The Results of the Study on Relay Protection of Power Transmission Lines from Wind and Solar Power Plants

National Electric Grid of the Russian Federation were selected as the renewable energy generation facilities to be simulated: wind power plant based on a Type 4 wind turbine, wind power plant based on a Type 3 wind turbine, and a solar power plant. It was established that the main protection function most suited to the influence of inverter based resources is line differential protection, but in a number of experiments, a delayed tripping of this protection was recorded. The functions of phase comparison protection of lines and directional high-frequency protection of lines operate incorrectly in a significant part of the experiments. Incorrect behaviour is observed mainly in the case of feeding the fault location only from an inverter based resource. Of the backup protections functions, the directional neutral current protection function is the most adapted to the characteristics of transient processes in inverter based resource if a negative sequence power direction measuring device is not used. However, in the case of a low zero-sequence current feeding the fault location from a solar or wind power plant, the function may also malfunction. The distance protection function malfunctions in a significant number of tests. To ensure the correct operation of relay protection functions, a comprehensive solution is required, consisting of modelling the operation of a renewable energy generation facility and the external network adjacent to the facility using the relay protection devices and settings specified in the design solutions, as well as inverter based resource and their control algorithm settings, which will allow for the early detection of modes in which the operation of relay protection functions is disrupted. In addition to this approach, requirements for inverter based resources should be developed in terms of current formation in short-circuit modes.