Contingency Constrained Optimal Power Flow (CCOPF) differs from traditional Optimal Power Flow (OPF) because its generation dispatch is planned to work with state variables between constraint limits, considering a specific contingency. When it is not desired to have changes in the power dispatch after the contingency occurs, the CCOPF is studied with a preventive perspective, whereas when the contingency occurs and the power dispatch needs to change to operate the system between limits in the post-contingency state, the problem is studied with a corrective perspective. As current power system software tools mainly focus on the traditional OPF problem, having the means to solve CCOPF will benefit power systems planning and operation. This paper presents a Quadratically Constrained Quadratic Programming (QCQP) formulation built within the matpower environment as a solution strategy to the preventive CCOPF. Moreover, an extended OPF model that forces the network to meet all constraints under contingency is proposed as a strategy to find the power dispatch solution for the corrective CCOPF. Validation is made on the IEEE 14-bus test system including photovoltaic generation in one simulation case. It was found that in the QCQP formulation, the power dispatch calculated barely differs in both pre- and post-contingency scenarios while in the OPF extended power network, node voltage values in both pre- and post-contingency scenarios are equal in spite of having different power dispatch for each scenario. This suggests that both the QCQP and the extended OPF formulations proposed, could be implemented in power system software tools in order to solve CCOPF problems from a preventive or corrective perspective.

We report a comparative frozen polarization study in three piezoelectric polymers: one polyimide without –CN dipolar groups (poly0CN), and two more that differ in the position of the –CN dipolar group present in the repetition unit (poly2-4 and poly2-6). The values of the dielectric permittivity and frozen polarization show that the participation of N-phenylphthalyimide group depends strongly on the curing process. For totally cured samples this group has little influence on the value of remnant polarization. The study was performed by dielectric measurements and by Thermally Stimulated Depolarization Current (TSDC) technique.

The problems originated by fire are important enough to carry out studies related to ignition, flame spread, combustibility, and smoke suppression for the purpose of obtaining materials with better fire behaviour. An improvement in fire properties can be achieved using fire retardants and smoke suppressants. Fire retardants can act by means of chemical reactions where the combustion presents radicals with high energy in the gas phase. They can also react physically by several methods: developing a layer which protects the material from ignition on the surface of the substrate, giving off non flammable gases such as H₂O, CO₂, SO₂, HCl, etc., in order to dissolve the flammable gases and withdrawing the oxygen from the fire area in the gas phase, improving certain reactions such as endothermic ones or surface dehydrations. On the other hand, smoke suppressants can also act physically and chemically (by means of Red-Ox reactions) in the condensed and gas phases. The present work focuses on the study of SMC-LP(Sheet Moulding Compound Low Profile) materials which are widely used in sectors such as: automotive, transport and building. In SMC low profile process, the polyester resins are mixed with thermoplastic additives. In this way, the formulation obtained is called low profile due to the contraction inside the mould tends to zero. On the other hand, using the proper process it is possible to obtain fibre reinforced plastics formulations with different fire retardant and smoke suppressants. The main objective of the present work has been an exhaustive analysis of the possible effects and interactions in fire and mechanical properties due to the different fillers added. This study has been carried out by means of an experimental design with statistical analysis of the results. The scope is focused on a further optimisation of these sorts of materials, in order to obtain a wide range of suitable formulations.