scholarly journals Separation of Transformers for Class 1E Systems in Nuclear Power Plants

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Sang-Hyun Lee ◽  
Choong-Koo Chang
Keyword(s):  
Power System ◽  
Electric Power ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Voltage Drop ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Electric Power System ◽  
Improved Model

In order to supply electric power to the safety related loads, safety and reliability of onsite power have to be ensured for the safety function performance in nuclear power plants. Even though the existing electric power system of APR1400 meets the requirements of codes regarding Class 1E system, there is a room for improvement in the design margin against the voltage drop and short circuit current. This paper discusses the amount that the voltage drop and short circuit current occur in the existing electric power system of APR1400. Additionally, this paper studies with regard to the improved model that has the extra margin against the high voltage drop and short circuit current by separation of unit auxiliary transformer (UAT) and standby auxiliary transformer (SAT) for the Class 1E loads. The improved model of the electric power system by separation of UAT and SAT has been suggested through this paper. Additionally, effects of reliability and cost caused by the electric power system modification are considered.

scholarly journals Application of Dynamic Fault Tree Analysis to Prioritize Electric Power Systems in Nuclear Power Plants

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4119
Author(s):  
Sejin Baek ◽  
Gyunyoung Heo
Keyword(s):  
Power Systems ◽  
Power System ◽  
Electric Power ◽  
Dynamic Characteristics ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Electric Power System ◽  
Diesel Generator ◽  
Fault Trees

Because the scope of risk assessments at nuclear power plants (NPPs) is being extended both spatially and temporally, conventional, or static fault trees might not be able to express failure mechanisms, or they could be unnecessarily conservative in their expression. Therefore, realistic assessment techniques are needed to adequately capture accident scenarios. In multi-unit probabilistic safety assessment (PSA), fault trees naturally become more complex as the number of units increases. In particular, when considering a shared facility between units of the electric power system (EPS), static fault trees (SFTs) that prioritize a specific unit are limited in implementing interactions between units. However, dynamic fault trees (DFTs) can be available without this limitation by using dynamic gates. Therefore, this study implements SFTs and DFTs for an EPS of two virtual NPPs and compares their results. In addition, to demonstrate the dynamic characteristics of the shared facilities, a station blackout (SBO), which causes the power system to lose its function, is assumed—especially with an inter-unit shared facility, AAC DG (Alternate AC Diesel Generator). To properly model the dynamic characteristics of the shared EPS in DFTs, a modified dynamic gate and algorithm are introduced, and a Monte Carlo simulation is adopted to quantify the DFT models. Through the analysis of the DFT, it is possible to confirm the actual connection priority of AAC DG according to the situation of units in a site. In addition, it is confirmed that some conservative results presented by the SFT can be evaluated from a more realistic perspective by reflecting this.

Predictive and comparative analysis of NPP modernization with an autonomous hydrogen power complex and gas turbine unit

2021 ◽  
Vol 3 ◽  
pp. 22-30
Author(s):  
Valery Yurin ◽  
Dmitry Bashlykov
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Power System ◽  
Electric Power ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Power Plants ◽  
Thermal Power ◽  
Electric Power System ◽  
Variable Power

Optimizing existing nuclear power plants adding developing power technology can help find effective ways of improving variable power loads in an electric power system. One of the most promising options is combining a nuclear power plant with a newly developed autonomous hydrogen complex reported in our research. The ability of storing unused energy and releasing it when needed will raise contribution of nuclear power plants in compensating improving variable power loads, shorten emissions as well as contribution of conventional thermal power plants into electric power generation. Also, as we demonstrated in our previous research results, a low-power steam turbine plant used in the said autonomous hydrogen complex can support an auxiliary power system of a nuclear power plant reusing residual reactor heat in case of an outage.

Review of Short Circuit Current Prediction Technology in Electric Power System

2021 ◽  
pp. 311-327
Author(s):  
Xiren Miao ◽  
Shengbin Zhuang ◽  
Jiamin Li ◽  
Lingling Tang
Keyword(s):  
Power System ◽  
Electric Power ◽  
Short Circuit ◽  
Short Circuit Current ◽  
Electric Power System

scholarly journals Load Flow Analysis and Short Circuit Faults with the Additional Distributed Generation Wind Turbine 300 kW at Andalas University

2021 ◽  
Vol 1 (1) ◽  
pp. 41-47
Author(s):  
Fadhel Putra Winarta ◽  
Yoli Andi Rozzi
Keyword(s):  
Power System ◽  
Wind Turbine ◽  
Electric Power ◽  
Power Flow ◽  
Voltage Drop ◽  
Short Circuit ◽  
Flow Analysis ◽  
Load Flow ◽  
Electric Power System ◽  
A Value

The study of electric power flow analysis (Load Flow) is intended to obtain information about the flow of power or voltage in an electric power system network. This information is needed to evaluate the performance of the power system. Electrical power flow problems include calculating the flow and system voltage at certain terminals or buses. The benefits of this power flow study are to find out the voltage at each node in the system, to find out whether all the equipment meets the specified limits to deliver the desired power, and to obtain the original conditions in the new system planning. This study is divided into two: the analysis of data when the conditions have not been added wind turbine and after the addition of 300 kW wind turbine with software power station ETAP software 12.6.0 and the Newton-Raphson method will be used in analyzing the power flow of the electric power system. Based on the results of the tests, it is found that the overall value of losses for power flow before the addition of DG is 0.031 MW and 0.037 Mvar, for the voltage drop with the lowest percentage, namely on bus 10 with a percentage of 96.45 for the 0.4 kV system and the 20 kV system on bus 19 with a percentage of 99.03, the largest% PF load was in lump 1 with 98.64 and the smallest% PF was in lump7 with a value of 84.92. The short circuit data value on the 20 kV bus system at Andalas University before the addition of DG with 3-phase disturbances averaged 13.354 A, 1-phase disturbances averaged 3.521 A, 2-phase disturbances averaged 11.719 A and 2 ground phases of 12.842 A Whereas for the value of power flow after the addition of DG in the form of the wind turbine of 300 kW the overall value of losses is 0.032 MW and 0.042 MvarAR, for the voltage drop with the percentage for voltage drop with the lowest percentage is bus 10 with a percentage of 96.63 for system 0, 4 kV and a 20 kV system on bus 14 with a percentage of 98.1, the largest% PF load is in lump 1 with 98.64 and the smallest% PF is in lump7 with a value of 84.92. The short circuit data value on the 20 kV bus system at Andalas University after the addition of DG with 3 phase disturbances has an average value of 13.354 A, 1 phase disturbance averages 3.523 A, 2 phase disturbances average 11.737 A and 2 phases ground is 12.059 A For the source in this system, after the addition of DG, there was a change in the% PF of the PLN grid, namely 79.53 and the wind turbine -83%.

scholarly journals A Novel Methodology for Adaptive Coordination of Multiple Controllers in Electrical Grids

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1474
Author(s):  
Ruben Tapia-Olvera ◽  
Francisco Beltran-Carbajal ◽  
Antonio Valderrabano-Gonzalez ◽  
Omar Aguilar-Mejia
Keyword(s):  
Power Systems ◽  
Power System ◽  
Electric Power ◽  
Large Scale ◽  
Short Circuit ◽  
Dynamic Performance ◽  
Low Frequency ◽  
Electric Power System ◽  
Design Stage ◽  
Positive Interaction

This proposal is aimed to overcome the problem that arises when diverse regulation devices and controlling strategies are involved in electric power systems regulation design. When new devices are included in electric power system after the topology and regulation goals were defined, a new design stage is generally needed to obtain the desired outputs. Moreover, if the initial design is based on a linearized model around an equilibrium point, the new conditions might degrade the whole performance of the system. Our proposal demonstrates that the power system performance can be guaranteed with one design stage when an adequate adaptive scheme is updating some critic controllers’ gains. For large-scale power systems, this feature is illustrated with the use of time domain simulations, showing the dynamic behavior of the significant variables. The transient response is enhanced in terms of maximum overshoot and settling time. This is demonstrated using the deviation between the behavior of some important variables with StatCom, but without or with PSS. A B-Spline neural networks algorithm is used to define the best controllers’ gains to efficiently attenuate low frequency oscillations when a short circuit event is presented. This strategy avoids the parameters and power system model dependency; only a dataset of typical variable measurements is required to achieve the expected behavior. The inclusion of PSS and StatCom with positive interaction, enhances the dynamic performance of the system while illustrating the ability of the strategy in adding different controllers in only one design stage.

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