In closing transmission system loops after a blackout or a partial outage, the standing phase angle (SPA) across breakers should be below a preset value. Closing a breaker on a larger SPA can give rise to damage to system equipment, and can even provoke the recurrence of system outage. Power angle across a line is influenced by the transmitted real power, line reactance, as well as the voltage magnitude at both ends of the transmission line. SPA reduction has conventionally been made by rescheduling the production among generators or by load curtailment. In this paper, an approach is presented to achieve the desired SPA by using the generator terminal voltages as control variables. This allows the desired SPA to be attained in a shorter time. Due to the dependency of load power on voltage magnitude, load active and reactive powers are represented by a more detailed model of constant power, constant current, and constant impedance components. Constraints in operational variables which can restrict the control scheme are also taken into consideration. The effectiveness of the proposed approach in reducing the SPA is illustrated by case studies on a three-bus test system and on the IEEE 118-bus system. (C) 2017 Elsevier B.V. All rights reserved.

This paper investigates various approaches to relieve the transient stability constraint in restructured power systems. The approaches adopted fall into two broad categories: those based on eliminating the constraint in the least-cost way and those based on eliminating with the least possible rescheduling. The latter group can, on the other hand, emerge in the form of a pool-protected policy in which the bilateral contracts are rescheduled to maintain the stability or in the form of a contract-protected policy in which the realizable bilateral contracts are maximized while minimizing the rescheduling in pool market. Transient energy function (TEF) method is used as a tool to calculate the sensitivity of energy margin to the variations in the magnitude of generation and load. The effectiveness of the method is illustrated by case studies on Western System Coordinating Council (WSCC) 3-machine 9-bus power system and on the 10-machine 39-bus New England test system and the results are compared. The results are also verified by time domain simulations. (C) 2010 Elsevier B.V. All rights reserved.

This paper presents a high-accuracy technique for the assessment of harmonics and interharmonics in power systems. In the proposed method, a generalized eigenvalue problem is solved by making use of the matrix pencil method. It is a general method in the sense that it has the ability to predict the frequency, amplitude, and relative phase of frequency components present in a given signal, while the dc-off set and damping factors can be accurately estimated. It also offers a noise-resilient feature which helps to efficiently analyze the noise-contaminated signals. It shows a good performance in dealing with modulated signals as well. Due to its excellent accuracy, the proposed method is foreseen to properly work for the estimation of phasors which is a crucial need in the electrical networks. Different simulation and experimental cases are presented to evaluate the efficiency of the proposed method.