Voltage and Transient Stability Support by Wind Farms Complying With the E.ON Netz Grid Code

In this paper, the impact of the response of a wind farm (WF) on the operation of a nearby grid is investigated during network disturbances. Only modern variable speed wind turbines are treated in this work. The new E.ON Netz fault response code for WF is taken as the base case for the study. The results found in this paper are that the performance of the used Cigre 32-bus test system during disturbances is improved when the WF is complying with the E.ON code compared to the traditional unity power factor operation. Further improvements are found when the slope of the reactive current support line is increased from the E.ON specified value. In addition, a larger converter of a variable speed wind turbine is exploited that is to be used in order to improve the stability of a nearby grid by extending the reactive current support. By doing so, it is shown in this paper that the voltage profile at the point of common coupling (pcc) as well as the transient stability of the grid are improved compared to the original E.ON code, in addition to the improvements already achieved by using the E.ON code in its original form. Finally, regarding the utilization of a larger converter, it is important to point out that the possible reactive power in-feed into the pcc from an offshore WF decreases with increasing cable length during network faults, making it difficult to support the grid with extra reactive power during disturbances.