From the editors' desk

Abstract

The first article in this issue is "The Effect of the Marine Environment on the Stator Insulation System of an Offshore Wind Turbine Generator" by Xuezhong Liu and colleagues from Xi’an Jiaotong University and Xiangtan Electric Manufacturing Co. Ltd., China. Compared with onshore wind farms, offshore wind farms have several advantages, e.g., the offshore wind speed is larger and more uniform, leading to greater wind power capacity and fewer turbulence effects, and, provided an offshore wind farm is located sufficiently far from the shore, visual impact, noise production, and shadow castcasting are less likely to be of public concern. However, the higher costs of foundation construction, more demanding technical requirements for wind turbine design such as anticorrosion, remote monitoring and controlling, and design considerations arising from operating in a hostile environment add to the complexity and cost. In order to simulate the influence of a marine environment on the insulation systems of a wind turbine generator (WTG), appropriate test conditions were replicated and a model stator of a 5-MW offshore WTG was tested. Testing involved temperature cycling between −30 and +100°C, maintaining constant temperature and humidity in the test chamber, and exposure to salt mist. In particular, the impact of the marine environment on the performance of the WTG insulation system was investigated by making nondestructive measurements of dissipation factor, DC insulation resistance, polarization index, and partial discharge inception voltage. These measurements were made before and after drying the specimens in an oven at 55°C for two hours. It was found that the dissipation factor and DC insulation resistance, degraded following exposure to the marine environment, recovered partially after drying.