非对称电流开断试验T100a电流零点di/dt及TRV峰值u_c的计算

Calculation of di/dt at Current Zero and TRV PeakValue u_c for Test-duty T100a

针对非对称短路电流开断电流零点di/dt及暂态恢复电压(TRV)峰值uc计算的复杂性,建立了非对称短路故障开断的等效电路模型,推导出首开极分别在大半波、小半波末过零熄弧的情况下,电流零点的di/dt及两参数TRV峰值uc的标幺值表达式,并得出两者表达式的一致性和关联性。经过分析与简化处理国家标准GB 1984—2014附录P中uc的修正公式,验证了推导结论的正确性。因此,电流零点的di/dt的标幺值表达式可以修正uc,计算结果表明修正误差和电流零点直流分量p、峰值时间t3成正比,当时间常数τ增大时,Δuc将整体增大,但均在标准要求的偏差范围内。最后,给出了非对称短路电流开断试验T100a时电流零点di/dt及Δuc的计算数值,可以作为T100a试验时的理论参考与依据。

Because the computational complexity of the di/dt at current zero and TRV peak value uo for asymmetric short-circuit current interruption, in this paper, the equivalent circuit models have been established for asymmetrical short-circuit fault breaking to gain the math expressions of di/dt at current zero and TRV peak value uo in the major loop and minor loop, in addition the di/dt and uc with the same expression. By simplified the expression of uo in the appendix P of GB 1984--2014, the derived conclusion is verified which is right. Therefore, it can use the expression of di/dt to modify u~ for asymmetric short-circuit current interruption. The calculation results show that the correction error is proportional to the percentage of DC component p and the peak time t3, and Auc is increased when the time constant T increasing. However, the error can meet the test requirements well. Finally, the calculated values of d/Jdt and Au~ are given in this paper, which can provide the theory and reference basis for the test-duty T10Oa.