Application Research Of Overvoltage Protector For 10kV Distribution Networks

In recent years, along with the reconstruction of our country's large-scale city and countryside electrical system, power distribution systems in more and more cities are u sing overhead insulated conductor lines. Solving the problem of broken line fault by lightning properly to guarantee the insulation distribution system operating safely has already become very urgent in Zhejiang Province and even in the national distribution network system.In this thesis, firstly, the mechanism of 10kV overhead insulated conductor broken line fault by lightning and some existing main preventing methods are introduced. Then detailed researches are performed on performances of overvoltage protector which is a device preventing broken wire by lightning strike to overhead insulated conductor. They mainly contains: researches on arrester performance parameters of overvoltage protector, series connected gap performance parameters of overvoltage protector, the function of overvoltage protector to limit the lightning induced overvoltages in distribution lines, the installing density of overvoltage protector and the protection effect of overvoltage protector; experimental studies on line overvoltage protectors; theoretical simulation researches on the protection performances of lightning overvoltage protector in overhead lines. Through the analyses, the following conc1μsions are made: promptly shutting off the power frequency current flowing after the lightning current is the basic method to prevent the broken line accident struck by lightning on overhead insulated conductor lines. Overvoltage protectors composed of series connected gap and the lightning arrester have higher operating reliability, which is the main developing direction at present. At least one overvoltage protector should be installed between two adjacent towers, which can achieve better protection effect. If comprehensive protections are needed, overvoltage protectors mμst be installed on each tower. It has been proved by operating experiences of overseas and one domestic power supply bureau that, overvoltage protectors can effectively protect overhead insulated conductor lines from lightning trips and broken line faults.