Comprehensive Performance Study On Parallel Gap Device For500kV Composite Insulator

The lightning fault of high voltage transmission line has become the problem of the powersupply safety all over the world, so strengthening the lightning protection design for the HVtransmission construction is of great significance to build a more strong high voltage grid andensure safety and stability of power system. Considering the actuality that our power grid isdeveloping fast, grid structure is increasingly strong and SF6switch and recloser are used widely, itis conservative and one-sided for the traditional “jamming” measures of lightning protection.Studying economic and practical “dredging” lightning protection measure for high voltage powerline is imperative.For designing good-performance, economic and practical parallel gap device (PGD) for500kV transmission line composite insulator, this paper chooses a kind of traditional bar-shapedparallel gap device (BPGD). And on the basis of the protective principle, we designed another kindof new-style ring-shaped parallel gap device (RPGD). And for seeking insulation coordinationbetween500kV composite insulator and these PGDs, the lightning and switching flashovercharacteristics experiments on500kV composite insulator with parallel gap devices were carriedout in the National Engineering Laboratory (Kunming) for UHV Engineering Technology. Testresult shows that, the lightning flashover characteristics of insulator and PGD at altitude of2100m,is obviously lower than that at low altitude; for insulation interval of RPGD and BPGD, the bestinterval is3780mm.According to dredging arc principle of PGD, burning arc test of RPGD and BPGD werecarried out at Liao Ning high Voltage Apparatus Product Quality Inspection Company. Test showsthat, BPGD can dredge the arc far away from insulator; dredging and enduring arc capability ofRPGD is slightly inferior to BPGD.Based on V-t characteristics test results, this paper used electrical geometry method andPSCAD Electro-magnetic Transient Analysis Software to check the lightning outage rate oftransmission line with PGD. Consequently, it can prove the lightning outage rate of transmissionline with PGD corresponds to management goals in flat area.