A lot of observation and reports in the world indicated that flashover voltage of insulator covered with snow or ice descended obviously 國內(nèi)外大量試驗觀察和報告表明,冰雪條件下絕緣子的閃絡電壓明顯下降,對電力系統(tǒng)危害極大。
So there is important implication value and academic value to systemic investigation of the effect of the existence of air gap to the flashover voltage along the ice - covered insulators 因此,深入、系統(tǒng)的研究空氣間隙中的放電活動對絕緣子串閃絡電壓的影響有著重要的工程應用價值和學術意義。
On basis of the analysis of the flashover processes in three kinds of icing states , it gives out the flashover mechanism of icing composite insulators and points out the minimum icing flashover voltage is related to the icing states 2 )通過對覆冰絕緣子三種覆冰狀態(tài)下閃絡過程的分析,提出了覆冰合成絕緣子的閃絡機理,并得到合成絕緣子的閃絡電壓與覆冰狀態(tài)有關。
The main tests and researches are as following : to study the ac flashover characteristic of composite insulator in different icing states by imitating tests in multifunctional artificial climate chamber , and analyze the effect of ice amount and icing water conductivity on flashover voltage , put forward a flashover mechanism by analyzing the icing flashover process . to study the ac flashover characteristic of composite insulator in different altitude and icing states together by imitating tests in multifunctional artificial climate chamber , and mainly analyze the effect of altitude ( air pressure ) and ice amount on flashover voltage , and investigate the flashover mechanism . to investigate the effect of high altitude and icing on the hydrophobicity of composite insulators 本文主要進行了以下試驗研究: 1 )在多功能人工氣候室里模擬不同覆冰程度下合成絕緣子的交流閃絡特性,主要分析覆冰量和覆冰水電導率對閃絡電壓的影響,并對其覆冰閃絡過程進行機理分析; 2 )在多功能人工氣候室里模擬不同海拔高度和覆冰程度綜合作用下合成絕緣子的交流閃絡特性,主要分析海拔高度(即氣壓)和覆冰量對閃絡電壓的影響,并進行閃絡機理分析; 3 )研究高海拔和覆冰對合成絕緣子憎水性的影響。
The study results show that the minimum ac flashover voltage decreases with the increase of the ice amount accreted on the insulator surface by an exponential law , and the down - trend of the minimum ac flashover voltage will slow gradually with the bridging of the shed of the insulators by icicles , both the average saturated ice amount and the special exponent m of effect of ice amount for different insulators depend on the radius of shed and the air - gaps of the sheds of the insulators , and that the ac ice flashover voltage decrease with the decrease pressure ratio p / p0 ( rise of the altitude ) by power - law for different esdd and icing - states when the altitude is from 4000m to 5500m . the special exponent n , which show the effects of altitude on the flashover voltage , is various with the type of insulator , icing - states and the surface status of iced insulator etc . , and that the minimum ac flashover voltage of iced insulators decreases by power - law with esdd or the freezing water conductivity for different ice amount and atmospheric 研究結果表明:在不同海拔高度和等值鹽密esdd下,絕緣子的最低交流冰閃電壓均隨覆冰量的增加而呈指數(shù)規(guī)律降低;當覆冰量增加到一定程度后,最低交流冰閃電壓隨覆冰量增加而降低的趨勢趨于飽和;不同絕緣子串的平均飽和覆冰量及閃絡電壓的覆冰量影響特征指數(shù)m均與絕緣子的盤徑和傘距等因素有關;在海拔4000 5500m之間,不同等值鹽密esdd和覆冰狀態(tài)下,絕緣子的交流冰閃電壓隨海拔高度的增加(氣壓的降低)與p / p0呈乘冪關系降低,氣壓影響特征指數(shù)n與絕緣子類型、覆冰類型、覆冰表面狀況等因素有關;當覆冰量和氣壓一定時,絕緣子的最低冰閃電壓均隨著等值鹽密( esdd )或覆冰水電導率的增加而呈乘冪關系降低,并逐漸趨于飽和。
All the transmission lines of west - east electricity transmitting project are inevitable to crossing the high altitude and icing areas . for the reducing of the air pressure and the absolute humidity , the electricity strength of insulators will drop obviously . therefore , it must be considered the effect on the insulators " flashover voltage caused by the change of altitude and ice when the insulation cooperation of transmission lines are being designed “西電東送”工程的所有輸電線路都不可避免的要經(jīng)過高海拔和覆冰地區(qū),由于大氣壓力和絕對濕度的降低會使絕緣子的電氣強度顯著下降,因此在進行輸電線路的絕緣配合設計時必須考慮到海拔高度和覆冰的變化對絕緣子的閃絡電壓影響。
Test results indicated : with the hoist of altitude , the increase of ice amount and the rise of pollutant , the average flashover voltage reduced . the character exponent generally depends on the insulator profile , ice amount , ice state and pollution severity etc . by means of a high - speed camera , a data acquisition system and high voltage test facilities , a series of the flashover processes on ice surfaces were record . the experimental results form this study and the subsequent theoretical analyses suggested : the thermal ionization of the air in front of an arc root resulted in arc movement ; the electrostatic force had an auxiliary effect of impelling arc propagation ; the electrical 通過對攝像機、數(shù)據(jù)采集系統(tǒng)及高壓試驗裝置記錄覆冰絕緣子表面閃絡電弧的發(fā)展過程的試驗結果進行理論分析得出:弧根周圍空氣的熱電離導致了電弧的發(fā)展,靜電場力對電弧的發(fā)展起到了加速作用,電擊穿僅發(fā)生在閃絡最終的跳躍階段;通過測量閃絡過程中的放電電壓、泄漏電流、閃絡時間、覆冰水電導率、電弧長度及電弧半徑等參數(shù),得到了不同階段電?。娀∑鸹‰A段、電弧發(fā)展階段及完全閃絡)的發(fā)展速度、臨界電弧長度均隨覆冰水電導率的增加而減小。
According to secondary electron emission avalanche ( seea ) theory , the effects of insulating materials , shapes , electrode structures of vacuum insulator on surface flashover and its mechanism , design optimization methods for vacuum insulator to improve surface flashover voltage by selecting insulating material , shape and electrode structure are reviewed 摘要根據(jù)二次電子發(fā)射崩( seea )理論,綜述了真空絕緣子的絕緣介質(zhì)材料、幾何形狀和電極結構對絕緣子沿面閃絡的影響和機理過程,以及從這三方面優(yōu)化設計真空絕緣子以提高其沿面閃絡電壓的方法。
The main work and conclusion for this paper is as following : according to the flashover test results of several kinds of iced insulators under positive voltage and negative voltage , this paper obtained : for the single porcelain insulator , the single glass insulator and the composite insulator bridged completely by icicle , the metal cathode ' s strong ability of emission electron is the primary reason that results in the lower negative flashover voltage ; the position difference of the high resistance district in method anode side results in that porcelain insulator cluster and glass insulator cluster have an evident effect of polarity ; when less ice and no icicle at the brim of the sheds , due to numerous non - polar arcs on the composite surface , the effects of polarity of composite insulator was lost using the test method of the average flashover voltage in the freezing period , dc flashover performances were investigated of several insulators with some typical structures and different material 本文的主要工作和結論如下:在人工氣候室內(nèi),根據(jù)不同覆冰絕緣子正、負極性下的閃絡試驗結果,得出負極性電弧金屬陰極的強電子發(fā)射能力造成了單片瓷、玻璃絕緣子及被冰凌橋接的合成絕緣子有較低負極性冰閃電壓;正極性電弧金屬陽極側產(chǎn)生高電阻區(qū)所處位置的差異使得瓷和玻璃絕緣子串具有明顯的極性效應;覆冰較少時,合成絕緣子表面出現(xiàn)數(shù)量較多的非極性電弧使合成絕緣子無極性效應。利用覆冰期內(nèi)平均閃絡電壓的試驗方法,對不同材質(zhì)和結構的絕緣子在覆冰、低氣壓和污穢共存環(huán)境中的直流閃絡特性進行了研究。試驗結果表明,直流平均閃絡電壓隨著海拔的升高、覆冰量的增加以及污穢度的增加而降低,且其特征指數(shù)與絕緣子結構、覆冰量、覆冰狀態(tài)、污穢度等有關。
Based on a series of tests and investigations , this paper draws some conclusions as following by processing and analyzing the test data . the minimum icing flashover voltage of composite insulators decreases with the increase of ice amount , and the tendency of it accords with exponential function . however , the relation of the minimum icing flashover voltage with icing water conductivity accords with power function 通過大量的試驗研究工作,對試驗數(shù)據(jù)進行擬合和分析處理,得到了如下結論: 1 )合成絕緣子最低冰閃電壓隨覆冰重量的增加而降低,且其下降趨勢符合指數(shù)函數(shù)規(guī)律,與覆冰水電導率的關系符合冪函數(shù)規(guī)律。