The usage of too many sizeable capacitors significantly increases the volume and cost modular multilevel converter (MMC), limits its spread in medium- high-voltage applications. By adding a buck-type active power filter (APF) circuit into particular MMC topology [of which each phase multiplexes one submodule (SM)], modified (APF-M3C) topology, inherently has ability to suppress capacitor voltage fluctuations decrease losses compared with conventional is proposed this article. Both SM...

Modular multilevel converter (MMC) topology has been widely used in the medium-/high-voltage applications. However, large capacitance is needed to suppress submodule (SM) capacitor voltage ripples. This article presents a modified MMC with active power filter (APF-MMC) paralleled between Nth SM of upper arm and first lower each phase without changing original topology. It intended decrease fluctuations losses SMs by diverting low-frequency ripple powers into storage additional circuit. Both...

The modular multilevel converter (MMC) topology has been widely used in medium/high voltage high-power transmission and distribution motor drive fields. full-bridge submodule (FB-SM) MMC with fault handling capability is currently receiving increasing attention application. However, order to suppress the SM capacitor ripple, usage of capacitors larger capacitance significantly increases hardware cost volume system. In this paper, a modified FB-SM active power decoupling circuit (APD-SM)...

Modular multilevel converter (MMC) is a novel circuit that has appeared in the last few decades, and been extensively applied to medium/high voltage scenarios, especially motor drive owing its scalability easy supply higher number of output levels. As theoretical analysis shows, sub-module (SM) capacitor magnitude positively related current amplitude conversely connected fundamental frequency. Therefore, prime challenge applying MMC variable speed drives there huge oscillation SM during...

The accuracy about short-term wind speed prediction is helpful to the economy and safety in power grid. In view that nonlinear complexity characteristics related change, a new approach for forecasting put forward. proposed method belongs back propagation (BP) neural network based on improved artificial bee colony algorithm (ABC-BP). Some factors such as historical moment of speed, current air pressure temperature are all model input. weight threshold values BP optimized by using algorithm....

With the development of power electronic technologies and distributed generation, DC distribution networks attract increasing attention due to their various advantages compared with traditional AC networks. However, fault protection is one major issues in To improve reliability protect semiconductor devices under faults, a current-limiting energy-transferring circuit breaker topology proposed this paper. By applying passive components thyristors, capable quickly limiting current transferring...

Multi-terminal flexible high-voltage-direct-current (HVDC) transmission and DC grid technology are developing rapidly, the hybrid circuit breaker (DCCB) is usually used to protect system, which can quickly remove fault current make sure safe stable work of system. However, existing DCCBs have restrictions regarding one or more following characteristics: economy, fast adaptive reclosing, low on-state losses, no additional pre-charge power source. This paper presents an economical DCCB with...

This paper investigates the influence of winding configurations on core flux density harmonics axial modular switching permanent magnet (AM-FSPM) and conventional FSPM machine. The relationships between air-gap stator-rotor AM-FSPM machine with toroidal concentrated are derived based magnetic field modulation theory. Then, loss production mechanism two machines is revealed. Moreover, armature reaction harmonic amplitude ratio proposed to represent output torque machines. Thus, efficiency...

Since the DC current has no zero-crossing in high-voltage and large-capacity scenarios, low line impedance results a large growth rate of fault current, breaking requirements circuit breakers (DCCB) are further increased. Hybrid breaker (HCB) represent techniques orientation interruptions HCB can quickly interrupt currents to ensure reliable safe operation grid, which is an indispensable piece equipment flexible systems. Utilizing characteristics thyristor with strong capacity, on-state loss...

In this article, a centralized locating strategy of fault current limiter (FCL) in high-voltage direct (HVdc) grid is proposed and analyzed. By employing FCLs at the output sides modular-multilevel-converters (MMCs), could reduce number multiterminal (MTdc) grid. A typical application scenario based on Zhangbei–Beijing four-terminal HVdc introduced article. Mathematical model built numerical solutions are calculated. Then, simulation PSCAD/EMTDC different strategies FCL studied. Simulation...

Modular multilevel converters (MMC) are widely applied in HVDC projects. To ensure that MMC works properly, sub-module (SM) capacitor voltages must be balanced. This paper proposes a voltage balancing method, which alternates the driving signals on IGBTs of SMs fundamental period or carrier period, to balance voltages. Under normal operating conditions, this proposed method doesn't need and arm currents information, therefore it effectively decreases hardware cost software complexity system,...

DC circuit breaker is an important equipment to ensure the safety and stability of transmission system. It can quickly reliably cut off fault current in system maintain normal operation This paper presents a novel hybrid topology with limiting capability (CL-HCB), which composed main branch handling branch. When faults, inductor input suppress rise rate reduce amplitude current. In addition, has functions self-charging pre-charge capacitor adaptive reclosing. introduces structure working...

Phase-shifted full-bridge (PSFB) converter is widely used in high efficiency and power topologies due to its soft switching characteristics. However, the traditional PSFB difficult realize of lagging-leg switches under light load, has shortcomings such as circulating current, duty cycle loss, secondary parasitic oscillation. The shortcoming hinders frequency converter. In view PSFB, this article proposes an improved topology, which uses a four-winding transformer auxiliary circuit transfer...

Under disaster condition, emergency diesel generators play an important role in ensuring power supply and relief. The state of the AC bus under island is determined by output characteristics distributed (DGs). improved drooping method proposed paper introduces PI-based non-communication secondary control based on traditional droop to achieve stability frequency voltage condition. On basis coordinating DGs equal-distribution active power, it also possible maintain rated well system...

The circulating current of modular multilevel converter (MMC) is an inherent phenomenon. existing analysis methods have mainly considered the power losses and submodule (SM) capacitor voltage. Under low-frequency operation, MMC SM has a larger voltage ripple, this paper proposes novel injection method to reduce ripple. based on injecting current, which easily derived by instantaneous information MMC, within phase attenuate lower frequency arm powers. And, it omits using extensive lookup...

Abstract Multi‐terminal flexible high‐voltage direct current (HVDC) transmission and DC grid technology are developing rapidly. The hybrid circuit breaker (HCB) has broad application prospects in the field of HVDC power grid. Nevertheless, existing HCBs have one or more following blemishes: arc suppression scheme mechanical switch, high cost unreliable adaptive reclosure. In this paper, a modified thyristor‐based with short arcing capacity (SA‐HCB) is introduced, which consists main branch,...

The modular multilevel converter (MMC) topology is widely employed in the HVDC grid and HVAC grid. To reduce number of sub-modules (SMs), a new MMC (N-MMC)is considered. However, its special leads to more complicated startup scheme modulation strategy than that traditional MMC. deal with this issue, novel modified carrier phase-shifted SPWM (MCPS-SPWM)strategy for N-MMC are proposed analyzed. Simulation experimental results from inverter provided verify feasibility availability strategy.

Abstract In this paper, a control method combined with variable frequency and phase shifting is proposed, the primary purpose of which to optimize operating efficiency phase‐shift full‐bridge (PSFB) DC‐DC converter. By modeling losses PSFB converter, optimal switching related load conditions found. A neural network aided controller that can work linearly built achieve proposed method. At same time, voltage loop retained ensure stability output necessary dynamic response This paper builds an...