This study investigates the impact of different flexible AC transmission system (FACTS) devices on critical power quality (PQ) phenomena including voltage sags, harmonics and unbalance from the ...perspective of both mitigation effect and potential negative impact. The FACTS devices, including static VAR compensator, static compensator (STATCOM) and dynamic voltage restorers, are modelled in commercially available software PowerFactory/DIgSILENT to study their impacts on the critical PQ phenomena. Two control strategies, voltage regulation and reactive power compensation, are considered for STATCOM. For DVR, a PI-controller is developed for the purpose of voltage sag mitigation. The merit of the proposed controller is presented by the dynamic response of during fault voltage and the capability of post-fault voltage recovery. The study is carried out on a large-scale generic distribution network. The impact of various devices on PQ phenomena is assessed using appropriate evaluation methodologies, and the results obtained with and without mitigation are presented and compared using heatmaps.
The upcoming network investment decisions and regulatory framework adopted by distribution system operators (DSOs) are most likely to be impacted by the integration of fluctuating distributed ...generation. The economical hosting capacity (HC) improvement method is investigated in this paper as a trade‐off between curtailment and upgrade using a Monte Carlo simulation procedure. The associated costs of both methods are vital indicators for network operators that are trying to maximize the HC and minimize cost. In addition, the breakeven point where curtailment and upgrade costs intersect is the decisive point at which network upgrade becomes sensible as marginal curtailment cost exceeds upgrade cost. A shift in global climate conditions can impact the photovoltaic (PV) levels that motivate network operators to investigate PV penetration, especially in colder climate regions. Thus, the primary objective of this paper is to investigate the shift of the breakeven point to guide DSOs to either adopt PV curtailment as a temporary measure or grid upgrade as a risk aversion strategy considering Finnish climate and load patterns. The real‐time load and PV generation data are utilized for the simulations to consider the dynamic performance indication of three Finnish distribution networks. Curtailment remains a low‐cost option to obtain a percentage HC rise of 13%, 7%, and 8% for rural, suburban, and urban regions, respectively, beyond which curtailment compensation cost surpasses upgrade cost. In essence, PV curtailment serves as an immediate and least‐cost solution to relieve network violations and defer network investment until the HC level (118%, 106%, 97%) making the upgrade a practical option afterwards.
This paper presents an analysis of photovoltaic (PV) hosting capacity improvement through a cost comparison of PV curtailment and network upgrade. This comparative analysis provides economic insights to distribution system operators for taking corrective actions regarding network problems arising due to excessive PV integration.
Traditionally, the economic dispatch problem (EDP) of the bulk generators connected to transmission networks (TNs) is solved in a centralized dispatching center (CDC) while modeling distribution ...networks as passive loads. With the increasing penetration levels of distributed generation, coordinating the economic dispatch between TNs and active distribution networks (ADNs) became vital to maximizing system efficiency. This article proposes a hierarchical communication structure, which requires minimal upgrades to the CDC, for solving the EDP of coupled TNs and ADNs. Based on the minimal data transfer between the CDC and distribution network operators, the problem is formulated and solved while considering the network losses in both TNs and ADNs. Furthermore, a sensitivity analysis is conducted to assess the effect of the R/X ratio of the distribution lines on the economic dispatch solution and the operational cost of the system. The numerical results demonstrate the effectiveness of the proposed centralized scheme and highlight the significance of considering the network losses of both TNs and ADNs when solving the EDP. The results show that the proposed framework can achieve savings of up to 17.98% by taking into account the network losses of TNs and ADNs.
In the energy distribution networks, the most important and valuable equipment is oil-immersed distribution transformers. Besides, due to the key role of these transformers and their multiplicity, ...their lifetime monitoring is inevitable. The life of a transformer depends on the weakest solid insulation material (i.e. paper insulation). On the other hand, monitoring the transformer insulation status requires accurate information to be available about the oil temperature at every moment. Therefore, it is important to control and predict the oil temperature rise in the transformer. In this study, a new model based on fundamental heat transfer theory is proposed for thermal behaviour prediction of top oil of indoor distribution transformers using the concept of thermal resistance, namely electro-thermal resistance model (E-TRM). In E-TRM, the thermal resistance network is formed by following three-dimensional heat transfer path and assigning thermal resistance to each path. To evaluate the proposed E-TRM, the results of this model are verified with experimental results. Moreover, the E-TRM is used to predict the thermal behaviour of the indoor transformer in the overloading condition. At the end, the transformer loss of life is estimated based on the oil temperature and a normal cyclic overloading strategy is presented for overloading management.
Increased penetration of heavy loads is expected to lead to congestion in distribution networks. The distribution network operator can use Demand Side Management (DSM) to motivate consumers to shift ...their load from peak to off-peak times. In this paper, multi-objective optimization is utilized to schedule flexible load to alleviate potential congestions. The proposed scheme minimizes consumers' electricity cost and decreases the peak to average ratio of the load curve to a required level that alleviates existing congestion. This results in a consumer load schedule that is economical and does not require the imposition of congestion tariffs. However, the success of the proposed congestion management scheme relies on the accuracy of the consumer load consumption. Hence, in this paper, uncertainty analysis of consumers' flexible load schedule is executed to ensure the desired robustness of the power flowing in the distribution network to changes in uncertain variables. The results obtained are compared with the existing congestion management scheme demonstrating the advantage of the proposed multi-objective framework in terms of decreasing price and flattening the load curve while alleviating congestion.
All over the world, the operators of the power distribution networks (DNs) are still looking for improving the efficiency of their networks. The performance of DNs and lifetime of its component have ...been significantly affected by its capability of varying their topologies with accurate load gathering via smart grid functions. This paper investigates making use of the smart DNs features and proposes a model of handling the capability of re-allocating the capacitors integrating with configuring the DNs topology. Using the developed formulation, the efficiency of DNs can be improved not only by minimizing the operational costs related to the network losses but also by optimizing the investment costs associated with capacitor re-allocations. Also, various load patterns are employed in the developed formulation to imitate the daily load variations over a year. The improved sunflower optimization algorithm (ISFOA) is proposed in this paper to get the optimal solution of the presented problem. The standard IEEE 33-node feeder and practical 84-node system of Taiwan Power Company (TPC) are the considered test systems. Besides, the uncertainties due to a distributed generation of wind power are investigated via Monte Carlo simulation involved with the proposed ISFOA. Furthermore, to verify the ability of ISFOA to obtain better solutions compared with different recent optimizers, a statistical comparison is carried out based on a large scale 118-node distribution systems. The simulation results reveal that significant technical and economic benefits are obtained by applying the proposed algorithm with higher superiority and effectiveness.
This paper proposes an aerodynamic-constrained frequency response service (FRS) method tailored specifically for active distribution networks (ADNs) which are dominated by distributed wind turbines ...(DWTs). First, a novel equal energy incremental rate criterion (EEIRC) is derived, based on the Karush-Kuhn-Tucker (KKT) condition, for optimally utilizing the rotor kinetic energy that can enhance the frequency regulation capability of DWTs. Next, considering the coupling characteristics of inverter-side frequency and the wind turbine motion, the necessary and sufficient condition is explored for DWTs to maintain mechanical and electrical coupling (MEC) stability as they respond to ADN frequency deviations. Then, leveraging the Lie derivative and Lyapunov theory, the aerodynamic-constrained model adaptive control (ACMAC) is proposed to enable the frequency response of DWT, adapting the frequency control logic autonomously under significant disturbances to prevent DWT instability. Finally, comprehensive simulations are conducted on the modified IEEE 123-bus system with 100% local wind power generation to validate the effectiveness and superiorities of the proposed method.
Water distribution systems are one of the critical infrastructures and major assets of the water utility in a nation. The infrastructure of the distribution systems consists of resources, treatment ...plants, reservoirs, distribution lines, and consumers. A sustainable water distribution network management has to take care of accessibility, quality, quantity, and reliability of water. As water is becoming a depleting resource for the coming decades, the regulation and accounting of water in terms of the above four parameters is a critical task. There have been many efforts towards the establishment of a monitoring and controlling framework, capable of automating various stages of the water distribution processes. The current trending technologies such as Information and Communication Technology (ICT), Internet of Things (IoT), and Artificial Intelligence (AI) have the potential to track this spatially varying network to collect, process, and analyze the water distribution network attributes and events. In this work, we investigate the role and scope of the IoT technologies in different stages of the water distribution systems. Our survey covers the state-of-the-art monitoring and control systems for the water distribution networks, and the status of IoT architectures for water distribution networks. We explore the existing water distribution systems, providing the necessary background information on the current status. This work also presents an IoT Architecture for Intelligent Water Networks - IoTA4IWNet, for real-time monitoring and control of water distribution networks. We believe that, these components need to be designed and implemented effectively to build a robust water distribution network.
Low voltage distribution grids play an important role in the energy transition—both in generation and demand. In the coming decades the reliability of these grids may deteriorate due to asset ageing. ...Various maintenance (replacement) strategies are compared in order to mitigate this. For multiple scenarios, it is analysed under which circumstances and when alternative strategies are more profitable than current practice towards managing low voltage assets. Under all scenarios utilities are advised to actively seek collaboration with other utilities and institutions in order to increase efficiency, reduce nuisance, achieve future‐proofness and minimise risks. Also, opportunities for condition‐based approaches exist with the increasing application of distribution automation.
Reliable water quality monitoring and assessment can help to minimize the risk of water quality failures (WQFs) in water distribution networks (WDNs). Indexing-based water quality assessment ...approaches classify water quality based on contaminant concentrations. However, the resultant indices do not provide any information on trade-offs between water quality and quantity. The need to preserve the earth's natural resources has drawn attention to the use of footprint approaches to assess water quality. This paper uses a water footprint concept to develop a grey water footprint (GWF)-based framework for water quality assessment. A probabilistic human health risk assessment (HHRA) is also incorporated in the GWF approach to address the uncertainties. The proposed framework was implemented by considering the disinfection by-products (DBPs) in WDNs as a case study, and the results were compared with those generated using the Canadian Water Quality Index (CWQI) approach. Six drinking water quality management strategies (DWQMSs) were evaluated. The results from both approaches were correlated, indicating GWF as an alternative to CWQI. The assessment results showed that DWQMSs having groundwater as a source deliver better water quality in terms of DBPs occurrence compared to those using a surface water source. The GWF approach helps categorize water quality by estimating the theoretical volume of fresh water required to dilute the contaminant concentrations to below threshold levels. Water stakeholders can apply this framework considering any contaminants to drinking water quality using a quantitative water footprint scale and develop a trade-off between water quality and quantity management.
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•Water quality assessment was performed using greywater footprint (GWF) approach.•Disinfection by-products (DBPs) data were used to demonstrate the approach.•GWF approach results were validated with indexing approach results.•Water pollution level of DBPs for the given situation was <1%.•GWF for deteriorating drinking water due to DBPs was 6.47 Mm3/year.
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