Orthogonal frequency division multiplexing (OFDM) is a popular method for high data rate wireless transmission.OFDM may be combined with antenna arrays at the transmitter and receiver to increase diversity gain and/or enhance system capacity on time-variant frequency-selective channels, resulting in multiple-input multiple-output (MIMO) configuration.This paper explores various physical layer research challenges MIMO-OFDM design, including channel measurements modelling, analog beam forming...

Orthogonal frequency-division multiplexing (OFDM) is one of the promising techniques for future mobile wireless data systems. For OFDM systems with cochannel interference, adaptive antenna arrays can be used interference suppression. This paper focuses on a key issue arrays, that is, parameter estimation minimum mean square error (MMSE) diversity combiner (DC). Using instantaneous correlation approach developed in paper, an original estimator MMSE-DC derived. Based estimator, we propose...

A novel force-commutated three-level boost-type rectifier is proposed. The draws nearly sinusoidal current from the utility with unity fundamental power factor. High reliability possible due to its shoot-through free structure. Doubled DC bus voltage compared a normal single-level also because of neutral point clamping. operating principle, steady state analysis, input and control schemes, detailed experimental results are presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML"...

This paper explores the use of GaN power FETs to realize an integrated modular motor drive (IMMD) with induction motor. A structure in which inverter modules are connected series is proposed reduce module maximum voltages and offer opportunity utilize low-voltage wide-band-gap devices. With superb switching performance FETs, a reduction IMMD size achieved by eliminating heat sink optimizing dc-link capacitors. Gate signals interleaved suppress total voltage ripple capacitors further...

DC fault current limitation is important for the low-voltage dc distribution network, because existing selective protection cannot act fast enough. However, typical limiting method-installing reactors directly in system-will lead to negative influence on system normal operation and circuit breaker (DCCB) isolation. This paper proposed a novel solid-state (SSCB) with self-adapt capability, namely, no network operation, swift response fault, efficient cooperation between The hybrid...

The fast dc line protection is one of the key techniques for multi-terminal flexible grid whose main technical difficulty lies in quick and reliable fault identification. traditional principles ac system are not suitable grid, those conventional transmission can also be applied directly. Therefore, frequency-domain traveling-wave boundary characteristics after faults analyzed first this paper to find critical condition distinguishing internal external as well forward backward faults. And...

In the production of isopropyl alcohol, diisopropyl ether appears as a byproduct. Diisopropyl and alcohol form binary minimum-boiling homogeneous azeotrope. this paper, two methods are explored to achieve separation azeotrope: fully heat-integrated pressure-swing distillation extractive with 2-methoxyethanol an entrainer. The optimal design dynamic control processes investigated, respectively. It is revealed that system offers 5.75% reduction in total annual cost 7.97% saving energy...

The overhead line will be widely applied in the future flexible high-voltage dc (HVDC) grid. Correspondingly, effective reclosing strategy which can identify fault property must configured for circuit breaker (DCCB) to improve system power supply reliability. However, if DCCB is reclosed directly, large second overcurrent may occur damage vulnerable devices system. Therefore, inherent voltage characteristic difference between different faults (nonpermanent or permanent) analyzed paper. And...

This paper presents an online smart meter measurement error estimation algorithm. Extended Kalman filter (EKF) and limit memory recursive least square (LMRLS) methods are used for remote calibration of a large amount user-side meters. Then, modified joint model is obtained by selecting the step that conforms to actual working condition filtering abnormal value according line loss rate characteristics. Finally, based on experimental data program-controlled load simulation system, precision...

Fast and reliable direction criterion is important for the protection of multi-terminal HVDC grid, not only pilot protection, but also excluding backward fault in singleended protection. The criteria based on dc current variation (Δi) or change rate (di/dt) have been used transmission system. However, acting reliability influenced by high-transition resistance, line distributed capacitance, so on. Although boundary effect reactor excellent operation performance they are feasibility when...

We analyze the impact of a time-varying Rayleighfading channel on performance an Alamouti transmit-diversity scheme.We propose several optimal and suboptimal detection strategies for mitigating effects channel, derive expressions their bit-error probability as function correlation coefficient .We find that maximum-likelihood detector optimally compensates timevarying is very tolerant to fading, attaining full diversity order even extreme case = 0.In contrast, although lower in complexity,...

Medium voltage direct current (MVdc) distribution system has numerous advantages over medium alternative system. However, two shortcomings of the existing hybrid circuit breaker (DCCB) with load switch, including high construction cost and operating losses, have constrained application DCCBs in MVdc To overcome these shortcomings, a novel multi-port DCCB negative source (NVS) been proposed this paper. First, general topology working principle NVS are presented. Then, focused on commutation...

In the flexible dc grid, fault propagates extremely fast. It requires protection and circuit breaker (DCCB) can identify isolate line very quickly, for healthy network ride-through, especially in multi-terminal grids. However, existing DCCB techniques grid still not match propagation speed. Therefore, a novel current-commutation-based current limiter (FCL) is proposed this paper. limit effectively, to guarantee converter continuous operation ride-through after faults, so requirement on...

In the multi-terminal flexible dc grid, it is important for healthy network to ride through fault. The converters should operate continuously after faults, staying unblocked. But existing selective protection and isolation method may fail react swiftly enough, because propagation speed of fault current extremely fast. This paper discussed limiting requirements proposed a calculation determine required reactor value, purpose converter continuous operation during faults. On this basis,...

Renewable energy integrated with hydrogen storage for power generation is a promising alternative achieving cleaner source transition. However, the volatility and intermittency of renewable pose significant challenges to safe efficient operation proton exchange membrane fuel cells (PEMFC) system. Due complex thermal-water-electrical fields coupling mechanism, quantitative analysis dynamic performance PEMFC under changes in system operating conditions at multiple time scales has not been...

In this paper, pressure-swing distillation (PSD) is applied to separate pressure-insensitive minimum boiling azeotrope methanol/toluene via introducing chloroform as a light entrainer. The feasibility of process verified by analyzing the residue curve maps. Both partially and fully heat-integrated PSD processes are implemented. steady-state designs these optimized based on total annual cost (TAC). extended process, high-pressure column (HPC) serves homogeneous azeotropic column, while...

DC circuit breaker (DCCB) is one of the most important technologies for safe and reliable operation dc grid. And hybrid DCCB (HCB) obviously promising in high-voltage application area, because it combines both advantages mechanical solid-state DCCB. At present, insulated gate bipolar transistors (IGBTs) are generally used configuring main branch HCB. Compared with IGBTs, thyristors have merits ability to bear higher surge current, reliability, lower cost, thus being more economical when...