
{"publication_number": "US-2015300320-A1", "abstract": "the present invention relates to a method for injecting electrical energy into an electrical , three - phase grid , comprising the steps of : injecting current by means of an injection unit at a grid connection point , detecting an asymmetry in the grid , in particular a negative sequence component in the grid , injecting an asymmetrical current portion into the grid for , at least , partial compensation of the detected asymmetry , with injection of the asymmetrical current portion taking place such that the injection unit behaves like a consumer .", "application_number": "US-201314442050-A", "description": "fig1 shows a wind power installation 100 with a tower 102 and a nacelle 104 . a rotor 106 with three rotor blades 108 and a spinner 110 is located on the nacelle 104 . when in operation , the rotor 106 is set into rotation by the wind and thereby drives a generator in the nacelle 104 . the following is explained with reference to fig2 a , 2 b and 2 c . the fundamental frequency content of voltages ( and currents ) is represented via phasors in symmetrical components v a =\u221a{ square root over ( 2 )