Tie-line modelling in interconnected synchrophasor network for monitoring grid observability, cyber intrusion and reliability



The incorporation of a tie-line between two areas may be beneficial in two aspects. One is the reserve capacity of the assisting area support to the assisted area, and the second is that the number of Phasor Measurement Unit (PMU) requirements will become smaller for complete observability of the interconnected grid. The objective function is formulated to integrate the analysis of observability and reliability for the two interconnected synchrophasor networks. The effect of the Zero Injection Bus (ZIB) is included in the observability constraints to reduce the number of PMUs deployed in the system. The number of optimal PMU deployments will be greater for two interconnected systems in comparison with a single area. Therefore, interconnected systems become more vulnerable to cyber risk. The paper discusses the cumulative analysis of system observability and reliability during an anomaly situation that occurs with a PMU device due to a cyber-attack. The reliability indices Interconnected System Load Interruption Probability (ISLIP) and Interconnected System Demand Not Supplied (ISDNS) are evaluated when an anomaly occurs with optimally deployed PMU in the network by including and excluding the effect of ZIB. By doing so, the most reliable location for PMU deployment can be obtained for both the area. Reliability Test System (RTS)-24 bus is used for each area to modify the test system by incorporating tie-lines between them.