Active Thermal Control-Based Anticondensation Strategy in Paralleled Wind Power Converters by Adjusting Reactive Circulating Current

Offshore wind power converters are usually installed in a closed cabinet equipped with water cooling to meet the moisture and salt spray prevention requirements. When the system faces a sudden dip in the wind speed and is subject to a drastic decline in the output power level, the temperatures of the power semiconductors and cooling water drop immediately. Since the temperature of air inside the cabinet decreases at a much slower rate, the heatsink, water-cooling panels, and water pipes become potential cold spots in the closed space. In this situation, condensation occurs if the temperature of the cold spots drops below the dew point; and the dew formed on these surfaces may damage the electrical and mechanical parts and components, and even result in failure of the entire converter unit. In this paper, an effective active thermal control-based anticondensation strategy by adjusting reactive circulating current is proposed for high-power paralleled wind power converters. By taking advantage of the reactive circulating power control, that is, integral to such configurations, the temperature of the potential cold spots is always maintained above the dew point. Hence, anticondensation is achieved without taking costly extra measures such as external air conditioning or dehumidification. The modeling and theoretical analyses are elaborated for the proposed method, which is verified by simulation and experiment results obtained on a 3-MW wind power system.