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The paper considers a control solution for integration of large offshore DFIG-based wind farms with a common collection bus controlled by a STATCOM into the main onshore grid using line-commutated HVDC connection. The main focus of the paper is a mathematically grounded study of the power system interactions that resulted in a plant model appropriate for a formal control design. A design procedure...
The paper presents a simulation for energy short term storage unit integrated into a stand alone hybrid wind diesel system. The energy short term storage unit is a flywheel device which is driven by a 6/4 switched reluctance machine (SRM) operating in motor and generator modes. The control strategy is developed to smooth the wind power turbulence fluctuations in order to decrease the fuel consumption...
This paper investigates advantages of new combination of the induction generator for wind power and the power electronic equipments. Induction generator is popularly used for the wind power generation. The disadvantage of it is impossible to generate power at the lower rotor speed than the synchronous speed. To compensate this disadvantage, expensive synchronous generator with the permanent magnets...
This paper deals with the study of the behavior of stand alone wind energy converters (WEC) based on permanent magnet synchronous generator (PMSG). First, the WEC chain is described and the model of each component of the conversion set is studied. At this stage, a special attention is given to incorporate the saturation effect in the PMSG model. Then, the obtained model is used to analyze the dynamic...
The first part of this paper intends to give an overview of the maximum power point tracking methods for photovoltaic (PV) inverters presently reported in the literature. The most well-known and popular methods, like the perturb and observe (P&O), the incremental conductance (INC) and the constant voltage (CV), are presented. These methods, especially the P&O, have been treated by many works,...
Wind power increases rapidly with increase of wind speed. In order to keep wind turbine running even at strong winds wind power capture has to be constrained. Efficient way for constraining wind power capture is the use of pitchable blades. For pitch controller design a suitable wind turbine model is needed. Finding mathematical model that would be a good representation of wind turbine system and...
This paper presents the performance of connecting two wind generation systems with the energy storage at the DC side. Energy storage is desirable to be installed to keep constant output from the wind power generation system. The DC connection of two wind power generation system helps to exchange power between the two systems and can suppress the disturbance of the output power to the utility systems...
In the paper an approach to real-time identification of pulse energy conversion system (PECS) parameters is developed. The approach is based on the preliminary bifurcation analysis and geometrical interpretation of the fractal properties revealed in PECS dynamics. The approach has in aim to establishing of a functional dependence between both phase variable values measured and parameter values sought
In this paper, investigation of effective snubber circuits in the three-phase AC to DC buck converter is presented. Based on the theoretical analysis and from the conventional matrix converters theory approach, the mathematical proof for an AC to DC power converter with unity input displacement factor (IDF) operation without current sensing, is provided. For the DC output current bulky inductance...
The effects on torque performance when using small voltage vectors of Matrix Converters is investigated in this paper. These vectors are used in order to reduce the electromagnetic torque ripple which appears when Direct Torque Control technique is used in Induction Motors. Direct Torque Control for Induction Motors using Matrix Converters is reviewed and it is pointed out the problem of the electromagnetic...
This paper presents a control method for permanent magnet (PM) motors based on a combination of a non linear full-order observer and a signal injection scheme. Mechanical-sensorless operating range down to zero speed is obtained using only voltage and current sensors. The signal injection scheme uses the asymmetry of the motor's d and q axis inductances to estimate rotor position and speed. Such asymmetry...
A procedure for improving the design of a servo motor by means of finite-element method (FEM), optimization using differential evolution (DE) and cost analysis is presented. A comparative analysis has been carried out for four different motor designs taking into account the motor performance and the cost of the investment for manufacturing of the redesigned motor. The reliability of the FE model has...
In this paper, the test voltage injection coupled with tracking of magnetic saliencies created by saturation and rotor slotting was used for shaft sensorless speed control of induction motor drives at zero and low speed. Method does not require additional wire connections and is usable for star or delta machine connection. The paper is proposing low memory method of elimination saturation effect from...
In this paper, a digital resistive current (DRC) control for parallel interleaved DC-DC converters is proposed. Converting the effective input characteristic of the converters seen by the source as a resistive load sink for current sharing, the proposed control scheme achieves current mode control, like the conventional analog charge current mode control. Also, the sub-harmonic oscillation at the...
Iron losses due to flux harmonics in stator cores of Pulse-Width-Modulation [PWM] back -to-back inverter-fed induction motors have a major effect on system efficiency. A new generation of direct ac-ac matrix converters offer important advantages over classical frequency converters such as absence of bulky and temperature sensitive dc-links and possible adjustment of power factor. The paper presents...
Nowadays the most used multilevel topology for variable-speed wind turbines (WTs) is the a back-to back three-level NPC (Neutral Point Clamped) VSCs (voltage source converter). One of the most critical elements in the design of this type of converters is the DC-bus capacitors. The calculus of these depends on the same factors that the same two-levels topology, and, moreover it is function of a low...
An adaptive model applied to PWM DC-DC converters is presented in this paper. Parasitic resistors have been considered in the converter. The coefficients of the state-space matrices, which depend on the parameters of the circuit, are calculated on-line. In the proposed method, the state vector variables should be sampled in real time, and the coefficients of state-space matrices are estimated by means...
This paper presents a method of using Selective Harmonic Elimination PWM (SHEPWM) as part of a control strategy for a multilevel rectifier. Such a power converter can be applied as part of a solid-state replacement for a distribution transformer. The paper discusses problems with DC link voltage balancing on the converter and how SHEPWM can be manipulated to solve these problems. The full DC link...
The Ishikawa and Murai zero current switching inverter offers promising characteristic for several applications. Nevertheless, to date the control issue was not yet fully addressed. The paper reviews the converter evidencing the nonlinearity, the load-filter resonance issue, and the resonant time duration. An equation for the forecasting of the resonant times is checked. Consequently, a modulator...
This paper is concerned with the development of a new type of power supply for high power RF applications for CW operation. Losses are reduced by the use of zero current switching. This allows for a high operating frequency and minimised transformer and filter size. Preliminary practical results have been found to be promising, with design of the resonant circuit and isolating transformer being fundamental...
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