Determination of the Primary Time Constant of the DC Component of the Short Circuit Current Using the AC Component Parameters

2020 ◽  
Author(s):  
Vladislav Novobritsky ◽  
Denis Fedosov
Keyword(s):  
Time Constant ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Dc Component

Research on Adaptive Current Protection of Wind Farm

2012 ◽  
Vol 260-261 ◽  
pp. 257-262
Author(s):  
Feng Ting Li ◽  
Chang Sheng Su
Keyword(s):  
Wind Farm ◽  
Short Circuit ◽  
High Sensitivity ◽  
Short Circuit Current ◽  
Phase Selection ◽  
Wind Generators ◽  
Attenuation Characteristic ◽  
Sample Data ◽  
Dc Component ◽  
Current Sample

In allusion to the problems of convention current protection when it was used to collect circuit of wind farm, the relay protection should consider the short-circuit current of wind generators; The principle of adaptive current protection was described, the fault current and attenuation characteristic of asynchronous wind generator was studied, the scheme of adaptive current protection was proposed for wind farm operation. Taking PSCAD/EMTDC as the platform, simulation and record the voltage and current sample-data of different wind farm operation which can guarantee high sensitivity phase selection, the high accuracy wind generators impedance measure method based on FFT filter DC component is presented , and using MATLAB program achieved the scheme of adaptive current protection. Simulation results demonstrate that collect circuit adaptive current protection is adaptive wind farm operation model, and enhance the operation benefit of wind farm.

Development of a Low Cost Device for Measuring Solar Irradiance

2012 ◽  
Vol 457-458 ◽  
pp. 1377-1382
Author(s):  
Yu Jie Chen ◽  
Cong Hu ◽  
Yi Ze Sun ◽  
Zhuo Meng
Keyword(s):  
Solar Irradiance ◽  
Low Cost ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Solar Irradiation ◽  
Photoelectric Cell ◽  
Cost System ◽  
Different Temperatures ◽  
The Cost

For a determination of the system’s efficiency and decrease the cost, a low cost system for measuring solar irradiance is designed. By analyzing the influence of solar irradiance and temperature to solar cell, we have found that in case of different temperatures the variation of short-circuit current (Isc) in function of solar irradiation incident (E) is always linear. Then the read-out circuitry is designed to measure and convert the signal which is detected by the photoelectric cell and thermocouples. At last, the software is developed to compensate the temperature and make sure the device work normally. The results of detecting the system show that it’s effective and reliable.

scholarly journals The.main types of wind turbines-generators in the power supply system

2022 ◽  
Vol 23 (5) ◽  
pp. 71-85
Author(s):  
V. A. Novobritsky ◽  
D. S. Fedosov
Keyword(s):  
Second Harmonic ◽  
Short Circuit ◽  
Separation Of Variables ◽  
Harmonic Component ◽  
Relay Protection ◽  
Short Circuit Current ◽  
Current Transformer ◽  
Correct Operation ◽  
Protection Devices ◽  
Dc Component

THE PURPOSE. This paper considers the problem of relay protection functioning when the current transformer reaches the saturation mode which is provided by transient processes.METHODS. MATLAB Simulink software environment allows reproducing the method of statespace representation by using structural blocks. The model is verified by comparison the time to saturation, obtained by calculation and according to the graphical data of the model. The separation of variables method extracts and graphically displays the investigated components.RESULTS. This paper reveals that applying the requirements of IEC 61869-2:2012 standard, which determines the worst combination of series of unfavorable factors for current transformers in transient mode, can influence a serious impact on the correct operation of relay protection based on current, reactance or differential principle of action. Saturation of the current transformer can lead to both negative results: false operation of relay protection devices and their failure.CONCLUSION. According to the results of the study, it was determined that the presence of a DC component in the primary short-circuit current has the greatest effect on the protection operation. The delays in the restoration of the RMS value of the short-circuit current reached up to 0.3 seconds, which is comparable with the response time of the second protection zones for microprocessor-based relay protection devices. The DC component of the primary current and the presence of residual magnetic induction of the current transformer provides the largest content of the magnetization current, the largest angular error and also the largest content of the second harmonic component in the secondary short-circuit current.

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