Voltage control of cage induction generator in micro hydro based on variable excitation

Compared to permanent magnet synchronous generator (PMSG), cage induction generator (CIG) has some advantages in off-grid micro hydro generation, because of its unique characters, such as economical, durable, and etc [1]. CIG can not provide excitation by itself and it is too weak to support heavy load. This article mainly describes a method to provide stepping variable excitation by a capacitor bank parallel connected to CIG. The capacitor bank switching equipment adopts the fuzzy control approach, only takes the terminal voltage as the control target. The paper designs the control strategy, and compiles the corresponding control program to achieve the automatic capacitor switching, which maintains generator's terminal voltage amplitude stable in the variable rotating speed. In order to verify the scheme's feasibility, this article designs a 3(kW) micro hydropower generation experimental system, and does the relevant verification tests.