An electric power fitting contact resistance self-adaptive control device and method

Abstract

The application provides a power fitting contact resistance adaptive control device and method, and belongs to the technical field of power fitting control, which comprises the following steps: firstly, initializing the device and presetting parameters; then, monitoring module acquires multiple parameters in real time and transmits them to the control module; the control module performs data preprocessing and abnormality judgment, runs an adaptive control algorithm to output instructions; the execution module adjusts to form a closed-loop feedback for continuous regulation and control, and alarms in case of abnormality; meanwhile, the communication module supports remote monitoring and manual intervention, can issue instructions, and the control module suspends the adaptive regulation and control execution operation, and automatically restores after ending. The application adopts the above-mentioned power fitting contact resistance adaptive control device and method, solves the problems of the existing power fitting contact resistance control mode of "passive protection and regular maintenance", such as unadjustable contact pressure, disconnection of detection control, lagging response, weak environmental interference resistance, low control precision and high energy consumption.

Description

Technical Field

[0001] This invention relates to the field of power fitting control technology, and in particular to an adaptive control device and method for the contact resistance of power fittings. Background Technology

[0002] As a "critical node" in power transmission lines, power fittings play a vital role in power grid operation, performing core functions such as conductor connection, fixation, and current diversion. The stability of their contact resistance is crucial, directly determining the conductivity reliability and operational safety of the power grid. Contact resistance is the inherent resistance at the connection point of power fittings (such as the contact surface between a conductor and a clamp), and its value is affected by various factors, including contact pressure, contact surface cleanliness, environmental corrosion, temperature changes, and mechanical vibration.

[0003] In existing technologies, the control of contact resistance in power fittings mainly adopts a "passive protection and periodic maintenance" model. Firstly, the contact pressure is not adjustable, making it difficult to adaptively compensate for poor contact caused by wear and loosening. During installation, the contact pressure is set by pre-tightening the bolts. However, during long-term service, factors such as conductor creep, wind-induced vibration, and thermal cycling can cause bolts to loosen and contact surfaces to wear, leading to a decrease in contact pressure. This decrease in contact pressure significantly increases contact resistance, creating a positive feedback loop of "point heating—oxidation—further increase in resistance," which may ultimately lead to localized high temperatures, carbon buildup, or even serious accidents such as conductor burnout.

[0004] Secondly, detection and control are disconnected, resulting in a significant lag in response. Existing contact resistance detection methods are mostly offline, such as the DC voltage drop method and the micro-ohmmeter method. These methods require shutdown and cannot capture dynamic changes in contact resistance in real time. Furthermore, manual intervention is needed after detection, further contributing to the significant lag in response and making it difficult to effectively handle sudden contact resistance anomalies.

[0005] Furthermore, they have weak resistance to environmental interference. In harsh environments such as high salt spray, high humidity, and heavy pollution, the contact surfaces of power fittings are prone to oxidation and dirt accumulation, leading to excessive fluctuations in contact resistance. However, existing devices lack targeted adaptive control mechanisms and cannot dynamically optimize the contact state according to environmental changes, making it difficult to guarantee the stability of contact resistance.

[0006] Finally, the control accuracy is low and energy consumption is high. Some simple control devices use fixed threshold trigger control, which does not fully consider the coupling relationship between contact resistance and temperature and current, resulting in insufficient control accuracy. At the same time, this control method also has the problem of over-control, resulting in energy waste, and it cannot balance mechanical strength and electrical performance. Summary of the Invention

[0007] The purpose of this invention is to provide an adaptive control device and method for the contact resistance of power fittings, which solves the problems of existing power fitting contact resistance control adopting the "passive protection and periodic maintenance" mode, which has problems such as unadjustable contact pressure, disconnection between detection and control, delayed response, weak resistance to environmental interference, low control accuracy and high energy consumption, thus affecting the reliability of power grid operation.

[0008] To achieve the above objectives, the present invention provides an adaptive control method for the contact resistance of power fittings, comprising the following steps: S1. Device initialization and parameter preset: Install the device on the target power fitting, start the power supply module, and the control module completes initialization. Preset the optimal range of contact resistance, the target range of contact pressure, the environmental parameter threshold and the control algorithm parameters, and set the initial value of the pseudo-partial derivative. S2. Real-time monitoring of multiple parameters: The monitoring module continuously collects contact resistance, contact pressure, contact temperature, ambient humidity and salt spray concentration according to the preset sampling cycle. After processing by the signal conditioning circuit, the data is transmitted to the control module. S3. Data preprocessing and anomaly detection: The control module uses the 3σ criterion to remove abnormal data, corrects the contact resistance using the temperature compensation formula to obtain the temperature-compensated contact resistance, and simultaneously determines whether there are any abnormalities in environmental parameters, contact resistance, and sensors. S4. Adaptive control algorithm operation and control command output: The control module updates the pseudo-partial derivatives based on the preprocessed parameters. If there is an environmental anomaly, the adaptive gain is corrected. The contact pressure increment and the contact pressure target value are calculated. The target value is determined to be within the preset range. The corresponding PWM control command is then output to the execution module. S5. Closed-loop feedback and continuous control: After the execution module responds to the control command and adjusts the contact pressure, the monitoring module continues to collect relevant parameters. The control module repeats S3-S4 until the contact resistance is stable within the preset optimal range. If the contact resistance continues to be abnormal, a fault alarm will be activated. S6. Remote monitoring and manual intervention: The communication module uploads the device's operating parameters in real time. Manual control commands can be issued through the monitoring center. The control module pauses adaptive regulation and performs manual operation. After the operation is completed, the adaptive regulation mode is automatically restored.

[0009] Preferably, the temperature compensation formula is: ; in, R is the temperature-compensated contact resistance, α is the temperature coefficient of resistance of the power fitting material, and T is the measured temperature of the contact area.

[0010] Preferably, the improved model-free adaptive control algorithm includes pseudo-partial derivative estimation and control law calculation. The pseudo-partial derivative estimation formula is as follows: ; The formula for the control law is: ; in, The pseudo-partial derivative at time k, Here, ρ is the pseudo-partial derivative at time k-1, and ρ is the estimated step size. For the contact pressure increment at time k, The contact pressure increment at time k-1 Let K be the contact resistance after temperature compensation at time k. Let α be the contact resistance after temperature compensation at time k-1, α be the filter coefficient, and λ be the adaptive gain. This is the target value for contact resistance.

[0011] Preferably, when environmental parameters are abnormal, the correction formula for the adaptive gain is: ; in, This is the corrected adaptive gain. Temperature threshold Humidity threshold Where is the salt spray concentration threshold, T is the measured temperature, H is the measured humidity, and S is the measured salt spray concentration.

[0012] Preferred target contact pressure value: ; like Within the preset contact pressure target range Inside, the servo motor is adjusted to... ;like Adjust to ;like Adjust to .

[0013] Preferably, the criterion for determining persistently abnormal contact resistance is the contact resistance after temperature compensation over 10 consecutive sampling periods. If the fault exceeds the preset optimal range, the communication module will upload the abnormal parameters, fault location, and fault type to the remote monitoring center when a fault alarm is triggered.

[0014] An adaptive control device for the contact resistance of power fittings includes a monitoring module, a control module, an execution module, a power supply module, and a communication module. The monitoring module, execution module, power supply module, and communication module are all electrically connected to the control module, and the modules work together to realize real-time monitoring and adaptive regulation of the contact resistance of power fittings. The monitoring module is used to collect multi-dimensional parameters of the contact parts of the power fittings and transmit them to the control module. The control module is used to receive monitoring data, run adaptive control algorithms and output control commands. The execution module is used to respond to control commands and adjust the contact pressure of the power fittings. The power supply module is used to provide stable power to each module. The communication module is used to realize data interaction between the control module and the remote monitoring center.

[0015] Preferably, the monitoring module includes a contact resistance detection unit, a contact pressure detection unit, an environmental and temperature detection unit, and a signal conditioning circuit; The contact resistance detection unit adopts a four-terminal measurement method, including a high-precision constant current source and a differential voltage acquisition device, which are used to collect the contact resistance value of the contact parts of power fittings. The contact pressure detection unit uses a strain gauge pressure sensor to collect the contact pressure value of the contact parts of the power fittings; The environmental and temperature detection unit includes a temperature sensor, a humidity sensor, and a salt spray concentration sensor, which are used to collect the temperature of the contact area, the ambient humidity, and the salt spray concentration. The signal conditioning circuit uses a second-order low-pass filter circuit to filter, amplify, and convert analog signals acquired by each sensor to digital.

[0016] Preferably, the control module adopts an embedded microcontroller, which integrates memory, timer and interrupt controller, and is used to preprocess monitoring data, run an improved model-free adaptive control algorithm, judge abnormal parameters and output control commands; The control module can store historical monitoring data, use the 3σ criterion to eliminate abnormal data, and dynamically adjust the control algorithm parameters according to environmental parameters. When the contact resistance continuously exceeds the preset threshold or the sensor fails, it outputs a fault alarm signal.

[0017] Preferably, the execution module includes a drive unit, a servo motor, and a pressure feedback adjustment unit; the drive unit is a DC servo driver with overcurrent, overvoltage, and overheat protection functions, used to receive PWM control signals from the control module and drive the servo motor to run; The servo motor is a small DC servo motor, which is bolted to the power fittings via a reduction gear mechanism; The pressure feedback adjustment unit is linked with the contact pressure detection unit to feed back real-time contact pressure data to the control module, forming a closed-loop control. When the contact pressure reaches the target value, the servo motor is controlled to stop running and the bolt position is locked.

[0018] Therefore, the present invention employs the above-mentioned adaptive control device and method for contact resistance of power fittings, and the technical effects are as follows: 1. It achieves adaptive closed-loop control of contact resistance, solving the pain points of existing technologies such as "passive protection and delayed response": By monitoring contact resistance, contact pressure and environmental parameters in real time, it adopts an improved MFAC algorithm to dynamically adjust the contact pressure, automatically compensate for the increase in contact resistance caused by wear, relaxation and environmental corrosion, stabilize the contact resistance in the optimal range, avoid the positive feedback loop of "point heating - oxidation - resistance increase", and reduce the risk of equipment failure.

[0019] 2. Multi-parameter collaborative monitoring and compensation, high control accuracy and strong anti-interference ability: It integrates multi-dimensional monitoring of contact resistance, pressure, temperature, humidity and salt spray concentration. It eliminates the influence of temperature on contact resistance through temperature compensation formula, and responds to environmental changes through dynamic correction of adaptive gain, adapting to complex outdoor environments.

[0020] 3. No need for frequent manual intervention, reducing maintenance costs: It adopts a complementary power supply of "solar energy + lithium battery", with low standby power consumption, and can achieve long-term outdoor autonomous operation; remote monitoring and fault alarm are realized through LoRa wireless communication, reducing the number of manual inspections and reducing maintenance costs, especially suitable for the control of fittings in remote areas and high-altitude transmission lines. Attached Figure Description

[0021] Figure 1 This is a structural block diagram of an adaptive control device for contact resistance of power fittings according to the present invention. Figure 2 This is a flowchart of an adaptive control method for contact resistance of power fittings according to the present invention; Figure 3 This is a comparison chart of the control effects of the improved MFAC algorithm of this invention and the traditional PI control. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0024] Example 1 like Figure 1 As shown, this invention provides an adaptive control device for the contact resistance of power fittings. It monitors the contact resistance, contact pressure, temperature, and environmental parameters of power fittings in real time, achieving multi-parameter collaborative monitoring and accurately capturing changes in contact state. This device integrates a monitoring module, a control module, an execution module, a power supply module, and a communication module. These modules work collaboratively to achieve real-time monitoring and adaptive adjustment of the contact resistance.

[0025] The monitoring module is used to collect multi-dimensional parameters of the contact parts of power fittings to provide data support for control decisions. It includes a contact resistance detection unit, a contact pressure detection unit, an environmental and temperature detection unit, and a signal conditioning circuit.

[0026] The contact resistance detection unit employs a four-terminal measurement method, consisting of a high-precision constant current source, a differential voltage acquisition unit, and a signal conditioning circuit. During operation, the constant current source outputs a constant DC current to the hardware contact area, ranging from 1-10A, and can adaptively adjust according to the hardware specifications. The differential voltage acquisition unit collects the voltage drop across the contact area and then accurately calculates the contact resistance using Ohm's law.

[0027] The contact pressure detection unit uses a strain gauge-type miniature pressure sensor, which is attached between the hardware contact surface and the pressure block. This sensor has a measurement range of 0-50kN and an accuracy of ≤±0.5%FS. It can acquire contact pressure values ​​in real time, accurately capturing pressure changes caused by bolt loosening, contact surface wear, etc., providing crucial data for subsequent analysis.

[0028] The environmental and temperature detection unit includes multiple sensors to comprehensively collect relevant environmental parameters. Among them, the temperature sensor uses a PT100 with a measurement range of -40℃ to 150℃ and an accuracy of ±0.1℃, accurately measuring the temperature of the hardware contact points; the humidity sensor has a measurement range of 0-100%RH and an accuracy of ±2%RH, used to collect ambient humidity; and the salt spray concentration sensor is specifically designed to collect salt spray concentration. The data collected by these sensors is primarily used to compensate for the effects of temperature and environmental factors on contact resistance.

[0029] The signal conditioning circuit is responsible for processing the analog signals acquired by each sensor. First, it performs filtering and amplification, then performs analog-to-digital conversion to convert the analog signals into digital signals, which are then transmitted to the control module. In the filtering stage, a second-order low-pass filter circuit is used, with a cutoff frequency set to 10Hz, which effectively suppresses electromagnetic interference, ensures signal stability, and achieves a signal-to-noise ratio (SNR) > 60dB.

[0030] The control module is the core of the device. It adopts an embedded microcontroller (MCU) and integrates memory, timer and interrupt controller. It is used to receive digital signals from the monitoring module, run adaptive control algorithm and output control commands to the execution module.

[0031] The control module preprocesses various parameters transmitted from the monitoring module, including contact resistance R, contact pressure F, temperature T, humidity H, and salt spray concentration S. During processing, the 3σ criterion is used to remove outlier data to ensure accuracy and reliability. The control module also has data storage capabilities, storing up to one year of historical data and supporting cyclic overwrite storage for easy subsequent data retrieval and analysis.

[0032] The control module operates an improved model-free adaptive control (MFAC) algorithm, which combines a compact-format dynamic linearization algorithm. Its significant advantage lies in the fact that it eliminates the need for a precise mathematical model, dynamically adjusting the control strategy solely based on input and output data. This effectively adapts to the nonlinear changes in contact resistance, achieving precise control over it. The control module pre-sets an optimal range for contact resistance, which is configured according to different fitting models; for example, the optimal range for parallel groove clamps is set to 0.001-0.01Ω. When the contact resistance exceeds this optimal range, the control module immediately outputs a control command to the execution module to adjust the contact pressure. Furthermore, when temperature, humidity, or salt spray concentration exceeds preset thresholds, the control module activates a compensation mechanism to optimize control parameters, ensuring stable operation under various environmental conditions. During operation, if the contact resistance consistently exceeds the threshold (e.g., exceeding 0.05Ω), or if a sensor malfunctions, the control module promptly outputs an alarm signal and uploads the alarm information to the monitoring center via the communication module, enabling personnel to take timely measures to prevent accidents.

[0033] The execution module is used to respond to the instructions of the control module and adjust the contact pressure of the power fittings, thereby regulating the contact resistance. It includes a drive unit, a servo motor, and a pressure feedback adjustment unit.

[0034] The drive unit employs a DC servo driver, whose core function is to receive PWM control signals from the control module and drive the servo motor accordingly. To ensure operational safety, the DC servo driver is equipped with a comprehensive protection mechanism, including overcurrent, overvoltage, and overheat protection. This allows for timely intervention in abnormal situations to prevent equipment damage and ensure the stable and reliable operation of the entire system. A small DC servo motor is selected as the power source, with a power range of 50-100W and an adjustable speed between 0-1000 r / min. This motor is connected to the hardware bolt via a reduction mechanism (reduction ratio set to 1:50). This method converts the high-speed rotation of the motor into the low-speed, precise forward and reverse rotation of the bolt, thereby regulating the contact pressure. The motor exhibits excellent positioning accuracy, ≤±0.1mm. This characteristic provides strong assurance for the precision of pressure regulation, ensuring that the contact pressure can be accurately adjusted to the required value. The pressure feedback regulation unit constructs a closed-loop control system, feeding back real-time pressure data collected by the contact pressure detection unit to the control module. The control module compares and analyzes feedback data with preset target values, and then precisely adjusts control commands to avoid over- or under-regulation of pressure. When the contact pressure reaches the preset target value, the control module issues a command to stop the motor and lock its position, effectively preventing bolts from loosening and ensuring that the contact pressure remains stable within a suitable range, thus guaranteeing stable control of the contact resistance of the power fittings.

[0035] In outdoor scenarios without grid power supply, the power supply module innovatively adopts a complementary power supply mode of solar energy and lithium batteries to ensure the stable operation of the device.

[0036] Solar panels, a key component of this power supply mode, have a power range of 5-10W. They efficiently convert solar energy into electrical energy and then deliver this converted energy to the lithium battery to charge it, providing the initial energy source for the entire power supply system. The lithium battery used is a lithium iron phosphate battery with a capacity of 12V / 5Ah. This type of battery has many advantages, with a cycle life of ≥2000 cycles, significantly reducing the frequency and cost of battery replacement. It also features comprehensive overcharge and over-discharge protection functions, effectively preventing damage to the battery caused by improper charging or discharging and extending battery life. In the absence of sunlight, the lithium battery, with its stored energy, can continuously power the device for ≥72 hours, ensuring normal operation even at night or on cloudy days with insufficient sunlight.

[0037] The power management chip used is the TP4056, which plays a crucial role in stabilizing the output voltage in the power supply module. This chip can stably output both 5V and 12V, providing appropriate power support for the various modules of the device. Furthermore, it effectively reduces energy consumption, keeping the device's standby power consumption ≤100mW, further improving energy efficiency and extending the overall battery life of the device.

[0038] To meet the monitoring needs of power transmission lines and achieve efficient data interaction and stable operation, the communication module of this device adopts LoRa wireless communication technology, with a communication distance of 1-3km, which can well support data interaction with the power transmission line monitoring center.

[0039] During data interaction, the communication module plays a crucial role in bidirectional transmission. For data uploading, it is responsible for uploading key data such as contact resistance, contact pressure, temperature, humidity, salt spray concentration, and device operating status (including both normal and fault conditions) to the monitoring center in real time and accurately, enabling staff to promptly grasp the operational status of the power fittings. For command reception, the communication module can receive manual control commands issued by the monitoring center, such as manually adjusting contact pressure and modifying preset thresholds, thereby achieving remote and precise control and improving operational efficiency. Furthermore, to ensure the reliability and security of data transmission, the communication module adopts the Modbus-RTU protocol. This protocol has strong anti-electromagnetic interference capabilities and can well adapt to the complex electromagnetic environment of high-voltage transmission lines, ensuring stable data transmission.

[0040] In terms of mechanical structure adaptability, this device fully considers the needs of use in harsh outdoor environments. The entire device adopts a waterproof, dustproof, and corrosion-resistant structure with a protection rating of IP65, effectively resisting the erosion of external moisture, dust, and corrosive substances. The outer shell is made of high-strength aluminum alloy, a material with high tensile strength and strong corrosion resistance, capable of adapting to harsh environments such as high salt spray in coastal areas and heavy industrial pollution, ensuring long-term stable operation of the device. At the same time, the device is designed to be compact and lightweight, allowing it to be directly installed on the bolt positions of various electrical fittings (such as parallel groove clamps, splicing fittings, equipment clamps, etc.) without requiring significant modifications to the fittings. The installation process is convenient and efficient, and does not affect the mechanical and electrical properties of the fittings, ensuring the normal operation of the power system.

[0041] like Figures 2-3 As shown, this method, based on the aforementioned device, achieves adaptive control of contact resistance through a closed-loop process of "monitoring-analysis-control-feedback". The core lies in using an improved model-free adaptive control (MFAC) algorithm to dynamically match the nonlinear relationship between contact resistance and contact pressure, achieving high-precision control without the need to establish an accurate mathematical model.

[0042] The relationship between the contact resistance R and the contact pressure F of power fittings is significantly nonlinear and is affected by factors such as temperature T, ambient humidity H, and salt spray concentration S. Its nonlinear characteristics can be described as follows: ; Here, f(·) is an unknown nonlinear function, and an accurate mathematical model cannot be established through theoretical derivation. Traditional linear control algorithms struggle to adapt to its dynamic changes, resulting in insufficient control accuracy and anti-interference capabilities. To address these issues, this invention employs a model-free adaptive control (MFAC) algorithm. This algorithm does not rely on an accurate model but dynamically approximates the system characteristics using only real-time data from the system input (contact pressure F) and output (contact resistance R), thus achieving adaptive control.

[0043] Secondary interferences are eliminated first, focusing on the core coupling relationship between contact resistance R and contact pressure F. Simultaneously, temperature compensation is introduced to eliminate the main interference from temperature T, resulting in the temperature-compensated contact resistance. At this point, the core relationship can be simplified to: ; At this point, the system is a nonlinear single-input single-output system. A compact scheme dynamic linearization method is used to transform the nonlinear system... The system is approximated as a discrete-time linear system near the current operating point to reduce control complexity while preserving its dynamic characteristics. An adaptive estimation formula for pseudo-partial derivatives (reflecting the influence of contact pressure changes on contact resistance) is designed, and these pseudo-partial derivatives are updated in real-time using historical input-output data to adapt to nonlinear changes in the system. Based on the linearized model and the estimated pseudo-partial derivatives, a control law for the contact pressure increment is designed to ensure rapid convergence of the contact resistance to the preset optimal range. Upper and lower pressure limits are also incorporated to avoid over-regulation. A compensation mechanism for environmental parameters (H, S) is introduced to dynamically correct the control parameters, improving the algorithm's anti-interference capability and adapting to complex outdoor environments.

[0044] The contact resistance increases with increasing temperature, following a linear temperature characteristic law. Its original measured value R is significantly affected by temperature, requiring temperature compensation to ensure control accuracy. The derivation is based on the temperature characteristic formula for metal resistors: ; in, The resistance value (Ω) is at temperature T. The resistance value (Ω) is the standard reference temperature of 25℃, α is the temperature coefficient of resistance of the fitting material (copper α=0.00393 / ℃, aluminum α=0.00429 / ℃), and T is the measured temperature (℃).

[0045] In this invention, the measured value R of the contact resistance is... The goal of temperature compensation is to correct the measured value to the equivalent resistance at a standard temperature of 25°C. (Right now Therefore, by transforming the above formula, we obtain the temperature compensation formula: ; When the measured temperature T>25℃ , The correction eliminates the artificially high resistance caused by temperature rise; when T < 25℃, , The correction eliminates the falsely low resistance caused by temperature drop, ensuring the accuracy of the contact resistance detection value.

[0046] For nonlinear systems after temperature compensation (k is the sampling time). Assuming that the system satisfies the "generalized Lipschitz condition" (i.e., there is a bounded relationship between the input and output changes), the compact scheme dynamic linearization method is used to approximate it as a discrete-time linear system.

[0047] Define the increment of contact resistance as The increase in contact pressure is Then the nonlinear system can be approximated as: ; in, It is the pseudo-partial derivative at time k-1, and its physical meaning is "the change in contact resistance for every 1kN change in contact pressure at time k-1". It reflects the sensitivity of the influence of contact pressure on contact resistance, and its value changes dynamically with the working state of the system (negative value, because the contact resistance decreases when the contact pressure increases).

[0048] From the above incremental transformation, we obtain the prediction formula for the contact resistance at time k: ; Extending further to time k+1, we obtain the linearized model used for control decisions: ; This linearized model allows us to determine the contact resistance at the current time (time k). pseudo-partial derivatives and contact pressure increment Predict the contact resistance at time k+1. This provides a foundation for the design of control laws.

[0049] pseudo-partial derivatives This cannot be obtained through theoretical calculations and requires adaptive estimation using historical input and output data. The estimation criterion is to "minimize the error between the predicted and measured values ​​of the contact resistance at time k," i.e., to minimize the cost function. ; in, The predicted value of the contact resistance at time k (obtained from the linearized model at time k-1, i.e.) α is the filtering coefficient, used to suppress the influence of measurement noise on the estimated value and avoid excessive fluctuations in the pseudo-partial derivative.

[0050] For cost function about Find the partial derivatives and set them to 0 (extremum condition). After simplification, we obtain the adaptive estimation formula for the pseudo-partial derivatives: ; in, To estimate the step size, the update speed of the pseudo-partial derivative is adjusted. The larger the ρ is, the faster the update, but the weaker the anti-interference ability; the smaller the ρ is, the smoother the update and the stronger the anti-interference ability. In combination with the power fitting control requirements, the optimized value is 0.01. α is the filtering coefficient, used to smooth the pseudo-partial derivative estimate and reduce the influence of measurement noise. The closer α is to 1, the better the filtering effect, which is suitable for the low noise requirements of contact resistance detection. The prediction error of the contact resistance reflects the estimation deviation of the pseudo-partial derivative at the previous moment. This error is used to correct the pseudo-partial derivative at the current moment, thereby achieving adaptive updating. Used to avoid a denominator of 0 (when the contact pressure does not change). (The denominator is α, to ensure the formula is meaningful), while suppressing estimation fluctuations when the contact pressure changes significantly.

[0051] The control objective is to minimize the contact resistance at time k+1. Converging to the preset target value (Optimal range median) ), combined with the linearized model, let Substituting into the formula, we get: ; By transforming the above formula, we obtain the contact pressure increment. Basic control law: ; To improve control stability and convergence speed, an adaptive gain is introduced. (Preset λ=0.8), used to adjust the magnitude of the pressure increment to avoid over- or under-regulation, ultimately yielding the optimized control law formula: ; when When the contact resistance is too high, the molecules And pseudo-partial derivatives ,therefore Increased contact pressure reduces contact resistance. when When the contact resistance is low, the molecules , ,therefore This reduces contact pressure and prevents excessive tightening that could damage the hardware. Adaptive gain The range of values ​​is 0 < <1. The closer λ is to 1, the larger the control amplitude and the faster the convergence speed; the closer λ is to 0, the smaller the control amplitude and the stronger the stability. Based on simulation optimization, λ=0.8 is determined to be the optimal value.

[0052] When the ambient humidity H and salt spray concentration S exceed the preset thresholds, the contact surfaces of the fittings are prone to oxidation and contamination, leading to increased fluctuations in contact resistance. This necessitates adjustments to the adaptive gain. Enhance control sensitivity and compensate for environmental interference. The more severe the environmental interference, the higher the control sensitivity. The compensation formula is: ; in, This is the corrected adaptive gain. , , These are the normalized values ​​for temperature, humidity, and salt spray concentration, respectively.

[0053] The specific method based on the above closed-loop regulation is as follows: S1. Device initialization and parameter preset; Install the device onto the bolted part of the target power fitting (such as a parallel cable clamp), connect the circuits of each module, and start the power supply module; initialize the control module and preset the following parameters: Optimal range of contact resistance According to the model of the hardware, such as parallel groove clamp. , ; Contact pressure target range Based on the material and specifications of the fittings, the pressure for copper-copper contact is ≥10MPa, and for aluminum-aluminum contact it is ≥15MPa. The corresponding pressure values ​​are determined by the relationship between bolt torque and contact pressure. Calculate, where T is the torque, K is a coefficient of 0.2, and d is the bolt diameter; Set environmental parameter thresholds, temperature ,humidity Salt spray concentration ; Set control algorithm parameters, sampling period Adaptive gain Pseudo-partial derivative estimation step size Filter coefficients ; Set initial values ​​for pseudopartial derivatives It is preset based on the material characteristics of the hardware and subsequently updated through an adaptive algorithm.

[0054] S2. Real-time monitoring of multiple parameters: The monitoring module operates according to the sampling period. It continuously collects contact resistance R, contact pressure F, and environmental and temperature parameters. The collected analog signals are processed by a signal conditioning circuit (second-order low-pass filtering, amplification, and 16-bit ADC conversion) and then converted into digital signals, which are then transmitted to the control module.

[0055] Data is collected via a contact resistance detection unit using a four-terminal measurement method. The calculation formula is as follows: ; Where U is the voltage drop across the contact point (V), and I is the constant current source output current (A); the constant current source output current I is adaptively adjusted according to the hardware specifications (1-10A) to ensure measurement accuracy; The pressure sensor collects and directly obtains the real-time pressure value (kN), which is then transmitted to the signal conditioning circuit for filtering. The following parameters were collected: temperature T (°C) at the contact point, ambient humidity H (%RH), and salt spray concentration S (mg / m³). 3 The temperature sensor uses a PT100 to ensure measurement accuracy in low-temperature environments.

[0056] S3. Data Preprocessing and Anomaly Detection: The control module first uses the 3σ criterion to eliminate abnormal data from the received digital signal and replaces it with the valid data from the previous moment. Then, it performs temperature compensation. Subsequently, it judges abnormalities from three aspects: environment, contact resistance, and sensor, and initiates the corresponding compensation, regulation, or alarm process respectively. Outlier data is removed using the 3σ criterion: if the measured value of a parameter deviates from the average value by more than three times the standard deviation, it is considered outlier data and is replaced by valid data from the previous time step. Calculate the contact resistance after temperature compensation using the temperature compensation formula. To eliminate the influence of temperature on contact resistance; for example, when the measured temperature T=85℃, for copper fittings (α=0.00393 / ℃), the measured contact resistance R=0.012Ω, ; like , or If the environment is marked as abnormal, the environmental compensation mechanism will be activated. like If the contact resistance is abnormal, the process will proceed. If a sensor has no data output or the data is continuously abnormal (exceeding the measurement range for 3 consecutive sampling cycles), it is marked as a sensor fault, and the alarm process is initiated.

[0057] S4. Adaptive control algorithm operation and control command output: Based on the preprocessed parameters, the control module first updates the pseudo-partial derivatives. If there are environmental anomalies, it corrects the adaptive gain. Then, it calculates the contact pressure increment and determines whether the pressure target value is within the preset range. Based on this, it outputs different control commands to the execution module to regulate the contact pressure.

[0058] Update the pseudopartial derivatives at the current time step according to the adaptive estimation formula of the pseudopartial derivatives. ; When k=1 , ,but: When k=2, if , ,but: ; If environmental anomalies exist, the adaptive gain should be adjusted according to the environmental parameter compensation formula. ; When T=100℃, H=80%RH, S=0.12mg / m³ 3 Then: ; Calculate the contact pressure increment at the current moment using the control law formula. ; when , , , Then: ; Calculate the target value of contact pressure Determine whether it is within the preset range. Within the range: like The PWM control signal is output to the execution module to control the servo motor (forward rotation to tighten the bolt, reverse rotation to loosen the bolt), so that the contact pressure reaches... ; like The output control signal causes the motor to reverse, adjusting the contact pressure to... ; like The output control signal causes the motor to rotate forward, adjusting the contact pressure to... To avoid over-adjustment that could damage the hardware.

[0059] S5, Closed-loop feedback and continuous regulation: After the execution module adjusts the contact pressure, the monitoring module continuously collects parameters and transmits them to the control module to form a closed-loop feedback. The control module calculates and judges whether to stop the motor and enter the next cycle for continuous regulation, or to rerun the algorithm and output new instructions until the contact resistance stabilizes. If the contact resistance continues to exceed the threshold, a fault alarm is activated and information is uploaded.

[0060] After the execution module adjusts the contact pressure, the monitoring module continues to collect contact resistance data according to the sampling cycle. Contact pressure These parameters are transmitted to the control module to form a closed-loop feedback.

[0061] The control module repeats steps S3-S4 to calculate the contact resistance after temperature compensation. ,judge Has it fallen into ; like The motor is stopped, the bolt position is locked, and the next sampling cycle begins. S2-S5 is repeated to achieve continuous monitoring and control. like Still not fallen The control module re-runs the adaptive control algorithm and updates the pseudo-partial derivatives. and contact pressure increment Output new control commands until the contact resistance stabilizes within the optimal range; If the contact resistance continuously exceeds the threshold (e.g., for 10 consecutive sampling cycles) The control module activates a fault alarm and uploads the alarm information (including abnormal parameters and fault location) to the monitoring center via the communication module, reminding staff to troubleshoot the fault (such as contact surface oxidation, sensor failure, etc.).

[0062] S6. Remote monitoring and manual intervention: The communication module uploads the device's operating parameters (contact resistance, contact pressure, environmental parameters, and operating status) to the monitoring center in real time. Staff can view the device's operating status through the monitoring center. When manual intervention is required (such as maintenance or parameter adjustment), a manual control command is issued. After receiving the command, the control module pauses adaptive control and executes manual control operations (such as manually adjusting contact pressure or modifying preset parameters). After the manual intervention ends, the device automatically resumes adaptive control mode.

[0063] Specifically, the above device is applied to the parallel trench clamp (model JBB-120) of a 110kV transmission line. The specific implementation steps are as follows: The adaptive control device is fixed to the bolt part of the parallel groove clamp, the pressure sensor is attached between the contact surface of the clamp and the pressure block, the two test ends of the contact resistance detection unit are respectively connected to the two contact terminals of the clamp, and the solar panel is fixed on the pole near the clamp to ensure sufficient lighting.

[0064] Optimal range of contact resistance Contact pressure target range (Corresponding aluminum-aluminum contact pressure ≥15MPa), temperature threshold Humidity threshold Salt spray concentration threshold Control algorithm parameters: sampling period , , , initial values ​​of pseudo-partial derivatives .

[0065] After the device is started, the monitoring module collects contact resistance, contact pressure, temperature, humidity, and salt spray concentration every 0.5 seconds; when the contact resistance R=0.012Ω (temperature T=35℃, copper material α=0.00393 / ℃, after temperature compensation: (Exceeding the optimal range), contact pressure F=14kN (below the target range); the control module runs an adaptive control algorithm to update the pseudo-partial derivatives. Calculate the contact pressure increment Target value of contact pressure (Falling into the target range); the control module outputs a PWM signal to drive the servo motor to rotate forward, and the adjusting bolt is tightened to make the contact pressure reach 18kN. At this time, the contact resistance... It stabilizes within the optimal range.

[0066] In a coastal high-salt fog environment (S=0.12mg / m³), 3 Under these conditions, the device automatically corrects the adaptive gain. Enhanced control sensitivity, contact resistance fluctuation amplitude ≤4%, stable within the optimal range; Artificial oxidation of the contact surface leads to increased contact resistance. If the device detects an anomaly after 10 consecutive sampling cycles (exceeding the threshold), it will activate a fault alarm and upload the alarm information to the monitoring center via LoRa communication. Staff will promptly investigate the fault, clean the oxide layer on the contact surface, and the device will resume normal operation.

[0067] Specifically, the device is applied to the equipment clamps (model DTL-240) of a 220kV transmission line. The specific implementation steps are as follows: The device is installed on the bolt part of the equipment clamp. The contact resistance detection unit adopts the four-terminal measurement method. The test end is connected to the contact part between the equipment clamp and the busbar. The temperature sensor is in close contact with the contact surface to ensure accurate measurement.

[0068] Optimal range of contact resistance Contact pressure target range (Copper-copper contact pressure ≥10MPa), other parameters are consistent with those of the parallel trench clamps used in 110kV transmission lines.

[0069] When the circuit is overloaded, the temperature of the contact points rises to 100℃, and the contact resistance R = 0.009Ω. After temperature compensation... (Falls within the optimal range, no adjustment required); When the temperature continues to rise to 110℃, the contact resistance R = 0.010Ω, after temperature compensation. (Still within the optimal range); When the temperature rises to 125℃ (exceeding the temperature threshold), the contact resistance R = 0.012Ω, after temperature compensation. Although still within the optimal range, the device activates the environmental compensation mechanism, adjusting the adaptive gain according to the temperature parameter compensation formula. To enhance the sensitivity of regulation and continuously monitor the contact status.

[0070] When the line overload intensifies, the contact resistance R rises to 0.015Ω, and the temperature T=130℃. After temperature compensation... The resistance level exceeds the upper limit of the optimal range by 0.008Ω, and the contact pressure F = 19kN (below the lower limit of the target range by 20kN). The control module runs an adaptive control algorithm to update the pseudo-partial derivatives. Combined with the corrected adaptive gain The contact pressure increment is calculated based on the optimized control law formula. Target value of contact pressure (Falling within the 20-30kN target range); the control module outputs a PWM signal to drive the servo motor to rotate forward and tighten the bolts, so that the contact pressure reaches 23.07kN, at which point the temperature-compensated contact resistance... It stabilizes within the optimal range, effectively preventing abnormal increases in contact resistance caused by overload.

[0071] In heavily polluted industrial environments with high humidity (H=90%RH, S=0.09mg / m³), 3 At T=45℃, the contact surface of the equipment clamps is prone to dirt accumulation, causing slight fluctuations in contact resistance. The device monitors environmental parameters and determines that the humidity exceeds the threshold (85%RH), then activates the environmental compensation mechanism to correct the adaptive gain. Through closed-loop control, the contact resistance fluctuation range is ≤3.5%, and it remains stable within the optimal range of 0.0008-0.008Ω, verifying the adaptability of the device in harsh industrial environments.

[0072] A simulated pressure sensor failure (no data output) was initiated. The device failed to receive pressure data for three consecutive sampling cycles, which was determined to be a sensor failure. The fault alarm was immediately activated, and the fault information (fault type: pressure sensor failure, fault location: 220kV equipment clamp control device) was uploaded to the monitoring center via LoRa communication. The staff took a spare sensor to the site for replacement. After replacement, the device automatically restarted, completed initialization, and restored the adaptive control mode. Within 10 sampling cycles after restarting, the contact resistance stabilized at around 0.0045Ω, and the control returned to normal.

[0073] The device operated continuously on a 220kV equipment clamp for 6 months, enduring complex conditions such as high temperature, heavy rain, and industrial dust. It was adjusted a total of 127 times, with an average steady-state error of contact resistance ≤ ±0.0004Ω and an average response time of 0.28s. No equipment failures occurred. Compared with traditional equipment clamps without adjustment devices, the contact resistance fluctuation was reduced by 82%, effectively avoiding the risk of overheating caused by abnormal contact resistance, and verifying the long-term stability and practicality of the device.

[0074] Therefore, the present invention adopts the above-mentioned adaptive control device and method for contact resistance of power fittings. The device integrates monitoring, control, execution, power supply and communication modules, and can collect multi-dimensional parameters such as contact resistance, contact pressure, temperature, humidity and salt spray concentration in real time. The control method is based on the improved model-free adaptive control (MFAC) algorithm. Through temperature compensation, tight-form dynamic linearization, pseudo-partial derivative adaptive estimation and environmental parameter compensation, it realizes closed-loop adaptive regulation of contact resistance, stabilizes the contact resistance within the preset optimal range, adapts to complex outdoor environments, and does not require frequent manual intervention.

[0075] 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 them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for adaptive control of contact resistance in power fittings, characterized in that, Includes the following steps: S1. Device initialization and parameter preset: Install the device on the target power fitting, start the power supply module, and the control module completes initialization. Preset the optimal range of contact resistance, the target range of contact pressure, the environmental parameter threshold and the control algorithm parameters, and set the initial value of the pseudo-partial derivative. S2. Real-time monitoring of multiple parameters: The monitoring module continuously collects contact resistance, contact pressure, contact temperature, ambient humidity and salt spray concentration according to the preset sampling cycle. After processing by the signal conditioning circuit, the data is transmitted to the control module. S3. Data preprocessing and anomaly detection: The control module uses the 3σ criterion to remove abnormal data, corrects the contact resistance using the temperature compensation formula to obtain the temperature-compensated contact resistance, and simultaneously determines whether there are any abnormalities in environmental parameters, contact resistance, and sensors. S4. Adaptive control algorithm operation and control command output: The control module updates the pseudo-partial derivatives based on the preprocessed parameters. If there is an environmental anomaly, the adaptive gain is corrected. The contact pressure increment and the contact pressure target value are calculated. The target value is determined to be within the preset range. The corresponding PWM control command is then output to the execution module. S5. Closed-loop feedback and continuous control: After the execution module responds to the control command and adjusts the contact pressure, the monitoring module continues to collect relevant parameters. The control module repeats S3-S4 until the contact resistance is stable within the preset optimal range. If the contact resistance continues to be abnormal, a fault alarm will be activated. S6. Remote monitoring and manual intervention: The communication module uploads the device's operating parameters in real time. Manual control commands can be issued through the monitoring center. The control module pauses adaptive regulation and performs manual operation. After the operation is completed, the adaptive regulation mode is automatically restored.

2. The adaptive control method for contact resistance of power fittings according to claim 1, characterized in that, The temperature compensation formula is: ； in, R is the temperature-compensated contact resistance, α is the temperature coefficient of resistance of the power fitting material, and T is the measured temperature of the contact area.

3. The adaptive control method for contact resistance of power fittings according to claim 1, characterized in that, The improved model-free adaptive control algorithm includes pseudo-partial derivative estimation and control law calculation. The pseudo-partial derivative estimation formula is as follows: ； The formula for the control law is: ； in, The pseudo-partial derivative at time k, Here, ρ is the pseudo-partial derivative at time k-1, and ρ is the estimated step size. For the contact pressure increment at time k, The contact pressure increment at time k-1 Let K be the contact resistance after temperature compensation at time k. Let α be the contact resistance after temperature compensation at time k-1, α be the filter coefficient, and λ be the adaptive gain. This is the target value for contact resistance.

4. The adaptive control method for contact resistance of power fittings according to claim 1, characterized in that, When environmental parameters are abnormal, the correction formula for adaptive gain is: ； in, This is the corrected adaptive gain. Temperature threshold Humidity threshold Where is the salt spray concentration threshold, T is the measured temperature, H is the measured humidity, and S is the measured salt spray concentration.

5. The adaptive control method for contact resistance of power fittings according to claim 1, characterized in that, Target contact pressure value: ； like Within the preset contact pressure target range Inside, the servo motor is adjusted to... ;like Adjust to ;like Adjust to .

6. The adaptive control method for contact resistance of power fittings according to claim 1, characterized in that, The criterion for determining persistently abnormal contact resistance is the contact resistance after temperature compensation over 10 consecutive sampling periods. If the fault exceeds the preset optimal range, the communication module will upload the abnormal parameters, fault location, and fault type to the remote monitoring center when a fault alarm is triggered.

7. An adaptive control device for contact resistance of power fittings, based on the adaptive control method for contact resistance of power fittings according to any one of claims 1-6, characterized in that, It includes a monitoring module, a control module, an execution module, a power supply module, and a communication module; the monitoring module, execution module, power supply module, and communication module are all electrically connected to the control module, and the modules work together to realize real-time monitoring and adaptive control of the contact resistance of power fittings; The monitoring module is used to collect multi-dimensional parameters of the contact parts of the power fittings and transmit them to the control module. The control module is used to receive monitoring data, run adaptive control algorithms and output control commands. The execution module is used to respond to control commands and adjust the contact pressure of the power fittings. The power supply module is used to provide stable power to each module. The communication module is used to realize data interaction between the control module and the remote monitoring center.

8. The adaptive control device for contact resistance of power fittings according to claim 7, characterized in that, The monitoring module includes a contact resistance detection unit, a contact pressure detection unit, an environmental and temperature detection unit, and a signal conditioning circuit. The contact resistance detection unit adopts a four-terminal measurement method, including a high-precision constant current source and a differential voltage acquisition device, which are used to collect the contact resistance value of the contact parts of power fittings. The contact pressure detection unit uses a strain gauge pressure sensor to collect the contact pressure value of the contact parts of the power fittings; The environmental and temperature detection unit includes a temperature sensor, a humidity sensor, and a salt spray concentration sensor, which are used to collect the temperature of the contact area, the ambient humidity, and the salt spray concentration. The signal conditioning circuit uses a second-order low-pass filter circuit to filter, amplify, and convert analog signals acquired by each sensor to digital.

9. The adaptive control device for contact resistance of power fittings according to claim 7, characterized in that, The control module uses an embedded microcontroller that integrates memory, timers, and interrupt controllers. It is used to preprocess monitoring data, run an improved model-free adaptive control algorithm, detect abnormal parameters, and output control commands. The control module can store historical monitoring data, use the 3σ criterion to eliminate abnormal data, and dynamically adjust the control algorithm parameters according to environmental parameters. When the contact resistance continuously exceeds the preset threshold or the sensor fails, it outputs a fault alarm signal.

10. The adaptive control device for contact resistance of power fittings according to claim 7, characterized in that, The execution module includes a drive unit, a servo motor, and a pressure feedback adjustment unit; the drive unit is a DC servo driver with overcurrent, overvoltage, and overheat protection functions, used to receive PWM control signals from the control module and drive the servo motor to run; The servo motor is a small DC servo motor, which is bolted to the power fittings via a reduction gear mechanism; The pressure feedback adjustment unit is linked with the contact pressure detection unit to feed back real-time contact pressure data to the control module, forming a closed-loop control. When the contact pressure reaches the target value, the servo motor is controlled to stop running and the bolt position is locked.

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