Complementary Current Limitation Control for Grid-Forming Direct Voltage Control

Abstract

Grid-forming converter (GFC) control reproduce the behavior of a voltage source behind an impedance with retarded adjustment to change terminal complex voltage. Quite strict current limits of converter valves are conflicting requirements for the handling of fault-ride through (FRT) scenarios. The Direct Voltage Control (DVC) has been introduced as the partial and fully GFC control, which operates in d/q-coordinate. DVC is limiting the current by calculating difference voltages derived from Kirchhoff equations corresponding to high fast voltage control (FVC). In this paper, complementary current control proposes to limit the current rigidly for severe short circuits as well as angle jump, which does not perform based on voltage amplitude at the converter output. The functionality of the proposed controller is demonstrated via average EMT-type simulations under three-phase faults and grid phase/vector shifts scenarios in a transmission network test system.