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This study concentrates on the strategic interaction among suppliers in a centralized market where electrical energy and spinning reserve are simultaneously traded. A bilevel optimization technique and a mathematical program with equilibrium constraints approach are utilized to develop optimal bidding strategy for competitive suppliers participating in these markets. The strategic behavior of each supplier is represented via a parameterized Supply Function Equilibria (SFE) model. Two versions of the parameterized SFE are considered. They are referred to as e-parameterization model (involving manipulation of the sole intercept) and (s, c)-parameterization model (involving arbitrarily manipulation of the slope and the intercept). A pay-as-bid pricing mechanism is assumed for settling the market and calculating the supplier profit from selling energy and spinning reserve services. A six-bus test system together with a number of case studies are used to illustrate the interaction between the energy and spinning reserve markets. Transmission limits and the supplier physical constraints are observed in this study. The extension of the method to include a multiperiod market with intertemporal constraints is discussed through numerical results. Index Terms--Bidding strategy, energy, Nash equilibrium, spinning reserve, Supply Function Equilibrium (SFE).

This paper presents a mixed-integer nonlinear optimization model for distributed generation (DG) placement in the distribution system. A multiperiod ac optimal power-flow model is developed for minimizing annual energy losses and determining the optimal site and size of DG units. Various system constraints and time-varying demands are incorporated in the model. A novel iterative method for solving the multiperiod DG placement problem based on the Benders decomposition technique is proposed, which reduces the computational burden and facilitates its practical application. Two case studies are presented to illustrate the efficacy of the proposed method. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Due to the recent advances in high power electronic industry and semiconductor technologies, many fast and advanced controllers and compensators have emerged. A variety of these devices, known as flexible AC transmission systems (FACTS) have many potential uses in power system control. Unified power flow controller (UPFC) is one of FACTS devices consisting of two PWM-converters and sharing a d.c. link. This paper proposes a new approach in which UPFC is used for power flow control in both steady state and transient conditions as well as harmonic compensation through an instantaneous control scheme, valid in general system conditions and applicable to all voltage–current waveforms. Also, the proposed control scheme incorporates a technique of reducing power oscillations during transient conditions. Simulation results show that the control scheme provides satisfactory performance, meeting the design objectives. [Copyright &y& Elsevier]