Application of UPFC to mitigate SSR in series-compensated wind farms

Abstract

Flexible AC transmission systems have shown effective functionalities in promoting the system operation security and service reliability. Facing with series-compensated lines, subsynchronous resonance (SSR) may jeopardise the stability and mechanical facilities. The control strategy and simulation model of a unified power flow controller (UPFC) based on the dq decoupling control are deduced and constructed. Considering the impacts of grid-connected wind farms, SSR characteristics of the series-compensated system with UPFC are studied by the complex torque coefficient method and time-domain simulation. The results verify the capability of UPFC in attenuating SSR in wind farm integrations by utilising subsynchronous damping controllers coordinated with UPFC's main controllers. It also suggests that the shunt transformer−converter has a slight effect on SSR, whereas the series transformer−converter affects the system resonance characteristics significantly. Simulations are carried out on a typical power system model integrated with wind turbines.

Keywords

• power grids
• damping
• subsynchronous resonance
• power convertors
• power generation control
• wind turbines
• load flow control
• power system stability
• time-domain analysis
• wind power plants
• power transmission control
• flexible AC transmission systems
• UPFC'
• wind turbines
• system resonance characteristics
• series transformer−converter
• subsynchronous damping controllers
• wind farm integrations
• time-domain simulation
• complex torque coefficient method
• series-compensated system
• SSR characteristics
• grid-connected wind farms
• dq decoupling control
• unified power flow controller
• simulation model
• control strategy
• mechanical facilities
• subsynchronous resonance
• series-compensated lines
• service reliability
• system operation security
• effective functionalities
• flexible AC transmission systems
• series-compensated wind farms