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This study discusses the connection of wind farms (WFs) to power system through unified inter-phase power controller (UIPC) for enhanced transient stability of the power system. The power circuit of the UIPC is based on the conventional inter-phase power controller (IPC), which its phase-shifting transforms are substituted by two series converters and one shunt converter. During fault condition, the WF connected through UIPC acts as STATCOM with capability of the active and reactive power control at UIPC connecting point. Based on the UIPC model and low-voltage ride-through requirements of the new grid codes, a control system for active and reactive powers control is proposed for enhancement transient stability of power system. The proposed approach is validated in a four-machine two-area test system. Power systems computer aided design (PSCAD)/EMTDC simulation results demonstrate that the UIPC provides an effective solution for enhancement of transient stability of power system including WFs. [ABSTRACT FROM AUTHOR]

Generalized Unified Power Flow Controller (GUPFC) is one of the newest Flexible AC transmission system (FACTS) devices based on voltage source converters. This paper presents a developed model of GUPFC based on power injection approach. The series converters of GUPFC is represented by injected complex loads as function of the specified powers flow, while the shunt converter is represented as a synchronous condenser that provides the reactive power compensation to control the bus voltage magnitude. The main advantage of the developed model is that the original structure and symmetry of the admittance and Jacobian matrices can still be kept avoiding the changes of the original Jacobian matrix. Consequently, the complexities of the load flow are reduced. This model includes simple strategies for handling the operating constraints of GUPFC, including the injected series and shunt voltages magnitude, currents of the series and shunt converters, and the real powers exchanged in the converters. The strategies are based on decreasing one or more values of specified values or by modifying the specified values as a function of the required constraint limits. The developed model and proposed strategies for handling violation of GUPFC operating constraints are tested on IEEE test systems such as 57-bus and 118-bus systems. [ABSTRACT FROM AUTHOR]

In recent years, electronic power transformer (EPT), which is also called solid state transformer, has attracted great interest and has been used in place of the conventional power transformers. These transformers have many important functions as high unity power factor, low harmonic distortion, constant DC bus voltage, regulated output voltage and compensation capability. In this study, proposed EPT structure contains a three-phase pulse width modulation rectifier that converts 800 V AC to 2000 V DC bus at input stage, a dual active bridge converter that provides 400 V DC bus with 5:1 high frequency transformer at isolation stage and a three-phase two level inverter that is used to obtain AC output at output stage. In order to enhance dynamic performance of EPT structure, neuro fuzzy controllers which have durable and nonlinear nature are used in input and isolation stages instead of PI controllers. The main aim of EPT structure with the proposed controller is to improve the stability of power system and to provide faster response against disturbances. Moreover, a number of simulation results are carried out to verify EPT structure designed in MATLAB/Simulink environment and to analyze compensation ability for voltage harmonics, voltage flicker and voltage sag/swell conditions. [ABSTRACT FROM AUTHOR]

The compound active-clamp zero-voltage switching three-phase power factor correction (PFC) converter is used as the first stage converter of the heating power supply in the monocrystalline silicon growth furnace to achieve high efficiency and high power factor. Parameter uncertainty and variation are the main problems for the controller design of the converter. The conventional methods, including proportional–integral (PI) control, exact feedback linearization (EFL) control, etc., cannot deal with such problems. In this paper, we propose a model reference adaptive control for voltage outer loop to achieve adaptation for the load and capacitor variations, as well as a variable structure control with shrinking boundary layer for current inner loop to improve robustness to the parameters uncertainty. The simulation and experiment results show that the proposed controller improves the power factor and efficiency of the system, and it has better transient and steady-state performance with respect to the load variation, as compared with the traditional PI control method and the EFL control method. [ABSTRACT FROM PUBLISHER]

A double-ended forward converter with an input inductor-capacitor (LC) filter operating in discontinuous capacitor voltage mode is proposed in this study. The most important advantage of the proposed topology is that the operations of the proposed converter make the switches bear only a portion of the peak capacitor voltage without any extra control and auxiliary winding, which result in a relatively low switches voltage stress. This study presents a detailed analysis of the switch voltage stress. The experimental results for a 36 Vdc/100 W are presented. [ABSTRACT FROM AUTHOR]

This work presents three fuzzy variable structure control (FVSC) techniques applied to the current control loop in a three-phase synchronous rectifier. These techniques are based in a Takagi-Sugeno (T-S) fuzzy PI controller. The first controller is a first-order FVSC, used as a reference. Then, two FVSC strategies are presented and tested, a second and a third-order FVSC. These control schemes are first simulated and then tested in a general-purpose laboratory synchronous rectifier test bench. Experimental results show that control performance is good in all three schemes, achieving current harmonic compensation and power factor correction. [ABSTRACT FROM AUTHOR]

In this study, a power factor (PF) control for an AC-DC boost converter operating in light load condition has been presented. A passivity-based current control able to operate in either continuous conduction mode (CCM) and in discontinuous conduction mode has been implemented. A voltage proportional integral-based control with input feed-forward has been implemented in order to increase PF and regulate the DC output. A current observer, suitable for both operating modes has been adopted in order to eliminate the need for expensive current sensor. The proposed mixed conduction mode control scheme has been numerically tested using a powerful software simulation platform and compared with classical CCM control scheme. Experimental tests have been finally performed on a real boost converter controlled by a Texas Instruments microcontroller in order to validate the results and to prove the feasibility of the algorithm. [ABSTRACT FROM AUTHOR]

This paper presents a new control strategy for power factor correctors (PFCs) used to drive high-brightness light-emitting diodes (HB-LEDs). This control strategy is extremely simple and is based on the use of standard peak-current-mode integrated controllers (PCMICs), reducing its cost and complexity in comparison to traditional PFC controllers. In fact, this method is an alternative implementation of the one-cycle control to PFCs belonging to the flyback family of converters, without introducing high complexity for reducing the total harmonic distortion. In this case, the use of a simple exponential compensation ramp instead of a linear one is the proposed solution for drawing a sinusoidal input current. Moreover, the line current is cycle-by-cycle controlled, and therefore, the input-current feedback loop is extremely fast, which allows the use of this type of control with high-frequency lines. The proposed idea is to apply this simple control to a one-stage PFC in order to design a low-cost ac–dc HB-LED driver. However, the application of this control strategy to PFC belonging to the flyback family of converters is not obvious. Design-oriented considerations about its implementation in PCMIC will be provided. Finally, an experimental prototype of this driver was developed. [ABSTRACT FROM PUBLISHER]

The inconveniences of the reactive power are presented and from this are carried out the mathematical models of its economic effects applicable to secondary power systems. The effects taken into account are: the costs of the capacitors banks, the expenses of paying-off to the banks, the expenses of power losses to the banks, the benefits for the improvement of the power factor, included the reduction of power loss in the system, as well as the benefits for the liberation of the load capacity, to the case of companies where the latest aspect can represent an economic attractiveness. For the analysis after and before compensation, are consider load flow algorithm witch load model adjust. According to electrical tariff structures in Cuba, these effects are integrated in a function of economic analysis, for this case the net actual value, which serves as base for the position of the optimization problem, which can derive in the correct selection of the devices compensators. [ABSTRACT FROM AUTHOR]

This paper presents a dynamic study about the influences of distributed generators (induction and synchronous machines) and distribution static synchronous compensator (DSTATCOM) devices on the dynamic behavior of distribution networks. The performance of a DSTATCOM as a voltage controller or a power factor controller is analyzed. The impacts of these controllers on the stability and the protection of the system with distributed generators are studied. Simulation is to be carried out using DSTATCOM as voltage controller and power factor controller. [ABSTRACT FROM AUTHOR]

Abstract: A modeling method proposed for the optimization of the design of offline power factor correction controllers has been presented. Both simulated results and experimental confirmation of the results has been done. The transfer function of the current-control loop has been derived for specified operating conditions, and a Matlab script for plotting Bode plots of these transfer functions is developed. Preliminary results in modeling the boost converter by state space averaging appear credible, and could be effectively guided to the design of electric power system. [Copyright &y& Elsevier]