On Control of Grid-connected Voltage Source Converters - Mitigation of Voltage Dips and Subsynchronous Resonances

摘要: Custom Power and Flexible AC Transmission Systems (FACTS) denote the application of power electronics in distribution transmission networks, respectively. is to improve quality for sensitive industrial plants. electronic converters connected shunt or series with grid equipped energy storage can provide protection processes against voltage disturbances, like short interruptions dips. The first part this thesis focuses on control Voltage Source Converter (VSC) mitigation In both configurations, core system current controller. Here, deadbeat controller grid-connected VSC presented analyzed detail. includes time delay compensation reference limitation feedback, during overmodulation. Improvements proper under unbalanced conditions are investigated. For use a series-connected VSC, completed an outer loop, thus realizing cascade that Further, similar dip using shunt-connected it shown negative-sequence component injected needed FACTS instead at level. systems, other objectives more important than compensation. Controllable used e.g. flow control, stability improvement, damping oscillations. Traditional non-controllable based capacitors create problems due unwanted resonance rest system. A specific problem often arises conjunction subsynchronous (SSR), which lead damage generator shafts. case, one here called Static Synchronous Series Compensator (SSSC), could be as dedicated device SSR mitigation. second thesis, novel strategy SSSC investigated analyzed. It that, by injecting only into system, achieved increasing network those frequencies danger generator-shaft This will allow very low injection, leading cost-effective alternative existing solutions.