The HY-PSP-A Series programmable three-phase phase-shift AC power source is a high-precision three-phase standard source developed by Hangyu Power Shanghai for power metrology industries. It supports dual operation modes: mains synchronization and independent variable frequency. The three-phase voltage, inter-phase angle, input-output phase difference, and voltage-current phase shift can all be steplessly adjusted separately with 0.01° phase resolution, accurately simulating unbalanced and offset grid operating conditions.