降低1000kV变电站避雷器额定电压的可行性

为了优化绝缘配合,提高工程经济性,通过对特高压变电站金属氧化物避雷器(MOA)在不同系统过电压下吸收的最大能量的计算和对我国3个制造企业的MOA电阻片在荷电率为95%条件下的老化性能试验的分析,指出我国1 000kV变电站MOA的额定电压由828kV降低至804kV甚至更低(如780kV)是安全和可行的。额定电压降低至804kV或780kV,可使MOA保护水平分别降低2.9%或5.8%。变电站过电压水平随着MOA保护水平的降低而降低。通过对我国后续1 000kV输电工程变电站过电压计算表明,变电站雷电过电压水平和相地操作过电压可分别降低3%或5%,从而可以提高变电站绝缘安全裕度,或者降低绝缘水平,或降低对变电站进线段最大绕击电流的要求。同时通过对500kV和750kV系统MOA的额定电压进行分析,提出了其降低额定电压的建议。

Feasibility of Lowering the Rated Voltage of 1 000 kV Substation MOA

To optimize insulation coordination and improve the economy of project,we calculated the maximal absorbed energy of UHV substation MOA under different system overvoltage,and analyzed MOA varistor accelerated aging test results,which is with 95% chargeability of three MOA manufacturers in our country.It is pointed out that MOA of UHV substation is secure and feasible when the rated voltage is reduced from 828 kV to 804 kV or 780 kV,and this change decreases the MOA protection level by 2.9% or 5.8%.Moreover,it is revealed that the substation overvoltage level is lowered as the decrease of MOA protection level.Calculation of substation overvoltage of follow-up 1 000 kV transmission projects indicates that substation lightning overvoltage and the phase-to-earth overvoltage can respectively be lowered by 3% and 5%,which can increase the insulation safety margin of substation,so as to lower insulation level or reduce the maximum shielding lightning current of substation incoming lines section.In the mean time,the rated voltage of 500 kV and 750 kV power system is analyzed,and the recommendation of lowering their rated voltage is put forward.