Risk limiting dispatch with ramping constraints

The increasing penetration of renewable resources poses a challenge to the reliable operation of power systems. In particular, operators face the risk of not scheduling enough traditional generators when renewable generation becomes lower than expected. This paper studies the optimal trade-off between the system risk and the cost of scheduling reserve generators. The problem is modeled as a multi-period stochastic control problem, and in particular the ramping constraints on the generators are explicitly considered. The structure of the optimal dispatch control is identified. Based on the derived structure results, two types of control policies are proposed to efficiently compute the optimal dispatch: (i) a chance constrained policy, and (ii) efficient look-ahead policies. Utilizing real system data, the chance constrained dispatch is shown to outperform the look-ahead policies and to be robust to changes in the probability distribution of the uncertainties involved in the problem.