A substation pole contact resistance state evaluation method and system

Abstract

A substation knife switch contact resistance state evaluation method and system, the method comprises the following steps: collecting the current and temperature rise of the to-be-tested knife switch, and constructing a synchronous data set; defining a stable state and an out-of-control state of the contact resistance, and constructing an empirical estimation model of the knife switch temperature rise and current by taking the contact resistance as an intermediate variable; using multiple groups of sub-samples in the synchronous data set to estimate the parameters of the empirical estimation model, and obtaining a model parameter set sequence; using a hypothesis testing method to test the stability of the model parameter set sequence, and if the model parameter set sequence is stable, evaluating that the contact resistance is in a stable state, otherwise evaluating that the contact resistance is in an out-of-control state. The present application can accurately and quickly judge whether an additional resistance appears under the premise of uninterrupted power supply, and further evaluate the contact resistance state of the knife switch, predict the risk of heat loss of control, and provide a reference for subsequent optimization of maintenance strategy.

Description

Technical Field

[0001] This invention belongs to the field of substation maintenance technology, and more specifically, relates to a method and system for assessing the contact resistance status of substation disconnectors. Background Technology

[0002] A disconnecting switch (or disconnecting circuit breaker) is a crucial primary device in a substation. It is a switching device used for isolating power supplies, performing switching operations, connecting and disconnecting low-current circuits, and lacks arc-extinguishing capabilities. When open, the disconnecting switch has a specified insulation distance between its contacts and a clear disconnection indicator. When closed, it can carry current under normal circuit conditions, as well as current under abnormal conditions such as short circuits for a specified time, making it vital for the reliability of the power grid.

[0003] During operation, the contact resistance between the moving and stationary contacts of the disconnector, as well as the conductive components, generate heat due to the large current flowing through them. For a long time, the condition of the disconnector has been judged by its temperature. For example, according to Appendix A, Table A.1 of DL / T 664-2008 "Guidelines for Infrared Diagnosis of Live Equipment," the diagnostic criteria for heat generation are: when the hot spot temperature in the thermal image is higher than 110℃ or the relative temperature difference is not less than 95%, it is considered a critical defect. When the temperature of the contacts and equipment clamps exceeds 130℃ or the relative temperature difference is not less than 95%, it is generally recommended to immediately shut down the power for maintenance.

[0004] However, the reality is far more complex. Sometimes, when disconnectors overheat in areas with critical loads, the cost of power outages for maintenance is extremely high, making it difficult to unconditionally shut down for maintenance as soon as the temperature rises. For example, during the peak summer power supply period, even if the disconnectors of the main transformer in a 500kV substation were overheating and approaching the point of requiring a power outage for maintenance, it was impossible to immediately shut down for maintenance to ensure the reliability of the power grid during this period. In this situation, the power grid maintenance department faced a dilemma: risking continued operation or reluctantly shutting down for maintenance.

[0005] In view of the above situation, when the temperature of the disconnector approaches the critical value, if a certain method can be used to predict the state of the disconnector, such as but not limited to the contact resistance value or its changing trend, it will be of great significance for whether to shut down the power and the corresponding maintenance plan. The existing methods to solve this problem include (1) temperature measurement method: infrared temperature measurement or online monitoring to obtain the temperature of the disconnector contacts or heating components, and judge the state of the disconnector based on the temperature. However, the reasons for the temperature rise are very complicated, and it is impossible to distinguish whether the heating is caused by the increase of contact resistance or other reasons, nor can it estimate the changing trend of the disconnector contact resistance; (2) analytical method: using physical quantities such as temperature and current, the contact resistance is derived by empirical algebraic formulas. However, the relationship between temperature, current and contact resistance is very complicated. Resistance loss, eddy current loss and various heat dissipation processes should be considered. Algebraic equations cannot be calculated, and empirical algebraic calculation formulas have a large error; (3) direct measurement method: using a small resistance measuring device to directly measure the contact resistance of the disconnector. However, at present, micro-ohm level resistance measurement is only applicable to power outage measurement. When the power is heated, it is impossible to shut down the power, so this method is not applicable.

[0006] Existing technology document 1 (CN118777853A) discloses an online monitoring method for the contact resistance of high-voltage live disconnect switches based on a support vector machine model. The shortcomings of existing technology document 1 are that it assumes that the multi-source measurement data are synchronous data from the same moment, which deviates from the actual collected data. Furthermore, it requires parameters such as temperature to remain stable over a long timescale, making it difficult to adapt to the dynamic changes of various parameters under high-temperature and high-load conditions. In addition, existing technology document 1 uses complex steady-state thermal analysis and regression prediction algorithms to directly calculate the contact resistance value, requiring significant computational power and resulting in slow calculation speed. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method and system for assessing the contact resistance status of substation disconnectors, offering a reference for power grid maintenance departments in formulating maintenance strategies.

[0008] The present invention adopts the following technical solution.

[0009] The first aspect of the present invention provides a method for assessing the contact resistance status of a substation disconnector, comprising the following steps: Step 1: Collect the current and temperature rise of the switch under test and construct a synchronous dataset; Step 2: Define the steady state and runaway state of the contact resistance, and construct an empirical estimation model of the temperature rise and current of the disconnector using the contact resistance as an intermediate quantity. Step 3: Use multiple subsamples from the synchronized dataset to estimate the parameters of the empirical estimation model and obtain the model parameter set sequence; Step 4: Use hypothesis testing to test the stability of the model parameter set sequence. If the model parameter set sequence is stable, the contact resistance is evaluated as being in a stable state; otherwise, the contact resistance is evaluated as being in an out-of-control state.

[0010] Preferably, step 1 includes: Step 1.1: Collect one current data point within each time period t, where t contains multiple 1-minute intervals; Step 1.2: Collect temperature data of the knife edge or lap surface of the switch multiple times every minute within time period t and calculate the temperature rise. The number of temperature rise data collected every minute is a dynamic value. Step 1.3: Construct a synchronous dataset based on the current data, and integrate the temperature rise data into a dataset with the same dimensions as the current data.

[0011] Preferably, step 1.3 further includes: If a temperature rise data value is greater than a set multiple of the temperature rise data values ​​before and after it, or if a set number of consecutive temperature rise data values ​​are all zero, then it is considered invalid temperature rise data and is discarded. The remaining temperature rise data after discarding invalid temperature rise data... n The temperature rise data for each time period t are averaged and integrated, and expressed as follows:

[0012] In the formula, For the first n The combined value of temperature rise data for each time period t. For the first n The first temperature rise data obtained in the first minute within a time period t. For the first n The last temperature rise data obtained in the first minute within a time period t. For the first n The first temperature rise data obtained in the last minute of time period t. For the first n The last temperature rise data obtained in the last minute of each time period t. For the first n The number of temperature rise data points collected in the first minute within a time period t. For the first n The number of temperature rise data points collected in the last minute of each time period t.

[0013] Preferably, if the first n If all temperature rise data for time period t are invalid, then the combined value of temperature rise data from two adjacent time periods t will be used. Construct a triple linear interpolation calculation for the first n Combined value of temperature rise data for each time period t It can be expressed by the following formula:

[0014] In the formula, This is the first interpolation. This is the second interpolation. This is the third interpolation.

[0015] Preferably, in step 2, defining the steady state and runaway state of the contact resistance includes: The contact resistance undergoes a reversible change in resistance value as the temperature and current increase. When the temperature and current decrease, the contact resistance can return to its original state. At this point, the contact resistance is defined as being in a steady state. Contact resistance undergoes irreversible changes as temperature and current increase. When temperature and current decrease, the contact resistance cannot return to its original state; instead, an additional resistance is added. At this point, the contact resistance is defined as being in an uncontrolled state.

[0016] Preferably, in step 2, the temperature rise of the disconnect switch... T With current The empirical estimation model is expressed by the following formula:

[0017] In the formula, For current term parameters, Let be a constant term parameter, and satisfy:

[0018]

[0019] In the formula, For contact resistance, For quadratic parameters, The first intercept parameter, For correlation parameters, This is the second intercept parameter.

[0020] Preferably, step 3 includes: Step 3.1: Starting from the first data in the synchronous dataset, use a rolling data window to extract the first subsample of the synchronous dataset, perform parameter estimation on the empirical estimation model of switch temperature rise and current, and obtain the model parameter set based on the first subsample. Step 3.2: Move the data window backward to generate the next subsample in sequence, and obtain the model parameter set based on different subsamples in sequence until the data window covers the last data in the synchronous dataset, and obtain the model parameter set based on the last subsample. All model parameter sets constitute the model parameter set sequence.

[0021] Preferably, in step 4, a sequence of current term parameter sets is used. The stability represents the stability of the model parameter set sequence, and the stability of the current term parameter set sequence is determined according to the following criterion: A sliding t-test is performed on the current term parameter set sequence. If all test results are significant and the following condition is met, the current term parameter set sequence is considered stable, and the condition is expressed by the following formula:

[0022] In the formula, This represents the current term parameters estimated based on the first subsample. This represents the current term parameters estimated based on the second subsample. Indicates based on the first P The current term parameters obtained from the subsample estimation Indicates based on the first i The current term parameters obtained from the subsample estimation P This represents the number of parameters for the current term.

[0023] Preferably, step 4 further includes: Based on the contact resistance condition assessment results, the temperature rise is estimated, and then the optimal maintenance strategy is selected. When the contact resistance is stable, the model parameters are re-estimated using full sample data from the synchronous dataset, and the future temperature rise is predicted in conjunction with the future current value. If the estimated temperature rise is greater than 130 degrees Celsius, the maintenance strategy is to prepare for emergency power outage repairs in advance. If the estimated temperature rise is greater than 110 degrees Celsius but not greater than 130 degrees Celsius, the maintenance strategy is to prepare for emergency repairs in advance and deploy online monitoring devices in conjunction with power outage work. If the estimated temperature rise is greater than 95 degrees Celsius but not greater than 100 degrees Celsius, the maintenance strategy is to increase the intensity of daily inspections. When the contact resistance is out of control, the maintenance strategy is to immediately prepare for emergency power outage repairs.

[0024] A second aspect of the present invention provides a substation disconnector contact resistance status assessment system, wherein the substation disconnector contact resistance status assessment method comprises: The data construction module is used to collect the current and temperature rise of the switch under test and build a synchronous dataset; The empirical estimation module is used to define the steady-state and runaway state of the contact resistance, and to build an empirical estimation model of the temperature rise and current of the disconnector using the contact resistance as an intermediate quantity. The parameter estimation module is used to estimate the parameters of the empirical estimation model using multiple subsamples in the synchronous dataset, and obtain the model parameter set sequence. The state assessment module is used to test the stability of the model parameter set sequence using hypothesis testing methods. If the model parameter set sequence is stable, the contact resistance is assessed as being in a stable state; otherwise, the contact resistance is assessed as being in an out-of-control state.

[0025] A third aspect of the present invention provides an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the computer program, when loaded onto the processor, implements the substation disconnector contact resistance status assessment method.

[0026] A fourth aspect of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the substation disconnector contact resistance status assessment method.

[0027] Compared with the prior art, the beneficial effects of the present invention include at least the following: 1. The substation disconnector contact resistance status assessment method and system of the present invention, by measuring temperature rise and current and using contact resistance as an intermediate quantity to estimate model parameters, can accurately and quickly determine whether additional resistance has occurred without interrupting power supply, thereby assessing the contact resistance status of the disconnector, predicting the risk of thermal runaway, and providing a reference for subsequent optimization of maintenance strategies.

[0028] 2. By constructing a synchronized dataset, this invention can time-align data from different sources and at different frequencies, which is more in line with actual application scenarios.

[0029] 3. This invention adopts an empirical estimation model of the temperature rise and current of the switch, using contact resistance as an intermediate quantity, without the need to directly calculate the contact resistance value, thus reducing the amount of calculation for simulating losses and heat dissipation processes, and avoiding errors in empirical algebraic calculation formulas.

[0030] 4. This invention selects multiple different sub-samples from a synchronous dataset to dynamically evaluate the contact resistance status, taking into account the unstable characteristics of real-time changes in parameters such as temperature, thereby further increasing the real-time performance and accuracy of the evaluation results. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the main electrical wiring of a substation provided according to an embodiment of the present invention; Figure 2 This is a flowchart of a method for assessing the contact resistance status of substation disconnectors according to an embodiment of the present invention; Figure 3 This is a schematic diagram of triple linear interpolation calculation provided according to an embodiment of the present invention. Detailed Implementation

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

[0033] like Figure 1 As shown, the main electrical wiring of a substation includes busbars, disconnectors, circuit breakers, and transformers. During the peak summer power supply period, the incoming disconnector 25023 of the No. 2 main transformer reached a temperature of 105℃. According to Appendix A, Table A.1 of DL / T 664-2008 "Guidelines for Infrared Diagnosis of Live Equipment," this temperature reading indicates the substation is approaching the point of needing to shut down for maintenance. If conditions permit, maintenance should be carried out, but due to difficulties in adjusting operating modes during the power supply period, this is not feasible. If the temperature rises to 130℃ or higher, continuing operation risks equipment damage, while a forced shutdown would reduce grid reliability. Faced with this dilemma, a method for predicting disconnector status is urgently needed. This method could assess the stability of contact resistance when the disconnector's temperature approaches the critical value, providing a reference for the grid maintenance department to decide whether to shut down and to formulate maintenance strategies.

[0034] like Figure 2 As shown, Embodiment 1 of the present invention provides a method for evaluating the contact resistance status of a substation disconnector. It is worth noting that in Embodiment 1, the temperatures of other conductive components are assumed to be normal. Furthermore, those skilled in the art will understand that the contact resistance of a disconnector refers to the contact resistance between the moving and stationary contacts of the disconnector. The method includes the following steps: Step 1: Collect current and temperature data of the switch under test, calculate the temperature rise value through the temperature value, and construct a synchronous dataset.

[0035] In a preferred but non-limiting embodiment of the present invention, step 1 specifically includes: Step 1.1: Collect current data from one site within each time period t to obtain a current dataset. Where t contains multiple 1-minute intervals, This represents the first current data point, i.e., the current collected in the first time period t. This indicates the second current data point. This indicates the third current data point. Indicates the first n The current data point, i.e. the th current data point n The current collected in each time period t.

[0036] More preferably, current data is obtained through an automated plant terminal system, and its validity is checked. Specifically, considering the large fluctuations in current during actual operation, if the fluctuations in the collected current data are consistent with reality, it is determined to be valid current data; if there are extremely unreasonable single-point large numbers or continuous missing data, it is determined to be invalid current data and discarded.

[0037] Step 1.2: Within time period t, the temperature data of the currently monitored switch component (e.g., the blade edge or lap joint) is collected multiple times in real time every minute using a temperature measuring device, and the delta value of the temperature change is calculated as the temperature rise. The temperature rise data obtainable per minute is... ,in, Indicates the first m The first temperature rise data obtained in minutes Indicates the first m The minute obtained N m One temperature rise data point, N m For the first m The number of temperature rise data collected per minute N m Values ​​are dynamically retrieved every minute.

[0038] More preferably, temperature data is obtained through a wireless temperature monitoring device.

[0039] It is worth noting that the current and temperature data come from different systems. Typically, the sampling granularity of the two data sets is mismatched, resulting in data asynchrony. For example, the sampling frequency of current data is one data point every 5 minutes, while the sampling frequency of temperature rise data varies from 2 to 4 data points per minute. Asynchronous data cannot be directly used as input data for subsequent calculations.

[0040] Step 1.3: Construct a synchronization dataset based on data with lower sampling frequencies, and integrate data with higher sampling frequencies into a dataset with the same dimensions as the data with lower sampling frequencies. Taking the case of low sampling frequency for current data as an example, the synchronization dataset is represented as follows: ,in This represents the aggregated value of temperature rise data for the first time period t. This represents the aggregated value of the temperature rise data for the second time period t. This represents the aggregated value of the temperature rise data for the third time period t. Indicates the first n The combined value of temperature rise data for each time period t.

[0041] More preferably, considering the continuous nature of temperature rise changes and the low probability of abrupt changes, if a certain temperature rise data value is tens of times larger than the temperature rise data values ​​before and after it, causing data overflow, or if the temperature rise data value is consecutively zero, it is considered invalid temperature rise data and is removed. The remaining temperature rise data after removing invalid temperature rise data... n The effective temperature rise data for each time period t are averaged and integrated, and expressed as follows:

[0042] In the formula, For the first n The combined value of temperature rise data for each time period t.

[0043] More preferably, if the first n If all temperature rise data for time period t are invalid, then the combined value of temperature rise data from two adjacent time periods t will be used. Construct a triple linear interpolation calculation for the first n Combined value of temperature rise data for each time period t ,like Figure 3 As shown, it is expressed by the following formula:

[0044] In the formula, This is the first interpolation. This is the second interpolation. This is the third interpolation.

[0045] Step 2: Define the steady-state and runaway state of the contact resistance, and construct an empirical estimation model of the temperature rise and current of the disconnector using the contact resistance as an intermediate quantity.

[0046] In a preferred but non-limiting embodiment of the present invention, step 2 specifically includes: Step 2.1: Define the contact resistance state of the disconnector by analyzing the resistance change pattern. Specifically, let the contact resistance of the disconnector contacts be... Based on the actual state of the disconnector contacts, The increase can occur in two ways: (1) If the state of the disconnector contacts does not change, the contact resistance As temperature and current increase, the resistance changes accordingly; this change is reversible. When temperature and current decrease, the contact resistance... It can be restored to its original state, at which point the contact resistance of the switch is defined as being in a stable state.

[0047] (2) If the condition of the disconnector contacts has changed, such as due to surface oxidation, the contact resistance will be reduced. A significant increase in resistance is accompanied by a sharp change in resistance due to rising temperature and increased current. This change is generally irreversible. When the temperature and current decrease, the contact resistance... It cannot be restored to its original state; instead, an additional resistor is added. At this point, the contact resistance of the disconnect switch is defined as being out of control.

[0048] Understandably, the second scenario is more serious, such as when additional resistance is determined to have occurred. When the load increases and the current rises, the contacts are prone to overheating, and there is a high probability that contact erosion will occur. This can be addressed by determining if overheating is present. It can effectively predict the state of the knife switch contacts.

[0049] Step 2.2, contact resistance With current The relationship is denoted as In a further preferred but non-limiting embodiment of the invention, it is set that... For a continuous function, the function The domain is defined as [100, 1500]. Since the probability of resistance deterioration due to low current is extremely low, 100A is taken as the lower bound of the value range.

[0050] In a further preferred but non-limiting embodiment of the invention, the empirical estimation model is instantiated based on field test data. The field test data shows that the contact resistance and current have a quadratic function relationship. It is assumed that... Since the contact resistance is a quadratic function, the relationship between the contact resistance and the current is as follows:

[0051] In the formula, For quadratic parameters, This is the first intercept parameter.

[0052] Step 2.3, increase the temperature of the disconnect switch. T With contact resistance The relationship is denoted as In a further preferred but non-limiting embodiment of the invention, it is set that... For a continuous function, the function The value range is [25, 130]. ​​Since it is no longer meaningful to evaluate above 130℃, it is necessary to shut down the power for emergency repair. Therefore, 130℃ is taken as the upper limit of the value range. Considering the peak summer temperature, the probability of resistance deterioration when the temperature of the disconnector contact is lower than the air temperature is extremely low. Therefore, 25℃ is taken as the lower limit of the value range.

[0053] In a further preferred but non-limiting embodiment of the present invention, the empirical estimation model is instantiated based on field test data. The field test data shows that there is a strong linear correlation between contact resistance and the temperature rise of the disconnect switch. It is assumed that... If the function is linear, then the relationship between temperature rise and contact resistance is as follows:

[0054] In the formula, For correlation parameters, This is the second intercept parameter.

[0055] Step 2.4: Substitute the relationship between contact resistance and current from Step 2.2 into the relationship between temperature rise and contact resistance from Step 2.3 to obtain the relationship between temperature rise and current, expressed as follows:

[0056] Step 2.5, let These are the parameters for the first model, i.e., the parameters for the current term. If the parameters are the second model parameters, i.e., the constant term parameters, then the empirical estimation model for the temperature rise and current of the disconnector is expressed by the following formula:

[0057] Understandably, since temperature rise and current data are available, parameters can be fitted. A and B The value of . According to the definition of the contact resistance state of the disconnector in step 2.1, if the contact condition of the disconnector does not deteriorate, the contact resistance should maintain a functional relationship with temperature and current, that is , If unchanged, then the parameter A and B It is stable, remaining constant within the allowable error range. If the condition deteriorates, additional resistance appears. ,but ,parameter A and B Mutations can occur.

[0058] Step 3: Using multiple subsamples from the synchronous dataset in Step 1, perform parameter estimation on the empirical estimation model of switch temperature rise and current obtained in Step 2 to obtain the model parameter set sequence.

[0059] In a preferred but non-limiting embodiment of the present invention, a rolling data window is used to extract different sub-samples of the synchronous dataset obtained in step 1, and to estimate the parameters in the empirical estimation model of the switch temperature rise and current. Step 3 specifically includes: Step 3.1: Starting from the first data point in the synchronized dataset, a rolling data window is used to extract a subsample from the synchronized dataset. The subsample extracted by the first data window is denoted as subsample 1. Subsample 1 is used to estimate the parameters of the empirical estimation model for the temperature rise and current of the disconnect switch, thus obtaining the model parameter set based on subsample 1. .

[0060] Understandably, extracting subsamples by using a rolling data window allows for segmentation of a synchronous dataset containing a large amount of data as needed, making subsequent parameter evaluation results smoother and further increasing the accuracy of contact resistance evaluation.

[0061] Step 3.2: Move the data window backward to generate the next subsample in sequence, and obtain subsample-based data one by one. i Model parameter set This continues until the data window covers the last data point in the synchronized dataset, obtaining the model parameter set based on the last subsample. That is, to obtain the model parameter set sequence , P This represents the number of subsamples.

[0062] Understandably, each model parameter set The data includes model parameters estimated using different temperature rise and current data, i.e. Each model parameter in the model parameter set sequence contains P The parameter estimation results are as follows: ,if P indivual If the statistical difference between them is very small, then they can be identified as the corresponding current term parameters. A It is stable, constant term parameter B The same logic applies to determining stability.

[0063] It is worth noting that those skilled in the art can also use other existing empirical estimation models to estimate parameters and obtain a model parameter set containing multiple parameters, or use other common methods to screen subsamples, such as expert evaluation and random selection. Based on the spirit of this invention, all of these should fall within the protection scope of this invention.

[0064] Step 4: Use hypothesis testing to test the stability of the model parameter set sequence. If the model parameter set sequence is stable, the contact resistance is evaluated as being in a stable state; otherwise, the contact resistance is evaluated as being in an out-of-control state.

[0065] In a preferred but non-limiting embodiment of the invention, the current term parameters in the model are estimated empirically. A As a representative parameter, the corresponding current term parameter set sequence is used. The stability represents the stability of the model parameter set sequence. A sliding t-test is performed on the current term parameter set sequence. If all test results are significant and the following conditions are met, the current term parameter set sequence is considered stable, and the contact resistance of the switch is evaluated to be in a stable state, which corresponds to case (1) in step 2.1. The condition is expressed by the following formula:

[0066] In the formula, This represents the current term parameters estimated based on the first subsample. This represents the current term parameters estimated based on the second subsample. Indicates based on the first P The current term parameters obtained from the subsample estimation Indicates based on the first i The current term parameters obtained from the subsample estimation P The number of subsamples, i.e., the sequence of current term parameter sets. The number of parameters in the current term.

[0067] Understandably, considering the current term parameters A As coefficients of the current term in an empirical estimation model, their stability is higher than that of the constant term parameters, which are considered constant terms. B More importantly, the constant term parameter B The stability is affected by the current term parameter A For engineering simplification, only the current term parameter is selected to account for the impact of the estimated values. A Using one parameter as a representative parameter further improves the evaluation speed.

[0068] In a preferred but non-limiting embodiment of the present invention, step 4 further includes: estimating the temperature rise based on the contact resistance condition assessment results. T This allows for the selection of the optimal maintenance strategy, specifically including: When the contact resistance of the disconnect switch is stable, corresponding to case (1) in step 2.1, the contact resistance is considered to be stable. The variation pattern is stable, so the model parameters are re-estimated using the full sample data from the synchronization dataset in step 1. A and B And combined with future current values, predict future temperature rise. T If the estimated temperature rise is greater than 130 degrees Celsius, the maintenance strategy is to prepare for an emergency power outage for repairs in advance; if the estimated temperature rise is greater than 110 degrees Celsius but not greater than 130 degrees Celsius, the maintenance strategy is to prepare for repairs in advance in conjunction with the power outage work and deploy online monitoring devices; if the estimated temperature rise is greater than 95 degrees Celsius but not greater than 100 degrees Celsius, the maintenance strategy is to increase the intensity of daily inspections.

[0069] When the contact resistance of the switch is out of control, which corresponds to the situation in step 2.1 (2), it is considered that if the current increases further, the risk of overheating exceeding 130 degrees Celsius is extremely high. The maintenance strategy is to immediately prepare for emergency power outage repair.

[0070] Embodiment 2 of the present invention provides a substation disconnector contact resistance status assessment system, which, when running the substation disconnector contact resistance status assessment method described in Embodiment 1, includes: The data construction module is used to collect the current and temperature rise of the switch under test and build a synchronous dataset; The empirical estimation module is used to define the steady-state and runaway state of the contact resistance, and to build an empirical estimation model of the temperature rise and current of the disconnector using the contact resistance as an intermediate quantity. The parameter estimation module is used to estimate the parameters of the empirical estimation model using multiple subsamples in the synchronous dataset, and obtain the model parameter set sequence. The state assessment module is used to test the stability of the model parameter set sequence using hypothesis testing methods. If the model parameter set sequence is stable, the contact resistance is assessed as being in a stable state; otherwise, the contact resistance is assessed as being in an out-of-control state.

[0071] Embodiment 3 of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is loaded into the processor, it implements the substation disconnector contact resistance status assessment method according to Embodiment 1.

[0072] Embodiment 4 of the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the substation disconnector contact resistance status assessment method according to Embodiment 1.

[0073] To more clearly illustrate the technical solution of the present invention and its beneficial technical effects, an application example of implementing the present invention is described below.

[0074] The method for assessing the contact resistance status of substation disconnectors as described in Embodiment 1 of this invention is illustrated using data from a 500kV substation in the Jiangsu power grid. Specifically, it includes: Current data was collected at 5-minute intervals, resulting in 288 current data points throughout the day. The sampling frequency for temperature rise data calculated from measured temperature data varies from 2 to 4 data points per minute, resulting in a total of 4,000 temperature rise data points per day. This indicates a mismatch in data sampling granularity.

[0075] Synchronization data should be based on current data to construct a synchronization dataset, and temperature rise data should be integrated as follows:

[0076] Other times The calculation formula is similar, such as for the 6th point. If no valid temperature data is available within 5 minutes, then follow the method in step 1.3 and utilize the data from before and after the test. Then, construct a triple linear interpolation. This yields the synchronized dataset:

[0077] By using a rolling data window, different data subsamples can be obtained. If there are 412 sets of data in the synchronous dataset, then 125 subsamples can be obtained.

[0078] Taking the first to the 288th data points in the dataset, i.e., data from one day, as a subsample, denoted as subsample 1, and then... Perform parameter estimation to obtain the model parameter set based on subsample 1. .

[0079] Then, the data window is moved to extract data from the 2nd to the 289th data point, and the model parameter set based on subsample 2 is calculated. , and obtain subsamples in sequence i Model parameter set This continues until the data window covers data points 125 to 412, obtaining the model parameter set based on subsample 125. That is, to obtain the model parameter set sequence. .

[0080] Each There are two types of model parameters, namely... At this point, 125 parameter estimates can be obtained for each model parameter, namely:

[0081] The sliding t-test showed that all model parameters were significant and satisfied the following:

[0082] Therefore, the contact resistance of the disconnector is considered stable. A new estimate is made using the full sample data. By using the parameters of A and B and the future current value, the temperature rise T is estimated, and the optimal maintenance strategy is selected accordingly.

[0083] Compared with the prior art, the beneficial effects of the present invention include at least the following: 1. The substation disconnector contact resistance status assessment method and system of the present invention, by measuring temperature rise and current and using contact resistance as an intermediate quantity to estimate model parameters, can accurately and quickly determine whether additional resistance has occurred without interrupting power supply, thereby assessing the contact resistance status of the disconnector, predicting the risk of thermal runaway, and providing a reference for subsequent optimization of maintenance strategies.

[0084] 2. By constructing a synchronized dataset, this invention can time-align data from different sources and at different frequencies, which is more in line with actual application scenarios.

[0085] 3. This invention adopts an empirical estimation model of the temperature rise and current of the switch, using contact resistance as an intermediate quantity, without the need to directly calculate the contact resistance value, thus reducing the amount of calculation for simulating losses and heat dissipation processes, and avoiding errors in empirical algebraic calculation formulas.

[0086] 4. This invention selects multiple different sub-samples from a synchronous dataset to dynamically evaluate the contact resistance status, taking into account the unstable characteristics of real-time changes in parameters such as temperature, thereby further increasing the real-time performance and accuracy of the evaluation results.

[0087] It is worth noting that in the embodiments of the present invention, "steps + numbers" is only an expression for clearly describing a specific implementation method of a substation disconnector contact resistance status assessment method, and not an absolute restriction on the order of the steps. Under the guidance of the core concept of the present invention, changing the order of these steps to obtain the same or similar technical effects all fall within the scope of the present invention.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A method for assessing the contact resistance of a substation disconnector, characterized in that, Includes the following steps: Step 1: Collect the current and temperature rise of the switch under test and construct a synchronous dataset; Step 2: Define the steady state and runaway state of the contact resistance, and construct an empirical estimation model of the temperature rise and current of the disconnector using the contact resistance as an intermediate quantity. Step 3: Use multiple subsamples from the synchronized dataset to estimate the parameters of the empirical estimation model and obtain the model parameter set sequence; Step 4: Use hypothesis testing to test the stability of the model parameter set sequence. If the model parameter set sequence is stable, the contact resistance is evaluated as being in a stable state; otherwise, the contact resistance is evaluated as being in an out-of-control state.

2. The method for assessing the contact resistance of substation disconnectors as described in claim 1, characterized in that: Step 1 includes: Step 1.1: Collect one current data point within each time period t, where t contains multiple 1-minute intervals; Step 1.2: Collect temperature data of the knife edge or lap surface of the switch multiple times every minute within time period t and calculate the temperature rise. The number of temperature rise data collected every minute is a dynamic value. Step 1.3: Construct a synchronous dataset based on the current data, and integrate the temperature rise data into a dataset with the same dimensions as the current data.

3. The method for assessing the contact resistance status of substation disconnectors as described in claim 2, characterized in that: Step 1.3 also includes: If a temperature rise data value is greater than a set multiple of the temperature rise data values ​​before and after it, or if a set number of consecutive temperature rise data values ​​are all zero, then it is considered invalid temperature rise data and is discarded. The remaining temperature rise data after discarding invalid temperature rise data... n The temperature rise data for each time period t are averaged and integrated, and expressed as follows: In the formula, For the first n The combined value of temperature rise data for each time period t. For the first n The first temperature rise data obtained in the first minute within a time period t. For the first n The last temperature rise data obtained in the first minute within a time period t. For the first n The first temperature rise data obtained in the last minute of time period t. For the first n The last temperature rise data obtained in the last minute of each time period t. For the first n The number of temperature rise data points collected in the first minute within a time period t. For the first n The number of temperature rise data points collected in the last minute of each time period t.

4. The method for assessing the contact resistance of substation disconnectors as described in claim 3, characterized in that: If the n If all temperature rise data for time period t are invalid, then the combined value of temperature rise data from two adjacent time periods t will be used. Construct a triple linear interpolation calculation for the first n Combined value of temperature rise data for each time period t It can be expressed by the following formula: In the formula, This is the first interpolation. This is the second interpolation. This is the third interpolation.

5. The method for assessing the contact resistance status of substation disconnectors as described in claim 1, characterized in that: In step 2, the steady-state and runaway states of the contact resistance are defined as follows: The contact resistance undergoes a reversible change as the temperature and current increase. When the temperature and current decrease, the contact resistance can return to its original state. At this point, the contact resistance is defined as being in a steady state. Contact resistance undergoes irreversible changes as temperature and current increase. When temperature and current decrease, the contact resistance cannot return to its original state; instead, an additional resistance is added. At this point, the contact resistance is defined as being in an uncontrolled state.

6. The method for assessing the contact resistance of substation disconnectors as described in claim 1, characterized in that: In step 2, the temperature rise of the disconnect switch T With current The empirical estimation model is expressed by the following formula: In the formula, For current term parameters, Let be a constant term parameter, and satisfy: In the formula, For contact resistance, For quadratic parameters, The first intercept parameter, For correlation parameters, This is the second intercept parameter.

7. The method for assessing the contact resistance of substation disconnectors as described in claim 1, characterized in that: Step 3 includes: Step 3.1: Starting from the first data in the synchronous dataset, use a rolling data window to extract the first subsample of the synchronous dataset, perform parameter estimation on the empirical estimation model of switch temperature rise and current, and obtain the model parameter set based on the first subsample. Step 3.2: Move the data window backward to generate the next subsample in sequence, and obtain the model parameter set based on different subsamples in sequence until the data window covers the last data in the synchronous dataset, and obtain the model parameter set based on the last subsample. All model parameter sets constitute the model parameter set sequence.

8. The method for assessing the contact resistance status of substation disconnectors as described in claim 7, characterized in that: In step 4, the current term parameter set sequence is used. The stability represents the stability of the model parameter set sequence, and the stability of the current term parameter set sequence is determined according to the following criterion: A sliding t-test is performed on the current term parameter set sequence. If all test results are significant and the following condition is met, the current term parameter set sequence is considered stable, and the condition is expressed by the following formula: In the formula, This represents the current term parameters estimated based on the first subsample. This represents the current term parameters estimated based on the second subsample. Indicates based on the first P The current term parameters obtained from the subsample estimation Indicates based on the first i The current term parameters obtained from the subsample estimation P This represents the number of parameters for the current term.

9. The method for assessing the contact resistance of substation disconnectors as described in claim 1, characterized in that: Step 4 also includes: Based on the contact resistance condition assessment results, the temperature rise is estimated, and then the optimal maintenance strategy is selected. When the contact resistance is stable, the model parameters are re-estimated using full sample data from the synchronous dataset, and the future temperature rise is estimated in conjunction with the future current value. If the estimated temperature rise is greater than 130 degrees Celsius, the maintenance strategy is to prepare for emergency power outage repairs in advance. If the estimated temperature rise is greater than 110 degrees Celsius but not greater than 130 degrees Celsius, the maintenance strategy is to prepare for emergency repairs in advance and deploy online monitoring devices in conjunction with power outage work. If the estimated temperature rise is greater than 95 degrees Celsius but not greater than 100 degrees Celsius, the maintenance strategy is to increase the intensity of daily inspections. When the contact resistance is out of control, the maintenance strategy is to immediately prepare for emergency power outage repairs.

10. A substation disconnector contact resistance condition assessment system, operating the substation disconnector contact resistance condition assessment method as described in any one of claims 1-9, characterized in that, include: The data construction module is used to collect the current and temperature rise of the switch under test and build a synchronous dataset; The empirical estimation module is used to define the steady-state and runaway state of the contact resistance, and to build an empirical estimation model of the temperature rise and current of the disconnector using the contact resistance as an intermediate quantity. The parameter estimation module is used to estimate the parameters of the empirical estimation model using multiple subsamples in the synchronous dataset, and obtain the model parameter set sequence. The state assessment module is used to test the stability of the model parameter set sequence using hypothesis testing methods. If the model parameter set sequence is stable, the contact resistance is assessed as being in a stable state; otherwise, the contact resistance is assessed as being in an out-of-control state.

11. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the computer program is loaded into the processor, it implements the substation disconnector contact resistance status assessment method as described in any one of claims 1-9.

12. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by the processor, it implements the substation disconnector contact resistance status assessment method as described in any one of claims 1-9.

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