Analysis on Requirements of Islanding Detection Systems for Distributed Induction Generators

Abstract

Islanding of induction generators for wind power generation systems can cause a variety of problems and must be prevented islanding. In Japan, Ministry of International Trade and Industry (MITI) revised “technical requirements for distributed generators on distribution systems” in 1998. The technical requirements do not require islanding detection systems for wind power generation systems consist of induction generators. However, if reactive power of induction generators and capacitors of distribution systems are closely matched, the islanding detection by ordinary relays becomes difficult because of self-excited of induction generators. In this paper, frequency of induction generators after theirs disconnection from grids, so called the self-excited frequency, is studied by analytical procedures. The analytical procedures and related simulations, using the Electro-Magnetic Transients Program (EMTP) and Transient Network Simulator (TNS), are described. The analytical results are presented and compared with the corresponding obtained simulation results.