Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
1,286
result(s) for
"Electric networks, Active."
Sort by:
Coupled-oscillator based active-array antennas
\"This book presents the theory of phased array antennas that use arrays of electronic oscillators coupled to each other so as to mutually injection lock and thus oscillate as an ensemble. This arrangement provides a remarkably simple beam steering control system replacing the complicated array of computer controlled phase shifters traditionally used for this purpose. The book also describes a large number of laboratory demonstrations that have been reported over the past three decades that experimentally verify the various aspects of the theory. The theory is initially presented using a linear approximation permitting derivation of much of the array behavior analytically. Then, at a deeper level, a nonlinear formulation is used to obtain, computationally, more detailed aspects of the array behavior. The primary purpose of the book is to gather the salient results of the past ten to fifteen years of research in this area into one convenient volume providing both a tutorial explanation of this approach to phased array control and a guide to the literature on the subject\"--
eBook
Decentralized Emergency Control of AC Power Grid Modes with Distributed Generation
Large-scale development of small-scale generation, and facilities based on this, with their integration into existing distribution networks, qualitatively change the modes and tasks of network management and transform previously passive electric networks into active ones. Features of parameters and modes of small-scale generation, insufficient observability and manageability in centralized management determine the need to use a decentralized multi-agent control of the modes of such networks. First of all, this applies to emergency management, which includes automatic restoration of the integrity and normal operation of the network. This paper presents a set of specialized methods for emergency management of active power grid modes and the results of a study of their effectiveness on mathematical and physical models that confirm the feasibility of using decentralized emergency management and network recovery management. In particular, this includes: a method of emergency proactively balanced separation of grid energy districts along one of the a priori fixed network cross-sections in the event of disturbances with the transition to island mode, and a method for two-stage restoration of the integrity and normal network mode with decentralized synchronization of active parts on remote network switches. In the case of the decentralized remote synchronization of active parts, it is proposed to use special control of the excitation and speed of generators to create conditions for the successful operation of automatic reclosing devices with synchronization detection. It is essential for emergency management in active networks with small generation to reject the concept of ensuring the reliability of power supply through maintaining the integrity of the network in favor of the concept of an emergency-balanced breakdown of the network into balanced areas with the subsequent automatic restoration of integrity. To conduct research on the physical model, a prototype of distributed system emergency automation has been developed that does not use data transmission tools, which ensures its high cybersecurity and the feasibility of decentralized management.
Journal Article
Coordinated Control of Single-Phase End-Users for Phase Load Balancing in Active Electric Distribution Networks
In the paper, a coordinated control methodology of single-phase (1-P) end-users switching operations on the phases of an active electric distribution network (AEDN) has been proposed to obtain a minimum unbalance degree at the coupling common point (CCP) level with the main distribution system. The phase load balancing (PLB) process considers the smart devices that switch the 1-P end-users (consumers and prosumers) from one phase to another to compensate for the phase load unbalance. The proposed methodology has been tested successfully in an AEDN belonging to a Romanian Distribution Network Operator (DNO) containing 114 end-users (104 consumers/10 prosumers) integrated into the Smart Metering System (SMS). The optimal solution leads to a value of the objective function by 1.00, represented by the unbalance factor (UF), which could be identified with the ideal target. A comparative analysis was conducted considering other possible PLB cases (the consumer-level PLB and prosumer-level PLB), obtaining similar values of the UF (1.027 vs. 1.028), slightly higher than in the hybrid-level PLB. Additionally, the significant technical benefits were quantified through an energy-saving of 58.73% and decreasing the phase voltage unbalance rate by 91% compared to the initial case (without PLB). These results emphasized the positive impact of the proposed coordinated control methodology on the PLB process and evidenced its effectiveness and applicability in the AEDNs.
Journal Article
Technical and Economic Model of the Conductor Cross-Section for Active-adaptive Electrical Networks
There can be observed a gradual transition of the electric power industry to the innovative technology platform âSmart Gridâ around the world; in Russia it is done on the platform of an intelligent electrical grid with an active-adaptive network, which becomes one of the most important subsystems. There are new elements of power transmission lines, among which new generation conductors (NGC) are being actively introduced. However, the high cost of innovations in the power grid complex makes their use quite slow. The conductor cross-section is the most significant parameter of the power transmission line; it determines its main technical and economic indicators. The problem of choosing economically reasonable conductor cross-sections stems from the need to ensure the required level of reliability of power transmission lines, determines the most effective way to invest money and reduce the cost of electricity transportation. Modern requirements for the feasibility study of design solutions increase the economic significance of the problem to determine the economically feasible conductor cross-sections for the power transmission lines. At the same time, there is no method for choosing the optimal conductor cross-sections of NGC. An incorrect choice of the conductor brand and its cross-section can lead to unjustified costs for the construction and reconstruction of power transmission lines and increase the cost of electricity transmission. In the article there is the analysis of existing methods of project decisions feasibility; it was taken as the basis to develop the technical and economic model of a conductor cross-section for active-adaptive electrical grids, taking into account the thermal model of the conductor and the random nature of the change of current running through the power transmission lines.
Journal Article
Active Filters for Integrated-Circuit Applications
This authoritative resource offers you comprehensive knowledge and detailed design guidance on active filters for integrated-circuit applications. The book identifies common problem areas, reviews circuit analysis operations, and thoroughly illustrates the concept of feedback. You learn the state variable procedure - a general design approach that is appropriate for a wide range of applications. The book also discusses classic approaches such as cascade and biquad circuits for comparative purposes. This unique resource features a case study for two operational amplifier designs that illustrates key challenges that need to be overcome. The book presents a multitone procedure for the simulated testing of switched capacitor designs, and teaches you how to find desired pre-corrected network functions that can be implemented to meet arbitrary specifications. Other key topics examined include sensitivity considerations, leapfrog architecture, and critical frequency distortion due to the switched capacitor integrator.
eBook
Optimal integration of DGs into radial distribution network in the presence of plug-in electric vehicles to minimize daily active power losses and to improve the voltage profile of the system using bio-inspired optimization algorithms
Purpose
The increase in plug-in electric vehicles (PEVs) is likely to see a noteworthy impact on the distribution system due to high electric power consumption during charging and uncertainty in charging behavior. To address this problem, the present work mainly focuses on optimal integration of distributed generators (DG) into radial distribution systems in the presence of PEV loads with their charging behavior under daily load pattern including load models by considering the daily (24 h) power loss and voltage improvement of the system as objectives for better system performance.
Design/methodology/approach
To achieve the desired outcomes, an efficient weighted factor multi-objective function is modeled. Particle Swarm Optimization (PSO) and Butterfly Optimization (BO) algorithms are selected and implemented to minimize the objectives of the system. A repetitive backward-forward sweep-based load flow has been introduced to calculate the daily power loss and bus voltages of the radial distribution system. The simulations are carried out using MATLAB software.
Findings
The simulation outcomes reveal that the proposed approach definitely improved the system performance in all aspects. Among PSO and BO, BO is comparatively successful in achieving the desired objectives.
Originality/value
The main contribution of this paper is the formulation of the multi-objective function that can address daily active power loss and voltage deviation under 24-h load pattern including grouping of residential, industrial and commercial loads. Introduction of repetitive backward-forward sweep-based load flow and the modeling of PEV load with two different charging scenarios.
Journal Article
Comparative framework for AC-microgrid protection schemes: challenges, solutions, real applications, and future trends
With the rapid development of electrical power systems in recent years, microgrids (MGs) have become increasingly prevalent. MGs improve network efficiency and reduce operating costs and emissions because of the integration of distributed renewable energy sources (RESs), energy storage, and source-load management systems. Despite these advances, the decentralized architecture of MGs impacts the functioning patterns of the entire system, including control strategy, energy management philosophy, and protection scheme. In this context, developing a convenient protection strategy for MGs is challenging because of various obstacles, such as the significant variance in short-circuit values under different operating modes, two-way power flow, asynchronous reclosing, protection blinding, sympathetic tripping, and loss of coordination. In light of these challenges, this paper reviews prior research on proposed protection schemes for AC-MGs to thoroughly evaluate network protection's potential issues. The paper also provides a comprehensive overview of the MG structure and the associated protection challenges, solutions, real applications, and future trends.
Journal Article
Network reconfiguration and DG based compensation of Wolaita Sodo distribution system by using particle swarm optimisation
Improving voltage profiles and reducing power losses are critical challenges in modern distribution systems, especially in real, unbalanced and weakly interconnected grids. This study presents a novel application of simultaneous network reconfiguration and distributed generation (DG) placement using Particle Swarm Optimization (PSO) to the Wolaita Sodo distribution network in Ethiopia. Unlike most prior works conducted on IEEE standard feeders, this research uses actual network topology, load data, conductor parameters and operational constraints from a real Ethiopian distribution system. The optimization problem considers radiality constraints, DG size limits and voltage and current limits, with objectives of minimizing active/reactive power losses, improving voltage profiles and maximizing economic benefits. A backward-forward sweep load flow method evaluates network performance under four scenarios: base case, reconfiguration only, DG placement only and simultaneous implementation. Results show that the proposed method reduces active power losses by 72.064%, decreases voltage deviation from 24.63% to 4.5% and improves the minimum bus voltage from 0.7537 pu to 0.9550 pu. The annual financial savings of 16.3956 million ETB yield a payback period of six years. This grouping of real-network data, simultaneous optimization, and integrated techno-economic analysis offers a practical and replicable decision-support tool for utilities in emerging power systems.
Journal Article
Evaluation of the Operating Modes of the Urban Electric Networks in Dushanbe City, Tajikistan
Currently, energy saving has become an acute problem all over the world. Due to the rapid development of both the energy and information technology sectors, as well as an increase in the electricity demand, the electric distribution system is facing problems caused by stricter requirements for electricity quality, reliability, efficiency, and sustainability. Therefore, the use of energy-saving technologies, both the improvement of existing ones and the application of new ones, is one of the main reserves for electricity saving in power supply systems. This study is devoted to the evaluation of the operating modes of transformer substations of the 6–10 kV electric distribution network in Dushanbe city, based on the results of control winter measurements and the dependence of the low coefficient of active power in transformer substations. It has been observed that, with a low coefficient of active power in transformer substations, when transmitting electricity from substation busbars to transformer substations of a final consumer via overhead transmission lines (an average length of 5 km), the voltage loss exceeds the maximum permissible values. When transmitting electricity via cable lines, the voltage losses are within the limit of 5%. However, a low active power factor may be the reason for an increase in capacitive currents, followed by the command of single-phase earth fault currents. Due to the low active power factor, the increase in voltage losses and useful power losses leads to the inefficient operating modes of the transformer substations.
Journal Article