130 research outputs found
μ€λ§νΈ 그리λλ₯Ό μν μ λ ₯μ ν΅μ μ μ λ’°μ± ν₯μ κΈ°λ² μ°κ΅¬
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Όλ¬Έ (λ°μ¬)-- μμΈλνκ΅ λνμ : μ κΈ°Β·μ»΄ν¨ν°κ³΅νλΆ, 2014. 8. κΉμ±μ² .μ§κ΅¬ μ¨λν, μ¦κ°νλ μλμ§ μꡬ λ° μ΅λ λΆνμ λ°λ₯Έ μν λ¬Έμ λ±μ ν΄κ²°νκΈ° μν΄, μ€λ§νΈ 그리λ ꡬμΆμ μν λ§μ λ
Έλ ₯λ€μ΄ μ§ν μ€μ΄λ€. μ€λ§νΈ 그리λλ₯Ό ꡬννκΈ° μν΄μλ ν₯μλ μ 보ν΅μ κΈ°μ μ΄ νμνλ©°, μ΄λ ν΅μ λ€νΈμν¬λ₯Ό ν΅ν μμ μ± μλ λ°μ΄ν° μ μ‘ μ¬λΆμ λ¬λ €μλ€. μ€λ§νΈ 그리λλ₯Ό μν μ¬λ¬ ν΅μ κΈ°μ ν보 μ€ μ λ ₯μ ν΅μ (PLC), νΉν μ€μ μ (MV) μ λ ₯μ μμ κ³ μ PLCμ μ§μ€νμλ€. μ λ ₯μ ν΅μ λ€νΈμν¬μ μ λ’°μ±μ μ λ ₯μ μ΄ μ€λ§νΈ 그리λμ ν΅μ λ§€μ²΄λ‘ μ¬λ°λ₯΄κ² λμνκΈ° μν μ κ²° 쑰건μ΄λ€.
λ³Έ λ
Όλ¬Έμμλ μ λ ₯μ ν΅μ μ λ³΄λ€ μ λ’°μ± μκ³ κ°κ±΄νκ² λ§λ€κΈ° μν λ°©μμ λνμ¬ μ°κ΅¬νλ€. μ΄λ₯Ό μν΄ OFDM κΈ°λ°μ μ λ ₯μ ν΅μ μμ€ν
μμ μ΅λλΉν©μ± (MRC) λ€μ΄λ²μν° κ΅¬μ‘°λ₯Ό κ³ μνλ€. μ΄λ¬ν μμ€ν
μμ μ΅λλΉν©μ± λ€μ΄λ²μν° μ΄λμ μ΅λννκΈ° μν μ΅μ μ λΆλ°μ‘ν νμ΄λ§ (subcarrier pairing) κΈ°λ²μ μ μνλ€. λͺ¨μμ€νμ ν΅ν΄ μ μνλ κΈ°λ²μ μ±λ₯ ν₯μ μ¬λΆλ₯Ό κ²μ¦νλ€.
λ€μ΄λ²μν° μ΄λμ μ£Όνμ ν¨μ¨μ κ°μλ₯Ό μ λ°νλ€. μμ μ μλ λΆλ°μ‘ν νμ΄λ§ κΈ°λ²μΌλ‘ μΈν΄ λ³Έμ§μ μΌλ‘ λ°μνλ μ£Όνμ ν¨μ¨ κ°μλ₯Ό ν΄κ²°νκΈ° μν΄, 무μ MIMO μ±λμ μ μ²λ¦¬ (precoding) κΈ°λ²μ μ μ©νλ€. λͺ¨μμ€ν κ²°κ³Όλ₯Ό ν΅ν΄, λμ λ³μ‘° μ§μλ‘ νμ΄λ§ κΈ°λ²μ μ΄μ©νλ κ²μ΄ λ§€μ° λ§μ κ³μ°λμ΄ νμν μ μ²λ¦¬ κΈ°λ²κ³Ό λΉκ΅νμ¬ μ μ¬ν μ±λ₯μ λνλμ μ μ μλ€.
λ€μμΌλ‘ μ΅λλΉν©μ± κΈ°λ° μ΅μ λΆλ°μ‘ν νμ΄λ§ κΈ°λ²μ μ λ ₯μ /무μ λ€μ΄λ²μν° μμ€ν
μ νμ₯νλ€. μ΄ μμ€ν
μμ μ λ ₯μ κ³Ό 무μ μμ€ν
μ κ° λΆλ°μ‘νλ€μ μ§μ μ΄λ£¨μ΄ μ΅λλΉν©μ±μ μννλ€. μ 체 λ°μ΄ν° μ μ‘λ₯ μ μ΅λννκΈ° μν΄ μκ³Ό μ μ¬ν μ΅μ λΆλ°μ‘ν νμ΄λ§ κΈ°λ²μ μ μνλ€. λͺ¨μμ€ν κ²°κ³Όλ₯Ό ν΅ν΄ μ μλ κΈ°λ²μ΄ λ°μ΄ν° μ μ‘λ₯ κ³Ό μμν°μ§ νλ₯ μΈ‘λ©΄μμ μλΉν μ±λ₯ ν₯μμ λνλΈλ€.To solve the problems of global warming effects, rising energy-hungry demands, and risks of peak loads, many efforts to build a Smart Grid system are underway. A smart grid requires advanced information, and communication technologies to support its intelligent features, and it depends on the reliable data transmission via a communication network. Among the candidates of communication technology for smart grid, we focus on a power line communications (PLC), especially a broadband PLC over a medium voltage (MV) powerline network. The reliability of the PLC network are prerequisite for an appropriate communication medium for smart grid.
This dissertation considers a strategy to make the PLC network more reliable and robust. We consider a maximal ratio combining (MRC) diversity scheme for a power line orthogonal frequency division multiplexing (OFDM) system. An optimal subcarrier pairing scheme is proposed to maximize the MRC gain. Numerical results are presented to verify that the proposed scheme provides enhanced performance.
Diversity gain comes at the expense of spectral loss. We adopt the precoding scheme proposed for wireless MIMO system to compensate the spectral loss due to the inherent transmission mechanism of the above subcarrier pairing scheme. It is shown that the proposed pairing scheme with higher modulation order achieves a comparable performance to the precoding scheme which requires high computational cost.
We extend the optimal subcarrier pairing with MRC approach to powerline/wireless diversity system, where the powerline and wireless subcarriers are paired to perform maximal ratio combining (MRC). An similar optimal subcarrier pairing scheme is proposed to maximize the data rate for MRC reception in powerline/wireless diversity OFDM systems. Numerical results show that, by using the proposed optimal subcarrier pairing, significant performance enhancement can be achieved in terms of Ergodic data rate and outage probability.1 Introduction 1
1.1 Smart Grid 1
1.2 Communication and Networking in the Smart Grid 5
1.2.1 Network Topologies 6
1.2.2 Communication Technologies for the Smart Grid 8
1.3 Dissertation Outline 11
2 Power Line Communications for Smart Grid 12
2.1 Power Line Channel Characteristics 15
2.2 PLC Channel Modeling 15
2.3 PLC Channel Noise Characteristics 17
2.4 MV Channel Description for This Dissertation 19
2.4.1 Implementation of Powerline Channel 19
2.4.2 Typical Topology 22
2.5 MV Powerline Noise 25
3 Optimal Subcarrier Pairing for Maximal Ratio Combining in OFDM Power Line Communications 27
3.1 Motivation 27
3.2 Optimal Subcarrier Pairing for Maximal Ratio Combining 28
3.2.1 System Model 28
3.2.2 Optimal Subcarrier Pairing 31
3.3 Numerical Results 33
3.3.1 Simulation Environments 33
3.3.2 SER Performance Analysis 35
3.3.3 Performance Comparison with Equal Gain Combining 38
3.4 Precoding Scheme to Compensate Spectral Loss Due to Diversity Transmission 40
3.4.1 Review of the Minimum Distance-Based Precoder for MIMO Spatial Multiplexing Systems 41
3.4.2 Optimal Minimum Distance-Based Precoder for QPSK Constellation 41
3.4.3 Application to PLC OFDM System 44
3.4.4 Performance Comparison of max-dmin Precoder for QPSK Modulation 44
3.4.5 Performance Comparison of max-dmin Precoder for 16-QAM Modulation 49
3.4.6 Complexity Analysis 53
3.5 Conclusion 53
4 Optimal Subcarrier Pairing for MRC in Powerline/Wireless Diversity OFDM Systems 55
4.1 Motivation 55
4.2 Powerline/Wireless Diversity OFDM Systems 57
4.3 Optimal Subcarrier Pairing for Powerline/Wireless Diversity 60
4.4 Numerical Results 62
4.4.1 Channel Models 63
4.4.2 Performance Comparison 67
4.5 Conclusion 76
5 Concluding Remarks 77
5.1 Summary 77
5.2 Future Works 78Docto
Effect of water on electrical properties of Refined, Bleached, and Deodorized Palm Oil (RBDPO) as electrical insulating material
This paper describes the properties of refined, bleached, deodorized palm oil (RBDPO) as having the potential to be used as insulating liquid. There are several important properties such as electrical breakdown, dielectric dissipation factor, specific gravity, flash point, viscosity and pour point of RBDPO that was measured and compared to commercial mineral oil which is largely in current use as insulating liquid in power transformers. Experimental results of the electrical properties revealed that the average breakdown voltage of the RBDPO sample, without the addition of water at room temperature, is 13.368 kV. The result also revealed that due to effect of water, the breakdown voltage is lower than that of commercial mineral oil (Hyrax). However, the flash point and the pour point of RBDPO is very high compared to mineral oil thus giving it advantageous possibility to be used safely as insulating liquid. The results showed that RBDPO is greatly influenced by water, causing the breakdown voltage to decrease and the dissipation factor to increase; this is attributable to the high amounts of dissolved water
Power Quality in Electrified Transportation Systems
"Power Quality in Electrified Transportation Systems" has covered interesting horizontal topics over diversified transportation technologies, ranging from railways to electric vehicles and ships. Although the attention is chiefly focused on typical railway issues such as harmonics, resonances and reactive power flow compensation, the integration of electric vehicles plays a significant role. The book is completed by some additional significant contributions, focusing on the interpretation of Power Quality phenomena propagation in railways using the fundamentals of electromagnetic theory and on electric ships in the light of the latest standardization efforts
LUX-ZEPLIN (LZ) Technical Design Report
In this Technical Design Report (TDR) we describe the LZ detector to be built at the Sanford Underground Research Facility (SURF). The LZ dark matter experiment is designed to achieve sensitivity to a WIMP-nucleon spin-independent cross section of three times ten to the negative forty-eighth square centimeters
Optimization Methods Applied to Power Systems β ‘
Electrical power systems are complex networks that include a set of electrical components that allow distributing the electricity generated in the conventional and renewable power plants to distribution systems so it can be received by final consumers (businesses and homes). In practice, power system management requires solving different design, operation, and control problems. Bearing in mind that computers are used to solve these complex optimization problems, this book includes some recent contributions to this field that cover a large variety of problems. More specifically, the book includes contributions about topics such as controllers for the frequency response of microgrids, post-contingency overflow analysis, line overloads after line and generation contingences, power quality disturbances, earthing system touch voltages, security-constrained optimal power flow, voltage regulation planning, intermittent generation in power systems, location of partial discharge source in gas-insulated switchgear, electric vehicle charging stations, optimal power flow with photovoltaic generation, hydroelectric plant location selection, cold-thermal-electric integrated energy systems, high-efficiency resonant devices for microwave power generation, security-constrained unit commitment, and economic dispatch problems
Numerical and Analytical Methods in Electromagnetics
Like all branches of physics and engineering, electromagnetics relies on mathematical methods for modeling, simulation, and design procedures in all of its aspects (radiation, propagation, scattering, imaging, etc.). Originally, rigorous analytical techniques were the only machinery available to produce any useful results. In the 1960s and 1970s, emphasis was placed on asymptotic techniques, which produced approximations of the fields for very high frequencies when closed-form solutions were not feasible. Later, when computers demonstrated explosive progress, numerical techniques were utilized to develop approximate results of controllable accuracy for arbitrary geometries. In this Special Issue, the most recent advances in the aforementioned approaches are presented to illustrate the state-of-the-art mathematical techniques in electromagnetics
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