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How to scientifically configure residential distribution transformers

Author:ZTELEC   Update time:2018-09-05 10:53:14
With the development of the economy, people pay more and more attention to the quality of life, and the electricity consumption in the residential community has become a concern. It is necessary to make the households use electricity well, and to make the power supply enterprises economically and efficiently, and to minimize the various electrical losses as much as possible. Therefore, power supply enterprises must strengthen the refined management of electricity marketing. At the same time, power supply companies and power units must analyze and strictly comply with relevant power regulations and design specifications when planning, surveying and designing power loads. Analyze and calculate the distribution transformer configuration, reasonably select the transformer capacity, and effectively implement the economic operation of the power supply department, and at the same time reduce the unreasonable investment and unnecessary power loss burden of users. Not only the new residential area should be standardized, but also some existing old residential community oil-immersed transformer configuration methods should be analyzed. It is necessary to re-adjust the dry-type transformer configuration that can not adapt to the current actual situation. In order to achieve a win-win situation between the power supply department and the electricity users.

1 Promote the distribution room or box change

For a long time, the power supply mode of residential quarters is generally directly connected to the power supply in the vicinity of the 10kV transformer station area (the power supply department is changed or the unit used for power consumption), and the load on a transformer station area is relatively large. The transformer station area also supplies electricity for several communities and some scattered residential groups, causing frequent overloading of transformer stations. Especially in the winter and summer, the peak period of power consumption is even more serious, and even the transformer is overloaded until the phenomenon of burning the transformer occurs. In addition, people's requirements for power supply reliability are also constantly improving. Therefore, we should change the power supply mode of newly built residential quarters, and must make scientific planning according to the current electricity demand and load characteristics of the majority of residents.

(1) Construction of supporting power distribution room in newly built residential area
The power distribution room is composed of a high and low voltage switchgear room and a transformer room. The high and low voltage in and out lines are all cabled and laid in the cable trench, bridge or cable protection tube. At the same time, the high voltage side of the dry distribution transformer is also provided with a fuse. (When the capacity is small) or the circuit breaker (when the capacity is large), the frame type or the molded case circuit breaker is set on the low voltage side and the protection parameters are properly set to effectively protect the transformer. If some residential areas have a small common area, box-type substations can also be used. In this way, the transformer can be effectively protected, and the safety and stability of the power supply are greatly improved.
(2) Select a variety of power supply methods.
The first scheme: the 10kV high-voltage side dual power supply line is connected to the transformer through the outgoing switch cabinet; the low-voltage side adopts a single bus line segmentation, and the segmentation operation under normal conditions. The second scheme: 10kV high-voltage side single power supply line, low-voltage side single bus line segmentation or no segmentation. The former method has higher reliability, but the investment is large, and it is suitable for higher-grade residential quarters, especially those with high-rise buildings; the latter method has lower reliability than the former one, but the investment is relatively economical. Judging from the current situation, the power supply reliability of the latter method can meet the ordinary domestic electricity consumption. Generally, the latter mode is adopted. However, considering the future development, the power distribution room should be reserved for the installation of standby power supply and low voltage. The location of the cabinet. Based on the above two points, the current new residential community should be equipped with a power distribution room or box change; at the same time, the 10kV power supply line should be reserved for the incoming line position. In the first phase, only 10kV incoming lines can be connected according to the actual situation.

2 forecast power load

The characteristics of the electricity load per unit residential area must consider the level of the floor, whether to install elevators, fire pumps and other facilities, whether to set up central air conditioning and other factors. It is also necessary to consider whether there are community-run schools (kindergartens), shopping malls, entertainment venues, etc. in addition to housing. Based on these actual conditions, the residential electricity load is predicted comprehensively.

With the rapid increase in the number of residential household appliances, especially high-power appliances such as microwave ovens, induction cookers, disinfection cabinets, and electric water heaters have entered the ordinary households. In the past, conventional design considerations of 4 to 6 kW have failed to meet the requirements of modern homes. According to the survey and statistics of urban household electrical appliances, the following electrical load conditions are obtained: the equipment capacity of general residential buildings is 400W for lighting, and the electrical capacity for entertainment (including TV sets, VCDs or DVDs, stereos, computers, etc.) is 900W; Bathroom capacity (including washing machine, hot shower, Yuba, exhaust fan, etc.) 3000W; kitchen capacity (including rice cooker, induction cooker, microwave oven, electric kettle, refrigerator, range hood, etc.) 5000W; total electricity capacity 9300W.

According to the actual understanding and analysis, there must be a basic understanding of the nature of the load of urban residents. For example, the maximum load of electricity consumption of a city resident appears before and after dinner, that is, from 18:00 to 20:00, depending on the season, the time is slightly different. At this time, the electrical load is: part of the lighting, most of the electricity load in the kitchen, accounting for about 40% of the residential electricity load. The design specification needs to be 0.4-0.6. According to the actual situation, we design time. Take 0.4 coefficient, then the calculated residential electricity load is 3.72kW.
Box Transformer Substation


3 reasonable choice of transformer

According to the characteristics of residential power load, it is very important to choose oil-immersed distribution transformers reasonably. It is not a trivial matter to determine the appropriate transformer capacity and number. The capacity selection is large, and the choice of the number of units will cause waste. On the contrary, if there is no certain spare capacity, there is neither room for development and overload of the transformer. Power supply reliability and safety are not guaranteed.

There are 20 6-storey buildings in a residential area of ​​a city. Each building has 4 units. Each unit has 2 sets of households on each floor. There are 960 households in the community. Due to the different working hours of the residents in the residential area, according to the local The test habits of life habits and peacetime, the demand factor is 0.6, then the total calculation load Pjs of the residential community after conversion is:

Pjs=3.72x960x0.6=2142kW

Since the residential electricity has basically no reactive power compensation, the load power factor is COSφ=0.7.

Considering the economic operation of the transformer, taking the optimum load rate k of the transformer is 0.8, the transformer capacity S should be: S = Pjs / (k.cosφ)

S=2142KW/(0.8X0.7)=3826kVA

Through the above calculations, plus considering the large area of ​​the community and the reliability of power supply, a power distribution room is built in two places in the community. Each power distribution room is provided with 10 buildings, and 4 sets of 1000kVA transformers are used. Two power distribution rooms are installed to meet the load requirements of the near future and in the future. The advantage of choosing four 1000kVA transformers can also be reflected in the fact that when the new households are not fully occupied, they can install one 1000kVA transformer in each place. After a period of observation, as the load increases, it will increase to 2 in the appropriate period, so that the contradiction between excessive investment and load change can be better solved, and the transformer can be scientifically and rationally configured to pursue the maximum benefit.


ZTELEC professional distribution transformer manufacturer, to provide you with quality products and solutions.
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