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This paper presents a new structure of a power sharing controller for a modular based dual active bridge (DAB) DC/DC converter. The modular topology is based on input-series output-parallel (ISOP) connection of DAB modules suitable for a voltage step down application at medium voltage level. Since DAB has bi-directional power flow capability, this connection would act as its dual input-parallel output-series...
AC-DC converters are mostly used as power supplies for microelectronic systems, battery chargers, wind energy applications, electric appliances in household and dc motor drives. Switched-capacitor (SC) network based converters can be good solution to the challenges of 21st century having high voltage conversion ratio and low EMI emissions. The application of this type of converters is in microprocessor...
The increase in penetration levels of distributed generators like PV and Wind in a distribution system makes the IEEE 519 standard to be a vital aspect towards power quality. The network resonance has been described by IEEE 519 as a major contributor towards the harmonic distortion. Non-linear loads such as transformers, machines, silicon-controlled rectifiers (SCRs), solid state devices, power transistors,...
Circuit breaker (CB) installed for capacitor bank is the CB which commonly experiences the switching process due to the capacitor bank function as a voltage regulator. In closing switching process, CB encounter transient condition due to inrush current. In this paper, the simulation for studying the inrush current characteristic of capacitor bank switching in Indonesia has been performed. Simulation...
This paper discusses the active and reactive power control method for a modular multilevel converter (MMC) based grid-connected PV system. The voltage vector space analysis is performed by using average value models for the feasibility analysis of reactive power compensation (RPC). The proposed double-loop control strategy enables the PV system to handle unidirectional active power flow and bidirectional...
Voltage deviations of dc-link capacitors are the main problem of multilevel diode-clamped converters (DCC). In this paper, a novel carrier-based voltage balance method is proposed to balance the dc-link capacitors of five-level DCCs. The proposed method is characterized by injecting proper zero-sequence voltages in the modulation signals of carrier-based modulators. The effects of the injected zero-sequence...
A novel control strategy is proposed for a bidirectional multiport single phase two stage microinverter without electrolytic capacitor. The application of this converter is for power factor correction under non-linear grid tied load. The converter is composed of a triple active bridge series-resonant DC/DC converter cascaded with a voltage source inverter where a film capacitor is used in the DC-Link...
This paper presents the application of a robust nonlinear optimal controller for regulating the active and reactive power in a grid-connected three-phase inverter, which includes an LCL filter to mitigate the total harmonic distortion. The optimal control law is derived from the Hamilton-Jacobi-Bellman equation for state-dependent coefficient factorized nonlinear systems. An integral control term...
This paper presents a novel control method that enables operation of Modular Multilevel Converters under non-sinusoidal AC supply conditions based on frequency domain decomposition of supply voltages. The proposed control method enables to inject or draw near sinusoidal grid currents even during the presence of harmonic distortions in the supply voltages without the use of additional hardware filters...
This paper proposes a modular multilevel converter (MMC) topology, designed particularly for load balancing in 50 Hz railway applications. The asymmetrical character of the traction load requires higher device rating for a Double-star or Delta-connected MMC compared to a symmetrical static compensator. This is due to the symmetrizing components to rebalance the capacitor voltages in the submodules...
Modular multilevel converter (MMC) has been proved a prospective topology in high voltage and high power occasions. Hybrid MMC mixed with half-bridge (HB) and full-bridge submodules (FBSMs), which achieves a good tradeoff between power devices quantity and dc short circuit fault handling capability, attracts extensive attention. In this paper, the characteristics of SM capacitor voltage ripples are...
In this work an ac-dc-ac multilevel power converter is investigated. The developed configuration is composed of one single-phase ac-dc-ac three-leg module and two H-bridges, one of them connected in the shared part of the system to employ multilevel voltages to input and output converter, and the other one connected on the grid side for input overvoltage. The converter is employed in applications...
This paper introduces a three-phase grid-connected inverter for commercial-scale photovoltaic systems. The circuit topology combines an electrolytic-capacitor-less and ac-inductor-less active bridge with a parallel-connected PWM inverter acting as an instantaneous reactive power compensator. The active bridge, called a 120°-conduction inverter, operates at the switching frequency equal to the grid...
The negative- and zero-sequence currents of a modular multilevel converter (MMC) under imbalanced ac-grid conditions increase the maximum voltage of the submodule (SM) capacitors, which should be kept below a maximum voltage limit. This paper investigates the impact of offset pulse-width modulation (OPWM) on the capacitor voltage of the MMC under imbalanced ac-grid conditions. It is demonstrated that...
A large electrolytic capacitor is always used to provide stable DC-link voltage in single-phase to three-phase power converter. However, the large electrolytic capacitor occupies a large volume and has a short lifetime as to the home appliances. And additional PFC circuit is needed to correct the grid current. In order to settle these issues, an electrolytic capacitor-less converter system is studied...
In this paper reactive power compensation using an infinite level inverter based STATCOM is proposed. Nowadays, the society is becoming increasingly dependent on the electrical supply. New equipment's are more sensitive to power quality variations. This causes the transmission line to transfer equal or sometimes more than its capacity, which leads to overloading, voltage fluctuations etc. in the system...
This paper realizes a high power factor, high reliability, and low cost PMSM drive system with small DC-link capacitor. Compared with conventional bulky electrolytic capacitor for the regulation of DC-link voltage, a small-size film capacitor with capacitance reduction to 1% is used to realize a seneorless PMSM drive with high power factor, high reliability, and high compactness. To overcome high...
For a wireless transmission system, low efficiency is the most serious problem. Proper capacitance compensation for the system is expected to reduced reactive power and improve system efficiency. In present paper, system performances are studied and compared in two cases, no compensation and compensated by series capacitance. Then variation trend of transmission efficiency with other parameters (frequency,...
The objective of this paper is to underline the potential as well as the control advantages of the modular-multilevel high-voltage-direct-current converter (MMC-HVDC). Firstly, a brief overview of the MMC-HVDC technology is given and the detailed equivalent model for this converter is presented. Secondly, a heavy focus is applied to the control of a converter substation. Thirdly, a Matlab simulation...
The never-ending increase in energy demand across the globe requires a new approach towards efficiency in the production, distribution and consumption chain. A system that achieves minimum operational losses becomes more and more attractive. This paper tackles the energy efficiency in distribution networks by proposing an optimum allocation and sizing of capacitor banks. Using a genetic algorithm,...
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