Transient Analysis of LCC based HVDC Offshore Wind Farms using DIgSILENT PowerFactory

Abstract

Offshore wind farms (OWFs) connect to onshore grids through HVDC cable. Severe grid faults mainly affect the offshore wind farms and HVDC cables. As a result, the transient response of the system deteriorates. Therefore, this paper aims for the transient analysis of line commutated current converter (LCC) based HVDC system under 3-phase fault. The paper proposes the DIgSILENT Simulation Language (DSL) oriented PI control for the both rectifier and inverter stations. The whole HVDC system is modelled in DIgSILENT PowerFactory software for the better transient response. In addition, the PI control and voltage dependent current order limiter (VDCOL) are designed in this PowerFactory software. The advantage of this software is that it improves the transient behaviour and stability of the system. These controllers limit the inrush current and voltage fluctuations at the moment of fault occurrence and clearance. The simulation results under fault indicate the better transient response with the system stability.