Author: Unknown
Abstract: Live working has always been the most important task of running the grid repair work of power companies, which reflects the high-tech nature of modern power grid maintenance equipment operation.For the ± 800 kV HVDC transmission line, because of its tower structure, Insulator string assembled form, the window size, number of wires and the like on split design level, safety, and technical operations and other industrial equipment using ordinary EHV differences in transmission lines, so the article on the combination of its characteristics, analyzes the calculation of UHV level test, process design live working, tools and instruments of production, and related security technical points.
Keywords: charging operations; HVDC transmission line; industrial equipment; design; test; Security
CLC: TM726.1 Document code: A Article ID: 1006-8937 (2016) 26-0112-02
Such as ± 800 kV DC transmission line UHV charging operation must be done SCIENCES embodiment security, a reasonable and effective fit for UHV insulating structural features and the technical parameters of the transmission line, is given strict security policy, and in operation productions processes and tools and instruments to achieve a reasonable.
Voltage level trial calculations 1 ± 800 kV HVDC transmission lines passing
UHV ± 800 kV DC transmission project upwardly before charging operations need to be over-voltage level simulation, preliminary design parameters to be implemented in the local demonstration project trial calculations.First line voltage levels up through simulation, in the form of this calculation, an overvoltage phenomenon is mainly due to line failure fault, the main DC bipolar bipolar operation occurs with cross-lines present in the rated load operation, metal outlet side of the inverter circuit during a ground fault is caused by.
Wherein the maximum short-circuit fault overvoltage fault operation of the line are generally bipolar dc midpoint.The different fault situations, the line occurring at different locations over different voltage amplitude range, typically in the line of maximum overvoltage embodied only in the vicinity of the point of about 200 km length position wherein its maximum overvoltage multiple ships to achieve 1.About 95 pu, as compared therewith, in the general location to ensure that a maximum voltage value in.65 pu or less.
In the form of simulation, because the discharge arc between the grounding resistance and the resistance of the channel ignoring the extreme phenomenon, therefore, reasonable to calculate the present value of the overvoltage during avoid excessive deviations do not appear to.
Consider a discharge voltage test in the form of a charged-up wire working gap.During charging work, because the discharge gap voltage analog generated during the test subject is typically a potential UHV current lines formed in the charging operation, other forms of ground potential.Such as the operating gap, gap, etc. in combination, in the job process to the process in accordance with the test voltage to determine the number of effective length of the insulating sheet Insulator work appliance, the discharge voltage curve is obtained under the test job insulating gap.
Further, altitude can also use the distance between the discharge voltage and the transmission line are calculated, and the curve describes the relationship between them is formed, during the insulation effect can be produced according to the charging operation and associated with charging principles insulation effect job optimization.During the calculation of the risk for such generated during charging, if charging operation in hazardous rate of 10-5 or less, during the upward ± 800 kV HVDC mode of operation will be maintained at a certain level of insulation disposed.
If powered operation 1 000 m or more hypotube region, not only to ensure a small gap is formed during operation between the live, but also to ensure the minimum length of a combination of a small insulating gap tool.
Further, the use of live working up line theory insulation coordination check, so the charged insulating job will fit portion ample safety margin, it is possible to ensure safety throughout the live working embodiment.
2 Live working process design and production of industrial equipment
Live working in process design and manufacture of industrial equipment is very complex diversity, in which the paper describes two live working methods and their industrial equipment design process.
2.The basic method of working in the charging line to a potential job design
± 800 kV HVDC transmission line during the design of the structure, wherein the tower with an air gap horizontal window size is important.
With conventional live working UHV comparison, it can not cross arm hanging vertical ladder and the like into the defects formed during the potential during actual operation, but by using a linear column with pulleys trajectory method and the basket is formed, which can be charged to ensure operation and smoothly enter the linear equipotential hard turret.
Before implementing charging operations, the art also autonomous special tool, for example in high-strength insulation based tools arc extinguishing device, which is entered by the equipotential basket trajectory method, an electrical potential into the column select reasonable distance, by means of the potential track control rope pulleys basket is pulled equipotential technical maintenance personnel to the equipotential.
The above is the basic operation flow of ± 800 kV DC transmission line UHV Live Working.
2.2 the principle of leverage micro-mentioned method and line charging operation related design tools and instruments
Since the ± 800 kV DC transmission line belonging UHV DC upwardly engineering design, most of the time it will link a large number of online double “L” and two “V” Insulator the string assembly methods.
In the charging operation process, if the string parts Insulator problems, it is necessary to use a positive lifting-wire transfer mechanical force Insulator string, to achieve the maintenance and replacement string Insulator.The practices employed to provide lines of industrial equipment has a relatively large mechanical load, so that once the repair defects found during Insulator string, it must be reset to avoid difficulties that may arise Insulator string wires by preventing the lateral displacement method.
In the “L” and “V” Live Working strings, transferring mechanical loads to be Insulator string generated mainly based on the principle of leverage with sword card micro-line job mention is completed.
First, the main advantage Insulator string instrument as a fulcrum as the main hole in the reserved construction, and special fixtures to the tower arm during installation, but also with two side panels using a wire tool knives on the line card effective installation.
Second, to promote high strength insulating rod, wire lifting means connected between the special fixtures in the form of a tower, and which is assembled UHV transmission lines, and allowed to form a string of mechanical force transfer system Insulator.
For mounting card sword, it is divided into action arm and operating arm, during its operation, not only to reduce the displacement distance of the line during design to ensure that the drive is formed sword card operating arm freely rotatable form, but also to make Insulator arm acts the leading role of the train load, at this time the inspection of mechanical loads Insulator string can be smoothly transferred to the mentioned line system, so as to realize the repair process Insulator string.
Reproduced indicate the source: