This paper reports a new project - the poloidal field (PF) grid power supply systemto replace the ac flywheel generator power supply system on the basis of the present runningparameters of the HT-7 poloidal field and the short-circuit capacity of our transformer substation.The designed parameters of the PF grid power supply system have been verified to meet therequirements of the heating field (HF) and the vertical field (VF). In the meantime, in order toreduce the disturbance to the local power grid, the device of reactive power and harmonic currentcompensation has been added. Experimental results have confirmed the feasibility of the PF gridpower supply system. Compared with the ac flywheel generator, the PF grid power supply systemhas the advantages of lower noise, precise control, convenient maintenance, simple operation andcost savings. This paper reports a new project - the poloidal field (PF) grid power supply system to replace the ac flywheel generator power supply system on the basis of the present running pararameters of the HT-7 poloidal field and the short-circuit capacity of our transformer substation. The designed parameters of the PF grid power supply system have been verified to meet therequirements of the heating field (HF) and the vertical field (VF). In the meantime, in order toreduce the disturbance to the local power grid, the device of reactive Compared with the ac flywheel generator, the PF grid power supply system has the advantages of lower noise, precise control, convenient maintenance, simple operation and cost savings .