保护控制装置继电器回路抗干扰分析

电力系统保护控制装置中继电器线圈回路通常使用24 V电源供电,而CPU系统工作电源通常由5 V电源总线直接或间接供电,这导致装置开关电源设计复杂,需要进一步减少开关电源输出路数,简化电源设计,提高电源可靠性。为此提出取消开关电源中用于继电器回路的24 V电源输出,统一使用5 V电源,并用5 V线圈的继电器取代24 V线圈的继电器。分析了多个继电器同时动作对5 V电源系统的影响,试验证明其对整个5 V电源及CPU系统产生的影响很小,不会对系统正常运行产生影响。分析了在瞬变和浪涌干扰下,使用24 V线圈继电器时接点抖动的原因,以及使用5 V和24 V继电器时光耦短暂导通的原因。给出了抗干扰电容的放置位置、取值容量等电路改进措施。得出结论:在电力系统保护控制装置中使用5 V继电器和统一的5 V电源是可行的。

Analysis on Anti-Interference of Relay Circuits in Protection and Control Devices

In power system protection and control devices,the relay coil circuits are usually supplied by 24V power source,and the working power of CPU system is usually supplied directly or indirectly by 5 V power bus.Such a structure leads to the complexity in the design of device’s switching power supply,so it is necessary to reduce the output circuits of switching power supply to simplify the power supply design and improve power supply reliability.It was proposed that in the switching power supply the 24V output for relay coil circuit was canceled and the 24V relay coils should be replaced by the 5V relay coils,thus the unified 5V power source would be used.The influences of simultaneous action of multi relays on 5V power supply system were analyzed,and test results proved that both 5V power supply system and CPU system were slightly affected by the simultaneous action of multi 5V relays,and the normal operation of the whole system would not be affect by the replacement of relay coils.When 24V relays were used,the reason of contact chatter under the disturbances of electrical fast transient(EFT) and inrush current were analyzed,and when 24V and 5V relays were used the reason of temporary breaking-over of opto-coupler was analyzed too.Thus it could be concluded that it was feasible to adopt relays with nominal voltage of 5V and unified 5V power source for power system protection and control devices.