Abstract
With the development of synchronized phasor measurement technology in recent years, it gains great interest the use of PMU measurements to improve state estimation performances. In this paper, a mixed measurement (SCADA and PMU measurements) state estimator is proposed. Several measures useful for evaluating various aspects of the performance of the mixed measurement state estimator are proposed and explained. State Estimator validity, performance and characteristics of the results on IEEE 14 bus test system are presented. © 2012 IEEE.

Abstract
In the last years the importance of the security analysis has been increasing, due to economical and environment constrains. The operation of an electrical power system is a complex task due to the high degree of uncertainty and the large number of parameters involved. This paper is devoted to the presentation of an efficient steady-state contingency classification using the Rough Set Theory. The developed technique produces a classification of the system operating in four possible states. The powerful methodology developed was applied to a test power network in four different scenarios. The numerical results were compared and analysed in order to obtained important conclusions that provide a valuable contribution to the understanding of the power system security problem.

Abstract

Abstract
Nowadays, the large penetration of wind power generation poses new challenges for the dynamic voltage stability analysis of an electric power system. In this paper is studied the influence of the reactive power management for wind power plants in the dynamic voltage stability of an electric power network under a fault condition, considering two different Doubly-Fed Induction Generators (DFIG) models. The simulation results were obtained using the EUROSTAG software package.

Abstract
In this paper it is proposed a technique to identify the relevant neighbouring electric power systems using the Horizontal Network scheme. The developed methodology was applied to study the IEEE 118 test power network and the Iberian systems. All simulations were performed using the computational software package PSS®E developed by the Siemens/PTI. From the simulation results, some conclusions that provide a valuable contribution to the understanding of the impact of the cross-border interconnections between the countries will be pointed out.

Abstract
This paper presents a new method for the detection of the point of collapse and a new index for the definition of the distance of the voltage collapse point. Performance index to detect and predict stability problems such as the voltage collapse have been a permanent concern for researchers and technical staff in power systems operation. This index can be used on-line or off-line to help operators determine how close the system is to a possible collapse and is a useful analysis tool for planning in power systems too. Numerical experiments using standard IEEE 14 and 57 bus systems show that the proposed method can compute the voltage collapse point using several different scenery of load increase or line outages. The methodology proposed may be easily implemented in any power flow program.