Thyge Knüppel

Power oscillation damping controller for wind power plant utilizing wind turbine inertia as energy storage

For a wind power plant (WPP) the upper limit for active power output is bounded by the instantaneous wind conditions and therefore a WPP must curtail its power output when system services with active power are delivered. Here, a power oscillation damping controller (POD) for WPPs is presented that utilizes the stored kinetic energy in the wind turbine (WT) mechanical system as energy storage from which damping power can be exchanged. This eliminates the need for curtailed active power production. Results are presented using modal analysis and induced torque coefficients (ITC) to depict the torques induced on the synchronous generators from the POD. These are supplemented with nonlinear time domain simulations with and without an auxiliary POD for the WPP. The work is based on a nonlinear, dynamic model of the 3.6 MW Siemens Wind Power wind turbine.

Residue-Based Evaluation of the Use of Wind Power Plants With Full Converter Wind Turbines for Power Oscillation Damping Control

As wind power plants (WPPs) gradually replace the power production of the conventional generators, many aspects of the power system may be affected, in which the small signal stability is included. Additional control may be needed for wind turbine generators (WTGs) to participate in the power oscillation damping. The feasibility of implementing this control needs to be assessed. This paper studies how the damping contribution of a WPP is affected by different operating conditions and its dependence to selected feedback signals. The WPP model used includes individual WTGs to study how internal changes may affect this contribution. The study is based on the changes suffered by the residues of the electromechanical modes, which indicate the sensitivity of the modes to this particular feedback. The results show that a park level control for the entire WPP is possible, although it may not provide damping for a range of critical operating conditions.

Towards a reactive power oscillation damping controller for wind power plant based on full converter wind turbines

In this paper a power oscillation damping controller (POD) based on modulation of reactive power (ΔQ POD) is analyzed where the modular and distributed characteristics of the wind power plant (WPP) are considered. For a ΔQ POD it is essential that the phase of the modulated output is tightly controlled to achieve a positive damping contribution. It is investigated how a park level voltage, reactive power, and power factor control at different grid strengths interact with the ΔQ POD in terms of a resulting phase shift. A WPP is modular and distributed and a WPP ΔQ POD necessitate that each WT contributes to a collective response. This ability is shown with a 150 wind turbine (WT) WPP with all WTs represented, and it is demonstrated that the WPP contributes to the inter-area damping. The work is based on a nonlinear, dynamic model of the 3.6 MW Siemens Wind Power WT.

Using H ∞ to design robust POD controllers for wind power plants

Large wind power plants (WPPs) can help to improve small signal stability by increasing the damping of electromechanical modes of oscillation. This can be done by adding a power system oscillation damping (POD) controller to the wind power plants, similar to power system stabilizer (PSS) controllers on conventional generation. Here two different design methods are evaluated for their suitability in producing a robust power system oscillation damping controller for wind power plants with full-load converter wind turbine generators (WTGs). Controllers are designed using classic PSS design and H∞ methods and the designed controllers evaluated on both performance and robustness. It is found that the choice of control signal has a large influence on the robustness of the controllers, and the best performance and robustness is found when the converter active power command is used as control signal. It is found that the classically designed controllers have fairly good robustness, but that H∞ controllers can provide better robustness.