The dc–dc modular multilevel converter (dc–dc MMC) with a medium-frequency ac-link transformer is promising candidate for the modern electric ship medium voltage dc power system to provide galvanic isolation, flexible regulation, and fault ride through ability. However, steady states dynamics of such an isolated MMC are rather complicated because it contains many state variables. Moreover, on-ship requirements further complicate design. This paper thus proposes modeling control MMC. Based on...

Modular multilevel converter (MMC) can be considered as a promising candidate for modern electric ship medium-voltage direct current (MVDC) power system due to its high-voltage quality, low switching loss, good expansibility, and redundancy. As the voltage level in MVDC is much lower than that case, number of submodules (SMs) MMC also less. Therefore, SM failure will have more significant effect on safety operation. Since uninterrupted operation one most important requirements application,...

The modular-multilevel-based isolated dc–dc converter (MMDC) is an attractive solution for the interconnection of medium-voltage (MV) and low-voltage (LV) dc grids. With a modular-multilevel (MMC) on MV side full bridges (FBs) LV side, MMDC can be flexibly scaled to different voltages power ratings. However, existing limited two-port operation where dc-link powers FBs must always kept identical. This letter proposes scheme that enables fully independent three-port bidirectional capable MVDC...

For stretchable strain sensors, which have shown great application potential in human motion monitoring, it is still an enormous challenge to achieve a highly linear response range. Herein, we put forward novel carbon nanotube (CNT)/Ecoflex sensor with excellent electrical and mechanical properties, was fabricated ultrasonically assembled CNTs on Ecoflex film (UACEF) by ultrasonication evaporation form conducting network of multiwalled (MWCNTs). The UACEF sensors exhibit ultrawide range 500%...

In medium-voltage direct-current (MVDC) distribution grid, the solid-state transformer (SST) with battery energy storage system (BESS) can be used for exchange, voltage matching and port power decoupling, etc. However, when dc grid-side short-circuit fault occurs, terminal of such should have ability to prevent from large overcurrent which may violate safe operation system. This paper proposes a cost-efficient circuit breaker (SSCB) using series-connected IGBTs configured at BESS...

Due to carbon peaking and neutrality, the new distribution system for energy connection will become development direction of AC DC in future. With high penetration intermittent distributed resources flexible load, problems voltage violation fluctuation have been becoming more serious. Thus urgent need arises solve problem reactive power optimization system. In this paper, multi-resolution model definition its background are presented at first. Secondly, a is proposed analyse dynamic...

A miniaturized microstrip dual-mode filter with different responses is developed in this letter. coupling and routing scheme presented to model the operations of filter. The new reduces occupied area up 33% compared conventional one at 1.89 GHz. Meanwhile, proposed circuit enables second harmonic response be effectively suppressed. demonstrator designed validated good agreement between full-wave electromagnetic simulations measurements.

The key technology of a cascaded multilevel inverter with hybrid energy sources lies in the power distribution among different chains. A control strategy between storage elements and capacitors is proposed to achieve fault tolerant control. In sources, chains can operate four quadrants, while only two quadrants. With method, active realized by voltage vector superposition, reactive achieved initial operation point selection. This enhances both system reliability availability enabling...

To maintain the safe and stable operation of power system with interconnection distributed generation (DG), urgent need arises to determine maximum penetration level DG. Voltage fluctuation, which is especially affected by stochastic nature renewable load, has a significant impact on DG penetration. Thus in this study two‐dimensional multi‐resolution model, can demonstrate load voltage proposed. Then an analytical methodology based proposed model presented level, without violating limits...

The applications of the modular multilevel converter (MMC) have been expanded to medium-voltage fields in recent years, and diagnosis submodule faults is a crucial issue for system reliability. fault MMC usually realized by software methods cost-effective purpose. However, most are based on complicated models require two operational steps (i.e., detection step localization step), thus time-consuming. To address this issue, paper proposes fast method where each associated with first-order...

Line fault is the most important factor which affects reliability of power supply in distribution network. After failure, it needed to find cause quickly and accurately, will eliminate potential safety hazard for grid operation from source reduce probability effectively. At present, analysis always depends on human experience, lack scientific quantitative basis poor time effectiveness. This paper mines out gradational structure space-lime law historical records proposes a line-fault method...

Two medium voltage direct current (MVDC) grids can be connected via an isolated DC–DC modular multilevel converter (DC–DC MMC) to enhance the power transmission and supporting abilities. DC power, terminal currents, arm energy balancing active/reactive through inner AC link need controlled in such a MMC, submodule grid fault situations should also addressed. Therefore, multi-object controller is inherently required. This study thus proposes control frame that realise not only regulation but...

DC–DC modular multilevel converter (DC–DC MMC) is an attractive candidate for high-voltage DC (HVDC) interconnections since it can provide the required voltage matching, galvanic isolation and flexible power control abilities. The semiconductor loss of such a MMC major concern both system evaluation parameter design. However, cannot be measured directly out precision range measuring equipment, thus, mathematical analysis considered as feasible alternative. This paper proposes accurate...

A new islanding boundary searching approach based on slow coherency and graph theoretic is presented in this paper. During system Oscillation, generator groups are identified by criterion firstly. Then after simplified, the multilevel k-way partition algorithm adopted to compute best point. Finally, case analysis proves that strategy available for avoiding blackouts.

This paper mainly focuses on the future transmission technologies trend, such as regular long-distance technology UHV AC and DC technology, flexible HVDC, grid, high-T_c superconductors DC, half wave-length transmission, Gas Insulated Line technology. The maturity assessment method is applied to evaluate development of at different stage. Based analysis trend electric power three Asia grids interconnection modes are proposed, which synchronous HVDC supply grid. relationship between grid...

Based on power law fluid flow parameters in pipelines from analytical deduce, the mechanism of commonly used polymer drilling can be analyzed. The calculation results will compared with ordinary Newtonian fluid's and verified by indoor experiment data application data. Through MATLAB, relationship Power- between pressure drop (dp / dl) (Q) velocity distribution calculated. show that analysis Power-law to strong chip drag reduction is more line actual situation it deeply reveal has superior...

Regarding the coordinated dispatch of active power distribution network containing large-scaled distributed generations (DGs) and electric vehicles (EVs), this paper proposes a method based on voltage iteration. A model for that can optimize node charging EVs output DGs is established. Then loss in optimization objective simplified by static which obtained previous Meanwhile, nonlinear restrictions between are sensitivity equation, also voltage. Finally, an iteration proposed to correct used...

According to the development of UHVDC and MTDC technology, cascade-connected MT-UHVDC system is presented. This paper introduces characteristics this kind system, including electric structure requirements for equipments control its application in power system. Based on new transmission solution, with planning projects China future, demonstration project selected by analysis comparison, which considering problems load distribution short circuit current level stability engineering cost so on.