The European-wide goal of increasing the share of final electricity consumption from renewable sources to 27% by 2030 increases the supply volatility of the power system considerably. To manage this volatility, ancillary services for the power system become increasingly important. The most important short-term ancillary service is balancing power: it balances the electricity demand and supply instantaneously and, thus, ensures a constant frequency over time in alternating current grids. In most liberalized electricity markets worldwide, the procurement of balancing power is organized with the help of auctions. This thesis analyzes balancing power auctions theoretically and empirically and focuses on the current Austrian-German and the future European-wide Secondary Balancing Power (aFRR) auction design.