A distribution network single-phase ground fault timing alarm method and system

Abstract

The application provides a distribution network single-phase grounding fault timing alarm method, comprising the following steps: receiving a single-phase grounding fault signal, determining a fault section; obtaining power grid equipment health degree information in the fault section; obtaining allowed fault operation time of the fault section based on the power grid equipment health degree information; and issuing an alarm information according to the obtained allowed fault operation time and actual fault operation time of the fault section. The application provides a distribution network single-phase grounding fault timing alarm method and system, which re-determines the allowed fault operation time of the single-phase grounding fault section according to the equipment health degree information of the fault section, and issues an alarm information after the fault operation reaches the allowed time, so that the fault troubleshooting work can be more accurately guided, and the reliability of power grid operation is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power production safety, and particularly relates to a distribution network single-phase grounding fault timing alarm method and system. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] At present, the small current system in the distribution network system is usually a neutral point ungrounded system, because the power supply reliability is considered, when the single-phase grounding fault occurs in the small current system, the line voltage of the system is still symmetrical, and the power users can normally use electricity.

[0004] When the single-phase grounding fault occurs, it is usually stipulated that the system is allowed to operate with a fault for 1-2 hours, if the fault cannot be eliminated within the time, in order to prevent the system from operating with a fault for too long, isolation treatment is performed again. However, in actual operation, it is found that overvoltage is generated when the single-phase grounding fault occurs, and many power equipment are aged due to long-time operation, even within the 2-hour allowed fault operation time, damage to the switch cabinet, voltage transformer, lightning arrester and the like in the system may still occur. SUMMARY

[0005] Therefore, in order to overcome the shortcomings of the prior art, the present application provides a distribution network single-phase grounding fault timing alarm method and system, which re-determines the allowed fault operation time of the single-phase grounding fault, and sends an alarm information after the fault operation reaches the allowed time.

[0006] In a first aspect of the present application, a distribution network single-phase grounding fault timing alarm method is provided, comprising:

[0007] receiving a single-phase grounding fault signal, determining a fault section;

[0008] obtaining health degree information of power grid equipment in the fault section;

[0009] obtaining the allowed fault operation time of the fault section based on the health degree information of the power grid equipment;

[0010] sending an alarm information according to the obtained allowed fault operation time of the fault section and the actual fault operation time.

[0011] In a further technical solution, the obtaining of the health degree information of the power grid equipment in the fault section is specifically: determining the health degree of the equipment according to the initial health degree of the power grid equipment, the aging coefficient and the equipment operation time.

[0012] In a further technical solution, the obtaining of the allowed fault operation time of the fault section based on the health degree information of the power grid equipment comprises:

[0013] calculate the relative health degree of the power grid equipment;

[0014] perform load factor compensation on the relative health degree to calculate a compensated relative health degree;

[0015] calculate the allowed fault operation time corresponding to each power grid equipment according to the compensated relative health degree and the maximum allowed fault operation time.

[0016] Further, the method further includes: obtaining the minimum value of the allowed fault operation time corresponding to each power grid equipment as the allowed fault operation time of the fault section.

[0017] Further, the method further includes: when the actual fault operation time reaches a first threshold time, issuing a first alarm information; and when the actual fault operation time reaches a second threshold time, issuing a second alarm information.

[0018] Further, the first threshold time is the allowed fault operation time of the fault section minus a set time; and the second threshold time is the allowed fault operation time of the fault section.

[0019] In a second aspect, the application provides a single-phase grounding fault timing alarm system for distribution network, which includes:

[0020] a fault locating module configured to receive a single-phase grounding fault signal and determine a fault section;

[0021] a health degree obtaining module configured to obtain health degree information of power grid equipment in the fault section;

[0022] a calculating module configured to obtain the allowed fault operation time of the fault section based on the health degree information of the power grid equipment;

[0023] an alarming module configured to issue an alarm information according to the obtained allowed fault operation time of the fault section and an actual fault operation time.

[0024] Further, the method further includes:

[0025] calculating the relative health degree of the power grid equipment;

[0026] performing load factor compensation on the relative health degree to calculate a compensated relative health degree;

[0027] Calculate the corresponding allowable fault operation time of each power grid device based on the relative health degree after compensation and the maximum allowable fault operation time;

[0028] The minimum value of the obtained allowable operating time with faults corresponding to each power grid device is used as the allowable operating time with faults of the fault section.

[0029] According to a third aspect of the present invention, a computer-readable storage medium is provided.

[0030] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the above-mentioned method for online monitoring of power grid equipment.

[0031] A fourth aspect of the present invention provides a computer device.

[0032] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned method for online monitoring of power grid equipment when executing the program.

[0033] One or more of the above technical solutions have the following beneficial effects:

[0034] The present invention provides a distribution network single-phase grounding fault timing alarm method and system. According to the equipment health information of the fault section, the fault section of the single-phase grounding fault is re-determined to allow the fault operation time, and an alarm message is issued after the fault operation time reaches the allowed time. It can more accurately guide the fault investigation and processing work and improve the reliability of the power grid operation.

[0035] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which constitute a part of the present disclosure, are used to provide a further understanding of the present disclosure. The exemplary embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation to the present disclosure.

[0037] Figure 1 This is a flow chart of the method according to the first embodiment of the present invention. DETAILED DESCRIPTION

[0038] The present invention provides a distribution network single-phase grounding fault timing alarm method and system, which redefines the allowable fault operation time of a single-phase grounding fault and issues an alarm message after the fault operation reaches the allowable time. It can more accurately guide fault troubleshooting and improve the reliability of power grid operation.

[0039] Example 1

[0040] like Figure 1 As shown, this embodiment provides a distribution network single-phase grounding fault timing alarm method, including:

[0041] Receive single-phase ground fault signal and determine the fault section;

[0042] Obtain health information of power grid equipment within the fault section;

[0043] Obtain the allowable fault-carrying operation time of the fault section based on the health information of the power grid equipment;

[0044] An alarm message is issued based on the obtained allowable operating time with fault and actual operating time with fault of the fault section.

[0045] Single-phase grounding is the most common fault in low-current systems (10kV, 35kV, etc.). When a single-phase grounding occurs, the system's line voltage remains symmetrical, allowing power users to use electricity normally. Furthermore, the insulation level of the system's equipment takes into account the voltage conditions at the time of grounding, and the insulation can withstand it. Therefore, based on the above conditions and considering the reliability of power supply, the low-current grounding system can continue to operate when a single-phase grounding occurs.

[0046] Existing textbooks and regulations all stipulate that after a single-phase grounding fault, the fault is allowed to operate for 1 to 2 hours. However, this provision is based on years of experience and has no actual theoretical basis. In addition, this time is a fixed value and is not adjusted according to the actual situation of the distribution network. Although the time to eliminate single-phase grounding faults is gradually shortening, there are still some faults that are difficult to accurately locate and eliminate in a short period of time. At this time, 2 hours is usually still used as the time basis for power outage isolation. However, due to the different operating conditions of various power grid equipment in the distribution network and different years of operation, there are differences in the withstand voltage levels of different equipment. Since the non-grounded phase voltage increases when single-phase grounding occurs (increased to the voltage during normal operation), the voltage of the non-grounded phase increases when single-phase grounding occurs (increased to the voltage during normal operation). Times), which will cause the power grid equipment to be in an overvoltage state. Years of operating experience have shown that the overvoltage caused by single-phase grounding is an important root cause of many equipment failures in the system, often causing damage to switch cabinets, voltage transformers, and lightning arresters.

[0047] Therefore, this embodiment proposes to set a corresponding allowable overvoltage operation time according to the actual operating status of the power grid equipment.

[0048] First, receive the single-phase ground fault signal and determine the fault section. Currently, the monitoring of single-phase ground faults is very fast. After a single-phase ground fault occurs, the line voltage remains unchanged, and the phase voltage of the non-grounded phase rises to the normal operating voltage. times, so it is easy to determine the section where the fault is located, which will not be described here.

[0049] Secondly, obtain the health information of the power grid equipment in the fault section.

[0050] After determining the fault zone, we can identify all grid equipment affected by the single-phase ground fault within the fault zone. Considering the differences in age, operating status, and voltage withstand capability of different grid equipment, it is necessary to determine the overvoltage operating time (i.e., the allowable operating time with faults) based on the actual status of each device.

[0051] Specifically, this embodiment reflects the actual status of the equipment through the health information of the power grid equipment.

[0052] Health is a parameter based on the principle of equipment aging that reflects the change of equipment health level over time. The specific calculation formula is:

[0053]

[0054] Where HI is the calculated device health, HI0 represents the initial health of the power grid equipment, which is usually 0.5, B is the aging coefficient, T1 is the year corresponding to the device health of HI0, and T0 is the year to be calculated. Since this embodiment determines the device status at the time of the fault, it is only necessary to calculate the current health of the device. The above formula can be simplified to:

[0055]

[0056] Where ΔT is the equipment commissioning time.

[0057] The health value ranges from 0 to 10, with lower values ​​indicating better device health. A health value of 0 to 3 is generally considered good, while a health value of 3 to 6.5 indicates significant device aging and requires regular maintenance, with the aging rate rapidly increasing. A health value above 6.5 indicates severe device aging, with a significantly increased failure rate. A device's lifespan is generally considered to end when the health value reaches 7.

[0058] The aging coefficient of different equipment is different. It can be obtained based on the design operating life of the equipment, or it can be calculated based on the actual use of the equipment, the temperature and humidity, pollution level, dirt level of the environment in which the equipment is located, and the load level during normal operation, instead of the design operating life of the equipment.

[0059] After obtaining the equipment health, the allowable fault operation time of the fault section is obtained based on the power grid equipment health information.

[0060] Specifically, after obtaining the equipment health, in order to facilitate subsequent calculations, the health is normalized and the relative health of the power grid equipment is calculated.

[0061] Since it is generally believed that the device lifespan ends when the health reaches 7, the health value is normalized here not to a range of 0 to 10, but rather to a range of 0 to 7. Furthermore, since a higher health value indicates worse health, to facilitate subsequent time calculations, it is converted to a relative health value, where a higher relative health value indicates better health.

[0062] Relative health The calculation formula is:

[0063]

[0064] Among them, HI max is the maximum health value that can be obtained, here it is 7, HI min is the minimum health value that can be obtained, which is 0 here.

[0065] During normal operation, the load on the equipment directly determines its health. In the case of single-phase grounding, the equipment is actually operating in an overvoltage state, where the operating voltage often exceeds its rated voltage. When selecting power grid equipment, taking voltage transformers as an example, reliability and cost-effectiveness must be considered comprehensively. Therefore, the load factor during normal operation is generally controlled between 40% and 60%. According to GB / T 20840.3-2013, the rated voltage factor of voltage transformers used in systems with non-effective neutral grounding is 1.2 during continuous operation. In the event of an overvoltage, they can operate at a rated voltage factor of 1.9 for up to 8 hours. However, after years of continuous operation, equipment reliability deteriorates due to aging. Therefore, a load factor, f, is introduced to compensate for the relative health. Table 1 lists the load factor values ​​for equipment under different load conditions.

[0066] Table 1 Power grid equipment load factor table

[0067]

[0068] The calculation formula of relative health HI2 after compensation is:

[0069]

[0070] The relative health after compensation reflects the device's own status and current operating status. Using the relative health after compensation as a coefficient, the corresponding allowable fault operation time T of each power grid device is calculated:

[0071]

[0072] Where T0 represents the maximum allowable operating time with faults. In actual calculations, the commonly used allowable operating time with faults of 2 hours (120 minutes) can be used as T0.

[0073] After obtaining the allowable fault operation time T corresponding to each power grid equipment, the minimum value, that is, the allowable fault operation time of the equipment with the lowest voltage resistance, should be used as the allowable fault operation time of the fault section, so as to ensure the stable operation of all equipment in the section and minimize the impact of fault operation.

[0074] After the allowable running time with fault of the fault section is obtained, an alarm message is issued according to the obtained allowable running time with fault and the actual running time with fault of the fault section.

[0075] Considering the actual conditions of on-site troubleshooting and repair, and to give maintenance personnel ample preparation time, a dual alarm can be set. The first threshold is the faulty section's allowable operating time with faults minus a set time (e.g., 10 minutes), and the second threshold is the faulty section's allowable operating time with faults. When the actual operating time with faults reaches the first threshold, the first alarm is issued, reminding on-site maintenance personnel that the allowable operating time with faults is approaching and that they should promptly repair or isolate the faulty section and temporarily power off important users. When the actual operating time with faults reaches the second threshold, the second alarm is issued, prompting them to quickly isolate the faulty section to avoid insulation hazards caused by prolonged overvoltage operation.

[0076] The above method is further explained below with reference to specific data.

[0077] Assume that a single-phase grounding fault occurs in a 10kV system. Based on the operating data of each distribution network node received by the command center, it is determined that the single-phase grounding fault occurs in section X.

[0078] Section X contains four power grid equipment: voltage transformers A and B, lightning arrester C, and switchgear D. Based on a comprehensive evaluation of the equipment's years of operation, design life, environment, and operating status, the aging coefficients of the four equipment are 0.088, 0.086, 0.132, and 0.106, respectively.

[0079] The four devices have been in operation for 16 years. According to the health calculation formula, the initial health HI0 is taken as 0.5, and the health of the four devices are 2.04, 1.98, 4.13, and 2.73, respectively. The relative health is 0.708, 0.717, 0.410, and 0.611, respectively.

[0080] Assuming that the load rate of the four devices is 60% during normal operation, when a single-phase ground fault occurs, the actual load rate is Therefore, the load factor f=1.6 is taken, and the relative health of the four devices after compensation are: 0.443, 0.448, 0.256, and 0.382 respectively.

[0081] Take the maximum allowable fault running time The calculated allowable fault operation times of the four devices are: 0.885, 0.897, 0.512, 0.763 (unit: hour), which are converted into minutes: 53 minutes, 54 minutes, 31 minutes, 46 minutes (accurate to the integer).

[0082] Therefore, the allowable fault-carrying operation time of the fault section takes the minimum value of 31 minutes.

[0083] If the set time is 10 minutes, the first threshold time is 21 minutes and the second threshold time is 31 minutes. After the system has been running with a fault for 21 minutes, the first alarm message will be sent to the on-site command center, indicating that there are still 10 minutes left before the maximum allowable running time with a fault, and the maintenance progress needs to be accelerated. If the fault cannot be completed within 10 minutes, it is necessary to report to the control center and make preparations for power outage isolation, temporary power outage reminders for important users, or switching of backup lines.

[0084] After 31 minutes of operation with a fault, a second alarm message is sent to the on-site command center to remind that the maximum allowable operation time with a fault has been reached. To ensure the safety of the equipment, the power should be cut off as soon as possible.

[0085] According to statistics, there were 13 single-phase grounding faults in Jining in the fourth quarter of 2021, with an average handling time of 28 minutes. This average handling time is still relatively long. Therefore, for sections with aging equipment, excessive handling times may pose a safety hazard. The method proposed in this embodiment can provide guidance on fault handling time, urge improvements in the handling efficiency of single-phase grounding faults, and enhance the safety and reliability of power grid operations.

[0086] Example 2

[0087] This embodiment provides a distribution network single-phase grounding fault timing alarm system, including:

[0088] a fault location module configured to receive a single-phase ground fault signal and determine a fault section;

[0089] A health acquisition module is configured to acquire health information of power grid equipment within a fault section;

[0090] A calculation module is configured to obtain an allowable fault-carrying operation time of a fault section based on the health information of the power grid equipment;

[0091] The alarm module is configured to issue an alarm message according to the obtained allowable operating time with fault and actual operating time with fault of the fault section.

[0092] The allowable fault-carrying operation time of the fault section is determined based on the health information of the power grid equipment, including:

[0093] Calculate the relative health of grid equipment;

[0094] Perform load factor compensation on the relative health and calculate the relative health after compensation;

[0095] Calculate the corresponding allowable fault operation time of each power grid device based on the relative health degree after compensation and the maximum allowable fault operation time;

[0096] The minimum value of the obtained allowable operating time with faults corresponding to each power grid device is used as the allowable operating time with faults of the fault section.

[0097] It should be noted here that the various modules of the system in this embodiment correspond one-to-one to the various steps of the method in Example 1, and the specific implementation processes are the same, which will not be repeated here.

[0098] Example 3

[0099] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the steps in the above-mentioned method for timing alarm of single-phase grounding fault in a distribution network are implemented.

[0100] Example 4

[0101] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the steps in the above-mentioned method for timing alarm of single-phase grounding fault in a distribution network are implemented.

[0102] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage and optical storage, etc.) containing computer-usable program code.

[0103] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A timing alarm method for single-phase grounding fault in a distribution network, characterized in that: include: Receive single-phase ground fault signal and determine the fault section; Obtain the health information of the power grid equipment in the fault section. Specifically, determine the health of the equipment based on the initial health of the power grid equipment, the aging coefficient, and the equipment commissioning time. The specific calculation formula is: Where HI is the calculated equipment health, HI0 represents the initial health of the power grid equipment, B is the aging coefficient, and ΔT is the equipment commissioning time; Based on the health information of power grid equipment, the allowable fault operation time of the fault section is obtained, including: Calculate the relative health of power grid equipment using the following formula: Among them, HI1 is relative health, HI max is the maximum health value that can be obtained, HI min is the minimum health value that can be obtained; The relative health is compensated for the load factor and the relative health after compensation is calculated using the following formula: Among them, HI2 is the relative health after compensation, and f is the load factor; According to the relative health degree after compensation and the maximum allowable fault operation time, the allowable fault operation time corresponding to each power grid device is calculated. The calculation formula is: Where, T is the allowable fault operation time corresponding to each power grid equipment, and T0 represents the maximum allowable fault operation time; An alarm message is issued based on the obtained allowable operating time with fault and actual operating time with fault of the fault section.

2. A distribution network single-phase grounding fault timing alarm method according to claim 1, characterized in that: The method of determining the allowable operation time with faults based on the health information of the power grid equipment further includes: using the minimum value of the obtained allowable operation time with faults corresponding to each power grid equipment as the allowable operation time with faults of the fault section.

3. A distribution network single-phase grounding fault timing alarm method according to claim 1, characterized in that: The issuing of alarm information based on the obtained allowable running-with-fault time and actual running-with-fault time includes: issuing a first alarm information when the actual running-with-fault time reaches a first threshold time; issuing a second alarm information when the actual running-with-fault time reaches a second threshold time.

4. A distribution network single-phase grounding fault timing alarm method according to claim 3, characterized in that: The first threshold time is the allowable operating time with fault of the fault section minus the set time; the second threshold time is the allowable operating time with fault of the fault section.

5. A distribution network single-phase grounding fault timing alarm system, characterized in that: include: a fault location module configured to receive a single-phase ground fault signal and determine a fault section; The health acquisition module is configured to obtain the health information of the power grid equipment in the fault section. Specifically, the health of the equipment is determined based on the initial health of the power grid equipment, the aging coefficient, and the equipment commissioning time. The specific calculation formula is: Where HI is the calculated equipment health, HI0 represents the initial health of the power grid equipment, B is the aging coefficient, and ΔT is the equipment commissioning time; The calculation module is configured to obtain the allowable fault operation time of the fault section based on the health information of the power grid equipment, including: Calculate the relative health of power grid equipment using the following formula: Among them, HI1 is relative health, HI max is the maximum health value that can be obtained, HI min is the minimum health value that can be obtained; The relative health is compensated for the load factor and the relative health after compensation is calculated using the following formula: Among them, HI2 is the relative health after compensation, and f is the load factor; According to the relative health degree after compensation and the maximum allowable fault operation time, the allowable fault operation time corresponding to each power grid device is calculated. The calculation formula is: Where, T is the allowable fault operation time corresponding to each power grid equipment, and T0 represents the maximum allowable fault operation time; The alarm module is configured to issue an alarm message according to the obtained allowable operating time with fault and actual operating time with fault of the fault section.

6. A distribution network single-phase grounding fault timing alarm system as claimed in claim 5, characterized in that: The method of determining the allowable fault-carrying operation time of the fault section based on the health information of the power grid equipment includes: Calculate the relative health of grid equipment; Perform load factor compensation on the relative health and calculate the relative health after compensation; Calculate the corresponding allowable fault operation time of each power grid device based on the relative health degree after compensation and the maximum allowable fault operation time; The minimum value of the obtained allowable operating time with faults corresponding to each power grid device is used as the allowable operating time with faults of the fault section.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the distribution network single-phase grounding fault timing alarm method according to any one of claims 1 to 4 are implemented.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the steps of the distribution network single-phase grounding fault timing alarm method according to any one of claims 1 to 4 are implemented.

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