Stochastic unit commitment for power systems with offshore wind farms towards frequency resiliency

To enhance the resilience of transmission systems with offshore wind farms before the advent of typhoons, a proactive unit commitment scheme is proposed. A novel scenario tree is proposed to quantify the uncertain impacts of typhoons on offshore wind farms, transmission lines, and system states, where the inertia support from offshore wind farms and random system state are in-cooperated. The frequency security constraint is captured by a multi-variative piece-wise linear function, where the frequency nadir are simulated under varying inertia and disturbance combinations. The unit commitment problem is formulated as a two-stage stochastic optimisation problem with nonlinear recourse. This problem is solved by a multi-cuts Benders decomposition algorithm with finite iteration convergence property. Simulations are conducted on a modified IEEE-RTS 79 test system with offshore wind farms. Results verify the effectiveness of the proposed model regarding the load shedding and frequency nadir enhancement.