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In order to achieve high-quality, high-dynamic power amplification a method is proposed to split and process the current ripple independently from the main bulk current. As a consequence, low-power switching circuits with reduced stress, so-called basic crossover correction cells, can be effectively applied. Comparisons are presented to validate the proposals.
Microinverters connect a single photovoltaic (PV) module to the grid, and therefore require a high voltage step-up conversion ratio. This is usually achieved in a two-stage approach with a step-up dc-dc converter followed by a step-down inverter. More recently single-stage step-up inverters have been proposed under the assumption that less stages improves efficiency. This paper compares these two...
Power system restoration takes place where power systems experience a blackout and might be splitted into several islands with limited number of black start units. The main challenge of the restoration process is to keep both frequency and voltage within allowable limits while restoring the network through energizing lines and transformers as well as load pickup. The load pickup scheme is determined...
A Power Hardware in the Loop (FHIL) platform implementation for performing real time simulations of electric systems is proposed. The test bench consists of a FSS'®E real time power flow calculation in combination with a controlled grid emulator. Experimental results are presented to demonstrate the performance of the platform.
This paper presents the possibility of using a point-to-point voltage source converter — high voltage direct current (VSC-HVDC) transmission system connecting offshore wind power plant (WPP) to the onshore grid as black start unit to initiate the restoration process for an interconnected electrical system after a large area system blackout. The onshore converter station (CS) provides voltage in order...
Modular Multilevel Converter (MMC) has served as a promising Voltage Source Converter (VSC) for High Voltage Direct Current (HVDC) applications. In this paper, a new MMC Submodule (SM) topology called Modified Switched Capacitor Sub-Module (MSCSM) is proposed. The MSCSM is able to block the DC fault using the power electronics semiconductor diodes due to its intelligent configuration without the need...
It is known that power electronic voltage source converters are non-ideal. This paper presents a state-of-the-art review on the effect of semiconductor voltage drop on the output voltage spectrum, using single-phase H-bridge two-level converter topology with natural sampled pulse width modulation. The paper describes the analysis of output voltage spectrum, when the semiconductor voltage drop is added...
In future high-voltage direct current (HVDC) systems, a large number of HVDC breakers will be required. In this paper, the influence of HVDC breakers on the transient performance of point-to-point HVDC links in both asymmetrical and symmetrical monopolar configuration with half-bridge modular multilevel converters is studied with simulations in PSCAD. As HVDC breakers, the active resonant breaker...
An investigation of the voltage imbalance of the two capacitors of the semi-full-bridge submodule is performed. Since the capacitances are not exactly the same, there may be a difference between the capacitor voltages. The resulting current-spike when they are connected in parallel has been analyzed in a full-scale laboratory experiment.
This paper presents the method of current higher harmonics control for grid connected power electronic converter by means of a digital comb filter application. The proposed method provides multiple harmonics compensation and simple implementation. The Proportional-Resonant (PR) control was complemented with appropriately tuned comb filter which resulted in reduced mitigation of output current harmonics...
This document describes a predictive controller specifically designed to trade-off DC bus voltage regulation error, reactive power compensation and active power curtailment during abnormal operating conditions. The controller proposed evaluates different curtailment alternatives during grid faults and applies the optimal control action that enhances the system performance.
The Current-Direction Detection based on measurement of the load current can be used as static MOS-Control of the BIGT. As the gate-emitter voltage vge affects the ON-state characteristics of the BIGT in diode forward-conduction mode, it has to be adapted for optimised operation. In order to operate at low static losses vge has to be below threshold voltage in diode forward-conduction mode. The chosen...
This paper compares the design and performance of two controls for half-bridge converters with LCL output filters based on Virtual Circuit Design method, which is an intuitive way to achieve desired closed-loop behaviours as well as resonance damping and low-frequency behaviours. The first control is represented by a circuit employing a resistor in series with a converter-side inductor to stabilize...
Fault-tolerant multilevel inverters outperform known fault-tolerant 2-level inverters regarding efficiency and power density. The most promising fault-tolerant multilevel inverters for system voltages below 2 kV are the flying capacitor and the active neutral point clamped type. They differ regarding required voltage overrating of semiconductors, tolerance for open and short-on failure types and maximum...
This paper presents designing procedure of a high efficiency 5 kW silicon-carbide (SiC) based three-phase power factor correction (PFC). SiC switches present low capacitive switching loss compared to the alternative Si switches. Therefore, the switching frequency can be increased and hence the size of the line filter (generally reactive components) will be reduced. However, to achieve high efficiency...
Power electronic converters are today an essential part of the electrical power systems, employed to improve the system performance and enhance its stability. At the same time, the introduction of power converters might negatively affect the overall dynamic behaviour of the power system. System stability can be investigated from different perspectives, e.g. time-domain observation, eigenvalue analysis,...
Continuous voltage compensator was developed to improve power quality issues of distribution lines. It consists of series and shunt transformer connected through static power converters. In this paper, the compensation methods using series and shunt converters were investigated, and manufacturing of actual rating 6.6kV 3MVA prototype was reported.
The stability of grid-connected modular multilevel converter (MMC) under two control strategies is studied in this paper. For this purpose, the ac-side input admittance of the MMC is derived under open- and closed-loop ac-side control strategies. The derived analytical models are used to investigate the impact of the two approaches on the stability of the MMC and detailed time-domain simulations are...
This paper presents an effective pulse width modulation algorithm for four-leg three-level Neutral-Point-Clamped Voltage Source Converters. The proposed method is based on natural coordinates abc and can be used in three-or four-leg converters. The algorithm is characterized by simplicity and the lack of a coordinate system transformation. The method was verified by simulations and experiments using...
DC/DC converters are necessary in HVDC networks to adapt different voltage levels, different configurations or to participate in power flow control. This paper focuses on a recent DC/DC converter topology, called Modular Multilevel DC Converter (M2DC), which uses direct DC/DC connection without galvanic separations. A general analysis of the topology is firstly discussed. Afterwards a decoupled mathematical...
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