Flexible Compensation of Voltage and Current Unbalance and Harmonics in Microgrids

In recent years, the harmonics and unbalance problems endanger the voltage and current quality of power systems, due to increasing usage of nonlinear and unbalanced loads. Use of Distributed Generation (DG)-interfacing inverters is proposed for voltage or current compensation. In this paper, a flexible control method is proposed to compensate voltage and current unbalance and harmonics using the distributed generation (DG)-interfacing inverters. This method is applicable to both grid-connected and islanded Microgrids (MGs). In the proposed method, not only the proper control of active and reactive powers can be achieved, but also there is flexibility in compensating the voltage or current quality problems at DG terminals or Points of Common Coupling (PCCs). This control strategy consists of active and reactive power controllers and a voltage/current quality-improvement block. The controller is designed in a stationary (αβ) frame. An extensive simulation study has been performed and the results demonstrate the effectiveness of the proposed control scheme. Depending on the compensation modes, the harmonics and unbalance compensation of DG output current, MG-injected current to the grid, as well as PCC and DG voltages, can be achieved in grid-connected operation of MG while in the islanded operation, and the PCC and DG voltages compensation can be obtained through the proposed control scheme

Evaluation of health-related quality of life after total hip arthroplasty: A case-control study in the Iranian population

Background: As the total hip arthroplasty (THA) mainly aims to improve the quality of life of the patients, study of health-related quality of life (HRQoL) after THA has attracted much attention. Yet, the results considerably vary between studies. Here, we evaluate the HRQoL of the patient after THA, for the first time in the Iranian population. Methods: In a case-control study, HRQoL was assessed in 217 patients after THA and compared with a matched reference population. The 36-item short-form health survey (SF-36) was used for the evaluation of HRQoL. A multiple linear regression model was used to investigate the influence of sociodemographic and clinical characteristics of the patients on the HRQOL. Results: The mean follow-up of the patients was 27 ± 18 months. The mean total SF-36 score was 41.4 ± 22.2 in the case and 67.3 ± 26.6 in the control group (p = 0.001). The mean physical component score, but not the mental component score, was significantly lower in the patient group (p = 0.001). Except for the vitality and emotional role, all other SF-36 subscales were significantly lower in the case group. Male sex (B = 4.52, p = 0.023), number of comorbidities (B = - 4.82, p = 0.011), body mass index (B = - 1.18, p = 0.044), number of post-operative complications (B = - 6.57, p = 0.001), and adherence to physiotherapy protocol (B = 2.09, p = 0.014) were associated with HRQoL after THA. Conclusion: Although THA is considered as one of the most successful orthopedic practices, it is associated with remarkable reduced HRQoL in Iranian population when compared with the reference population. A variety of patients-associated factors influence the HRQoL after THA. © 2019 The Author(s)

Impact of independent and non-independent parameters on various elements’ rejection by nanofiltration employed in groundwater treatment

Nanofiltration is one of the widely used robust methods in water sweetening throughout the world. This work highlights the comparison of the impact of independent and non-independent parameters on element rejection to treat groundwater of a region located in Qazvin province, Iran. A pilot-scale FILMTEC-NF90-4040 nanofilter membrane was applied. Samples were collected from three various wells and the volume of 50 cc was tested, each of which was tested three times, and then cations and anions were measured in raw water and treated water by ion chromatography. The data collection and operation of the system was performed by the 761 compact IC version 1.1 software where statistical analyses were performed with SPSS, version 19. Results showed that the degradation efficiency of divalent ions was greater than that of monovalent cations. The content of ion rejection in the nanofilter membrane was not an independent phenomenon. For instance, the results revealed that the presence of high magnesium ion is very effective in disposing sodium ion. At the same time, the rejection rate of ions does not always follow the Van’t Hoff series. Optimal pressure was determined to be 10 bar

An intelligent energy management strategy for an off-road plug-in hybrid electric tractor based on farm operation recognition

Abstract Due to the growing emergence of vehicle electrification, agricultural tractor developers are launching hybrid powertrains in which energy management strategy (EMS) assumes a prominent role. This work mainly aims at developing an EMS for a plug-in hybrid electric tractor (PHET) to minimise fuel consumption and increase the operating range. The developed off-road PHET power sources are composed of a biogas-fuelled Internal Combustion Engine Generator (Bio-Gen), a photovoltaic system, and a battery pack. To control the power flow among different sources, a two-layer EMS is formulated. In this regard, initially, the farm operating mode is recognised by means of classification of a working cycle's features. Then, a control strategy based on a multi-mode fuzzy logic controller (MFLC) is employed to manage the power flow. At each sequence, the classifier identifies the farm operation condition and accordingly activates the relative mode of the MFLC to meet the requested power from the Bio-Gen. The performance of the proposed EMS has been evaluated based on three real-world typical agricultural working cycles. The results demonstrate the successful performance of the proposed intelligent EMS under farm conditions by maintaining the energy sources' operation in a high-efficiency zone which can lead to the extension of the working range and decrease fuel consumption

The efficacious of AOP-based processes in concert with electrocoagulation in abatement of CECs from water/wastewater

Combining electrocoagulation with another process is a potential strategy for increasing the efficiency of water and wastewater pollutant removal. The integration of advanced oxidation processes (AOPs) and electrocoagulation (EC) demonstrates improved performance. The mechanism of the EC combined with ozone (O3), hydrogen peroxide (H2O2), sulfate radicals, electrooxidation (EO), Fenton/electro-Fenton, and UV is discussed. This review sheds light on EC-AOP hybrid processes in terms of their mechanisms, development, challenges, and their potential application for the removal of contaminants of emerging concern (CECs). The majority of the articles claimed improved performance of the EC process when combined with AOP as a pre-treatment, especially in terms of removing recalcitrant contaminants. For instance, the integrated EC-Fenton/photo-Fenton processes have been shown to be a promising treatment to virtually complete removal of the phenolic compounds in oil refinery wastewater. In EC-EO process, boron doped diamond (BDD) anode, despite being costly electrode, has the highest oxidation potential and is therefore the most suitable type for the mineralization of organic pollutants. PFASs are more effective at being removed from water through zinc and Ti4O7 electrodes in EC-EO treatment. Furthermore, the peroxone and synergistic effects between O3 and coagulants played almost equal dominant role to removal of ibuprofen using hybrid EC-O3. However, enough data for conducting these integrated processes at industrial scale or with real wastewaters do not exist, and so there is a lack for comprehensive and systematic approaches to address complexity of such systems. Although a great number of papers were focused on the degradation of effluents from different industries, viruses, and pharmaceuticals, there is not sufficient research in terms of the removal of herbicides, pesticides, microplastics, and micropollutants