A review of common-mode voltage suppression methods in wind power generation

As one of the most efficient and advantageous sources of renewable energy, wind energy is being developed and utilized at an expansive scale. The increase in installed capacity and the trend toward high-power wind turbines highlight the impacts of common-mode voltage (CMV), because CMV induces high-frequency electromagnetic interference (EMI) noise and destructive bearing currents through paths consisting of parasitic and coupling parameters. This review briefly introduces how CMV causes damages to wind power generation system, and then introduces CMV suppression strategies, including hardware-based and software-based methods. Three typical hardware-based methods are reviewed, including enhancing the components or structure of the generator, adding common-mode filters to the electric circuits, and changing the power converter topologies. These methods can effectively reduce CMV but introduce challenges such as demanding routine maintenance, and hardware redesigns. Software-based methods reviewed are mainly the modified pulse width modulation (PWM) schemes for the both the conventional three-phase two-level converters and the multilevel or multiphase converters. They actively suppress the source of CMV and have good cost-effectiveness. For example, a modified carrier-based PWM method can reduce the CMV root mean square value by more than 90 %. Pros and cons of all the reviewed CMV suppression methods are presented, which helps the readers to identify the most suitable solutions for practical applications. In general, it is recommended to adopt electrically insulated bearings, hybrid filters, multilevel converters, modified carrier-based PWM methods to compose the best wind power generation system in terms of the CMV performance.