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This paper presents a novel hybrid modular multilevel voltage source converter suitable for HVDC applications. It has the advantages of other modular multilevel topologies and can be made more compact making it attractive for offshore stations and city infeed applications. The Operating principle of the converter and internal energy management are discussed with simulation results from a scaled medium...
This paper presents the concept and characterization of a NPC1 phase leg built up out of three PrimePACK™ 2 power modules with .XT and 1200 V IGBT5. The target application of such a topology is 1500 V solar central inverter. After a short description of the cosmic ray reliability issues leading to the NPC1 approach, different design concepts will be discussed. Double pulse measurements have been used...
Multi-converter systems composed of series or parallel connected modular multilevel converters (MMCs) require a means to manage power sharing between the MMCs by balancing the load during operation. Series connected MMCs require proper voltage balancing while parallel connected MMCs require proper current balancing. The paper describes this imbalance phenomenon, illustrates the solution via simulation...
Current controlled inverters need to be dynamic and robust even under grid disturbances and different grid faults. Besides a robust control method the requirements for synchronization of the system become more and more important especially when multilevel inverter topologies are used. The combination of direct current control methods and advanced grid synchronization techniques promise excellent working...
This paper presents a novel resonant based, high power density power electronics converter solution for mid-feeder voltage regulation of a low voltage (LV) distribution network. Owing to the use of high switching frequency operation and a full soft-switching control strategy, the proposed converter is capable of superimposing LV compensation into the feeder voltage, to achieve a significant system...
This paper proposes a hybrid controller that combines conventional proportional-resonant controllers with the more recent application of fractional order calculus applied to the current control loop of voltage source converters. The use of existing non-integer orders applied to proportional-integral controllers is extended to resonant controllers. The application of fractional exponents for the integro-derivative...
The paper presents a detailed description of the prediction model for Predictive Power Control based on Virtual Flux (MPPC-VF) scheme for control grid connected three-level neutral-point clamped inverter (3L-NPC). The controller uses a model to calculate predictions of the future values of the virtual flux, grid currents and DC-link capacitor voltages for all possible voltage vectors. The active and...
In this paper an improved control method is proposed for space phasor based Hysteresis Current Controller. For medium voltage application, Shunt Active Power Filter (SAPF) using this improved controller will be able to meet the strict power quality standards. In a grid connected system, nonlinear loads using semiconductor devices pose a serious threat to power quality and there this proposed controller...
For modular multilevel converter, large number of switching elements introduce challenges to electromagnetic transient simulations. In order to improve the simulation efficiency, this paper proposes a two-stage modeling method of the MMC converter. The converter is represented as an extended state-space equation, which is more suitable for circulating current and control strategy studies. Then, the...
An improved circuit topology of Z-source inverter is presented that will meet the requirements and features of the Hybrid/Electric vehicle power control system. It is able to perform rectangular wave modulation for motor drive control depending on the drive condition of a motor which cannot be achieved from the conventional Z-source inverter.
This paper proposes a new interline hybrid unified power quality conditioner (IHUPQC) structure to improve the power quality of distribution feeders and to decrease the power ratings/voltages and switching losses of voltage source converters (VSCs). The IHUPQC consists of dynamic voltage restorer (DVR), an isolated dc-dc converter and a shunt hybrid active power filter (SHAPF) with a common dc bus...
Integration of power due to distributed renewable energy resources (DRERs) with the existing grid to supply electricity to both industrial and residential users is expected to have a significant impact on the future power system. Power electronic transformer (PET) has emerged as one amongst the promising technologies to achieve such requirement. In this paper, a multi-source fed power electronic transformer...
The multiplication of interfaced generation units connected to the utility grid might form VSC-based transmission grids in a near future. To support the utility grid autonomously, the converters must provide grid-forming capabilities and be connected in parallel. As the structure of a transmission grid is changing and unknown, these requirements presume a robust local voltage control for each high-power...
This paper proposes sub-module integration of a photovoltaic (PV) microinverter. It is proposed to remove the existing junction box and replace the by-pass diodes with individual DC-DC converters connected to a single-phase inverter. Particular attention is given to systems operating under long-term non-uniform conditions, such as snow or dust accumulation. A comparison with a classical two-stage...
The Modular Multilevel Converter (MMC) has enhanced the feasibility of Multi-Terminal DC grids (MTDC). For controlling the DC bus voltage in the MTDC grids, the droop control is the most promised technique. This paper evaluates the dynamic impact of the way of controlling the MMC on the MTDC grids. Results are compared with a simplified model that highlights the key elements for the dynamic behavior...
Multilevel converters (MCs) are utilized in medium voltage (MV) high power applications due to its higher efficiency than two level converters. On the other hand, modular multilevel converters (MMCs) provide several advantages with regard to other MCs, such as higher scalability, reliability and no requirement of a common DC capacitor. Particularly, low switching frequency modulations, such as (2N+1)...
For drive train efficiency estimation, three-level inverters are analyzed regarding different modulation techniques and switching frequencies. In this paper an optimized operating mode selector is proposed to choose a loss optimal modulation technique and switching frequency for each operating point. Energy savings due to the operating mode selector are validated on a driving cycle.
This paper presents the control method of an LCL filter implemented for a three-phase, voltage-source, grid-connected inverter for not only offering better attenuation of switching harmonics but also for highly damping the resonance. A discrete-time deadbeat current controller with tuned state-feedback gains is proposed to realize the time optimum responses with high control accuracy. In addition,...
In this paper two recent presented active grid current stabilisation strategies for direct matrix converter based drives with squirrel-cage asynchronous induction machines are compared with there passive counterparts. While the functionality of the active stabilisation strategies has been proven already this publication focuses on the harmonic distortion of grid and machine current as well as the...
Solid-State Power Controller (SSPC) is a key device in the advanced aircraft power distribution system. It replaces the traditional electromechanical circuit breakers, contactors and relays to switch loads on/off and provides comprehensive protection functions. The large surge current, which results from the starting of large capacitive loads, is similar to the short-circuit fault, so it may mislead...
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