The short circuit of the AC transmission line of the MMC-HVDC transmission connected with Wind-PV-Thermal-Energy storage system will generate new fault characteristics. Combining the fault ride-through control strategies, the mechanism of the controlled phase angle of the current on both sides of the AC line at the sending end during a fault in this situation are analyzed. The research results show that when the AC transmission line fault happens, both the Wind-PV-Thermal-Energy storage system side and MMC side will inject reactive power into the AC system under control strategies to prevent further voltage drop in the AC system. The variation range of the phase angle of the fault currents on the wind, PV and energy storage system and MMC is affected by the voltage drop level and the upper limit of the amplitude limiting link. When the voltage drop level is within 0.9 p.u. to 0.2 p.u., the variation range of the phase angle on the Wind-PV-Thermal-Energy storage system side is less than 60° or 75°, and that on the MMC side is less than 45°. Finally, the effectiveness of the control strategy for fault ride-through is verified through RTDS simulation experiments, proving the consistency of theoretical analysis conclusions and simulation experiments under this strategy.