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The energy transition is aimed to take advantage of the operational flexibility of hydropower to extend the integration of intermittent renewable sources. Consequently, the hydrogenerators will have to operate in regimes far away from their designed best-point operation. In order to accurately assess the impact, this paper presents a useful approach to determine the overall operating efficiency of synchronous generators under intermittent operation. An accumulated average efficiency (AAE) model is proposed and compared against an alternative approach; the weighted average efficiency (WAE) model. It is found that the WAE approach produces unrealistic low efficiencies when the generator operates in synchronous condenser mode (SCM) for long periods. In general, the AAE supersedes the WAE for all the different load distributions that were investigated. This was further illustrated by a worked example and by constructing more complex load distributions. A load distribution dominated by SCM yields a difference as high as $33.18 \,\%$ , while an even distribution deviates $1.43 \,\%$ in their respective efficiencies. Finally, a yearly on-site measurement of our studied $103 \,\mathrm{MVA}$ generator’s concentrated load distribution revealed a discrepancy of $0.67 \,\%$ , which is a significant deviation considering what the operating regime would mean in terms of economic implications. [ABSTRACT FROM AUTHOR]

Achieving the low-carbon transition of power systems requires the coordination of renewable energy generation and other emerging electricity technologies. Their technical indicators are changing rapidly since these technologies are in the initial stages of development. Determining the technical and policy targets for achieving the low-carbon transition is critical for regulators and power system planners. This paper defines this problem as a backcasting problem, whose concept is derived from environmental science research. We introduce it into the power system planning field and innovatively model it as a bi-level optimization problem. According to the characteristics of the backcasting problem, an improved barrier method is proposed to solve it efficiently. The effectiveness of the proposed model and algorithm are verified through case studies on a modified Garver’s 6-bus system and a realistic Northwest China power system, and they are compared with state-of-the-art solution techniques. The results of the backcasting problem provide a new perspective on the economic impacts of the low-carbon transition and are helpful in energy policy formulation for power systems. [ABSTRACT FROM AUTHOR]

In this paper, the closed-loop supply chain (CLSC) models are extended to consider the case that the manufacturer can improve the product quality and the retailer can have effective marketing activities to promote the product. One centralized and three decentralized CLSC models are mathematically formulated in this paper. For the centralized CLSC model, the optimal solutions are derived in closed-form format analytically. For three decentralized CLSC models, by assuming the manufacturer is the leader, the equilibrium solutions are also obtained in closed-form format under the Stackelberg game settings. Based on the optimal/equilibrium solutions and the corresponding objective function values for the proposed models, several interesting managerial insights, and economic implications are obtained. Moreover, the proposed models with product quality improvement and marketing efforts are compared with the models with only product quality improvement effort and the models with only marketing effort. The results show that the performance of the proposed models with both product quality improvement and marketing efforts is better in the decentralized CLSC models. [ABSTRACT FROM AUTHOR]

The papers in this special section focus on cyberattacks, strategic cyber-foresight, and security applications. Reports of cyber-attacks against individuals, organizations, and businesses are on the rise. Attackers usually have a deliberate and malicious intent and may involve the criminals taking advantage of flaws in software code, using tricks to get around antivirus tools, and or exploiting unsuspecting users into divulging sensitive information. Often launched by isolated amateurs, or criminals that belong to often well-structured organizations, with money, motivation, and an agenda, such attacks are frequently designed to temporarily or indefinitely disrupt services of a host connected to the internet or simply grind institutional systems to a halt. Popular among social engineering, malwares employed in such attacks are what has come to be known as a distributed denial-of-service attack, which affect the infrastructure of websites, computer servers, and other network resources resulting in the compromise of critical personal or institutional data. Across the globe, these attacks are growing in sophistication, and they tend to have serious economic and security consequences for their targets. The chaos they precipitate can be life-threatening, and their cost can be considerable to target organizations or nations. Such features also affect the dynamics of collaboration among firms, thus posing negative effects on innovation dynamics. [ABSTRACT FROM AUTHOR]

Hybrid ac–dc reconfigurable link technology can find interesting applications in medium-voltage power distribution. These are networks having dc links operating in parallel alongside ac links with post-fault reconfiguration capability. A given system can operate in different configurations while maintaining equivalent capacity during (n−1) contingencies using reconfigurability. This paper provides a method for the ideal selection of the link configuration by defining the efficiency and economic viability boundaries with varying operating power demand and power factor. A sensitivity analysis with parameters such as grid voltage, link length, conductor area, and converter efficiency as well as economic factors such as converter cost and link conductor installation cost is discussed. The study identifies the operating zones wherein the refurbished parallel ac–dc reconfigurable distribution links can be an efficient and economically preferred option of delivering power as compared to a system with only ac or dc links. [ABSTRACT FROM AUTHOR]

This paper proposes a new and comprehensive approach for optimal sizing and placement of a wind farm (WF) in a radial distribution network (RDN) while considering several factors associated with its reliability, operation, economics and environment impact. The consideration of the reliability aspect is essential to correctly assess the impacts of forced outages of wind turbines in the field. In this context, a sequential Monte Carlo simulation-based technique has been formulated to evaluate the performance of the WF with varying capacities at different locations in the RDN. Additionally, the capability of the WF to perform Volt-Var and Volt-Watt control has been capitalized on to provide voltage support to the grid in compliance with international standards (IEEE 1547-2018). Finally, a combination of Analytic Hierarchy Process and Technique for Order Preference by Similarity to Ideal Solution has been used to assess and determine the optimal size and location of the WF, based on a selected set of performance criteria, namely cumulative violations of the steady-state voltage range, cumulative losses in RDN, cumulative violations of the line thermal rating, levelized cost of energy, and reduction in carbon emission. The proposed approach has been validated considering different modes of voltage control on the standard 33-bus RDN system. [ABSTRACT FROM AUTHOR]

Switched reluctance motor (SRM) drives are one competitive technology for traction motor drives. This paper proposes a novel and flexible SRM fault-tolerant topology with fault diagnosis, fault tolerance, and advanced control functions. The converter is composed of a single-phase bridge and a relay network, based on the traditional asymmetrical half-bridge driving topology. When the SRM-driving system is subjected to fault conditions including open-circuit and short-circuit faults, the proposed converter starts its fault-diagnosis procedure to locate the fault. Based on the relay network, the faulty part can be bypassed by the single-phase bridge arm, while the single-phase bridge arm and the healthy part of the converter can form a fault-tolerant topology to sustain the driving operation. A fault-tolerant control strategy is developed to decrease the influence of the fault. Furthermore, the proposed fault-tolerant strategy can be applied to three-phase 12/8 SRM and four-phase 8/6 SRM. Simulation results in MATLAB/Simulink and experiments on a three-phase 12/8 SRM and a four-phase 8/6 SRM validate the effectiveness of the proposed strategy, which may have significant economic implications in traction drive systems. [ABSTRACT FROM AUTHOR]

This paper studies the defense strategy for a parallel system subject to an unintentional impact and an intentional impact. Existing research assumes that system damage is caused by either natural disasters (unintentional impacts) or strategic attackers (intentional impacts). However, in practice, the defender may encounter diverse scenarios, where these two kinds of impacts can happen in a sequential order. Without knowing the precise occurrence sequence, the defender must allocate its limited resources against two successive impacts. In each contest, the defender can construct redundant elements and protect them from damage, to minimize the expected loss from system destructions. Illustrative examples of the optimal strategy are presented in three cases: first, where the unintentional impact comes first; second, where the intentional impact comes first; and third, where the two impacts come in an uncertain order. Supplemental protection is considered in the model extension, where the defender can allocate additional protection resources to those elements that have survived after the first impact. [ABSTRACT FROM AUTHOR]

Interconnection networks lie in the heart of all types of parallel architectures, because how processors or memory modules are connected to each other has a significant impact on the scalability, reliability, cost and performance. For example, a nonblocking interconnection network delivers guaranteed path availability to any connection requests, without interference to existing connections. Also, an interconnection network with multicast capability can distribute data from a single source to all the destinations in a one-shot manner, eliminating unnecessary duplications and minimizing communication delays. However, implementing nonblocking multicast networks imposes great challenges to designers because both of them demand high hardware cost. To deal with this problem, in this paper we propose a novel interconnection network, named Multicast Capable Low-cost Network (MCL), which is both nonblocking for multicast traffic and cost-efficient. We first design the topologies and routing algorithms for MCL, and then prove its nonblocking multicast properties. Most importantly, we show that MCL achieves the lowest hardware cost in terms of asymptotic number of crosspoints. Specifically, the theoretical upper bound on the crosspoints of an $N \times N$ MCL is $O(N \log ^{3.39} N)$ . The explicitly constructed instance of an $N \times N$ MCL has a cost of $O(N^\frac{5}{4})$ and constant delay from the input ports to the output ports. These theoretical and practical costs are both the lowest compared to previous designs which deliver the same performance. [ABSTRACT FROM AUTHOR]

This paper presents an economic model, based on a field-validated load model, for the assessment of impact of conservation voltage reduction (CVR) implemented continuously during both on-peak and off-peak hours. The model evaluates the impact on individual customers and the utility, taking into account the different billing structures, including service class, monthly rates, and reactive power billing. The model considers as well the impact of the utility's revenue decoupling mechanism. The hourly operation of three New York City networks of the Consolidated Edison Company of New York (ConEd) for an entire year has been simulated for the purpose of this study. The results presented for voltage reductions between 2.25% and 8% indicate that for individual customers, the larger the original bill, the greater the relative savings in percentage of the original bill. For the utility, the main advantages are the reduction in aggregated energy consumption and peak power demand with corresponding avoided investment and operating costs. The study and results presented are the first of their kind for a meshed power system. In addition, the economic model presented can be used for any utility system where distribution is separated from generation ownership. [ABSTRACT FROM AUTHOR]

Three-phase unbalance could have significant impacts on the secure and economic operation of a low-voltage distribution system. With the deployment of smart meters and the emergence of phase switch devices (PSDs), more efficient schemes for mitigating three-phase unbalance are expected by utilizing numerous measurement data and the installed PSDs in low-voltage areas. Therefore, a bi-level optimal phase switch device placement model for mitigating three-phase unbalance is proposed in this work. In the upper-level model, the PSD placement strategy is optimized by minimizing the total costs of PSD installation and operation costs of low-voltage areas determined in the lower-level model. In the lower-level model, the operation costs of low-voltage areas for typical days are minimized based on the PSDs and their locations determined in the upper-level model. The proposed bi-level model is tested by an actual low-voltage area of Zhejiang province, China, and the effectiveness of the optimal PSD placement model for reducing the total investment and operation costs of the low-voltage area demonstrated. [ABSTRACT FROM AUTHOR]

The effective pricing of electric vehicle (EV) charging by aggregators constitutes a key problem toward the realization of the significant EV flexibility potential in deregulated electricity systems and has been addressed by previous work through bi-level optimization formulations. However, the solution approach adopted in previous work cannot capture the discrete nature of the EV charging/discharging levels. Although reinforcement learning (RL) can tackle this challenge, state-of-the-art RL methods require discretization of state and/or action spaces and thus exhibit limitations in terms of solution optimality and computational requirements. This article proposes a novel deep reinforcement learning (DRL) method to solve the examined EV pricing problem, combining deep deterministic policy gradient (DDPG) principles with a prioritized experience replay (PER) strategy and setting up the problem in multi-dimensional continuous state and action spaces. Case studies demonstrate that the proposed method outperforms state-of-the-art RL methods in terms of both solution optimality and computational requirements and comprehensively analyze the economic impacts of smart-charging and vehicle-to-grid (V2G) flexibility on both aggregators and EV owners. [ABSTRACT FROM AUTHOR]

The article discusses that the Military-Industrial Complex, as it was called in the U.S., Military- Industrial-Congressional Complex, is an informal, unspoken and under-scrutinized trilateral arrangement of mutual benefit between military, defense contractors, and political institutions. It mentions that legislative branch gets electoral support from special interest groups, which sustains it in power; and uses power to provide political approval for funding for the executive.

Daily headlines stress the ways modern technologies disclose their most dystopian possibilities; this magazine is replete with examples of innovative technologies that prompt considerations of their unethical applications. Numerous approaches have already been proposed to advance critical thinking about the social, cultural, environmental, and economic implications of tech innovation, such as tech literacy and philosophy of technology. What these intellectual traditions have shown is that while the negative effects of technological innovations may be unprecedented, they can be foreseen, and, more importantly, mitigated through more intentional and skillful engineering. Nevertheless, systematic efforts to address these impacts remain peripheral to the engineering profession, with technological artifacts deemed value-neutral, and intervention often seen as luddite and unenforceable. While this situation suggests a need for systemic changes across academic and industry contexts, it also points to an immediate need to address the uptake of critical thinking about the implications of tech innovation within the engineering community. [ABSTRACT FROM AUTHOR]

Survivability of silicon-carbide (SiC) mosfet modules during short circuit (SC) is essential for modern power electronics systems due to large economic implications. SiC mosfet modules exhibit narrow SC withstand times and generally much lower SC robustness than silicon (Si) insulated-gate bipolar transistors (IGBTs). This puts a critical concern on their utilization, further stressing the importance of reliable protection. This article presents a comprehensive analysis and discussion on the SiC mosfet module SC protection and performance comparison between conventional desaturation detection, previously used for Si IGBT protection, and Rogowski switch-current sensor (RSCS) detection. In addition, this article presents the experimental design for soft turn-off as a reaction to the SC detection to avoid excessive overshoots during the abrupt turn-off of the SC current. To perform different types of SC with various fault inductances on different temperatures, and for the sake of fair comparison under the same conditions, a gate-driver unit for 1.2 kV SiC mosfet half-bridge modules is developed containing both detection methods. The results demonstrate that both methods are successful in protecting the module in all SC types, with superiority of the RSCS detection and concerns for desaturation detection in high-inductance and high dc-bus voltage SC events. [ABSTRACT FROM AUTHOR]

The unpredictable and volatile nature of renewable energy sources will increase the burden of a system operator for maintaining the system reliability in different conditions. In this article, a stochastic risk-constrained framework is proposed for short-term optimal scheduling of autonomous microgrids to evaluate the influence of demand response (DR) programs on reliability and economic issues, simultaneously. The objective is to maximize the expected profit of the microgrid operator through optimal scheduling of resources in a more reliable manner considering both supply and demand side uncertainties. In the proposed approach, the microgrid operator's risk aversion is modeled by using the conditional value-at-risk method to control and avoid nondesirable profit distributions due to various system uncertainties. Moreover, ac optimal power flow technique is employed to calculate the amount of energy and reserve of dispatchable distributed generation (DG) units and responsive loads for the operational hour of the next day. Eventually, the applicability of the proposed method is studied on different test systems and impacts of various parameters such as level of DR participants and values of lost load as well as risk aversion parameter on the system's economy and reliability indices are investigated deeply. [ABSTRACT FROM AUTHOR]