Automation of cycles of protections’ non-traditional tests using traditional injectors and electromagnetic transient programs via Python

This article shows a method to perform cycles of non-traditional tests to electric power system protections, in an automated way, using traditional injectors and Electro-Magnetic Transient Software (EMTS) via Python. Non-traditional tests of protective relays, using non-sinusoidal current and voltage waveforms computed from an EMTS, have been performed since the invention of programmable injectors but different non-obvious steps are necessary for this purpose (the obtained files from the EMTS must be converted to a standardized format to be transferred to the injector, injected to the relay under test, and the relay contacts have to be monitored in order to record their operation or non-operation, and/or to record their operation time). In order to easily perform repetitive cycles of these non-traditional tests, with different conditions of simulation in the EMTS, these steps were automated using Python, which is simply applied to control the injector and the EMTS in a loop. This method is suitable for different practical cases, and it is useful to avoid some costs and disadvantages related to the use of real-time simulation (which probably is the most known alternative to perform these cycles of tests). Herein, the obtainment of tripping times of distance protections as a function of fault location and source impedance in case of a series-compensated line is shown as an example. The results were obtained for mho and quadrilateral characteristics of three commercial relays, using a very basic injector and a royalty-free EMTS in order to illustrate that the tests can be performed with very low resources. The proposed method is considerably less expensive than the use of real-time digital simulators, and considerably faster than the use of the same resources without the proposed automation, which currently are the main available methods for these tests.