Development of short circuit test of power transformer in China
It is difficult to avoid some short circuit events when the transformer is running in power system. Depending on the severity of the short circuit event and the strength of the transformer's short circuit resistance ability, sometimes it is safe and sometimes damaged. The damage of one distribution transformer will affect a factory enterprise in a short time, while the short circuit accident of one distribution transformer will affect a city area, and the replacement is more difficult. The repair will take 2-3 months. Therefore, it is always a matter of great concern to improve the short circuit resistance of power transformer, and also the main goal of the manufacturing department.
Before 1990s, there were only four high current laboratories (stations) in Xi'an, Shenyang, Shanghai and Beijing. The facilities were mainly for the switch capacity test for the switch industry, but also the distribution transformers. In the early and mid-1980s, Shenyang Transformer Research Institute was responsible for the unified design of sl7 and old s9-30-1600kva / 10kV distribution transformers. The prototype produced by each factory has been tested in the above laboratories (stations). The sl7 type test is qualified for 14 and the old S9 type is qualified for 12. After the test is successful, the new S9 type was trial manufactured. 37 new S9 transformers were qualified in the first batch of tests, and the qualified rate of new S9 reached more than 90% (Kema in Netherlands tested foreign distribution transformers with a primary qualification rate of 50%). By 1996, about 300 power distribution transformers had been tested in laboratories (stations) including S7 type.
In the past decade, China has done a lot of short circuit tests on distribution transformers, and improved every damage, so that the qualified rate can reach more than 90%, much higher than 50% of the foreign qualified rate. This has been proved in the actual operation of the power grid and has achieved gratifying results. It can be said that the basic solution of the short-circuit strength of distribution transformer depends on "practical test", which is a very important experience.
There is no base for testing power transformer in China, so the ability of short circuit resistance of power transformer is difficult to solve. In 1986, the State Planning Commission approved the construction of Shenyang Hushitai high current test station, which was financed by the state and approved to consult with EDF company of France. After years of work, the first phase of the project was completed by the end of 1993, 220kV network was built and 2 1200mva / 0-224kv were installed. After being accepted by the national expert committee, it was opened in January 1994. A large number of distribution was carried out in 1994 and 1995 After the transformer test, the short circuit test of 110kV power transformer was carried out in 1996.
Short circuit test of 110kV power transformer
110kV power transformer is the main transformer in China's transmission and distribution system, and the output accounts for about 1 / 5 of the total output of transformer. The statistical data from 1995 to 1996 show that the short circuit accident of 110kV transformer accounts for 5O% of the total accident in this class, and it is on the rise. Therefore, how to improve the short circuit resistance of this class power transformer has become the main topic in Zengcheng conference in Guangdong Province. It is generally accepted that the best way is to verify it by short circuit test.
From 1996 to the first half of 2005, due to the attention of power department and manufacturing enterprises, more than 60 factories have conducted short circuit tests on 80 110kV (2 of them are 66kV in Northeast China and 132kV for export) (including 4 sets of Shenyang Transformer Co., Ltd., 3 Xinjiang special transformer Electric Co., Ltd., 2 Nantong Youbang Transformer Co., Ltd., Changzhou Transformer Co., Ltd The qualification rate of primary test is more than 96%. The qualified transformer with a qualified rate higher than 10kV.
In order to achieve a qualified test, these factories have invested a lot of manpower and material resources. In the process of product development, they have made some efforts in design, technology, production and management, which undoubtedly improves the comprehensive quality of the enterprise. In the first half of 2001, 28 of the 45 products tested have been operated on the power grid, and the one with the shortest operation time has been in operation for several months. One of the new products of shentransformer has been running for more than 5 years, and it has been popular with users. Based on the test data, these factories improved the product design structure, and put them into power grid in batches according to the standard, so no short circuit accidents were counted in the future.
The statistics of Wuhan High Voltage Research Institute of state power company and China Academy of electric power science from 1995 to 1999 show that the short circuit accident of transformer has decreased from 50% to 40% in the past. This is mainly due to the above high reliability transformer put into operation, which has brought about the improvement of system operation reliability. It should be said that the short circuit accident of 110V transformer has been preliminarily stopped.
The short circuit test of 110kV transformer should be further expanded
At present, there are 60 factories that normally supply 110V power transformers in China. Only more than 100 factories have been tested for short circuit of 110kV transformer, accounting for 55% of them are preparing conditions and doing short circuit test. This requires the support of users and actively adopt the products that have been tested, so that it can play a role in the system. In terms of manufacturing plants, we should carry out work in terms of design and technology, make sufficient material preparation, raise funds and put them into practice. It should also be pointed out that factories that have not done short circuit tests on transformers should be carried out in a timely manner so that the order will not be affected or even disqualified from production.
Jinghu Electric Transformer Co., Ltd. is a professional manufacturer specializing in research, design and manufacture of special transformers and reactors. Advanced technology and equipment, complete testing means, enterprise after 20 years of practical experience. Transformer, dry-type transformer, power transformer, transformer price, rectifier transformer, three-phase transformer, amorphous alloy transformer, voltage regulator, voltage regulator, power regulator, AC voltage regulator, voltage regulator manufacturer, voltage regulator price, Charger, inverter, controllable rectifier transformer (single-phase transformer, three-phase transformer, six phase transformer, twelve phase transformer, excitation rectifier transformer, electroplating rectifier transformer, electrolytic rectifier transformer), angle transformer, decompression starting autotransformer (QZB) and high voltage starting reactor (qksq), salt bath furnace transformer, resistance welding transformer, special autotransformer for lighting energy-saving equipment Transformer, high voltage test transformer, large current generator, special transformer for high frequency medium heating equipment, high voltage transformer for prison high voltage power grid prevention equipment (not afraid of short circuit and lightning strike), current limiting high voltage transformer for picture tube recovery, neon impact transformer, machine tool control transformer (BK, BKC and JBK), communication electronic power transformer (EI, C and ED) Voltage stabilizing transformer, isolation transformer and various electromagnetic coils. Reactor: including three-phase incoming reactor, two-phase incoming reactor, DC smoothing reactor, shunt reactor, filter reactor, smoothing reactor, input-output reactor, balance reactor, inverter special (input, output, DC) reactor, series reactor, capacitor compensation series reactor, power filter special reactor, incoming reactor and current limiting reactor Reactor, all kinds of false load reactor, variable magnetic control reactor).
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