Fault ride through during loss of converter in a 4-VSC based HVDC transmission

Abstract

Abstract-VSC based Multi-terminal HVDC transmission is employed for the integration of offshore wind and wave farms. Flexibility, reliability and reduced transmission losses are the main/primary reasons for preference of MTDC networks. The transmission layout still suffers from some drawbacks, of which the most prominent is fault ride through capability in terms of its response to either a temporal or permanent loss of converter station(s). This paper presents the simulation analysis of hysteresis based and PI-based DC grid voltage control techniques for fault ride through capability of a 4 terminal HVDC network (MTDC), which consisted of a wind farm, wave farm and two onshore converters. The analysis showed that the PI method resulted in a faster response time as well as smaller overshoots and dips when a three phase to ground fault occurs. A detailed electromagnetic transient (EMT) study was performed using MATLAB/Simulink. Index Terms--Fault ride through (FRT), Hysteresis controller, PI controller, VSC HVDC, MTDC.

Positive-Negative Sequence Current Controller for LVRT Improvement of Wind Farms Integrated MMC-HVDC Network

“…As the balanced fault does not contain negative sequence voltage, negative sequence reactive current has not been generated. Positive sequence real and reactive current are generated from the HVDC link voltage regulation and positive sequence reactive current as presented in (24) and (21) respectively. Since the negative sequence current injection is zero, no oscillation is introduced in the current limiting positive sequence dq-frame.…”

“…However, this approach keeps a large number of semiconductor switches turned on at normal operating conditions, resulting in continuous conduction loss. As the wind generator has high inertia, it cannot change output abruptly during the transient fault, which has led the placement of a dynamic braking resistor to mitigate the excess energy in the HVDC link [21], [22]. Besides second-order oscillation and DC link voltage protection, over current protection is the most critical for the converter.…”

Active distribution power system with multi‐terminal DC links

“…As the current can always be well controlled within a predefined limit, the overvoltage will not damage the switching device as long as it is below a certain voltage level (normally at a maximum of 140% for 1.2 kV systems [26]). Practically, the transient overvoltage can be further well capped by dumping resistances if it is above a predefined voltage level [27]; the terminal transient power can therefore be capped regardless of the initial power input. Since the transient is very short, the total energy is limited.…”

DC Soft Open Points for Resilient and Reconfigurable DC Distribution Networks

“…The control of multi-terminal DC systems can be more difficult than their AC counterparts, precisely due to the lack of reactive power capability. This becomes especially important during disturbances [11].…”