Backup Source for Yaw Control System of Wind Farms by Reverse Power Transmission

Yaw control system is an important part of the wind turbine located in the typhoon-covered areas. It can reduce the ultimate load and fatigue load of the typhoons. Back-up power source is the foundation to ensure the normal operation of the yaw control system. This paper first explains different back-up source configurations and gives a detailed study on the centralized diesel generator configured in the set-up substation. A reverse power transmission test program is designed. The voltage and its spectrum of the bus are monitored. The harmonics problem is studied and the results indicate that the capacitance effect of the transmission cables can amplify the harmonic components of the exciting current of the transformer. Both theoretical analysis and simulation test are given to explain the cause of harmonics in the voltage. At last, an improved suggestion and countmeasure is provided.