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Due to environmental and energy policies in recent years, some countries will install many PV generations into power systems in the future. Under this condition, it is worrisome that the disconnection of the PV occurs because of a voltage drop triggered via a system fault, which impacts the stability of the PV(photovoltaic).A technique of FRT (Fault Ride Through) is an expected solution for PVs. However, just the FRT requirements for PVs do not inevitably increase the stability of the power system. Solving the problem of the instability of the inverter control in a grid-connected PV needs reasonable consideration. This paper proposed an automatically independent controlling algorithm of the PV inverter considering dynamic load features and Active LVRT (low voltage ride through) capability to increase the robustness and performance of the grid-connected PV system, and both simulation and experimental results showed that the condition of a range from an IM rate = 20[%] to an IM rate=40[%] could best meet the requirements for the PV outputting recovery and the average tracking error of the input current reduced by nearly 10%. Also, the average output current tracking error was reduced by about 4%. This shows that the tracking performance has significantly improved.

An MPPT (Maximum Power Point Tracking) plays a vital role in a photovoltaic(PV) power generation system. Applying the optimum MPPT is a significant way to achieve an efficient PV system. The MPPT methods’ efficiency counts on the two MPPT factors, including the perturbation period and the perturbation amplitude. Nevertheless, realizing MPPT in the photovoltaic array is very hard when the natural conditions change, especially for the temperature and light intensity. This paper proposed a new method based on Conjugate Gradient (CG) to address the problem of hard reasonable considering both dynamic and steady-state performance in some existing MPPT algorithms. Meanwhile, the presented algorithm can effectively adjust the output of PV cells by controlling the boost DC/DC converter. Finally, the experimental and simulation results show the system can quickly get the maximum power point and have performance.

The dynamic motion of a span is coupled to the other spans in transmission lines. From the continuity conditions, force equilibrium conditions, and dynamical equations of every span conductor and insulator string, a close-form expression for the dynamic stiffness of a coupled two spans in harmonic motion is presented. Unlike some existing theories of single span conductor, the effect between the conductors and insulator strings is considered here. By means of example calculations, the validity of the dynamic stiffness of two-span is demonstrated by the consistency of the results determined by the ABAQUS. Meanwhile, the dynamic stiffness and natural frequency are discussed under variation of the span lengths ratio, Irvine parameter, and insulator string length. Moreover, the modal shape function corresponding natural frequency is derived, and the contribution of localization mode is studied. The results show that the contribution is either sensitive to or independent of transmission line parameters in certain parameter ranges. Finally, generalizing the work of two-span, the dynamic stiffness of arbitrary span number is obtained.

Frequency Hopping (FH) is a significant anti-interception and anti-interference, so some wireless communication systems extensively use it. Then it can offer better security performance of the system via combining cryptographic algorithms with FH. This paper presents a detailed theoretical design and hardware implementation of an evolutionary ZUC stream cipher algorithm on FPGA. Using some encryption algorithms can improve the security of the FH system by increasing its complexity, including SNOW3g, ZUC algorithm, Chaos system, and other cipher methods. ZUC (named for Zu Chongzhi, a famous mathematician in ancient China) is bitstream encryption that builds the core of the 3GPP integrity algorithm 128-EIA3 and the 3GPP confidentiality algorithm 128-EEA3, providing authentic security services in 4G, even in 5G (IMT-2020) to some extent. The article presented an evolutionary three-layers structure of the ZUC FH system, which innovatively applied the permutation polynomial algorithm and an evolutionary DES cipher algorithm. The introduction of that new DES and the permutation polynomial can efficiently increase the security performance of the ZUC system but also avoid some shortcomings of the UHF (Ultra High Frequency) communication. The experiment of this research designed software by coding VHDL language and implemented hardware using a XILINX Virtex-5 FPGA. The finished experiment gave, analyzed, and compared all results according to the performance of the proposed system and hardware resources. The tests for evaluating the randomness and security denote that the constructed sequences have better performance, including the randomness, linear complexity, and hamming correlations, and pass the NIST test finally. The experimental results show that this improved ZUC cipher stream algorithm proposed in the article can provide a high throughput of 2.08 Gbps under a 65MHz clock frequency. The authors will focus their future work on applying the evolutionary S-box and the algorithm with better security performance.

The 3-D TLC NAND flash memory significantly increases the storage capacity but makes data more prone to errors. To address the reliability problem, Polar Code is one coding method that can reach the channel capacity (Arikan 2009). However, the 3-D NAND flash memory channel is uncertain due to the variation of retention time and program/erase(P/E) cycle. So it is difficult to construct a Polar Code in the NAND flash memory. This letter proposes a new Polar Code construction method called dynamic merge Monte Carlo (DMMC). DMMC uses the Monte Carlo method to obtain the optimal Polar Code construction and then reduces the space overhead by combining similar construction so that it can be used in flash memory systems. Compared with the conventional method, the uncorrectable bit error rate (UBER) of the proposed method can reduce by up to 90.5%, and the read latency can reduce by more than 50%. [ABSTRACT FROM AUTHOR]