Virtual Testing of Protection Systems using Digital Twin Technology

Abstract

Recently introduced Digital twin technology is based on the concept of a virtual device that can mimic an actual physical device to its greatest degree. Virtual testing of protection systems is made possible today using digital twin technology. A digital twin of a relay would include protection functions, algorithms, interfaces that can be validated by virtual testing, which would be equivalent to the testing of the physical relay itself. This would not only help engineers verify design and performance of an individual asset in a substation virtually but would also be able to validate the complete protection system without being in the real substation. Virtual testing includes digital twin of relay test equipment that performs a virtual injection of voltages and currents to the virtual analog inputs of the digital twin of the protection relay. The response is analyzed using the event records created in the relay or simply using the feedback from the HMI of the relay's digital twin. This is referred to as “Open Loop Testing”. Digital twin of a relay and a test set increases accessibility to a cost effective and well-rounded training which provides hands-on experience for all technicians and engineers. With the virtual set-up, costs associated with rental equipment, and travel could be eliminated. In this paper, the concept of digital twin technology, virtual testing of protection systems and the associated benefits are explained in detail. Virtual validation of protection systems using digital twin is explored with the help of testing and results. Specifically, a line distance protection relay is tested virtually using a virtual test system by using the digital twins of protection relay and of the relay test set, as well as physically by using the physical twins of the protection relay and relay test set. The results are then compared. Additionally, the paper sheds light on possible advantages of virtual testing towards commissioning and maintenance testing of protection systems.