Research On Characteristics Of DFIG-based Wind Farm Short Circuit Current And Its Influence On Line Protection

Chinese new energy large scale access grid development is swift and violent, because the protected access wind electric field leads to a lot of wind turbine and wind power transmission lines group malfunction situation has occurred. For the analysis of wind turbine group access to the influence of the relay protection, this paper studied the characteristics of current new energy station of extensive use of doubly fed wind turbine and the model characteristic, build the doubly fed wind machine electromagnetic transient model in the PSCDA/EMTDC simulation platform, transient characteristics of fault in the domestic wind motor group network short circuit test the recorded data were compared during fault fan, verified the model establishment of the doubly fed induction generator. K-means and volume weighted algorithm based on rotation speed of the fan, with information as the division of cluster index, clustering the network equivalent of fan wind field, wind field on the PSCDA/EMTDC platform the equivalent model is established, the fault results in the same fault conditions in contrast, verify the effectiveness of doubly fed wind motor group electromagnetic transient equivalent scheme.The actual wind field simulation system based on PSCAD/EMTDC platform, studied the failure characteristics of wind field in a variety of different wind speed, different fault types, different fault positions and different transition resistance situation. Discovery of DFIG wind farm side current during the fault frequency no longer keep frequency changes with the rotating speed, short front unit. Optical fiber current differential protection due to meet Kirchhoff’s current law, from the current frequency effect, can the correct action, but because the wind side current extraction is not accurate, the sensitivity of differential protection is reduced. Longitudinal direction protection phasor fault components, the positive sequence directional element, negative sequence directional element, steady distance protection and fault phase selection element due to the speed variable wind field with short circuit fault current frequency before the crew and change, action performance is seriously affected. Zero sequence directional element due to the neutral point of the transformer wind field ground, is not affected by.