吕梁干式变压器：吕梁干式变压器选择原则

吕梁干式变压器选择原则 　　
根据GB/T17468-1998《吕梁干式变压器选用导则》和国家公司国电农[1999] 191号《农村电网建设与改造技术原则》文件等确定的选择原则如下：
1）选用吕梁干式变压器的技术规范和参数应符合国家标准和行业标准，一般应按GB/T6451(油浸式吕梁干式变压器)、GB/T10228(吕梁干式变压器)、JB/T2426(所、厂用吕梁干式变压器)选择。选用时应明确是升压吕梁干式变压器，降压吕梁干式变压器，配电吕梁干式变压器，厂用吕梁干式变压器，联络吕梁干式变压器，单相、三相吕梁干式变压器，有载调压、无励磁调压，自冷吕梁干式变压器，还是风冷吕梁干式变压器。应选用通过省部级或相应级别鉴定的设备，优先选用国家经贸委和国家公司推荐的产品。
2)农网线路供电半径一般应满足下列要求： 400V线路≤0. 5km；10kV线路≤15km；35kV线路≤40km ；110kV线路≤150km。
农网主吕梁干式变压器的容量与配电吕梁干式变压器的容量之比宜采用1:2.5，配电吕梁干式变压器与用电容量之比宜采用1：1.5~1.8。
3）农村变电所的建设应坚持“密布点、短半径”的原则，向“户外式、小型化、低造价、安全可靠、技术先进”的方向发展，设计时考虑无人值班。设计标准可考虑10年负荷发展要求，一般可按两台主吕梁干式变压器考虑。
4)新建和改造的配网台区，应按“小容量、密布点、短半径”的原列建设改造.应选用低损耗配电吕梁干式变压器，目前主要是采用S9型和新S9型和少量非晶合金吕梁干式变压器。配电吕梁干式变压器的容量选择，要根据当地经济和生活用电水平，并考虑5年以上发展水平确定。64，73系列高能耗配电吕梁干式变压器要全部更换掉。
预装式箱式变电站小区应以规划布点为主，先确定一个合理的供电范围，再根据供电范围的用电负载情况计算配电吕梁干式变压器容量，城市可采用大容量一步到位方案，一般以每户4. 5—7. 5kW或每户60W/m²计算。
5)配电吕梁干式变压器的高压侧应采用国家定型的新型熔断器和金属氧化物避雷器。低压侧出线导线截面积不得小于35mm²(铝线〕，总吕梁干式变压器应采用空气吕梁干式变压器，并加装漏电保护器。
6)供电电压的允许偏差.可按G812325-1990 (电压允许偏差)、SD325-1989《无功导则》、GB50052- 1992《供配电规范》规定，即：
220V用户的电压允许偏差值为系统额定电压的±5% —10%；380V用户为±7%；10kV用户为±7%；35kV用户为10%。
线路的电流小于经济电流密度(国家规定：钢在小于3000年大负荷利用小时为3A/mm², 3000-5000为2.25A/mm², >5000为1.75A/mm²；铝分别为1. 65A/mm²， 1. 15A/mm², 0. 9A/mm²)。如果高压线路超过了压降5%，低压线路超过了4%，据《架空配电线路技术规程》规定，应选用有载调压吕梁干式变压器。
配置有载调压后，调压幅度可达±10%—±15%，甚至更大。且比无励磁调压级数多，调压精度高，调压的运行情况还可在线监侧。在安装线路压降补偿装备后，可以实现逆调压，以降低电压波动幅度。
35—110/10kV, 5000-31500kVA有载调压吕梁干式变压器的价格比无励磁调压吕梁干式变压器约贵15%-20%, 5000kVA以下约增加10%，这是由于它们分别配装组合式和复合式有载分接吕梁干式变压器以及增加匝数、引线，增大油箱和油量等因索引起的。对于10kV配电吕梁干式变压器，有载调压吕梁干式变压器比无励磁调压约贵1—2万元。

Transformer selection principle

According to the the GB/T17468-1998 power transformer selection guide and the State Power Corporation Guodian farmers [1999] No. 191 "rural power grid construction and transformation of the technical principles" document the principle of selection is as follows:
1) selection of the technical specifications and parameters of the transformer should be consistent with national standards and industry standards, should in general be GB/T6451 (oil-immersed transformer) GB/T10228 (dry-type transformers) JB/T2426 (station transformer) to select . Selection should be a clear step-up transformer, step-down transformers, distribution transformers, auxiliary transformers, interconnecting transformer, single phase, three-phase transformers, load tap changer, excitation voltage, self-cooled transformers, or air-cooled transformer. Should be chosen by the provincial and ministerial level, or level of identification equipment, preferred products recommended by the State Economic and Trade Commission and the State Powe企业账号：1611 0032 092 00213 086r Corporation.
2) the rural power line power supply radius should meet the following requirements: 400V line ≤ 0. 5km; 10kV line is ≤ 15km; 35kV line ≤ 40km; 110kV line ≤ 150km.
The capacity of rural power main transformer and distribution transformer capacity should adopt the ratio of 1:2.5, distribution transformers and power capacity ratio should be 1:1.5 to 1.8.
3) the construction of rural substation should adhere to the principle of "dense point, short radius" to "outdoor type, small, low cost, safe and reliable, technologically advanced", designed with unattended. Design standards may be considered the 10-year load requirements of the development generally in accordance with the two main transformers to consider.
4) new and modified the distribution network, according to small-capacity, point clouds, short radius of the original column construction and renovation should be used in low-loss distribution transformers, the key is the use of S9 and S9, and a small amount of non- alloy transformers. Distribution transformer capacity choice, according to the local economy and life consumption level, and consider the level of development identified in more than five years. 64,73 series of high-energy distribution transformers to replace them all out.
Prefabricated box substation district to plan distribution to determine a reasonable range of power supply, power distribution transformer capacity is calculated according to the scope of supply of electricity load, the city may be large-capacity step program, generally household 4. 5-7. 5kW or household 60W / m² calculation.
5) distribution transformer high side should be the national stereotypes of the new fuse and the metal oxide surge arresters. The wire cross-sectional area of ??low pressure side of the outlet shall be not less than 35mm ² (aluminum], the total switch air circuit breaker, and install leakage protection.
6) supply voltage tolerances can G812325-1990 (voltage tolerances) SD325-1989 "reactive guide", GB50052-1992 power supply specifications provided, namely:
Voltage of 220V user allowable deviation value of the rated voltage of ± 5% -10%; 380V user ± 7%; the 10kV user ± 7%; 35kV users 10%.
Power lines less than the current economic current density (state regulations: steel in less than 3,000 annual maximum load utilization hours for 3A/mm ², 3000-5000 2.25A/mm ²> 5000 ² 1.75A/mm; aluminum 1. 65A/mm ², 1. 15A/mm ², 0. 9A/mm ²). If the high voltage line over a voltage drop of 5%, the low voltage line more than 4 percent, according to the provisions of the overhead distribution lines, "Technical Specification should be used in load tap.
Configuration OLTC regulator magnitude of up to ± 10% - ± 15%, even greater. And series more than the non-excitation voltage, high precision voltage regulator, the regulator operation also monitoring side. After the installation of line drop compensation equipment, inverse voltage regulator to reduce the voltage fluctuations.
35-110/10kV, 5000-31500kVA price is higher than the excitation voltage transformer load tap changer is about 15% -20% more expensive, the 5000kVA following an increase of about 10%, this is due to them were equipped with a modular and composite OLTC and to increase the number of turns, wire, increasing the fuel tank and fuel due to the index. For 10kV Distribution Transformer, Yi regulating transformer excitation voltage of about 1-2 million more expensive.

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