208 / 2018-09-16 12:34:48

Comparison Study of Voltage Error Characteristics of Three-phase Three -element Combined Transformer with Traditional and New Structure

voltage error characteristics,three-papse three element combined transformer,error characteristics simulation

The three-phase three-element combined transformer (TPTE) is widely used in the power distribution network. The traditional three-column core structure three-phase three-element (TPTE) combined transformer has electromagnetic connection, and the incomplete symmetry of the three-column core structure makes the magnetic circuit length of each phase be different from the coupling parameters. This leads to the voltage error change of each phase different, and the voltage error of each phase is even larger than the error limit. Therefore, it is of great academic significance and engineering value to study the improvement method of the voltage error performance of the TPTE combined transformer to ensure its good measurement performance under the operating condition.
A new design of three-phase three-element combined transformer with three cylindrical core was proposed, and the magnetic field distribution of voltage transformer’s core and error characteristic of voltage transformer of three-phase three-element combined transformer were obtained. The new transformer has two merits, the first is the core of voltage transformer is three-columnar with the feature of complete symmetry and stereoscopic structure, and the second is that the three current transformers are equilateral triangle arrangement and the location layout of current transformers and voltage transformers is symmetric. Through simulating analysis of magnetic field of voltage transformer’s core and error characteristic of voltage transformer of three-phase three-element combined transformer with three cylindrical core, it was discovered that magnetic field distribution of voltage transformer’s core of new transformer was more uniform, and error characteristic was better.
The magnetic induction intensity in the inner chamfer of the core of the three-phase three-element combined transformer with three-column core structure has a strong concentration phenomenon, while that in the three-column three-phase three-element combined transformer with three cylindrical core structure has a uniform distribution, so the three-phase three-element combined transformer with three cylindrical core structure has a three-phase three-element combination. The magnetic flux density distribution of the core transformer of the mutual inductor is better.
Under different loads, the error of the three-phase three-element combined transformer with three cylindrical core structure changes more smoothly with the increase of voltage, and the error difference between the phases is smaller. The error characteristics of the new three-phase three-element combined transformer with three cylindrical core are better than those of the traditional three-phase three-element combined transformer with three-column core structure. In the case of unbalanced primary load and secondary load, the three-phase three-element combined transformer with three-cylinder core structure has better error characteristics. The research results of this paper provide valuable reference for accurately grasping and improving the error characteristics of three-phase three-element combined transformer under operating conditions.