Journal articles: 'Medium Voltage DC'

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Vaishnavi, Gatla, C. Venkatesh, Madikonda Rumitha, and Abhishek Shanmukhan. "Single-Input Dual-Output Three-Level DC–DC Converter for EV." International Journal of Advance Research and Innovation 10, no. 1 (2022): 48–53. http://dx.doi.org/10.51976/ijari.1012208.

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This paper presents the development of a non-isolated single-input dual-output three-level dc–dc converter (SIDO-TLC) appropriate for medium- and high-voltage applications. 3 level Buck-Boost converter is used in order to achieve the controllable output voltages. The main merits of this project include reducing voltage stress across semiconductor devices, improving efficiency, and reducing passive components size. This converter shows very good stability, even under simultaneous step changes of the loads and input voltage. Simulation analysis of converter output voltages for various duty cycles is presented for three cases of duty cycle control range.

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Kim, Minseung, Donghee Choi, and Soo Hyoung Lee. "A DCM-Based Non-Isolated Step-Down DC Transformer." Energies 17, no. 4 (February 17, 2024): 940. http://dx.doi.org/10.3390/en17040940.

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DC transformers have emerged as essential devices for medium voltage DC (MVDC)-low voltage DC (LVDC) distribution systems. However, conventional step-down single-level converters have limits on the voltage level of the MVDC-LVDC distribution system. This paper proposes a non-isolated step-down (NISD) DC transformer based on discontinuous conduction mode (DCM). The proposed structure can withstand high voltage levels by sharing voltages between energy storage modules dividing voltage levels. The proposed NISD DC transformer determines operational modes based on energy storage modules and performs the voltage conversion process. The effectiveness of the proposed NISD DC transformer is verified based on a case study using a power system computer-aided design and electromagnetic transient simulation engine including DC (PSCAD/EMTDC™).

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Du, Sixing, Bin Wu, Kai Tian, David Xu, and Navid R. Zargari. "A Novel Medium-Voltage Modular Multilevel DC–DC Converter." IEEE Transactions on Industrial Electronics 63, no. 12 (December 2016): 7939–49. http://dx.doi.org/10.1109/tie.2016.2542130.

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Afridi, Muhammad Danial. "Isolated Cascaded DAB DC-DC Converter to Boost Medium DC Voltage to HVDC." Volume 21, Issue 1 21, no. 1 (June 30, 2023): 1–6. http://dx.doi.org/10.52584/qrj.2101.01.

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The offshore wind farms typically use ac system to collect power from each generator, with the voltage increased by means of high, heavy step-up transformers. DC collection grids have also recently been taken into consideration as solution to simplify and minimize the offshore windfarm platforms. DC collection grids offer an additional method to reduce complexity of offshore windfarms. However, to increase the DC voltage for HVDC transmission requires the development of high-power and high voltage converters, which presents a technical challenge. This research makes use of an isolated cascaded dual active bridge (DAB) DC-DC converter to boost medium DC voltage to HVDC. Isolated Cascaded DAB DC-DC Converters are connected in series on the output side and in parallel on the input side to obtain a high transformation ratio and high power. The bidirectional DAB DC-DC converters cab be designed with power densities in the variability of tens to hundreds of kilowatts, depending on the components used and the switching frequency at which the converters function most effectively. The input parallel output series (IPOS) topology, 225 kV HVDC can be generated from a 5 kV MVDC input by cascading DAB DC-DC up to 30 stages. This converter family is useful due to its scalability and flexibility, since the power and voltage ratings can be increased while still using the same cells. MATLAB Simulink simulations are performed and verified the elementary operating characteristics of the system.

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Lin, Bor-Ren. "Soft Switching DC Converter for Medium Voltage Applications." Electronics 7, no. 12 (December 18, 2018): 449. http://dx.doi.org/10.3390/electronics7120449.

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A dc-dc converter with asymmetric pulse-width modulation is presented for medium voltage applications, such as three-phase ac-dc converters, dc microgrid systems, or dc traction systems. To overcome high voltage stress on primary side and high current rating on secondary side, three dc-dc circuits with primary-series secondary-parallel structure are employed in the proposed converter. Current doubler rectifiers are used on the secondary side to achieve low ripple current on output side. Asymmetric pulse-width modulation is adopted to realize soft switching operation for power switches for wide load current operation and achieve high circuit efficiency. Current balancing cells with magnetic component are used on the primary side to achieve current balance in each circuit cell. The voltage balance capacitors are also adopted on primary side to realize voltage balance of input split capacitors. Finally, the circuit performance is confirmed and verified from the experiments with a 1.44 kW prototype.

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Li, Zhenqiang, Huiwen He, Lei Wang, Le Gao, Min Zhang, and Rui Fan. "A comprehensive evaluation method of DC voltage sag in medium-low medium–low voltage DC distribution system." Energy Reports 8 (November 2022): 345–56. http://dx.doi.org/10.1016/j.egyr.2022.10.140.

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Zheng, Shaoduo, and Feng Lyu. "Compact Medium Voltage DC/DC Converter Using Series-Connected Power Devices." Electronics 9, no. 6 (June 21, 2020): 1024. http://dx.doi.org/10.3390/electronics9061024.

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Medium voltage (MV) DC/DC converters are key equipment for interconnection between DC power lines with different voltage levels in MVDC grids. The Input-series-output-parallel (ISOP) modular MV DC/DC converter is feasible to realize MV to low voltage (LV) conversion. However, a large number of LV modules in the converter may reduce the reliability and increase the complexity. This letter proposes a phase-shifted full-bridge MV DC/DC converter using series-connected power devices as switching modules. The converter is of low cost, simple structure, compact volume, and high reliability because these switching modules require only one external isolated driver circuit and very few components to achieve voltage sharing among series-connected power devices. The operation principle of the switching modules is analyzed, and the simulation and experimental results validate the feasibility of the converter design.

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Huang, Ming. "A Non-Isolated DC-DC Modular Multilevel Converter with Proposed Middle Cells." Electronics 11, no. 7 (April 2, 2022): 1135. http://dx.doi.org/10.3390/electronics11071135.

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Unlike the modular multilevel converter (MMC) topology operated under the rectifier or inverter modes, control of the balanced state for the submodule (SM) capacitor voltage has emerged as the key issue for DC-DC MMCs. This is mainly caused by no balanced alternative powers being used for balancing SM capacitor voltages, which can be absorbed from the input or output DC sides of the converter. Typically, the alternative voltages and currents should be injected to achieve SM capacitor voltage balance in the DC-DC MMC. However, this solution is based on the cost of adopting the bulky LC filter components. For interconnecting different DC voltages in medium-voltage applications, this paper presents a non-isolated DC-DC MMC equipped with the proposed middle cells. It is intended to achieve DC voltage conversion without adopting bulky passive LC filters. On the one hand, the alternative currents, used for balancing the SM capacitor voltages, are arranged for flowing only within the phase legs of the proposed DC-DC MMC without disturbing the input current. On the other hand, through appropriate control of the middle cells, compensated components can be developed to eliminate the undesirable voltages on the output DC side. The middle cells of the proposed DC-DC MMC are supplied with the function of the active filter, which enables the DC-DC MMC system to escape the bulky LC components. Through theoretical analysis and a control strategy, the proposed DC-DC MMC has been analyzed comprehensively. Finally, the simulation and experimental results are verified to evaluate the effectiveness of the proposed DC-DC MMC.

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Alsokhiry, Fahad, and Grain Philip Adam. "Multi-Port DC-DC and DC-AC Converters for Large-Scale Integration of Renewable Power Generation." Sustainability 12, no. 20 (October 13, 2020): 8440. http://dx.doi.org/10.3390/su12208440.

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Numerous research studies on high capacity DC-DC converters have been put forward in recent years, targeting multi-terminal medium-voltage direct current (MVDC) and high-voltage direct current (HVDC) systems, in which renewable power plants can be integrated at both medium-voltage (MV) and high-voltage (HV) DC and AC terminals; hence, leading to complex hybrid AC-DC systems. Multi-port converters (MPCs) offer the means to promote and accelerate renewable energy and smart grids applications due to their increased control flexibilities. In this paper, a family of MPCs is proposed in order to act as a hybrid hub at critical nodes of complex multi-terminal MVDC and HVDC grids. The proposed MPCs provide several controllable DC voltages from constant or variable DC or AC voltage sources. The theoretical analysis and operation scenarios of the proposed MPC are discussed and validated with the aid of MATLAB-SIMULINK simulations, and further corroborated using experimental results from scale down prototype. Theoretical analysis and discussions, quantitative simulations, and experimental results show that the MPCs offer high degree of control flexibilities during normal operation, including the capacity to reroute active or DC power flow between any arbitrary AC and DC terminals, and through a particular sub-converter with sufficient precision. Critical discussions of the experimental results conclude that the DC fault responses of the MPCs vary with the topology of the converter adopted in the sub-converters. It has been established that a DC fault at high-voltage DC terminal exposes sub-converters 1 and 2 to extremely high currents; therefore, converters with DC fault current control capability are required to decouple the healthy sub-converters from the faulted one and their respective fault dynamics. On the other hand, a DC fault at the low-voltage DC terminal exposes the healthy upper sub-converter to excessive voltage stresses; therefore, sub-converters with bipolar cells, which possess the capacity for controlled operation with variable and reduced DC voltage over wide range are required. In both fault causes, continued operation without interruption to power flow during DC fault is not possible due to excessive over-current or over-voltage during fault period; however, it is possible to minimize the interruption. The above findings and contributions of this work have been further elaborated in the conclusions.

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Simiyu, Patrobers, Ai Xin, Kunyu Wang, George Adwek, and Salman Salman. "Multiterminal Medium Voltage DC Distribution Network Hierarchical Control." Electronics 9, no. 3 (March 19, 2020): 506. http://dx.doi.org/10.3390/electronics9030506.

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In this research study, a multiterminal voltage source converter (VSC) medium voltage DC (MVDC) distribution network hierarchical control scheme is proposed for renewable energy (RE) integration in a co-simulation environment of MATLAB and PSCAD/EMTDC. A DC optimal power flow (DC OPF) secondary controller is created in MATLAB. In PSCAD/EMTDC, the main circuit containing the adaptive DC voltage droop with a dead band and virtual synchronous generator (VSG) based primary controller for the VSCs is implemented. The simulation of the MVDC network under the proposed hierarchical control scheme is investigated considering variations in wind and solar photovoltaic (PV) power. The network is also connected to the standard IEEE-39 bus system and the hierarchical scheme tested by assessing the effect of tripping as well as restoration of the REs. The results show that during random variations in active power such as increasing wind and PV power generation, a sudden reduction or tripping of wind and PV power, the primary controller ensures accurate active power sharing amongst the droop-based VSCs as well as regulates DC voltage deviations within the set range of 0.98–1.02 pu with an enhanced dynamic response. The DC OPF secondary control optimizes the system’s losses by 38% regularly giving optimal droop settings to the primary controllers to ensure proper active power balance and DC voltage stability. This study demonstrates that the hierarchical control strategy is effective for RE integration in the MVDC distribution network.

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Wan, Dai, Qianfan Zhou, Xujin Duan, Jiran Zhu, Junhao Li, and Hengyi Zhou. "A High-Power Density DC Converter for Medium-Voltage DC Distribution Networks." Electronics 12, no. 18 (September 21, 2023): 3975. http://dx.doi.org/10.3390/electronics12183975.

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A DC converter is the core equipment of voltage conversion and power distribution in a DC distribution network. Its operating characteristics have a profound impact on the flexible regulation of distributed resources in an active distribution network. It is challenging for the existing single-stage conversion topology to meet the requirements of distributed renewable energy connected to a multi-voltage level, medium-voltage grid. It is necessary to study the multistage transform power unit topology further, which can satisfy high reliability, high efficiency, and wide input range. This paper proposes a high-power density DC converter for medium-voltage DC networks with wide voltage levels. It adopts Buck-LLC integrated modular composition. The input ends of the high isolation resonant power unit are connected in series to provide high voltage endurance, and the output ends are connected in parallel to meet the high-power demand and achieve high-power transmission efficiency. The proposed series dual Buck-LLC resonant power unit topology can adjust the duty cycle of series dual buck circuits to meet the needs of different levels of medium-voltage DC power grids. The soft switching problem within the wide input range of all switching tubes is solved by introducing auxiliary inductors, thereby improving energy transmission efficiency. The auxiliary circuit and control parameters are optimized based on the research of each switching tube’s soft switching boundary conditions. Finally, an experimental prototype of a 6.25~7 kW power unit is designed and developed to prove the proposed topology’s feasibility and effectiveness. Great breakthroughs have been made both in theoretical research and engineering prototype development.

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Lian, Yiqing, Stephen J. Finney, Derrick Holliday, and Grain P. Adam. "Medium-voltage DC/DC converter for offshore wind collection grid." IET Renewable Power Generation 10, no. 5 (May 1, 2016): 651–60. http://dx.doi.org/10.1049/iet-rpg.2015.0376.

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Verdicchio, Andrea, Philippe Ladoux, Herve Caron, and Christian Courtois. "New Medium-Voltage DC Railway Electrification System." IEEE Transactions on Transportation Electrification 4, no. 2 (June 2018): 591–604. http://dx.doi.org/10.1109/tte.2018.2826780.

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Liang, Chonggan, Xinran Guo, Hongxing Wang, Qi Xu, Shi Liu, Yi Yang, and Zhigang Liu. "A hybrid full-bridge three-level DC-DC converter with crossing auxiliary capacitors." Journal of Physics: Conference Series 2360, no. 1 (November 1, 2022): 012026. http://dx.doi.org/10.1088/1742-6596/2360/1/012026.

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This paper presents a high-power medium-frequency hybrid full-bridge (FB) three-level (TL) DC-DC converter with crossing auxiliary capacitors. In this converter, two auxiliary capacitors are deployed between phases a and b, replacing the flying capacitor. The converter’s three-level leg switches are with low voltage stress, while the two-level leg switches are with high voltage stress. The topology and modulation method, as well as the switching characteristics of the hybrid FBTL DC-DC converter with crossing auxiliary capacitors are described. The feasibility and performance of the above-mentioned converter is validated by a laboratory prototype. Based on the mechanism analysis and experiments, the zero-voltage switching (ZVS) and zero-switching loss (ZSL) of power switches, self-balance of the clamped capacitors voltages, and the voltage self-balance of the switches in the three-level leg can be achieved.

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Ardhenta, Lunde, and Ramadhani Kurniawan Subroto. "Application of direct MRAC in PI controller for DC-DC boost converter." International Journal of Power Electronics and Drive Systems (IJPEDS) 11, no. 2 (June 1, 2020): 851. http://dx.doi.org/10.11591/ijpeds.v11.i2.pp851-858.

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Almost all electronic components require a DC power supply at present days. The needs of DC power supplies from low voltage scales, medium voltages such as generators, to high voltage scales for high voltage electricity transmission. The improvement of PI controller performances is presented in this paper. The adaptation gains improve transient response of DC-DC Boost Converter several operating conditions. Massachusetts Institute of Technology (MIT) rule is applied as an adaptive mechanism to determine the optimal control parameters in some conditions. The used adaptive control technique is Direct Model Reference Adaptive Control (MRAC), this method as able to control system in some various input voltage. The proposed method has a stable response and able to reach the model reference smoothly. However, the response of the system has instantaneously overshoot and follows the response back of model reference. The responses of proposed controller have short period of rise time, settling time, and overshoot.

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Chen, Yangfan, and Yu Zhang. "DC Transformers in DC Distribution Systems." Energies 16, no. 7 (March 26, 2023): 3031. http://dx.doi.org/10.3390/en16073031.

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With the rapid development of power electronics technology and its successful application, many demonstration projects of medium/low-voltage DC (M-LVDC) distribution systems have been constructed. The DC transformer (DCT) is the key equipment in the M-LVDC distribution system for interconnecting the MVDC and LVDC buses. In this paper, the characteristics of DCTs are summarized. The existing topologies of DCTs are analyzed, and the relevant control strategies are researched, including steady-state control, transient control, and cascaded control. The engineering application examples of DCTs are introduced by interpreting the medium and low-voltage DC distribution system demonstration project in Wujiang City, Suzhou. Finally, the challenges faced by the DCT are given, and the future development trend is predicted. This perspective provides a constructive basis for DCTs and an important reference for M-LVDC distribution systems.

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Steffen, Jonas, Sebastian Lengsfeld, Marco Jung, Bernd Ponick, Mercedes Herranz Gracia, Aristide Spagnolo, Markus Klöpzig, Klaus Schleicher, and Klaus Schäfer. "Design of a Medium Voltage Generator with DC-Cascade for High Power Wind Energy Conversion Systems." Energies 14, no. 11 (May 26, 2021): 3106. http://dx.doi.org/10.3390/en14113106.

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This paper shows a new concept to generate medium voltage (MV) in wind power application to avoid an additional transformer. Therefore, the generator must be redesigned with additional constraints and a new topology for the power rectifier system by using multiple low voltage (LV) power rectifiers connected in series and parallel to increase the DC output voltage. The combination of parallel and series connection of rectifiers is further introduced as DC-cascade. With the resulting DC-cascade, medium output voltage is achieved with low voltage rectifiers and without a bulky transformer. This approach to form a DC-cascade reduces the effort required to achieve medium DC voltage with a simple rectifier system. In this context, a suitable DC-cascade control was presented and verified with a laboratory test setup. A gearless synchronous generator, which is highly segmented so that each segment can be connected to its own power rectifier, is investigated. Due to the mixed AC and DC voltage given by the DC-cascade structure, it becomes more demanding to the design of the generator insulation, which influences the copper fill factor and the design of the cooling system. A design strategy for the overall generator design is carried out considering the new boundary conditions.

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He, Xiaokun, Renjie Hu, and Wu Chen. "A Hybrid Three-Level ZVZCS Converter for Photovoltaic Power Connecting to MVDC Collection System." Energies 15, no. 15 (July 25, 2022): 5365. http://dx.doi.org/10.3390/en15155365.

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Compared with the medium voltage ac (MVAC) collection system, the medium voltage dc (MVDC) one for renewable energy sources has many advantages. High-power dc/dc converters are one of the key stages of the MVDC collection system to boost the voltage generated by photovoltaic or wind turbine. A novel hybrid three-level dc/dc converter utilizing a blocking capacitor to realize zero-voltage zero-current-switching (ZVZCS) is proposed. A higher overall efficiency can be achieved by reducing conduction losses. Detailed experimental results on a scaled-down hardware prototype rated at 150 V/750 V/1 kW are demonstrated to verify the proposed converter performance.

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Kolahian, Pouya, Hadi Tarzamni, Amir Nikafrooz, and Mohsen Hamzeh. "Multi‐port DC–DC converter for bipolar medium voltage DC micro‐grid applications." IET Power Electronics 12, no. 7 (June 2019): 1841–49. http://dx.doi.org/10.1049/iet-pel.2018.6031.

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D.Srinivasa Rao & Dr. Anupama A. Deshpande. "DAB Based DC-DC High Frequency Link PET for Interconnecting MVDC-LVDC Grids." International Journal for Modern Trends in Science and Technology 7, no. 05 (May 27, 2021): 165–71. http://dx.doi.org/10.46501/ijmtst0705028.

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This paper proposes dual active bridge (DAB) based high frequency power electronic transformer (PET) for interconnecting medium voltage dc (MVDC) and low voltage dc (LVDC) grids for dc power distribution. The above proposed concept works on dual active phase shift principle and square wave HF modulation technique for bidirectional power transfer. Compared to the traditional dc transformer scheme, The proposed power electronic transformer (PET) can disconnect from LVDC distribution grid effectively as a dc breaker when a short circuit fault occurs in the distribution grid. The isolated DC-DC PET topology with a wide range of voltage conversion ratio is useful for High Voltage DC tapping. The DAB based on switched capacitor is connected to the medium voltage DC side and acts as an inverter. The proposed topology has the ability to transfer higher power, and lower circulating power, lower high frequency link voltage, and RMS current and peak values with the same transmission power in the MVDC side. This paper analyzes the topology, voltage and power characterization, control strategy in detail. Increase in the intermediate AC frequency will reduce the size of the transformer and other passive elements significantly in the circuit. The theoretical analysis is supported by MATLAB simulation.

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Ismail, Ali Ahmed Adam, and A. Elnady. "Design and implementation of multilevel non-isolated DC-DC converter for variable DC voltage source." International Journal of Power Electronics and Drive Systems (IJPEDS) 12, no. 2 (June 1, 2021): 994. http://dx.doi.org/10.11591/ijpeds.v12.i2.pp994-1005.

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In this paper, a non-isolated multi-level DC-DC (MLDC-DC) smooth buck converter with the LC filter is designed and analyzed. The presented topology can be used in low or medium voltage levels in several applications that use DC storage elements. The use of the proposed multilevel converter topology reduces the voltage stress across the power converter switching elements and facilitates the voltage rating of the switches. The designed LC filter for the multilevel converter is characterized by a small inductor size, which reduces the traditional bulky inductor used in the output of the traditional DC-DC converter. The reduction in the filter size is proportional to the number of the connected voltage sources, it works effectively to reduce ripple in the load currents, and it increases the voltage gain. The intensive analysis of the converter system and the experimental results show a stable operation of the proposed converter with precise output voltage.

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Liu, Jian Ye, and Jiao Ni. "Design of a High-Voltage Signal Generator Applied Flashover Fault Detection." Applied Mechanics and Materials 734 (February 2015): 930–34. http://dx.doi.org/10.4028/www.scientific.net/amm.734.930.

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For cable flashover failure, a signal generator design ideas of the NC DC high flash - DC medium voltage flash - low-voltage flash based on three pulse method, consists of three components: the DC source, medium-high pressure unit and low pressure unit. DC source adopts AC 220V power supply, after rectification, chopping booster output. The output of the DC source through an inverter and high-frequency boost get the high-voltage unit. Low unit through the high-speed switching devices and capacitor charging and discharging achieve nanosecond pulse generation. In this paper, the various aspects of the design of the system have made a detailed description and simulation research.

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ZHANG, Lu, Ying CHEN, Chen SHEN, Wei TANG, and Jun LIANG. "Coordinated voltage regulation of hybrid AC/DC medium voltage distribution networks." Journal of Modern Power Systems and Clean Energy 6, no. 3 (October 11, 2017): 463–72. http://dx.doi.org/10.1007/s40565-017-0324-x.

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Monadi, Mehdi, Catalin Gavriluta, Alvaro Luna, Jose Ignacio Candela, and Pedro Rodriguez. "Centralized Protection Strategy for Medium Voltage DC Microgrids." IEEE Transactions on Power Delivery 32, no. 1 (February 2017): 430–40. http://dx.doi.org/10.1109/tpwrd.2016.2600278.

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Wang, Li, Qianlai Zhu, Wensong Yu, and Alex Q. Huang. "A Medium-Voltage Medium-Frequency Isolated DC–DC Converter Based on 15-kV SiC MOSFETs." IEEE Journal of Emerging and Selected Topics in Power Electronics 5, no. 1 (March 2017): 100–109. http://dx.doi.org/10.1109/jestpe.2016.2639381.

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Espinosa, Eduardo, Pedro Melín, Carlos Baier, José Espinoza, and Hugo Garcés. "An Efficiency Analysis of 27 Level Single-Phase Asymmetric Inverter without Regeneration." Energies 14, no. 5 (March 7, 2021): 1459. http://dx.doi.org/10.3390/en14051459.

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For medium voltage applications, multilevel inverters are used. One of its classic topologies is the Cascaded H-Bridge, which requires isolated DC voltages to work. Depending on the DC voltage ratio used in the Cascaded H-bridge can be classified into symmetric and asymmetric. In comparison between symmetric and asymmetric inverters, the latter can generate an AC output voltage with more output voltage levels. DC voltage ratio most documented are binary and trinary. The last can generate an AC voltage of 3n = 27 levels is obtained, using n = 3 inverters in cascade and NLM modulation, which generates a flow power of the load to the inverters (regeneration). This work analyzes the semiconductor losses (switching and conduction) and the THD of the AC output voltage in function of index modulation, considering a non-regenerative modulation technique for a 27-level single-phase asymmetric inverter. To confirm the theoretical analyzes, simulation and experimental results are shown.

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Ngo, Minh Nhut, Philippe Ladoux, Jérémy Martin, and Sébastien Sanchez. "Silicium-Carbide-Based Isolated DC/DC Converter for Medium-Voltage Photovoltaic Power Plants." Energies 15, no. 3 (January 29, 2022): 1038. http://dx.doi.org/10.3390/en15031038.

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The production of large-scale photovoltaics (PVs) is becoming increasingly popular in the field of power generation; they require the construction of power plants of several hundred megawatts. Nevertheless, the construction of these PV power plants with conventional low-voltage (LV) conversion systems is not an appropriate technological path. Particularly, large cross-section cables, a high quantity of semiconductors, and the bulky layout of 50/60-Hz step-up transformers make the PV system less competitive in terms of energy efficiency and cost. To overcome these drawbacks, this paper introduces new PV plant topologies with an intermediate medium-voltage direct current (MVDC) collector that requires galvanic isolation for connecting the PV arrays. Then, the design of a power electronic transformer (PET) is proposed, implementing 1.7-kV and 3.3-kV silicium carbide (SiC) power modules. The study confirms that this converter allows the use of medium-frequency (MF) transformers with high power densities while maintaining high efficiency, which facilitates the implementation of isolated medium-voltage (MV) topologies for utility-scale PV power plants.

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Liu, Dong, Fujin Deng, and Zhe Chen. "Five-Level Active-Neutral-Point-Clamped DC/DC Converter for Medium-Voltage DC Grids." IEEE Transactions on Power Electronics 32, no. 5 (May 2017): 3402–12. http://dx.doi.org/10.1109/tpel.2016.2585618.

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Elserougi, Ahmed A., Ahmed M. Massoud, Ibrahim Abdelsalam, and Shehab Ahmed. "Self-balanced non-isolated hybrid modular DC–DC converter for medium-voltage DC grids." IET Generation, Transmission & Distribution 12, no. 15 (August 28, 2018): 3626–36. http://dx.doi.org/10.1049/iet-gtd.2017.1813.

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Vorperian, Vatche. "Synthesis of Medium Voltage dc-to-dc Converters From Low-Voltage, High-Frequency PWM Switching Converters." IEEE Transactions on Power Electronics 22, no. 5 (September 2007): 1619–35. http://dx.doi.org/10.1109/tpel.2007.904170.

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Yang, Jinggang, Jianhua Wang, Xiaokuan Jin, Shuo Li, Xiaolong Xiao, and Zaijun Wu. "Admittance Criterion of Medium-Voltage DC Distribution Power System and Corresponding Small Signal Stability Analysis." World Electric Vehicle Journal 14, no. 9 (August 28, 2023): 235. http://dx.doi.org/10.3390/wevj14090235.

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Aiming at the stability of a medium-voltage DC network based on a modular multilevel converter (MMC), this paper proposes an admittance stability criterion considering the influence of current-limiting inductors at the medium voltage side, which prevents the complex products and matrix calculations of traditional criteria. The DC admittance model DC transformers (DCTs) under different working modes are then established based on Thevenin/Norton equivalent circuit methods to analyze the stability of the DC system based on the proposed admittance stability criterion, which proves that the voltage resonance problem at the medium voltage side can be improved by adding active damping control strategies on DCTs also proves the effectiveness of the proposed stability criterion. The time-domain simulation and the hardware-in-loop simulation are then built in PLECS and RT Box to further verify the correctness of the system stability analysis and the effectiveness of the proposed admittance criterion, which provides a theoretical basis and technical reserve for the stable operation of the DC distribution power system.

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Sobanski, Piotr, Milosz Miskiewicz, Grzegorz Bujak, Marcin Szlosek, Nikolaos Oikonomou, and Kai Pietilaeinen. "Real Time Simulation of Power Electronics Medium Voltage DC-Grid Simulator." Energies 14, no. 21 (November 5, 2021): 7368. http://dx.doi.org/10.3390/en14217368.

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Power electronics medium-voltage (MV) systems must comply with the requirements defined in grid codes. These systems’ compatibility with the standards can be validated by specialized testing equipment: grid simulators. This paper presents a hardware in the loop (HiL) implementation and the simulation results of a MV multiphase DC/DC converter designed for MV DC grid emulation. By using ABB’s reliable, patented power converter hardware topology (US 10978948 B2) and by applying advanced control algorithms, the presented system can be used for special purposes, such as the emulation of fault events in a DC-grid used for the certification of other devices, or for other research goals. The presented concept of a power electronics DC-grid simulator (PEGS-DC) is characterized by high power capability and high voltage quality. In this paper, the general idea of a power electronics grid simulator applied for the testing of MV electrical systems is discussed. Then, details related to the PEGS-DC, such as its hardware topology and the applied modulation method are presented. Subsequently, the HiL setup is described. The main scope of this article focuses on model the description and presenting recorded HiL simulations.

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Lu, Zhebie, Chengmin Li, Ankang Zhu, Haoze Luo, Chushan Li, Wuhua Li, and Xiangning He. "Medium Voltage Soft-Switching DC/DC Converter With Series-Connected SiC MOSFETs." IEEE Transactions on Power Electronics 36, no. 2 (February 2021): 1451–62. http://dx.doi.org/10.1109/tpel.2020.3007225.

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Barrios, Manuel A., Víctor Cárdenas, Jose M. Sandoval, Josep M. Guerrero, and Juan C. Vasquez. "A Cascaded DC-AC-AC Grid-Tied Converter for PV Plants with AC-Link." Electronics 10, no. 4 (February 8, 2021): 409. http://dx.doi.org/10.3390/electronics10040409.

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Cascaded multilevel converters based on medium-frequency (MF) AC-links have been proposed as alternatives to the traditional low-voltage inverter, which uses a bulky low-frequency transformer step-up voltage to medium voltage (MV) levels. In this paper, a three-phase cascaded DC-AC-AC converter with AC-link for medium-voltage applications is proposed. Three stages integrate each DC-AC-AC converter (cell): a MF square voltage generator; a MF transformer with four windings; and an AC-AC converter. Then, k DC-AC-AC converters are cascaded to generate the multilevel topology. This converter’s topological structure avoids the per-phase imbalance; this simplifies the control and reduces the problem only to solve the per-cell unbalance. Two sets of simulations were performed to verify the converter’s operation (off-grid and grid-connected modes). Finally, the papers present two reduced preliminary laboratory prototypes, one validating the cascaded configuration and the other validating the three-phase configuration.

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Ma, Dajun. "Multiport AC-AC-DC Converter for SNOP With One Medium-Frequency Transformer." CPSS Transactions on Power Electronics and Applications 7, no. 4 (December 2022): 374–85. http://dx.doi.org/10.24295/cpsstpea.2022.00034.

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With the access of increased renewable energy sources, the conventional AC distribution network is hard to flexibly adjust the line voltage and power flow. Therefore, the soft normally open point (SNOP) is applied to increase the flexibility of AC distribution network. The existing converters for SNOP use many submodules (SMs) and passive components, which have the poor economy. On this basis, a multiport AC-AC-DC converter for SNOP with one medium-frequency transformer (MFT) is proposed in this paper. The proposed multiport AC-AC-DC converter is based on the back-to-back (BTB) cascaded H-bridge (CHB) converter structure, and uses several LC resonant circuits and one MFT to replace the multiple DC-DC converters in the existing BTB CHB converters. Therefore, many SMs and passive components can be saved. Moreover, the voltages at multiple AC and DC ports of proposed multiport AC-AC-DC converter are completely decoupled, and the multiple AC and DC systems can be adjusted independently. The detailed circuit structure, control principle and design procedure of multiport AC-AC-DC converter are introduced in this paper. Finally, the simulation and experimental results verify the effectiveness of multiport AC-AC-DC converter.

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Das, J. C., and R. H. Osman. "Grounding of AC and DC low-voltage and medium-voltage drive systems." IEEE Transactions on Industry Applications 34, no. 1 (1998): 205–16. http://dx.doi.org/10.1109/28.658747.

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Roy, Shalini, and Rahul Pandey. "High Conversion Ratio Converter Using Half-Bridge Sub-Modules." International Journal of Engineering Technology and Management Sciences 4, no. 5 (September 28, 2020): 110–15. http://dx.doi.org/10.46647/ijetms.2020.v04i05.020.

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An appreciable and significant assess of consideration and mindset is currently growing up for power dc-dc converters and its further more consideration is taken towards adoption of Modular-Multilevel Converters (MMC). The paper presents a transformer less MMC by the means of superior and advanced conversion ratio for higher dc-dc power conversion. This converter is being capable of utilized mutually for both the Medium Voltage Direct Current (MVDC) transmission systems and High Voltage Direct Current (HVDC) transmission systems, due to its some remarkable distinctive attributes such as modular design, scalability, consistency, tolerance of failures, larger step up and step down ratio and lowers filtering requirements. The MMC idea connects N low voltage sub-modules in sequence to produce a high voltage output. Thus there is no complex control algorithm necessary to stabilize or balance the voltages in every sub-module. Thus the simulation and analysis of a MMC design connected with stray inductances in order to reduce losses is done with an instance of 11-times stepping up ratio.

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Tapre, Pawan C., Mohan P. Thakre, Ramesh S. Pawase, Jaywant S. Thorat, Dipak J. Dahigaonkar, Rahul G. Mapari, Sunil Somnath Kadlag, and Shridhar Khule. "New control scheme for a dynamic voltage restorer based on selective harmonic injection technique with repetitive controller." Bulletin of Electrical Engineering and Informatics 13, no. 3 (June 1, 2024): 2109–21. http://dx.doi.org/10.11591/eei.v13i3.5312.

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Repetitive controller and selective harmonic injection technique (SHI) in medium and low voltage distribution networks improve dynamic voltage restorer (DVR) DC bus voltages as well as nullify power quality (PQ) problems. DVRs use sinusoidal pulse width modulation (SPWM) firing control, but DC bus use seems to be limited, affecting density, cost, and power packaging. By adding 1/6th of the 3rd harmonic waveform to the basic waveform, SPWM yields the developed model. According to the findings, 15% of DC bus usage improves and produces high voltage AC. Nevertheless, just control systems perturb PQ. The proposed controller uses feed forward and feedback to enhance transient response and justify stable zero error. 3rd third harmonic injection pulse width modulation (THIPWM) improves total harmonic distortion (THD) in the proposed scheme. Power system computer aided design (PSCAD) simulation produced high accuracy for THIPWM and repetitive controllers.

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Choi, Hyuntae, Mihai Ciobotaru, Minsoo Jang, and Vassilios G. Agelidis. "Performance of Medium-Voltage DC-Bus PV System Architecture Utilizing High-Gain DC–DC Converter." IEEE Transactions on Sustainable Energy 6, no. 2 (April 2015): 464–73. http://dx.doi.org/10.1109/tste.2014.2382690.

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ElMenshawy, Mena, and Ahmed Massoud. "Medium-Voltage DC-DC Converter Topologies for Electric Bus Fast Charging Stations: State-of-the-Art Review." Energies 15, no. 15 (July 28, 2022): 5487. http://dx.doi.org/10.3390/en15155487.

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With the expansion of E-mobility technology, the demand for Medium-Voltage (MV) Electric Buses (E-buses) charging infrastructure has significantly increased. In this regard, the effective connection of E-bus chargers to a medium voltage power grid is essential to provide fast charging and carry out multiple charging processes simultaneously. One of the main building blocks for E-bus charging is the DC-DC converter stage responsible for regulating the power flow and matching the different voltage and power levels. Accordingly, this paper presents a comprehensive review of DC-DC converter topologies applicable to MV E-bus fast charging. This review discusses and compares the basic isolated DC-DC converter topologies. In addition, the DC-DC converters are classified based on their conversion stages. Moreover, isolated DC-DC converter topologies applicable for MV E-bus fast charging applications, including Dual Active Bridge (DAB) modular-based structure converter and Modular Multilevel Converter (MMC)-based DAB, are discussed where the merits and demerits of each topology are highlighted. Moreover, this review illustrates how DAB converters are employed in different power level applications through the multimodule converter or the MMC-based DAB structure. Furthermore, the challenges and required features for MV DC-DC converter topologies are discussed.

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Xu, Yini, Zhangliang Zhai, Xiaoning Kang, Mingda Guo, and Xiuda Ma. "Coordination control of medium-voltage hybrid ac/dc distribution." Journal of Engineering 2019, no. 16 (March 1, 2019): 910–16. http://dx.doi.org/10.1049/joe.2018.8778.

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Aithal, Avinash, and Jianzhong Wu. "Operation and performance of a medium-voltage DC link." CIRED - Open Access Proceedings Journal 2017, no. 1 (October 1, 2017): 1355–58. http://dx.doi.org/10.1049/oap-cired.2017.0946.

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Zhang, Ruike, Feng Xu, Ziyue Yang, Yifei Wu, Wenbo Wu, Song Wang, Xiaoming Huang, and Hua Feng. "Analysis of different test techniques of DC circuit breaker." Journal of Physics: Conference Series 2850, no. 1 (September 1, 2024): 012002. http://dx.doi.org/10.1088/1742-6596/2850/1/012002.

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Abstract Amidst the escalating demand for energy and the proliferation of renewable energy sources, direct current (DC) systems have garnered increasing interest. As pivotal for the safety and reliability of DC systems, testing DC circuit breakers is a critical step to evaluate their performance and dependability. This study focuses on the breaking test method for medium and high-voltage DC circuit breakers. It compares and evaluates the current waveform, recovery voltage, and energy dissipation across various test circuit methodologies during the breaking process of DC circuit breakers and assesses the suitability of test methods across different voltage levels.

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Follo, Alessandra, Oscar Saborío-Romano, Elisabetta Tedeschi, and Nicolaos A. Cutululis. "Challenges in All-DC Offshore Wind Power Plants." Energies 14, no. 19 (September 23, 2021): 6057. http://dx.doi.org/10.3390/en14196057.

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As the size and distance from shore of new offshore wind power plants (OWPPs) increase, connection to shore using high-voltage (HV) direct-current (DC) technology becomes more cost-effective. Currently, every offshore wind power plant has a collection system based on medium-voltage alternating-current technology. Such systems rely on heavy and bulky low-frequency (i.e., 50 or 60 Hz) transformers: a drawback offshore, where equipment weight and space are restricted. Consequently, there is growing interest in medium-voltage direct-current collection systems, in which low-frequency transformers are replaced with DC/DC converters equipped with lighter and smaller medium-frequency transformers. However, the deployment of all-DC OWPPs still faces several challenges. Based on a very comprehensive and critical literature review, three of them are identified and discussed in this paper. The first challenge is the technological gap at component level. In this work, the DC/DC converter topologies most suitable for application to OWPPs are described and compared. The second challenge is the controllability of DC collection systems. Parallel, series and hybrid DC collection system layouts are presented and discussed. The third challenge is the compliance of all-DC OWPPs with current requirements for their connection to the onshore grids. The three challenges are discussed to highlight current research gaps and potential future directions.

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Burada, Satyanarayana, and Kottala Padma. "Model predictive current control for maximum power point tracking of voltage source inverter based grid connected photovoltaic system." International Journal of Power Electronics and Drive Systems (IJPEDS) 14, no. 3 (September 1, 2023): 1781. http://dx.doi.org/10.11591/ijpeds.v14.i3.pp1781-1790.

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Due to the high demand of grid connected photovoltaic systems, there is a need to track the maximum power point of the PV system. As the output of PV system is dc, there should be a converter, acting as medium between PV system and dc bus capacitor to track maximum power at all the loads. Usually boost converter is acting as medium between PV system and dc link capacitor as the duty cycle of the insulated-gate bipolar transistor in boost converter is in between 0 to 1 for maximum loads during maximum power point tracking (MPPT). To make PV system stable, the balance point is dc bus. If the dc bus voltage is constant, the system will be stable. Then the transfer power will just depend on current. For this purpose, the active current reference signal is to be generated by setting up the reference voltage across dc bus. Here to generate active reference current, PI controller is used and the reference voltage is taken according to the peak voltage of the inverter output voltage. The proposed control strategy was evaluated on a three-phase inverter linked to the grid and supplied by the PV system, which is working under varying irradiation conditions.

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Wang, Huan, Yu Zhou, Xinke Huang, Yibo Wang, and Honghua Xu. "Topology and Control Strategy of PV MVDC Grid-Connected Converter with LVRT Capability." Applied Sciences 11, no. 6 (March 18, 2021): 2739. http://dx.doi.org/10.3390/app11062739.

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This paper proposes an isolated buck-boost topology and control strategy for the photovoltaic (PV) medium-voltage DC (MVDC) converter with low-voltage ride through (LVRT) capability. The proposed isolated buck-boost topology operates on either boost or buck mode by only controlling the active semiconductors on the low-voltage side. Based on this topology, medium-voltage (MV) dc–dc module is able to be developed to reduce the number of modules and increase the power density in the converter, which corresponds to the first contribution. As another contribution, a LVRT method based on an LC filter for MVDC converter is proposed without additional circuit and a feedback capacitor current control method for the isolated buck-boost converter is proposed to solve the instability problem caused by the resonance spike of the LC filter. Five kV/50 kW SiC-based dc–dc modules and ±10 kV/200 kW PV MVDC converters were developed. Experiments of the converter for MVDC system in the normal and LVRT conditions are presented. The experimental results verify the effectiveness of the proposed topology and control strategy.

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Shah, Faisal Mehmood, Sarmad Maqsood, Robertas Damaševičius, and Tomas Blažauskas. "Disturbance Rejection and Control Design of MVDC Converter with Evaluation of Power Loss and Efficiency Comparison of SiC and Si Based Power Devices." Electronics 9, no. 11 (November 8, 2020): 1878. http://dx.doi.org/10.3390/electronics9111878.

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With direct current (DC) power generation from renewable sources, as well as the current relocation of loads from alternating current (AC) to DC, medium-voltage DC (MVDC) should fill gaps in the areas of distribution and transmission, thereby improving energy efficiency. The MVDC system is a platform that interconnects electric power generation renewables (solar, wind) with loads such as data centers, industrial facilities and electric vehicle (EV) charging stations (also using MVDC technology). DC–DC power converters are part of the rising technology for interconnecting future DC grids, providing good controllability, reliability and bi-directional power flow. The contribution of this work is a novel and efficient multi-port DC–DC converter topology having interconnections between two converters, three-level neutral point clamping (NPC) on the high-voltage (HV) side and two converters on the low-voltage (LV) side, providing two nominal low voltages of 400 V (constant) and 500 V (variable), respectively. The design of this new and effective control strategy on the LV side has taken into condition load disturbances, fluctuations and voltage dips. A double-closed-loop control topology is suggested, where an outside voltage control loop (in which the capacitance energies are analyzed as variable, and the inside current loop is decoupled without the precise value of boost inductance) is used. The simulation results show the effectiveness of the proposed control system. In the second part of this study, wide-bandgap SiC and Si devices are compared by using comprehensive mathematical modeling and LT-spice software. Improving power loss efficiency and overall cost comparisons are also discussed.

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Benali, Abdelkrim, Mounir Khiat, and Mouloud Denai. "Voltage profile and power quality improvement in photovoltaic farms integrated medium voltage grid using dynamic voltage restorer." International Journal of Power Electronics and Drive Systems (IJPEDS) 11, no. 3 (September 1, 2020): 1481. http://dx.doi.org/10.11591/ijpeds.v11.i3.pp1481-1490.

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In this paper, we have presented a simulation study to analyze the power quality of three phases medium voltage grid connected with distribution generation (DG) such as photovoltaic (PV) farms and its control schemes. The system uses two-stage energy conversion topology composed of a DC to DC boost converter for the extraction of maximum power available from the solar PV system based on incremental inductance technique and a three-level voltage source inverter (VSI) to connect PV farm to the power grid. To maintain the grid voltage and frequency within tolerance following disturbances such as voltage swells and sags, a fuzzy logic-based Dynamic Voltage Restorer is proposed. The role of the DVR is to protect critical loads from disturbances coming from the network. Different fault conditions scenarios are tested and the results such as voltage stability, real and reactive powers, current and power factor at the point of common coupling (PCC) are compared with and without the DVR system.

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Eya, Candidus U., Ayodeji Olalekan Salau, and Stephen Ejiofor Oti. "High Performance DC-to-AC Converter Using Snubberless H-Bridge Power Switches and an Improved DC-to-DC Converter." International Journal of Circuits, Systems and Signal Processing 15 (April 8, 2021): 315–33. http://dx.doi.org/10.46300/9106.2021.15.36.

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This paper presents the analysis, modeling, simulation, and implementation of a high performance DC-to-AC (DC-AC) converter. The system comprises of a combination of DC power source, stress less DC-to-DC (DC-DC) voltage converter, two snubberless power switches, and control unit. The system is portable, has a two-stage input voltage transformation and amplification with no transformer and occupies less space unlike the classical two-stage inverter systems. In addition, the system produces a constant DC boosted voltage with less stress on both the source and DC storage capacitor which are not found in conventional converters. The proposed power electronic converter system produced the following results: pure sine voltage and current waveforms, total harmonic distortion (THD) of 4.294%, power output of 5740W, efficiency of 98.9%, power loss of 60W and fast dynamic response. The target areas of applications of the proposed converter are in medium and small scale industries.

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Kopacz, Rafal, Michal Harasimczuk, Przemyslaw Trochimiuk, Grzegorz Wrona, and Jacek Rabkowski. "Medium Voltage Flying Capacitor DC–DC Converter With High-Frequency TCM-Q2L Control." IEEE Transactions on Power Electronics 37, no. 4 (April 2022): 4233–48. http://dx.doi.org/10.1109/tpel.2021.3122329.

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Journal articles on the topic 'Medium Voltage DC'

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