等离子体喷射触发型SF_(6)和SF_(6)/N_(2)间隙开关的触发性能劣化规律

Degradation Law of Trigger Characteristics of SF_(6) and SF_(6)/N_(2) Gap Switches Triggered by Plasma Jet

在江苏—白鹤滩±800 kV特高压混合直流输电工程中,采用等离子体喷射触发型气体间隙开关可以对可控避雷器进行旁路控制,具有响应速度快,绝缘恢复能力强,通流容量大等优势,应用前景广泛,但触发间隙气体氛围的优化选择尚有所缺失,间隙触发特性和寿命的提升仍有待进一步研究。搭建了等离子体喷射触发实验平台,研究了等离子体喷射触发气体间隙的触发性能劣化规律,分别在SF_(6)和SF_(6)/N_(2)混合气体中探究了间隙触发的临界电路参数,在确定的电路参数下进行触发寿命实验同时探究性能劣化规律。结果表明:相同绝缘强度下,当间隙电压为10 kV时,0.2 MPa SF_(6)氛围下间隙最低可触发电压为3.5 k V,而在0.266 MPa SF_(6)/N_(2)氛围下降低为2.6 kV;在最佳触发电路参数条件和相同绝缘强度下,实验初期,SF_(6)中间隙导通时延为~270μs,等离子体最大喷射高度为4.8 cm,最大喷射速度为1296 m/s,而在SF_(6)/N_(2)中间隙导通时延为~100μs,等离子体最大喷射高度为7.2 cm,最大喷射速度为1525 m/s,而随着放电次数的增加,间隙导通时延增加,等离子体最大喷射高度降低,最大喷射速度减小,直到间隙第一次触发失败达到间隙寿命,SF_(6)中间隙的触发寿命仅有695次,而SF_(6)/N_(2)混合气体中间隙的触发寿命达到了1540次。对可控避雷器用气体间隙触发开关的性能和寿命提升提供了理论指导,同时有助于其在工程领域推广应用。

In the Jiangsu-Baihetan ±800 kV ultra-high voltage(UHV)hybrid DC transmission project,used to bypass the controllable arresters,the gas gap switches triggered by the plasma jet bear the advantages in fast response,strong insulation recovery ability,and large flow capacity,having a broad application prospect.However,there are still a lack in their optimal selection of gas atmosphere for the trigger gap and a further study needed for the enhancement of trigger characteristics and trigger life.In this paper,by building an experimental platform of plasma jet triggering,the degradation law of the trigger characteristics of plasma jet triggering gas gap is studied.The critical circuit parameters of the gap triggering are respectively obtained in the SF_(6) and the SF_(6)/N_(2) mixture,and the trigger life experiment and the law of the performance degradation are carried out under the determined circuit parameters.The results show that,under the same insulation strength and with 10kV gap voltage is 10 kV,the minimum trigger voltage in 0.2 MPa SF_(6) is 3.5 kV,while it is reduced to 2.6 kV in the condition of 0.266 MPa SF_(6)/N_(2).Under the optimal trigger circuit parameters and the same insulation strength,at the beginning of the experiment,the gap conduction delay in SF_(6) is~270μs,the maximum plasma injection height is 4.8 cm,and the maximum injection velocity is 1296 m/s,while in SF_(6)/N_(2),the gap conduction delay decreases to~100μs,the maximum plasma injection height increases to 7.2 cm,and the maximum injection velocity increases to 1525 m/s.With the increase of discharge times,the gap conduction delay increases,the maximum plasma injection height decreases,and the maximum injection velocity decreases until the first trigger failure occurs and the trigger life is over.The trigger life of the gap in SF_(6) is only 695 times,while that of the gap in SF_(6)/N_(2) reaches 1540 times.This paper provides a theoretical guidance for the performance and life improvement of the gas gap trigger switches for the controllable arrester,and contributes to its popularization and application in engineering fields.