The energy transition – i.e. the generation of electricity from renewable energy – is setting major challenges for energy suppliers, grid operators and system manufacturers. The large and still growing contribution of wind power to electricity generation, in particular, means that the technical requirements have to be very exacting, if a reliable energy supply is to be guaranteed.
In the development of wind turbines, manufacturers have gained a lot of experience in testing the individual components. The trialling and testing of wind turbines as a system is becoming ever more complex; firstly, because system output is continually increasing, and secondly, because the technical certification guidelines are becoming more and more exhaustive.
In order to certify the electrical characteristics of wind turbines in field tests or system test benches in accordance with the Technical Guideline TR3  of the Federation of German Windpower and other Renewable Energies (FGW e.V.), a precise measurement system with highly efficient mathematical analysis is needed. In this report, we present and explain mathematical methods aimed at describing and evaluating the behavior of wind turbines at the grid feed-in point.