The use of full size power converter for direct-drive wind turbines has an impact on the power quality of grid. This paper presented the configuration of two types of 1.5MW permanent magnet direct drive grid-connected wind turbines. The topologies and control strategies of converter I and converter II system are also compared. According to IEC measurement methods, the emission levels and characteristics of current harmonics, interharmonics and higher frequency components are measured and studied in field tests. The test results show that the emissions of current harmonics is in compliance with the grid code requirements, and the current harmonics level of wind turbine with converter I is 2.52% lower than 3.44% of wind turbine with converter II.