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Stability issues are a major concern in railway grids. Although these problems are most experienced in 16.7-Hz applications, low-frequency oscillations also occur in 50-Hz railway grids. In this paper, an advanced multivariable control concept is presented. Beside achieving very good dynamic behavior, the approach improves the introduced stability problem. The proper operation of the control is verified...
Stability aspects are a major concern in railway-traction applications. It is well-known that low-frequency oscillations occur in 16.7-Hz railway-grids. They can be initiated either by impedance variation or by multiple traction vehicles active in one feeding section. This paper focuses on the emulation of many traction vehicles starting up in the same feeding section and hereby causing instability...
In this paper a study of the fuzzy logic controller for ZCS Boost converter is presented. The fuzzy logic controller provides an adaptive control for better system performance and it is used for controlling the non-linear processes. FLC is designed to regulate the output voltage of the converter. The converter is modeled and analyzed using Matlab/Simulink software and it was designed in an closed-loop...
It is proposed in this paper a methodology to obtain optimal controllers gains for the rotor-side converter of doubly fed induction generators (DFIGs) using a genetic algorithm approach. The main objective is to enhance the operational security and robustness of the power system, by a more effective contribution of the DFIG controllers to the system controllability. To reach this goal, the crow-bar...
This paper explores the performance of alternative voltage control strategy applied to direct drive synchronous wind generators, more specifically with permanent magnetic (PMSG). The reactive power control of the grid-side converter is investigated for voltage control purposes. In Brazil, the Grid National Operator (ONS) requires that wind turbines stay connected to the grid during voltage dips, but...
This paper deals with the Model Predictive Control of Uninterruptable Power System(UPS) using two level converter. The controller uses the d-q plane model of the system to predict the behavior of the state including output voltage at each sampling time. An equilibrium state and corresponding equilibrium inputs for the given reference output voltage is determined from the system model. Using the derived...
This paper deals with an application of the power balance theory in a voltage and frequency controller (VFC) of an autonomous wind power generation using an isolated asynchronous generator (IAG) feeding three-phase four wire loads. The reference generator currents are estimated using the power balance theory to control the voltage and frequency of IAG system. Three-leg voltage source converter (VSC)...
A three-phase four-wire DSTATCOM (distribution static compensator) based on three-leg VSC (voltage source converter) isolated with a star/hexagon transformer is demonstrated for power quality enhancement in a three-phase four-wire distribution system. The DSTATCOM is controlled to compensate the reactive power, eliminate harmonic currents, balances the load and also to mitigate the neutral current...
A current sensing circuit which is fully integrated suitable for low voltage buck regulator is presented. The current sensing circuit presented operates with accuracy close to 100 percent. It is targeted to be fabricated with 180 nm UMC technology. This IC senses faithfully till frequencies 2 MHz and hence it works well for the buck converters whose switching frequencies are up to 2 MHz. It is designed...
This paper presented a system of Aircraft Power Distribution System (APDS). Large-signal models of synchronous generator, three phase boost converter and inverter was developed. A two-port network interconnection rule was chose as a special convention about voltage and current variable of component exchange, and a system level model of APDS was performed. The system model was designed to assessment...
This paper presents a marine generator control system which BDFM control winding side is controlled by commercial converter. Two problems of the commercial converter in control system is solved. One is the common commercial converterpsilas output voltage and frequency at constant V/F curve, the other is it canpsilat feedback energy to AC power. Based on generator voltage and frequency loop , we discuss...
In this paper, two control strategies for three-phase series-parallel uninterruptible power supplies are compared. A series-parallel UPS consists of a parallel and a series converter. In this topology, most power required by load is supplied directly from AC line during standby mode. Therefore the overall efficiency is higher than that of a conventional UPS. Traditionally, the control strategy of...
The control for a diode-clamped three-level half bridge converter is researched in this paper. The reasons for the input current distortion around the zero-crossing point of the input voltage based on the voltage zero-crossing detection control are analyzed in detail, and a hybrid control which combines the reference voltage feed-forward control with the feedback control is proposed to prevent the...
A high performance modular three-phase utility-interactive converter is designed and implemented in this paper. This converter has three operation modes: grid-connection inverter mode, stand-alone inverter mode and rectifier mode. Control principles and modes of every mode are analyzed in detail and the modular design method is adopted. A simple but valid control strategy is proposed. Finally a 10...
In this paper, a novel active boost converter for the SR drive is proposed. An active capacitor circuit is added in the front-end. Based on this active capacitor network, when the boost switch turns off, this network seems as a passive capacitor network. And the voltage of boost capacitor can keep balance with the DC-link voltage automatically. In the capacitor network, the discharging voltage is...
To develop and apply renewable energy, one of the key technologies is that a kind of inverter outputting high quality sinusoid signals to power network is required. This paper proposed a three-phase buck-boost inverter, which can generate a three-phase ac output voltage larger than the dc input one. Its basic configuration is introduced, and the system stability of open-loop is analyzed by constructing...
In this paper, a novel passive boost converter for SR drive with high demagnetization voltage is proposed. A simple passive circuit is added in the front-end of conventional asymmetric converter, which consists of three diodes and one capacitor. Based on this passive network, the two capacitors can be connected in series or parallel in different operation status. So the terminal voltage of the converter...
This paper presents the analysis and operation of doubly fed induction generator (DFIG)-based wind power generation system under unbalanced network voltage conditions. The limited voltage and current ratings, the control capabilities of both the grid-side and the rotor-side converter (GSC & RSC) for unbalanced network voltage compensation are investigated in detail. A new current control scheme,...
A dynamic model of back-to-back voltage source converter under synchronous rotating d-q coordinate system is developed. The system is transformed to a new equivalent nonlinear system which consists of a linear decoupled subsystem and a nonlinear subsystem characterizing the dynamics of the DC-link voltage in terms of the state variables in the linear subsystem via the feedback linearization technique...
With the development of renewable energy generation and the requirement for grid-connected distributed generation system, wind power system with full-size convertor becomes the fashion. A simple, close-loop but efficient snubberless method (AVRF) to suppress turn-off overvoltage in a 750 kW convertor using Infineon IGBT3 is showed, which makes the convertor compact and robust.
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