In order to meet the needs of building a new type of power system under China's "dual-carbon" strategy

for the new energy grid-connected many problems affecting the accuracy of power metering

by analyzing the current transformer error and the amount of influence

we propose the design of multiple micro air gap composite cores

which are designed through the equivalent circuit

the determination of the air gap

the selection of the core material and other aspects and verified by simulation. Tests on the designed HL(D)-500/5 current transformer show that its accuracy reaches 0.2SS level in the range of 0.1% to 200% In at the industrial frequency

and 0.2 level when superimposed with 10% DC component

which meets the metering requirements of the new type of electric power system in a wide dynamic range and with DC component.