Challenges on Field Testing a Tidal Power Plant to Achieve IEC Conformity - Sihwa Tidal in South Korea

The paper deals with the difficulties and differences in measuring the efficiency in a tidal power plant compared to a standard power plant with special focus on the world's largest tidal power plant Sihwa Tidal in South Korea. Firstly the difficulties to achieve IEC 60041-1991 conformity in such a case will be pointed out. Secondly the difficulties of placing the measurement equipment will be highlighted. The first topic arises mainly from the tides. The nature of rising and falling of the sea level induced by the ebb and the flood avoids long periods of constant water levels and this makes it difficult to stay within the IEC 60041-1991 ranges. The second challenge is more an issue due to the sea itself. Waves make it necessary to take longer readings for each measurement point to obtain proper data and therefore avoid a fast measuring sequence as it would conclude out of the tide problem. Another issue is the inflow. In a river the flow direction towards the intake is mostly known and constant. Unlike river power plants tidal power plants do not have this advantage. The angle of the water is depending on several different parameters. It is influenced by the rising or falling of the tide, the hydraulic contour in the wider area in front of the power plant and last but not least on the wind. As a consequence, the correct position of the measuring taps has to be considered both for height measurement and differential pressure measurement as used for the flow indication. To obtain an idea of the relation between the flow angle and the measuring uncertainty a detailed CFD investigation was done and will be presented in this paper. Finally some comments on maritime life and the effect on efficiency and power output are discussed.