Electromagnetic transient modeling and simulation method for internal faults in permanent magnet synchronous generators

As the key component of direct drive or semi-direct drive systems, the timely detection of internal faults in permanent magnet synchronous generators (PMSGs) is crucial for ensuring the long-term stable operation of wind turbines. Large-scale experiments are impractical for acquiring sufficient fault data, while simulations can effectively provide such data. Furthermore, the power electronic devices in wind turbines exhibit microsecond-level dynamic characteristics, necessitating electromagnetic transient (EMT) simulations. Moreover, the black-box models provided by commercial EMT simulation software do not support internal fault simulation. Additionally, existing modeling methods for PMSG internal faults can only simulate the generator itself, making it difficult to generate node-equivalent circuits and preventing direct interfacing with external components, such as converters in wind turbine systems. This paper proposes an EMT modeling and simulation method capable of representing various types of internal faults in PMSGs. By integrating two state variables, a node-equivalent circuit is developed, effectively avoiding the calculation of time-varying partial derivatives. The proposed model can directly interface with converters and grid connections, enabling the fault characteristics to be reflected in the wind turbine system. A unified EMT model encompassing multiple fault types is developed through a standardized modeling procedure. The EMT modeling and simulation are implemented in PSCAD/EMTDC and compared with results obtained from MATLAB. The results demonstrate that the proposed modeling method can accurately reflect the characteristics of internal faults, validating its effectiveness.