Coordinated Low Frequency Oscillation Damping Method for Hydropower System with Photovoltaic Units and Static Var Generators

This paper investigates the coordination control strategy to damp the low frequency oscilaltions (LFO) in hydropower system, where the photovoltaic units (PV) and static var generators (SVG) are considered. To clarify the dynamic interaction mechanism of the PV and SVG in LFO problem, the complex torque coefficient method is used when the control method is designed. Based on the above theory, it is found that the PV and SVG can influence the damping torque intensively, such that the LFO can be suppressed by the designed controllers added in PV and SVG devices. Nevertheless, make the designed controllers coordinated with each other, the improved plant growth simulation algorithm (PGSA) is also proposed to further increase the damping ratio of the system, which can also avoid the instabilities cause by impropriate parameter settings. Finally, the simulations are implemented in electromechanical transient software PSASP and validate the correctness and effectiveness of the proposed method.