Optimization of short-circuit tests based on finite element analysis

One of the main problems that arises when performing short-circuit tests to large loops involving substation connectors is the inductive component of the loop impedance. Transformers used to perform short-circuit tests have a secondary winding with very few turns, producing a very low output voltage. The increase in the reactive component of the impedance, which is related to loop size, limits the current output capacity, because the reactive component tends to saturate the output of the transformer and absorbs large amounts of reactive power. This paper analyzes a simple method to minimize the power requirements when conducting short-circuit tests, based on the reduction of reactive power consumption during the test. It is based on placing a wired conductor forming a closed inner loop concentric with the testing loop. The decrease of reactive power is related to the effect of the mutual inductance between the inner and outer loops. Three-dimensional finite element method (3D-FEM) simulations are used to optimize the problem, allowing changing the geometric and material properties of the inner loop. Experimental results validate the simulation method applied in this work to optimize the short-circuit tests.