Multiple Transient Stress Analysis for Energy Storage AC Excitation Condenser Under Grid Faults

The access of new energy on a large scale promotes the power electrification process of the power grid and intensifies the system stability challenges. Energy Storage AC Excited Condenser (ESAEC) has become a key device for active support of new energy grid by virtue of its wide turndown range and strong support capability. However, its converter capacity limitation and magnetic circuit strong coupling characteristics are complex, and it is prone to multiple stress overruns during grid faults, such as rotor current, electromagnetic torque and DC bus voltage. This paper establishes a multi-stress analytical model of ESAEC under grid fault, and reveals the evolution laws of rotor current, electromagnetic torque and DC bus voltage. The effects of stator-rotor leakage inductance, depth of voltage dips, and slip rate on different stresses are revealed. The stress characteristics under voltage dip and frequency dip conditions are compared, which provides a theoretical basis for optimizing the transient stress suppression strategy of ESAEC and improving the fault ride-through capability of the power grid.