Grounding line selection adaptive return coefficient method
By calculating the adaptive return coefficient limit curve variable and combining it with the set return coefficient, the action return value of the low-current grounding power system is adjusted, which solves the problem of return coefficient mismatch in the low-current grounding system and realizes the accurate calculation of the action return value.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUIZHOU POWER GRID CO LTD
- Filing Date
- 2025-12-19
- Publication Date
- 2026-05-12
AI Technical Summary
In low-current grounding power systems, the fixed action return coefficient cannot meet the requirements of high-resistance single-phase grounding faults and load scenarios, resulting in problems such as low return coefficient leading to failure to return or high return coefficient leading to premature return.
By acquiring the three-phase current of the system, calculating the minimum set value and preset threshold of the phase current mutation, determining the adaptive return coefficient limit curve variable, and combining the set return coefficient, calculating the action return value, the adaptive adjustment of the return coefficient is realized.
This solves the problem of the return coefficient not matching after a single-phase ground fault disappears, or the problem of premature return due to the return coefficient not matching before the fault disappears, and achieves accurate calculation of the action return value.
Smart Images
Figure CN122017448A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of grounding line selection technology, and in particular to an adaptive return coefficient method for grounding line selection. Background Technology
[0002] Single-phase grounding faults in low-current grounding power systems are highly varied, often with grounding currents ranging from tens of milliamperes to nearly a thousand amperes. The fixed operating return coefficients within these systems often fail to meet actual requirements. For example, setting a small operating value for a high-resistance single-phase grounding fault or a load results in a low return coefficient, preventing the fault from returning; conversely, setting a large operating value for a high-resistance single-phase grounding fault or a load results in a high return coefficient, causing premature return. The return coefficient is the ratio of the operating return value to the operating setting value. Therefore, an adaptive return coefficient method for low-current grounding fault selection is needed. Summary of the Invention
[0003] Therefore, the technical problem to be solved by this invention is: the need for an adaptive return coefficient method for low-current grounding line selection.
[0004] The above-mentioned technical problems are solved by the following technical solution: This invention proposes a grounding line selection adaptive return coefficient method, which includes, when a single-phase grounding fault occurs in a low-current grounding power system, obtaining the three-phase currents of the system, and calculating the minimum setpoint of the phase current mutation based on the three-phase currents. ; Obtain the pre-set tuning return coefficient and the first threshold of phase current mutation Second threshold for phase current mutation and the third threshold of phase current mutation ,in ; Calculate the adaptive return coefficient limit curve variable Minimize the phase current mutation value. The third threshold of the phase current abrupt change Compare and determine the return coefficient for practical application. Based on the return coefficient of the actual application. Calculate the action return value based on the set action value.
[0005] In a preferred embodiment of the adaptive return coefficient method for grounding line selection described in this invention: based on the minimum set value of the phase current mutation amount... and the first threshold Second threshold Third threshold Calculate the adaptive return coefficient limit curve variable Combined with the adaptive return coefficient limit curve variable With the set return coefficient The magnitude relationship determines the return coefficient for practical applications. .
[0006] In a preferred embodiment of the adaptive return coefficient method for grounding line selection described in this invention: the step of determining the return coefficient for practical application... The steps include: when the phase current sudden change is at its minimum set value Less than or equal to the third threshold of the phase current change When; if the adaptive return coefficient limit curve variable Less than or equal to the set return coefficient Then determine the return coefficient for practical application. For the tuning return coefficient If the adaptive return coefficient limit curve variable Greater than the set return coefficient Then determine the return coefficient for practical application. For the adaptive return coefficient limit curve variable .
[0007] The return coefficient is defined as the ratio of the action return value to the action set value.
[0008] In a preferred embodiment of the adaptive return coefficient method for grounding line selection described in this invention: the step of determining the return coefficient for practical application... The steps also include: when the phase current sudden change is at its minimum set value Greater than the third threshold of the phase current change When; if the adaptive return coefficient limit curve variable Greater than or equal to the tuning return coefficient Then determine the return coefficient for practical application. For the tuning return coefficient If the adaptive return coefficient limit curve variable Less than the set return coefficient Then determine the return coefficient for practical application. For the adaptive return coefficient limit curve variable .
[0009] In a preferred embodiment of the adaptive return coefficient method for grounding line selection described in this invention: the formula for calculating the action return value is: .
[0010] In a preferred embodiment of the adaptive return coefficient method for grounding line selection described in this invention: the minimum set value of the phase current mutation is: The acquisition steps include: acquiring the three-phase currents according to a preset period; calculating the phase current mutations of the three-phase currents in real time; and selecting the minimum value among the three-phase current mutations as the minimum setpoint of the phase current mutation. .
[0011] In a preferred embodiment of the adaptive return coefficient method for grounding selection described in this invention: the variable of the adaptive return coefficient limit curve is denoted as y, the minimum fixed value of the phase current mutation is denoted as x, y and x have a preset correspondence, and the correspondence is characterized by the limit curve.
[0012] In a preferred embodiment of the adaptive return coefficient method for grounding line selection described in this invention: the adaptive return coefficient limit curve variable Based on the minimum constant value of the phase current change The first threshold of the phase current change Second threshold Third threshold The piecewise functional relationship or linear interpolation relationship is calculated.
[0013] In a preferred embodiment of the adaptive return coefficient method for grounding line selection described in this invention: the sudden change in phase current is calculated by the difference between the real-time sampled value of the three-phase phase current and the reference value before the fault.
[0014] The beneficial effects of this invention are as follows: the return coefficient k´ for actual application is obtained, and the action return value is calculated from it. That is, the action return value is equal to the set action value multiplied by the actual application return coefficient, which solves the problem that the return coefficient does not correspond after the single-phase ground fault disappears and therefore cannot return, or the return coefficient does not correspond before the single-phase ground fault disappears and therefore returns prematurely. Attached Figure Description
[0015] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention. Wherein: Figure 1 A flowchart of the present invention is shown. Detailed Implementation
[0016] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.
[0017] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terminology used in this specification should not be construed as simple names, but rather based on the meaning of the terms and the overall description of the invention.
[0018] See Figure 1 This embodiment provides a grounding line selection adaptive return coefficient method, including: when a single-phase grounding fault occurs in a low-current grounding power system, obtaining the three-phase currents of the system, and calculating the minimum setpoint for the phase current mutation based on the three-phase currents. ; Obtain the pre-set tuning return coefficient and the first threshold of phase current mutation Second threshold for phase current mutation and the third threshold of phase current mutation ,in ; Calculate the adaptive return coefficient limit curve variable Minimize the phase current mutation value. Third threshold of phase current change Compare and determine the return coefficient for practical application. Based on the return coefficient of the actual application Calculate the action return value based on the set action value.
[0019] Based on the minimum set value of phase current sudden change and the first threshold Second threshold Third threshold Calculate the adaptive return coefficient limit curve variable Combined with adaptive return coefficient limit curve variables With the set return coefficient The magnitude relationship determines the return coefficient for practical applications. .
[0020] Determine the return coefficient for practical applications The steps include: when the phase current change is at its minimum set value Less than or equal to the third threshold of phase current change When; if the adaptive return coefficient limit curve variable Less than or equal to the set return coefficient Then determine the return coefficient for practical application. To set the return coefficient If the adaptive return coefficient limit curve variable Greater than the set return coefficient Then determine the return coefficient for practical application. To adaptively return coefficient limit curve variables .
[0021] The return coefficient is defined as the ratio of the action return value to the action set value.
[0022] Determine the return coefficient for practical applications The steps also include: when the phase current change is at its minimum set value Greater than the third threshold of phase current change When; if the adaptive return coefficient limit curve variable Greater than or equal to the set return coefficient Then determine the return coefficient for practical application. To set the return coefficient If the adaptive return coefficient limit curve variable Less than the set return coefficient Then determine the return coefficient for practical application. To adaptively return coefficient limit curve variables .
[0023] The formula for calculating the action return value is: .
[0024] Minimum set value of phase current change The acquisition steps include: acquiring the three-phase currents according to a preset cycle; calculating the phase current mutation in the three-phase currents in real time; and selecting the minimum value among the three-phase current mutations as the minimum setpoint for the phase current mutation. .
[0025] The adaptive return coefficient limit curve variable is denoted as y, and the minimum set value of the phase current mutation is denoted as x. There is a preset correspondence between y and x, and this correspondence is represented by the limit curve.
[0026] Adaptive return coefficient limit curve variable Based on the minimum set value of phase current change First threshold of phase current change Second threshold Third threshold The piecewise functional relationship or linear interpolation relationship is calculated.
[0027] The sudden change in phase current is calculated by the difference between the real-time sampled value of the three-phase phase current and the reference value before the fault.
[0028] When a single-phase grounding fault occurs in a low-current grounding power system, the three-phase current is acquired according to a preset cycle, and the phase current mutation is calculated in real time using the three-phase current. The adaptive return coefficient is selected from the minimum set value of the phase current mutation. Set the set return coefficient, the first threshold value x1 for phase current sudden change, the second threshold value x2 for phase current sudden change, and the third threshold value x3 for phase current sudden change, and satisfy the following conditions: The minimum set value of the phase current mutation is compared with the preset phase current mutation threshold, and the adaptive return coefficient limit curve variable is calculated. When the minimum set value of the phase current change is less than or equal to the third threshold of the phase current change, if the calculated value of the adaptive return coefficient limit curve variable is less than or equal to the set return coefficient, then the actual applied return coefficient is the set return coefficient; if the calculated value of the adaptive return coefficient limit curve variable is higher than the set return coefficient, then the actual applied return coefficient is the adaptive return coefficient limit curve variable. When the minimum set value of the phase current change is greater than the third threshold of the phase current change, if the calculated adaptive return coefficient limit curve variable is greater than or equal to the set return coefficient, then the actual applied return coefficient is the set return coefficient; if the calculated adaptive return coefficient limit curve variable is less than the set return coefficient, then the actual applied return coefficient is the adaptive return coefficient limit curve variable.
[0029] Furthermore, the relationship between the adaptive return coefficient limit curve variable and the minimum setpoint of the phase current mutation is as follows: Where y is the adaptive return coefficient limit curve variable, x is the minimum setpoint for phase current mutation, x1 is the first threshold for phase current mutation, x2 is the second threshold for phase current mutation, and x3 is the third threshold for phase current mutation, and satisfies the following conditions: .
[0030] When the minimum setpoint x for the phase current surge is less than or equal to the third threshold x3 for the phase current surge, if the calculated value of the adaptive return coefficient limit curve variable y is less than or equal to the tuned return coefficient k, then the actual applied return coefficient... The return coefficient k is the value that is tuned, i.e. If the calculated adaptive return coefficient limit curve variable y value is higher than the tuned return coefficient k, then the actual applied return coefficient... To adaptively return the coefficient limit curve variable y, i.e. .
[0031] When the minimum setpoint x for the phase current surge is greater than the third threshold x3 for the phase current surge, if the calculated adaptive return coefficient limit curve variable y is greater than or equal to the tuned return coefficient k, then the actual applied return coefficient... The return coefficient k is the value that is tuned, i.e. If the calculated adaptive return coefficient limit curve variable y is less than the tuned return coefficient k, then the actual applied return coefficient... To adaptively return the coefficient limit curve variable y, i.e. .
[0032] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.
Claims
1. A grounding line selection adaptive return coefficient method, characterized in that: This includes acquiring the three-phase currents of a low-current grounding power system when a single-phase grounding fault occurs, and calculating the minimum setpoint for the phase current surge based on the three-phase currents. ; Obtain the pre-set tuning return coefficient and the first threshold of phase current mutation Second threshold for phase current mutation and the third threshold of phase current mutation ,in ; Calculate the adaptive return coefficient limit curve variable ; Minimize the phase current mutation value The third threshold of the phase current abrupt change Compare and determine the return coefficient for practical application. ; Based on the return coefficient of the actual application Calculate the action return value based on the set action value.
2. The adaptive return coefficient method for grounding line selection according to claim 1, characterized in that: Based on the minimum fixed value of the phase current abrupt change and the first threshold Second threshold Third threshold Calculate the adaptive return coefficient limit curve variable Combined with the adaptive return coefficient limit curve variable With the set return coefficient The magnitude relationship determines the return coefficient for practical applications. .
3. The adaptive return coefficient method for grounding line selection according to claim 2, characterized in that: The return coefficient for determining practical applications The steps include: when the phase current sudden change is at its minimum set value Less than or equal to the third threshold of the phase current change When; if the adaptive return coefficient limit curve variable Less than or equal to the set return coefficient Then determine the return coefficient for practical application. For the tuning return coefficient If the adaptive return coefficient limit curve variable Greater than the set return coefficient Then determine the return coefficient for practical application. For the adaptive return coefficient limit curve variable .
4. The adaptive return coefficient method for grounding line selection according to claim 3, characterized in that: The return coefficient is defined as the ratio of the action return value to the action set value.
5. The adaptive return coefficient method for grounding line selection according to claim 4, characterized in that: The return coefficient for determining practical applications The steps also include: when the phase current sudden change is at its minimum set value Greater than the third threshold of the phase current change When; if the adaptive return coefficient limit curve variable Greater than or equal to the set return coefficient Then determine the return coefficient for practical application. For the tuning return coefficient If the adaptive return coefficient limit curve variable Less than the set return coefficient Then determine the return coefficient for practical application. For the adaptive return coefficient limit curve variable .
6. The adaptive return coefficient method for grounding line selection according to claim 5, characterized in that: The formula for calculating the return value of the action is: .
7. The adaptive return coefficient method for grounding line selection according to claim 6, characterized in that: The minimum constant value of the phase current change The acquisition steps include: acquiring the three-phase currents according to a preset period; calculating the phase current mutations of the three-phase currents in real time; and selecting the minimum value among the three-phase current mutations as the minimum setpoint of the phase current mutation. .
8. The adaptive return coefficient method for grounding line selection according to claim 7, characterized in that: The adaptive return coefficient limit curve variable is denoted as y, and the minimum fixed value of the phase current mutation is denoted as x. There is a preset correspondence between y and x, and this correspondence is represented by the limit curve.
9. The adaptive return coefficient method for grounding line selection according to claim 8, characterized in that: The adaptive return coefficient limit curve variable Based on the minimum constant value of the phase current change The first threshold of the phase current change Second threshold Third threshold The piecewise function relationship or linear interpolation relationship is calculated.
10. The adaptive return coefficient method for grounding line selection according to claim 9, characterized in that: The sudden change in phase current is calculated by the difference between the real-time sampled value of the three-phase phase current and the reference value before the fault.