Abstract: At present, 10kV distribution lines are long, the load is scattered, the number of equipment is large, the operation and maintenance conditions are poor, the protection measures are few.
In the operation, not only the mechanical and electrical load, but also suffer from various weather factors, so the probability of failure is greater.
The following is based on the fault analysis of distribution operation in recent years, trying to find out some objective laws of distribution line fault, in order to prevent the loss caused by distribution line fault.
Key words: transformer 10KV line fault causes prevention measures
In the past two years, with the transformation of the urban network, part of the overhead lines in the downtown area were replaced by ground cables.
According to all kinds of faults occurring in daily operation, the regularity of line accidents is summarized and targeted measures are taken to prevent or eliminate them, so as to minimize the power failure area and shorten the power failure time to ensure the safe and reliable power supply and operation of the 10KV distribution network.
At the same time, it plays a reference role in the planning and design of the future 10kV line.
Common faults of distribution lines
1.1 Distribution line fault.
General line fault, from the nature of the three forms of single-phase grounding, phase-to-phase short circuit, grounding phase-to-phase short circuit.
However, according to the protection function of the power grid, it will only trip when the phase-to-phase short circuit fault is caused. The grounding fault does not trip, but can only send the grounding signal. The 10kV system can resist single-phase grounding for 2 hours, and the insulation of the other two phases will be damaged after a long time.
1.2 Single-phase ground fault.
This kind of fault is difficult to find, because it is not enough to cause tripping, assuming that there is a problem on the user side, the fall-off fuse does not fall, there is no obvious distinguishing mark.
But ground faults are easier to find when they are live at night, because lighting is easier to spot during patrols than during the day.
1.3 Phase short circuit fault.
Interphase short circuit caused by foreign bodies.
In the lines near streets and garbage recycling stations, light materials of conductors and semiconductors may be scraped onto the lines due to strong winds, such as plastic paper with aluminum foil, linoleum paper with aluminum foil, TV antennas cut off near the lines, branches cut off, and discarded recording tape, etc., which may cause alternating faults of the lines.
(2) external damage, the client due to various faults caused by phase short circuit.
User low voltage line-to-line fault caused by equipment, transformer burn out, vehicle bump broken pole, super car downed wires, etc., these faults generally the initiative to contact with me by the user, you can more easily grasp the fault location, even if no calls, check line is easy to find, the commonly occurred in the construction site, such as boulevard is a busy public places.
3. Alternate short circuit caused by bird damage.
General birds such as magpie, the eagle wings distance amounting to more than 40 cm and link dense it is a good place for bird nest, once the bird fall on the cross arm, the whereabouts or takeoff wings, and it is easy to cause short circuit, nesting branch length is differ, but generally in more than 40 cm, often cause tripping.
Such incidents occur on a wide scale and in areas with few people and many trees, making maintenance work heavy and ineffective, and sometimes seeing birds approaching the point of failure.
And should be installed on the line to prevent bird thorn and bird drive, but also because of the distribution line points, wide cost, no operability.
Lightning caused by the phase short circuit.
When it comes to lightning strikes, generally occur in the rural network, urban distribution lines because of the surrounding high-rise buildings, become the main lightning current trigger point (because high-rise buildings have more than lightning rods and lightning protection facilities), so the urban distribution lines are basically not affected by lightning strikes.
However, the agricultural network lines spread all over the fields, hills and slopes, and became the highest point around the whole area. Once lightning strikes occurred, it became the lightning current channel.
2. Preventive measures to be taken
2.1 Strengthen operation management
From the perspective of operation, operators should inspect equipment on time according to the requirements of operation regulations, provide equipment defects in a timely and accurate manner, provide basis for maintenance and test, find hidden trouble in time, and repair in time, so as to reduce the line failure rate.
To this end, operating personnel should be "three familiar with three can", from "strict", "diligent", "fine", "familiar" up and down.
Strict: that is to establish a strict equipment regular inspection system, and resolutely implement;
Diligence: that is, work actively, no leakage, pay more attention to the high failure rate of the line equipment operating conditions;
Detail: namely careful inspection, careful analysis, timely detection and reporting of defects;
Familiarity: that is, not only familiar with the equipment, but also familiar with its performance, parameters, structure, geographical environment, climate factors, etc., so as to have a good idea.
2.2 Strengthen the line to prevent damage by external forces
Distribution circuit external force damage phenomenon is very serious, high and low voltage lines DaoGe serious illegal construction, rural construction, yamada bulldozing of levelling, root soil, people to break the insulator, throw the wire guide line, power line fault, such as theft, to caused great harm to the safe operation of power distribution lines.
Measures taken:
(1) To hang warning signs on line poles and towers, write propaganda slogans, etc., to educate children, etc. It is forbidden to climb electric poles and towers, break line insulators, throw iron wires on wires, or fly kites near the lines, etc., with a focus on strengthening the prevention work of external damage or serious theft areas.
(2) Organize the manpower and material resources of relevant units to carry out the publicity work of "Electric Power Law" and "Regulations on the Protection of Electric Power Facilities" along the electric power line.
And as far as possible with schools, administrative villages to get in touch, to jointly carry out a planned and organized dissemination of leaflets, posters, paint slogans, etc., to carry out a variety of forms of publicity activities, education and care for electric power facilities.
(3) for the construction of illegal buildings from the beginning of the interpretation, dissuasion.
And issued the "power illegal construction accident hidden danger notice" to the illegal construction, clear the responsibility of both parties.
(4) On the basis of publicity and education, through the public security law enforcement system to increase the illegal construction, external damage, especially burglars to crack down.
For the serious illegal buildings that cause safe power supply, the public security bureau and relevant administrative units shall forcibly remove the buildings, and solve the obstacle removal work in the line corridor year by year.
If the theft of electric power facilities causes relatively serious property losses or causes major accidents, the theft shall be investigated and investigated through the public security system to deter and crack down on the thieves.
Get in touch with the urban construction department and the Yamada construction department, cooperate with the planning, design, construction and other work in safety production, and do not leave any hidden danger of power accidents.
2.3 Attach importance to technological progress and improve the technical level of distribution equipment
(1) Improve the level of power network equipment, actively adopt new technology, new equipment, such as vacuum circuit breaker, SF6 circuit breaker, vacuum switch on the column, metal oxide lightning arrester, silicone rubber insulator, crosslinked cable, etc., reduce the equipment quality problems, short test cycle caused by unnecessary power failure.
(2) According to the situation of urban power grid protection configuration and operation experience, it is suggested that comprehensive microcomputer protection with protection configuration should be adopted in the new substation.
On the basis of current velocity break, over current break and reclose, microcomputer protection should also have the functions of low voltage (or compound pressure) lock, time limit speed break and so on, in order to adapt to the different requirements of line and load change to the protection mode.
(3) Relying on scientific and technological progress to gradually achieve the state monitoring and maintenance of transmission, transformation and distribution equipment, through online testing, salt density guidance cleaning, live temperature measurement, oil supervision and other advanced testing methods and scientific analysis and evaluation methods, master the performance of equipment, guide the maintenance of equipment;
The transformer is coated with RTV to extend the cleaning cycle.
(4) Rely on scientific and technological progress, actively carry out live work.
Set up electrified working class, equipped with corresponding electrified working vehicles and electrified working tools.
Under the premise of conforming to safety conditions, can implement live work, as far as possible to implement live work, such as live break fire connection, deal with defects, etc., in order to effectively reduce the line blackout time.
2.4 Strengthen the line reconstruction
To fundamentally solve the problem, it is necessary to invest in line transformation: several lines with serious trip should be included in the plan as soon as possible, and funds should be allocated to complete line transformation, so that the equipment can meet the requirements of safe operation;
If no section switch is installed on the circuit, plans and funds shall be listed and completed step by step.
The cause of distribution line fault is complex, the line fault rate is high, the prevention of distribution line fault is a long-term, difficult task, should be constantly summarized through theory and practice, development, and constantly improve.
Focused in this paper from the internal cause and external cause of distribution line fault caused carries on the analysis and summary, tripping condition of different months and higher rates of tripping circuit, classification, this paper analyses, puts forward the line failure rate mutations caused by climate change, which demonstrates the overall distribution circuit of resistance are less able to natural disasters.
There are not only design factors, but also the construction process problems, and the operation management problems.
On this basis, the paper discusses how to prevent and reduce the failure rate of distribution lines by strengthening the operation management, strengthening the prevention of external damage, strengthening the maintenance and elimination of defects, increasing the investment and other measures.