摘要
应用电磁暂态仿真计算EMTP程序,对在同塔双回线路中采用不平衡绝缘时,可将两相闪络有效锁定在低绝缘侧的最低不平衡度进行了分析,并提供了相应的绝缘配置方案。当线路采用平衡绝缘或绝缘的不平衡度较小时,雷击导致的两相闪络通常发生在两回线路中,即一回各有一相闪络;而随着两回线路绝缘水平差距的拉大,两相闪络将逐渐向低绝缘侧集中。利用该原理,通过保证两回线路之间足够的绝缘水平差距可将两相闪络锁定在绝缘水平较低的一回中,即实现以一回三相跳闸为代价来避免严重的双回同跳事故,从而提高线路的双回耐雷水平。计算结果显示,当220 kV和110 kV同塔双回线路的绝缘不平衡度达30%左右,或分别相差4片和3片绝缘子时,不平衡绝缘可较好地起到锁定两相闪络的效果。并且,该方案的防同跳效果在采用各种导线相序布置方式的双回线路上均稳定可靠,因而可有效地避免同塔双回输电线路发生雷击同跳事故。
When unbalanced insulation is applied to double circuit transmission lines on the same tower,the minimum degree of insulation unbalancedness,by which the lower insulation level is configured at one of the double circuit transmission lines to ensure that the phase-to-phase flashover always occurs at the side with the lower insulation level,is analyzed by electromagnetic transient program（EMTP）,and a corresponding insulation configuration scheme is provided.When the balanced insulation or the insulation with low unbalancedness is adopted to double circuit transmission lines on the same tower,the inter-circuit flashover caused by lightning stroke usually happens,namely there is a single-phase flashover in each circuit,however along with the extension of the difference in insulation levels for the two circuits,the inter-circuit flashover gradually turns to phase-to-phase flashover happening at the circuit with the lower insulation level.Based on this principle and by means of ensuring enough difference between insulation levels for the two circuits,it can make sure that when double circuit transmission lines on the same tower is lightning-stricken the phase-to-phase flashover only happens at the circuit with the lower insulation level,therefore the serious fault of simultaneous trip-out of two circuits can be avoided at the cost of trip-out of one circuit.Calculation results show that when the degree of insulation unbalancedness for double 220 kV or 110 kV circuit transmission lines on the same tower reaches to 30%,or in other word,the difference in insulator pieces of a string between two 220 kV circuits or two 110 kV circuits is 4 or 3 pieces respectively,the unbalanced insulation can restrict the circuit,where phase-to-phase flashover happens.Besides,the effect of such a measure is reliable and suitable for double circuit transmission lines on the same tower with various conductor arrangements of phase sequence to avoid simultaneous trip-out of both circuits for double circuit transmission lines on the same tower due to lightning stroke.
出处
《电网技术》
EI
CSCD
北大核心
2013年第3期765-772,共8页
Power System Technology
关键词
不平衡绝缘
同塔双回
同跳
耐雷水平
反击跳闸率
unbalanced insulation
double-circuit transmission lines on the same tower
simultaneous trip-out
lightning withstand level
back-flashover tripout rate
