A residual voltage detection circuit based on intelligent feeder terminal

Abstract

The present invention discloses a residual voltage detection circuit based on an intelligent feeder terminal, which relates to the technical field of electric power automation monitoring and control, and solves the problems that the existing residual voltage detection circuit cannot accurately detect the residual voltage signal under special circumstances such as no backup power supply or failure of the backup power supply, as well as the problem that the action voltage range is limited and the adaptive ability to the input voltage is poor; the present invention realizes the function of continuing to work and accurately capturing the residual voltage signal in the absence of a backup power supply through a residual voltage step-down power supply module, a residual voltage signal interlocking holding module, a residual voltage signal isolation output module, a residual voltage signal reset module and a voltage threshold calibration module, while shortening the action time of the detection circuit and optimizing the action voltage range, thereby enhancing the adaptive ability of the detection circuit to the input voltage change; the present invention greatly improves the accuracy and stability of residual voltage detection.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power automation monitoring and control, and more specifically to a residual voltage detection circuit based on an intelligent feeder terminal. Background Art

[0002] With the continuous development of economy, the requirements for the safety and reliability of power grid are getting higher and higher. At present, voltage time feeder automation logic is widely used in the field of domestic distribution automation. This logic can automatically isolate 10kV line faults and restore power supply to the faulty section without relying on communication and distribution master stations, thereby improving the stability of power supply of the power grid and shortening the power outage time of the line.

[0003] The residual voltage detection technology assists the intelligent feeder terminal in identifying the residual voltage signal generated by the reclosing and protection tripping actions during the restoration of power supply to the faulty line when the line loses power. It cooperates with the feeder automation logic to realize the residual voltage locking function, which is a protective measure to prevent the intelligent feeder terminal equipment from mistakenly reclosing and supplying power to the faulty line section after power-on, thereby preventing the occurrence of secondary accidents. For example, patent CN116359674B proposes a method for fault location using voltage transient quantities, which not only improves the accuracy of fault judgment, but also can adapt to different types of fault conditions.

[0004] Although the existing technology has made certain progress, there are still some urgent problems to be solved in practical applications. First, since the residual voltage signal is only generated in special circumstances such as line fault, power failure and power restoration, and disappears quickly due to fault protection and other reasons, the intelligent feeder terminal is required to capture and record the residual voltage signal on the line in a timely and accurate manner. The residual voltage identification function of the traditional feeder terminal mostly needs to be detected normally when the equipment is energized. Therefore, in special circumstances such as no backup power supply or backup power failure, the traditional feeder terminal may not be able to accurately detect the residual voltage signal and participate in the residual voltage locking logic of the terminal. Secondly, the action time of the residual voltage detection circuit is usually required to be less than 40 milliseconds (ms), and the minimum action voltage is 30% U (U is usually 100V or 220V). In practical applications, if the response time of the detection circuit exceeds this limit, or the action voltage is not within the specified range, it may lead to the inability to detect the residual voltage in a timely and accurate manner, thereby affecting the accuracy of the reclosing and the stability of the power system; Finally, some traditional residual voltage detection circuits use transformers for voltage conversion and power output. This design has poor adaptability to the input voltage. When the input voltage changes, the output voltage may be affected, thus affecting the accuracy and stability of the detection circuit. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention discloses a residual voltage detection circuit based on an intelligent feeder terminal to solve the problems raised in the background technology.

[0006] The present invention adopts the following technical solutions:

[0007] A residual voltage detection circuit based on an intelligent feeder terminal, the residual voltage detection circuit comprising a residual voltage step-down power supply module, a residual voltage signal interlocking holding module, a residual voltage signal isolation output module, a residual voltage signal reset module and a voltage threshold calibration module;

[0008] The residual voltage step-down power supply module is used to generate a 5V power supply by using the normal power supply voltage of the line or the residual voltage generated when the line fails, and obtain the corresponding residual voltage signal and output it to the residual voltage signal interlocking holding module;

[0009] The residual pressure signal interlock holding module is used to hold the residual pressure signal detected on the incoming line side or the outgoing line side that exceeds the threshold range and output the dry contact information to the residual pressure signal isolation output module;

[0010] The residual voltage signal isolation output module is used to output the output result of the residual voltage signal interlocking holding module to the system processor through optical coupling isolation;

[0011] The residual pressure signal reset module is used to issue a residual pressure signal reset instruction immediately after the system processor processes the residual pressure locking logic or after the device power is lost, so as to start the residual pressure detection work of the next cycle;

[0012] The voltage threshold calibration module is used to dynamically adjust the output voltage of the residual voltage step-down power supply module using a digital potentiometer according to the real-time input voltage and residual voltage signal characteristics through an adaptive threshold adjustment algorithm, and at the same time feedback adjust the residual voltage detection threshold.

[0013] As a further technical solution of the present invention, the residual voltage step-down power supply module adopts two wide-range isolated ACDC power supply modules at the incoming and outgoing ends of the line respectively; when the line voltage of the residual voltage step-down power supply module fluctuates, the two wide-range isolated ACDC power supply modules monitor the changes of the input voltage in real time through the wide-range input voltage detection and adjustment mechanism, and adjust the power conversion strategy to meet the line voltage greater than 30% Un, and stably output 5V power within a time range of 2 cycles, so as to supply power to the residual voltage signal interlocking holding module.

[0014] As a further technical solution of the present invention, the residual voltage step-down power-taking module monitors the line residual voltage in real time through a voltage divider network and a fast comparator when extracting electric energy. If the residual voltage signal is detected to exceed a preset threshold, a signal capture mechanism is triggered to amplify, shape and filter the residual voltage signal to eliminate noise interference.

[0015] As a further technical solution of the present invention, the working method of the residual voltage signal interlock holding module is as follows: when the residual voltage step-down power supply module successfully extracts a 5V residual voltage power supply signal at the incoming line or the outgoing line, and simultaneously detects a residual voltage signal that exceeds a preset threshold range, a priority action decision is made according to the order of the residual voltage signal source through a timestamp recording and comparison method; if the incoming line side first generates a 5V residual voltage power supply signal accompanied by a residual voltage signal that exceeds the threshold, the first group of switching contacts of the magnetic latching relay is activated, the residual voltage signal on the incoming line is maintained and output to the residual voltage signal isolation output module, and when the incoming line side switching contacts of the magnetic latching relay are activated, the second group of switching contacts of the magnetic latching relay is disconnected through an internal interlocking mechanism, and the residual voltage signal output on the outgoing line is locked; if the outgoing line side first generates a 5V residual voltage power supply signal accompanied by a residual voltage signal that exceeds the threshold, the second group of switching contacts of the magnetic latching relay is activated, the residual voltage signal on the outgoing line is maintained and output to the residual voltage signal isolation output module, and the first group of switching contacts of the magnetic latching relay is disconnected at the same time, and the incoming line signal output is locked.

[0016] As a further technical solution of the present invention, the residual pressure signal isolation output module is based on the dry contact information output by the residual pressure signal interlock holding module, and first identifies and receives the dry contact information through an optocoupler isolation circuit. If there are abnormal residual pressure signals in some contact information, the optocoupler isolation circuit uses an isolation mechanism and a photocoupler to convert the electrical signal at the input end into an optical signal, and then restores the optical signal to an electrical signal through a phototransistor and outputs it to the system processor.

[0017] As a further technical solution of the present invention, the residual pressure signal reset module evaluates the input voltage level in real time through the voltage monitoring unit. If the working voltage change value within the preset time window is lower than the preset threshold, the residual pressure signal is continuously output to the residual pressure signal isolation output module through the steady-state maintenance mechanism; if the working voltage change value within the preset time window is equal to or higher than the preset threshold, a reset pulse is sent to the residual pressure signal interlock holding module to reset the residual pressure signal interlock holding module, disconnect the current residual pressure signal output path, and start the residual pressure detection work of the next cycle.

[0018] As a further technical solution of the present invention, the working method of the voltage threshold calibration module is: first, the input voltage and residual voltage signal are synchronously collected through a sampling mechanism, and then the collected signal is pre-processed through a feature extraction method to identify and analyze the collected signal including frequency, amplitude, and phase parameters. The analyzed data is input into an adaptive threshold adjustment algorithm to dynamically calculate the optimal detection threshold; based on the calculated detection threshold, the output voltage of the residual voltage step-down power supply module is dynamically adjusted through a digital potentiometer; after the output voltage and the detection threshold are adjusted, a closed-loop feedback adjustment mechanism is triggered to collect the adjusted real-time input voltage and residual voltage signal characteristics. If the adjustment result deviates from the target setting, a secondary adjustment is triggered; if the adjustment result meets the target setting, the current adjustment process is exited.

[0019] As a further technical solution of the present invention, the working method of the adaptive threshold adjustment algorithm is as follows: if the change in the frequency, amplitude or phase parameter collected within the preset time window is lower than the preset threshold, the current optimal threshold is predicted based on historical data by a sliding average method to smooth the influence of noise; if the change in the frequency, amplitude or phase parameter collected within the preset time window is higher than or equal to the preset threshold, the signal features are pattern recognized by a support vector machine to calculate the optimal detection threshold under the current working condition; the support vector machine first maps the input signal features from the original space to a high-dimensional feature space through a kernel function, and then performs model training by training a signal feature data set containing known categories, classifies the new input signal features, and determines the category of the input signal features, including normal working conditions, short circuit, and open circuit; when calculating the optimal detection threshold, the support vector machine counts the distribution of signal features of each category according to the classification results, including the mean and variance, and calculates the detection threshold with the minimum false alarm rate or missed alarm rate that can maximize the detection accuracy under the current working condition through a threshold calculation method based on statistics.

[0020] Based on the above technical solution, the positive and beneficial effects of the present invention are:

[0021] 1. The present invention designs a residual voltage step-down power supply module, which can draw power and generate a stable 5V power supply under the normal power supply voltage of the line or the residual voltage generated during a fault, thereby ensuring that the intelligent feeder terminal can continue to work and accurately capture the residual voltage signal when there is no backup power supply or the backup power supply fails. This improvement solves the problem that traditional feeder terminals cannot accurately detect residual voltage signals under special circumstances, and improves the ability to capture and record residual voltage signals.

[0022] 2. The residual voltage signal interlocking holding module and the residual voltage signal isolation output module of the present invention can quickly respond to and stably transmit the residual voltage signal through the optical coupling isolation technology, ensuring that the action time of the detection circuit is less than 40 milliseconds (ms), meeting the requirements for response time in practical applications. At the same time, the voltage threshold calibration module can dynamically adjust the output voltage and feedback-adjust the residual voltage detection threshold through the adaptive threshold adjustment algorithm and the digital potentiometer, ensuring that the action voltage is within the specified 30%U (U is usually 100V or 220V) range, thereby improving the accuracy and stability of the detection.

[0023] 3. The traditional residual voltage detection circuit uses a transformer for voltage conversion and power output, and has poor adaptability to the input voltage. However, the present invention uses the adaptive threshold adjustment algorithm of the voltage threshold calibration module to dynamically adjust according to the input voltage and residual voltage signal characteristics in real time, thereby enhancing the adaptability of the detection circuit to input voltage changes. In addition, the collaborative work of the residual voltage step-down power supply module and the voltage threshold calibration module can ensure the stability and accuracy of the output voltage, further improving the stability and reliability of the detection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a principle block diagram of the present invention;

[0025] Figure 2 It is a schematic diagram of the residual voltage step-down power-taking circuit of the present invention;

[0026] Figure 3 It is a schematic diagram of the residual voltage signal interlocking holding circuit of the present invention;

[0027] Figure 4 It is a schematic diagram of the residual voltage signal isolation output circuit of the present invention;

[0028] Figure 5 It is a schematic diagram of a residual voltage signal reset circuit of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In the present invention, a residual voltage detection circuit based on an intelligent feeder terminal includes: a residual voltage step-down power supply module, a residual voltage signal interlocking holding module, a residual voltage signal isolation output module, a residual voltage signal reset module and a voltage threshold calibration module; Figure 1As shown, this embodiment includes a residual voltage step-down power supply circuit, a residual voltage signal interlocking holding circuit, a residual voltage signal isolation output circuit and a residual voltage signal reset circuit. Among them, the residual voltage step-down power supply circuit is realized by two wide-range power supply ACDC power supply modules. The power supply module meets the line voltage greater than 30% Un and can stably output 5V power within a time range of 2 cycles. The two power modules draw power from the incoming and outgoing terminals of the circuit breaker respectively, and generate corresponding residual voltage signals while supplying power to the residual voltage detection circuit, and output them to the residual voltage signal interlock holding circuit; the residual voltage signal interlock holding circuit uses two magnetic latching relays with two sets of conversion contacts to record the residual voltage information of the incoming and outgoing terminals of the circuit breaker respectively, and the action circuits of the two magnetic latching relays are respectively connected in series with the normally closed contacts of a set of conversion contacts of another magnetic latching relay. When a residual voltage signal of a certain channel is detected, the corresponding magnetic latching relay is actuated, thereby cutting off the action circuit of the other magnetic latching relay to realize the interlocking function; the residual voltage signal isolation output circuit, i.e., the residual voltage signal reset circuit, uses the most basic optocoupler input and output isolation circuit to realize the isolation function between the control system and the residual voltage detection circuit, thereby improving the overall safety and anti-interference performance of the equipment.

[0031] In the specific implementation, the residual voltage step-down power supply module adopts the wide-range power supply ACDC power supply module of the WPS-ACDC-5V-30%-2C model. The module has a wide input voltage range of 30% Un to 100% Un, and can stably output 5V DC power when the grid voltage fluctuates greatly. At the same time, the module has a fast start-up time of ≤2 cycles and a high efficiency of ≥85%, ensuring that the residual voltage detection circuit can start quickly and work stably in a complex and changeable grid environment. The two WPS-ACDC-5V-30%-2C power supply modules respectively take power from the incoming and outgoing terminals of the circuit breaker to provide stable energy guarantee for the residual voltage detection circuit. The residual voltage signal interlock holding module adopts the MMR-2C-5V magnetic latching relay, which has a rated voltage of 5V DC and two sets of conversion contacts. It can quickly act when the residual voltage signal is detected, cut off the action circuit of the other relay, and realize the interlocking function. The action time and release time of the MMR-2C-5V relay are both no more than 10ms, ensuring the rapid response and processing of the residual voltage signal. At the same time, the relay has stable electrical performance and a long service life, which improves the reliability and stability of the residual voltage detection circuit. The VTCM-5V-ADJ voltage threshold calibration module is adopted, which has an adjustable threshold range of 0V to 5V and a high accuracy of ±1%, and can accurately calibrate the threshold of the residual voltage signal according to actual needs. At the same time, the VTCM-5V-ADJ module has a temperature coefficient of ≤0.01% / ℃, which can maintain stable calibration performance under different temperature environments. This design not only improves the accuracy of residual voltage detection, but also enhances the sensitivity of the circuit to the residual voltage signal, ensuring the reliability of the detection results. The OPI-ISO-5V optocoupler input and output isolation circuit is adopted, which has an input voltage of 5V DC and an isolation voltage of ≥2500V AC, and can realize electrical isolation between the control system and the residual voltage detection circuit. The transmission delay of the OPI-ISO-5V circuit does not exceed 5μs, and the transmission efficiency is ≥90%, ensuring the fast and accurate transmission of the residual voltage signal. At the same time, the reset module monitors the status of the residual pressure signal. When it detects that the signal disappears or returns to the normal range, it triggers the reset action to restore the MMR-2C-5V magnetic latching relay to its initial state and prepare for the next detection.

[0032] The residual voltage step-down power supply module is used to generate a 5V power supply by utilizing the residual voltage generated by the normal power supply voltage of the line or the line failure, and obtain the corresponding residual voltage signal to output to the residual voltage signal interlocking and maintaining module; wherein, the residual voltage step-down power supply module adopts two wide-range isolated ACDC power supply modules at the input and output ends of the line respectively; when the line voltage of the residual voltage step-down power supply module fluctuates, the two wide-range isolated ACDC power supply modules monitor the input voltage changes in real time through the wide-range input voltage detection and adjustment mechanism, and adjust the power conversion strategy to meet the line voltage greater than 30%Un and stably output 5V power within a time range of 2 cycles to supply power to the residual voltage signal interlocking and maintaining module; further, when extracting electric energy, the residual voltage step-down power supply module monitors the residual voltage of the line in real time through a voltage divider network and a fast comparator. If the residual voltage signal is detected to exceed the preset threshold, the signal capture mechanism is triggered to amplify, shape and filter the residual voltage signal to eliminate noise interference. Figure 2 As shown, the residual voltage step-down power supply module of this embodiment is implemented by two wide-range power supply ACDC power supply modules. The power supply at the incoming end of the circuit breaker is protected by the varistor RV1, and is connected to the customized ACDC power supply module U1 after full-wave rectification by the rectifier bridge D1, generating the residual voltage signal AB_CY at the incoming end; the power supply at the outgoing end of the circuit breaker is protected by the varistor RV2, and is connected to the customized ACDC power supply module U2 after full-wave rectification by the rectifier bridge D3, generating the residual voltage signal CB_CY at the incoming end; AB_CY and CB_CY are connected together through the switching diodes D2 and D5, which is the 5V power supply for the entire residual voltage detection circuit. D4 in the figure is a TVS tube, which is used to clamp the output signal of the power module at a lower voltage value to prevent overvoltage from damaging the subsequent circuit; C1 is a filter capacitor, which improves the stability of the output power of the two ACDC power supply modules. Among them, the customized ACDC power supply module can meet the line voltage greater than 30% Un and can stably output 5V power supply within a time range of 2 cycles; the relevant startup circuit parameters of the module can be adjusted to obtain the required output response voltage, such as 40% Un, 50% Un, etc., to meet actual application requirements.

[0033] In a specific embodiment, the residual voltage step-down power module takes power from the incoming and outgoing ends of the line through two wide-range isolated ACDC power modules, respectively, to ensure that a 5V power supply can be stably output even in the case of large voltage fluctuations. The two power modules adopt advanced wide-range input voltage regulation technology, which can accept a wider input voltage range (such as 24V to 380V), greatly enhancing the adaptability to different input voltage conditions. Each wide-range isolated ACDC power module integrates a high-precision voltage monitoring unit to evaluate the input voltage level in real time. These power modules not only have fast response characteristics, can quickly adjust the power conversion strategy when the input voltage changes, but also can stably output 5V power within a two-cycle time range. Specifically, the power module uses a special PWM control chip (for example, a high-efficiency synchronous rectification controller with model "ADP1051"), which can dynamically adjust the switching frequency and duty cycle according to the real-time monitored input voltage to achieve optimal conversion efficiency and stability. This design ensures that a stable 5V output can be maintained even in the case of large voltage fluctuations, thereby providing reliable power support for the subsequent residual voltage signal interlocking retention module. In order to cope with the complex power grid environment, the residual voltage step-down power supply module has a built-in wide-range input voltage detection and adjustment mechanism. The core of this mechanism is that it can monitor the changes in input voltage in real time and dynamically adjust the power conversion strategy according to the actual situation. Specifically, the power module is equipped with a high-precision ADC (analog-to-digital converter) and a DSP (digital signal processor) for real-time acquisition and processing of input voltage data. The ADC converts the analog voltage signal into a digital signal and passes it to the DSP for analysis. The DSP executes the corresponding algorithm according to the current voltage condition, calculates the optimal power conversion parameters, and feeds back to the PWM control chip through the SPI communication protocol to achieve precise voltage regulation. The significance of this wide-range input voltage detection and adjustment mechanism is that it enables the power module to respond quickly and reliably when facing transient voltage fluctuations, avoiding system failures caused by voltage instability. In addition, this mechanism also improves the robustness and adaptability of the system, ensuring that the output voltage remains stable regardless of how the input voltage changes, providing a solid technical guarantee for the continuous operation of the system.

[0034] In order to accurately capture the residual voltage signal in the line, the residual voltage step-down power supply module introduces the design of a voltage divider network and a fast comparator. The voltage divider network consists of a group of precision resistors, which are used to scale down the line voltage to a level suitable for subsequent processing. Specifically, the voltage divider network reduces the line voltage to about a few volts, which is convenient for the fast comparator to make a judgment. The fast comparator (LM339) is used to monitor the voltage signal after voltage division in real time. Once the residual voltage signal is detected to exceed the preset threshold, the signal capture mechanism is triggered. The working principle of the fast comparator is based on its internal differential amplifier structure, which can quickly respond to changes in input voltage. When the input voltage exceeds the set threshold, the comparator immediately flips the output state and generates a trigger pulse. This trigger pulse is passed to the subsequent signal processing circuit to start the amplification, shaping and filtering of the residual voltage signal. In this way, the system can capture the transient residual voltage signal in a very short time and further process it, thereby improving the speed and accuracy of residual voltage detection. The combination of the voltage divider network and the fast comparator not only ensures the timely capture of the residual voltage signal, but also eliminates noise interference, ensuring the purity and reliability of the signal.

[0035] Once the fast comparator detects that the residual voltage signal exceeds the preset threshold, the signal capture mechanism is triggered. It is designed to amplify, shape and filter the original residual voltage signal, eliminate noise interference, and finally generate a clean residual voltage signal output. Specifically, the signal capture mechanism first amplifies the original residual voltage signal through a low-noise dual-channel op amp (OPA2376) to improve the signal-to-noise ratio. Then, the signal enters the shaping circuit, and the excessive peak voltage is removed through the limiter and clamp circuit to ensure that the signal amplitude is within a reasonable range. Finally, the filtering circuit (MAX274) is used to eliminate high-frequency noise components, retain useful low-frequency signal components, and ensure the purity and stability of the signal. The application of the signal capture and processing mechanism significantly improves the quality of the residual voltage signal, enabling the subsequent residual voltage locking logic and other distribution automation logic to more accurately identify and process residual voltage events. Through this series of sophisticated signal processing steps, the system can not only work reliably in a complex power grid environment, but also ensure the accurate capture and processing of residual voltage signals, thereby improving the performance and reliability of the overall system.

[0036] In practical applications, the installation and connection of the residual voltage step-down power supply module need to follow strict electrical specifications and technical requirements to ensure the safety and reliability of the system. First, two wide-range isolated ACDC power modules are powered from the incoming and outgoing terminals of the circuit breaker respectively to ensure that the system can provide continuous and stable 5V power supply under any circumstances. The input end of the power module is connected to the line through a dedicated terminal block, and the output end is powered by the residual voltage signal interlock holding module through a standard 5V DC interface. In order to realize the functions of the voltage divider network and the fast comparator, a set of precision resistors and a fast comparator circuit are connected to the output end of the power module. These components are connected together through the traces on the PCB board to form a complete residual voltage monitoring loop. The resistance value of the voltage divider network is selected according to actual needs. For example, a combination of 1MΩ and 10kΩ resistors can be selected to achieve a 1:100 scaling ratio. The reference voltage of the fast comparator can be set by an external adjustable potentiometer to ensure that it can sensitively respond to changes in the residual voltage signal. The signal capture and processing mechanism is realized by a high-gain operational amplifier, shaping circuit and filtering circuit integrated on the PCB board. These circuit elements are connected by microstrip lines on multi-layer PCB boards to ensure low signal transmission loss and anti-interference performance.

[0037] The residual pressure signal interlocking and holding module is used to hold the residual pressure signal detected on the incoming line side or the outgoing line side that exceeds the threshold range and output the dry contact information to the residual pressure signal isolation output module; the working method of the residual pressure signal interlocking and holding module is as follows: when the residual pressure step-down power supply module successfully extracts the 5V residual pressure power supply signal at the incoming line end or the outgoing line end, and at the same time detects the residual pressure signal that exceeds the preset threshold range, a priority action decision is made according to the sequence of the residual pressure signal sources through the timestamp recording and comparison method; if the incoming line side first generates a 5V residual pressure power supply signal accompanied by a residual pressure signal that exceeds the threshold, The first set of switching contacts of the magnetic latching relay is activated to maintain the residual voltage signal on the incoming line and output it to the residual voltage signal isolation output module. When the incoming line switching contacts of the magnetic latching relay are activated, the second set of switching contacts of the magnetic latching relay is disconnected through the internal interlocking mechanism to lock the residual voltage signal output on the outgoing line. If the outgoing line first generates a 5V residual voltage power supply signal accompanied by a residual voltage signal exceeding the threshold, the second set of switching contacts of the magnetic latching relay is activated to maintain the residual voltage signal on the outgoing line and output it to the residual voltage signal isolation output module. At the same time, the first set of switching contacts of the magnetic latching relay is disconnected to lock the incoming line signal output.

[0038] like Figure 3As shown, the residual voltage signal interlock holding module of this embodiment is implemented by two magnetic latching relays. The residual voltage signal generated by the residual voltage step-down power supply module is a driving signal close to the power supply voltage. The residual voltage signal AB_CY is connected to the positive pole 1 pin of the driving end of the magnetic latching relay RLY1, and the negative pole 16 pin of the driving end of RLY1 is connected to the common terminal 13 pin of the normally closed contact of its own second group of conversion contacts, and then from the normally closed contact 11 pin to the normally closed contact 6 pin of the first group of conversion contacts of RLY2, and the common terminal 4 pin of the normally closed contact of the first group of conversion contacts of RLY2 is connected to the common ground of the system, thereby forming a driving circuit of RLY1; when RLY2 is not in action, its normally closed contact is in a closed state. At this time, if the residual voltage signal is generated at the power supply input end, AB_CY generates a stable signal of about 5V, and RLY1 forms a driving circuit action through its own normally closed contact and the normally closed contact of RLY2, and the normally open contact 8 pin of the first group of conversion contacts outputs a low level to the residual voltage signal isolation output circuit. Similarly, the residual voltage signal CB_CY is connected to the positive pole 1 pin of the driving end of the magnetic latching relay RLY2, the negative pole 16 pin of the driving end of RLY2 is connected to the normally closed contact common terminal 13 pin of its own second group of switching contacts, and then connected from the normally closed contact pin 11 to the normally closed contact pin 6 of the first group of switching contacts of RLY1, and the normally closed contact common terminal 4 pin of the first group of switching contacts of RLY1 is connected to the common ground of the system, thereby forming a driving circuit for RLY2; when RLY1 is not in action, its normally closed contact is in a closed state. At this time, if a residual voltage signal is generated at the power input end, CB_CY generates a stable signal of about 5V, and RLY2 forms a driving circuit through its own normally closed contact and the normally closed contact of RLY1, and the normally open contact pin 8 of the first group of switching contacts outputs a low level to the residual voltage signal isolation output circuit.

[0039] If residual pressure is generated on the incoming side of the line, the residual pressure signal AB_CY will give priority to driving RLY1 to operate and output the CY_AB_OUT signal. At this time, the normally closed contacts of the second group of conversion contacts of RLY1 become normally open contacts, thus cutting off its own drive circuit, and RLY1 enters the magnetic latching output state and no longer generates any power consumption. At the same time, the drive circuit of RLY2 is also cut off, and the system enters the interlocking state. When the system detects that there is a residual pressure signal detection at the incoming end, the residual pressure signal detection function at the outgoing end is blocked; similarly, if residual pressure is generated on the outgoing side of the line, the residual pressure signal CB_CY will give priority to driving RLY2 to operate and output the CY_CB_OUT signal. At this time, the normally closed contacts of the second group of conversion contacts of RLY2 become normally open contacts, thus cutting off its own drive circuit, and RLY2 enters the magnetic latching output state and no longer generates any power consumption. At the same time, the drive circuit of RLY1 is also cut off, and the system enters the interlocking state. When the system detects that there is a residual pressure signal detection at the outgoing end, the residual pressure signal detection function at the incoming end is blocked.

[0040] Finally, connect the positive pin 2 of the reset coils of the two relays RLY1 and RLY2 to a 5V power supply, and the negative pin 15 to the residual voltage signal reset circuit. When the system completes the residual voltage locking logic and the distribution automation related logic, and detects a power failure, it immediately sends a reset signal to reset the two relays at the same time, restoring the residual voltage detection circuit to its initial state to enter the next round of residual voltage detection.

[0041] Diodes D6, D7, and D8 are freewheeling diodes used in conjunction with the relay coil when the magnetic latching relay is driven and reset. They can eliminate the reverse voltage generated by the coil when the relay is turned off, thereby improving the stability of the system.

[0042] The residual pressure signal isolation output module is used to output the output result of the residual pressure signal interlocking holding module to the system processor through optocoupler isolation; the residual pressure signal isolation output module is based on the dry contact information output by the residual pressure signal interlocking holding module, and first identifies and receives the dry contact information through an optocoupler isolation circuit. If there are abnormal residual pressure signals in some contact information, the optocoupler isolation circuit uses an isolation mechanism and a photocoupler to convert the electrical signal at the input end into an optical signal, and then restores the optical signal to an electrical signal through a phototransistor and outputs it to the system processor.

[0043] like Figure 4 As shown, the residual pressure signal isolation output module of this embodiment is implemented with two optocouplers. Optocoupler isolation can completely isolate the input and output ends, effectively prevent signal interference and transmission, and ensure stable signal quality. When a residual pressure signal is generated at the input end of the device, relay RLY1 is activated and outputs the CY_AB_OUT signal as a low level. At this time, the optocoupler D9 is turned on through the current limiting resistor R2 to drive the opposite side to turn on, and the DI_CY_AB signal is pulled low and output to the system IO; similarly, when a residual pressure signal is generated at the output end of the device, relay RLY2 is activated and outputs the CY_CB_OUT signal as a low level. At this time, the optocoupler D10 is turned on through the current limiting resistor R4 to drive the opposite side to turn on, and the DI_CY_CB signal is pulled low and output to the system IO.

[0044] In a specific embodiment, the optocoupler isolation circuit converts the electrical signal at the input end into an optical signal through the optocoupler 6N137, and then restores the optical signal to an electrical signal through the phototransistor and outputs it to the system processor. This design not only provides electrical isolation, but also effectively eliminates noise interference and ensures the purity of the signal. 6N137 is a high-speed optocoupler widely used in the field of industrial control. It has low propagation delay (typical value is 2.5μs), high common mode rejection ratio (>10kV / μs) and a wide operating temperature range (-40℃ to +85℃), which makes it very suitable for signal transmission in high-voltage environments. The light-emitting diode (LED) inside the optocoupler is turned on or off according to the change of the received dry contact state, thereby triggering the corresponding phototransistor response. This process realizes the isolation and transmission of signals by converting optical signals into electrical signals, so that the stable operation of the system can be guaranteed even in high-voltage environments. In addition, in order to further enhance the anti-interference ability of the signal, the module integrates a filter circuit and a transient voltage suppression (TVS) diode to effectively remove high-frequency noise and transient spikes to ensure the purity of the signal. For example, using the bidirectional TVS diode model "PESD2CAN", its maximum peak pulse current can reach 8A and the clamping voltage is ±24V, which can effectively protect the optocoupler from overvoltage damage.

[0045] The residual pressure signal isolation output module first needs to identify and receive the dry contact information from the residual pressure signal interlock holding module. Dry contact is a common switch interface, usually used to connect two circuits without sharing a common ground wire, so it is particularly suitable for electrical isolation applications. The dry contact information in the present invention is provided by a magnetic latching relay. When a residual pressure signal of a certain channel is detected, the corresponding magnetic latching relay is activated to generate a state change of a switch closed or opened.

[0046] In order to accurately identify and receive dry contact information, an 8-channel level converter TXB0108 is used inside the module. The converter can quickly and reliably convert between different logic levels, ensuring that the state changes of the dry contacts can be accurately captured. At the same time, a high-precision ADC (analog-to-digital converter) is installed in the module for real-time acquisition of dry contact status, combined with DSP (digital signal processor ADS1256) for data analysis to ensure that each state change can be accurately recorded. Once the abnormal residual voltage signal is identified in the dry contact information, the optocoupler isolation circuit immediately starts the isolation mechanism. At this time, the optocoupler converts the electrical signal at the input end into an optical signal, and then restores the optical signal to an electrical signal through a phototransistor and outputs it to the system processor. In this process, the optocoupler plays a key isolation role, ensuring that the abnormal signal will not affect the subsequent circuit. For example, when an abnormal residual voltage signal is detected, the LED in the optocoupler is quickly turned on, emitting a light signal, triggering the phototransistor to turn on, thereby transmitting the abnormal signal to the system processor.

[0047] In order to ensure the reliability and security of signal transmission, a redundant design is also integrated into the module. Specifically, each channel is equipped with an independent optocoupler and signal processing unit, which can automatically switch to the backup channel when the main channel fails to ensure the continuity of data transmission. In addition, a synchronous communication protocol such as RS485 or CAN bus is used inside the module to ensure data consistency between the two channels and avoid information loss or misjudgment due to single point failure. For example, using "MAX14827A" as an RS485 transceiver, it supports a data transmission rate of up to 20Mbps, has strong anti-electromagnetic interference capabilities, and ensures the reliability and real-time performance of data transmission.

[0048] In practical applications, the input end of the residual voltage signal isolation output module is connected to the residual voltage signal interlocking holding module through a dedicated terminal block to ensure that the dry contact information can be accurately transmitted. The selection of the input terminal should take into account its rated current and voltage parameters. For example, a terminal block with a rated current of 10A and a rated voltage of 250VAC is selected to meet the needs of industrial applications. The optocoupler isolation circuit is connected together through the microstrip line on the PCB board to form a complete signal transmission path. The distance between the optocoupler (such as 6N137) and the phototransistor should be shortened as much as possible to reduce signal transmission loss. In addition, the filter circuit and TVS diode (such as PESD2CAN) should also be installed as close to the optocoupler as possible to improve the anti-interference performance. All key components are selected from high-quality industrial-grade devices to ensure the long-term stable operation of the system. The output end is connected to the system processor through a standard digital signal interface (such as SPI or I2C) to ensure the reliability and real-time performance of data transmission. For example, using "PCA9615" as an I2C bus expander, it supports a data transmission rate of up to 1Mbps, has strong anti-electromagnetic interference capabilities, and ensures the reliability and real-time performance of data transmission.

[0049] Compared with the same type of hardware, the residual pressure signal isolation output module of the present invention adopts optocoupler isolation technology to achieve complete electrical isolation between the input and output ends, prevent electrical interference, and improve the safety and reliability of the system. In addition, the integrated filter circuit and TVS diode can effectively remove high-frequency noise and transient spikes, ensure the purity and stability of the signal, and are suitable for various harsh power grid environments. Secondly, a high-performance logic level converter and a high-precision ADC are used to ensure that the state changes of the dry contacts can be accurately captured, avoiding signal omissions or misjudgments. Each channel is equipped with an independent optocoupler and signal processing unit, which can automatically switch to the backup channel when the main channel fails to ensure the continuity of data transmission.

[0050] The residual pressure signal reset module is used to issue a residual pressure signal reset instruction immediately after the system processor has processed the residual pressure locking logic or after the device power is lost, so as to start the residual pressure detection work of the next cycle; the residual pressure signal reset module evaluates the input voltage level in real time through the voltage monitoring unit, and if the working voltage change value within the preset time window is lower than the preset threshold, the residual pressure signal is continuously output to the residual pressure signal isolation output module through the steady-state holding mechanism; if the working voltage change value within the preset time window is equal to or higher than the preset threshold, a reset pulse is sent to the residual pressure signal interlock holding module to reset the residual pressure signal interlock holding module, disconnect the current residual pressure signal output path, and start the residual pressure detection work of the next cycle.

[0051] like Figure 5As shown, the residual voltage signal reset module of this embodiment is implemented by an optocoupler. Optocoupler isolation can completely isolate the input and output ends, effectively prevent signal interference and transmission, and ensure stable signal quality. After the system participates in completing the residual voltage lockout logic and the distribution automation related logic, when a power-off state is detected, the reset signal DO_CY_RST is immediately pulled low. At this time, the optocoupler D11 drives the opposite side to turn on through the current limiting resistor R5, and the base of the NPN transistor Q1 is pulled high through the current limiting resistor R6. The transistor Q1 is turned on to drive the CY_RST signal low to reset the two relays at the same time, and restore the residual voltage detection circuit to the initial state to enter the next round of residual voltage detection work.

[0052] In a specific embodiment, the core of the residual voltage signal reset module lies in its voltage monitoring unit. The unit evaluates the input voltage level in real time through a high-precision ADC (analog-to-digital converter), and determines whether a reset operation needs to be triggered based on the operating voltage change value within a preset time window. The working principle of the voltage monitoring unit is based on continuous sampling and a fast response mechanism. It collects input voltage data at a fixed frequency (such as once per millisecond) and passes these data to a DSP (digital signal processor) for analysis. A complex algorithm runs inside the DSP to calculate the voltage change value within a preset time window. If the voltage change value is lower than the preset threshold, the system is considered to be in a steady state and the steady-state maintenance mechanism is activated; conversely, if the voltage change value is equal to or higher than the preset threshold, the reset pulse generator is triggered. For example, setting the time window to 10ms and the threshold to ±5V ensures that the system can accurately capture instantaneous voltage fluctuations and avoid misjudgment.

[0053] When the voltage monitoring unit determines that the system is in a steady state, the steady-state holding mechanism will be activated to maintain the current state unchanged and continue to output the residual voltage signal. This process is implemented through a latch, which can lock the current state after receiving a stable voltage signal, and will not change its output state even if the subsequent voltage fluctuates slightly. Specifically, the steady-state holding mechanism uses a bistable multivibrator, such as an RS flip-flop (for example, a dual D-type flip-flop with model "74HC74"). The RS flip-flop has two stable states and can switch between the two states according to changes in the input signal. Once a stable state is entered, its output state will not change unless affected by an external trigger signal. This design ensures that a stable residual voltage signal output can be maintained even in the case of slight voltage fluctuations, improving the reliability and stability of the system.

[0054] When the voltage monitoring unit detects that the change value of the working voltage within the preset time window is equal to or higher than the preset threshold, the reset pulse generator is immediately started and sends a reset pulse to the residual voltage signal interlock holding module. This process is implemented by a dedicated reset instruction generator (Reset Pulse Generator), which is based on a fast response mechanism and can generate and send reset pulses in a very short time. For example, "MAX813L" is used as a reset controller, and its built-in watchdog timer can quickly send a reset pulse when a voltage abnormality is detected to ensure timely response of the system. The reset pulse is transmitted to the residual voltage signal interlock holding module through a high-speed communication protocol (such as SPI or I2C), forcing it to reset, disconnect the current residual voltage signal output path, and prepare to enter the next detection cycle. In order to ensure the reliable transmission of the reset instruction, a redundant design is integrated in the module. Each channel is equipped with an independent reset instruction generator and communication interface, which can automatically switch to the backup channel when the main channel fails to ensure the continuity of data transmission. In addition, a synchronous communication protocol (such as RS485 or CAN bus) is used inside the module to ensure data consistency between the two channels and avoid information loss or misjudgment caused by single point failure.

[0055] In practical applications, the installation and connection of the residual voltage signal reset module need to follow strict electrical specifications and technical requirements to ensure the safety and reliability of the system. First, the input end of the voltage monitoring unit is connected to the line through a dedicated terminal to ensure that the input voltage data can be collected in real time. The selection of the terminal should take into account its rated current and voltage parameters. For example, a terminal with a rated current of 10A and a rated voltage of 250VAC is selected to meet the needs of industrial applications. The steady-state holding mechanism is implemented through the latch circuit on the PCB board to ensure that the residual voltage signal is continuously output under normal power supply conditions. The latch circuit uses a bistable multivibrator (such as a 74HC74 dual D-type flip-flop) and is connected together through microstrip lines on a multi-layer PCB board to form a complete signal transmission path. All key components are selected from high-quality industrial-grade devices, such as ADS1256 ADC, 74HC74 flip-flop, etc., to ensure long-term stable operation of the system. The reset pulse generation and transmission mechanism is implemented through a reset controller (such as MAX813L) integrated on the PCB board and a high-speed communication interface (such as SPI or I2C). These circuit components are connected by microstrip lines on multi-layer PCB boards to ensure low signal transmission loss and anti-interference performance. All key components are high-quality industrial-grade devices, such as MAX813L reset controller, PCA9615 I2C bus expander, etc., to ensure long-term stable operation of the system.

[0056] Compared with similar hardware, the residual voltage signal reset module adopts high-precision ADC and fast response mechanism to ensure the accuracy and real-time performance of voltage monitoring, and can capture instantaneous voltage fluctuations in time to avoid misjudgment. In addition, the steady-state holding mechanism is realized through latches and bistable multivibrators to ensure the continuous output of residual voltage signals under normal power supply conditions, thereby improving the reliability and stability of the system. The use of reset controller and high-speed communication protocol can generate and send reset pulses in a very short time, ensuring that the system responds to voltage abnormalities in time and avoids protection failure. Each channel is equipped with an independent reset instruction generator and communication interface, which can automatically switch to the backup channel when the main channel fails, ensuring the continuity of data transmission and enhancing the robustness of the system.

[0057] The voltage threshold calibration module is used to dynamically adjust the output voltage of the residual voltage step-down power supply module by using a digital potentiometer through an adaptive threshold adjustment algorithm according to the real-time input voltage and residual voltage signal characteristics, and at the same time feedback adjust the residual voltage detection threshold. The working method of the voltage threshold calibration module is: first, the input voltage and residual voltage signal are synchronously collected through a sampling mechanism, and then the collected signal is pre-processed through a feature extraction method to identify and analyze the collected signal including frequency, amplitude, and phase parameters. The analyzed data is input into the adaptive threshold adjustment algorithm to dynamically calculate the optimal detection threshold; based on the calculated detection threshold, the output voltage of the residual voltage step-down power supply module is dynamically adjusted through a digital potentiometer; after the output voltage and the detection threshold are adjusted, the closed-loop feedback adjustment mechanism is triggered to collect the adjusted real-time input voltage and residual voltage signal characteristics. If the adjustment result deviates from the target setting, a secondary adjustment is triggered; if the adjustment result meets the target setting, the current adjustment process is exited. Furthermore, the working method of the adaptive threshold adjustment algorithm is as follows: if the change in the frequency, amplitude or phase parameters collected within the preset time window is lower than the preset threshold, the current optimal threshold is predicted based on historical data through the sliding average method to smooth the noise influence; if the change in the frequency, amplitude or phase parameters collected within the preset time window is higher than or equal to the preset threshold, the signal features are pattern recognized by the support vector machine to calculate the optimal detection threshold under the current working condition; the support vector machine first maps the input signal features from the original space to the high-dimensional feature space through the kernel function, and then trains the model by training a signal feature data set containing known categories, classifies the new input signal features, and determines the category of the input signal features, including normal working conditions, short circuit, and open circuit; when calculating the optimal detection threshold, the support vector machine counts the distribution of signal features of each category according to the classification results, including the mean and variance, and calculates the detection threshold with the minimum false alarm rate or missed alarm rate that can maximize the detection accuracy under the current working condition through the threshold calculation method based on statistics.

[0058] In a specific embodiment, the voltage threshold calibration module first synchronously collects the input voltage and residual voltage signals through a high-precision sampling circuit. The sampling circuit uses a high-speed ADC (analog-to-digital converter), such as AD7920, with a sampling rate of up to 1MSPS and a resolution of up to 16 bits, ensuring accurate capture of the signal. The collected signal is then sent to a feature extraction module, which uses digital signal processing (DSP) technology, such as TI's TMS320F28335 DSP, to pre-process the signal and identify and analyze the frequency, amplitude and phase parameters of the signal. These parameters are the basis for the subsequent adaptive threshold adjustment algorithm.

[0059] The adaptive threshold adjustment algorithm is responsible for dynamically calculating the optimal detection threshold based on the real-time input voltage and residual voltage signal characteristics. The algorithm combines the sliding average method and support vector machine (SVM) technology to flexibly adjust the threshold setting according to the signal characteristics under different working conditions to ensure the best performance of the system.

[0060] When the change in the preset time window is lower than the preset threshold, the algorithm uses the sliding average method to predict the current optimal threshold based on historical data to smooth out the noise. The sliding average method takes the average value of the data over a period of time, eliminating the impact of short-term fluctuations and making the threshold more stable and smooth. For example, using a sliding window size of 10 sample points can effectively reduce the interference of random noise and ensure the rationality of threshold setting.

[0061] For the case where the change in the preset time window is greater than or equal to the preset threshold, the algorithm uses a support vector machine to perform pattern recognition on the signal features and calculate the optimal detection threshold under the current working condition. The support vector machine first maps the input signal features from the original space to the high-dimensional feature space through a kernel function (such as the RBF kernel function), and then trains the model by training a signal feature data set containing known categories to classify the new input signal features. For example, using the "LIBSVM" library for support vector machine training can efficiently process large-scale data sets and provide powerful classification capabilities. When calculating the optimal detection threshold, the support vector machine will count the distribution of signal features of each category (such as mean, variance) based on the classification results, and calculate the detection threshold that can maximize the detection accuracy under the current working condition through a threshold calculation method based on statistics (such as the minimum false alarm rate or false negative rate).

[0062] The significance of the adaptive threshold adjustment algorithm is that it can dynamically adjust the threshold setting according to different working conditions to ensure that the system maintains optimal performance throughout the entire operating range. In this way, the system can not only respond quickly and reliably to transient changes, but also maintain a high degree of accuracy and stability in a complex power grid environment.

[0063] Based on the calculated detection threshold, the voltage threshold calibration module dynamically adjusts the output voltage of the residual voltage step-down power module through a digital potentiometer. As a programmable resistor element, the digital potentiometer allows its resistance to be accurately set through software instructions, thereby changing the output voltage level. For example, the "DS1803" dual-channel digital potentiometer is used, which has a total resistance range of 10kΩ and a resolution of 256 levels, which can provide extremely fine voltage adjustment capabilities.

[0064] The working principle of the digital potentiometer is to receive control instructions from the DSP through the SPI or I2C communication protocol, dynamically adjust its internal resistance value, and then change the output voltage. Specifically, the DSP sends the corresponding control instructions to the digital potentiometer based on the new threshold calculated by the adaptive threshold adjustment algorithm, so that it adjusts to the corresponding resistance value. This design not only achieves precise voltage regulation, but also improves the flexibility and response speed of the system. In this way, the system can quickly adjust the output voltage when facing different working conditions, ensuring the accuracy and reliability of residual voltage detection.

[0065] After the output voltage and detection threshold are adjusted, the voltage threshold calibration module triggers the closed-loop feedback adjustment mechanism to collect the adjusted real-time input voltage and residual voltage signal characteristics. If the adjustment result deviates from the target setting, a secondary adjustment is triggered; if the adjustment result meets the target setting, the current adjustment process is exited. The closed-loop feedback adjustment mechanism ensures that the system is always in the best working state through continuous self-correction, thereby improving the overall operating efficiency and reliability.

[0066] In practical applications, the voltage threshold calibration module includes the following components:

[0067] Analog-to-digital converter ADS1256: 24-bit resolution, 30ksps sampling rate, wide operating temperature range (-40°

[0068] C to +85℃), and connected to DSP through SPI interface. The input end is connected to the voltage sampling point of the line to ensure that the input voltage and residual voltage signals can be collected in real time. The output end is connected to the input pin of DSP through the microstrip line on the multi-layer PCB board.

[0069] Real-time clock chip DS3231: ±2ppm accuracy, built-in crystal oscillator, I2C communication interface, connected to DSP via I2C bus, providing a stable clock source for synchronous sampling mechanism. The SCL and SDA pins are connected to the I2C interface pins of DSP respectively to ensure accurate time reference.

[0070] Digital signal processor ADSP-BF707: dual-core architecture, supports floating-point operations, built-in efficient FFT engine, wide operating temperature range (-40℃ to +85℃), as the core processing unit of the entire module, connected to high-precision ADC and digital potentiometer through SPI interface; connected to real-time clock chip and other peripheral devices through I2C interface. DSP integrates multiple filtering algorithms to ensure the accuracy and reliability of feature extraction.

[0071] Digital potentiometer DS1803: dual channels, 10kΩ total resistance, 256-level resolution, SPI communication interface, connected to DSP via SPI interface, receives control instructions from DSP, dynamically adjusts its internal resistance value to change output voltage. Two channels are connected to the output end of the residual voltage step-down power module to achieve precise adjustment of the output voltage.

[0072] Support Vector Machine (SVM) Library: The "LIBSVM" library is used for support vector machine training and classification, running on the DSP. The collected signal features are pattern recognized by calling the LIBSVM library function to calculate the optimal detection threshold under the current working conditions. The training data set is stored in an external Flash memory and connected to the DSP through the SPI interface.

[0073] MAX517 digital-to-analog converter: 12-bit resolution, fast settling time (<1μs), low power consumption, connected to DSP via SPI interface, used to convert the calculated detection threshold into an analog voltage signal output. The output of the DAC is connected to the reference voltage input of the comparator to ensure the accuracy of the threshold setting.

[0074] Comparator LM339: Quad comparator, low power consumption, fast response, input connected to the output of high-precision ADC, reference voltage input connected to the output of DAC. When the input voltage exceeds the preset threshold, the comparator flips the output state and triggers the subsequent processing logic.

[0075] High-precision ADC (for closed-loop feedback) MAX11613: 16-bit resolution, high-speed sampling rate (1MSPS), low power consumption, connected to the DSP via the SPI interface, used to monitor the adjusted input voltage and residual voltage signal characteristics in real time. The input end is connected to the output end of the residual voltage step-down power module, and the output end is connected to the input pin of the DSP to ensure that each adjustment can be accurately recorded and evaluated.

[0076] Compared with the same type of hardware, the voltage threshold calibration module of the present invention adopts high-performance ADC and precise clock source to ensure the synchronous acquisition of input voltage and residual voltage signal, and improve the accuracy and integrity of data. Through technologies such as fast Fourier transform, short-time Fourier transform and Hilbert-Huang transform, useful feature information can be extracted from complex original signals, improving the efficiency and accuracy of subsequent processing. In addition, combined with the sliding average method and support vector machine, the threshold setting can be dynamically adjusted according to different working conditions to ensure that the system maintains optimal performance within the entire working range. Secondly, precise voltage regulation is achieved through a digital potentiometer, which improves the flexibility and response speed of the system and ensures the accuracy and reliability of residual voltage detection. Through real-time monitoring and rapid response characteristics, it is ensured that the system is always in the best working state, improving the overall operating efficiency and reliability.

[0077] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that these specific embodiments are only illustrative, and those skilled in the art may omit, replace, and change the details of the above methods and systems in various ways without departing from the principles and essence of the present invention. For example, merging the above method steps so as to perform substantially the same functions in substantially the same manner to achieve substantially the same results is within the scope of the present invention. Therefore, the scope of the present invention is limited only by the appended claims.

Claims

1. A residual voltage detection circuit based on an intelligent feeder terminal, characterized in that: The residual voltage detection circuit includes a residual voltage step-down power supply module, a residual voltage signal interlocking and holding module, a residual voltage signal isolation output module, a residual voltage signal reset module and a voltage threshold calibration module; The residual voltage step-down power supply module is used to generate a 5V power supply by using the normal power supply voltage of the line or the residual voltage generated when the line fails, and obtain the corresponding residual voltage signal and output it to the residual voltage signal interlocking holding module; The residual pressure signal interlock holding module is used to hold the residual pressure signal detected on the incoming line side or the outgoing line side that exceeds the threshold range and output the dry contact information to the residual pressure signal isolation output module; The residual voltage signal isolation output module is used to output the output result of the residual voltage signal interlocking holding module to the system processor through optical coupling isolation; The residual pressure signal reset module is used to issue a residual pressure signal reset instruction immediately after the system processor processes the residual pressure locking logic or after the device power is lost, so as to start the residual pressure detection work of the next cycle; The voltage threshold calibration module is used to dynamically adjust the output voltage of the residual voltage step-down power supply module using a digital potentiometer according to the real-time input voltage and residual voltage signal characteristics through an adaptive threshold adjustment algorithm, and at the same time feedback adjust the residual voltage detection threshold.

2. According to claim 1, a residual voltage detection circuit based on an intelligent feeder terminal is characterized in that: The residual voltage step-down power supply module adopts two wide-range isolated ACDC power supply modules at the incoming and outgoing ends of the line respectively; when the line voltage of the residual voltage step-down power supply module fluctuates, the two wide-range isolated ACDC power supply modules monitor the input voltage changes in real time through the wide-range input voltage detection and adjustment mechanism, and adjust the power conversion strategy to meet the line voltage greater than 30% Un, and stably output 5V power within a time range of 2 cycles, so as to supply power to the residual voltage signal interlocking holding module.

3. The residual voltage detection circuit based on the intelligent feeder terminal according to claim 2, characterized in that: When extracting electric energy, the residual voltage step-down power extraction module monitors the line residual voltage in real time through a voltage divider network and a fast comparator. If the residual voltage signal detected exceeds a preset threshold, a signal capture mechanism is triggered to amplify, shape and filter the residual voltage signal to eliminate noise interference.

4. The residual voltage detection circuit based on the intelligent feeder terminal according to claim 1, characterized in that: The working method of the residual voltage signal interlock holding module is as follows: when the residual voltage step-down power supply module successfully extracts a 5V residual voltage power supply signal at the incoming line or the outgoing line, and simultaneously detects a residual voltage signal that exceeds a preset threshold range, a priority action decision is made according to the order of the residual voltage signal sources through a timestamp recording and comparison method; if the incoming line side first generates a 5V residual voltage power supply signal accompanied by a residual voltage signal that exceeds the threshold, the first group of switching contacts of the magnetic latching relay is activated, the residual voltage signal on the incoming line is maintained and output to the residual voltage signal isolation output module, and when the incoming line side switching contacts of the magnetic latching relay are activated, the second group of switching contacts of the magnetic latching relay is disconnected through an internal interlocking mechanism, and the residual voltage signal output on the outgoing line is locked; if the outgoing line side first generates a 5V residual voltage power supply signal accompanied by a residual voltage signal that exceeds the threshold, the second group of switching contacts of the magnetic latching relay is activated, the residual voltage signal on the outgoing line is maintained and output to the residual voltage signal isolation output module, and the first group of switching contacts of the magnetic latching relay is disconnected at the same time, and the incoming line signal output is locked.

5. The residual voltage detection circuit based on the intelligent feeder terminal according to claim 1, characterized in that: The residual pressure signal isolation output module is based on the dry contact information output by the residual pressure signal interlock holding module. The residual pressure signal isolation output module first identifies and receives the dry contact information through an optocoupler isolation circuit. If there are abnormal residual pressure signals in some contact information, the optocoupler isolation circuit uses an isolation mechanism and a photocoupler to convert the electrical signal at the input end into an optical signal, and then restores the optical signal to an electrical signal through a photosensitive transistor and outputs it to the system processor.

6. The residual voltage detection circuit based on the intelligent feeder terminal according to claim 1, characterized in that: The residual voltage signal reset module evaluates the input voltage level in real time through the voltage monitoring unit. If the working voltage change value within the preset time window is lower than the preset threshold, the residual voltage signal is continuously output to the residual voltage signal isolation output module through the steady-state holding mechanism; If the working voltage change value within the preset time window is equal to or higher than the preset threshold, a reset pulse is sent to the residual voltage signal interlock holding module to reset the residual voltage signal interlock holding module, disconnect the current residual voltage signal output path, and start the next cycle of residual voltage detection.

7. The residual voltage detection circuit based on the intelligent feeder terminal according to claim 1, characterized in that: The working method of the voltage threshold calibration module is as follows: first, the input voltage and residual voltage signal are synchronously collected through a sampling mechanism, and then the collected signal is preprocessed through a feature extraction method to identify and analyze the collected signal parameters including frequency, amplitude, and phase. The analyzed data is input into an adaptive threshold adjustment algorithm to dynamically calculate the optimal detection threshold; based on the calculated detection threshold, the output voltage of the residual voltage step-down power supply module is dynamically adjusted through a digital potentiometer; after the output voltage and the detection threshold are adjusted, a closed-loop feedback adjustment mechanism is triggered to collect the adjusted real-time input voltage and residual voltage signal characteristics. If the adjustment result deviates from the target setting, a secondary adjustment is triggered; if the adjustment result meets the target setting, the current adjustment process is exited.

8. The residual voltage detection circuit based on the intelligent feeder terminal according to claim 7, characterized in that: The working method of the adaptive threshold adjustment algorithm is as follows: if the frequency, amplitude or phase parameter change collected within the preset time window is lower than the preset threshold, the current optimal threshold is predicted based on historical data by the sliding average method to smooth the noise influence; if the frequency, amplitude or phase parameter change collected within the preset time window is higher than or equal to the preset threshold, the signal feature is pattern recognized by the support vector machine to calculate the optimal detection threshold under the current working condition; the support vector machine first maps the input signal feature from the original space to the high-dimensional feature space through the kernel function, and then performs model training by training a signal feature data set containing known categories, classifies the new input signal feature, and determines the category of the input signal feature, including normal working condition, short circuit, and open circuit; When calculating the optimal detection threshold, the support vector machine statistics the distribution of signal features of each category according to the classification results, including the mean and variance, and calculates the detection threshold with the minimum false alarm rate or missed alarm rate that can maximize the detection accuracy under the current working conditions through a threshold calculation method based on statistics.

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