Self-tuning method and device for control and protection switch
By using a load current fluctuation judgment method, the load stability state is automatically identified, enabling self-tuning of control and protection switches. This solves the problem of large errors in manual tuning in existing technologies and improves tuning accuracy and adaptability.
Patent Information
- Application Number
- CN202511851982.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-10
- Publication Date
- 2026-03-03
AI Technical Summary
The current setting and tripping level parameters of existing control and protection switches (CPS) rely on manual judgment, resulting in large errors in the setting results, low efficiency, and inability to adapt to the needs of different loads.
By adopting a load current fluctuation judgment method, the stable operating state of the load is automatically identified. The fluctuation is calculated by the ratio of standard deviation to mean, realizing the self-tuning of setting current and tripping level, ensuring setting accuracy and adaptability.
It achieves high-precision setting without human intervention, improves on-site debugging efficiency, is highly adaptable, reduces the requirements for operators, and ensures the matching of setting current and tripping level.
Smart Images
Figure CN121602285A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a setting method for a control and protective switching device (CPS), belonging to the field of low-voltage electrical technology. Background Technology
[0002] As a key electrical component integrating control, protection, and monitoring functions, CPS (Cyclic Power Supply System) is widely used in industrial power distribution systems. The parameter settings of the CPS setting current and tripping level directly determine its protection performance. An excessively low setting current can easily lead to false tripping, while an excessively high setting current will fail to effectively protect the load. Mismatched tripping levels can cause delays or premature overload protection actions. Activating the CPS with inappropriate parameters may damage the load equipment, impacting business production and residential life. Existing CPS products typically have default setting current and overload tripping level parameters at the factory. However, for different loads, these default settings may not be optimal or even suitable. Therefore, it is necessary to adaptively adjust the setting parameters according to the actual load conditions.
[0003] Currently, some manufacturers have launched CPS products with self-tuning function for setting current. When these products are used in motor-type equipment, the setting operation process requires manual judgment of the motor's operating status. After the motor has reached a stable operating state, the operator informs the equipment through buttons or knobs on the equipment, and the equipment will then use the current operating current as the setting current. In this process, the judgment of the motor's stable operating state is highly dependent on the operator's experience, which requires a high level of skill from the on-site operator. The setting result has a large error and the setting process is inefficient. Summary of the Invention
[0004] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a self-tuning method for control and protection switches, which has the advantages of being less affected by human factors, high degree of automation, high setting accuracy, excellent protection matching, and strong adaptability.
[0005] The present invention specifically adopts the following technical solutions to solve the above-mentioned technical problems: A self-tuning method for a control and protection switch, wherein the setting current is automatically adjusted when the load enters a stable operating state after the control and protection switch is started; characterized in that the following method is used to determine whether the load has entered a stable operating state: judging whether the load has entered a stable operating state based on whether the fluctuation of the load current of each phase shows a decreasing trend; the fluctuation of the load current of any phase is the ratio of the standard deviation to the mean of the load current value of that phase after the control and protection switch is started in real time; the load current value must be within the adjustment range of the setting current parameter allowed by the control and protection switch.
[0006] Preferably, the decreasing trend of volatility is determined based on n consecutive fixed periods, and the continuous decreasing gradient of volatility within the n periods is ≥ ΔK.
[0007] Furthermore, the automatic setting of the setting current specifically includes the following steps: Determine whether the load has entered a stable operating state within a specified time range after the control and protection switch is started. If so, use the maximum value of the load current in each phase at the moment of entering the stable operating state as the setting current and exit self-tuning; otherwise, exit self-tuning and use the default setting current of the control and protection switch as the setting current.
[0008] Preferably, after automatically setting the setting current, automatic setting of the overload trip level is also performed.
[0009] Furthermore, the following method is used for automatic setting of overload tripping levels: calculate the ratio of the starting heat capacity of each overload tripping level to the reference heat capacity corresponding to that overload tripping level, and select the overload tripping level whose obtained ratio is less than a preset threshold and is closest to the preset threshold as the setting value of the current overload tripping level.
[0010] Based on the same inventive concept, the following technical solutions can also be obtained: A self-tuning device for a control and protection switch includes a current setting module for automatically setting the setting current when the load enters a stable operating state after the control and protection switch is started. The current setting module determines whether the load has entered a stable operating state using the following method: judging whether the load has entered a stable operating state based on whether the fluctuation of the load current of each phase shows a decreasing trend; the fluctuation of the load current of any phase is the ratio of the standard deviation to the mean of the load current value of that phase after the control and protection switch is started, calculated in real time; the load current value must be within the adjustment range of the setting current parameter allowed by the control and protection switch.
[0011] Preferably, the decreasing trend of volatility is determined based on n consecutive fixed periods, and the continuous decreasing gradient of volatility within the n periods is ≥ ΔK.
[0012] Furthermore, the automatic setting of the setting current specifically includes the following steps: Determine whether the load has entered a stable operating state within a specified time range after the control and protection switch is started. If so, use the maximum value of the load current in each phase at the moment of entering the stable operating state as the setting current and exit self-tuning; otherwise, exit self-tuning and use the default setting current of the control and protection switch as the setting current.
[0013] Preferably, the self-tuning device of the control and protection switch further includes an overload tripping level setting module, which is used to automatically set the overload tripping level after automatically setting the setting current.
[0014] Furthermore, the overload tripping level setting module uses the following method to automatically set the overload tripping level: calculate the ratio of the starting heat capacity of each overload tripping level to the reference heat capacity corresponding to that overload tripping level, and select the overload tripping level whose ratio is less than a preset threshold and is closest to the preset threshold as the setting value of the current overload tripping level.
[0015] A control and protection switch includes a self-tuning device as described in any of the above technical solutions.
[0016] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: This invention achieves self-tuning of setting current and tripping level parameters without manual intervention by accurately identifying the load operating status during CPS startup. The setting is completed automatically through current characteristic analysis without human intervention, reducing the requirements for operators, improving on-site debugging efficiency, and achieving a high degree of automation. This invention determines the load operating status based on fluctuation, ensuring that the set current reflects the actual operating conditions and has high setting accuracy. This invention employs an adjustable start-up time, which can adapt to loads with different start-up characteristics (such as heavy-duty motors, resistive loads, etc.), and has strong adaptability. Attached Figure Description
[0017] Figure 1 This is a flowchart illustrating the self-tuning process of a specific embodiment of the present invention. Detailed Implementation
[0018] To address the shortcomings of existing CPS self-tuning technology for setting current, the present invention proposes a solution based on the dynamic current characteristics of the load. By utilizing the load current fluctuation characteristics, the load operating state is accurately identified, thereby achieving automatic setting of the setting current.
[0019] This invention uses the standard deviation and mean of the load current value to construct the fluctuation characteristics that characterize the load operating state; the fluctuation of the load current of any phase is the ratio of the standard deviation to the mean of the load current value of that phase after the control and protection switches are started in real time.
[0020] The present invention specifically adopts the following technical solutions to solve the above-mentioned technical problems: A self-tuning method for a control and protection switch, wherein the setting current is automatically adjusted when the load enters a stable operating state after the control and protection switch is started; the following method is used to determine whether the load has entered a stable operating state: whether the fluctuation of the load current of each phase shows a decreasing trend; the fluctuation of the load current of any phase is the ratio of the standard deviation to the mean of the load current value of that phase after the control and protection switch is started, calculated in real time; the load current value must be within the adjustment range of the setting current parameter allowed by the control and protection switch.
[0021] A self-tuning device for a control and protection switch includes a current setting module for automatically setting the setting current when the load enters a stable operating state after the control and protection switch is started. The current setting module determines whether the load has entered a stable operating state using the following method: judging whether the load has entered a stable operating state based on whether the fluctuation of the load current of each phase shows a decreasing trend; the fluctuation of the load current of any phase is the ratio of the standard deviation to the mean of the load current value of that phase after the control and protection switch is started, calculated in real time; the load current value must be within the adjustment range of the setting current parameter allowed by the control and protection switch.
[0022] Preferably, the decreasing trend of volatility is determined based on n consecutive fixed periods, and the continuous decreasing gradient of volatility within n periods is ≥ ΔK; n is an integer greater than 2, and ΔK is a preset gradient threshold.
[0023] Once the load reaches a stable operating state, the current can be set according to the current load current. To improve safety, the current setting must also consider load current safety limits and settling time limits. Preferably, the automatic setting of the current setting specifically includes the following steps: Determine whether the load has entered a stable operating state within a specified time range after the control and protection switch is started. If so, use the maximum value of the load current in each phase at the moment of entering the stable operating state as the setting current and exit self-tuning; otherwise, exit self-tuning and use the default setting current of the control and protection switch as the setting current.
[0024] In the above-mentioned setting current self-setting process, in order to avoid false triggering of protection actions during the startup process and to ensure the basic safety of the load, furthermore, within the specified time range after the control and protection switch is started, the protection functions of the control and protection switch other than short circuit protection, locked rotor protection, and phase loss protection are shielded.
[0025] After the automatic setting of the setting current is completed, the overload tripping level can be further automatically set through the overload tripping level setting module. The automatic setting of the overload tripping level can adopt various existing technologies. Preferably, the overload tripping level setting module uses the following method to automatically set the overload tripping level: calculate the ratio of the starting heat capacity of each overload tripping level to the reference heat capacity corresponding to the overload tripping level, and select the overload tripping level whose ratio is less than a preset threshold and closest to the preset threshold as the setting value of the current overload tripping level.
[0026] To facilitate public understanding, the technical solution of the present invention will be described in detail below through a specific embodiment and in conjunction with the accompanying drawings: The CPS self-tuning method of this invention begins execution after the CPS is started. First, the current setting module automatically sets the setting current, and then the overload tripping level setting module automatically sets the overload tripping level. The CPS self-tuning process in this embodiment is as follows: Figure 1 As shown, the details are as follows: (1) From the start of CPS, CPS collects the three-phase load current in real time and calculates the effective value of the three-phase load current respectively; (2) All effective values of three-phase load currents collected from the start of CPS that meet the adjustment range of the setting current parameters allowed by the control and protection switches are stored in the cache; (2) Based on the effective values of the three-phase load currents within the adjustment range of the set current parameters allowed by the control and protection switches since the start of the CPS, calculate the average value of the load current of each phase within the adjustment range of the set current parameters allowed by the control and protection switches from the start of the CPS to the present at a fixed period. Standard deviation The fixed period is preferably 0.1s;
[0027] in, [i] represents the effective value of the current. N This represents the total number of phase load current values stored in the cache at the current moment that meet the adjustment range of the control and protection switch's allowable setting current parameters since the CPS startup time. Every 0.1 seconds, the average value of each phase load current within the adjustment range of the control and protection switch's allowable setting current parameters from the CPS startup time to the present is calculated using the above formula. Standard deviation ; Based on the average value of the load current mentioned above Standard deviation Calculate the fluctuation of the load current in each phase at the current moment. Etc. The calculation formula is as follows:
[0028] The fluctuation of the load current in each phase at the current moment can be obtained from the above formula. Etc. ; (3) Based on volatility Etc. Determine whether the load has reached a stable operating state at the current moment: Three-phase load current fluctuation Etc. The trend of the fluctuation of the load current is used to determine whether the load has reached a stable operating state at the current moment: if the fluctuation of the three-phase load current is decreasing, the load is considered to have reached a stable operating state; otherwise, the load is considered not to have reached a stable operating state. The trend of the fluctuation of Stb can be determined by n consecutive fixed periods. If the fluctuation of Stb continues to decrease within n periods and the decrease gradient is ≥ ΔK, then the fluctuation of Stb is considered to be decreasing. ΔK is preferably 1%, and n is preferably 3. (4) If the load has reached a stable operating state within the specified time range T, the maximum value of the load current of each phase at the current moment shall be used as the setting current, and a "Setting current self-tuning completed" prompt message shall be given and the self-tuning shall be exited; if the load has not reached a stable operating state within the specified time range T, the self-tuning shall be exited, the default setting current of the CPS shall be used and a "Parameter self-tuning failed" prompt message shall be given; the specified time range T may be adjusted according to the power supply and load conditions on site, preferably 20 seconds; during the above parameter self-tuning process, in order to avoid accidental triggering of protection actions during the startup process and to ensure the basic safety of the load, the CPS protection functions other than short circuit protection, locked rotor protection and phase loss protection shall be temporarily disabled. During the startup process, if the load current is detected to reach the preset threshold of short circuit protection, the parameter self-tuning function shall be automatically exited and a "Parameter self-tuning failed" prompt message shall be given; the default setting current may be the default setting parameter set by the CPS factory, the setting parameter set by the user, or the parameter set in the last automatic tuning.
[0029] (5) After the setting current is self-set, the overload trip level is set; The overload tripping level can be set using various existing self-tuning methods; in this embodiment, the automatic setting method for the overload tripping level is as follows: calculate the ratio of the starting heat capacity of each overload tripping level to the reference heat capacity corresponding to that overload tripping level, and select the overload tripping level whose ratio is less than a preset threshold and closest to the preset threshold as the setting value of the current overload tripping level. The calculation of thermal capacity parameters such as starting heat capacity and reference heat capacity of motor loads under different overload tripping levels is a prior art technique. This embodiment adopts a calculation method disclosed in "Inverse Time Overload Protection Algorithm Based on Thermal Effect", as detailed below: Starting heat capacity E n It is based on the inverse-time overload protection algorithm (recursive algorithm) of the load current, which applies at regular intervals. The cumulative heat capacity of the front load, i.e., the starting heat capacity, is calculated as follows:
[0030] in, The unit of time is used to calculate the current. This is the effective value of the current; The additional heat generated per unit time is the amount of current flowing through the load. This represents the total heat generated up to the previous calculation time. This refers to the total heat generated up to the current calculation point; For different tripping levels The coefficient of residual heat after heat loss over time. <1 and is a constant coefficient; Reference heat capacity The reference heat capacity corresponding to each overload tripping level can be calculated based on the determined setting current and different overload tripping levels. This refers to the allowable heat output threshold (rated heat capacity) for the load, and its calculation formula is as follows:
[0031] In the formula, Design constant; The setting current is obtained from parameter self-tuning; The balance coefficient corresponding to each overload tripping level ; Calculate the starting heat capacity for each overload tripping level according to the formula. The reference heat capacity corresponding to this overload trip level ;
[0032] The heat capacity ratio is further calculated using the above formula. E The heat capacity ratio E The heat capacity ratio is selected by comparing it with a preset threshold. E The overload tripping level closest to but not exceeding the threshold is used as the setting value for the current overload tripping level. This completes the self-tuning of the overload tripping level. Of course, the heat capacity of the three-phase load current is calculated separately to obtain the ratio of the three-phase load current heat capacity for each overload tripping level. E The ratio of three-phase load current to heat capacity E Based on the largest phase; In this embodiment, the overload tripping level is set in the range of 10A, 10, 15, 20, 25, and 30. The calculated heat capacity ratios are shown in Table 1. Table 1
[0033] For example, if the preset threshold is set to 80%, the calculated three-phase load current heat capacity ratio values under 10 trip levels are E2 (75%, 78%, 79%), and the calculated three-phase load current heat capacity ratio values under 15 trip levels are E3 (50%, 53%, 55%), then the corresponding 10 levels are selected as the overload trip level as the setting value of the current overload trip level.
Claims
1. A self-tuning method for a control and protection switch, wherein the setting current is automatically adjusted after the control and protection switch is started and the load enters a stable operating state; characterized in that, The following method is used to determine whether the load has entered a stable operating state: the load has entered a stable operating state based on whether the fluctuation of the load current in each phase shows a downward trend; the fluctuation of the load current in any phase is the ratio of the standard deviation to the mean of the load current value of that phase after the control and protection switch is started in real time; the load current value must be within the adjustment range of the setting current parameter allowed by the control and protection switch.
2. The self-tuning method for control and protection switches as described in claim 1, characterized in that, The volatility exhibits a decreasing trend based on n consecutive fixed periods, where the continuous decreasing gradient of volatility within the n periods is ≥ ΔK.
3. The self-tuning method for control and protection switches as described in claim 1, characterized in that, The automatic setting of the setting current specifically includes the following steps: Determine whether the load has entered a stable operating state within a specified time range after the control and protection switch is started. If so, use the maximum value of the load current in each phase at the moment of entering the stable operating state as the setting current and exit self-tuning; otherwise, exit self-tuning and use the default setting current of the control and protection switch as the setting current.
4. The self-tuning method for control and protection switches as described in claim 1, characterized in that, After automatically setting the current setting, automatic setting of the overload trip level is also performed.
5. The self-tuning method for the control and protection switch as described in claim 4, characterized in that, The following method is used to automatically adjust the overload trip level: calculate the ratio of the starting heat capacity of each overload trip level to the reference heat capacity corresponding to that overload trip level, and select the overload trip level whose ratio is less than a preset threshold and closest to the preset threshold as the setting value of the current overload trip level.
6. A self-tuning device for controlling and protecting switches, characterized in that, The system includes a current setting module for automatically setting the current when the load enters a stable operating state after the control and protection switch is activated. The current setting module determines whether the load has entered a stable operating state using the following method: whether the fluctuation of the load current in each phase shows a decreasing trend; the fluctuation of the load current in any phase is the ratio of the standard deviation to the mean of the load current value in that phase after the control and protection switch is activated, calculated in real time; and the load current value must be within the adjustment range of the setting current parameters allowed by the control and protection switch.
7. The self-tuning device for controlling and protecting switches as described in claim 6, characterized in that, The volatility exhibits a decreasing trend based on n consecutive fixed periods, where the continuous decreasing gradient of volatility within the n periods is ≥ ΔK.
8. The self-tuning device for control and protection switches as described in claim 6, characterized in that, The automatic setting of the setting current specifically includes the following steps: Determine whether the load has entered a stable operating state within a specified time range after the control and protection switch is started. If so, use the maximum value of the load current in each phase at the moment of entering the stable operating state as the setting current and exit self-tuning; otherwise, exit self-tuning and use the default setting current of the control and protection switch as the setting current.
9. The self-tuning device for control and protection switches as described in claim 6, characterized in that, It also includes an overload trip level setting module, which is used to automatically set the overload trip level after automatically setting the setting current.
10. The self-tuning device for controlling and protecting switches as described in claim 9, characterized in that, The overload tripping level setting module uses the following method to automatically set the overload tripping level: calculate the ratio of the starting heat capacity of each overload tripping level to the reference heat capacity corresponding to that overload tripping level, and select the overload tripping level whose ratio is less than a preset threshold and closest to the preset threshold as the setting value of the current overload tripping level.
11. A control and protection switch, characterized in that, Includes the self-tuning device as described in any one of claims 6 to 10.