In this manuscript, the optimal location and capacity of Unified Power Flow Controller (UPFC) based on chaotic krill herd (CKH) with runner root algorithm (RRA) for dynamic stability improvement in power system is proposed. The proposed technique is the combined execution of CKH and RRA hence it is known as CKHRA technique. Here, CKH is utilized to optimal location of unified power flow controller when occurring generator fault. CKH chooses maximal power loss line as optimal location to keep UPFC according to the objective function. The minimal voltage deviation is improved using runner root algorithm from the unified power flow controller control parameters. The minimal voltage deviation is utilized to determine the optimal unified power flow controller capacity. The CKHRA technique is executed at MATLAB/Simulink and the performance is assessed by comparison with other techniques. The performance of CKHRA technique is linked with IEEE 14 bus, IEEE 30 bus, IEEE 57 bus bench mark system, whereas the efficiency is examined against various generator fault conditions. By then the statistical analysis, result accuracy percentage and loss sensitivity index are analyzed. The comparative results thus proven the greatness of CKHRA approach and corroborate its ability to improve the dynamic stability of power system.

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Pure and Bi 3+ -doped CePO 4 were synthesized by the simple co-precipitation method. Successful dopant incorporation into the host lattice of orthophosphate without altering the crystalline structure was confirmed by structure analysis, X-ray diffraction, and Raman characterization. Morphological investigation was done using HR-SEM which portrays the co-existence of nanospheres and nanorods in doped CePO 4 and only nanospheres in pure CePO 4 . X-ray photoelectron spectroscopy studies confirm the +3 oxidation state of Ce 3+ and Bi 3+ with the presence of a trace amount of Ce 4+ in the as-prepared nanoparticles. Vibration sample magnetometer studies show weak ferromagnetic behavior of the nanostructures at room temperature. The absorption band in the wavelength range 200−300 nm accounts for 4f−5d electronic transition, and a red shift in the band edge is due to the increase in the band gap with the addition of the dopant. Photoluminescence emission spectra show broad blue-green emission owing to transition of Ce 3+ from the excited state to the ground state and also due to oxygen vacancy. The nonlinear optical absorption and optical limiting (OL) behaviors of Bi 3+ -doped cerium orthophosphate (CePO 4 ) were investigated using an open-aperture (OA) Z-scan technique under an excitation source of 532 nm nanopulsed lasers. The recorded OA transmittance curve reveals a transition from saturable absorption to reverse saturable absorption in pure CePO 4 at 2.46 GW/m 2 , whereas all the doped samples exhibit RSA attributed to 2PA. The increase in the nonlinear absorption (NLA) coefficient with on-axis intensity and the availability of the near resonant energy state due to the Bi 3+ dopant ensure the sequential 2PA (1PA + ESA) phenomenon. Compared to pure CePO 4 , doped nanostructures show improved NLA coefficients due to the availability of the defect state and oxygen vacancies in Bi 3+ -doped CePO 4 . Interestingly, a lower OL threshold (OLT) of 0.14 × 10 −13 W/m 2 is observed in 0.3% Bi 3+ -doped CePO 4 . The lower OLT value of Bi 3+ -doped CePO 4 ensures its potential candidature for OL applications in protecting optical sensors and human eyes.