Research On Corona Characteristics Of Single Conductor Under Foul Based On The Small Corona Cage

AC-DC transmission line corona will cause corona ion current, corona loss, audible noise and radio interference. They are directly related with electromagnetic environment of transmission line. With the increased voltage, electromagnetic environment has become a major technical issues must be considered on AC-DC transmission line design, construction and operation. Research on conductor corona loss under different surface conditions plays an important role on high voltage transmission line design and construction.Studying transmission line corona loss by corona cage is a cost-effective method. Corona cage can simulate conductor surface field strength conditions of transmission line. Corona cage is widely used in conductor corona characteristics study. At first, electrical parameters of corona cage, structural parameters, mechanical design and measurement applications are calculated. A laboratory small corona cage is designed and manufactured. Cross-section side length of corona cage is 1.8m. Corona cage is 4 meters long, 0.5 meters long at both ends of each protection segment.The corona cage is used for single conductor corona test. Corona onset voltage and corona loss of smooth conductor and ASCR under clean and foul are measured. Smooth conductor corona test under clean and foul is researched. In foul conditions, onset voltage of conductor is 28.63% less than that in clean conditions. Corona loss of conductor under foul is large than that under clean. Corona loss of conductor under foul is 29.9W/m more than that under clean with the voltage of 140kV. For ASCR, corona loss of LGJ-300/40 under clean and foul is 22.67W/m and 54.65W/m respectively. Corona onset voltage of LGJ-300/40 under clean and foul is 119.47kV and 80.00kV respectively. Corona onset voltage under clean is higher than that under foul. On one hand, contamination particles change the conductor surface, it makes conductor surface field strength down. On the other hand, contamination particle makes conductor corona appear under lower voltage.