Effect of the transmission configuration of wind farms on their capacity factors

This study conducted a feasibility study to analyze and improve the operational performance of two current onshore wind farms on the Changhua coastal area in Taiwan. We selected two adjacent wind farms A and B with similar wind-power density and geographical conditions; whereas, their main differences were the material of cables, the type of transformers, the number of cable branches, and the depth of buried cables. In actual operation states, the wind farm A had greater capacity factor than the wind farm B; therefore, the wind farm A was regarded as a base case, and two new wind farms 1B and 2B, resulting from the changes in the cable materials, transformer types, cable branches, and buried cable depth of the wind farm B, were proposed to assess the feasibility of system improvement. Results showed that the material of cables, the type of transformers, the number of cable branches, and the depth of buried cables were the crucial factors of affecting the efficiency of wind farm B. Shallow cabling increased the temperature of cables, higher temperature causing a decline in cable capacity, and this phenomenon was crucial to aluminum cables rather than copper cables. The results of comparing the wind farms 2B with B indicated that the maximal transmission loss of cables was reduced by 6.4 GW h/year, and the maximal annual CO2 emission was reduced by 4.5 kt/year. Additionally, the increased cost of transformers and cabling was recovered in 2.12 years, when the wind farm B was modified to 2B before construction.