Two-stage Optimization Method for Medium and Long-term Electric Quantity Security Check

In order to quantitatively evaluate the security risks of medium and long-term electric quantity transaction contract, a two-stage optimization method for electric quantity security check is proposed. In the first stage, the optimization model of electric quantity security check is established with the objective of minimizing the power flow over-limit for transmission equipment, and the optimal unit commitment result under the electric quantity constraints is obtained. In the second stage, the optimization model of electric quantity security correction is established by consider the security constraints of power grid strictly, and the power flow over-limit for transmission equipment is eliminated by adjusting the unit commitment result. The two-stage optimal method obtains the executable conclusion of electric quantity contract, and further to locate the reason why the electric quantity contract is not feasible, and how to adjust it. A case study based on actual data of provincial power grid indicates the effectiveness.