磁环抑制变电站二次电缆瞬态电磁骚扰模拟试验及分析

Analysis and Simulation Test on Suppressing Transient Electromagnetic Disturbance of Secondary Cable in Substation with Magnetic Rings

在当今变电站中,智能化二次设备发挥了重要作用,其所需的许多电气量由二次电缆引入。二次电缆多处于开关场中,易受到较强的瞬态电磁骚扰。为了探究加装磁环对二次骚扰电压的抑制效果及影响因素,首先搭建了实验室模拟注入试验平台和变电站现场注入试验平台,从两个不同的电缆尺度开展了试验研究。利用注入法,通过容性耦合夹在电缆始端(开关场端)分别注入快速瞬变脉冲群和阻尼振荡波作为激励源,测量了电缆终端(保护小室端)芯线的对地共模电压,探究了磁环串长度、加装位置和材料等因素对抑制效果的影响。然后建立了试验平台的等效电路模型,利用传输线理论对加装位置影响进行了分析。研究结果表明:抑制作用随磁环串加长有不断增强的趋势,但磁环串增加到一定长度后,抑制效果的增加速率放缓;而为了增大抑制效果,磁环材料的选择应遵循磁导率适当高、阻抗损耗高、高频特性较好及饱和磁通密度大等原则;在保护小室端加装磁环可以抑制骚扰电压,在开关场端加装磁环反而使得保护小室端的芯线电压增大,最优加装位置的选择还与电缆实际敷设走向关系密切。研究结果能够用于变电站二次电缆骚扰电压的防护,提升二次设备及敏感线路的可靠性。

In contemporary substations,intelligent secondary equipment plays a crucial role,with many electrical pa-rameters required for its operation introduced through secondary cables.Secondary cables are mostly located in the switching field,making them susceptible to strong transient electromagnetic disturbances.To investigate the suppression effects and the influencing factors of added magnetic rings on secondary disturbance voltage,a laboratory simulation in-jection test platform and a substation injection test platform were constructed,with the experimental studies conducted on two different cable scales.Using the injection methods,electrical fast transient burst and damping oscillatory waves were injected separately at the cable initiation end(switching field)through a capacitive coupling as the excitation source.We measured the ground-to-core common-mode voltage at the cable terminal(protective chamber)and explored the influence of factors such as magnetic ring string length,installation position,and materials on the suppression effect.Subsequently,an equivalent circuit model of the test platform was established,and the impact of installation position was analyzed by using the transmission line theory.The research findings indicate that the suppression effect with the magnetic ring string increasing has a rising trend.However,the increase rate of the suppression effect slows down after the magnetic ring string is increased to a certain length;to enhance the suppression effect,the selection of magnetic ring materials should adhere to principles such as appropriate high magnetic permeability,high impedance loss,favorable high-frequency char-acteristics,and large saturation magnetic flux density;installing magnetic rings at the end of the protection chamber can suppress the disturbance voltage,whereas installing them at the end of the switching field will increase the core wire voltage at the protection chamber end.It is also revealed that the optimal installation position is closely related to the ac-tual cable routing.The research results can be applied to the protection of secondary cable disturbance voltage in substations,enhancing the reliability of secondary equipment and sensitive circuits.