Voltage source control of offshore all‐DC wind farm

Abstract

The offshore all-DC wind farm with increasing capacity will bring problems such as the weakening of grid frequency stability and the increase of equivalent grid impedance. To overcome this, a coordinated control strategy for the offshore all-DC wind farm is proposed here with two salient features: better performance under weak grid condition and real-time frequency support from the wind farm. The control strategy consists of three parts: the inertia synchronising control of the receiving-end converter, the constant ratio control of the DC transformer and the frequency response of the wind farm. With the proposed strategy, the all-DC wind farm operates like a synchronous generator to the onshore grid, which provides fast frequency support when the onshore grid frequency changes. The effectiveness of the proposed method is validated in power systems computer aided design (PSCAD)/electromagnetic transients including DC (EMTDC) using a typical IEEE 9 bus system.

Wind turbine multiphase operational trajectory in an all‐DC wind generation system

“…The system proposed by Yang et al [14] follows a similar WTG to that of Fig. 1 c , however, the authors in [14] discuss a general overview and do not provide details on the WTG model, DC/DC converter topology, its control or operation.…”

“…The system proposed by Yang et al [14] follows a similar WTG to that of Fig. 1 c , however, the authors in [14] discuss a general overview and do not provide details on the WTG model, DC/DC converter topology, its control or operation. The authors in [9] provide a general topological overview of different approaches for an all‐DC grid that uses a similar WTG to Fig.…”

“…Studies aim to introduce the DC system for both collector and transmission grids, making a wind farm an all‐DC system [9–14]. A control system for a parallel DC interconnection system is proposed by Meyer et al [9] that is claimed to be economical for off‐shore wind power.…”

“…Studies aim to introduce the DC system for both collector and transmission grids, making a wind farm an all-DC system [9][10][11][12][13][14].…”

“…Steady-state and fault analysis of a wind farm with a medium-voltage DC (MVDC) collector grid and an HVDC transmission is addressed in [13]. A coordinated control approach for a wind farm with DC collector HVDC transmission grids is presented in [14], where from the AC grid point of view, the wind farm acts as a synchronous generator (SG).…”