Forced Oscillation In Indian Grid - Case Study

Forced oscillations pose real threat to the reliability and security of the grid. Though in all the above cases magnitude of oscillation in the inter-regional tie line was less than the magnitude of oscillation at the source itself, which meant oscillation was attenuated by the system frequency response but if any oscillation emanating from generator controller is in resonance with existing modes of grid, it can be catastrophic. If left undamped, it can be detrimental for alternator hardware. Synchrophasor has been the savior, thanks to the granular data and keener analytics available from WAMS. By comparing the signatures of PMUs installed at different locations the node associated with maximum amplitude & highest negative damping can be found out. However, there is a need for suitable tool to assist the system operator in accurately identify the erring controller in real time, so that time taken to trace it by analyzing SCADA data, can be saved. Once the erroneous controller of the generator is identified either it has to be disabled or the generator itself is to be desynchronized for ensuring systems reliability and also for securing the life of the generator.