Abstract
Grid codes specify how WTGs (wind turbine generators) should respond to voltage dips occurring due to grid faults, with specific requirements varying from country to country. The standard IEC 61400-21 suggests a method for testing the WTG response to voltage drops, which has been used as a basis for the work described in this project memo. The method uses a set-up with a series and a shunt impedance to create a voltage dip on the WTG terminals. IEC 61400-21 specifies a voltage magnitude versus time curve for WTG response testing. Grid codes specify FRT (fault ride-through) requirements with the same type of curves. The question to be investigated in this work was if the voltage phase angle change occurring during a voltage dip has an impact on the WTG active and reactive power responses. In that case, should the voltage phase angle change be specified in addition to the voltage magnitude-versus-time curve?
Simulation results show that the active power responses of fixed speed WTGs depend on both changes in grid voltage magnitude and phase angle, especially at low power production level. This means that phase angle change cannot be neglected. For full-power converter interfaced WTGs the active and reactive power responses of are determined by the converter controller and implemented control strategies.
Simulation results show that the active power responses of fixed speed WTGs depend on both changes in grid voltage magnitude and phase angle, especially at low power production level. This means that phase angle change cannot be neglected. For full-power converter interfaced WTGs the active and reactive power responses of are determined by the converter controller and implemented control strategies.