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This paper proposes a generic pole-to-pole short-circuit fault current calculation method for dc grids. The calculation procedure begins from the simplified RLC equivalent model of a single modular multilevel converter, and then the prefault matrices and faulted matrices are established and modified to calculate the dc fault currents of all the branches. The proposed approaches are validated by comparing...
Aiming at that it is difficult to choose the value of virtual damping(VD) in passivity-based controller of the Boost converter, this paper proposes an approach which can be used to calculate and optimize the value of VD. The range of VD can be determined by constraining overshoot of the current response of Boost converter. The optimal VD can be found in the range of VD by genetic algorithm(GA) and...
The paper presents a comprehensive charge modelling approach for field-effect transistor (FET) devices. For the first time an artificial neural network (ANN) is combined with the division-by-current approach to FET charge modelling. Using this technique a large-signal charge model is extracted for a 10 W GaN device from MACOM. It is shown through measurements that excellent results may be obtained...
In high-power converters based on SiC-MOSFET half-bridge modules, laminated busbar plays a critical role in linking the DC capacitor bank to power modules. The busbar stray capacitance has the same order of magnitude with drain-source capacitance of SiC-MOSFET and has a great impact on the turn-off voltage oscillation of SiC-MOSFET. In this paper, parasitic elements of a three-layer laminated busbar...
A novel sub-module circuit is proposed in this paper based on the controllability theory. At first, traditional full bridge sub-modules (FBSM) of the MMC is modeled as a switched linear system, then controllability of the switched linear system model of the sub-module circuit is studied. It is found that the sub-module circuit is state controllable with only four operation modes adopted in the model...
Vector control is the most commonly used control strategy for modular multilevel converter (MMC) based HVDC system. However, due to the complicated structure of MMC, there is no precise mathematical model for the outer DC voltage loop. The conventional model ignores the capacitor voltage dynamics, and the AC voltage boosted operation scenario is not considered. This paper proposes a small signal model...
The purpose of this study is to design a LQR controller for the SEPIC (Single-Ended Primary-Inductor Converter) converter which is widely employed in industrial DC-DC power conversion and is also starting to see widespread use in PV applications. Circuit-Averaging-Method is used to acquire the mathematical model of the given system. Controllers are designed based on the Small-Signal model. LQR and...
Simulation of power converters is particularly necessary in the automotive industry where the requirements for rapid development and the right choice of components allow reducing design time and allowing engineers to verify by more simulations many of the preliminary versions of the electronic power schemes. In this paper we present the simulation of the back 48 to 14V converter required nowadays...
Voltage Balance of the series-connected dc-link capacitors is the key problem of three-level diode-clamped converters. In this paper, an auxiliary voltage balance circuit (VBC) is presented to maintain the voltage balance of dc-link capacitors. The voltage balance circuit consists of a clamping capacitor and a current-limiting inductor. With the clamping capacitor, the voltage stresses of the auxiliary...
The advantages of the Modular Multilevel Converter (MMC) as a Voltage Source Converter (VSC) is well known. These includes scalability, increased reliability, lower Total Harmonic Distortion (THD) in output variables, fault tolerance and so forth. The MMC has found its most application in High Voltage DC (HVDC) systems again because of the stated advantages. In the analysis of such systems, because...
Real-time simulation of modular multilevel converter (MMC)-based HVDC is one of the most important and difficult technologies in the area of power electronics research. This paper presents a methodology for the hardware in loop (HIL) CPU/FPGA-based real-time simulation of a one-terminal MMC HVDC of up to 468 levels using a detailed equivalent model, and the simulation system is based on full-scale...
As a key component of DC medium voltage breaker, the switch mechanism is required to open in high-speed and can withstand the breaking voltage which is generated during opening motion. Thus, the design of driving circuit of switch mechanism is very important to optimize the mechanism structure and improve mechanism opening characteristics. First the motion principle of high-speed switch was given...
Due to the absence of a natural current zero crossing in breaking process of a DC system, DC breakers have to dissipate the large amount of residual energy which is stored in the inductance in the system. ZnO arresters are used for switching over-voltage preventing and residual energy absorption. A dynamic simulated model of HVDC vacuum circuit breaker (VCB) with forced current zero based on PSCAD...
The specific problems of the disconnection of HVDC breakers need an analysis of performances at laboratory scale. In the study of hybrid circuit breakers with commutation, three steps are necessary: modeling, simulation and experimental tests. The paper presents a modeling procedure for a hybrid commutation breaker intended to operate using resonant circuits phenomenon. Using the Matlab platform,...
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...
This paper presents dc-dc converter based on voltage dividing class E amplifier. Class E2 dc-dc converter, which is one of the converter suitable for high operating frequency is studied. Class E2 dc-dc converter composed of a Class E amplifier and Class E rectifier. the amplifier side and rectifier side of class E2 dc-dc converter can achieve ZVS and ZDS. However, it is indicated that peak switch...
A novel Medium Voltage Direct Current (MVDC) circuit breaker consisting of a High-Speed Switch(HSS) and a bridge-type commutation branch, which is based on current injection, is proposed and analyzed in this paper. The commutation branch of this design adopts bridge type, which can break bidirectional fault current rapidly by controlling thyristors. Meanwhile, after fault current is commutated to...
This paper analyzes ratio and phase displacement errors produced by commercial capacitive voltage transformers (CVT) under non-sinusoidal waveforms, as exist in power networks. As power quality measurements in high voltage systems are performed at the low voltage side, it is relevant to know the incidence of the CVT in the results. Additionally, a preliminary proposal to compensate those errors is...
We evaluate the flying capacitor multilevel converter (FCMC) with one switched-capacitor cell under asymmetric working condition, as a highly efficient hardware realization for the virtual infinite capacitor (VIC). The VIC is a type of electronic circuit, recently introduced to replace large, expensive and unreliable electrolytic capacitors, mainly intended for smoothing random fluctuations of a DC...
Research on direct current (dc) interruption has grown in recent years, driven by increased interest in using high voltage direct current (HVDC) for large power transmission and future grids. In fact, dc interruption poses particular challenges to protection devices and circuit breakers and new technologies are needed to meet the requirements of future HVDC grids. In this paper we review some of the...
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