Sub-synchronous oscillations between FPC wind farms, VSC-HVDC links and nuclear power plants

Sub-synchronous oscillations between large synchronous generators and voltage source converters, VSCs is an emerging topic with the increased penetration of grid connected VSCs. There are several different study methods used for evaluating the risk for sub-synchronous oscillations.

In this report, the study methods for sub-synchronous oscillations including large synchronous generators and VSCs are evaluated regarding the suitability for different systems. Also, converter design and control are described with focus on the contribution to sub-synchronous oscillations.

It is shown that there are screening methods suitable for finding risks for possible sub-synchronous oscillations. For evaluating the risk of oscillations between a certain synchronous generator and a VSC, there are frequency scanning methods that can be used together with time domain simulations.


Five solution tracks leading to Nordic carbon neutrality

If the Nordic countries are to reach their climate targets the rate of emission reductions must increase fivefold compared with the previous decade. Stronger grids, increased flexibility, large scale deployment of wind and solar energy, electrification of transport and CCS are all decisive factors to reach Nordic targets.

18 okt 2021

Pressure-time method test rig operational at LTU

The pressure - time method is a discharge measurement method commonly used to estimate the flow rate in hydro-power plants to assess the turbine hydraulic efficiency. The method needs further development for application to low head hydraulic turbines where the intake cross-section is not constant.

4 okt 2021

Tax Reduction for New Technology

This year, the much-requested investment support for solar will be replaced Tax Reduction for green technology. The new deduction gives private individuals a tax reduction for material and labor costs. Amelia Oller Westerberg has investigated how the costs are distributed when installing solar cells on a residential roof.

16 mar 2021

Further steps taken to improve power quality and smart grid diagnostics

What are the root causes and the direction of power quality disturbances? Using machine learning-based methods the Gothenburg startup, Eneryield, has developed new ways of analysing these disturbances. Here you can read about ways in which this method can be made accessible for grid-operators.

3 nov 2020

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Lena Max, Andreas Petersson, Pehr Hjalmarsson