Voltage source control of offshore all-DC wind farm

Abstract

The fast growth of offshore all-DC wind farm will bring problems such as the weakening of grid frequency stability and the increase of equivalent grid impedance. To overcome this, a coordination control strategy for offshore all-DC wind farm is proposed in this study with two salient features: better performance under weak grid condition, and real-time frequency support from wind farm. This strategy consists of three parts: the inertia synchronising control of receiving end converter, the constant ratio control of DC transformer and the frequency response of wind farm. With the proposed strategy, the all-DC wind farm operates like a synchronous generator to onshore grid, which provides fast frequency support when the onshore grid frequency changes. The effectiveness of the proposed method is validated in PSCAD/EMTDC.

Keywords

• offshore installations
• frequency control
• power generation control
• synchronous generators
• frequency response
• wind power plants
• power grids
• all-dc wind farm
• grid frequency stability
• coordination control strategy
• onshore grid frequency changes
• voltage source control
• constant ratio control
• dc transformer
• inertia synchronising control
• weak grid condition