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Improved Stability and Damping Characteristics of LCL-Filter Based Distributed Generation System
Faiz Muhammad Talib,Khan Danish,Khan Muhammad Mansoor,Ali Abdar,Tang Houjun 대한전기학회 2021 Journal of Electrical Engineering & Technology Vol.16 No.3
The voltage source inverter is a key component in the distributed power generation systems where the LCL -fi lter is a popular choice for interfacing with the grid. However, the well-known resonance issue associated with the LCL -fi lter deteriorates the control performance and risk the inverter system stability. The inverter control design plays a signifi cant role to ensure the quality of the injected grid current and stable operation according to the requirements of grid interconnection standards. This paper deals with an alternative control design method that modifi es the internal damping loop design to improve the stability and damping characteristics. The proposed design employs a compensator across the fi lter and feedbacks the output of the augmented plant at the reference voltage point, and named as parallel feedforward compensation method. The fi lter capacitor current measured for damping loop implementation, and a high-pass fi lter compensator adopted in the proposed confi guration. The proportional capacitor current feedback compensation method is considered for comparative studies. The current loop stability and control performance characteristics are investigated in detail under the resonance frequency and fi lter parameters variation condition. The signifi cant outcomes of the proposed scheme are faster dynamic response, higher delay compensation capability, relatively improved resonance suppression, and potential for better tracking performance. An experimental prototype is developed to validate the effi cacy of the proposed method.
Muhammad Usman Rashid,Faiz Ali Khan,Noor Muhammad,Asif Loya,Ute Hamann 대한암학회 2019 Cancer Research and Treatment Vol.51 No.3
Purpose Partner and localizer of BRCA2 (PALB2) is a breast cancer susceptibility gene that plays an important role in DNA repair. This is the first study assessing the prevalence of PALB2 mutations in early-onset and familial breast/ovarian cancer patients from Pakistan. Materials and Methods PALB2 mutation screening was performed in 370 Pakistani patients with early-onset and familial breast/ovarian cancer, who were negative for BRCA1, BRCA2, TP53, CHEK2, and RAD51C mutations, using denaturing high-performance liquid chromatography analysis. Mutations were confirmed by DNA sequencing. Novel PALB2 alterations were analyzed for their potential effect on protein function or splicing using various in silico prediction tools. Three-hundred and seventy-two healthy controls were screened for the presence of the identified (potentially) functional mutations. Results A novel nonsense mutation, p.Y743*, was identified in one familial breast cancer patient (1/127, 0.8%). Besides, four in silico-predicted potentially functional mutations including three missense mutations and one 5' untranslated region mutation were identified: p.D498Y, novel p.G644R, novel p.E744K, and novel c.-134_-133delTCinsGGGT. The mutations p.Y743* and p.D498Y were identified in two familial patients diagnosed with unilateral or synchronous bilateral breast cancer at the ages of 29 and 39, respectively. The other mutations were identified in an early-onset (! 30 years of age) breast cancer patient each. All five mutations were absent in 372 healthy controls suggesting that they are disease associated. Conclusion Our findings show that PALB2 mutations account for a small proportion of early-onset and hereditary breast/ovarian cancer cases in Pakistan.