Experience with dynamic system monitors to enhance system stability analysis

Dynamic system monitors (DSMs) are now used in the Pacific Gas and Electric (PG&E) system to detect emerging transient and steady-state problems before they cascade into a major disturbance, to help analyze major operational problems, to verify system transient and steady-state system response, and to improve stability studies. The DSM hardware, software, site selection, and early results are discussed. DSMs provide 10 min of recording time, and thus cover the critical period addressed by stability studies. The monitors have advanced triggering logic, extended recording times, and direct access by engineers responsible for stability studies and evaluating online system performance. Three recent recordings that demonstrate the value of dynamic system monitoring in the PG&E system are described. Capturing online disturbance data with DSMs and performing validation studies remain the key to improving the accuracy of stability studies