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How to configure the distribution of residential district power transformer?
- Nov 11, 2017 -

1. Introduction

With the sustained economic and cultural development and vigorous building of a harmonious society, people's conditions for clothing, food, shelter and transportation are gradually being improved. Electricity consumption in residential areas has become an important topic of concern to the people. It is necessary to make household electricity use, but also to make the supply of electricity supply economy, high efficiency, minimize the various electrical losses as much as possible. Therefore, the power supply enterprises must strengthen the elaborate management of electricity marketing. In the meantime, the power supply enterprises and consumers should analyze and strictly comply with the relevant power regulations and design codes when planning, investigating and designing the power consumption load. Science Analyze and calculate the transformer configuration, select the transformer capacity rationally, and ensure the economic operation of the power supply department. At the same time, it will also reduce the unreasonable investment and the unnecessary burden of electricity loss. Not only to the new residential area to standardize the design, but also to some existing old residential district transformer configuration analysis, has been unable to adapt to the current actual situation of the transformer configuration, it is necessary to readjustment in order to achieve the power sector and Win-win with electricity users.


2. Promote the distribution room or box change

For a long time, residential district power supply is generally in the vicinity of 10kV transformer Taiwan (power sector or power unit of the public) low-voltage side of the direct lead to the district, and a transformer station area with a larger load, the majority Transformer station at the same time supply several residential areas and some fragmented residential electricity consumption, resulting in the transformer often overloaded Taiwan area. Especially in winter and summer peak period of electricity is even more serious, and even lead to overload transformer, burned transformer until the occurrence of the phenomenon. In addition, people are also increasing the reliability requirements of power supply. Therefore, we should change the power supply mode of new residential district, we must make scientific planning according to the current electricity demand and load characteristics of the majority of residents.


(1) New residential area construction supporting power distribution room

The distribution room is composed of high and low voltage switchgear cabinets and transformer room. The cables for high and low voltage in and out are used for cables and laid in the cable ditch, bridge or cable protection tube. At the same time, a fuse should be provided on the high voltage side of the transformer ) Or circuit breakers (large capacity), the low-voltage side to set up frame or molded case circuit breakers and set reasonable protection parameters in order to effectively protect the transformer. If some residential area public area smaller, you can also use box-type substation (referred to as box change). In this way, the transformer can be effectively protected, greatly improving the safety, reliability and stability of the power supply.

(2) Choose a variety of power supply.

The first solution: 10kV high-voltage side of the dual power into the line (the way through 10kV into the line of high-voltage switchgear mutual investment device to achieve the main backup power each other), the outgoing switchgear connected to the transformer; low voltage side of the single bus Segment, under normal circumstances, sub-operation. The second program: 10kV high-voltage side of the single power into the line, low-pressure side of the single-bus or non-segmented. The former method has high reliability but large investment and is suitable for higher-end residential quarters, especially those with high-rise buildings. The latter method has lower reliability than the previous one but saves investment. From the current situation, the latter way of power supply reliability has been able to meet the ordinary domestic electricity, the general use of the latter way, but considering the future development, distribution room should be reserved for installation of standby power supply high, low pressure into The location of the line cabinet. The above two points, the current new residential area should be supporting the establishment of distribution room or box change; the same time, 10kV power line into the line should be reserved (in order to ensure the reliability of power supply), the first phase can be accessed according to the actual situation only 1 10kV into the line.


3. Predict electricity load

Units of residential electricity load characteristics must take into account the level of the floor, whether the installation of elevators, fire pumps and other facilities, whether to set the central air conditioning and other factors. Also consider in addition to residential, the existence of community schools (kindergartens), shopping malls, entertainment and other public utilities. According to these actual situation to predict the residential electricity load.


At present, most newly-built residential areas in our country have 2 bedrooms, 2 rooms, 3 rooms and 2 rooms, and a very small number of 4 rooms and 2 rooms. Suite area is generally 90 ~ 130m2, a few more than 140m2. With the rapid increase in the number of residential appliances, especially high-power microwave ovens, induction cooker, disinfection cabinet, electric water heaters and other high-power electrical appliances into the ordinary family, the conventional design of power 4 ~ 6kW has been unable to meet the requirements of modern home, Urban household appliances survey, come to the following electricity load situation: General residential equipment capacity for the lighting capacity of 400W; entertainment capacity (including TV, VCD or DVD, combos, computers, etc.) 900W; Bathroom capacity (including washing machines, hot showers, Yuba, exhaust fans, etc.) 3000W; kitchen capacity (including rice cookers, induction cooker, microwave ovens, kettles, refrigerators, range hoods, etc.) 5000W; total capacity of 9300W.


According to the actual understanding and analysis, there should be a basic grasp of the load nature of urban residential electricity consumption. For example, the maximum load of residential electricity consumption in a city occurs before and after dinner, that is, the period from 18:00 to 20:00, and the time is slightly different depending on the season. At this time the load of electricity are: part of the lighting, the kitchen most of the electricity load, accounting for about 40% of residential electricity load, check the design manual required coefficient of 0.4 to 0.6, according to the actual situation, we design Take the 0.4 factor can be, then the unit residential electricity load is calculated 3.72kW.

4. Reasonable choice of transformers

According to the characteristics of residential electricity load, a reasonable choice of transformer is essential. To determine the appropriate capacity and number of transformers is not a breeze, the choice of large capacity, the number of stations will result in a waste of choice; the other hand, if there is no surplus capacity, there is no room for development, but also cause the transformer overload, Power supply reliability and safety can not be guaranteed. So, how to make a reasonable choice, the following an example to further analyze and explore this issue.


A residential district in a city has 20 6-storey buildings, each building has 4 units, each unit has 2 sets of households on each floor. There are 960 households in this district. Due to the different schedule of residents in the residential area, Of the living habits and peacetime test analysis, taking the required coefficient of 0.6, the converted total residential area after the calculation of the load Pjs:


Pjs = 3.72x960x0.6 = 2142kW


Since residents do not have reactive power compensation basically, so take load power factor COSφ = 0.7.


Taking into account the economic operation of the transformer, take transformer best load factor k is 0.8, then the transformer capacity S should be: S = Pjs / (k.cosφ)


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


Through the above calculation, combined with the larger total area of the district and the reliability of power supply, a power distribution room is built in each of the two places in the district. Each power distribution room is provided with 10 buildings and 4 1000kVA transformers are used for each Two power distribution rooms are installed (compared with two 2000kVA transformers, one for each power distribution room, with a large up-front investment but a relative increase in power supply reliability) to meet load requirements in the near and future years . This choice of four 1000kVA transformer benefits can also be reflected in, when the new tenants have not yet all stay, you can install a 1000kVA transformer in each place. After a period of observation, with the increase of load, it will be increased to 2 units in an appropriate period, so that the contradiction between overinvestment and load change can be solved well and the transformers can be deployed scientifically and rationally to pursue maximum benefits.


5. Conclusion

In the modern residential area, with the advent of a well-off society, the popularization of modern home appliances, people's living standards continue to increase, the demand for living electricity is also higher, the load on domestic electricity is still growing, both the nature of the load , Or the amount of load will produce rapid changes, the long-term residential load is difficult to predict, it is necessary to make the residential area of the electrical design is very perfect is impossible. Only by constantly exploring and summarizing experiences can we provide better service to residents' electricity consumption.