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An open-loop and closed-loop operating boost-power-stage converter with relatively low damping factor exhibit resonant behavior in transient conditions. Such an undamped transient characteristic introduces overshoot to the control-to-output-variable transfer function, which is also visible in the inductor current transient behavior. Therefore, due to the either too large duty ratio or voltage-reference...
This paper proposes a transient modeling and analysis method for the fractional-order DC-DC converters in continuous conduction mode (CCM), in which a fractional-order Buck converter is taken as an example. By extending the usage of equivalent small parameter method (ESP), the converter is modeled by a general state vector differential equation. Then by adopting the principle of harmonic balance,...
In this paper, a fully ZVT auxiliary cell for boost type resonant converters is proposed to achieve soft switching in ON-OFF control mode. In conventional ON-OFF methods, transient and switching losses at the beginning and end of each power pulse decrease the overall efficiency of the system at high modulation frequencies. This ZVT cell offers zero voltage switching without imposing extra resonant...
This paper proposes an adaptive DC-bus stabilizer for single-phase grid-connected voltage source converter (VSC) with small-scale renewable energy integration. To enhance converter's power density, the conventional active power decoupling (APD) techniques were adopted to reduce the DC capacitance by compensating the inherent second-order harmonic power ripples in the single-phase VSC. However, it...
A modular multilevel converter (MMC) with traditional cascaded PI control structure suffers from poor steady state and dynamic performance. This is due to the limited harmonic rejection capability of PI controller thus failing to alleviate even order harmonics in circulating current and due to the slower outer average voltage control loop resulting in significant deviation in submodule capacitor voltages...
Nowadays, a clear trend of increase of system voltage to 800 kV AC and above can be observed in the world. This calls for the need of having test facilities to verify the fault current interruption performance of circuit breakers for such “super grids”. Standard synthetic test-methods for fault current interruption verification cannot be applied to circuit breakers of 800 kV and above, and alternative...
The paper has presented a new augmented buck converter to improve its transient performance. At first, an augmentation circuit based on diode-capacitor topology is introduced. The voltage across the inductor can be increased during load transients, and the rate of inductor current can be higher compared with conventional buck converters. Then, a hysteresis control algorithm based on output voltage...
Capacitor-switching operation can be used to measure network harmonic impedance. Via the transient components of voltage and current after capacitor switching, the harmonic impedance of PCC (Point of Common Coupling) can be calculated. To improve measurement accuracy, the TLS-ESPRIT algorithm is introduced in this paper to filter out noise and fundamental components in voltage and current signals...
This paper proposes the equivalent circuit of dynamic VD (PVD) in multi-break vacuum circuit breakers (VCBs). The equivalent circuit is composed of controlled post-arc sources, post arc resistors and equivalent capacitors. The PVD is divided into four processes: the initial transient recovery voltage (TRV) process, the oscillating TRV process, the stable TRV process and the power-frequency voltage...
High-voltage direct current (HVDC) circuit breaker with rapid fault clearing is an important equipment for protecting DC transmission system. The mechanical vacuum circuit breaker based on artificial current zero (ACZ) is excellent to interrupt the large current. A prototype of mechanical HVDC circuit breaker based on ACZ is simulated by Matlab in this paper. The main circuit breaker and the commutation...
The transient interruption characteristics and reignition conditions of direct-current (DC) forced current zero for vacuum interrupters in 270 V power-supply systems are discussed. Three stages are identified in forced interruption: DC arcing stage, current commutation stage, and voltage recovery stage. During the current commutation stage, the reverse peak current coefficient k, which is a key design...
This paper presents three implementation algorithms of compound elements pseudo-transient analysis to find DC solutions for nonlinear LSI circuits. In former researches, CEPTA was implemented in SPICE-like simulator with the merits that the size of Jacobian matrix is not expanded during the calculation. While the inserted pseudo parts are converted to some certain equivalent circuits, the conventional...
The transient performance of a DC power supply strongly depends on the loop design and output filter sizing. Most of the time, the finite loop bandwidth imposes the need of a large output filter capacitor in order to comply with the required regulation performance and stability margins. In space applications the linear conductance control principle has been used for a long time. It reduces the voltage...
The paper deals with a single-phase induction machine operating as a stand-alone self-excited single-phase induction generator for generation of electrical energy from renewably energy sources. By changing number of turns and size of wires in the auxiliary stator winding, considerable improvement of performance characteristics of the generator were obtained as regards no-load and load voltage of the...
In the paper, sudden short-circuit transients at terminals of an autonomous single-phase induction generator were simulated using field-circuit 2D model of the single-phase induction generator. The transients at terminals were calculated for different configurations of capacitors in stator windings. Some experimental results showing re-excitation of the stator voltage after sudden short-circuit at...
This paper presents a method to model external capacitors behavior face to continuous and transient events. Temperature and the physical dimensions of the capacitors have been considered in order to predict Electromagnetic Compatibility performances of an equipment or a system. The different tests were performed on ceramic capacitor series X7R from Murata. A model has been developed in Verilog-A....
Recently, distributed generations (DGs) have been widely used in distribution networks. Using DGs in the grid-connected mode leads to increase of the fault current level. This increase can affect the existing equipment especially circuit breakers (CBs) and operation of overcurrent relays. Current limiting reactor (CLR) has been proposed to reduce the effect of micro-grids (MGs) on the existing protection...
This paper presents a detailed noise and non-linearity analysis of a 10-bit 1.2Vppd 50MS/s charge-injection based SAR-ADC designed in a 65 nm low power process. Being more area-efficient in contrast to a conventional capacitor DAC, a charge-injection-cell-based DAC allows to reuse its DAC cells during binary search. Based on extensive calculations and transistorlevel simulations, the charge-injection...
When the fault occurs in the ring DC system, the fault process can be divided into the current discharge stage, the diode freewheeling stage and the steady-state phase under the AC power supply. This paper mainly studies the capacitor discharge stage. Firstly, the multi-terminal DC system is decomposed into n single-ended systems. Secondly, write the state equation of the single-ended system and solve...
This paper discuss about the investigation of 150kV capacitor voltage transformer (CVT) breakdown which is occurred simultaneously after capacitor bank disconnecting process. Analysis is performed referring to the last routine maintenance and digital fault recorder (DFR) data. Based on the analysis of both data and transient simulation analysis from the model created to represent the condition during...
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