Protection of an HVDC Link Towards Modeling and Simulation Based DC Connection Defects

Abstract

This paper aims to study the DC-link faults and recovery scenarios based on a 12-pulse HVDC (High Voltage Direct Current) link system. DC-link to ground fault is considered as one of the most serious fault that can occur on HVDC-link. Therefore, in order to understand the system behavior in the presence of this type of fault, two DC-fault scenarios are investigated. One scenario is at the sending end of the rectifier, and the other is at the receiving end of the inverter. The faults are applied mainly to study the dynamic performance of the recovery of HVDC-link system after faults, and to validate the proposed DC fault protection function. Influence of the Voltage Dependent Current Order Limiter (VDCOL) function is also studied. The digital real-time simulator laboratory (RT-Lab) platform HYPERSIM (OP-5600) is used in modeling and simulation of the HVDC-link system by means of Software-In-the-Loop (SIL) approach. The maintenance of the system stability is investigated to ensure a high performance recovery from the fault. Ramp-up recovery method used in the DCbus voltage restoration provided by the VDCOL-function, and the validated operation of protection function against DC faults show high performance recovery from the faults. The results carried out ensure safe and desired recovery from the DC-bus faults.