High-Precision Wide-Range Current Transformer Based on Compensation Algorithm

Current transformers (CTs) are critical devices in power systems, and their measurement accuracy directly affects the safety and stability of the power grid. This paper proposes a compensation algorithm for CTs to enhance measurement precision effectively. Firstly, offline measurements of the primary and secondary side currents and the magnetic flux of the CT under different operational conditions are conducted. A model of the magnetic flux versus excitation current curve is fitted from this. With the help of this fitted model, during online measurements, the excitation current is obtained from the magnetic flux, which is then used to compensate for the secondary current. To verify the performance of the proposed method, this paper conducted validations through simulations and physical experiments. In EMTP-RV, simulations were conducted based on the data from actual 10P10-rated protection CTs, choosing several known and unknown operating conditions. A physical experimental platform was set up for compensation experiments on closed and open-type 10P10 protection CTs. Both simulation and physical experimental results indicate that the proposed method can effectively enhance the measurement accuracy of wide-range CTs, validating the feasibility of high-precision wide-range CTs.