Substation power-transformer-loading analysis and computer simulations of loadability under realistic operating conditions

1994 ◽  
Vol 141 (5) ◽  
pp. 413 ◽  
Author(s):  
C.C. Wong
Keyword(s):  
Computer Simulations ◽  
Power Transformer ◽  
Operating Conditions ◽  
Loading Analysis

scholarly journals Analysis of Operating Modes of Oil-Immersed Power Transformers with a Voltage of 10 (6) / 0.4 kV

2021 ◽  
Vol 24 (4) ◽  
pp. 80-91
Author(s):  
A.E. Fokeev ◽  
I.N. Tumakov
Keyword(s):  
Ambient Temperature ◽  
Thermal Aging ◽  
Power Transformer ◽  
Spectral Composition ◽  
Operating Conditions ◽  
Power Transformers ◽  
Load Factor ◽  
Calculation Algorithm ◽  
Load Current ◽  
Aging Rate

The rate of thermal aging of the power transformers windings insulation depends on the effects of the electric field, mechanical stresses, temperature and processes that cause changes in these factors. A calculation algorithm is considered that allows determining the temperature of the most heated point of the windings of an oil power transformer at known values of the load current and ambient temperature. Calculation of the most heated winding point temperature and the rate of thermal aging of insulation for an oil power transformer at different ambient temperatures during the year, different values and different spectral composition of the electric load current showed that in some cases it is possible to violate the permissible operating conditions of power transformers. According to the calculation results, the dependences of the thermal aging rate of insulation on the ambient temperature are constructed, with different load parameters and different load coefficients of power transformers. For the considered modes, in the warm season, the value of the thermal aging rate of insulation significantly exceeds the nominal value. Based on mathematical models of oil power transformers with natural and forced oil circulation, expressions are obtained for determining the coefficient of reduction of the oil power transformers permissible load when the ambient temperature exceeds the normal value of 20 °C. On the basis of these expressions, for practical use, the dependences of the coefficient of reduction of the permissible load on the ambient temperature are constructed. The influence of ambient temperature must be taken into account when choosing the power of oil power transformers, for which it is assumed to operate in full redundancy mode or high load factor values (³ 0.8) in normal mode. To ensure the normative service life of the insulation of the windings, it is necessary to determine the design power of oil power transformers using the coefficient of reduction of the permissible load under the influence of higher harmonics of the current and the coefficient of reduction of the permissible load under the influence of ambient temperature.

An Innovative Solution for Type Testing of Power Transformers

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Manohar Singh ◽  
Vishnuvarddhan Telukanta ◽  
K S Meera
Keyword(s):  
Power Transformer ◽  
Short Circuit ◽  
Operating Conditions ◽  
Power Transformers ◽  
Test Facility ◽  
Online Testing ◽  
Testing Laboratory ◽  
Power Testing ◽  
Grid Operation ◽  
The Impact

Abstract Type tests are essential to assess the short circuit withstand capabilities of transformer windings. The mechanical durability of power equipment are checked against the mechanical forces developed during making/breaking short circuit operations. These type tests are generally carried out in indoor transformer test laboratories. Testing of Power Transformer for size more than 200 MVA in 765/400 kV voltage class in an indoor laboratory is not economically feasible. Now a days, power transformer manufacturers are fabricating single phase auto- power transformers of size up to 630 megawatt volt ampere (MVA) rating. Type testing of these transformers in indoor laboratories is not feasible. In view of this, strong short circuit fault feeding capabilities of the national grids can be utilized for type testing of these power transformers in an online manner. However, this may affect the grid operation/control during weak grid operating conditions. Recently, National High Power Testing Laboratory is established for testing of power transformer upto of 630 MVA. This is a unique online transformer test facility for testing of 765/400/220/132 kV class power transformers. An offline simulation has been carried out in this article, to assess the impact of online type testing on the Indian National grid. In this article, an online testing scheme has been presented which enables the national grid operator to analysis the prevailing grid condition & subsequently to decide the safe rating of the power transformer for online testing. The simulated results are cross checked with field results and it is found that simulated results are close to actual field results. The concurrence of simulated and field results helped in successfully commissioning of the testing laboratory.

Validation of the Combustion Space Simulation of a Glass Furnace Model

2001 ◽  
Author(s):  
B. Golchert ◽  
S. L. Chang ◽  
M. Petrick ◽  
C. Q. Zhou
Keyword(s):  
Heat Transfer ◽  
Computer Simulations ◽  
Glass Furnace ◽  
Validation Studies ◽  
Radiative Heat ◽  
Operating Conditions ◽  
Department Of Energy ◽  
Gas Temperature ◽  
Gas Velocity ◽  
Actual Operating

Abstract A completely coupled glass furnace simulation that combines calculations for the combustion space, glass melt, and radiative heat transfer throughout the furnace has been developed as part of a Department of Energy sponsored program. A major component of this program entailed the collection of an extensive set of data from an operating glass furnace for the purpose of validation. The data collected were compared with the results from computer simulations of the furnace based on the actual operating conditions. These comparisons indicated that the computated results were valid. This paper will present and discuss the gas velocity and gas temperature measurements/validation studies.

scholarly journals Power Transformer Spatial Acoustic Radiation Characteristics Analysis under Multiple Operating Conditions

Energies ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 74 ◽  
Author(s):  
Liming Ying ◽  
Donghui Wang ◽  
Jinwei Wang ◽  
Guodong Wang ◽  
Xiaowen Wu ◽  
...  
Keyword(s):  
Acoustic Radiation ◽  
Power Transformer ◽  
Operating Conditions ◽  
Radiation Characteristics ◽  
Characteristics Analysis

scholarly journals Succor System and Failure Indication for the Starter Batteries of Emergency Gensets

2020 ◽  
Vol 64 (4) ◽  
pp. 412-421 ◽  
Author(s):  
Annunziata D'Orazio ◽  
Stefano Elia ◽  
Ezio Santini ◽  
Manuel Tobia
Keyword(s):  
Dynamic Model ◽  
Computer Simulations ◽  
Automatic System ◽  
Operating Conditions ◽  
Timely Manner ◽  
Simulink Model ◽  
The Subject ◽  
Start Ups ◽  
Human Losses

Nowadays there are 3 % of missed start-ups of emergency gensets in Italian hospitals every year. The subject of this work is the analysis of the failure to start an emergency genset due to the failure of the batteries. The work is based on ten years statistics of maintenance on hospital facilities. A real case study is here described; measurements were made on a 1000 kVA genset of a hospital to study the real operating conditions of the system. The whole electrical, mechanical and dynamic model of the starter system of a genset is studied. Computer simulations for this study are based on the Matlab/Simulink model of the considered starter system. An automatic system of parallel between the batteries of different generators is presented as a solution to the problem. This system can also indicate to the maintenance technician the need to replace a partially deteriorated battery in a timely manner. It is also proved that it is possible to succor the failed battery instantly without losing the first part of the starting transient. The work demonstrates that the failure to start, due to a fault in the batteries, can be significantly reduced by using the proposed solution. With this technical proposal the risk of blackouts and relative human losses are largely reduced.

scholarly journals Power Transformer Voiceprint Operation State Monitoring Considering Sample Unbalance

2021 ◽  
Vol 2137 (1) ◽  
pp. 012007
Author(s):  
shoulong Chen ◽  
Ping He ◽  
HongHua Xu ◽  
LaiBin Yin ◽  
LingYan Wang ◽  
...  
Keyword(s):  
Feature Vector ◽  
Recognition Accuracy ◽  
Power Transformer ◽  
Frequency Multiplier ◽  
Operating Conditions ◽  
Utilization Rate ◽  
Signal Acquisition ◽  
State Monitoring ◽  
Light Load ◽  
Component Amplitude

Abstract The voiceprint characteristics of transformers are closely related to the operating conditions, but there is currently a lack of effective research on the voiceprint characteristics of transformers during operation. First of all, this article collects three operating conditions of load, light load, and no load on the basis of the transformer voiceprint signal acquisition platform. Secondly, in view of the characteristics of the transformer’s voiceprint, the 50Hz frequency multiplier component amplitude is extracted to form a feature vector, which solves the problem of low utilization rate of common feature extraction information. Finally, in view of the problem of transformer voiceprint failure and sample imbalance caused by fewer abnormal samples, a pattern recognition based on the RUSBoost algorithm is proposed. The algorithm has good recognition accuracy and applicability for transformer voiceprint samples with imbalance problems. The research results provide effective support for the monitoring and identification of the mechanical condition of transformers with sample unbalanced voiceprints, and the analysis of the operating conditions can effectively eliminate the errors that may be caused by their own different operating conditions.

scholarly journals Development of a power transformer model for high-frequency transient phenomena

2021 ◽  
Vol 19 ◽  
pp. 217-221
Author(s):  
L. Braña ◽  
◽  
A. Costa ◽  
R. Lopes
Keyword(s):  
Transmission Lines ◽  
Power Transformer ◽  
Renewable Energy Sources ◽  
Electrical Energy ◽  
Energy System ◽  
Operating Conditions ◽  
Critical Element ◽  
Electrical Networks ◽  
Transient Phenomena ◽  
Transformer Model

In recent years, the proliferation of distributed renewable energy sources and the application of new rules for the exploitation of electrical networks imposed by the markets have dictated increasingly demanding operating conditions for electric power transformers, creating new challenges in their exploration and conservation. Transformers that, in addition to the transmission lines, are certainly the most important and critical element of any electrical energy system. Adequate models are necessary to accurately describe transformer behavior and internal response when submitted to different external requests imposed by the network, particularly during transient phenomena, as well as, to properly assess system vulnerabilities and network optimization. This effort is being carried out today by several research groups in the world, namely from Cigré and IEEE. In this work, a transformer model to be integrated into a timedomain equivalent circuit is developed and discussed. Results obtained with this model are compared with measurements obtained by the Cigré JWG A2/C4.52 in a power transformer used as a reference for the working group.

Experimental study of vibration characteristics of 110 kV oil-immersed transformer

2020 ◽  
pp. 095745652094827
Author(s):  
Xiang Li ◽  
Juan Mo ◽  
Yuchao Ma ◽  
Ling Lu
Keyword(s):  
Large Scale ◽  
Power Transformer ◽  
Short Circuit ◽  
Vibration Characteristics ◽  
Operating Conditions ◽  
Theoretical Research ◽  
Voltage Level ◽  
Reduction Methods ◽  
Frequency Components ◽  
Short Circuit Currents

As the voltage level and capacity of power transformer continue to rise, this results in its increasingly prominent vibration and noise problems. In this article, we study the vibration characteristics of the 110-kV oil-immersed transformer by means of experiments. Under different no-load voltages and short-circuit currents, the vibration signals in different positions and directions of the transformer are monitored respectively, and the vibration laws are analyzed. First, the vibration law of transformers is closely related to the operating conditions of transformers, which directly affects the frequency components of transformer vibration and the amplitude corresponding to different frequencies; second, it is found that the vibration law of transformers facing different directions will change under different operating conditions; and third, it summarizes the vibration of transformers in different positions under different operating conditions. These results can not only be used as the experimental basis for the theoretical research on large-scale transformer noise but also provides experimental support for the research on vibration reduction and noise reduction methods of large-scale transformer in engineering.

Review of Computer Simulations of Regenerative Heat Exchangers

1978 ◽  
Vol 11 (8) ◽  
pp. 309-312
Author(s):  
A. J. Willmott
Keyword(s):  
Heat Exchanger ◽  
Recent Work ◽  
Computer Simulations ◽  
Heat Exchangers ◽  
Operating Conditions ◽  
Design Criteria ◽  
Regenerative Heat ◽  
Regenerative Heat Exchanger ◽  
Fuel Savings

Early models of the stationary performance of the regenerative heat exchanger are discussed together with more recent work in which the behaviour under chronologically varying operating conditions is simulated. The need is presented for better control facilities and possibly new design criteria if fuel savings in regenerative heat exchanger non-stationary operations are to be effected.

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