• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.73-76
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• 2001

This paper presents a new systematic contingency selection, screening and ranking method for on-line transient security assessment. Transient stability of a particular generator is influenced most by fault near it. Fault at the transmission lines adjacent to the generators are selected as contingency. Two screening methods are developed using the sensitivity of modal synchronizing torque coefficient and computing an approximate critical clearing time(CCT) without time simulation. The first method, which considers only synchronizing power, may mislead in some cases since it does not consider the acceleration power. The approximate CCT method, which consider both the acceleration and deceleration power, worked well. Finally the Single Machine Equivalent(SIME) method is implemented using IPLAN of PSS/E for detailed stability analysis.

• Journal of Electrical Engineering and Technology
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• 제4권3호
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• pp.353-359
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• 2009

This paper proposes a novel technique for calculating the security costs that properly includes ramping constraints in the operation of a deregulated power system. The ramping process is modeled by a piecewise linear function with certain assumptions. During this process, a ramping cost is incurred if the permissible limits are exceeded. The optimal production costs of the power producers are calculated with the ramping cost included, considering a time horizon with N-1 contingency cases using contingency constrained optimal power flow (CCOPF), which is solved by the primal-dual interior point method (PDIPM). A contingency analysis is also performed taking into account the severity index of transmission line outages and its sensitivity analysis. The results from an illustrative case study based on the IEEE 30-bus system are analyzed. One attractive feature of the proposed approach is that an optimal solution is more realistic than the conventional approach because it satisfies physical constraints, such as the ramping constraint.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.327-329
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• 2001

This paper presents a fast and accurate contingency analysis in EHV systems for line outages, loss of generation of redispatching and loss-of-load or load management. Unlike other contingencies, line outage requires the modification of the Jacobian of the base case power flow and the calculation of its new inverse, which is substantially different from the original inverse. In this paper, we obtain the inverse of the new Jacobian from the original inverse without repeating the time consuming matrix inversion process. Numerical test results show the significant improvement in the accuracies compared with those obtained using the original inverse.

• Journal of Electrical Engineering and Technology
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• 제13권1호
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• pp.105-113
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• 2018

This paper proposes pre-analysis on planning of high-voltage direct current (HVDC) transmission system applied to Korea electric power grid. HVDC transmission system for interface lines has been considered as alternative solution for high-voltage AC transmission line in South Korea since constructing new high-voltage AC transmission lines is challenging due to political, environmental and social acceptance problems. However, the installation of HVDC transmission system as interface line in AC grid must be examined carefully. Thus, this paper suggests three scenarios to examine the influences of the installation of HVDC transmission system in AC grid. The power flow and contingency analyses are carried out for the proposed scenarios. Power reserves in metro area are also evaluated. And then the transient stability analysis focusing on special protection scheme (SPS) operations is analyzed when critical lines, which are HVDC lines or high voltage AC lines, are tripped. The latest generic model of HVDC system is considered for evaluating the impacts of the SPS operations for introducing HVDC system in the AC grid. The analyses of proposed scenarios are evaluated by electromechanical simulation.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 추계학술대회 논문집
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• pp.297-302
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• 2003

This study was carried out to check the contingency planning methods under the analysis of oil spill potential and make a guide line to apply the results to the port of Busan. The expected spilled oil drift patterns are considered with the most probable scenarios under the base of the oil spill potential. The results obtained from this study are as follows: (1) Analysis method of oil spill potent was proposed and the applicability was proved by the application example to the port of Busan to make the contingency plan. (2) Responsible oil spill contingency planning methods / flow are suggested considered environmental factors and the oil spill potential. (3) The coastal waters of Busan was consist of rocky flat, man-made solid shore and beach shore. Marine traffic have high density of oil tanker and cargo ship. Also, oil tanker ship are examined in the small ships to be less than 3000t to supply oil to the ship moored / anchored as well as the large amount of oil tank / basin are located along the coast of Busan port. These systems are introduced to make in put data to the analysis of oil spill potential. (4) According to the analysis of historical records of oil spill accident in Busan, the frequency of accidents by cargo ship rank highest and 45% of accidents is caused by carelessness. about 65% of total accidents shows a small spill accident of less than $10k{\ell}$.

• KIEE International Transactions on Power Engineering
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• 제2A권4호
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• pp.131-135
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• 2002

This paper describes a new ultra-fast contingency screening algorithm for on-line TSA without time simulation. All machines are represented in a classical model and the stability index is defined as the ratio between acceleration power during a fault and deceleration power after clearing the fault. Critical clustering of machines is done based on the stability index, and the power-angle curve of the critical machines is drawn assuming that the angles of the critical machines increase uniformly, while those of the non-critical ones remain constant. Finally, the critical clearing time (CCT) is computed using the power-angle curve. The proposed algorithm is tested on the KEPCO system comprised of 900-bus and 230-machines. The CCT values computed with the screening algorithm are in good agreement with those computed using the detailed model and the SIME method. The computation time for screening about 270 contingencies is 17 seconds with 1.2 GHz PC.

• 대한전기학회논문지
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• 제37권5호
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• pp.272-281
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• 1988

The problem of optimal transmission system planning is to find the most economical locations and time of transmission line construction under the various constraints such as available rights-of-way, finances, the technical characteristics of power system, and the reliability criterion of power supply, and so on. In this paper the constraint of right-of-way is represented as a finite set of available rights-of-way. And the constructed for a unit period. The electrical constraints are represented in terms of line overload and steady state stability margin. And the reliability criterion is dealt with the suppression of failure cost and with single-contingency analysis. In general, the transmission planning problem requires integer solutions and its objective function is nonlinear. In this paper the objective function is defined as a sum of the present values of construction cost and the minimum operating cost of power system. The latter is represented as a sum of generation cost and failure cost considering the change of yearly load, economic dispatch, and the line contingency. For the calculation of operating cost linear programming is adopted on the base of DC load flow calculation, and for the optimization of main objective function nonlinear Branch-and-Bound algorithm is used. Finally, for improving the efficiency of B & B algorithm a new sensitivity analysis algorithm is proposed.

• 전기의세계
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• 제26권3호
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• pp.84-91
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• 1977

A modified version of algorithm and computer program is proposed to improve the currently available contingency analysis methode for the security control of power system. The underlying principle is based upon the reasonable modification of the current methods suggested by Stagg, Tinny, Alsac, and Stott in consideration of speed, aceuracy, reliability and convergency characteristics. The algorithm and program are desirgned especially for On-Line operation, although Off-Line applications are readily available. Several case studies on the Koren Power Company's 48-bus, 91-line system have shown that the method proposed is efficiently powerful in a sense of practical applicability.

• 전기학회논문지
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• 제62권8호
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• pp.1053-1058
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• 2013

Because of computational burden and complex topology of substation, a transmission overload relief using circuit-breaker switching was very complex and difficult. However, a on-line algorithm for reducing the overloads in transmission lines has made progress due to the advance of IT technology. This paper describes the methodology for alleviating the overloads in transmission lines by circuit-breaker switching. First, the severe contingency lists and substations were selected from the results of contingency analysis. Then the switch combinations are determined using circuit-breakers of the selected substation. The topology changes are limited to equipment outage, bus split, island split, bus merge and island merge. Finally, the fast screening and full analysis methods are used to analyze the overload in transmission lines. To verify the performance of the proposed methodology, we performed a comprehensive test for both test system and large-scale power systems. The results of these tests showed that the proposed methodology can accurately alleviate the overloads in transmission lines from online data and can be applied to on-line applications.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 A
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• pp.201-204
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• 1992

In the conventional load flow technique, it is assumed that the generator at the slack bus is used to supply the transmission losses and the change of power due to the generator outage. The assumption is not true in physical sense. This paper presents a new load flow technique that considers the governor-frequency characteristics and load-frequency characteristics and the technique is consistent with the actual power system phenomenon. This paper proposes an efficient methodology using sensitivity with the new technique for contingency analysis, which is used to calculate the line flows. Computational results of this technique applied to IEEE 14-bus system are presented.