The Research And Application On The Load Shedding Scheme Of Transformer Area Distant Overload

When two electric transformers run in parallel, if a transformer disconnects because of trouble-free or malfunction, causing overload operation of another transformer, the traditional transformer overload cutoff device removes part of the transformer feeder load, to ensure the safe operation of transformer. The traditional transformer overload cutoff device has drawbacks when operating. First of all, the traditional device can only remove electrical unit within this website directly, to achieve to cut the load of the whole line and station. But the cutoff lower station may have high risk (important) load users, whose supply reliability may be reduced. This can cause equipment damage and economic loss, and even threaten social and personal safety. Secondly, the overload criterion of traditional device is simple, and setting value and control strategy is single. So there is a high probability of overcut and undercut. Overcutting load expands the scope of the power outage, and undercutting load increases transformer operating risks. Thirdly, the traditional device for the mode of equipment operation has poor recognition ability. When the mode of operation changes, the device of external plate or internal control word must be synchronously adjusted, which increases the risk of wrong operation and setting.In this paper, transformer area distant overload shedding scheme is presented. The device exchange data through the optical fiber communication network and realize centralized criterion and disperse shedding for the master-slave mode by analyzing the distance and situ control strategy. Amount of terminal emulation is collected from the slave machine, and the host machine sends out tripping commands after overall judgment. Then the slave machine executes tripping commands, which realizes the transformer area overload shedding. When the transformer runs abnormally, the device removes selectively the secondary load in the lower substation, which not only protects the safe operation of the transformer, but also guarantees supply reliability of the important users.