Voltage Control in Power Systems:Preliminary Results Automatic Control Laboratory Swiss Federal Institute of Technology (ETH) T. Geyer, G. Ferrari-Trecate, M. Morari in collaboration with Mats Larsson ABB
Optimal Control Problem Subject to • Dynamics (in MLD form): • Soft constraints on bus voltages :
Receding Horizon Control • Optimize at time t (with new measurements) • Only apply the first optimal move u(t) • Repeat the whole optimization at time t +1 • Advantage of on-line optimization: Feedback!
Tuning of Cost Function • Violation of soft constraints is penalized by: • Choose weight R on u such that: No constraint violation: nominal control: > ultc voltage reference > capacitor bank Constraint violation: emergency control: > all controls including load-shedding
Conclusions • Control problem: • MPC is able to stabilize the load voltage V4m with N=2 and Ts=15sec without using load-shedding • solution time 8sec..2min (PC with 1GHz) • but: there remains a control error • Outlook: • observer • model reduction • reachability analysis • large-scale problem