Accurate zero crossing point control method for built-in relay of large-current electric energy meter

Abstract

The invention discloses an accurate zero crossing point control method for a built-in relay of a large-current electric energy meter, which relates to the technical field of power electronics and intelligent metering and comprises the following steps of: receiving a power grid voltage digital signal, determining a voltage zero crossing point by comparing symbol changes of adjacent sampling values, establishing a phase corresponding relation between voltage and current, and calculating a current phase corresponding relation; generating current zero crossing point prediction data; when a relay switching instruction is received, the specific moment of the next current zero crossing point is calculated, and the control signal sending moment is determined; a relay driving control signal is sent, the actual action completion moment of the relay is collected, the deviation from the expected zero crossing moment is calculated, and the mechanical action delay time parameter of the relay is corrected. By predicting the current zero-crossing time and considering the mechanical action delay characteristic of the relay, accurate switching of the built-in relay at the actual current zero-crossing point is achieved, meanwhile, the self-adaptive adjusting capacity is achieved, the arc energy during large-current switching is reduced, the service life of the relay is prolonged, and the reliability of the electric energy meter is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics and intelligent metering, in particular to a precise zero-crossing control method for a built-in relay of a high-current electric energy meter. BACKGROUND

[0002] Electronic switching devices in power systems are key equipment to ensure the safety and reliability of power transmission and distribution. The built-in relay of a high-current electric energy meter, as a core component of smart grid terminal equipment, plays a crucial role in realizing electric energy metering and load on-off control. Especially in high-power electric power scenarios, the reliability and service life of the relay directly affect the safe operation of the entire power distribution system. Traditional relay control technology mainly uses hardware triggering, which immediately performs on-off operation when the current exceeds the threshold or a control signal is received. This simple triggering mechanism is acceptable in small current environments, but it faces serious challenges in high-current application scenarios. Since the instantaneous value of current in an alternating current circuit changes with the phase, if the relay is switched near the current peak, strong arcs are easily generated, which not only accelerates the ablation of the contacts, but also produces radio frequency interference and significantly shortens the service life of the relay.

[0003] However, due to the mechanical action delay characteristics of the relay itself, and the fact that this delay is affected by factors such as temperature and aging degree, it is a great technical challenge to accurately control the relay to complete the switching operation at the actual zero-crossing instant of the current. In existing technologies, fixed delay methods are often used to try to switch near the zero-crossing point, or a large number of hardware detection circuits are used to directly monitor the current zero-crossing point. The former is difficult to adapt to changes in relay parameters and power grid operating conditions, and has limited accuracy; the latter increases hardware costs and system complexity, and the safety of the high-current detection circuit itself also becomes a hidden danger. In addition, existing solutions often lack effective adaptive capabilities and cannot dynamically adjust control parameters according to actual operating conditions, resulting in a gradual decrease in the accuracy of zero-crossing switching during long-term operation, which loses the initial intention of precise control. SUMMARY

[0004] In view of the above problems, the present application is proposed.

[0005] Therefore, the present application provides a precise zero-crossing control method for a built-in relay of a high-current electric energy meter, which can solve the problems mentioned in the background art.

[0006] To solve the above technical problems, the application provides the following technical scheme: a precise zero-crossing control method for a built-in relay of a large-current electric energy meter, comprising: a main control MCU receiving a power grid voltage digital signal collected and converted by an alternating voltage sampling unit, the main control MCU determining a voltage zero-crossing point by comparing the sign change of two adjacent sampling values, establishing a corresponding relationship between the voltage phase and the current phase, and generating current zero-crossing time prediction data; using the current zero-crossing time prediction data, calculating the specific time of the next current zero-crossing point when receiving a relay switching instruction, and determining the control signal sending time according to the mechanical action delay characteristic of the built-in relay; sending a relay drive control signal, and collecting the actual action completion time of the built-in relay through a light coupling isolated state detection loop after the relay action is completed, the main control MCU calculating the deviation value between the actual action completion time and the expected current zero-crossing time, and correcting the mechanical action delay time parameter of the built-in relay using the deviation value.

[0007] As a preferred scheme of the precise zero-crossing control method for the built-in relay of the large-current electric energy meter, wherein: the establishment of the corresponding relationship between the voltage phase and the current phase comprises:

[0008] Obtaining a rated power factor value of the power grid;

[0009] Calculating a theoretical phase difference between the voltage phase and the current phase according to the rated power factor value;

[0010] Collecting actual voltage phase and current phase data within multiple power grid operation cycles;

[0011] Correcting the theoretical phase difference according to the actual voltage phase and current phase data to obtain a phase offset between the voltage zero-crossing point and the current zero-crossing point.

[0012] As a preferred scheme of the precise zero-crossing control method for the built-in relay of the large-current electric energy meter, wherein: the control signal sending time is equal to the current zero-crossing specific time minus the mechanical action delay time of the built-in relay; the step of determining the control signal sending time comprises:

[0013] Obtaining a nominal mechanical action delay time of the built-in relay;

[0014] Temperature compensating the nominal mechanical action delay time according to the actual working temperature of the built-in relay;

[0015] Aging compensating the nominal mechanical action delay time according to the cumulative action number of the built-in relay;

[0016] The mechanical action delay time after temperature compensation and aging compensation is taken as the built-in relay mechanical action delay time.

[0017] As a preferred scheme of the precise zero-crossing control method of the built-in relay of the large-current electric energy meter, the temperature compensation comprises:

[0018] The current working environment temperature of the built-in relay is collected.

[0019] According to a preset temperature-delay characteristic curve, a delay time correction coefficient at the current temperature is calculated.

[0020] The nominal mechanical action delay time is multiplied by the delay time correction coefficient to obtain the mechanical action delay time after temperature compensation.

[0021] As a preferred scheme of the precise zero-crossing control method of the built-in relay of the large-current electric energy meter, the sending of the relay drive control signal comprises:

[0022] The main control MCU generates a PWM waveform drive signal at the time of sending the control signal.

[0023] The PWM waveform drive signal is transmitted to a relay drive chip through an optical coupling isolation circuit.

[0024] The relay drive chip converts the PWM waveform drive signal into a current drive signal suitable for the coil characteristics of the built-in relay.

[0025] The built-in relay is triggered to perform on-off operation through the current drive signal.

[0026] As a preferred scheme of the precise zero-crossing control method of the built-in relay of the large-current electric energy meter, the collection of the actual action completion time of the built-in relay comprises:

[0027] The timer is started at the same time when the relay drive control signal is sent.

[0028] The change of the contact state of the built-in relay is monitored through the state detection circuit.

[0029] The timer is stopped when the change of the contact state of the built-in relay is detected.

[0030] The timing value of the timer is recorded as the actual delay time of the built-in relay from receiving the drive signal to completing the action.

[0031] As a preferred scheme of the accurate zero-crossing control method of the built-in relay of the high-current electric energy meter, wherein the step of correcting the built-in relay mechanical action delay time parameter comprises:

[0032] calculating the absolute value of the deviation value;

[0033] when the absolute value of the deviation value is greater than a preset threshold, updating the built-in relay mechanical action delay time parameter according to a weighted average algorithm;

[0034] storing the updated built-in relay mechanical action delay time parameter in the non-volatile memory of the electric energy meter;

[0035] using the updated built-in relay mechanical action delay time parameter in the next relay switching operation.

[0036] To further solve the above technical problems, the present application provides the following technical scheme: an accurate zero-crossing control system of a built-in relay of a high-current electric energy meter, comprising:

[0037] a current zero-crossing prediction module for receiving the grid voltage digital signal collected and converted by the alternating voltage sampling unit through the main control MCU, determining the voltage zero-crossing point by comparing the sign change of adjacent two sampling values, establishing the correspondence between the voltage phase and the current phase, and generating current zero-crossing time prediction data;

[0038] a switching timing control module for calculating the specific time of the next current zero-crossing when receiving the relay switching instruction using the current zero-crossing time prediction data, and determining the control signal sending time according to the mechanical action delay characteristics of the built-in relay;

[0039] an execution monitoring feedback module for sending the relay drive control signal, and collecting the actual action completion time of the built-in relay through the optocoupler isolated state detection loop after the relay action is completed, the main control MCU calculating the deviation value between the actual action completion time and the expected current zero-crossing time, and correcting the built-in relay mechanical action delay time parameter using the deviation value.

[0040] A computer device comprising a memory and a processor, the memory storing a computer program, wherein the processor implements the steps of the accurate zero-crossing control method of the built-in relay of the high-current electric energy meter when executing the computer program.

[0041] A computer readable storage medium having a computer program stored thereon, the computer program being executed by a processor to implement the steps of the accurate zero-crossing control method of the built-in relay of the high-current electric energy meter.

[0042] The beneficial effects of the present application: the present application realizes accurate prediction of current zero-crossing point by establishing the correspondence between voltage phase and current phase, avoiding the complexity and safety hazards of additional large current detection circuit required by traditional methods; at the same time, considering the inherent delay characteristics of relay mechanical action, the sending time of control signal is calculated and determined accurately in advance, so that the actual action completion time of the relay is highly consistent with the current zero-crossing point, thereby significantly reducing the generation of arc; more innovatively, the present application introduces a closed-loop feedback mechanism, which dynamically adjusts the mechanical action delay parameter by monitoring the deviation between the actual action time of the relay and the expected zero-crossing point in real time, forms an adaptive control system, effectively deals with the delay changes caused by factors such as relay aging and temperature changes, and realizes unexpected long-term stable control effect. Without increasing the hardware complexity, the safety and reliability of large current switching are improved, the service life of the relay is prolonged, and important technical support is provided for the design of large current electric energy meter. BRIEF DESCRIPTION OF DRAWINGS

[0043] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0044] Figure 1 The overall flowchart of the accurate zero-crossing point control method of the built-in relay of the large current electric energy meter proposed by the present application is shown in the figure.

[0045] Figure 2 The computer device diagram in the accurate zero-crossing point control method of the built-in relay of the large current electric energy meter proposed by the present application is shown in the figure. DETAILED DESCRIPTION

[0046] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings in the specification. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0047] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0048] Embodiment 1, refer to Figure 1For an embodiment of the present application, a precise zero-crossing control method for a built-in relay of a large-current electric energy meter is provided.

[0049] S1: The master MCU receives the grid voltage digital signal collected and converted by the AC voltage sampling unit, determines the voltage zero-crossing point by comparing the sign change of adjacent two sampling values, establishes the correspondence between the voltage phase and the current phase, and generates the current zero-crossing time prediction data.

[0050] The establishment of the correspondence between the voltage phase and the current phase includes:

[0051] Obtaining the rated power factor value of the grid;

[0052] Calculating the theoretical phase difference between the voltage phase and the current phase according to the rated power factor value;

[0053] Collecting actual voltage phase and current phase data within multiple grid operation cycles;

[0054] Correcting the theoretical phase difference according to the actual voltage phase and current phase data to obtain the phase offset between the voltage zero-crossing point and the current zero-crossing point.

[0055] In a preferred embodiment of the present application, the master MCU receives the grid voltage digital signal collected and converted by the AC voltage sampling unit. Specifically, the AC voltage sampling unit continuously collects the grid voltage signal and converts it into a digital signal through an analog-to-digital converter, and the sampling frequency is preferably set to 4KHz to ensure accurate capture of voltage waveform changes. The digital signal is transmitted to the master MCU through a data bus, and the master MCU can be a processor using the FM33A048B chip of Fudan Micro, which has sufficient computing power and power performance to realize various functions of the electric energy meter.

[0056] After the master MCU receives the grid voltage digital signal, it determines the voltage zero-crossing point by comparing the sign change of adjacent two sampling values. In actual implementation, when the sign of adjacent two sampling values changes from positive to negative or from negative to positive, it is determined that a zero-crossing phenomenon has occurred. To improve detection accuracy, the present application uses a linear interpolation algorithm to calculate a more accurate zero-crossing time: when the sign change of two adjacent sampling points is detected, the accurate time of the actual zero-crossing point is calculated according to the voltage values of the two points through linear interpolation, thereby improving the zero-crossing detection accuracy to the microsecond level.

[0057] On the basis of determining the voltage zero-crossing point, the present application further establishes the correspondence between the voltage phase and the current phase and generates the current zero-crossing time prediction data. The establishment process of the correspondence includes the following steps:

[0058] The rated power factor value of the power grid is acquired. In practical applications, the value can be read from the configuration parameters of the electric energy meter or set through a system configuration interface. For a standard residential power environment, the rated power factor is generally set to 0.9.

[0059] The theoretical phase difference between the voltage phase and the current phase is calculated according to the rated power factor value. Based on the definition of the power factor, the main control MCU calculates the theoretical phase difference angle between the voltage and the current. For example, when the power factor is 0.9, the phase difference angle is about 25.8 degrees, corresponding to a time difference of about 1.43 milliseconds in a 50Hz power grid.

[0060] The actual voltage phase and current phase data are collected in multiple power grid operation cycles. In the normal operation state, the main control MCU continuously monitors the voltage and current signals in 10 power grid cycles (corresponding to 200 milliseconds at a frequency of 50Hz), records the actual zero-crossing time of the voltage and current in each cycle, and calculates the time difference between them.

[0061] The theoretical phase difference is corrected according to the actual voltage phase and current phase data to obtain the phase shift between the voltage zero-crossing point and the current zero-crossing point. The main control MCU statistically analyzes the actual phase differences collected in multiple cycles and calculates a more accurate phase shift through weighted averaging, while filtering out possible abnormal values. The corrected phase shift is used as the basis data for predicting the current zero-crossing time and is stored in the internal parameter area of the main control MCU for subsequent accurate control of the relay.

[0062] Through the above process, the present application realizes accurate prediction of the current zero-crossing point, lays a foundation for accurate switching of the built-in relay in the large-current electric energy meter at the zero-crossing point, and effectively avoids the problems of arc generation and contact ablation caused by switching at a non-zero-crossing point of the current.

[0063] S2: Using the current zero-crossing time prediction data, calculate the specific time of the next current zero-crossing point when receiving the relay switching instruction, and determine the control signal sending time according to the mechanical action delay characteristics of the built-in relay.

[0064] The control signal sending time is equal to the specific time of the current zero-crossing point minus the mechanical action delay time of the built-in relay; the step of determining the control signal sending time comprises:

[0065] Obtain the nominal mechanical action delay time of the built-in relay;

[0066] Temperature compensate the nominal mechanical action delay time according to the actual working temperature of the built-in relay;

[0067] Age compensate the nominal mechanical action delay time according to the cumulative action number of the built-in relay;

[0068] The mechanical action delay time after temperature compensation and aging compensation is taken as the built-in relay mechanical action delay time.

[0069] The temperature compensation includes:

[0070] The current working environment temperature of the built-in relay is collected.

[0071] According to the preset temperature-delay characteristic curve, the delay time correction coefficient at the current temperature is calculated.

[0072] The nominal mechanical action delay time is multiplied by the delay time correction coefficient to obtain the mechanical action delay time after temperature compensation.

[0073] Specifically, when the electric energy meter master MCU receives a relay switching instruction, through a series of accurate calculations and compensation mechanisms, the built-in relay accurately performs on-off operation at the current zero-crossing point.

[0074] Firstly, the master MCU uses the current zero-crossing point prediction data generated in the foregoing steps, combined with the current system clock and power grid frequency information, to calculate the specific time of the next current zero-crossing point. In actual application, the master MCU accurately calculates the predicted arrival time of the next current zero-crossing point based on the last detected voltage zero-crossing point time, adds the corrected voltage and current phase offset, and considers the power grid cycle time (20 milliseconds for a 50Hz power grid).

[0075] Since there is a mechanical delay from when the relay receives the control signal to when it completes the physical action, in order to ensure that the relay contact switching occurs exactly at the current zero-crossing point, the master MCU needs to send the control signal in advance. The present application innovatively proposes an accurate calculation method for the control signal sending time: the control signal sending time is equal to the specific time of the current zero-crossing point minus the built-in relay mechanical action delay time.

[0076] In order to obtain accurate built-in relay mechanical action delay time, the present application considers multiple influencing factors and realizes a complete delay time compensation mechanism, the specific steps are as follows:

[0077] Firstly, the master MCU obtains the nominal mechanical action delay time of the built-in relay. This parameter is usually provided by the relay manufacturer and is the average delay time value measured under standard environmental conditions (such as 25℃ temperature, new product state). For the large current relay used in the present application, the nominal mechanical action delay time is usually in the range of 5 to 15 milliseconds.

[0078] Secondly, the master MCU compensates the nominal mechanical action delay time according to the actual working temperature of the built-in relay. The working temperature has a significant impact on the mechanical components of the relay. For example, in a low-temperature environment, the relay coil and mechanical structure may be affected by increased resistance, resulting in increased action delay; while in a high-temperature environment, certain components may become more active, resulting in a decrease in delay time. To achieve accurate temperature compensation, the present application specifically takes the following measures:

[0079] The master MCU collects the current working environment temperature of the built-in relay through a temperature sensor. The temperature sensor can be integrated inside the electric energy meter, close to the relay installation location, to obtain data closest to the actual working temperature of the relay. The temperature collection accuracy is preferably ±1℃, and the collection frequency is set to once every 1 minute.

[0080] Next, the master MCU calculates the delay time correction coefficient at the current temperature according to the preset temperature-delay characteristic curve. This characteristic curve is obtained by fitting a large amount of experimental data and reflects the variation law of the relay delay time under different temperature conditions. In one specific embodiment of the present application, the characteristic curve can be simplified as a piecewise linear function, for example, within the range of -25℃ to +55℃, each 10℃ temperature change corresponds to about 5% change in delay time.

[0081] Then, the master MCU multiplies the nominal mechanical action delay time by the calculated delay time correction coefficient to obtain the temperature-compensated mechanical action delay time. For example, if the nominal delay time is 10 milliseconds, the current temperature is 5℃, and the corresponding correction coefficient is 1.08, then the temperature-compensated delay time is 10.8 milliseconds.

[0082] In addition to temperature compensation, the present application also considers the impact of relay service life on delay time and compensates the nominal mechanical action delay time for aging. As the number of relay actions increases, the mechanical components may experience wear, spring fatigue, and other phenomena, causing changes in the action delay characteristics. The master MCU records the cumulative number of actions of the built-in relay and calculates the aging compensation coefficient according to a pre-established aging characteristic model. For example, in one specific implementation of the present application, for every 10,000 actions, the delay time increases by about 2%, up to a maximum compensation limit (e.g., 1.3 times the nominal value).

[0083] Finally, the master MCU takes the mechanical action delay time after temperature compensation and aging compensation as the actual mechanical action delay time of the built-in relay, which is used to calculate the precise control signal sending time. This dynamic compensation mechanism that considers both temperature and aging factors enables the present application to maintain high precision in relay switching under various working conditions, significantly improving the working reliability and service life of the built-in relay of the large-current electric energy meter.

[0084] S3: sending a relay driving control signal, and collecting an actual action completion time of the built-in relay through a state detection loop isolated by an optocoupler after the relay action is completed, the host MCU calculating a deviation value between the actual action completion time and an expected current zero-crossing time, and correcting a mechanical action delay time parameter of the built-in relay by using the deviation value.

[0085] The sending of the relay driving control signal comprises:

[0086] The host MCU generates a PWM waveform driving signal at the time of sending the control signal;

[0087] The PWM waveform driving signal is transmitted to a relay driving chip through an optocoupler isolation circuit;

[0088] The relay driving chip converts the PWM waveform driving signal into a current driving signal suitable for the characteristics of the built-in relay coil;

[0089] The built-in relay is triggered to perform on-off operation by the current driving signal.

[0090] The collection of the actual action completion time of the built-in relay comprises:

[0091] The timer is started at the same time as the sending of the relay driving control signal;

[0092] The state detection loop is used to monitor the change of the contact state of the built-in relay;

[0093] The timer is stopped when the change of the contact state of the built-in relay is detected;

[0094] The timing value of the timer is recorded as the actual delay time of the built-in relay from receiving the driving signal to completing the action.

[0095] The correction of the mechanical action delay time parameter of the built-in relay comprises:

[0096] The absolute value of the deviation value is calculated;

[0097] When the absolute value of the deviation value is greater than a preset threshold, the mechanical action delay time parameter of the built-in relay is updated according to a weighted average algorithm;

[0098] The updated mechanical action delay time parameter of the built-in relay is stored in the non-volatile memory of the electric energy meter;

[0099] The updated mechanical action delay time parameter of the built-in relay is used in the next relay switching operation.

[0100] At the calculated control signal sending moment, the main control MCU generates a PWM waveform driving signal. Using a PWM (pulse width modulation) signal instead of a simple level signal can more accurately control the size and duration of the driving current, ensuring that the relay reliably operates while minimizing energy consumption. In this embodiment, the frequency of the PWM driving signal is set to 20 KHz, and the duty cycle is 80%. This parameter combination can provide sufficient driving capability while reducing current impact.

[0101] The generated PWM waveform driving signal is transmitted to the relay driving chip through an optical coupling isolation circuit. Optical coupling isolation design is crucial for high-current energy meters, as it achieves electrical isolation between the control circuit and the high-current load circuit, effectively preventing damage to the main control MCU from power grid interference and surges, while ensuring high-speed and accurate transmission of signals. The present application uses a high-speed optocoupler with a response time of less than 5 microseconds, ensuring that control accuracy is not significantly affected by optocoupler transmission delays.

[0102] After receiving the PWM waveform driving signal, the relay driving chip converts it into a current driving signal suitable for the characteristics of the built-in relay coil. The driving chip selected in the present application has built-in overcurrent protection, overheat protection, and feedback detection functions, and can provide a maximum driving current of 2A, meeting the driving needs of high-current relays. The driving chip generates an optimal driving current waveform based on the rated coil resistance and inductance characteristics of the built-in relay, ensuring reliable operation of the relay while avoiding coil overheating.

[0103] The current driving signal triggers the built-in relay to perform on-off operations. In this process, the relay coil is powered to generate an electromagnetic force that overcomes the spring resistance to move the relay contacts, ultimately completing the closing or opening of the contacts. For the high-current built-in relay used in the present application, the contacts can carry a 120A on-off current, with a contact resistance of less than 3 milliohms, ensuring low loss and high reliability in a high-current environment.

[0104] To verify and optimize control accuracy, the present application designs a relay state real-time monitoring and feedback mechanism. While sending the relay driving control signal, the main control MCU starts a high-precision timer. This timer uses the hardware timer resources of the main control MCU, with a high-stability external crystal oscillator as the clock source, and a time base accuracy of better than 0.01 milliseconds, which can accurately record the time interval from control signal sending to relay action completion.

[0105] The state detection circuit monitors the change of the built-in relay contact state in real time through optical coupling isolation. The state detection circuit adopts differential detection design, and realizes high-speed and reliable detection of the contact switching state by measuring the voltage difference between the two ends of the relay contact. When the relay is in the on state, the voltage between the two ends of the contact is close to zero; when it is in the off state, there is a significant voltage difference between the two ends of the contact. The response time of the state detection circuit is less than 1 millisecond, which can timely capture the change of the relay state.

[0106] When the state detection circuit detects that the built-in relay contact state changes, the main control MCU immediately stops the timer and records the timer value as the actual delay time of the built-in relay from receiving the driving signal to completing the action. This actual delay time reflects the real action characteristics of the relay under the current working condition.

[0107] Next, the main control MCU calculates the deviation value between the actual action completion time and the expected current zero-crossing time. The expected current zero-crossing time is obtained through the current zero-crossing time prediction data in the foregoing steps, and the actual action completion time is the control signal sending time plus the actual measured delay time. By comparing the difference between the two, the system can evaluate the accuracy of the current control and provide correction basis for subsequent control.

[0108] In order to continuously optimize the control accuracy, the application realizes the adaptive correction mechanism of the built-in relay mechanical action delay time parameter. First, the system calculates the absolute value of the deviation value, that is, the absolute value of the time difference between the actual action time and the expected zero-crossing time. When the absolute value of this deviation value is greater than a preset threshold (such as 0.5 milliseconds), the system considers that there is optimization space for the current parameter, which needs to be adjusted.

[0109] The adjustment adopts a weighted average algorithm to update the built-in relay mechanical action delay time parameter. This algorithm gives a certain weight (such as 20%) to the currently measured actual delay time, and performs weighted average calculation with the original parameter (weight 80%) to obtain the updated delay time parameter. This smooth transition update strategy avoids the excessive influence of single abnormal measurement on the system, while gradually adapting to the changes of relay characteristics.

[0110] The updated built-in relay mechanical action delay time parameter is stored in the non-volatile memory of the electric energy meter. This ensures that the electric energy meter can still retain the latest parameter value after power failure, maintaining the continuous optimization ability of the system. The storage operation adopts checksum mechanism to prevent errors during data storage.

[0111] In the next relay switching operation, the system will use the updated built-in relay mechanical action delay time parameter. In this way, through continuous measurement, comparison, adjustment and optimization, the system forms a complete adaptive control closed loop, which can cope with various influencing factors such as environmental temperature changes and relay aging, and always maintains the best control accuracy.

[0112] Through the above-mentioned embodiments, the present application realizes the accurate switching control of the built-in relay of the large-current electric energy meter at the current zero-crossing point, significantly reduces the generation of electric arc, prolongs the service life of the relay, and improves the safety and reliability of the electric energy meter in the large-current environment.

[0113] Embodiment 2, as an embodiment of the present application, provides an accurate zero-crossing control system for a built-in relay of a large-current electric energy meter, comprising:

[0114] A current zero-crossing prediction module is configured to receive the grid voltage digital signal collected and converted by the alternating voltage sampling unit through the main control MCU, determine the voltage zero-crossing point by comparing the sign change of adjacent two sampling values, establish the corresponding relationship between the voltage phase and the current phase, and generate the current zero-crossing time prediction data;

[0115] A switching timing control module is configured to calculate the specific time of the next current zero-crossing point when receiving the relay switching instruction by using the current zero-crossing time prediction data, and determine the control signal sending time according to the mechanical action delay characteristic of the built-in relay.

[0116] An execution monitoring feedback module is configured to send the relay drive control signal, and collect the actual action completion time of the built-in relay through the optocoupler isolated state detection loop after the relay action is completed, calculate the deviation value between the actual action completion time and the expected current zero-crossing time by the main control MCU, and correct the built-in relay mechanical action delay time parameter by using the deviation value.

[0117] Embodiment 3, refer to Figure 2For one embodiment of the present application, different from the previous embodiment, the function, if realized in the form of a software function unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or the part of the technical solution that essentially contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in various embodiments of the present application. The aforementioned storage medium includes a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media that can store program codes.

[0118] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a list of executable instructions for implementing logic functions, which can be embodied in any computer-readable medium for use by an instruction execution system, apparatus, or device, such as a computer-based system, a system including a processor, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions, or in conjunction with these instructions execution systems, apparatuses, or devices. For the purpose of this specification, the "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by an instruction execution system, apparatus, or device, or in conjunction with these instruction execution systems, apparatuses, or devices.

[0119] More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection having one or more wires (electrical devices), a portable computer diskette (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium can even be paper or other suitable medium on which the program can be printed, as the program can be electronically obtained, for example, by optical scanning of the paper or other medium, followed by electronic editing, interpretation, or necessary processing, and then stored in a computer memory if necessary. Other suitable media can also be used.

[0120] It should be understood that portions of the present application can be implemented in hardware, software, firmware, or combinations thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, implementation can be with any or a combination of the following technologies, which are all well known in the art: a discrete logic circuit having logic gates for implementing logic functions upon an application of data signals, an application specific integrated circuit having appropriate combinational logic gates, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0121] It should be noted that the above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and all should be covered in the scope of the claims of the present application.

Claims

1. A method for accurate zero-crossing control of a built-in relay of a high-current electric energy meter, characterized in that, The application relates to a relay control method and device. The main control MCU receives the grid voltage digital signal collected and converted by an alternating voltage sampling unit, determines the voltage zero-crossing point by comparing the sign change of adjacent two sampling values, establishes the corresponding relationship between the voltage phase and the current phase, generates the current zero-crossing time prediction data, calculates the specific time of the next current zero-crossing point when receiving the relay switching instruction, and determines the control signal sending time according to the mechanical action delay characteristic of the built-in relay. The relay driving control signal is sent, and the actual action completion time of the built-in relay is collected through the state detection loop isolated by the optocoupler after the relay action is completed; the main control MCU calculates the deviation value between the actual action completion time and the expected current zero-crossing time, and corrects the mechanical action delay time parameter of the built-in relay by using the deviation value. The establishment of the corresponding relationship between the voltage phase and the current phase comprises the following steps:

2. The method for accurate zero-crossing control of built-in relay of high current electric energy meter according to claim 1, characterized in that: The rated power factor value of the grid is obtained; The theoretical phase difference between the voltage phase and the current phase is calculated according to the rated power factor value; The actual voltage phase and current phase data are collected in multiple grid operation cycles; The theoretical phase difference is corrected according to the actual voltage phase and current phase data, and the phase offset between the voltage zero-crossing point and the current zero-crossing point is obtained. The control signal sending time is equal to the current zero-crossing specific time minus the mechanical action delay time of the built-in relay; the step of determining the control signal sending time comprises the following steps:

3. The method for accurate zero-crossing control of built-in relay of high current electric energy meter according to claim 2, characterized in that: The nominal mechanical action delay time of the built-in relay is obtained; The nominal mechanical action delay time is temperature-compensated according to the actual working temperature of the built-in relay; The nominal mechanical action delay time is aging-compensated according to the cumulative action number of the built-in relay; The mechanical action delay time after temperature compensation and aging compensation is taken as the mechanical action delay time of the built-in relay. The temperature compensation comprises the following steps:

4. The method for accurate zero-crossing control of built-in relay of high current electric energy meter according to claim 3, characterized in that: The current working environment temperature of the built-in relay is collected; The delay time correction coefficient under the current temperature is calculated according to a preset temperature-delay characteristic curve; The nominal mechanical action delay time is multiplied by the delay time correction coefficient to obtain the temperature-compensated mechanical action delay time. The sending of the relay driving control signal comprises the following steps:

5. The method for accurate zero-crossing control of built-in relay of high current watt-hour meter according to claim 4, characterized in that: The main control MCU generates a PWM waveform driving signal at the control signal sending time; The PWM waveform driving signal is transmitted to the relay driving chip through the optocoupler isolation circuit; The relay driving chip converts the PWM waveform driving signal into a current driving signal suitable for the coil characteristics of the built-in relay; The built-in relay is triggered to perform on-off operation through the current driving signal. The collection of the actual action completion time of the built-in relay comprises the following steps:

6. The method for accurate zero-crossing control of built-in relay of high current watthour meter as claimed in claim 5, wherein: The timer is started at the same time when the relay driving control signal is sent; The state detection loop is used to monitor the change of the contact state of the built-in relay; The timer is stopped when the change of the contact state of the built-in relay is detected. ​ Record the timing value of the timer as the actual delay time of the built-in relay from receiving the driving signal to completing the action.

7. The method for accurate zero-crossing control of built-in relay of high current watt-hour meter as claimed in claim 6, wherein: The correction of the built-in relay mechanical action delay time parameter includes: Calculate the absolute value of the deviation value; When the absolute value of the deviation value is greater than a preset threshold, update the built-in relay mechanical action delay time parameter according to a weighted average algorithm; Store the updated built-in relay mechanical action delay time parameter in the non-volatile memory of the electric energy meter; Use the updated built-in relay mechanical action delay time parameter in the next relay switching operation.

8. An accurate zero-crossing control system for a built-in relay of a high-current electric energy meter, based on the accurate zero-crossing control method for the built-in relay of the high-current electric energy meter according to any one of claims 1 to 7, characterized in that: Comprise, The current zero-crossing prediction module is used for receiving the grid voltage digital signal collected and converted by the alternating voltage sampling unit through the main control MCU, determining the voltage zero-crossing point by comparing the sign change of adjacent two sampling values, establishing the corresponding relationship between the voltage phase and the current phase, and generating the current zero-crossing time prediction data; The switching timing control module is used for calculating the specific time of the next current zero-crossing point when receiving the relay switching instruction by using the current zero-crossing time prediction data, and determining the control signal sending time according to the mechanical action delay characteristic of the built-in relay; The execution monitoring feedback module is used for sending the relay driving control signal, and collecting the actual action completion time of the built-in relay through the opto-isolated state detection loop after the relay action is completed, calculating the deviation value of the actual action completion time and the expected current zero-crossing time by the main control MCU, and correcting the built-in relay mechanical action delay time parameter by using the deviation value. 9.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is configured to perform the method according to any one of claims 1-8 when the computer program is executed by the processor. The processor executes the computer program to realize the steps of the precise zero-crossing control method of the built-in relay of the large-current electric energy meter in any one of claims 1 to 7.

10. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to realize the steps of the precise zero-crossing control method of the built-in relay of the large-current electric energy meter in any one of claims 1 to 7.

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