变电站微机保护和监控系统电源干扰及抑制

雷击浪涌是低压电源线中发生最频繁的干扰源之一。为研究雷击浪涌对变电站微机保护和监控系统电源的干扰,首先通过分析电源线中雷击浪涌的入侵途径,提出了雷击浪涌危害的主要原因。然后基于过电压保护和电磁兼容两个方面的考虑,提出了低压电源线及低压电子设备的保护措施:一方面,根据低压电源系统防雷保护存在的问题,提出了完善低压电源系统的保护措施;另一方面,根据雷击浪涌的频谱中包含低频能量和高频能量的这一特征,提出了将瞬态抑制与滤波技术相结合的措施,即采用压敏电阻(MOV)消除低频能量,采用L-C低通滤波器滤除高频能量,从而有效地抑制雷击浪涌干扰。

Power Supply Interference and Suppression of Microprocessor-based Protection and Supervisory Control System in Substations

Lightning surge is one of interference sources that occur commonly in low-voltage AC power lines.The inrush path of lightning surge interference in AC power line is analyzed,accordingly,the main reasons of the damage to low voltage power lines caused by lightning surge is pointed out.In order to meet the demands of over-voltage protection and electromagnetic compatibility in low voltage system of the substation,aiming at the low voltage power line and electronic devices,the corresponding measures are taken to insure that the power system can operate in security and stability.On the one hand,on the basis of existing problems in lightning protection of low voltage power system, measures are proposed to perfect the system;on the other hand,based on surges frequency spectrum characteristics,including low frequency and high frequency energy,measures of surge suppressing and wave filtering are taken.Because electronic component is quite sensitive to electromagnetic interference and lower energy is enough to damage it,high frequency energy of lightning surge can not be neglected.Because of the factors above,the surge suppressor and wave filtering circuit are combined to suppress lightning surge interference,namely voltage-sensitive resistor(MOV) is adopted to eliminate low frequency energy of lightning surge and L-C wave filtering circuit can remove its high frequency energy, as a result,lightning surge interference is effectively suppressed.At last,with the ATP simulation software,the protection effect of power interference suppressor on electronic devices is analyzed,and the simulation result shows that it can restrain the over voltage existing in low voltage system and protect the electronic devices from lightning surge effectively.