Abstract
In this paper it is presented a combined on-line hybrid transient stability formulation with a parallel processing state estimator. The transient stability assessment uses a time domain integration scheme to compute the initial system trajectory and the equal area criteria to obtain the transient stability margins and the critical clearing times. The state estimator that provides the pre-fault operating conditions uses a parallel processing approach. In this technique the power system is split into K areas, and each subsystem is supervised by a local control centre. The measurements in each area are collected in the individual local control centre that has at least one computer system for data acquisition, data processing and computation. The computer programs developed by the authors were applied to a multimachine power network. The results obtained with the proposed formulation were compared with the solutions produced by other methods. Finally, some conclusions that provide a valuable contribution to the understanding of the multimachine power system preventive control are pointed out.

Abstract
The fast development in electrical power networks and his consequent complexity, impose a more useful state estimation operational scheme, shortening the time interval between consecutive state estimations. Technical developments in distributed Energy Management Systems (EMS), based on fast data communication networks, open up the possibility of Parallel and Distributed State Estimation implementation. In this paper will be introduced and discussed some ideas for the implementation of Parallel ana Distributed State Estimation in electrical power systems. Will be boarding a solution methodology based on conventional state estimation algorithms applicable in local networks and will be analysed some results obtained with a IEEE test system so that we can appreciate the performances of the proposed method. An evaluation of the degree of natural decoupling in the state estimation problem is also performed, and will be compared with the results of computational experiments with standard WLS methods, in the integral and distributed version.

Abstract
In this paper we develop a theoretically robust and computationally efficient state estimator algorithm, to solve the WLS problem by using parallel processing. Technical developments in distributed Energy Management Systems (EMS), based on fast data communication networks, open up the possibility of Parallel Processing in the state estimation algorithms. We have analysed the computational aspects of the parallel processing. Moreover, we have simulated this state estimator parallel algorithm in the IEEE 30, 57 and 118 bus systems. The numerical accuracy of the simulation demonstrates the excellent computational performance of the parallel algorithm. Results of computational experiments are compared with standard WLS methods, in the integral and distributed version. An evaluation of the degree of natural decoupling in the state estimation problem is also performed. The results of computational experiments indicate that a distributed processing for state estimation, is the better way to adopt the parallel computing in power systems energy.

Abstract
This paper presents an efficient information debugging methodology, using a dynamic state estimation algorithm which, through the use of a dynamic model for the time evolution of the system state, will meets simultaneously two objectives: the filtering of the incoming data and the forecasting of the state vector one step ahead. Based on this last characteristic a scheme for the detection of suspicious information is built.

Abstract
This paper presents a new candidate method for on-line transient security assessment and enhancement based on pattern recognition techniques. Transient state variables are used as primary features and the classifier is obtained in two phases, through the combination of an optimum discriminant transformation together with a probabilistic procedure. The proposed security functions can be further refined by means of a second level classifier based on an optimal discrimination plane and using a weighted K nearest neighbor rule. It is shown that this method provides also an efficient and simple tool for on-line preventive control. Results obtained for several contingencies in the CIGRE test system are discussed.

Abstract
A new type of bus for load flow analysis is proposed in this paper; this type of bus, named PX, is particularly suited for modelling elements like static compensators or asynchronous generators. The inclusion of this PX bus in the Fast Decoupled Load Flow method is presented and discussed. Numerical results are reported when applying this approach to solve load flow problems in two standard systems.