Intelligent protection of multiterminal VSC-HVDC systems: aspects of simulation and implementation

Abstract

The high short-circuit currents Voltage Source Converters (VSCs) which also have a rapid rise rate, are still a challenge for High Voltage Direct Current (HVDC) multiterminal systems reliability. As soon as a fault starts in an HVDC grid, large over currents have to be rapidly detected and interrupted by breakers. However, it is not straightforward to locate the point of occurrence of a fault due to multiple current paths. Several algorithms were proposed for multiterminal VSC-HVDC grids, however, there is still a lack of techniques that selectively identify the short-circuited branch in the timescale needed in the VSC context. Thus, the present proposal proposes developing and implementing signal processing and intelligent algorithms for VSC-HVDC system protection, as they emerge as possible improvements for existing techniques. In order to develop a protection algorithm for multiterminal VSC-HVDC systems, the proposed methodology consists of simulations of several types of faults in a fourterminal symmetric monopolar VSC-HVDC system comprising Modular Multilevel Converters (MMCs), with posterior fault and algorithm-improvement analysis in software such as Matlabor Python. The final expected result is a protection algorithm which can identify the faulted portion of the multiterminal system within the timescale need in VSC-HVDC systems. (AU)