• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.280-281
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• 2011

Special Protection Scheme(SPS) that operates scenarios about faults beyond the normally protective action is wide system protection technology for the purpose of wide areas protection. Therefore, the SPS focuses on the improvement of the power supply capability by protecting the system rather than protecting the system equipments. Since the SPS requires emergency operation, the operation schedule is set up in advance by analyzing various scenarios. Since the SPS's action scheme uses generator tripping and is a classical method it is presently the most powerful one. However, as the setting of SPS is set to the most severe disturbance, the scheme tends to trip more generators than required to prevent fault propagation. It is highly likely that tripping generator units to prevent fault propagation would result in difficulty of system management and possibility of load shedding. Accordingly, it is desirable that generators are connected to the system within the range that ensures system stability and intelligent SPS is currently under development to solve the problem being stated. In this paper, as a part of developing the intelligent SPS, application of the fast-valving and braking resistor scheme to the generators is being proposed and analysed to reduce the number of tripped generators.

• KIEE International Transactions on Power Engineering
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• v.5A no.2
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• pp.132-137
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• 2005

In Korea, the protection systems against the instability of the nation's power system are insufficient in contrast with many other countries. In addition, there have just been studies carried out on detecting power system instability, while only a few studies pertaining to protection plans against instability exist. This paper focuses on systems to protect against the instability phenomena in the Korean power system. In this paper, we survey possible contingencies in the Korean power system and suggest outline and specs of the SPS (System Protection Scheme) against faults on the 765 kV line, based on simulations. It is concluded that event-based SPS for transient stability is appropriate for the Korean power system. In the simulations, the most severe contingency on the Korean power system is the fault on 765 kV transmission lines. If one of these lines is tripped by a fault, synchronism may be lost on the power plants near this line because of heavy power flow carried by them. In addition, undervoltage in the Metropolitan region is a serious problem in this case since this region receives about half its total power flow through these lines. In order to prevent a synchronism loss, some power plants have to be rejected according to the situations in the simulations.

• Journal of Electrical Engineering and Technology
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• v.4 no.4
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• pp.476-484
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• 2009

This paper deals with improvements to the special protection schemes (SPS) which have been applied to the low probability and high impact contingencies in the Korea Electric Power Corporation (KEPCO) system since 2004. Among them, the SPS for voltage instability in the Seoul metropolitan area is considered in this paper, and is a form of event-based undervoltage load shedding with a single-step scheme. Simulation results based upon a recent event that occurred on 765kV lines show that the current setting values of the SPS have to be revised and enhanced. In addition, by applying response-based multi-step undervoltage load shedding (UVLS) schemes to severe contingencies in the system, more effective results than those of the existing single-step SPS can be obtained. Centralized and distributed UVLS schemes are considered in the simulation. ULTC-based load recovery models and over excitation limiters (OXL) for the KEPCO system are also included in the long-term voltage instability studies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.1
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• pp.411-417
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• 2014

Special Protection Scheme(SPS) for generator tripping action is an emergency control tool that secures the power system stability by instantly tripping the pre-determined number of generators to avoid the acceleration of the remaining generators in a large-scaled power plants when a fault occurs on the drawing transmission lines. However, since the existing operating conditions of SPS are set based on a peak demand, SPS could trip more generators than required if it is activated during the off-peak demand period. For this, this paper proposes the algorithm for setting the operating conditions of SPS through the online stability evaluation with the periodically updated operating conditions of power systems. The proposed algorithm adopts COA for the accuracy and speed of the stability evaluation, and can reduce the number of tripping generators by SPS during the off-peak demand period. This results in reducing the loss of profit caused by a fault on power systems.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.11
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• pp.1554-1560
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• 2017

Prepare a lose of 765kV transmission route in power system operation condition, there are some Special Protection Scheme(SPS)s in Korean power system. These SPS can make some preselected generators are tripped to avoid generator overspeed. Because of many of the new large power plants are installed to existing power generation sites due to the siting problem, the number of generator tripped by SPS should be increased. But that can be a cause of system frequency change under the Under Frequency Relay(UFR) 1st pickup level 59.0Hz. Therefore generation constraint should be considered until new transmission lines are installed. In this paper, we propose the ESS application for generation constraint mitigation by frequency damping control of ESS. To analysis an effect of ESS application, we use PSS/E dynamic simulation tool, CBEST model and controller model. The proposed ESS application is applied to the empirical Korean power system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.6
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• pp.845-851
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• 2015

Load shedding is a last measure to avoid nationwide cascading collapses of power system by removing the pre-determined amount of loads from the main grid. In Korea, SPS(Special Protection System) is prepared to keep the power system stability from the extreme contingency of the critical transmission line losses. Among them, we need to pay attention to 765kV T/L’s because they have great influence on the total system stability. According to the present SPS operating guide, the total loads of 1,500MW should be removed through 2 step under-voltage load shedding(UVLS) scheme in case of 765kV T/L’s contingencies. However, it is not clear to defined how to determine the typical load reduction amounts for each case. This paper proposes a method to estimate appropriate amounts of load shed for 765kV T/L’s contingencies by analyzing the relevant national and international standards.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.10
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• pp.2105-2112
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• 2009

Recently RFID system has been adopted in various fields rapidly. However, we ought to solve the problem of privacy invasion that can be occurred by obtaining information of RFID Tag without any permission for popularization of RFID system To solve the problems, it is Ohkubo et al.'s Hash-Chain Scheme which is the safest method. However, this method has a problem that requesting lots of computing process because of increasing numbers of Tag. Therefore, We suggest the way (process) satisfied with all necessary security of Privacy Protection Shreme and decreased in Tag Identification Time in this paper. First, We'll suggest the SP-Division Algorithm seperating SPs using the Performance Measurement consequence of each node after framing the program to create Hash-Chain Calculated table to get optimized performance because of character of the grid environment comprised of heterogeneous system. If we compare consequence fixed the number of nodes to 4 with a single node, equal partition, and SP partition, when the total number of SPs is 1000, 40%, 49%, when the total number of SPs is 2000, 42%, 51%, when the total number of SPs is 3000, 39%, 49%, and when the total number of SPs is 4000, 46%, 56% is improved.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1049-1056
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• 2010

Recently RFID system has been adopted in various fields rapidly. However, we should solve the problem of privacy invasion that can be occurred by obtaining information of RFID Tag without any permission for popularization of RFID system. To solve these problems, There is the Ohkubo et al.'s Hash-Chain Scheme which is the safest method. However, this method has a problem that requesting lots of computing process because of creasing numbers of Tag. Therefore We, suggest SP-Division algorithm satisfied with all necessary security of Privacy Protection Scheme and decreased in Tag Identification Time in this paper. And this paper implemented it in time standard finding the first key among the data devided into each nodes. The length of Hash-Chain holds 1000, and the total number of SPs increases 1000, 2000, 3000, and 4000. Comparing tag identification time by the total number of SPs and the number of Nodes with single node, extending the number of nodes to 1, 2, 3 and 4, when the number of nodes is 2, 40% of Performance, when the number of nodes is 3, 56%, and when the number of nodes is 4, 71% is improved.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.1
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• pp.81-87
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• 2009

Recently RFID system has been adopted in various fields rapidly. However, we ought to solve the problem of privacy invasion that can be occurred by obtaining information of RFID Tag without any permission for popularization of RFID system To solve the problems, it is Ohkubo et al.'s Hash-Chain Scheme which is the safest method. However, this method has a problem that requesting lots of computing process because of increasing numbers of Tag. Therefore, in this paper we apply the previous method into the grid environment by analyzing Hash-Chain scheme in order to reduce processing time when Tags are identified. We'll implement the process by offering Tag Identification Process Model to divide SPs evenly by node.