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Over the last few years, the number of grid-connected photovoltaic systems (GCPVS) has expanded substantially. The increase in GCPVS integration may lead to operational issues for the grid. Thus, modern GCPVS control mechanisms should be used to improve grid efficiency, reliability, and stability. In terms of frequency stability, conventional generating units usually have a governor control that regulates the primary load frequency in cases of imbalance situations. This control should be activated immediately to avoid a significant frequency variation. Recently, renewable distribution generators such as PV power plants (PVPPs) are steadily replacing conventional generators. However, these generators do not contribute to system inertia or frequency stability. This paper proposes a control strategy for a GCPVS with active power control (APC) to support the grid and frequency stability. The APC enables the PVPP to withstand grid disturbances and maintain frequency within a normal range. As a result, PVPP is forced to behave similar to traditional power plants to achieve frequency steadiness stability. Frequency stability can be achieved by reducing the active power output fed into the grid as the frequency increases. Additionally, to maintain power balance on both sides of the inverter, the PV system will produce the maximum amount of active power achievable based on the frequency deviation and the grid inverter’s rating by working in two modes: normal and APC (disturbance). In this study, a large-scale PVPP linked to the utility grid at the MV level was modeled in MATLAB/Simulink with a nominal rated peak output of 2000 kW. Analyses of the suggested PVPP’s dynamic response under various frequency disturbances were performed. In this context, the developed control reduced active power by 4%, 24%, and 44% when the frequency climbed to 50.3 Hz, 50.8 Hz, and 51.3 Hz, respectively, and so stabilized the frequency in the normal range, according to grid-code requirements. However, if the frequency exceeds 51.5 Hz or falls below 47.5 Hz, the PVPP disconnects from the grid for safety reasons. Additionally, the APC forced the PVPP to feed the grid with its full capacity generated (2000 kW) at normal frequency. In sum, the large-scale PVPP is connected to the electrical grid provided with APC capability has been built. The system’s capability to safely ride through frequency deviations during grid disturbances and resume initial conditions was achieved and improved. The simulation results show that the given APC is effective, dependable, and suitable for deployment in GCPVS.

The level of potentially toxic elements (PTE) in phytopharmaceuticals can be a potential threat to human health through the food chain. The traditional herbal medicinal products (THMPs) with the marshmallow root (Althaea officinalis L., radix), which we can find in European pharmacies, are widely used among the European population. However, recently, voices have been heard in the public about alleged PTE occurrence. In this article, the levels of Pb and Cd impurities were measured in samples of THMPs with marshmallow root available in Polish pharmacies (n = 10). Our proposed toxicological approach was based on two important issues. The first was PTE levels (Pb: 1.60–6.80 μg/L and Cd: 0.80–3.81 μg/L presented as raw results) in comparison with the permissible limit set by FAO/WHO for medicinal herbs (10,000 µg/kg for Pb and 300 µg/kg for Cd) and also ICH Q3D guidelines (0.5 μg/g for Pb and also Cd). The second was the estimation of exposure of investigated PTE in a single dose and daily dose for each THMP. It should be noted that the content of analyzed heavy metals in a single dose of analyzed products was very low, and hence is not a threat for patients. The obtained daily intake of heavy metals impurities in comparison with PDE values confirms the safety of all analyzed phytopharmaceuticals (all of the samples meet the standards of the ICH Q3D guideline). It can be summarized that each of the analyzed THMP with marshmallow root available in Poland are safe for the patients. Based on literature review, this article is the first study about heavy metals impurities level in final THMPs with A. officinalis L., radix (marshmallow root) available in European pharmacies.

In this paper, emerging 5G mobile services are investigated and categorized from the perspective of not service providers, but end-users. The development of 5G mobile services is based on an intensive analysis of the global trends in mobile services. Additionally, several indispensable service requirements, essential for realizing service scenarios presented, are described. To illustrate the changes in societies and in daily life in the 5G era, five megatrends, including the explosion of mobile data traffic, the rapid increase in connected devices, everything on the cloud, hyper-realistic media for convergence services and knowledge as a service enabled by big-data analysis, are examined. Based on such trends, we classify the new 5G services into five categories in terms of the end-users’ experience as follows: immersive 5G services, intelligent 5G services, omnipresent 5G services, autonomous 5G services and public 5G services. Moreover, several 5G service scenarios in each service category are presented, and essential technical requirements for realizing the aforementioned 5G services are suggested, along with a competitiveness analysis on 5G services/devices/network industries and the current condition of 5G technologies.

The generation and integration of photovoltaic power plants (PVPPs) into the utility grid have increased dramatically over the past two decades. In this sense, and to ensure a high quality of the PVPPs generated power as well as a contribution on the power system security and stability, some of the new power quality requirements imposed by different grid codes and standards in order to regulate the installation of PVPPs and ensure the grid stability. This study aims to investigate the recent integration requirements including voltage sag, voltage flicker, harmonics, voltage unbalance, and frequency variation. Additionally, compliance controls and methods to fulfill these requirements are developed. In line with this, a large-scale three-phase grid-connected PVPP is designed. A modified inverter controller without the use of any extra device is designed to mitigate the sage incidence and achieve the low-voltage ride-through requirement. It can efficiently operate at normal conditions and once sag or faults are detected, it can change the mode of operation and inject a reactive current based on the sag depth. A dynamic voltage regulator and its controller are also designed to control the voltage flicker, fluctuation, and unbalance at the point of common coupling between the PVPP and the grid. The voltage and current harmonics are reduced below the specified limits using proper design and a RLC filter. The obtained results show that the proposed controller fulfilled the recent standard requirements in mitigating power quality (PQ) events. Thus, this study can increase the effort towards the development of smooth PVPP integration by optimizing the design, operation and control strategies towards high PQ and green electricity.

Requirements Technical Debt (RTD) applies the Technical Debt (TD) metaphor to capture the consequences of sub-optimal decisions made concerning Requirements. Understanding the quantification of RTD is key to its management. To facilitate this understanding, we developed a conceptual model, the Requirements Technical Debt Quantification Model (RTDQM). Our work is grounded in the literature found via a systematic mapping study and informed by prior work modeling the quantification of software code-related TD types. The key finding is that although RTD is similar to code-related TD in many aspects, it also has its own components. RTD can be incurred regardless of the presence of code-related TD. Unlike code-related TD, RTD has a feedback loop involving the user. RTD can have a cascading impact on other development activities, such as design and implementation, apart from the extra costs and efforts incurred during requirements engineering activities; this is modeled by the RTD Interest constituents in our model. The model was used to compare and analyze existing quantification approaches. It helped identify what RTD quantification concepts are discussed in the existing approaches and what concepts are supported by metrics for their quantification. The model serves as a reference for practitioners to select existing or to develop new quantification approaches to support informed decision-making for RTD management.

At present, the energy transition is leading to the replacement of large thermal power plants by distributed renewable generation and the introduction of different assets. Consequently, a massive deployment of power electronics is expected. A particular case will be the devices destined for urban environments and smart grids. Indeed, such applications have some features that make wide bandgap (WBG) materials particularly relevant. This paper analyzes the most important features expected by future smart applications from which the characteristics that their power semiconductors must perform can be deduced. Following, not only the characteristics and theoretical limits of wide bandgap materials already available on the market (SiC and GaN) have been analyzed, but also those currently being researched as promising future alternatives (Ga2O3, AlN, etc.). Finally, wide bandgap materials are compared under the needs determined by the smart applications, determining the best suited to them. We conclude that, although SiC and GaN are currently the only WBG materials available on the semiconductor portfolio, they may be displaced by others such as Ga2O3 in the near future.

Today, the pace of development of decentralized transactive management systems has increased significantly due to growing renewable energy source technologies and communication infrastructure at the distribution system level. Such bilateral energy transactions have changed the structure of electricity markets and led to the emergence of a local energy market in electricity distribution. While examining this change of attitude, this paper analyzes the effects of local market formation on the performance and performance of distribution companies. Accordingly, the technical requirements in the three areas of operation, network control, and ICT in the new workspace are thoroughly examined. The hardware requirements will be presented in two parts for the end-user and the distribution systems. Then, the proposed local distribution market framework will be introduced, and finally, the conclusion will be presented.

PurposeLean management is a suitable methodology for companies that want to improve their productive performance and competitiveness. This study aims to research levels of implementation and internalisation of Lean production tools in Spanish manufacturing companies, and explores differences in behaviour between SMEs and large companies based on data gathered over three time periods. The correlation between Lean adoption and company performance is also analysed.Design/methodology/approachCompany survey data for the years 2012, 2015 and 2018 collected from 354 respondents were used to conduct a longitudinal study on the level of lean tool adoption and internalisation in manufacturing companies.FindingsOver the years, the use of Lean tools has increased, whereas levels of internalisation have remained stable. Lean tool use in SMEs and large companies show significant differences in 2012 and 2015, but this is no longer the case 2018. Results also show that higher Lean tool use helps increase return on sales (ROS), and higher levels of internalisation of tools helps reduce the number of products rejected.Originality/valueTo date, there are no known studies on the use and internalisation of Lean tools or their correlations with business performance indicators in Spanish manufacturing companies.

This paper presents an extended investigation into the role of environmental assumptions in the emergence and management of Requirements Technical Debt (RTD). Building on earlier work that identified environmental assumptions as a critical yet often overlooked source of RTD, we provide a comparative evaluation of seven representative modeling frameworks: KAOS, i*, Obstacle Analysis, Failure Frames, Claims, SysML, and RDAL. The analysis is structured around five dimensions: modeling focus, tracing support, validation capability, integration readiness, and assumption evolution. The results show substantial variation in support for assumption management. Among the frameworks, KAOS and Obstacle Analysis stand out for explicitly modeling assumptions and their violations. SysML, on the other hand, is particularly strong in its ability to integrate with industrial toolchains. RDAL demonstrates its greatest strength in tracing, where assumptions, requirements, and verification conditions are systematically linked, though its explicit modeling support remains more limited compared to goal-oriented approaches. i* and Claims capture assumptions more implicitly, with weaker validation and evolution capabilities, while Failure Frames focus on assumption violations but lack integration with broader MBSE workflows. The paper’s main contribution is a synthesis of trade-offs across assumption-aware modeling frameworks, highlighting both their strengths and remaining gaps. This provides actionable insights for researchers and practitioners in selecting, combining, or extending modeling approaches to better manage environmental assumptions and mitigate assumption-related technical debt.

Environmental assumptions, which are expectations about a system’s operating context, play a critical yet often underexplored role in the emergence of requirements technical debt (RTD). When these assumptions are incorrect, incomplete, or evolve over time, they can compromise the validity of system requirements and lead to costly rework in later stages of development. This paper investigates how environmental assumptions influence the identification of RTD through the analysis of a real-world case study in the domain of small uncrewed aerial systems (sUASs). A structured qualitative analysis of safety-related requirements and their associated assumptions was conducted to examine how deviations in these assumptions can introduce various forms of RTD. This work addresses a gap in the literature by explicitly focusing on the role of environmental assumptions in RTD identification. A classification framework is proposed, highlighting five distinct types of assumption-driven RTD. This framework serves as a foundation for supporting early detection of debt and improving the sustainability and resilience of software-intensive systems.