In this paper, the influence of one-sample delay for sampling and computation in digital control on bandwidth inner current loop a 400-Hz ground power unit (GPU) is analyzed first. The results show that it difficult even impossible high-power GPUs to maintain low total harmonic distortion content output voltage with conventional proportional-integral-based double-loop control. To improve performance, resonant controllers parallel structure which are widely used active filters applied...

This letter focuses on the power module (PM) capacitor voltage balancing of a $\pm 350$ -kV/1000-MW modular multilevel converter (MMC). For this MMC, current flowing through IGBTs will exceed nominal adopted commercial high-voltage (3.3 kV or higher) IGBT products, i.e., 1500 A. As for PM switching frequency must be kept low to reduce losses and accurate calculation is great importance design cooling system. presented low-switching method by introducing adjusting number (BAN). The also with...

In this paper, a novel single-phase five-level inverter is proposed using coupled inductors. This can output voltage with only one dc source. No split of the capacitor needed, totally avoiding balancing problem in conventional multilevel inverters. The level half dc-link all conditions, leading to much reduced dv/dt . based on widely used three-arm power module and stresses switches are same, making it very easy construct. Operation mechanism analyzed possible switching patterns...

Smart energy router (SER), also called as power electronics transformer (PET) or solid state (SST), will serve a critical component in the next-generation electric system. Taking advantage of modular multilevel converter (MMC) and input series output parallel (ISOP) topologies, new type smart has been developed. Presented architecture using two stages with AC/DC conversion medium-voltage (MV) side, ISOP DC/DC low-voltage (LV) thus allows interaction DC grid local renewable sources, etc....

Cascaded H-bridge (CHB) -based solid-state transformer (SST) consists of CHBs and dual active bridge (DAB) converters. Series-resonant DAB converters (SRCs) are widely used for its advantages soft switching characteristic simple control. However, the high-frequency-link (HFL) currents SRCs contain double-line-frequency harmonic fluctuation in three-phase CHB-based SST, resulting high current stress. In this article, SRC is substituted with dc terminal dynamic equivalent circuit, analytical...

Due to the power interaction between phase-shifted dual active bridges (PSDABs) and series resonant (SRDABs) in hybrid modular dc Transformer (HMDCT), it is difficulty optimize current stress based on transferred power. An extended-state-observer model predictive control (ESO-MPC) strategy with extended phase shift (EPS) proposed of PSDABs HMDCT. The MPC employed calculate optimal PSDABs. Moreover, a first-order ESO introduced observe uncertain output Based calculated power, duty ratios each...

A decentralized control method for power module (PM) capacitor voltage and switching frequency balancing in modular multilevel converter is presented this paper. The proposed composed of a central controller, six arm controllers, several group controllers. controller only charge the PM within corresponding group, among groups an arm. based on PI using average each to keep proposed. dynamically adjusted extra exchange number strategy difference also developed balance groups. key advantages...

This paper analyzes the characteristics of submodule (SM) voltage fundamental frequency and second-order harmonic ripples with consideration negative state full-bridge SM. The optimal operation point, which minimizes ripples, is derived. Both design principle analytical expressions for SM capacitance dimensioning are presented, comparison between energy storage requirements without states in arm reference voltages also carried out under same constraints on transmission power, modulation...

DC transformer (DCT) which is composed of dual active bridge (DAB) converters, capable fulfiling high-ratio voltage conversion between the medium-voltage dc distribution and low-voltage distribution. A model predictive control (MPC) strategy was proposed for DAB-DCT to improve dynamic performance achieve a proper power distribution, considering bidirectional DCT. The traditional closed-loop scheme with single-phase shift (SPS) MPC SPS are compared on downscale laboratory prototype, using...

This paper conducts a thorough analysis on the circuit dynamics of single-phase direct ac-ac modular multilevel converter (MMC) to address branch energy divergence problem in railway power conditioning application scenario. Based analysis, full degree freedom (DOF) based control scheme is proposed. By controlling all DOFs coordinated manner, extended controllability can be achieved, which enables each branch's regulated individually without deteriorating terminal currents. As result,...

This paper introduces a single-phase five-branch direct ac-ac modular multilevel converter (MMC) with the capability of equal frequency conversion for railway power conditioning applications. By analyzing branch energy balance mechanism, basic operating principle proposed MMC is clarified and control strategy also proposed. Comparisons between traditional matrix (MMMC) on voltage current ratings as well capacitor dimension requirements are presented. The effectiveness topology validated...

In this paper, a new single-phase five-level inverter is presented using coupled inductors. This can output voltage with only one dc source and no split of the capacitor needed, totally avoiding balancing problem. What more, as based on widely used three-arm power module, it very easy to construct. Operation mechanism analyzed possible switching patterns are investigated. Based these analyses, rules for optimizing modulation schemes also presented. Following rules, component will exist in...

Cascaded H-bridge multilevel converter(CHBC) has become a highly attractive topology in high-voltage and large-capacity energy storage system(ESS). In cascaded converter(CHB-ESC), elements(ESEs) such as batteries supercapacitors are distributed each power sub-module(PM), the balancing among ESEs is of great importance. two-stage CHB-ESC, voltage DC-link capacitors should be met simultaneously. Due to limitation charging discharging current ESEs, large on AC side high-power applications will...

This paper deals with parallel operation of 400Hz inverters in ground power units (GPU) for airplanes. For high-power 400-Hz inverters, the modulation frequency ratio is fairly low, which causes difficulties to operation. To reach low THD content output voltage, resonant controllers are used control each inverter paralleled GPUs. With controllers, very small phase difference between may cause huge circulating current because impedance rather low. As known, conventional droop method has trade...

The high-capacity modular multilevel converter (MMC) is becoming the most popular type of voltage-source converters for high voltage direct current (HVDC) transmission. However, nonlinearity loss characteristics switching devices and complexity patterns impose great challenge on modeling MMC. present methods still have some flaws in modulation calculation. This paper proposes a simplified MMC mathematical model based RMS average value arm current. analytical expressions this are also...

In order to reduce the cost of high voltage direct current (HVDC) transmission system, a hybrid HVDC system adopting line commutated converter (LCC) on rectifier side and dual phase shift pulse width modulated source converters (PWM -CSCs) inverter is proposed in this paper. The mathematical model output ac harmonic characteristics PWM -CSC are analyzed detail. A maximum power factor control method proposed. Finally, 400 kV/1250 MW PWM-CSC based unipolar built using PSCAD/EMTDC software....

As new electric power conversion equipment, a multi-port electronic transformer (MP-PET), including converter, high-frequency transformer, and multiple ac or dc interconnection interfaces, has broad application in the hybrid distribution network. However, high integration large number of energy storage devices led to very high-order model system. To address this issue, reduced-order small signal MP-PET is established paper. By taking participation factors system mode state variables, derived...

Based on modular multilevel converter (MMC) for high voltage direct current (HVDC) system, the startup strategy is researched. The equivalent charging circuits and physical models uncontrolled controlled process of MMC-HVDC system are derived stresses analyzed. In traditional methods, series resistors in arm or dc lines used to limit surge when MMC station unlocked at charge step from side. this paper, new method without extra source proposed. With method, side stage minimized. Experimental...

Real-time simulation of modular multilevel converter (MMC)-based HVDC is one the most important and difficult technologies in area power electronics research. This paper presents a methodology for hardware loop (HIL) CPU/FPGA-based real-time one-terminal MMC up to 468 levels using detailed equivalent model, system based on full-scale physical control system, including actual sub module boards. The testing subject accompanying are same symmetric structure, without expensive third part HIL...

This paper proposes a new derived state-space dynamic equivalent model of active distribution networks for transient analysis. The proposed model, in form six-order state space, takes the advantage simplification and less input variables, which is easy to integrate into different simulation tools.The validated under test cases. Results show that retails performance fully modeled networks.

In this paper, a hot-standby redundant design and its control strategy are proposed for hybrid dual active bridges (HyDABs) based DC Transformer (DCT). This configuration of DCT is characterized with two types isolated dc-dc converter, phase-shifted DAB (PSDAB) series-resonant (SRDAB). To achieve high reliability SRDABs, several controllable PSDABs connected SRDABs in parallel. Moreover, the operated flexible power mode under normal conditions. Meanwhile, they share partial parallel SRDABS....

In this paper, a power module capacitor voltage balancing method is presented for ±350 kV/ 1000 MW modular multilevel converter (MMC) oriented back-to-back grid interconnecting project. method, Balancing Adjusting Number (BAN) proposed to adjust the effect and switching frequency of modules. An accurate calculation also presented. Verification results show effectiveness correctness method.

This article presents a coordinated balancing charging strategy for the cascaded H-bridge inverter (CHBI) with supercapacitor (SC) and dc–dc stage by adopting multistage adjustment of SCs' powers. The power distribution constraints among submodules (SMs) are analyzed to prevent over-modulation H-bridges. reactive is optimized expand stable operation range CHBI in case significant disparity active SMs. relationship powers different SCs also derived under aforementioned constraints. Finally,...