A Novel Method for Estimating Short Circuit Ratio in HVDC Applications

Inhalt:
The transition from fossil fuel-based power generation to renewable generation poses new challenges for existing power systems. To address these, the power grids of different countries are becoming more and more connected and receive major update to their grid infrastructure. High-voltage direct current (HVDC) systems are key to facilitate both these interconnections and the integration of an increasing share of renewables into the power grids. One concern of the new generation landscape is the continuously varying short circuit ratios due to the non-steady nature of renewable energy generation. Varying short circuit ratios potentially impacts how converter systems should respond to certain events in the power grid and therefore need to be assessed on a continuous basis. The assessment should in the best case not be non-invasive, accurate and fast. HVDC system’s proper control systems could fulfill this estimation task which is proposed in the paper. A purely passive method which is continuously executed based on small changes in the power grid is proposed, developed and validated. The algorithm performs accurately in PSCAD simulations and shows an error of below 6% with real field data from an existing HVDC converter station.