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Nowadays, there is a tendency to increase the capacity of wind turbines, multilevel converter is a realistic alternative in such high power applications. As the wind power penetration continues to increase, grid codes have been revised to require wind farms to operate as conventional power plants. This paper proposes a reconfiguration scheme of control strategies for doubly fed induction generator...
Active front-end converters with bidirectional power flow capability have been extensively used for utility applications of power electronics. Large passive filters are normally required at the grid side of the converter to mitigate switching EMI noise. This may become a critical issue, in terms of installation space and potential resonance of the passive filter. This paper proposes a hybrid active...
This paper presents performance characteristics of a novel soft switching three phase utility frequency AC (UFAC) to high frequency AC (HFAC) direct converter with PFC function for industrial induction heating and melting applications. The proposed ??simple three phase system?? consists of single phase UFAC to HFAC direct converter in each phase, three phase low pass filter and IH load. This power...
The Brushless Doubly-Fed Machine (BDFM) is a brushless electrical generator which allows variable speed operation with a power converter rated at only a fraction of the machine rating. This paper details an example implementation of the BDFM in a medium-scale wind turbine. Details of a simplified design procedure based on electrical and magnetic loadings are given along with the results of tests on...
It is well known that transition current mode control for power factor corrector can reduce the reversal recovery loss for the diode. This method can be realized using discrete control integrated circuit which requires zero-crossing detection circuit. In this paper, a novel control technique for digital-controlled power factor corrector to achieve transition current mode control is proposed. The switching...
The paper proposes a single-phase full-bridge positive/negative pulse charger with energy regeneration and adjustable power factor. Based on a generalized zero vector technique, a novel charging system which combines a single-phase boost rectifier with a buck converter is presented. The system forms a novel single-stage converter of AC to DC, and such a converter has both energy regeneration and power...
Two control schemes for active and reactive power of a double-fed induction generator with the stator connected direct to the constant frequency, three phase grid are described. First the direct and quadrature rotor current components are generated based on the mathematical model of the machine. The second scheme used a PI controller to generate the rotor current reference components. The principles...
From depletion of energy resources and consideration to natural environment, introduction of renewable energy facilities has been increasing annually. Moreover, introduction of photovoltaics has increased on the demand side. However, due to the fluctuating power from renewable energy sources, frequency and voltage fluctuations of power systems become problematic. At the same time, there has been a...
This paper presents a novel STATCOM configuration for voltage quality improvement in wind power generation systems. The proposed STATCOM is formed by cascading two 3-level inverters, `bulk inverter' and `conditioning inverter', through a coupling transformer. Both inverters are powered by dc-link capacitors and they are charged by a small amount of active power drawn from the grid. To minimize switching...
This paper investigates the control of a multi-level cascaded H-bridge STATCOM when used as a simultaneous active filter and VAR compensator. The control algorithms developed borrow heavily from control strategies used in variable speed drives, and use predictive current control and symmetrical PWM. A novel phase locked loop approach for the extraction of the harmonics and generation of the forward...
This paper presents voltage stability in power systems when connected by wind farm generators. Two models of wind generator, namely squirrel cage induction generator and doubly fed induction generator are used and based on steady-state model. P-V curve is used to express maximum loading factor in power system when wind farm was installed. The test IEEE 14 bus system is selected to show proposed performance...
A novel cost-effective and high-efficiency single-switch resonant inverter with power-factor-correction (PFC) scheme is proposed to drive a piezoelectric ceramic transducer (PCT) for an ultrasonic cleaner. The circuit topology is derived by integrating a flyback converter served as PFC stage with a class-E resonant inverter for driving a thin PCT at its resonance frequency. A unity power factor is...
We propose a universal field-oriented (UFO) control schemes for the rotor-side controller of doubly-fed induction generators (DFIG). The control block diagrams for different existing field oriented controllers (FOC), including stator flux oriented control (SFOC), rotor-flux oriented control (RFOC), and air-gap field-oriented control (AFOC), are unified in the same framework. Simulation comparisons...
In this paper, a new control strategy for a low cost series connected single phase PV module inverter is introduced that delivers full PV power (at MPPT) to the load together with voltage compensation. The inverter operates during the day time as an active power compensator as well as load voltage regulator under grid voltage sag, swell or even under normal condition. The compensating voltage provided...
A novel control method used in the half-bridge single-state power converter is presented in this paper. This proposed control scheme is to enlarge load regulation range in discontinuous conduction mode (DCM), while the new duty pattern will be derived to perform the variable-frequency control. Compared to the conventional control methods, the proposed duty cycle pattern within a switching period is...
In this paper, a novel discrete model has been proposed to simulate the controller IC UC3854. The main contributions are as followings: 1) The power stage of the Boost converter has been modeled by using the large signal approach and the loop gain of current program has been put forward; 2) The continues-time voltage control diagram has been investigated by employing equivalent power stage which contains...
Three phase photovoltaic grid-connected generation technology with maximum power point tracking (MPPT) and voltage control function is proposed in this paper. According to the equivalent circuit of the photovoltaic (PV) array, it builds the mathematic model of PV array. Based on the V-I characteristic curve, it calculates the MPPT of PV array in grid-connected system by using the Newton's method....
This paper presents an implementation of controlled rectifier with power factor correction (PFC) using single-phase matrix converter (SPMC). A current control loop (CCL) using standard proportional integral control was used to implement PFC to correct the pulsating nature of the input current to almost unity power factor form with low total harmonic distortion (THD) level well below the acceptable...
This paper presents a new method for power decoupling control of single phase AC/DC converters using three switch poles to achieve unity power factor operation at AC side and power decoupling function at DC side. The method proposed compensate the pulsating power at twice the grid frequency by absorbing low frequency ripple current to a DC decoupling capacitor through the third switch pole operation...
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