The Identification of an Adequate Stressing Level to Find the Proper Running-In Conditions of a Lubricated DLC-Metal-System

Using a tribometer equipped with a high-resolution wear measurement unit (RNT), the running-in of a diamondlike carbon (DLC) iron spray coating contact was analyzed and optimized. The optimization comprised an initial parameter field with different load and speed levels to find key operation points. These points were used to compose a dedicated running-in parameter field. The analysis underlined the importance of identifying the adequate stressing conditions. With respect to our concept of the running-in corridor, a high-power running-in has to be preferred to obtain a tribological system with low friction, small total wear and wear rate, high system stability, and low sensitivity to external changes.

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Wide Area Input Stabilizer for Damping of Power System Inter-Area Oscillation

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.479-480.530 ◽

2013 ◽

Vol 479-480 ◽

pp. 530-534

Author(s):

Van Dien Doan ◽

Ta Hsiu Tseng ◽

Pei Hwa Huang

Keyword(s):

Power System ◽

System Stability ◽

Measurement Unit ◽

Small Signal Stability ◽

Signal Stability ◽

Power Oscillations ◽

Study Results ◽

System Stabilizer ◽

Small Signal Stability Analysis ◽

Remote Feedback

The main objective of this paper is to report the small signal stability analysis of Vietnam Power System which has a longitudinal network structure with the consideration of power system stabilizer (PSS) in operation to enhance the damping of inter-area oscillation by using local as well as remote feedback signals via phasor measurement unit (PMU). Both methods of frequency domain and time domain analyses are used to investigate the performance of the power system. The study results show that by proper selection of PSS installation locations and remote feedback signals, power oscillations on the tie-line will be reduced and the system stability is thus improved.

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Parameters Identification of Equivalent Model of Permanent Magnet Synchronous Generator (PMSG) Wind Farm Based on Analysis of Trajectory Sensitivity

Energies ◽

10.3390/en13184607 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4607

Author(s):

Jian Zhang ◽

Mingjian Cui ◽

Yigang He

Keyword(s):

Particle Swarm Optimization ◽

Hybrid Algorithm ◽

Wind Farm ◽

Particle Swarm ◽

System Stability ◽

Equivalent Model ◽

Classical Particle ◽

Measurement Unit ◽

Swarm Optimization ◽

Trajectory Sensitivity

As wind farms have great influences on power system stability, it is essential to develop an adaptive as well as robust equivalent model of it. In this paper, a detailed equivalent model of PMSG wind farm and initialization method is developed. The trajectory sensitivity of parameters is analyzed. Then, the key parameters are estimated using improved Genetic Learning Particle Swarm Optimization (GLPSO) hybrid algorithm with phasor measurement unit (PMU). The description and generalization capability, stability for parameter identification of the equivalent model under wake effects, and when some wind turbines are off-line or wind speed is unknown after an event are analyzed. The maximum differences between the values of estimated parameters and their real ones are less than 10% for the proportional magnification constant of DC voltage controller Kp2 and grid side current controller Kp3. The convergence rate and global optimization performance of the improved GLPSO hybrid algorithm is 0.5 times higher than the classical particle swarm optimization algorithm (PSO) and genetic algorithm (GA).

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An Investigation into the Application of Digital Prediction Filters to Direct Digital Control Systems

Measurement and Control ◽

10.1177/002029407400700705 ◽

1974 ◽

Vol 7 (7) ◽

pp. 255-262

Author(s):

P. D. Roberts

Keyword(s):

Digital Control ◽

Digital Simulation ◽

Taylor Series Expansion ◽

System Stability ◽

Process Noise ◽

Digital Control Systems ◽

Low Sensitivity ◽

Accuracy Of Prediction ◽

Prediction Filter ◽

Direct Digital Control

The report describes a digital simulation study of the application of discrete prediction filters, designed from Taylor series expansion or the method of least squares, to direct digital control, where the prediction filter is inserted in the feedback path. The effects on system performance to set-point changes and load disturbances are investigated. In addition, the effects of process noise and system stability are considered. It is concluded that accuracy of prediction is not the most important property which affects control performance. Best performance is obtained using a filter which has a low sensitivity to process noise and predicts as far as possible into the future while remaining within stability constraints.

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Gauss-Seidel Method based Voltage Security Analysis of Distribution System

International Journal of Electrical and Computer Engineering (IJECE) ◽

10.11591/ijece.v8i1.pp43-51 ◽

2018 ◽

Vol 8 (1) ◽

pp. 43

Author(s):

Gagari Deb ◽

Kabir Chakraborty

Keyword(s):

Power System ◽

Distribution System ◽

Critical Line ◽

Security Analysis ◽

System Stability ◽

Measurement Unit ◽

Power Network ◽

Radial Distribution System ◽

Voltage Security ◽

Base Data

Complexity of modern power network and Large disturbance results voltage collapse. So, voltage security analysis is important in power system. Indicators are helpful in voltage stability analysis, as they give information about the state of the system. In this paper a new indicator namely Distribution System Stability Indicator (DSSI) has been formulated using the information of Phasor Measurement Unit (PMU).The proposed indicator (DSSI) is tested on standard IEEE 33 bus radial distribution system. The suggested indicator is also applicable to the equivalent two bus system of a multi-bus power system. The proposed indicator is calculated for different contingent conditions at different system load configurations. The result of DSSI is verified with the standard indicator (VSI) which proves applicability of the proposed indicator. The bus voltages of all the buses at base loading and at maximum loading are evaluated for base data and for tripping of most critical line.

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Fullerene-like hydrogenated carbon films with super-low friction and wear, and low sensitivity to environment

Journal of Physics D Applied Physics ◽

10.1088/0022-3727/43/1/015404 ◽

2009 ◽

Vol 43 (1) ◽

pp. 015404 ◽

Cited By ~ 20

Author(s):

Li Ji ◽

Hongxuan Li ◽

Fei Zhao ◽

Weilong Quan ◽

Jianmin Chen ◽

...

Keyword(s):

Friction And Wear ◽

Carbon Films ◽

Low Friction ◽

Low Sensitivity

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Structure and optical properties of diamondlike carbon synthesized by plasma immersion ion processing

Journal of Materials Research ◽

10.1557/jmr.1999.0280 ◽

1999 ◽

Vol 14 (5) ◽

pp. 2080-2087 ◽

Cited By ~ 7

Author(s):

Xiao-Ming He ◽

D. H. Lee ◽

K. C. Walter ◽

D. Q. Li ◽

M. Nastasi

Keyword(s):

Optical Properties ◽

High Hardness ◽

Optical Transmittance ◽

Low Friction ◽

Substrate Bias Voltage ◽

High Optical Transmittance ◽

Diamondlike Carbon ◽

Optical Gap Energy ◽

Ar Gas ◽

Very High

Hard and transparent diamondlike carbon (DLC) films have been prepared on room-temperature substrates by using a C2H2–Ar plasma immersion ion processing (PIIP) method. The optical properties of the DLC films with different thicknesses deposited on PMMA (polymethyl methacrylate), silicon wafers, and glass plates were systematically examined. It was found that careful control of substrate bias voltage was needed for favorable growth of DLC films with low atomic hydrogen content, high hardness and wear resistance, and excellent optical properties. The resultant DLC films exhibited a low friction coefficient, high optical gap energy, and very high optical transmittance both in infrared and visible light ranges. The study confirmed that C2H2–Ar PIIP with low negative bias voltages and suitable C2H2/Ar gas ratios can produce optically transparent and hard DLC films on optical materials.

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Medium-Voltage Impedance Measurement Unit for Assessing the System Stability of Electric Ships

2018 IEEE Power & Energy Society General Meeting (PESGM) ◽

10.1109/pesgm.2018.8586103 ◽

2018 ◽

Author(s):

Marko Jaksic ◽

Zhiyu Shen ◽

Igor Cvetkovic ◽

Dushan Boroyevich ◽

Rolando Burgos ◽

...

Keyword(s):

Impedance Measurement ◽

System Stability ◽

Measurement Unit ◽

Medium Voltage

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Intraday imbalance optimization: incentives and impact of strategic intraday bidding behavior

Energy Systems ◽

10.1007/s12667-021-00445-9 ◽

2021 ◽

Author(s):

Christopher Koch

Keyword(s):

Portfolio Management ◽

Supply And Demand ◽

Trading Strategies ◽

System Stability ◽

Short Term ◽

Percentage Points ◽

Pricing Rules ◽

Different Types ◽

High System ◽

Intraday Market

AbstractIntraday markets are crucial to balance supply and demand in the very short-term, up to delivery. They are often designed as continuous auctions with a pay-as-bid pricing mechanism. While several studies assess trading strategies to balance different types of portfolios, they normally do not consider the incentives of the imbalance prices for portfolio management. This paper analyzes a strategy of taking positions in the German intraday market based on expected imbalance prices and examines its impact on system stability. Using a logistic regression model, it is possible to accurately predict the direction of the overall system balance and to apply a profitable trading strategy. For a period from 01/07/2017 to 30/06/2019, the strategy outperforms a simple approach by EUR 47 000 per MW. However, this behavior would predominantly not have been system supportive due to biased imbalance price incentives. These are asymmetric price spreads and insufficiently low imbalance prices compared to intraday prices. An efficient intraday price constraint would partly solve the problem. The overall share of system supportive imbalance positions would raise by ten percentage points. In situations with high system wide imbalances, up to three-quarters of the positions would stabilize the system. These findings are important for regulation in Germany and other countries with a single imbalance pricing as they provide an indication for crucial points of the imbalance pricing rules to incite appropriate market behavior.

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THE EFFECT OF WEAR DEBRIS REMOVAL ON THE FRETTING OF ROUGH SURFACES

Tribologia ◽

10.5604/01.3001.0010.5993 ◽

2017 ◽

pp. 47-54 ◽

Cited By ~ 1

Author(s):

Agnieszka LENART ◽

Paweł PAWLUS ◽

Andrzej DZIERWA ◽

Sławomir WOŚ

Keyword(s):

Normal Load ◽

Test Duration ◽

Wear Particles ◽

Tribological System ◽

Total Wear ◽

Debris Removal ◽

42Crmo4 Steel ◽

Rough Milling ◽

Number Of Cycles ◽

Ball On Disc

Experiments were conducted using an Optimol SRV5 ball-on-disc tribotester under dry gross slip fretting conditions. A sphere of 10 mm diameter from 100Cr6 steel of 64 HRC hardness contacted a disc made of 42CrMo4 steel of lower hardness (42 HRC). Normal load was set to 45 N, the test duration was 15 min, the number of cycles was 18000, and the frequency was 20 Hz. Tests were performed at 300C temperature, and displacement amplitude was set to 0.1 mm. Wear of the disc and ball was examined by a white light interferometer Talysurf CCI Lite. Wear particles were removed from a contact zone using blow-by with compressed air of constant pressures of 0.1, 0.3, and 0.5 MPa. Disc samples had different surface topography after polishing, vapour blasting, grinding, rough milling, and finishing milling. Due to debris removal, total wear of the analysed tribological system typically increased. Debris ejection led to a decrease in the wear of discs and an increase in the wear of balls.

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