Impact of Active Power Curtailment of Wind Turbines Connected to Residential Feeders for Overvoltage Prevention

Overvoltage is a major limiting factor for the integration of distributed generation in distribution systems. Among various solutions to the overvoltage problem, active power curtailment is an attractive solution since only small adjustments in the controllers are necessary for implementing this technique. Furthermore, it is activated only when needed. In wind energy systems, this can be achieved by adjusting the pitch angle of a wind turbine. The objective of this paper is to develop an active power curtailment strategy for small wind turbines to prevent overvoltage by controlling the pitch angle of the turbine blades. The required blade pitch angle was calculated by using the voltage droop method. The developed control strategy was validated by a real time simulation of a rural feeder model developed using RT-Lab software. The feeder is based upon a North American rural distribution network consisting of 96 small wind turbines of 20 kW, a 30 MVA distribution substation with an on-load tap-changing transformer, a rural feeder with 288 houses, a 120 kV/25 kV LV transformer, and rural loads. The results show the effectiveness of the method in keeping the voltage within acceptable limits and a reduction in network losses.