Pseudo-random Simulation of Synchronous Interconnections of Polish and German 110 kV Grids

Abstract

The is a study of the power supply of a separated portion of a 110 kV grid on the Polish side from the German 110 kV grid. The Polish and German power systems are interconnected by exchange lines on the level of 400 kV and 220 kV only, so the separation of a 110 kV island without power supply interruption shall require an additional short-term interconnection for synchronous operation of the two systems with a 110 kV line. The voltage angle offset in the connected 110 kV nodes depends on the equivalent reactance of the adjacent systems’ interconnection at the transmission grid level, and on the power flow in the exchange lines. At the planning stage, in simplified analyses of such cooperation, the equivalent reactance and exchange power can be considered as random variables with uniform probability distribution. Random values of the reactance and exchange power at predetermined intervals can be generated by using a pseudo-random number generator, and the angle offsets for random reactances and random exchange powers can be calculated from the functional dependency. The random angle offset values determined in this way undergo statistical analysis, which allows estimating the probability of exceeding the angle offset limit. These considerations are illustrated by an example calculation.