• Journal of Electrical Engineering and Technology
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• v.4 no.4
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• pp.492-498
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• 2009

The placement of the UPFC is the major concern to ensure the full potential of utilization in the transmission network. Voltage stability enhancement with the optimal placement of UPFC using stability index such as modal analysis, Voltage Phasor method is made and the loss minimization including UPFC is formulated as an optimization problem. This paper proposes particle swarm optimization for the exact real power loss minimization including UPFC. The implementation of loss minimization for the optimal location of UPFC was tested with IEEE-14 and IEEE-57 bus system.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.1
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• pp.6-12
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• 2000

This paper presents various processes of dynamic voltage collapse which is initiated by various power system disturbances, and the impacts of dynamic voltage controllers. According to the analysis results, the composition of induction motors with short time constants affects the voltage collapse strongly. Also, it is proved that the addition of fast acting reactive compensation devices, such as SVC, at high reactive loss sensitivity($$\delta$$Q$$_luss/\delta$$P$$_L$$) buses could be one of the best countermeasure to escape the voltage collapse.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.483-485
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• 2005

In 2003, there was a wide-area blackout in the United States and Canada. More than fifty million people underwent power failure and the estimated financial loss was about four billion dollars. By such wide-area blackouts, the interest in voltage stability has increased gradually. In order to maintain the voltage stability, the preventive control is essential for a contingency. In this paper, a proper preventive control is determined for defined severe contingencies. Among the preventive control methods (generation rescheduling, load curtailment, tap adjusting, injecting the shunt capacitor, and so on.), this paper presents the injection of shunt capacitors by the sensitivity analysis of the voltage stability assessment for preventive controls. The 2006-2010 KEPCO summer peak system is used in case studies.

• Nuclear Engineering and Technology
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• v.52 no.12
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• pp.2821-2835
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• 2020

The phenomenon identification and ranking table (PIRT) is an important basis in the nuclear power plant (NPP) thermal-hydraulic analysis. This study focuses on the importance ranking of the input parameters when lacking the PIRT, and the target scenario is the small break loss of coolant accident (SBLOCA) in a pressurized water reactor (PWR) CPR1000. A total of 54 input parameters which might have influence on the figure of merit (FOM) were identified, and the sensitivity measure of each input on the FOM was calculated through an optimized moment-independent global sensitivity analysis method. The importance ranking orders of the parameters were transformed into the Savage scores, and the parameters were categorized based on the Savage scores. A parameter importance ranking table for the SBLOCA scenario of the CPR1000 reactor was obtained, and the influences of some important parameters at different break sizes and different accident stages were analyzed.

• Journal of Power Electronics
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• v.11 no.1
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• pp.90-96
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• 2011

Congestion management is one of the most challenging aspects in the recently deregulated electricity markets. FACTS devices have been shown to be an efficient alternative to control the flow of power in lines, resulting in increased loadability, lower system loss and a reduced cost of production. In this paper, the application of a static series synchronous compensator (SSSC) for the purpose of congestion management of power systems has been studied. A sensitivity-based analysis method is utilized for effective determination of the SSSC location in an electricity market. The method is topology based and it is independent of the system operation point. A power injection p-model is developed for the SSSC in this study. Numerical results based on the modified IEEE 14 bus system with/without the SSSC demonstrate the feasibility as well as the effectiveness of the SSSC for congestion management in a network. The results obtained when using the SSSC to improve system transfer capability and congestion management is encouraging.

• The KSFM Journal of Fluid Machinery
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• v.15 no.6
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• pp.39-45
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• 2012

This paper describes the outcome of the design of a 200 kW class micro gas turbine and the sensitivity of its performance (efficiency and power) to the variations in major design parameters. The reference design parameters were set up based on the best available component technologies. The resulting net electricity generation efficiency of the micro gas turbine package was found to be competitive to those of other systems in the market. The sensitivities of power and efficiency to the variations in compressor and turbine efficiencies, pressure ratio, turbine inlet temperature, recuperator effectiveness, secondary air ratio, pressure loss ratios of both the cold and hot sides of the recuperator were estimated. Based on the sensitivity data, a simplified method to predict the variation in system performance responding to the combinations of small changes in all design parameters were set up and validated.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.66-68
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• 2000

The Eigen analysis in large power system provides much useful information that is not got in nose curve. The branch participation factor is not quantitative information and is an indirect method calculating incremental change in branch reactive loss. But the Eigen sensitivity analysis to each mode is direct and provides of quantitative information but this method because of needing much time is used in large power system. In this paper the Hessenberg method is used to obtaining dominant eignvalues and corresponding eigenvectors of Jacobian matrix. Ranking the critical contingencies is done by computing the Eigen sensitivity of each dominant eignvalues for changes of each line. The proposed algorithm is tested on the New England 30-bus system and KEPCO system in the year of 2000, which comprises of 791-bus and 2500-branches.

• ETRI Journal
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• v.6 no.4
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• pp.31-36
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• 1984

This paper presents an efficient method for real power loss minimization and for improvements in voltage profiles. This method is accomplished by optimal control of reactive power in the system. The problem is formulated as an optimization problem, suitable for solution by linear programming technique. After establishing the objective function for minimizing the system losses with the help of linearised sensitivity relationships of control variables, i. e., the transformer tap position, generator terminal voltages and switchable reactive power sources. The linear programming technique is used to determine the optimal adjustments to the above variables, simultaneously satisfying the constraints. The proposed algorithm has been tested on a sample system and the result is presented and discussed.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1261-1268
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• 2013

This study proposes a voltage and reactive coordinative control strategy with distributed generator (DG) in a distribution power system. The aim is to determine the optimum dispatch schedules for an on-load tap changer (OLTC), distributed generator settings and all shunt capacitor switching on the load and DG generation profile in a day. The proposed method minimizes the real power losses and improves the voltage profile using squared deviations of bus voltages. The results indicate that the proposed method reduces the real losses and voltage fluctuations and improve receiving power factor. This paper proposes coordinated voltage and reactive power control methods that adjust optimal control values of capacitor banks, OLTC, and the AVR of DGs by using a voltage sensitivity factor (VSF) and dynamic programming (DP) with branch-and-bound (B&B) method. To avoid the computational burden, we try to limit the possible states to 24 stages by using a flexible searching space at each stage. Finally, we will show the effectiveness of the proposed method by using operational cost of real power losses and voltage deviation factor as evaluation index for a whole day in a power system with distributed generators.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.6
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• pp.579-589
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• 1989

In this paper, planar power dividers/combiners for millimeter waves K-band or bands which can be printed on the substrates of hybrid or monolithic IC by surface mounting are designed and studied. Power dividers/combiners, and the conductor loss of microstrip lines in particualr the existing Wilkinson power dividers/combiners is modified ad amployes by ist equivalent circuit. Microwave CAD program SUPEROMPACT is employed for the Wilkinson power combiner which is modified and analyzed to reduce the high frequency coupling between the branches of the combiner, and the method to diminish the sensitivity of the input reflection of $2^n$-way power dividers/combiners is studied employing the commerical microwave CAD program package SUPERCOMPACT.