Testing distributed protection systems over the Internet cloud

Due to the increasing complexity of our electrical power systems, the need for highly selective protection is increasingly being fulfilled by the use of teleprotection schemes or line differential protection. To test such distributed protection systems properly, a distributed end-to-end test with synchronized injection is required. The first challenge for such a test is the correct calculation of the voltages and currents to inject at both (or even multiple) ends. Therefore, a simulation of the fault scenario based on the power system network, is needed which can deliver all of the required values. For the execution of an actual fault scenario (shot), a single software application which controls all test devices on both (or multiple) ends from a single PC, is much more convenient and productive than separate software applications, which have to be operated manually for synchronized injection. To synchronize the injected voltages and currents for all ends mostly GPS time sources are used. GPS time sources, which can deliver accurate time over a network connection via IEEE 1588 PTP (Precision Time Protocol), need just to be plugged into the test devices and can even bridge long distances from outside into the substations. Controlling a remote test device is nowadays possible using an Internet connection at each end of the test, e.g. leveraging existing Internet access of mobile phones. Therefore a service in the Internet cloud can be used to identify and connect the remote partners and avoid complex setup of network tunnels.