Abstract: This paper puts forward the improvement and optimization of the main wiring mode of the distribution system of commercial super-high-rise buildings, reducing the reserve capacity of the storage transformer and optimizing the operation mode of the transformer, so as to achieve the purposes of energy saving, loss reduction and investment. Key words: connection mode of power distribution system in super high-rise building; Improve and optimize; Reduce the reserve capacity of storage transformer; Energy saving and consumption reduction
1. Overview
In recent years, with the development of economy, super-high-rise buildings have sprung up all over the country, which are generally built in the life and economic center of the city. Because of the many floors and high building height, the requirements for power supply reliability and fire fighting are much higher than those of ordinary high-rise buildings, and the corresponding construction funds are large, there are many operating equipment, and the safety operation standards are high, so the design complexity is also increased.
In order to develop more building area on a certain area of land, real estate developers will raise the height of buildings and develop super high-rise buildings. In order to facilitate sales, the use function of the building is more complicated. Generally, there are garages and equipment floors in the basement, podium buildings on the ground for offices or shopping malls, standard floors for offices, hotels and luxury houses, and a comprehensive building integrating catering and entertainment at the top. The height of super high-rise buildings abroad is nearly 1111 meters, and the number of floors has reached more than 311. The height of super-high-rise buildings in China has exceeded 611 meters, and the number of floors has exceeded 211.
at present, most super-high-rise buildings are planned: the height is about 211 meters, the total construction area is 1-1.5 million square meters, and there are more than 51 floors above the ground, of which the podium building has five floors for financial, commercial and catering facilities, and the main building is an office building, hotel or mansion. On the top floor, there are entertainment and catering. There are two refuge floors on the 13th-15th floor and 28th-31th floor, which are equipped with a fire-fighting fan room and a fire-fighting relay water pump room. There are power distribution room, diesel generator room, boiler room, parking garage, fire pump room, central air conditioning room, mechanical parking garage, etc. in the basement. It belongs to a kind of super high-rise building, and its functions are entertainment, catering, hotels, high-grade office buildings and serviced apartments.
in fact, the power distribution system of super-high-rise buildings is composed of power distribution systems of single buildings such as entertainment, restaurants, hotels, high-grade office buildings and serviced apartments, which are assembled, superimposed and compactly optimized in a vertical limited space according to their use functions.
2. Power distribution system
1. Load grade
Ultra-high-rise buildings generally have a large building area, a high density of people and complicated functions, and usually have a large power supply capacity. When various disasters occur in ultra-high-rise buildings, it is difficult to rescue and evacuate people, so the reliability of power supply is extremely high. Among them, the security of fire protection system is particularly important. The project belongs to a class of ultra-high-rise buildings and supplies power according to the first-class load.
2. Power supply selection
According to the Code for Design of Power Supply and Distribution System (GB 51152-2115), the primary load should be supplied by two power supplies. When one power supply fails, the other power supply should not damage the particularly important load in the primary load at the same time. In addition to being supplied by two power supplies, emergency power supply should be added, so two independent 11kV power supplies must be used in super high-rise buildings. 35kV power supply can be used where conditions permit). In addition, diesel generator set or EPS power supply should be set as emergency standby power supply according to the actual situation. This project uses 11kV dual-channel power supply (both power supplies should not be damaged at the same time). The power supply is led from the second section of different buses in the switching station of the nearby power supply department, and the power cable is buried into the main substation. The two power supplies are simultaneously supplied. When one power supply fails, the other power supply supplies all the primary and secondary loads. There are also two sets with self-starting functions.
3. 3.111kV main wiring of high and low voltage distribution system
: Single-bus sectional wiring mode is adopted, and the system is equipped with sectional bus contact switches. Two paths of 11 kV power supplies supply power at the same time, which are mutually standby. When one of the power supplies fails due to fault, the other path of power supplies all primary and secondary loads. 11kV outgoing line adopts cable radial power supply to each distribution transformer.
3.2 Low-voltage main wiring: single bus sectional wiring mode is adopted, with every two transformers as a group. The usual wiring mode is that every two transformers are used for emergency lighting and lighting of fire-fighting equipment, public equipment (elevators, pumps, fans, telecom room, computer room, security and building equipment management center), and the group also has generator sets. Every two transformers of the air-conditioning equipment are set as a group, which are standby for each other. They are respectively provided with bus connection and switch, two low-voltage incoming switches and bus coupler switches are on and off, and are interlocked by electrical and mechanical means. The particularly important negative load in the first-class load is provided with a special low-voltage bus, and besides two-way power supply, a diesel generator set is also provided as standby power supply. Its wiring is shown in Figure 1:
The distribution of all fire-fighting loads and important loads is a distribution trunk line drawn from two buses of the low-voltage system of the substation, and a double-power automatic switch box is set at the end of the distribution for distribution.
3.3 Power transformation and distribution station
The electrical equipment in super-high-rise buildings has a heavy load and complicated nature, and a large part of the electrical equipment is Grade I and II load. Usually, the scale of the substation is relatively large, and the equipment with large electricity consumption such as air conditioning room and water pump room in the building are arranged in the underground floor. According to the principle that the power transformation and distribution station should be close to the power load center in theory, it should be located in the middle of the building, but this will cause the phenomenon of backward transmission of electric energy. Therefore, the general transformer substation is usually located in the underground, which is convenient for equipment transportation and installation. There are many pipelines in and out of the general transformer substation, including high-voltage incoming cables, high-voltage and low-voltage incoming and outgoing cables, flame-retardant cables, fire-resistant cables, mineral insulated cables or pre-branched cables, and many enclosed buses. The pipeline in and out only adopts the way of going up and going out, which may cause frequent pipeline crossing and make the construction difficult. Therefore, it is appropriate to set trenches in the general transformer substation substation, and all kinds of cables enter and leave through the trench at the lower part of the distribution cabinet, and enclosed buses.
according to the national technical measures for the design of civil building engineering, the power supply radius of low-voltage lines should generally not exceed 211m. When the power supply capacity exceeds 5111kW and the power supply distance exceeds 211m, it is appropriate to consider adding a substation. If the building height exceeds 211m and the plane distance is added, the power supply radius of the upper part of the building will generally exceed 251m, the voltage drop may exceed the specified value, the power supply quality will decrease and the power consumption will increase. It will definitely affect the operation of elevators and other equipment. Therefore, for super-high-rise buildings with a building height of more than 211m, it is advisable to set up a substation in the upper part of the building to supply electricity to the tower elevators and part of the upper 1/3 floor. The substation in the upper part should be set up in combination with the refuge floor or technical floor, and the cable access line should be in and out, taking into account the transportation channel for installing equipment.
in addition, when the standard floor area is large, when the power supply capacity exceeds 5111kW and the power supply distance does not exceed 211m, we can consider setting up a substation in the middle of the building.
3.4
Low-voltage main wiring of the substation in the middle and top part of the building: it is the same as the low-voltage main wiring mode of the main transformer, and adopts the single-bus sectional wiring mode. The usual wiring mode is that every two transformers for fire-fighting equipment and public equipment are a group; Every two transformers of air-conditioning equipment are set as a group, which are standby for each other. They are respectively equipped with bus connection and switch, two low-voltage incoming switches and bus coupler switches are on and off, and are interlocked by electricity and machinery. The particularly important load in the first-class load is equipped with special low-voltage bus, and besides two-way power supply, there is also a diesel generator set as standby power supply. The above-mentioned low-voltage distribution connection mode, the transformer can not meet the actual operation requirements in actual operation, because the commercial buildings developed from the beginning of construction to the completion acceptance, the electrical equipment is powered on, the power comes first, and the high-voltage construction is completed, and then the power supply of other equipment is guaranteed: fire-fighting equipment, public equipment: water pumps, elevators, air-conditioning equipment, from the initial stage of power transmission equipment operation to full-load operation, it depends on the sales situation of the real estate, and some houses are purchased by customers. The public equipment and lighting system need power supply, and the air conditioning system also needs power supply. Both power supply systems need to put 1 transformers into operation. In fact, the power load is very small during this period, and putting 1 transformers into operation is far greater than the actual power load demand. Running according to the above-mentioned low-voltage connection mode causes: the loss of transformers increases, the waste of power resources and the investment increases.