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Breakthroughs in power electronics devices enabled the utilization of the IGBT as the main power switch in AFE converters and enabled the emergence of the fully controlled Active Front End, “AFE”, and low input harmonic solution. This solution employs voltage and current control loops and switching with relatively high switching frequencies of greater than 2 KHz in most applications. The AFE converter...
This paper investigates energy storage configuration strategy for virtual synchronous machine (VSM). The proposed VSM provides virtual inertia and damping to maintain stability of grid. Virtual inertia and damping need to be established by energy storage system (ESS). So that a strategy of energy storage configuration has been investigated through theoretical analysis and simulations in this paper...
Digital control system usually introduces a beat of delay, which includes PWM upload delay and zero-order holder delay. The delay not only reduces the system phase margin, but also changes the impedance characteristics of active damping, which influences the system minimum phase property and threatens the stability of the injected current. In this paper, a PWM real-time upload method and the detailed...
This paper addresses the stability problems of a high power converter connected to a weak grid. The wide range values that grid impedance can take, challenges the stability and the performance of the controllers, which are responsible of regulating the current injection in such converters. In this work, a control strategy based on stationary reference frame controllers is selected and implemented...
This paper develops the N-paralleled converters with LCL filter system model and expands the virtual resistor control method for harmonic current control. Power electronic converter can be controlled as a current source. For some application the current source can be used to test the inductor characteristic, such as temperature rise, noise or vibration. While in some cases, several converters are...
Active damper is a promising solution to address the stability issues caused by the interaction between the parallel grid-connected converters, which are the results from the coupled grid impedance. To further improve that, this paper proposes a series active damper with closed-loop control. Unlike existing parallel active dampers that using a virtual damping resistance through detection and resonant...
This paper presents a monolithic multilevel converter realized in a depletion-mode GaN process and intended to operate as a drain supply modulator (DSM) for high efficiency radio-frequency (RF) power amplifiers (PAs). The custom prototype chip includes a four-level power stage with on-chip integrated gate drivers and damping networks designed to mitigate effects of parasitics during output voltage...
A novel practical virtual synchronous generator control strategy considering the differences between inverters and real synchronous generators is proposed in this paper. The proposed control strategy improves the emulation method of damping power in swing equation, which does not need a PLL and in the meanwhile eliminates the effect on the droop coefficient caused by the traditional constant damping...
For the LCL-filtered grid-connected inverter, it has been reported that the digital time delays will narrow the stable region of current control loop when the inverter-side current is used for implementing the feedback control. A sufficient stable condition is that the filter resonance frequency should be designed under one-sixth of sampling frequency. However, the low resonance frequency leads to...
With the increasing penetration of nonlinear loads into distribution system, stable operation of power distribution system suffers challenge by harmonic voltage propagation and resonance amplification which is also known as whack-a-mole phenomenon. However, until now this phenomenon has not been well investigated and discussed. This paper starts from theoretical analysis of harmonic propagation and...
Advances in switching power electronic converter technology have brought about a resurgence of interest in the use of DC power distribution systems for a variety of applications. However, the notional power electronic based DC distribution system is a complex and extensively interconnected system consisting of multiple power converters. A number of system-level challenges related to stability arise...
This paper presents a structured design method for half-bridge converters with higher-order lossless output filters, focusing on the popular LCL filters. The method builds on the theory of terminated ladder networks and on a control algorithm actively emulating the ladder network's termination. Given a desired transfer function, a normalized ladder network is accordingly synthesized and scaled to...
The indirect matrix converters (IMC) offer the advantages of high reliability and compactness in structure due to no large energy storage components in virtual DC side, and thus have a promising application in the future. However, the LC resonance caused by input filter is one reason keeps it from being utilized in industry. Different from pervious solutions of LC resonance damping for single IMC,...
A maximum-power-point tracking (MPPT) algorithm is essential in all controllers of solar power electronic converters due to the nonlinear current-voltage characteristics of a photovoltaic generator. One of the most widely utilized algorithms are perturbative MPPT techniques such as perturb and observe and incremental conductance methods due to their simple implementation with relatively good tracking...
High voltage dc (HVDC) systems act as the prevailed solution for transmitting offshore wind energy to onshore main grids. Control of the voltage source converters (VSC) in HVDC systems is decisive for the performance. This paper proposes the control of VSC-HVDC with electromechanical characteristics and unified primary strategy, as a reaction to the updated requirements of the ac grid transmission...
Grid-connected Voltage Source Inverter (VSI) with LCL filters, controlled by proportional-resonant compensator in αβ frame, is very popular in utility application for its better power quality feature, while the inherent LCL resonance characteristic limits the control loop bandwidth and threatens the system stability. The active damping is essential to dampen the LCL resonance. This paper investigates...
An active damping method for Thomson coil actuated ultra-fast mechanical switches is proposed, including its control. Ultra fast mechanical switches are crucial for both DC and AC circuit breakers that require fast-acting, current-limiting capabilities. However, fast motion means high velocity at the end of travel, resulting in over-travel, bounce, fatigue, and other undesirable effects. The active...
Grid-connected converters with primary frequency control and inertia emulation have emerged and are promising for future renewable generation plants because of the contribution in power system stabilization. This paper gives a synchronous active power control solution for grid-connected converters. As design considerations, the virtual angle stability and transient response are both analyzed, and...
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