19,970 research outputs found

    Recent Sikorsky R and D progress

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    The recent activities and progress in four specific areas of Sikorsky's research and development program are summarized. Since the beginning of the S-76 design in 1974, Sikorsky has been aggressively developing the technology for using composite materials in helicopter design. Four specific topics are covered: advanced cockpit/controller efforts, fly-by-wire controls on RSRA/X-Wing, vibration control via higher harmonic control, and main rotor aerodynamic improvements

    Implementing UPQC based Intelligent Islanding for the Microgrid System

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    Increased penetration of small scale renewable energy sources in the electrical distribution network, improvement of power quality has become more critical than where the current harmonics or disturbances and level of voltage can vary widely. For this reason, Custom Power Devices (CPDs) such as the Unified Power Quality Conditioner (UPQC) can be the most appropriate solution used for improving the dynamic performance of the distribution network, where accurate prior knowledge may not be available. Therefore, the main objectives are (i) placement (ii) integration (iii) capacity enhancement and (iv) real time control of the Unified Power Quality Conditioner (UPQC) to improve the power quality of a distributed generation (DG) network connected to the grid or microgrid. A new integration method of the UPQC has been developed: helps to the DGs to deliver quality of power in the case of islanding and help to reintegrate with the grid seamlessly post fault. It perform both control operation such as Detection of Islanding and reconnection techniques, hence, it is termed UPQC?G. The DG Inverter with storage supplies the active fundamental power only and the shunt part of the UPQC compensates the reactive and harmonic power of the load during both interconnected and islanding mode

    Load-ability Analysis during Contingency with Unified Power Flow Controller Using Grey Wolf Optimization Technique

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    Voltage stability enhancement with optimal placement of a unified power flow controller considering load-ability analysis is investigated in this paper. It is essential, because when voltage instability is left unattended, it leads to voltage collapse and, consequently, in a partial or total blackout of the whole network resulting from cascading effect. The optimization process is achieved by increasing the percentage load demand index to the maximum load-ability and under single contingency. This method will be of great benefits to bulk dispatcher of power to plan ahead of how to wheel and deliver power to the end-users during both normal and contingency conditions at the least cost and time. A grey wolf optimization technique is utilised to find the optimal location and sizing of UPFC on the network. The line’s voltage stability and load margin are then evaluated with and without UPFC under different loading conditions using optimal power flow technique. The approach’s effectiveness is carried out on 31-bus, 330kV Nigeria National Grid (NNG) based on two scenarios: load-ability analysis under maximum loading of the network and load-ability analysis under single contingency. The results show that power can be transmitted to meet the growing energy demand over an existing network during normal and contingency conditions without violating voltage stability by making use of the proposed method in this pape

    Power Quality Improvement of Distributed Generation Integrated Network with Unified Power Quality Conditioner.

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    With the increased penetration of small scale renewable energy sources in the electrical distribution network, maintenance or improvement of power quality has become more critical than ever where the level of voltage and current harmonics or disturbances can vary widely. For this reason, Custom Power Devices (CPDs) such as the Unified Power Quality Conditioner (UPQC) can be the most appropriate solution for enhancing the dynamic performance of the distribution network, where accurate prior knowledge may not be available. Therefore, the main objective of the present research is to investigate the (i) placement (ii) integration (iii) capacity enhancement and (iv) real time control of the Unified Power Quality Conditioner (UPQC) to improve the power quality (PQ) of a distributed generation (DG) network connected to the grid or microgrid

    Deep Space Network information system architecture study

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    The purpose of this article is to describe an architecture for the Deep Space Network (DSN) information system in the years 2000-2010 and to provide guidelines for its evolution during the 1990s. The study scope is defined to be from the front-end areas at the antennas to the end users (spacecraft teams, principal investigators, archival storage systems, and non-NASA partners). The architectural vision provides guidance for major DSN implementation efforts during the next decade. A strong motivation for the study is an expected dramatic improvement in information-systems technologies, such as the following: computer processing, automation technology (including knowledge-based systems), networking and data transport, software and hardware engineering, and human-interface technology. The proposed Ground Information System has the following major features: unified architecture from the front-end area to the end user; open-systems standards to achieve interoperability; DSN production of level 0 data; delivery of level 0 data from the Deep Space Communications Complex, if desired; dedicated telemetry processors for each receiver; security against unauthorized access and errors; and highly automated monitor and control

    OPTIMAL PLACEMENT OF UNIFIED POWER FLOW CONTROLLER ON POWER SYSTEM FOR VOLTAGE STABILITY ENHANCEMENT USING ARTIFICIAL NEURAL NETWORK TECHNIQUE

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    The desire for an enhanced power transfer capability and quality of electricity delivered to the customers has led to emergence of Flexible Alternating Current Transmission Systems (FACTS). This work compares power system voltage stability with and without compensation. The compensation is done by optimal placement of Unified Power Flow Controller (UPFC) using Artificial Neural Network (ANN) technique. The algorithm to implement the stabilizing processes employed Newton-Raphson-based load flow equations in MATLAB R2018a environment. The stability of Nigerian 330 kV, 30–bus network was assessed before and after the implementation of UPFC and UPFC-ANN controlled. The results obtained without compensation showed: New Haven, Onitsha, Gombe, Jos, Kano and Calabar with voltage magnitude of 0.9003, 0.9468, 0.6608, 0.8141, 0.8138 and 0.9319 p.u, respectively violated the statutory limit of 0.951.05 p.u and total active power loss was 218.76 MW. With UPFC on bus Calabar, the total active power loss reduced to 200.85 MW, while buses New Haven, Gombe, Jos and Kano produced voltage magnitude of 0.9130, 0.6608, 0.8141 and 0.8138 p.u, respectively, still constrained. ANN based UPFC placement on bus Gombe - the most critical bus with Voltage stability index (VSI) of 0.9252, the voltage magnitude of buses New Haven, Onitsha, Gombe, Jos, Kano and Calabar enhanced to 0.9533, 0.9552, 1.0481, 1.0399, 1.0425 and 1.0081 p.u, respectively and total active power loss reduced by 28.81% compared with 8.19% reduction with UPFC. The study revealed ANN controlled UPFC is suitable and appropriate for improving voltage stability and reducing power loss on power system

    Will SDN be part of 5G?

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    For many, this is no longer a valid question and the case is considered settled with SDN/NFV (Software Defined Networking/Network Function Virtualization) providing the inevitable innovation enablers solving many outstanding management issues regarding 5G. However, given the monumental task of softwarization of radio access network (RAN) while 5G is just around the corner and some companies have started unveiling their 5G equipment already, the concern is very realistic that we may only see some point solutions involving SDN technology instead of a fully SDN-enabled RAN. This survey paper identifies all important obstacles in the way and looks at the state of the art of the relevant solutions. This survey is different from the previous surveys on SDN-based RAN as it focuses on the salient problems and discusses solutions proposed within and outside SDN literature. Our main focus is on fronthaul, backward compatibility, supposedly disruptive nature of SDN deployment, business cases and monetization of SDN related upgrades, latency of general purpose processors (GPP), and additional security vulnerabilities, softwarization brings along to the RAN. We have also provided a summary of the architectural developments in SDN-based RAN landscape as not all work can be covered under the focused issues. This paper provides a comprehensive survey on the state of the art of SDN-based RAN and clearly points out the gaps in the technology.Comment: 33 pages, 10 figure
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