Damping Analysis of Subsynchronous Oscillation Caused by HVDC

2013 ◽  
Vol 732-733 ◽  
pp. 1065-1068
Author(s):  
Shi Wu Xiao ◽  
Lan Lan Shu
Keyword(s):  
Time Domain ◽  
Test Signal ◽  
Subsynchronous Oscillation ◽  
High Voltage Direct Current ◽  
Damping Characteristics ◽  
Torque Coefficient ◽  
Machine Systems ◽  
Electrical Damping ◽  
The Time Domain ◽  
Signal Method

High Voltage Direct Current transmission (HVDC) will cause torsional interaction under certain conditions. Among a variety of factors, improper rectifier control has fateful effect. In the paper, the test signal method which is the time-domain form of the complex torque coefficient approach (CTC approach) is studied. Its application conditions in multi-machine systems are summarized. Using the test signal method, impacts of DC power, DC voltage, rectifier controller parameters and generator output on electrical damping characteristics in the Suizhong system are studied based on time-domain simulation model.

The Comparative Analysis of SVC and STATCOM on Subsynchronous Oscillation Mitigation

2013 ◽  
Vol 756-759 ◽  
pp. 245-249 ◽  
Author(s):  
Jian Zhang ◽  
Xiang Ning Xiao ◽  
Ben Feng Gao ◽  
Chao Luo
Keyword(s):  
Short Circuit ◽  
Time Domain Simulation ◽  
Subsynchronous Oscillation ◽  
Damping Coefficients ◽  
Torque Coefficient ◽  
Electrical Damping ◽  
The Time Domain ◽  
Generator Terminal ◽  
Short Circuit Fault ◽  
Signal Method

The methods for subsynchronous oscillation mitigation based on SVC and STATCOM are analyzed in this paper. According to the IEEE first benchmark model, the electrical damping coefficients respectively provided by SVC and STATCOM connected at the generator terminal, as well as positive damping condition, are deduced by complex torque coefficient approach. Correlative factors which influence the two positive dampings are compared. The analysis results indicate that the positive damping provided by SVC is proportional to the size of system voltage. The positive damping provided by STATCOM is not affected by the size of system voltage, which is mostly proportional to the subsynchronous voltage produced itself. The controllers of SVC and STATCOM are designed and the positive dampings separately offered by SVC and STATCOM are optimized by phase compensation with test signal method. The time domain simulation reveals that STATCOM has stronger damping ability than SVC in the case of short circuit fault.

Damping Characteristics Analysis Based on Complex Torque Coefficient Method in Sub-Synchronous Oscillations

2014 ◽  
Vol 971-973 ◽  
pp. 988-991
Author(s):  
Han Chen ◽  
Chun Lin Guo
Keyword(s):  
Large Scale ◽  
Power Transmission ◽  
Test Method ◽  
Long Distance ◽  
Damping Characteristics ◽  
Torque Coefficient ◽  
Synchronous Oscillations ◽  
Electrical Damping ◽  
The Time Domain ◽  
Coefficient Method

Because of China's energy and load imbalance, large-scale long-distance power transmission becomes inevitable. Under this background , series compensation capacitor in the power system and HVDC developed rapidly, and the SSO (Sub-synchronous oscillations) caused by HVDC is becoming increasingly apparent. Fundamental reason of SSO lies in the sub-synchronous system negative damping characteristics, so it is necessary to analyze the system damping characteristics. The net system damping includes mechanical and electrical damping. Based on small-signal test method-complex torque coefficient method in the time-domain simulation , paper analyzed the system electrical damping and mechanical damping characteristics.

Sub-Synchronous Oscillation Caused by HVDC and the Damping Characteristic Analysis

2014 ◽  
Vol 971-973 ◽  
pp. 1353-1356
Author(s):  
Han Chen ◽  
Chun Lin Guo ◽  
Qin Lei Chen
Keyword(s):  
Large Scale ◽  
Power Transmission ◽  
Test Method ◽  
Characteristic Analysis ◽  
Long Distance ◽  
Damping Characteristics ◽  
Torque Coefficient ◽  
Electrical Damping ◽  
The Time Domain ◽  
The Impact

Because of China's energy and load imbalance, respectively, large-scale long-distance power transmission becomes inevitable. Under this background , HVDC develops rapidly, SSO (Sub-synchronous oscillations) caused by HVDC is becoming increasingly apparent. The sub-synchronous electrical damping within the frequency range is difficult to calculate. Based on small-signal test method-complex torque coefficient method in the time-domain simulation , the paper calculated the sub-synchronous electrical damping characteristics of the system and analyzed the impact of the unit interaction, DC power and the generator output on sub-synchronous electrical damping characteristics.

Active Power Measurements - An Overview and a Comparison of DSP Algorithms by Noncoherent Sampling

2011 ◽  
Vol 18 (2) ◽  
pp. 173-184 ◽  
Author(s):  
Milos Sedlacek ◽  
Zdenek Stoudek
Keyword(s):  
Time Domain ◽  
Additive Noise ◽  
Digital Signal ◽  
Power Estimation ◽  
Active Power ◽  
Test Signal ◽  
Additional Information ◽  
Measurement Results ◽  
The Time Domain ◽  
Power Measurements

Active Power Measurements - An Overview and a Comparison of DSP Algorithms by Noncoherent Sampling This paper presents an overview of algorithms for one-phase active power estimation using digital signal processing in the time domain and in the frequency domain, and compares the properties of these algorithms for a sinusoidal test signal. The comparison involves not only algorithms that have already been published, but also a new algorithm. Additional information concerning some known algorithms is also included. We present the results of computer simulations in MATLAB and measurement results gained by means of computer plug-in boards, both multiplexed and using simultaneous signal sampling. The use of new cosine windows with a recently published iterative algorithm is also included, and the influence of additive noise in the test signal is evaluated.

Research about Subsynchronous Oscillation Caused by High-Voltage-Direct-Current

2013 ◽  
Vol 805-806 ◽  
pp. 920-925
Author(s):  
Nan Zhou ◽  
Guan Rong Wang
Keyword(s):  
Subsynchronous Oscillation ◽  
Hvdc System ◽  
High Voltage Direct Current ◽  
Turbine Generators ◽  
Electrical Instability ◽  
Electrical Damping ◽  
Oscillation Frequencies ◽  
Damping Torque ◽  
System Frequency ◽  
Shaft Failure

Torsional interaction exists between HVDC converters and turbine-generators, and negative electrical damping provided by HVDC may cause subsynchronous oscillation (SSO) that can lead to turbine-generator shaft failure and electrical instability at oscillation frequencies lower than the fundamental system frequency. This paper makes a preliminary inquiry about the subsynchronous oscillation mechanism caused by the HVDC system, and puts forward Subsynchronous Damping Controller, and eventually makes a damping synchronous oscillation of the electrical Damping torque increment out of the generator electromagnetic torque to suppressing SSO.

Apodisation in the time domain

1992 ◽  
Vol 2 (4) ◽  
pp. 615-620
Author(s):  
G. W. Series
Keyword(s):  
Time Domain ◽  
The Time Domain

JOINT INTERPRETATION OF AIRBORNE ELECTROMAGNETIC DATA IN THE TIME DOMAIN AND FREQUENCY DOMAIN

2018 ◽  
Vol 12 (7-8) ◽  
pp. 76-83
Author(s):  
E. V. KARSHAKOV ◽  
J. MOILANEN
Keyword(s):  
Fourier Transform ◽  
Frequency Domain ◽  
Time Domain ◽  
Frequency Interval ◽  
Single Spectrum ◽  
Simultaneous Inversion ◽  
Homogeneous Half Space ◽  
Time Domain Data ◽  
The Time Domain

Тhe advantage of combine processing of frequency domain and time domain data provided by the EQUATOR system is discussed. The heliborne complex has a towed transmitter, and, raised above it on the same cable a towed receiver. The excitation signal contains both pulsed and harmonic components. In fact, there are two independent transmitters operate in the system: one of them is a normal pulsed domain transmitter, with a half-sinusoidal pulse and a small "cut" on the falling edge, and the other one is a classical frequency domain transmitter at several specially selected frequencies. The received signal is first processed to a direct Fourier transform with high Q-factor detection at all significant frequencies. After that, in the spectral region, operations of converting the spectra of two sounding signals to a single spectrum of an ideal transmitter are performed. Than we do an inverse Fourier transform and return to the time domain. The detection of spectral components is done at a frequency band of several Hz, the receiver has the ability to perfectly suppress all sorts of extra-band noise. The detection bandwidth is several dozen times less the frequency interval between the harmonics, it turns out thatto achieve the same measurement quality of ground response without using out-of-band suppression you need several dozen times higher moment of airborne transmitting system. The data obtained from the model of a homogeneous half-space, a two-layered model, and a model of a horizontally layered medium is considered. A time-domain data makes it easier to detect a conductor in a relative insulator at greater depths. The data in the frequency domain gives more detailed information about subsurface. These conclusions are illustrated by the example of processing the survey data of the Republic of Rwanda in 2017. The simultaneous inversion of data in frequency domain and time domain can significantly improve the quality of interpretation.

scholarly journals Broadband spectroscopy of astrophysical ice analogues

2019 ◽  
Vol 629 ◽  
pp. A112 ◽  
Author(s):  
B. M. Giuliano ◽  
A. A. Gavdush ◽  
B. Müller ◽  
K. I. Zaytsev ◽  
T. Grassi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Optical Properties ◽  
Time Domain ◽  
Complex Refractive Index ◽  
Far Infrared ◽  
Infrared Region ◽  
Thz Radiation ◽  
The Real ◽  
Thz Range ◽  
The Time Domain

Context. Reliable, directly measured optical properties of astrophysical ice analogues in the infrared and terahertz (THz) range are missing from the literature. These parameters are of great importance to model the dust continuum radiative transfer in dense and cold regions, where thick ice mantles are present, and are necessary for the interpretation of future observations planned in the far-infrared region. Aims. Coherent THz radiation allows for direct measurement of the complex dielectric function (refractive index) of astrophysically relevant ice species in the THz range. Methods. We recorded the time-domain waveforms and the frequency-domain spectra of reference samples of CO ice, deposited at a temperature of 28.5 K and annealed to 33 K at different thicknesses. We developed a new algorithm to reconstruct the real and imaginary parts of the refractive index from the time-domain THz data. Results. The complex refractive index in the wavelength range 1 mm–150 μm (0.3–2.0 THz) was determined for the studied ice samples, and this index was compared with available data found in the literature. Conclusions. The developed algorithm of reconstructing the real and imaginary parts of the refractive index from the time-domain THz data enables us, for the first time, to determine the optical properties of astrophysical ice analogues without using the Kramers–Kronig relations. The obtained data provide a benchmark to interpret the observational data from current ground-based facilities as well as future space telescope missions, and we used these data to estimate the opacities of the dust grains in presence of CO ice mantles.

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