Research on Adaptive Protection Scheme for Power Grid with DFIG

The high penetration of distributed wind power into the distribution network makes the transient characteristics of the distribution network more complex, which makes the traditional three-stage current protection difficult to adapt. In this paper, the transient model of doubly-fed induction wind turbine is analyzed, and the mathematical relationship between stator current and stator and rotor flux linkage is obtained. The analytical expression of DFIG active power and rotor reaction flux linkage is derived by theoretical derivation, and then the relationship between the current of wind turbine (field) after fault and the active power output at the moment of fault can be derived. A new scheme of adaptive protection with adaptive active output of wind turbine (field) is proposed for the lines of wind turbine (field) distributed in distribution network. Therefore, an adaptive current quick- break protection scheme based on timely adjustment of protection action value under different treatment conditions of wind field is proposed. A large number of simulation tests are carried out on the active distribution network established by PSCAD / EMTDC software. The results show that this method can effectively solve the problem of selectivity and sensitivity of the current quick- break protection action of the distribution network at the downstream position of the wind farm access point.