Hardware-in-the-loop simulation applied to protection devices testing

Abstract

Circuit breakers are ubiquitous elements used for ensuring safe operation of low-voltage power systems. Nowadays the loads supplied by the power systems migrate towards exhibiting significant strong nonlinear behavior accompanied by inrush currents or high-order harmonics that can cause a false tripping of circuit breakers. It is thus necessary to study the interaction between these new loads and the protection devices in order to fully assess their compatibility. Following this context, this paper deals with a new test rig dedicated to protection switching devices, which is based on the hardware-in-the-loop real-time simulation concept. The proposed approach is focused on replicating the tripping conditions of a real circuit breaker coupled to a power system emulated by means of a real-time simulator. The software part of this simulator adds flexibility to the test rig as the circuit configurations and the operating scenarios may conveniently be adapted at lowest cost. The control of the interface between the software simulator and the hardware under test, as well as the closed-loop stability issues, has been thoroughly approached. Experiments carried out on this test rig show the effectiveness of this new test prototyping concept in characterizing real circuit breakers behavior when they protect lighting circuits.