ENHANCEMENT OF FREQUENCY SUPPORT CAPABILITIES OF TYPE 1 AND TYPE 2 WIND TURBINES

Electricity production in remote communities in northern Quebec is still largely based on diesel power supply. Environmental concerns and the cost of electricity are driving the integration of wind energy in such systems. However, due to the stochastic nature of the wind and the highly variable load characteristic in these communities, the displacement of diesel fuel is usually small. In addition to this, when the system operates with high wind penetration, the frequency tends to vary widely, thereby raising some important stability concerns. This research work investigates important technical issues related to the implementation of fixed-pitch wind turbines that present large droop factor in droop-controlled hybrid diesel mini-grids, to enhance the frequency regulation. An assessment of generators for small scale generation is first presented. Next, a concept for implementing a fixed speed (type 1) wind turbine in a hybrid system is developed, using the power-frequency characteristic of the wind turbine. Due to some limitations of the proposed concept, resulting mainly from the fact that wind turbine power-frequency characteristics present a relatively low droop factor, type 1 wind turbines cannot assist to a high extent with the network frequency regulation. Therefore an approach to implement type 2 wind turbines which present a better droop factor has been developed and used to overcome the limitations of the type 1 system. A hybrid wind diesel mini-grid model without storage has been developed and used to validate the analysis. The proposed implementation concepts provide several benefits for the electrification of remote communities, which are highlighted at different stages of the thesis