System observability indices for optimal placement of PMU measurements

In this paper a new parameter - Observability Level Assessment (OLA) - is introduced and defined. The parameter can be used to determine the observability of an electrical network. The defined five levels of the OLA index provide statements if the Phasor Measurement Units (PMU) have been placed in a sufficient number and if optimal measuring sites in the grid have been chosen. Therefore, the OLA index can be used to investigate whether the advantages and potential applications of time-synchronized measurements in the state estimate can be taken into account. In addition, two procedures for the placement of the PMU will be presented, which allows for the optimal distribution of measuring points in the system and thus the achievement of the preferred OLA level. Based on a benchmark power system evaluation of placement approaches, OLA levels will be examined.