avoid grid connection under unsafe or unstable conditions. The specific steps are as follows:

[0132] Real-time monitoring of the voltage difference ΔU and frequency difference Δf between the generator side and the grid side.

[0133] Determine whether the voltage difference ΔU is less than a preset allowable voltage difference threshold;

[0134] Determine whether the frequency difference Δf is less than a preset allowable frequency difference threshold;

[0135] If all values ​​are less than the preset allowable threshold, then the closing command is executed; otherwise, execution is terminated.

[0136] The system determines that the current state is suitable for closing the circuit and allows the previously calculated closing command to proceed only when both the voltage difference and frequency difference conditions are met simultaneously (i.e., both are less than their respective preset allowable thresholds). If either condition is not met, the system will immediately terminate the execution of the closing command to ensure safety.

[0137] When a synchronization task is aborted, or when the command is granted but the final grid connection result still fails, this mechanism will automatically activate. It will analyze various dynamic data to deduce the root cause of the failure or abortion and provide a diagnostic conclusion. The specific steps are as follows:

[0138] Record and save dynamic synchronization parameters within a specific time window before the termination or failure, wherein the dynamic synchronization parameters include at least the time series of voltage difference, frequency difference and slip angular frequency;

[0139] Based on the captured time-series data, perform the following logical judgments to determine the cause classification:

[0140] Diagnosis of excessive frequency slip: If, within the observation time window before the termination or failure, there is a continuous time period whose duration is greater than a preset frequency duration threshold, and the absolute value of the slip angular frequency is always greater than the preset slip threshold during this continuous time period, then the cause is classified as excessive frequency slip.

[0141] This logic checks whether the slip frequency (i.e., the rate of change of the phase angle difference) remains excessively high over a period of time. If the system determines that the slip frequency has consistently failed to stabilize at a controllable low level, the failure is attributed to this, indicating that the generator speed is too fast or too slow, exceeding the system's controllable synchronization range.

[0142] System delay model mismatch diagnosis: If a failure event occurs after closing, and the absolute value of the instantaneous time error calculated from the actual phase angle difference and the actual slip angular frequency is greater than a preset delay error threshold, the cause will be classified as system delay model mismatch.

[0143] This logic is activated under the specific condition of "failure after closing". By calculating the time deviation corresponding to the actual closing error, the accuracy of the "system delay time" parameter, which is the core of the prediction in this invention, is determined. If the time deviation is too large, it indicates that the problem is not due to external operating conditions, but rather that the prediction model parameters of the system itself need to be corrected.

[0144] Diagnosis of persistent voltage difference exceeding limits: If, within the observation time window before the synchronization process is terminated, there is a continuous time period whose duration exceeds a preset voltage duration threshold, and the absolute value of the voltage difference is always greater than a preset voltage difference allowable threshold during this continuous time period, then the cause is classified as persistent voltage difference exceeding limits.

[0145] This logic is used to diagnose events that are interrupted due to precondition checks. It analyzes historical data to determine if the voltage difference has consistently failed to meet requirements for a period of time. If so, the cause is clearly identified, and the operator is informed that the problem lies in the voltage regulation process.

[0146] Example 5

[0147] This embodiment supplements the above embodiment by providing a specific method for automatically generating structured test records after the method is executed. The aim is to create a traceable digital archive for each synchronization operation, providing comprehensive data support for subsequent analysis, verification, and report generation. Specific steps include:

[0148] Capture and store time-series data of key dynamic synchronization parameters within a time window surrounding the closing event; the time window covers at least from the moment the optimal command is issued to the moment the circuit breaker actually closes, and the time-series data includes at least data on the phase angle difference changing over time; for example, a complete curve of the phase angle difference changing over time can be recorded from before the closing command is issued to a period after the actual closing, allowing technicians to replay the entire grid connection dynamic process afterward, intuitively observe the convergence behavior of the phase angle difference, determine whether there are abnormal oscillations, and thus conduct an in-depth evaluation of the performance of the prediction model.

[0149] Record and save all key synchronization parameters at the moment of closing, including: actual voltage difference, actual frequency difference, and actual phase angle difference; this is equivalent to taking a "snapshot" of the synchronization event at a critical moment. At the precise instant the circuit breaker's main contacts confirm physical closure, the system immediately records the final values ​​of all key synchronization parameters at that moment.

[0150] Record and save the core computational parameters used in this synchronization process, including at least the system latency used during prediction; with all the core parameters, technicians can clearly analyze the convergence process and health status of the adaptive correction algorithm.

[0151] Record the occurrence time of key events, including at least: the calculated optimal command issuance time and the actual physical closing time of the circuit breaker position node feedback; establish a timeline for the entire event, which can reflect the entire process of prediction, delay compensation and execution.

[0152] The final result of recording the closing time is determined, including whether it is a synchronous closing or an asynchronous closing.

[0153] The system records the execution status of the closing command, including whether the closing was successful or failed. If the closing failed, the corresponding fault classification label is recorded, which is linked to the aforementioned fault diagnosis mechanism: if the determination result is "closing failed", the record will also include the fault classification label generated by the diagnosis mechanism (e.g., "frequency slippage too fast"). This allows the final test report to directly associate the "result" with the "cause".

[0154] Example 6

[0155] This embodiment provides an instrument for performing the method described in any of the foregoing embodiments, comprising:

[0156] The signal acquisition unit connects the generator side and the grid side to acquire voltage waveforms in real time. Its main function is to capture the analog voltage waveforms from both the generator and grid sides in real time and convert them into digital signals that a processor can recognize and process. In its physical implementation, this unit typically includes a voltage transformer or high-impedance probe for safety isolation and voltage transformation, and an analog-to-digital converter (ADC) for converting continuous analog voltage signals into discrete digital sequences.

[0157] The memory is used to store instructions and data, including preset system latency times; it typically includes volatile and non-volatile memory. Its main functions are twofold: first, it stores the computer program instructions that implement all the methods described in this invention, including algorithms such as second-order dynamic prediction, adaptive latency correction, precondition judgment, fault diagnosis, and data archiving; second, it stores various types of data required during the computation process, such as various threshold parameters and learning rate boundary values ​​as fixed configurations, the initial system latency time obtained during the calibration phase, and the current system latency time and various temporary calculation results that are continuously updated during operation.

[0158] The processor, electrically connected to the memory and signal acquisition unit, is used to execute the methods described above; it is typically a digital signal processor (DSP), microcontroller (MCU), or embedded CPU. Its main responsibilities are: to fetch program instructions from the memory, receive digitized waveform data from the signal acquisition unit, and execute all complex mathematical operations and logical judgments at high speed, such as real-time calculation of the phase angle difference and its first and second derivatives, solving quadratic equations, performing linear interpolation calculations, and comparing parameters with thresholds. Finally, based on the comprehensive results of the algorithm, the processor determines a unique, microsecond-precise optimal time to issue the closing command.

[0159] The command output interface is used to issue closing commands to the circuit breaker control system based on the processor's calculations. Its main function is to convert the internal logic control signals issued by the processor into physical electrical signals that can reliably drive the external circuit breaker control system (such as the closing coil). In its physical implementation, this unit typically includes digital output ports and isolated drive circuits such as relays, optocouplers, or solid-state relays to ensure that the command signals can be transmitted accurately, reliably, and safely.

[0160] Example 7

[0161] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the monitoring method for synchronous grid connection and closing of a power system as described above.

[0162] Without loss of generality, computer-readable media can include computer storage media and communication media. Computer storage media includes volatile and non-volatile, removable and non-removable media implemented using any method or technology for storing information such as computer-readable instruction data structures, program modules, or other data. Computer storage media includes RAM, ROM, EPROM, EEPROM, flash memory or other solid-state storage technologies, CD-ROM, DVD or other optical storage, magnetic tape cassettes, magnetic tape, disk storage, or other magnetic storage devices. Of course, those skilled in the art will recognize that computer storage media are not limited to the above-mentioned types. The aforementioned system memories and mass storage devices can be collectively referred to as memory.

[0163] A computer program product includes a computer program / instructions that, when executed by a processor, implement the monitoring method for synchronous grid connection and closing of a power system as described above.

[0164] Computer program products include computer programs or instruction sets used to perform specific tasks or achieve specific functions. These programs or instructions are designed to be executed by a processor to implement a series of predefined steps or operations. The program product may be stored in various forms of computer storage media, such as memory, hard disks, solid-state drives, optical discs, or other forms of digital storage devices. It may exist in the form of compiled binary code or in the form of scripts or bytecode that can be executed by an interpreter. Through carefully designed algorithms and logical instructions, the program product enables the processor to process data in a specific order and manner, performing various functions such as data analysis, user interaction, and device control.

[0165] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0166] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0167] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above invention, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A method for monitoring power system synchronization and grid closing, characterized in that, The method comprises the following steps: Real-time acquisition of voltage waveforms on the generator side and the grid side; Real-time calculation of dynamic synchronization parameters between the generator side and the grid side based on the voltage waveforms, the dynamic synchronization parameters including phase angle difference and slip angle frequency; Obtaining system delay time, which is the time difference between the issuance of a closing instruction by a monitoring system synchronization device and the physical closing of a circuit breaker; According to the phase angle difference and the slip angle frequency, predicting a future synchronization time when the phase angle difference reaches a preset target value; Based on the future synchronization time and the system delay time, calculating an optimal closing instruction issuance time; Obtaining an actual instruction issuance time of the closing instruction issued by the monitoring system synchronization device; Comparing the optimal closing instruction issuance time with the actual instruction issuance time, if the time error is less than a set value, determining that the closing is synchronous; otherwise, determining that the closing is not synchronous.

2. The method of claim 1, wherein, The method for predicting the future synchronization time comprises: Get the current time t current Instantaneous phase difference Δθ(T) current Instantaneous slip angular frequency ω slip (t current and instantaneous slip angular acceleration α slip (t current ); Constructing a second order Taylor expansion of the phase angle difference as a function of time to predict the future phase angle difference Where Δt is the predicted time interval from the current time to the future synchronization time. Let Δθ(t current +Δt) = 0, and solve to obtain a mathematical solution; from the mathematical solution, screen and determine the smallest positive real solution as the final predicted time interval Δt; The future synchronization time instant t is calculated sync , t sync = t current + Δt.

3. The method of claim 1, wherein, The method further comprises the following steps: After the actual closing of the circuit breaker, measuring the actual phase angle difference at the closing moment; According to the deviation between the actual phase angle difference and the preset target value, updating the system delay time.

4. The method of claim 3, wherein the method further comprises: The method for updating the system delay time comprises: At the end of the kth synchronization test, based on the actual phase angle difference Δθ actual (k) and the actual slip angle frequency ω slip_actual (k) to calculate the instantaneous time error Computing error normalized amplitude where t errormax is a preset maximum valid error threshold value; Pre-set minimum learning rate α min and maximum learning rate α max , the learning rate α(k) of the kth update is calculated by linear interpolation method, α(k) = α min + (α max - α min )·η(k); The update obtains a new system delay time T delay (k+1) = T delay (k) + a(k) - t error (k), where T delay (k) is the system delay time of performing the kth synchronization test.

5. The method of claim 1, wherein, The method further comprises an initial system delay time calibration method for determining the initial value of the system delay time, the calibration method comprising: Calculate the single measurement delay corresponding to each test i: T measured (i) = t closure (i) - t command (i), where t command (i) is the time at which the command is issued in the i-th calibration test, t closure (i) is the time at which the physical closure of the circuit breaker is confirmed in the i-th calibration test; Conducting N independent calibration tests in succession, and obtaining an original sample set S after completing the N tests; Sorting the sample set S and calculating the first quartile Q1 and the third quartile Q3, and calculating the interquartile range IQR, IQR = Q3-Q1; Traverse each element T in the original sample set S measured (i), keep the elements satisfying Lower_Bound ≤ T measured (i) ≤ Upper_Bound, and store them in the new valid sample set S filtered , where Lower_Bound = Q1 - 1.5 · IQR is the lower bound of valid data, and Upper_Bound = Q3 + 1.5 · IQR is the upper bound of valid data. The arithmetic mean is taken over all elements in the effective sample set S filtered to obtain the initial system delay time where |S filtered | is the number of elements in the effective sample set.

6. The method of claim 3, wherein the method further comprises: Before the circuit breaker control system executes the closing instruction, performing precondition judgment, the method comprising: Real-time monitoring of the voltage difference ΔU and the frequency difference Δf between the generator side and the grid side; Judging whether the voltage difference ΔU is less than a preset voltage difference allowable threshold value; Judging whether the frequency difference Δf is less than a preset frequency difference allowable threshold value; If both are less than the preset allowable threshold value, executing the closing instruction; otherwise, terminating the execution.

7. The method of claim 6, wherein the method further comprises: If the execution of the closing instruction is terminated, the following steps are performed: Recording and saving the dynamic synchronization parameters within a specific time window before the abortion or failure, the dynamic synchronization parameters at least including the time series of the voltage difference, the frequency difference and the slip angle frequency; According to the captured time series data, performing the following logical judgment to determine the cause classification: If there is a continuous time period within the observation time window before the abortion or failure, the time length of which is greater than a preset frequency duration threshold value, and the absolute value of the slip angle frequency is always greater than a preset slip threshold value within the continuous time period, the cause classification is identified as the frequency slip being too fast; If a closing failure event occurs, and the absolute value of the instantaneous time error calculated from the actual phase angle difference and the actual slip angle frequency is greater than a preset delay error threshold value, the cause classification is identified as the system delay model mismatch. If there is a continuous time period in the observation time window before the synchronization process is aborted, the length of which is greater than a preset voltage duration threshold, and in which the absolute value of the voltage difference is always greater than a preset voltage difference threshold, then the cause classification is identified as voltage difference duration over limit.

8. The method of claim 1, wherein, After each monitoring process, a structured test record is generated, the method comprising: capturing and storing time series data of key dynamic synchronization parameters within a time window around the closing event, the time window covering at least from the actual command time / optimal command time to the actual physical closing time of the circuit breaker, and the time series data including at least the data of the change of the phase angle difference over time; recording and saving all key synchronization parameters at the closing moment, including the actual voltage difference, the actual frequency difference and the actual phase angle difference; recording and saving the core calculation parameters used in the execution of the synchronization process, including at least the system delay time used in the prediction; recording the occurrence time of key events, including at least the calculated optimal command time, the actual command time and the actual physical closing time of the circuit breaker position node feedback; recording the final result judgment of the closing time, including synchronous closing or non-synchronous closing; recording the closing instruction execution, including closing success or closing failure, and if the closing fails, recording the corresponding fault classification label.

9. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 8. The computer program is executed by the processor to realize the monitoring method of the power system synchronous grid closing as claimed in any one of claims 1-8.

10. A computer program product comprising computer programs / instructions, characterized in that, The computer program / instruction is executed by the processor to realize the monitoring method of the power system synchronous grid closing as claimed in any one of claims 1-8.

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