How to quality control for 33kV prefabricated compact substation

Key points of construction quality control of 33kV box type prefabricated compact substation

Abstract:

At present, most enterprises are connected to the power grid by using 33kV box type prefabricated compact substation built by themselves. Therefore, the quality control of box type substation is very important, This not only affects the reliability of power supply, but also has a great impact on the normal operation and economic benefits of the enterprise. So it is very important to strictly control the quality of the installation process. This paper analyzes the construction quality control of the 33kV box type substation installation, puts forward the key quality control points of the installation and construction of 33kV box type prefabricated compact substation, and expounds the concrete measures of quality control

At present, the 33kV box type prefabricated compact substation level is usually connected to the power grid by the enterprise itself to ensure the safe operation of the power grid and the power supply reliability of the industrial and mining enterprises. The installation and construction quality of 33kV box type prefabricated compact substation also puts forward strict requirements accordingly. According to the installation process of a 33kV box type prefabricated compact substation, the quality control in the installation process is summarized

-------Project overview and control project division

Project Overview:

The installation of the 33kV box type prefabricated compact substation includes: 2 sz11-20000/33 main transformers; 33kV box type substation is single bus sectional connection, yb-40.5 intelligent box type substation is adopted, vd4-40.5 vacuum circuit breaker is selected in the switchgear; 11kv box type prefabricated compact substation is single bus sectional connection, xbg-12 intelligent box type substation is adopted, vd4-12 vacuum circuit breaker is selected in the switchgear; 11kv high voltage reactive power compensation installation is used Two sets of sets are set, with capacity of 6mvar, and 6 sets of TSC compensation mode are adopted

According to the installation specification and the current specification requirements of 33kV box type prefabricated compact substation, The quality control project is divided into the following main modules: first, the acceptance of equipment and construction materials; second, the installation of main transformer; third, installation of 33kV box type prefabricated compact substation, 11kv box type prefabricated compact substation and TSC reactive compensation box type prefabricated compact substation; fourth, installation of protection panel and AC / DC distribution panel; fifth, installation of high voltage cable, 11kv bus bridge and secondary cable; sixth, electrical equipment As a key element of quality control, its construction process is strict quality control, and the project quality control standards and specific implementation measures listed according to the installation characteristics of each unit are listed

--------Quality control of installation of each unit project

1. Acceptance of equipment and construction materials

As the first level of construction quality, we must ensure the quality of equipment and construction materials. For equipment, we should grasp three points during acceptance: first, appearance inspection, second, check that the equipment model and specification meet the ordering requirements according to the ordering technical parameters, and check some equipment to prevent imitation according to installation experience, such as 33kV acceptance Pt, full insulation and semi insulation shall be considered; for the incoming materials, two points shall be grasped during construction acceptance: first, appearance inspection, and check whether the materials meet the construction requirements according to the construction drawings, such as: size of foundation channel steel; size of grounding flat iron and galvanizing condition; the model and specification of secondary cable shall be checked to prevent some cable designs with spare cores, But in order to reduce the cost, the actual construction procurement of cables will reduce the number of cores, etc., and the above quality problems should be reworked in time

2. Installation of main transformer

Attention should be paid to the quality control points for transformer transportation: flat truck Highway transportation is generally adopted. When transporting by road, the main body shall not be more than 15 ° and 10 ° along the long and short axis direction. When transporting on the first class highway, it shall not exceed 25km per hour, and the secondary road shall not exceed 15km per hour, and 10km per hour during the transportation on the general road surface. When the transportation is on site acceptance, check the position of the main body on the transport vehicle Record the impact recorder (the product box cover is equipped with impact recorder). When the main body has a large displacement on the transport vehicle or the impact record in a longitudinal, vertical and transverse direction exceeds the specified, take photos and immediately inform the manufacturer to negotiate with the transportation department. If necessary, conduct internal inspection with relevant departments to determine whether the product is damaged

Attention should be paid to the quality control points for the installation of transformer body: check the drawings, the position is accurate, the oil level is clear and normal; the oil tank is free of oil leakage, the wheels are fixed reliably; the shock proof is firm and reliable; the surface of the body is clean and clean, and the paint is complete. The sealing of the connecting pipe between the moisture absorber and the oil storage cabinet shall be good, and the moisture absorption agent shall be dry; the on load voltage regulating switch shall be switched flexibly and reliably; the gas relay shall be provided with 1% ~ 1.5% of the raised slope, the oil storage cabinet end is allowed to be slightly higher, but the inclination of the axis and horizontal surface of the connecting pipe shall not exceed 4%; the grounding of transformer body shall be reliable and standard, and two points shall be grounded. The grounding of iron core and clamp shall be separately led to the main grounding network

Attention shall be paid to the quality control points for the installation of transformer accessories: the internal parts directly connected with the oil tank shall be cleaned, installed firmly, connected tightly and free of oil leakage; the bending radius from expansion thermometer to the fine pipe shall not be less than 50mm, and the pipe shall be free of flattening and sharp twisting. The long part of capillary pipe shall be placed neatly and the temperature sleeve shall be filled with oil; the transmission of on load voltage regulating switch shall be flexible It is flexible and accurate; the connecting washer, pipeline and lead wire between accessories and oil tank are neat and beautiful; the oil storage cabinet is well sealed, the oil level indication is clear and the device is not damaged; the high and low pressure casing is free of leakage; when filling oil, it is necessary to confirm that the sealing of transformer and related pipeline system is good, and all butterfly valves at the upper and lower connecting pipes of radiator shall be opened, and the ambient temperature shall not be lower than 20 ℃ when filling oil, If there is rain or fog during the filling process, it is better to stop filling oil and refill oil after fine days

When connecting high and low voltage bushing of transformer with high and low-voltage bus bar (or cable), attention shall be paid to quality control points: first, ensure the overlapping surface and connect closely, the locking device of connecting bolt is complete, and porcelain sleeve (high and low voltage) is not subject to external force and is firmly fixed; secondly, the bus line and its support, wire protection pipe and zero wire leading to transformer shall be easy to dismantle, and shall not hinder the voltage change maintenance The movement of the bracket is complete with corrosion protection

3. Installation of 33kV box type prefabricated compact substation, 11kv box type prefabricated compact substation and TSC reactive compensation box type prefabricated compact substation

As the 33kV distribution cabinet adopts integrated box, 11kv distribution cabinet adopts integrated box, TSC reactive power compensation cabinet adopts integrated box, 33kV box type prefabricated compact substation, 11kv box type prefabricated compact substation and TSC reactive power compensation box type prefabricated compact substation are installed with main quality control points:

3.1, Quality control point for foundation channel installation: it is appropriate to install box type substation on the foundation frame. When laying foundation, it shall comply with GB regulations. Channel steel shall be laid on the foundation surface (tank steel is different for box type substation size), and plane warping shall not be greater than 5mm; ventilation holes shall be reserved around the foundation, and 15 ° water distribution slope shall be reserved outside the ventilation hole; the bottom foundation of box type prefabricated compact substation shall be provided with internal foundation One double layer cable support shall be installed every 1m near the outlet hole; after leveling, the box type substation shall weld the bottom channel steel of box type substation with the foundation channel steel, and connect the grounding mark marked on the bottom frame of box type prefabricated compact substation to the grounding network

3.2. Quality control point of secondary cable threading in switch cabinet: for connection of power cable and control cable, pay attention to opening corresponding round holes on damping sealing ring according to cable core diameter. Connect cable through base plate and vibration damping sealing ring, connect terminal, insert heat shrinkable sleeve and connect it to cable connection point

3.3, Construction quality control point of high voltage power cable: cable entry is adopted for 33kV box type substation and reactive power compensation box type substation. After the cable construction, pay attention to its fixing mode. Single core cable shall be fixed by Aluminum clip. For three-core cable, reliable fixing point shall be added at the bottom of box type prefabricated compact substation to prevent cable from being stressed at hard bus; after cable construction is completed After that, the cable fire-proof mud shall be used for effective plugging

3.4. Fixed five anti-grounding piles shall be installed in each single switchgear of box type substation according to the maintenance requirements. The installation position of five anti-grounding piles shall meet the requirements of safety distance and be convenient for maintenance

3.5, Quality control points shall be paid attention to in the installation of some equipment in the switchgear: for gn27-40.5 series isolation, due to the limitation of the space of the box type substation, it is necessary to adjust the isolation in time. The isolated dynamic contact shall be synchronized in three phases. After the isolation is in place, the gap between the contact between the cutter head and the static contact shall be between 0.5mm and 1mm; the Pt and CT shell shall be grounded according to the regulations and the grounding is reliable; the frame shall be grounded Grounding shall meet the requirements; the fastening of the busbar must be carefully checked and inspected; after the equipment arrives, the construction personnel shall be organized to fasten the bolts at the connection of the busbar one by one

-------Installation of protection panel and AC / DC distribution panel:

It should be noted that the allowable deviation of verticality of cabinet and screen installation is 1.5 ‰, the joint between each other shall not be greater than 2mm, and the deviation of the surface of the train shall not be greater than 5mm; the actual test is 3mm, which is in full conformity with the requirements

Two incoming lines shall be set in the AC panel. In case of overvoltage, undervoltage, phase break or power failure, the automatic switching device of dual power supply can automatically switch from abnormal power supply to normal power supply

The battery installation in the battery switch cabinet shall comply with the following provisions: stable and flat, orderly arranged and correctly marked; when installing the battery bus, the bus, support and support parts and supports shall be flat, fixed firmly, the bus bar shall be straight and straight, and the bending degree shall be uniform; the bus shall pass through the wall terminal block, and the fixed and sealed shall be in good condition, and the bus layout shall be reasonable

The self start performance of inverter power supply is normal. During installation, the power cord shall be crimped with high-quality terminals. It is forbidden to wrap the power terminals directly on the terminal block

After the installation of protection panel, the wiring of each protection device shall be correct, the telemetry data shall be normal, the remote control and opening of the circuit breaker shall be provided normally, and the position signal of circuit breaker, isolation switch and ground knife shall be correct. Inspection of secondary ac part: the current riser shall be used to add single-phase current to three phases a, B and C respectively on the primary side, and the integrity check of secondary current circuit shall not occur, and no open circuit or series shall be found For other circuit phenomena, check the value and phase difference of the current of the protection and measuring circuit in the protection device panel, measure the metering current with clamp ammeter in the ammeter, and finally check whether the current display is correct in the background. Add single phase voltage to three phases a, B and C respectively on the secondary side of TV with booster, and check that all protection, measurement and metering voltage circuits on the corresponding bus shall have voltage, and their voltage shall be checked There should be no voltage on the bus bar, the voltage display value of the protection device panel and backstage machine should be correct, and the voltage of the measuring cabinet measured with Multimeter should be correct Add three-phase voltage, measure the phase sequence of protection, measurement and measurement voltage with phase sequence of voltage and the phase sequence of the added voltage. If the protection device has TV switching function, simulate the actual operation conditions, and meet the requirements of Pt cabinet operation and test position switching one by one

-------Installation of high voltage cable, 11kv bus bridge and secondary cable

For the construction of high voltage cable, three points should be considered: one is the fixation after the cable laying; the other is the production of cable head. The production of cable head shall be strictly implemented according to the installation process, especially when stripping copper shield layer and outer semiconductor layer, pay special attention to not damaging the main insulation and outer semi conducting layer when cutting the copper shield layer and outer semiconductor layer; when cleaning the surface of the insulation layer with cleaning paper, attention should be paid to the core wire end Wipe the semi conductive layer, and do not wipe back and forth; thirdly, the holes shall be blocked with fire-proof mud after the cable construction; prevent the cable core wire from being crimped tightly with the core wire, and the section between the cable nose and the core wire must be matched. The mould specification and core wire specification shall be consistent during crimping, and the number of crimping shall not be less than two

Attention should be paid to quality control points in the construction of secondary cables: for cable connection surface, it is strictly required that the current circuit shall not be less than 4mm2, voltage circuit shall not be less than 2.5mm2, and control circuit shall not be less than 1.5mm2; during construction, it shall be noted that the cable shall be treated with heat shrinkable sleeve, and the cable shall be armored in general, and metal armor shall be made to be grounded and effectively connected with the grounding end of cabinet; the guide of secondary circuit shall be no less than 4mm2; the voltage circuit shall not be less than 2.5mm2; the cable shall The cable shall not have joints, and the insulation voltage shall not be less than 500V. After the cable is laid, cable signboards shall be set at the first end, end and turning point. The circuit number of the secondary cable shall be marked with the circuit number. The handwriting shall be clear and not easy to fade. At present, the marking machine is adopted, which generally has no problems; to prevent the damage of cable core wire: when peeling with cable knife or electrician knife, it is not necessary to exert too much force , it is better to cut the outer insulation skin of the cable completely, and the inner layer cable skin shall be torn off to prevent damage to the core wire; the cable head is not properly clamped, the cable core wire is too long or too short. Before the cable core line is sawed, the size shall be measured, and the core line can be adjusted and replaced in the sequence, and it is not too long or too short; when the cable head is clamped, it is necessary to pay attention to straightening and alignment, and shall not be skewed; it is strictly prohibited to twist and screw the cable and flatten the armour The protective layer is broken and the surface is severely scratched; after the secondary cable construction, the construction cable shall be tightened at the terminal block connection point to prevent the false connection

For the construction quality control points of enclosed bus, the design and manufacture must meet the requirements of safety distance. For the installation of bridge, the shell shall be grounded by grounding wire between each two sections, and the bridge and support shall be grounded with flat iron to the main grounding network

-------High voltage test of electrical equipment

The factory test shall be carried out immediately after the equipment is delivered. After the equipment is installed, the handover acceptance test shall be conducted. It is mainly used to judge whether the equipment has insulation defects and quality problems after the equipment is delivered and installed. It is also an important measurement for the operation and transmission of power. All tests must be conducted in strict accordance with the relevant provisions of the handover test standard for electrical equipment in electrical installation engineering and timely Arrange the test report and deal with the problems in the test in time to ensure the safety of operation

The internal problems of equipment can be detected through high voltage test. When AC voltage withstand test is conducted for vacuum circuit breaker (model zn12-40.5), phase a of circuit breaker can not withstand voltage (when voltage is raised to 13.5kv, the voltage withstand instrument will trip), and it is judged that phase a vacuum bubble can not withstand voltage. Then contact the manufacturer for delivery and replacement in time to solve the problem

-------Acceptance of electric transmission and protection

The debugging of the protection function of the device is generally based on the type of relay protection device such as line, transformer and other relay protection devices, and the fixed value of simulation (or calculation), and the special relay protection tester is used to add current or voltage to the protection device, check the action accuracy of the device and drive the circuit breaker. The protection action information, switch position change information and action time data shall be displayed correctly on the backstage machine. At the same time, the transformer shall be provided with the protection action information, switch position change information and action time data Check some signals of non electric quantity, whether the gas, temperature and pressure signals of transformer body are displayed correctly on the backstage machine; the heavy gas and pressure signals shall jump the circuit breaker at each side of the main transformer, and the light gas and high temperature signals shall be alarm. The above quality control requirements that the actual position (data) of the field equipment is in line with the actual position (data) of the background monitor

Conclusion:

The quality control unit of electrical equipment installation is an important part of installation quality control to ensure the normal installation process of 33kV substation. In the construction of 35 kV Substation in Jinfeng coal mine, the management method has achieved good results, It can effectively guarantee the quality of the project.

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