Calculation of Cyber Security Index in the Problem of Power System State Estimation Based on SCADA and WAMS Measurements

State estimation is an important procedure providing reliable quality information for control of electric power system (EPS). The paper focuses on the possible consequences of cyber attacks on the state estimation results. To measure the impact of cyber attacks on the state estimation results we introduce an index of cyber security which is determined on the basis of a set of characteristics that define the accuracy of the state estimation results. Since these characteristics are not deterministic the cyber security index is estimated by the method of fuzzy sets. The index of cyber security makes it possible to reveal the most vulnerable facilities in electric power system and develop a strategy for the improvement of their cyber security. The suggested strategy implies the use of PMU measurements coming from WAMS in addition to SCADA measurements.