Harmonic Analysis of Non-Sinusoidal Harmonic Signals in Electric Power System

2014 ◽  
Vol 1070-1072 ◽  
pp. 779-784
Author(s):  
Dan Luo ◽  
Yi Xiao ◽  
Jie Na Zhou
Keyword(s):  
Power System ◽  
Harmonic Analysis ◽  
Short Range ◽  
Time Windows ◽  
Electric Power System ◽  
Normal Operation ◽  
Calculation Error ◽  
Interpolation Algorithm ◽  
Harmonic Signals ◽  
And Control

Harmonic Analysis and control is very important for the power system because harmonics have serious harm to its normal operation. Harmonic Analysis uses fast Fourier transform (FFT) to solve this problem though it causes the spectrum leakage which Increases the calculation error. To solve this problem, the interpolation algorithm combine with tapered time windows are used. The tapered time windows solve the long-range leakage and the interpolation algorithm solves the problem of short-range leakage.

scholarly journals Study on Impedance Characteristics of Aircraft Cables

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Weilin Li ◽  
Wenjie Liu ◽  
Xiaobin Zhang ◽  
Zhaohui Gao ◽  
Meng Xie ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Power System ◽  
Electric Power ◽  
Electrical Equipment ◽  
Electric Power System ◽  
Normal Operation ◽  
Variable Frequency ◽  
Forming Mechanism ◽  
Changing Trends ◽  
Impedance Characteristics

Voltage decrease and power loss in distribution lines of aircraft electric power system are harmful to the normal operation of electrical equipment and may even threaten the safety of aircraft. This study investigates how the gap distance (the distance between aircraft cables and aircraft skin) and voltage frequency (variable frequency power supply will be adopted for next generation aircraft) will affect the impedance of aircraft cables. To be more precise, the forming mechanism of cable resistance and inductance is illustrated in detail and their changing trends with frequency and gap distance are analyzed with the help of electromagnetic theoretical analysis. An aircraft cable simulation model is built with Maxwell 2D and the simulation results are consistent with the conclusions drawn from the theoretical analysis. The changing trends of the four core parameters of interest are analyzed: resistance, inductance, reactance, and impedance. The research results can be used as reference for the applications in Variable Speed Variable Frequency (VSVF) aircraft electric power system.

Dynamic Modelling of Wind Farm Grid Interaction

2002 ◽  
Vol 26 (4) ◽  
pp. 191-210 ◽  
Author(s):  
Anca D. Hansen ◽  
Poul Sørensen ◽  
Frede Blaabjerg ◽  
John Becho
Keyword(s):  
Power System ◽  
Wind Farm ◽  
Control Strategies ◽  
Dynamic Modelling ◽  
Normal Operation ◽  
Simulation Tool ◽  
Power System Simulation ◽  
Collection System ◽  
Wind Model ◽  
And Control

This paper describes a dynamic model of a wind farm and its nearest utility grid. It is intended to use this model in studies addressing the dynamic interaction between a wind farm and a power system, both during normal operation of the wind farm and during transient grid fault events. The model comprises the substation where the wind farm is connected, the internal power collection system of the wind farm, the electrical, mechanical and aerodynamic models for the wind turbines, and a wind model. The integrated model is built to enable the assessment of power quality and control strategies. It is implemented in the commercial dedicated power system simulation tool DIgSILENT.

scholarly journals Investigating Phase Over-Current (OC) Protection in Medium-Voltage networks

2019 ◽  
Vol 4 (6) ◽  
pp. 41-49 ◽  
Author(s):  
Aniagboso John Onah
Keyword(s):  
Power System ◽  
Electric Power ◽  
Electric Power System ◽  
Normal Operation ◽  
Electrical Network ◽  
Power Circuit ◽  
Medium Voltage ◽  
Protection Scheme ◽  
Overcurrent Protection ◽  
Overcurrent Relays

Overcurrent protection is protection against excessive currents or current beyond the acceptable current rating of equipment. It generally operates instantly. Short circuit is a type of overcurrent. Magnetic circuit breakers, fuses and overcurrent relays are commonly used to provide overcurrent protection. There is always a need to protect expensive power equipment. Protective relaying is a very important part of any electric power system that comes into play during trouble, fault or abnormal condition. The purpose is to isolate unhealthy part of electrical power system while the rest continue their normal operation. The entire electric power system from source to load centers is exposed and subject to natural hazards. The effects of these hazards are capable of interrupting normal operations of the system. Since these hazards cannot be prevented, precautions are taken to minimize or eliminate their effect on the system. The relay is a basic component of any protection scheme. The information (or signals) received from the power system actuates the relay, when necessary, to perform one or more switching actions. The signals are proportional to the magnitudes and phase angles of power system voltages and currents. When the relay receives these signals, it decides to close (or open) one or more sets of normally open (or closed) contacts, and consequently, the trip coil of a circuit breaker will be energized to open the power circuit. This paper investigates over-current relay protection scheme applied to medium-voltage electrical network. Methods of current and time grading have been applied in the coordination of the overcurrent relays in a radial network. Different time/current characteristics of relays such as the normal inverse (NI), very inverse (VI), and extreme inverse (EI) have been examined in order to obtain optimum discrimination.

Management and Control of a Small-Scale Eolian Electric Power System

2020 ◽  
Author(s):  
Festila Clement ◽  
Dulf Eva-Henrietta ◽  
Rusu-Both Roxana ◽  
Chetan Sergiu ◽  
Cirlugea Mihaela
Keyword(s):  
Power System ◽  
Electric Power ◽  
Electric Power System ◽  
Small Scale ◽  
And Control
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