Distributed generation (DG) systems are integral parts in future distribution networks. In this paper, a novel approach integrating crisscross optimization algorithm and Monte Carlo simulation (CSO-MCS) is implemented to solve the optimal DG allocation (ODGA) problem. The feature of applying CSO to address the ODGA problem lies in three interacting operators, namely horizontal crossover, vertical crossover and competitive operator. The horizontal crossover can search new solutions in a hypercube space with a larger probability while in the periphery of each hypercube with a decreasing probability. The vertical crossover can effectively facilitate those stagnant dimensions of a population to escape from premature convergence. The competitive operator allows the crisscross search to always maintain in a historical best position to quicken the converge rate. It is the combination of the double search strategies and competitive mechanism that enables CSO significant advantage in convergence speed and accuracy. Moreover, to deal with system uncertainties such as the output power of wind turbine and photovoltaic generators, an MCS-based method is adopted to solve the probabilistic power flow. The effectiveness of the CSO-MCS method is validated on the typical 33-bus and 69-bus test system, and results substantiate the suitability of CSO-MCS for multi-objective ODGA problem.
We propose a nested U-shape tube anti-resonant hollow core fiber (UARF) that can effectively reduce the confinement loss (CL) as well as the loss oscillations. The key parameters of UARF have been optimized via numerical analysis. Simulation results show that the CL of proposed UARF is lower than 0.01dB/km over a 550 nm operational bandwidth range from 1.3 µm to 1.85 µm. This CL is nearly one order of magnitude lower than the nested anti-resonant nodeless fiber (NANF). Moreover, the loss ratio between higher-order modes to the fundamental mode is verified to be more than 100,000 over a ultrawide bandwidth of 1000 nm, which indicates its excellent single mode performance. The tolerance towards the structure deformation of UARF has been evaluated for the purpose of practical fiber fabrication. Thus, the proposed UARF has potential application in large capacity data transmission, nonlinear optics, gas sensing and so on.
In this work, we proposed a weakly coupled few-mode hollow-core U-shaped tube nested antiresonant fiber (FM-UARF) for the potential large-capacity mode-division multiplexing transmission without multiple-in-multiple-out (MIMO) digital signal processing. Through theoretical analysis and numerical simulation, the six-tube FM-UARF can be a good candidate for two-mode and three-mode transmission with better performance. After parameter optimization, the weakly coupled condition of effective refractive index difference (Δneff) larger than 5×10−4 can be achieved. Under the two-mode case, the confinement loss (CL) of the LP01 and LP11 modes is less than 0.005 dB/km and 0.1 dB/km in the 700 nm bandwidth range (0.9−1.6µm), respectively. In addition, LP01 achieves the lowest CL of 0.00038 dB/km at a wavelength of 1.06 µm, which gives it potential applications in high-power laser transmission. Under the three-mode case, the CL of the LP01, LP11, and LP21 modes are less than 0.006 dB/km, 0.1 dB/km, and 10 dB/km, respectively, in the wavelength range of 0.95 to 1.65 µm. Both the CL ratios are larger than 150 (23 dB), which ensures the high purity of the supported fiber modes. The results show that the proposed FM-UARF with optimized parameters has the potential in the MIMO-less large-capacity data transmission and so on.
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