变电站电气设备分级抗震设防原则研究

Study on Grading Seismic Fortification Standards of Electrical Equipment at Transformer Substation

摘要:

目前我国对电气设备抗震级别的规定低于国际上其他标准的要求,并且设防标准的确定考虑设防烈度、场地条件、设计地震分组等多种组合条件,不利于方便快捷地判断设备的抗震级别。通过对比国内外相关规范中对电气设备抗震设防级别的规定,分析电气设备进行分级抗震设防的优势,建议对我国的电气设备进行分级抗震设防。采用典型电气设备抗震可靠度指标作为参数,对建议的电气设备的抗震设防等级进行划分,提出高、中、低三等级原则。

Abstract:

The seismic fortification levels of electrical equipment have received more and more attention since the Wenchuan earthquake.The current seismic requirement level of electrical equipment in China is lower than that of other international standards,such as IEEE 693,IEC 62271,and JEAG 5003.In China,the seismic level of electrical equipment is decided by combining several conditions of fortification intensity,site condition,and classification of design earthquake,which makes it difficult to determine the seismic level of electrical equipment quickly and conveniently.By comparing domestic and foreign codes about the seismic fortification level of electrical equipment,the advantages of grading fortifications are summarized.Consequently,grading the fortifications for electrical equipment in China was proposed.In order to obtain the principles of this grading,the seismic reliability of electrical equipment was calculated.Design earthquake accelerations exceeding a failure probability of 2% in 50 years,which were higher than the normal value and obtained by survey,were used as calculation parameters.Two typical pillars of electrical equipment were chosen as calculation modals,and the seismic reliability of electrical equipment in ordinary porcelain and high-strength porcelain was calculated using the FOSM method.The use of design earthquake accelerations exceeding a failure probability of 2% in 50 years will meet the seismic target of not collapsing with strong earthquakes,which will further ensure the seismic safety of electrical equipment.The seismic reliability of high-strength porcelain equipment was obviously higher than that of ordinary porcelain equipment.It is an effective method to improve equipment seismic capacity through replacing ordinary porcelain by high-strength porcelain.The reliability results were used as indexes to determine the low,medium,and high levels.Specifically,peak accelerations of 0.1 g and below were considered to be at a low assessment level,and the peak acceleration was taken to be 0.1 g. Values of 0.1~0.4 g corresponded to the medium assessment level,and the peak acceleration was taken to be 0.4 g.Values above 0.4 g comprise the high assessment level,and the peak acceleration was taken to be 0.6 g. By comparing the peak acceleration with those of IEEE and IEC standards,it is found that the proposed seismic fortification for electrical equipment is more reasonable.The acceleration value of each seismic level is slightly lower than the values given by IEEE and IEC.