TCSC暂态过程中晶闸管导通角特性的研究

RESEARCH ON THYRISTOR CONDUCTION ANGLE CHARACTERISTICS IN TRANSIENT PROCESS OF TCSC

当晶闸管触发角发生阶跃时 ,由于 TCSC电路固有的电磁暂态特性 ,使得电容电压过零点发生偏移 ,因此导通角不会立刻达到预定目标值。文章首先给出并证明了触发角阶跃变化与初始导通角之间的定性关系 ;然后通过分析晶闸管导通期间电容电压的解耦特性 ,推导出导通角的估算公式 ,定量地描述了暂态过程中导通角的变化规律。数字仿真验证了上述分析结论并进一步发现 :导通角变化趋势与 TCSC基频阻抗特性是完全一致的 。

When a step change in firing angle occurs the zero crossing of the capacitor voltage will change suddenly and the subsequent electromagnetic transients appearing in the TCSC will make the conduction angle not to reach the desired value instantaneously. This paper first presents and proves a theorem revealing the qualitative relationship between the initial conduction angle and the step change in thyristor firing angle. Then with the help of an approximate formula derived from the de coupling characteristics analysis of capacitor voltage during thyristor ON, the variation characteristics of the conduction angle in the transient process of TCSC could be easily quantitatively described. Finally the digital simulation verifies the result of the above studies and further shows that the fundamental frequency impedance characteristic is accordant with the variation of the conduction angle. This could well explain the reasons that TCSC exhibits the different transient response characteristics when choosing the different synchronizing signals.