In order to reliably verify the current transformers, it is generally required that the verification system maintains a high output accuracy within a wide capacity range of 5% to 110%.In order to solve the problem of the low accuracy of the output of the ultra-high voltage gas-insulated enclosed combined electrical type (GIS) current transformer calibration system in a wide range of output. A combination of digital, high-capacity, wide-voltage, and high-precision power solutions is proposed.The scheme uses a combined power supply structure in series with a power electronic power supply and an electrical power supply. The electrical power supply regulates the voltage output through a voltage regulator,used when combining power supply low voltage output.Power electronic power supply adopts single-phase full-bridge inverter structure.When the combined power supply outputs a large voltage, the combined power supply in series can maintain high accuracy over a wide range of voltage output. In order to make the electronic power source and electrical power maintain synchronous operation, a frequency adaptive proportional resonant (PR) controller is used. Added frequency adjustment module based on adaptive notch filter on the basis of traditional PR controller .The PR controller parameters of power electronics are designed as time-varying parameters according to the frequency of electrician power. Then, the frequency and phase of electrician power supply are tracked in real time by adaptive notch filter. The experimental results show that the frequency adaptive PR controller can make the power electronic power supply output high-precision voltage waveform, and synchronise with the electric power supply's frequency and phase at any time, and the output voltage of the combined power supply is stable and THD<3%.