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City network model of transformer and related technical problems

Author: WeiZhi From: www.yourpaper.net Posted: 2009-03-31 06:44:58 Read:
Abstract: the with the city to speed up the process, the transformation of the old city and new construction, in order to reduce the area of the GIS, but also to adapt to the cable cable, man, no oil and fire retardant fire requirements, part of substation with 110kV transformer model is an inevitable choice.In addition to 110kV oil-immersed transformer current transformer, can model selection......
Keywords: model 110kV gas insulated transformer fully-enclosed transformer transformer
, 110kV transformer type
With the city to speed up the process, the transformation of the old city and new construction, in order to reduce the area of the GIS, but also to adapt to the cable cable, man, no oil and fire retardant fire requirements, part of substation with 110kV transformer model is an inevitable choice.In addition to 110kV oil-immersed transformer current transformer, can model the:
1, dry-type transformer.Mainly resin molded products, currently in the 35kV power distribution system used in common, 110kV existing single-phase transformer group products in the operation, the main problem lies in the three-phase transformer coil surface design field is too high, the insulating long running reliability and adaptability to the environment has some problems.The IEC standard is amended, the new standard will be presented by the environment, climate and burning three test is an important method of performance appraisal of dry-type transformer insulation.
2, gas insulated transformer.Mainly refers to SF6 gas insulation transformer, insulating medium model gas better environmental performance will be developed in the future.Filled with gas pressure insulating medium in the transformer casing sealed, and the gas circulation cooling in the air under the action of body and the radiator, demand has better bearing sealing performance, and maintain annual leakage rate at a low level.At present in China has imported products in operation.Some manufacturers are also actively guide technology for realizing the localization as soon as possible.Technical standard for the corresponding IEC.
3, high temperature resistant insulating liquid immersed transformer.The solid insulating material insulating material of conventional paper insulation or high temperature resistant, filled with silicone oil, oil, high flash point liquid insulation medium, divided into different combination of mixed type, a mixed type, complex type, distribution transformers for general use can reduce the volume, improve the overload capacity, improve its fire retardant performance, is a choice between dry type transformer and transformer of the routine.Because of its moderate price, good environmental protection performance, has certain development space.The 110kV transformer, is also an alternative products.There are half mixed type and mixed type high temperature liquid immersed transformer used in.The IEC standards are developed.There is oil chromatography, gas protection problems, good high load loss.
4, cable, transformer, some foreign companies have introduced practical products, there are a number of transformer factory and the combination is developing a similar product, is expected to be in the oil, intumescent flame retardant without the 110kV voltage grade is better to solve the transformer.But the concept of longitudinal insulation and conventional winding wave process theory, used for cable transformer has a fundamental change.To study the insulation structure design and test technology.
two, ability to withstand short circuit in transformer
Electric or distribution transformer network city, due to its more voltage, impedance is relatively low, so the ability to withstand short circuit is also very important.IEC standard has recently revised, to test the ability to withstand short circuit in transformer to improve the requirements, from the past three times to nine times, and repeat the insulation test voltage short-circuit test value is changed to 100%, lightning impulse type test will be changed in the short road.The more stringent test.Thus the city network transformer put forward higher requirements, it is very advantageous to advance the operation reliability.According to the old standard through the short-circuit withstand ability of transformer test, whether I can pass the test requirements of the new standard is a question worth considering.Of course, the standard implementation also requires a process.But from the standards of the day, it should be tested according to the new standard, or violates the provisions of mandatory standards.
Three, energy saving
Energy saving problem of transformer network city, has received widespread attention.From the beginning of the last century seventy's, the country out of high energy-consuming products policy, distribution transformer has gone through 2 - 3 major upgrading process, the various types of dry and oil-immersed transformer are close to international advanced level.But from the efficient energy-saving requirements there is still a certain gap.At present the country out of the urgent requirement for resources and environmental protection, is developing a series of electrical products mandatory energy efficiency standards and guide the work of energy saving and high efficiency energy saving electrical certification logo products, supplemented by some policies to encourage.Distribution transformer is no exception.Should pay attention to energy saving work:
Energy saving of 1, transformer, must not sacrifice the operational reliability is the premise of.In any case, must adhere to the principle of reliability first thought, based on both the technical performance of products, further reducing the loss, improve product performance, to avoid the past have been upgrading products stable performance, overexcitation capability and overload capacity also decreased lessons.
Energy saving of 2, transformer, must adhere to the principle of key breakthrough.The first address energy consumption has a large quantity of products, promote energy saving work of similar products.For example, energy-saving power transformer is a full range of mandatory requirements, or through the investigation, to determine a general series products, such as small capacity section products formulated the confinement loss standard.Learning from foreign developed countries, attaches great importance to the small capacity of the distribution transformer standards, versatility and interchangeability requirements, in order to promote energy saving design of other products.
3 energy saving, consumption must be balanced transformer low-voltage power distribution system, reduce the loss, reduce voltage fluctuation, and the effect of improving power supply quality, must not be viewed in isolation the distribution transformer energy saving work.Miniaturization, standard of distribution transformer with point, limit power supply radius, reducing the low-voltage distribution network line loss, improve the quality of power supply should be the correct guidance, in addition to high power centralized power supply load need, should encourage the Department of building design suit one's measures to local conditions to the rational allocation of the transformer, the comparison between the economy, long-term operation of the rationality and increased distribution device for one-time investment, change now with the single capacity is selected more abnormal condition.4, copper and iron loss than the problem, namely the transformer load and no-load loss ratio, is composed of transformer loading rate decision.Generally speaking, the load rate is low, the consumption of copper and iron: ratio should be increased and high load rate, ratio should be reduced consumption of copper and iron, but this is built on the basis of silicon steel sheet material properties of continuous progress.Previous approach is to make two series, a series of suitable for city network, load rate is high: a series of suitable for rural power grid, load rate is low.Whether in the same series, the typical characteristics of city, rural power transformer capacity to grasp different, choose different copper iron loss transformer ratio.The transformer power used, because living dispersed, capacity is generally small, the load rate is low, can be made of copper iron loss ratio of the transformer, and the city network transformer - like living in concentrated load rate is high, selection, slightly larger and the copper iron loss is relatively small transformer.Variable instrument series capacity low-end and high-end do not insist on using copper iron unified consumption ratio.
Assessment of transformer loss, in addition to the active power loss, that the no-load and load loss sum, consideration should also be given to the reactive power loss.Core multistage joint process in this regard the no-load current, can be reduced to lower under water.Wound core transformer no-load current is very low, and have the advantage of.Impedance voltage generally change little, little effect on the reactive power loss, can not be considered.The active power loss of the transformer, the larger proportion, is the main impact of transformer loss.
5, at the launch of a new series of energy-saving transformer, can not but consider the series of various different sizes in product design material consumption, the energy saving at the same time, also cannot excessive increase in material consumption, the per unit volume of material consumption as an index, economy the series products of advanced technology assessment, comprehensive consideration.And should not simply the pursuit of material performance requirements, to reduce excessive dependence on foreign suppliers of materials.
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