A benchmark study on the AC voltage in the 3L converter for high power offshore wind turbines

Abstract:
This paper introduces the latest trends in power converters in offshore wind turbines and analyses the influence of different interconnection grid voltages. A benchmark analysis was performed using three types of IGBT modules for various grid voltage classes that are compatible with the same mechanical design, in a unified converter cabinet. A detailed simulation model was also built including package equivalent resistance that can help get more accurate power loss, system efficiency and temperature rise. These benchmark results are more meaningful in real system designs. An 1800 Vac is proposed as the new grid interconnection voltage in this paper. It can be realized with the latest 2300 V IGBT half-bridge module in a neutral point clamped three-level topology. This voltage class shows a lot of benefits in improving power losses and system efficiency. It also increases power density and reduces system costs.