1 Project Overview
The venues and related facilities of the Tanzania National Stadium meet the requirements of FIFA, IAAF and large international competitions. The number of spectators is 60,000. It is currently the largest modern stadium in the Middle East.
The total construction area of ​​the stadium is about 66 000 m2, with 5 floors above ground and a building height of 26 (stand) 33 m (cover shed). There are steel trusses and tensile membrane structure sheds above the auditorium.
2 load classification and power supply mode
2. 1 load classification
The Tanzania National Stadium is a large Grade A stadium that is powered by a primary load. The various power load grading and capacity statistics are shown.
2. 2 levels of load power supply
(1) The fire load is powered by the mutual power supply of the dual power supply terminals of the transformer room. The non-fire-fighting primary load is powered by the dual-channel power supply of the transformer room at the appropriate distribution point after the mutual investment.
(2) Evacuation lighting in emergency lighting uses the centralized battery of the emergency power system (EPS) as the backup power source. Diesel generators are used as backup power sources for fire-fighting pump rooms, fire-fighting centers, fire-fighting machine rooms, and other fire-fighting loads and venue lighting, sports technology room power, and emergency lighting in emergency lighting.
(3) Equipment that requires continuous power supply and data storage (such as timing scores, network switches, fire control equipment, security monitoring equipment, etc.) in a particularly important load, and uses a centralized battery of an uninterruptible power supply system (UPS) as a backup power source.
(4) The secondary load is to be supplied by a single loop of the double-circuit power supply of the transformer room at the appropriate distribution point for mutual power supply or reliable independent outlet (automatic input of the low-voltage bus-coupled switch of the transformer room).
2. 3 venue lighting power supply
The venue lighting uses metal halide lamps. The normal metal halide lamp can be restarted for 10 15 m in after power failure, which will affect the public order in the stadium and the normal operation of the game.
To solve this problem, metal halide lamps with electronic triggers that can be restarted instantaneously can be used. The faster the lamp power is restored, the faster the brightness recovery. According to the manufacturer's data, when the power is restored within 5 s, the brightness of the light source can reach 95% of the normal value, and after 1 m in, it can be 100% of the normal brightness. When the power is restored within 1 min, the brightness of the light source can be It can reach 50% of the normal value, and it can be 100% of the normal brightness after 3 m in. If the power supply reliability of the power grid is poor, the generator set must be set as the self-supplied power supply. If a metal halide lamp that can be restarted instantaneously is used, the site lighting will be extinguished within 15 s of the mains interruption and the generator set will be self-starting. After 15 s, the generator set will supply power and the lamp can be lit again and maintain the normal value of 50%. The above site illumination.
After economic and technical comparison, due to the high price of metal halide lamps that can be restarted instantaneously, the project funds are unbearable, and the lamps have at least 15 s of extinguishing state when the power source is switched from mains to generators, and other technical measures are needed. . Instead of using a metal halide lamp that can be restarted instantaneously, the project uses a common metal halide lamp. Starting from improving the reliability of power supply, the site lighting is divided into two groups to make the illumination evenly distributed. One group of site lighting is powered by mains as the main power source, diesel generator as the backup power source, and the other group is the diesel generator. As the main power source, the utility power is used as a backup power source. Before the start of a major competition, the generator set is directly started until the end of the race. At this time, 50% of the site lighting is powered by the generator set and is not affected by the mains failure; the other 50% of the site lighting is powered by the mains and is not subject to power generation. The impact of sudden failures in the operation of the unit, and the mains and diesel generators are alternate with each other, and the competition can be carried out as usual. Of course, during the power conversion and lamp re-ignition time, the illumination of the venue illumination drops to 50% of the normal value, and the color camera broadcast effect will be affected.
3 power supply
3. 1 municipal power supply
The project is a national-level large stadium, which should be powered by two-way power supply. However, the local area does not currently have dual power supply conditions and can only provide 11 kV single-channel power supply.
The substation of the project is divided into two parts: one is a transformer room, with 11 kV medium voltage power distribution equipment and two transformers, designed by the Tanzanian side; the other part is a low voltage distribution room with 0. 4 / 0. 23 kV low-voltage power distribution equipment, designed by the Chinese side. The two parts are independent of each other.
The low-voltage power distribution room is introduced from the two transformers in the transformer room to each of the 0. 4 /0. 23 kV power supply. The operation mode of the low-voltage power distribution system is single busbar section, and the busbar switch is provided, which can be automatically input. After the municipal power supply conditions are improved, the low-voltage power distribution system can meet the two-way power supply requirements without modification. The total electricity capacity of the project is 3 260 kVA. The power factor compensation adopts the low-voltage side centralized compensation method of the transformer, and the power factor after compensation is 0. 9. The electric energy billing is installed by the Tanzania power supply department on the high-voltage side, and the low-voltage power distribution room is no longer Set the energy meter.
3. 2 self-provided power supply
According to the investigation report, the local area can only provide one-way mains electricity, and the reliability of power supply is very poor, often with power outages. The project designed a diesel generator set that can guarantee all emergency lighting, fire fighting equipment and site lighting as an emergency power source.
4 low voltage power supply and distribution system
4. 1 Determination of the location of the substation
The location and quantity of the substation in the stadium must be determined as far as possible outside the load center. Special attention should be paid to verifying the voltage offset of the end equipment, and measures to reduce the voltage offset should be taken to ensure that the voltage offset does not exceed the allowable value. The project has two substation rooms, and the plane position is as shown in 1.
Stadium lighting is calculated according to the rating of the light source, and the voltage offset will affect the accuracy of the illumination calculation. Generally, when the voltage of a large gas discharge lamp is shifted by -5 %, the luminous flux is attenuated by up to 20%. The lighting of the project site adopts a light strip along the ceiling, and the length of the main line of the site lighting is large, and the length of the trunk line is very different (more than 120 m). TGJ 31 The 2003% sports building design specification stipulates that the voltage offset at the end of the lamp at important competition venues should not be greater than (1%). In order to reduce the voltage offset and balance the voltage at the end of the lamp cap, two substation rooms are set up on the first floor of the stadium, which are respectively used for power supply in the northeast and southwest half, and the site lights are respectively located at the positions of the east and west sides of the stand near the center of the light band. switch room. The voltage offset of the site lighting can be controlled at - 2 by adopting the measures of grouping and distributing the lamps, increasing the lighting distribution of the site lighting and trunk lines, and the branch trunks of the lamp control room to the ceiling lighting panel. Between 1% and 3%.
4. 2 distribution trunk system
The low-voltage power distribution system draws 400/230 V TN S system power from the stadium's power distribution room. The important load and large capacity concentrated load are radiated from the substation. The mains and trunk lines are laid in the ring channels of the first floor, the second floor, the fourth floor and the ceiling.
The distribution trunk system is shown in 2.
4. 3 generator set emergency distribution system
Generator emergency power distribution uses two methods.
(1) Power supply for the venue lighting. Directly allocated to the end of the venue lighting terminal distribution box automatically vote.
(2) Other important load power supply. The generator emergency power supply is sent to the power distribution room and the normal power supply is matched with each other. This is mainly considering that the generator room is adjacent to the 2 transformer room and far from the 1 transformer room. For the venue lighting, if the generator emergency power is sent to the 1 change room for mutual investment, the mains In the two cases of power supply and generator power supply, the length of the line is quite different, which cannot meet the requirements of the site illumination lamp for voltage offset.
In the design diagram, the genset start signal is taken from the auxiliary contact of the low-voltage main line switch of the power distribution room. Since the site lighting power supply is directly allocated from the generator emergency power distribution cabinet to the terminal distribution box, if the automatic start switch of the site light distribution box can be taken, the start signal of the generator set and the start of the power distribution room can be taken. The relationship of signal composition or) can further improve the reliability of power supply.
The neutral point of the generator is directly grounded outside, and the four-stage automatic transfer switch is adopted for the conversion between the generator and the mains power.
According to the load calculation, a 1 000 kW (common power) quick self-starting diesel generator set is selected. The generator room is located under the evacuation platform on the northeast side of the stadium, adjacent to the 2 transformer room, avoiding the dense flow of the main entrance and exit and the auditorium of the grandstand, minimizing the fire hazard and the adverse effects of noise and vibration during the operation of the unit.
Exhaust and smoke exhausted through the channel from the off-site slope to the green underground.
4. 4 normal lighting and emergency lighting distribution
(1) Site lighting distribution. The luminaires are grouped, and each group is led by the low-voltage power distribution room to the light distribution room and then split into the field distribution box on the shed. The intelligent lighting control module is installed in the field distribution box, which can not only control the lighting of the lighting according to the scene, but also control the power supply delay of the lighting through the program, avoiding the large current impact caused by the simultaneous starting of multiple lamps. In order to suppress the stroboscopic effect of the gas discharge lamp and ensure the quality of the TV broadcast picture, the adjacent lamps of the site lighting are cross-distributed with different phase sequences. There is overhaul lighting on the shed and the 36 V low voltage power supply.
(2) Auditorium lighting distribution. The auditorium is equipped with normal lighting and evacuation lighting. The lamps are arranged on the shed and the distribution is similar to the site lighting. The auditorium lighting is centrally controlled in the light control room. The iodine-tungsten lamp for evacuation lighting does not start normally, and lights up directly during emergency.
(3) Evacuation platform lighting distribution. The 2nd and 4th floor evacuation platforms are provided with normal lighting and emergency lighting. A distribution point is set at an interval of about 80 m along the evacuation platform. Each distribution radius is about 45 m. The main line and the trunk line are laid along the ring line slot. Due to the long distance of the evacuation platform and the scattered distribution points, normal lighting and emergency lighting are controlled by intelligent lighting system.
(4) Square lighting distribution. Square lighting is a combination of high pole lights and garden lights. It is distributed from the distribution room scattered around the first floor of the stadium and controlled by an intelligent lighting system. The square lighting distribution adopts the TT system, and the lamp body is directly grounded.
4. 5 selectivity of distribution protection
The selectivity of distribution protection is an important part of improving the reliability of power distribution systems. GB 50052 1995% power supply and distribution design specifications stipulate that the action of the upper and lower protection appliances of the distribution line should be selective, and coordination should be coordinated between the levels. As far as the stadium is concerned, the selectivity of the power distribution system should be guaranteed. In the specific design, the work of accounting selectivity is cumbersome. The practical method is to check the circuit breaker protection matching table provided by the circuit breaker manufacturer. At present, the well-known brand circuit breaker manufacturers can provide the upper and lower switch selective matching tables of their respective products to facilitate design and selection.
5 design experience
5. 1 Determination of the number of transformers
In addition to sports competitions and training, large stadiums often have cultural and sports activities, conferences, catering, accommodation and other ancillary houses for normal use. Considering the characteristics of the electric load and the economic operation conditions of the transformer and the reliability of the power supply system, the stadium should select the power supply scheme of multiple small-capacity transformers. Large-scale electrical equipment that is only used during the competition should be equipped with a dedicated transformer, and usually exits. By reducing the number of transformers, the operating transformer load rate is within the scope of economic operation, achieving energy saving.
The Tanzania National Stadium is limited by the distribution radius and requires two transformer substations. Because the stadium is only used for training and competition, there is no auxiliary room for other purposes. In order to simplify the power distribution system, there are 2 transformers in each transformer room, and the low-voltage single-bus line runs in sections and has a busbar switch. During non-competition, the transformer distribution room at T2 can be connected to their respective bus-coupled switches, each powered by one transformer and the other transformer exiting operation.
5. 2 intelligent distribution system
Intelligentization is the development direction of the current power distribution system. The intelligent power distribution system can realize centralized data acquisition, processing and monitoring to achieve telemetry, remote adjustment, remote control and remote signaling of the power distribution system.
Through the variable distribution intelligent control system, harmonic analysis, voltage fluctuation detection, neutral current monitoring can be performed to improve power quality; power consumption can be observed at any time to reduce operating costs; early warning and analysis of faults can be provided, accidents can be reduced and accelerated Troubleshooting. Like the Tanzania National Stadium, which has a high load rating, a large electrical load, and two large stadiums with two substations, setting up an intelligent power distribution system can raise the management level to a new level. Due to the limitation of engineering investment, the project did not have a variable power distribution intelligent control system.
5. 3 generator room settings
The project has a generator room, two power distribution rooms, and the generator room is adjacent to one of the power distribution rooms. For the load of another power distribution room, the voltage deviation between the normal power supply and the emergency power supply line is quite different. In both cases, the voltage deviation is quite different. In the design, the emergency response from the generator room to the power distribution room is adopted. Measures for the mains section of the power supply. If a generator room can be set up near each transformer room, the power distribution system will be more reasonable, but the investment and use management costs will need to be increased. The noise, vibration, fire prevention and other problems will make it difficult to select the location of the equipment room. The engineering generator house is set up according to local customary practices. In fact, the stadium can consider the temporary rental of mobile generator sets to solve the emergency power supply problem.
6 conclusion
The Tanzania National Stadium project has been basically completed and passed preliminary acceptance. Efforts to make power supply and distribution systems safe, reliable, and economical should be the designer's pursuit. It is hoped that through the analysis and summarization of the power supply and distribution system of the Tanzania National Stadium, it will play a role in inspiring the jade, and provide reference for the electrical designers to engage in stadium power supply and distribution design work.
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