孤立电网下大电动机软起动

Soft Start of Big Motor under Isolated Net

孤立电网是由柴油发电机组成的电压等级为3～11kV的中压电网。本文介绍了孤立电网系统怎样通过网频和网压两个闭环,保持电网稳定。大电机起动是很大的扰动,需要通过软起动缓冲。固态与液态软起动装置的主要区别在于:前者从电网支取的主要是无功功率,而后者支取有功功率。因为孤立电网的无功功率裕量大大超过有功裕量,所以,固态软起动装置比液态装置更加适合于孤立电网电动机软起动。

The isolated net, consisting of diesel engines and generators, is used in the area that the common electric power is unavailable. It supplies energy to a lot of electric equipments, including the motors with big volume. The starting of the motor results in the lowering of the frequency/voltage of the isolated net. The normal state can be maintained by the voltage/frequency loops. Because the output ability of the reactive power, in the case of the isolated net, is much stronger than the active one, the solid soft start apparatus prevails over the liquid one in such an application.