The modular multilevel converter (MMC) is attractive for medium- or high-power applications because of the advantages its high modularity, availability, and power quality. Reliability one most important challenges MMC consisting a large number submodules (SMs). capacitor monitoring issues in MMC. This paper proposed reference submodule (RSM)-based strategy capacitance estimation MMC, where capacitances SMs can be estimated based on voltage relationship between RSM SMs. does not rely...

Dual-active-bridge (DAB) converter is an attractive topology to be used as a dc transformer (DCT) in the power distribution system. Because voltage gain for relatively fixed, single-phase-shift (SPS) control popularly adopted DAB achieve simple control. Aiming at increasing light load efficiency of high-frequency under SPS control, this letter proposes concept full range zero-voltage-switching (ZVS) with minimum rms current certain variation range. In proposed method, added magnetizing...

The frequency-domain passivity theory offers an effective way to assess the stability of inverters connecting complex grid conditions, e.g., inductive grid, capacitive and system comprising multiple inverters. In this article, admittance model for grid-side current-controlled LCL-type inverter with capacitor voltage feedforward active damping (CVF-AD) is built facilitate passivity-based assessment controller parameter design. Especially, it found that if antiresonance frequency inverter-side...

It is a challenge for dual-active-bridge (DAB) converters to take good balance between full-load-range zero-voltage switching (ZVS) and control complexity with wide voltage range. Dual-phase-shift (DPS) can extend the ZVS range greatly compared single-phase-shift (SPS) control, it has fewer variables reduced operation modes triple-phase-shift (TPS) control. However, conventional DPS at least pair of switches will be operated under hard within large power range, which severely reduces...

In this paper, the hybrid synchronization based grid forming (HS-GFM) control and coordination strategy are proposed for inverter boost converter to provide frequency support. As main contribution, inertia power damping designed with HS-GFM between converter. The can be obtained from DC capacitor photovoltaic system in deloading mode independently. Besides, realized PV mode. After that, small signal models of considering coupling constructed simplified single input output (SISO) model guide...

Operation efficiency is one of important concerns for power conversion system. Efficiency issue microgrids with multiple paralleled inverters has been paid slightly concerns. Therefore, this article presents an analysis method microgrid in system level and efficiency-prioritized droop control strategy to improve operation under different load profiles. model first established reveal time-varying characteristic Then, optimum solution derived by Lagrange multiplier method, conditions capture...

This paper proposes a five-level active-neutral-point-clamped (5L-ANPC) dc/dc converter for applications in medium-voltage dc grids. A modulation strategy is proposed the 5L-ANPC to generate multilevel voltage waveforms, which can effectively reduce change rate dv/dt, stress on transformer, and thus electromagnetic interference increase reliability. An elimination method dead time effect also along with by employing switch series flying capacitor, eliminate high leaps caused effect. In...

It has been suggested that excessive social networking sites (SNS) users might use SNS as a method of coping with their life problems and psychosocial well-being variables interact users' motives for using in predicting problematic use. The present research explores whether the association between (i.e. self-expression passing time) usage is moderated by user's satisfaction. A total 996 college students were recruited from two colleges Chongqing China. participants divided into nonexcessive...

This article presents an enhanced hierarchical control framework of microgrids, as effective complementary conventional control, to improve operation efficiency and perform thermal management. The is implemented by two levels. In primary level, droop strategy with active management proposed identical sharing among paralleled inverters. Furthermore, secondary level developed in system-level according time-varying load profiles, where finite state machine model adopted optimize number...

A repetitive controller (RC) is one of the most promising candidates for harmonic compensation when designing current grid-connected inverters. The discrete-time closed-loop transfer function based frequency response method can be used to shape RC, which applicable a single inverter connecting well-known inductive-impedance grids, but cannot guarantee stability in case capacitive-impedance grids or complex systems, such as microgrids. To address this issue, article presents new...

With an increasing number of inverter-interfaced generators (IIGs), the power system is undergoing massive shifts toward electronic dominated system. Such paradigm change poses significant challenges to existing fault analysis theory and protection system, as a result disparate short-circuit response. Given this, needs be further investigated expanded address issues arising from new grid paradigm. Under this context, article proposes analytic model for IIGs with decoupled sequence control...

Grid-forming (GFM) control based high-voltage DC (HVDC) systems and renewable energy sources (RESs) provide support for enhancing the stability of power systems. However, interaction coordination frequency between GFM-based modular multilevel converter HVDC (MMC-HVDC) grid-following (GFL) RESs or have not been fully investigated, which are examined in this study. First, detailed AC- DC-side impedances MMC-HVDC analyzed. The impedance characteristics GFL- wind turbines next Then, influences...

This paper proposes a characteristic harmonics suppression strategy for the LCC-MMC based HVDC system using MMC. Firstly, topology of is introduced, in which sending end converter station adopts hybrid valves despite structure receiving converter. Secondly, outer voltage loop MMC, high pass filters, band and notch filters are used to extract LCC performance comparison, they reverse superimposed onto reference current. In inner current loop, PIR control proposed track compensate without...

This paper investigates a variable speed wind turbine based on permanent magnet synchronous generator and full-scale power converter in stand-alone system.An energy storage system(ESS) including battery fuel cell-electrolyzer combination is connected to the DC link of through electronics interface.Wind primary source system, FC-electrolyzer used as backup long-term system provide or absorb respectively.In this paper, control strategy proposed for operation where generator-side ESS operate...

In this paper, the input-parallel output-parallel (IPOP) three-level (TL) dc/dc converters associated with interleaving control strategy are proposed for minimizing and balancing capacitor ripple currents. The consist of two four-switch half-bridge TL featuring simple compact circuit structures, which can reduce current stresses components increase power rating converter. combination IPOP structure greatly currents on input capacitors not only by doubling frequencies these as universal...

The modular multilevel converter (MMC) is attractive for medium- or high-power applications because of the advantages its high modularity, availability, and power quality. Reliability one most important challenges MMC consisting a large number electronic devices. diode open-circuit fault in submodule (SM) an issue MMC, which would affect performance disrupt operation MMC. This paper analyzes impact failures SMs on proposes protection scheme under faults. proposed not only can effectively...

This paper presents a lifetime-oriented droop control strategy for ac islanded microgrids, which is able to perform equal thermal sharing among paralleled inverters. Electro-thermal model and temperature estimation are first established estimate characteristics of inverters, temperature-power relationships built according the electro-thermal model. Then, controller developed realize stress sharing. In addition, small-signal microgrid equipped with proposed established, effect parameters...

Aircraft passengers are more and demanding in terms of thermal comfort. But it is not yet easy for aircraft crew to control the environment system (ECS) that satisfies comfort most due a number causes. This paper adopts corrected predicted mean vote (PMV) model an adaptive assess conditions 31 investigated flights draws conclusion there does exist uncomfortable phenomenon civil cabins, especially some short-haul continental flights. It necessary develop way predict sensation direct ECS. Due...

With the development of silicon carbide (SiC) power devices, circuit structure converter for high-voltage applications would be simpler and more compact because two-level-based topologies become applicable. This paper proposes a full-bridge (FB) T-type isolated dc/dc with high input voltage wide range. The proposed is composed four main switches stress (SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> ) auxiliary low (Si )....

Current control is a crucial issue of the operation grid-connected voltage source converters (VSCs). The challenge current lies in how to track reference fast and accurate way. A second-order generalized integrators (SOGIs)-based controller one highly popular ways achieve these objectives since they can ac signals both positive negative frequencies/sequences without steady-state error. However, this may lead extra unnecessary computational burden when SOGIs are applied three-phase systems....

Distributed energy storage (DES) on the user side has two commercial modes including peak load shaving and demand management as main profit to gain profits, capital recovery generally takes 8-9 years. In order further improve return rate investment of distributed storage, this paper proposes an optimized economic operation strategy with multi-profit mode operation. Considering three management, peak-valley spread arbitrage participating in response, a model is established, proposed optimal...