Advanced wide area monitoring system to secure transmission corridors during phases of high dynamic activity

The Indian Grid is characterised by widely dispersed generation and load points. Because of this there is large amount of power flow in the inter-regional grid in the east-west, east-north and the north-west corridors. Growth of Independent Power Producers and renewable generation are changing the nature of these power flows. Summer peak demand in the north also adds to the already stressed grid conditions. The power corridors are at present being monitored and analysed by SCADA and energy management tools relying on steady-state limits of the network equipment. While these tools are adequate under normal circumstances, it is inadequate in coming to terms with the true state of the grid in situations of high dynamic activity. This was proven during the blackout on two successive days in the end of July 2012 when almost 48 GW of load was impacted. This paper looks at how the current situation may be mitigated by implementing a Wide area critical care desk. Filtering the low frequency mode of oscillation from the acquired PMU data and subsequent mode analysis, operator is informed of the large and poorly damped group of generators. Analysing the corridor power flow influencing the mode and generators crossing the step, contributors of the oscillations present in the network would be identified. Once the source and the sink of the oscillations are known, operator will have the means for pro-active redispatch action to maintain stability. In addition, wide area phenomenon like load encroachment and situations leading to voltage collapse and network congestion can be brought under critical dashboard monitoring.