Modeling and simulation of new configuration of dynamic voltage restorer for power quality improvement

The dynamic voltage restorer (DVR) is a custom device that is used to maintain the voltage at the load terminals from various power quality problems from a disurbed incoming supply. In this paper, a novel control strategy is described for mitigation of voltage sags and swells on sensitive loads. The new control of the compensation voltages in the DVR based on the dq0 algorithm is discussed. The MATLAB/SIMULINK SimPower System toolbox has been used to obtain simulation results in order to verify the proposed scheme. From the results, it shows that the DVR is able to compensate the voltage sag or swell at sensitive loads by injecting an appropriate voltage through the injection transformer

Double soft-computing techniques based triple functionalities for shunt active power filter with voltage source inverter topology

Firstly, a unified adaptive linear neurons based fundamental component extraction algorithm for dual roles is developed; to generate and synchronize a reference current with respect to the phase and the frequency of supply voltage. A modified method of extracting the final amplitude of the reference current is introduced for improving the quality of the reference current. Second, a hybrid Fuzzy-Proportional (P) controller plus Crisp-Integral (I) controller is designed for a self-charging DC-link voltage control algorithm. The proposed controller is utilized in minimizing the error of DC-link voltage and, its control signal is employed in calculating a reference charging current. The Fuzzy-P controller exhibits simple structure for low computational burden and memory requirement. While, the Crisp-I controller is used to eliminate the steady-state error of DC-link voltage. Performances of the SAPF with the proposed techniques are validated by simulation and experimental works

Muslim consumers’ awareness levels on halal vinegar products: a case study in Selangor

Vinegar is one of the oldest condiments used to this day. The Muslim community considers vinegar a halal product because the Prophet Muhammad (S.A.W) used it as a condiment. However, the ruling of vinegar is not explicitly mentioned in the al-Quran and al-Hadith and even the al-Quran does not specifically mention vinegar, unlike the khamr in which the rule is qaṭ'ī (clear). The absence of these clear guidelines has led to controversy among consumers, where some users were aware of the halal status of vinegar while others are not concerned about it. In this regard, this research aims to study the awareness and concern of Muslim consumers on halal vinegar products in Selangor, Malaysia. A total of 241 users from nine districts in Gombak, Hulu Langat, Hulu Selangor, Klang, Kuala Langat, Kuala Selangor, Petaling, Sabak Bernam and Sepang were selected as respondents using the random sampling method. The information was collected using questionnaire and Google Doc form which was completed by the respondents. The data obtained were analyzed using Statistical Package for Social Sciences (SPSS). The survey found that almost half of the respondents (46.1%) were aware of the existence of various types of vinegar in the Malaysian market. The majority of respondents were very careful in choosing a halal product especially in vinegar product where 90.9% of the respondents only chose halal Muslim vinegar products. However, only 36.1% of the respondents were aware of the product produced through the process of fermentation such as vinegar containing alcohol and therefore only 34.4% found that vinegar also contained alcohol and the level of consumer awareness of the alcohol limit allowed in food and beverages was just 28% of all respondents. However, the majority of respondents were aware that the percentage of alcohol contained in the product will affect the halal status of the product. 53.9% of respondents were aware of the influence while 23.7% were unaware and 22.0% were uncertain. Overall, respondents believe that halal-based vinegar products are guaranteed, so this study implies that the government should enforce the use of halal logos in each product as well as state the alcohol content in the products produced through the fermentation process

Integration of dual intelligent algorithms in shunt active power filter

This paper presents an integration of dual intelligent algorithms: artificial neural network (ANN) based fundamental component extraction algorithm and fuzzy logic based DC-link voltage self-charging algorithm (fuzzy self-charging algorithm), in a three-phase three-wire shunt active power filter (SAPF). The ANN and fuzzy logic are trained using the modified Widrow-Hoff (W-H) weight updating algorithm and fuzzy rules respectively. The controller has utilized both algorithms for producing its reference signals and consequently mitigating distorted source currents, improving system power factor (PF) and regulating the DC-link voltage. A 10kHz pulse-width modulation (PWM) switching algorithm is employed to generate the switching signals and therefore the distorted source currents are reshaped to be sinusoidal source current with low total harmonic distortion (THD) value and in phase with source voltages. The effectiveness of the proposed dual intelligent algorithms is verified using Matlab/Simulink

Significant insights into the operation of DC-link voltage control of a shunt active power filter using different control algorithms: a comparative study

A comparative study between a conventional DC-link voltage control algorithm (CDVCA) and a self-charging DC-link voltage control algorithm (SDVCA) is presented. It focuses on the principle operation of both algorithms and their impacts on the performance of a shunt active power filter (SAPF) operation. All analyses are based on the step response of DC-link voltages under different start-up times of the SAPF and different initial DC-link voltage values. Other considered parameters are the ripple factor (RP) of DC-link voltages, estimated and measured DC-link charging currents, and total harmonic distortion (THD) value of supply currents. Thus, this study provides new insights into the operation of DC-link voltage control using different control algorithms. According to the simulation results, the SAPF using the SDVCA has shown better performance than using the CDVCA. By using the SDVCA, the charging process of a DC-link capacitor starts almost instantaneously. Additionally, the overshoot, settling time, and RF of DC-link voltages are reduced. Other than that, THD values of supply currents are improved, by generating low ripple of estimated DC-link charging currents. Experimental validation of the SAPF using the SDVCA is also presented

Single phase shunt active power filter with simplified ADALINE neural network

Shunt active power filter is known as powerful tool to compensate current harmonics. Previous development of its controller was by using modified ADALINE algorithm for harmonics extraction, which somehow still having complex features. Therefore, this paper presents three major improvements to the algorithm in related to sine and cosine vectors, weight updating algorithm, and average square error. The proposed algorithm is designed and developed in shunt APF's controller, and the shunt APF is simulated in MATLAB/Simulink. The simulation results show significant improvement as compared to the previous algorithm

Self-integrity and family support as assets for resilient urban at-risk youth

While most of the Malaysian youth literature view young people as problematic and chaotic, this research aims to highlight that at-risk young Malaysians also possessed developmental assets which could contribute to their resilience level. This research explores at-risk youth resilience and predicts which protective factor is the most utilized. To be specific, at-risk young people who lived at the outskirt of metropolitan Kuala Lumpur were targeted. Survey designed method on 744 young people of Pantai Dalam, Kuala Lumpur who lived in low cost government flats. Integrity and family support predict levels of resilience. The results show that under disadvantaged environment, family support could sustain young people's resiliency in facing difficulties of life. This research argues that internal asset and family institution contributes to at-risk young people's internal defense system. This research recommends that future research should study the quality of family support and reveal the quality facets of resilience

Prevalens dan tekanan psikologikal dalam kalangan pelajar sekolah menengah yang mencederakan diri tanpa niat membunuh diri di negeri Selangor

Penglibatan golongan remaja dalam tingkah laku mencederakan diri tanpa niat membunuh diri atau Nonsuicidal Self-Injury (NSSI) dilihat semakin kerap dan amat membimbangkan. Tingkah laku ini juga didapati memudaratkan diri sendiri baik dari segi fizikal dan mental. Selain daripada faktor sosial dan persekitaran, faktor dalaman seseorang individu seperti tekanan psikologikal turut menyumbang kepada tingkah laku NSSI. Kajian ini dijalankan untuk membentangkan prevalens NSSI dalam kalangan pelajar sekolah menengah di negeri Selangor serta mengenal pasti perbezaan tahap tekanan psikologikal yang dialami antara pelajar yang pernah dan tidak pernah terlibat dalam NSSI. Kajian ini dilakukan melalui kaedah kuantitatif iaitu metod survei dengan menggunakan borang soal selidik yang merangkumi item berkaitan NSSI dan juga instrumen General Health Questionnaire (GHQ-12). Responden kajian ini melibatkan 1021 pelajar sekolah menengah yang dipilih menggunakan kaedah persampelan rawak. Secara keseluruhannya, kadar prevalens NSSI dalam kalangan pelajar sekolah menengah di Selangor ialah 15.1% di mana prevalens dalam kalangan pelajar lelaki ialah 14.2% dan pelajar perempuan ialah 16.1%. Hasil analisis Ujian T Sampel Bebas menunjukkan terdapat perbezaan signifikan bagi tahap tekanan psikologikal (t(1019)=8.28, p<.001 yang dialami antara pelajar yang pernah mencederakan diri dan tidak pernah mencederakan diri. Pemahaman yang mendalam tentang faktor psikologikal terhadap tingkah laku NSSI dapat memberi pendedahan kepada pelbagai pihak termasuklah badan kaunseling dan kesihatan mental bagi mengenal pasti langkah pencegahan proaktif serta intervensi yang boleh diambil untuk membanteras tingkah laku mencederakan diri

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake