Transformer classification
Transformer is by means of electromagnetic induction, with the same frequency, between two or more windings, conversion of AC voltage and current and transmission of electric energy is a static electrical appliances. Its basic principle is: electromagnetic induction principle.
Chinese transformer products can be generally divided into ultra-high voltage (1000KV and above), ultra-high voltage (330KV and above, 1000KV below) transformer, 110(66)-220KV transformer, 35KV and below transformer.
Distribution transformers usually refer to the power transformers operating in the distribution network whose voltage grade is 6KV-35KV and capacity is 6300KVA and below directly supply power to the end user. Distribution transformers are widely used in industry, agriculture, urban communities and other terminal energy fields.
There are many classification methods of distribution transformers. According to the different voltage levels, divided into 6KV, 10KV, 20KV and 35KV transformer; According to the different insulating medium, divided into oil - immersed transformer and dry - type transformer.
1. Oil-immersed transformers are divided into:
A. Non-closed oil-immersed transformers are widely used in industrial and mining enterprises, agriculture and civil buildings.
B. Closed oil-immersed transformers are mostly used in oil and chemical industry where there are more oil and chemical substances.
C. Sealed oil-immersed transformer can be used for distribution in industrial and mining enterprises, agriculture, civil buildings and other places.
2. Dry-type transformer is divided into:
A. Encapsulated coil dry-type transformer, suitable for high-rise buildings, commercial centers, airports, stations, subways, hospitals, factories and other places.
B. Unwrapped coil dry-type transformer, suitable for high-rise buildings, commercial centers, airports, stations, subways, petrochemical and other places.
Annual output and forecast of distribution transformers
Since 2000, the market capacity of distribution transformers in China has increased steadily due to the improvement of urban and rural power grids. The proportion of distribution transformers in transformers has reached more than 40%. The annual output of distribution transformers is also increasing year by year (Figure 1). According to RMR statistics, from 2008 to 2015, the total annual output of distribution transformers in China is 4846594MVA.
In the next few years, power grid construction and urban and rural distribution network transformation is still the primary task of China's power industry. The State Council has decided to implement a new round of rural network renovation and upgrading projects. Two-thirds of the funds for the upgrade will be used to buy transmission and transformation equipment. The market for distribution transformers is expected to remain strong. RMR predicts that the capacity of distribution transformers in China will also grow steadily (Figure 2).
Transformer "energy saving and consumption reduction"
According to statistics, the loss of power transmission and distribution in China accounts for about 6.6% of the national power generation, among which the loss of distribution transformers accounts for 40-50%. Taking 2013 as an example, China's annual power generation was 5.32 trillion kilowatt-hours, and the power loss of distribution transformers was about 170 billion kilowatt-hours, equivalent to 1.7 times of the annual power generation of the Three Gorges Power Station in 2013 (about 100 billion kilowatt-hours), so the power loss was very serious.
With the deepening of China's "energy saving and consumption reduction" policy, the state encourages the elimination of high-energy consumption distribution transformers and the promotion of high-efficiency distribution transformers.
Some of the high energy consumption distribution transformers running in the network in China are not in line with the development trend of the industry and are faced with the need of upgrading and upgrading. The "Power Distribution Transformer Energy Efficiency Improvement Plan (2015-2017)" issued by the three ministries and commissions has clearly provided the annual elimination plan of high-consumption power distribution transformers (see Table 1).
Data source: Ministry of Industry and Information Technology 2015/08
As an important measure of energy conservation and emission reduction, many countries in the world have introduced corresponding policies to improve the energy efficiency of distribution transformers. In recent years, China has also accelerated the popularization and application of high-efficiency distribution transformers through the implementation of the distribution transformer energy efficiency improvement plan. Many transformer manufacturers in China have invested a lot of money to introduce foreign advanced manufacturing technology and equipment, and constantly develop low-loss transformers and transformers of various structural forms, such as SCB10 series of dry-type transformers and amorphous alloy cores and other low-loss products, which show the energy-saving potential of distribution transformers in China.
