邻近三相电抗器的电缆线路接地线发热问题分析与治理

Analysis and Treatment of Heating Problem of Cable Grounding Wire Adjacent to Three-Phase Reactor

针对某500 kV变电站内邻近电抗器的电缆铠装层接地线出现异常发热的问题,建立了三相电抗器、电缆铠装层以及电缆终端模型,采用有限元数值计算方法对电缆接地线电流、电缆终端温度异常进行分析。接地线电流计算结果与实测值误差为1.8%,电缆终端最高温度计算结果与实测最高温度误差为3.6%,验证了计算模型的正确性。在此基础上,讨论了不同铺设方式下屏蔽体均对电缆线路接地线电流的影响以及屏蔽体的发热情况。结果表明,在三相电抗器底部铺设圆形和T形屏蔽体均能有效降低电缆接地线电流值,增加屏蔽体的面积能明显提高隔磁效果,且屏蔽体不会异常发热,可以安全使用。

Aiming at the abnormal heating of the cable armoring layer grounding line adjacent to the reactor in a 500 kV substation, the models of three-phase reactor, cable armored layer and cable terminal are established, the finite element numerical calculation method is used to analyze the abnormal rise of cable grounding line current and cable terminal temperature. The error between the calculated and measured values of grounding line current is 1.8%, the error between the calculated and measured maximum cable terminal temperature is 3.6%, which verifies the correctness of the model and method, and on this basis, the effect of the magnetic shield on the grounding line current under different placement methods and the heat generation of the magnetic shield are discussed. The results show that laying round and T-shaped magnetic shield at the bottom of the three-phase reactor can effectively reduce the cable grounding current value, and the increase of the magnetic shield area can significantly improve the shielding effect, the magnetic shield will not produce abnormal heat and can be used safely.