Evaluation of Power Oscillation Damping in the Nordic Grid Using HVDC

Abstract: With a rapid transition towards renewable energy sources and increasing demand for electricity, we are facing major changes in the electricity grid. With increased congestion and reduction of inertia the grid is becoming more sensitive to rotor angle stability issues, such as the stability of interarea modes or power oscillation damping (POD). This thesis shows that the use of local measurements for POD improvement could lead to reduced transient rotor angle stability. Depending on fault location it is shown that reduction of the first swing is not always feasible, and depending on the controller the first swing could be amplified and in the worst case lead to a power blackout due to the tripping of generators and transmission lines. The reason for the behavior is, among other things, rooted in the fundamental limitations of using local measurements, where the estimate of the inter-area mode detects the wrong signs of the disturbance. Nonlinear simulations are performed in the nordic32 bus Simulink model in order to validate the results.