Jose L. Martinez-Ramos

Security management under uncertainty: From day-ahead planning to intraday operation

In this paper, we propose to analyse the practical task of dealing with uncertainty for security management by Transmission System Operators in the context of day-ahead planning and intraday operation. We propose a general but very abstract formalization of this task in the form of a three-stage decision making problem under uncertainties in the min-max framework, where the three stages of decision making correspond respectively to operation planning, preventive control in operation, and post-contingency emergency control. We then consider algorithmic solutions for addressing this problem in the practical context of large scale power systems by proposing a bi-level linear programming formulation adapted to the case where security is constrained by power flow limits. This formulation is illustrated on two case studies corresponding respectively to a synthetic 7-bus system and the IEEE 30-bus system.

Exploiting the Use of DC SCOPF Approximation to Improve Iterative AC SCOPF Algorithms

This paper focuses on improving the solution techniques for the AC SCOPF problem of active power dispatch by using the DC SCOPF approximation within the SCOPF algorithm. Our approach brings two benefits compared with benchmark SCOPF algorithms: it speeds up the solution of an iterative AC SCOPF algorithm thanks to a more efficient identification of binding contingencies and allows improving the objective by an appropriate choice of a limited number of corrective actions for each contingency. The proposed approach is illustrated on five test systems of 60, 118, 300, 1203, and 2746 buses.

Enhancing the integration of renewable sources in distribution systems using DC-links

This work proposes the use of DC-links between existing radial distribution feeders so that full advantage is taken of their maximum capacity, which is particularly important when new distributed generators are to be connected at the distribution level. An optimization tool is developed to determine the optimum settings for the DC-link control variables, in order to maximize the penetration of dispersed sources subject to customary electrical constraints. Simulation results regarding two real networks are presented to illustrate the former advantages. Also, improvements in system operation resulting from the presence of DC-links are studied and discussed. A real loss model for the DC link is considered in all test cases.

DCOPF contingency analysis including phase shifting transformers

This work deals with a new formulation for the Direct Current Optimal Power Flow (DCOPF) including the corrective actions related to the phase shifting transformers. The formulation is based on the outage of generators and/or branches modelled as fictitious injections of active power. The inclusion of the sensitivities of the phase shifting transformer with respect to the injected powers is one of the novelties of this paper. By including the fictitious injections in the optimization problem, the injections are adjusted to the post-contingency state as a consequence of the corrective actions carried out by the DCOPF to bring the system back to its normal state. Consequently, when the analysis of contingencies is performed, the classical topological analysis and the subsequent analyses are avoided with this approach. The DCOPF includes as corrective control variables the rescheduling of active power generations, phase shifting transformers and, if required, permitted load shedding. The IEEE-RTS of 24 buses is used as benchmark network to assess the properties of the proposed approach.