보이드 기법을 적용한 트리 기반의 안전한 RFID 경계 결정 프로토콜

안해순(Hae-Soon Ahn),윤은준(Eun-Jun Yoon),부기동(Ki-Dong Bu),남인길(In-Gil Nam) 한국정보과학회 2011 정보과학회논문지 : 정보통신 Vol.38 No.3

최근 RFID 시스템에서 근접 인증에 사용되는 비접촉식 스마트카드와 같은 RFID 태그들이 경계 위조(distance fraud) 공격, 마피아 위조(mafia fraud) 공격, 테러리스트 위조(terrorist fraud) 공격과 같은 다양한 위치 기반 공격인 중계 공격(relay attack)들에 매우 취약함이 증명되었다. 이러한 중계 공격들은 리더와 원거리에 있는 합법적인 태그 사이에서 인증 과정이 진행되는 동안에 물리 계층의 신호를 중계함으로써 발생된다. 위와 같은 중계 공격들을 방지하기 위한 해결책으로 리더와 태그 사이의 메시지 송수신 왕복 시간을 측정하는 경계 결정(distance-bounding) 프로토콜에 관한 연구가 활발히 진행되고 있다. 2009년에 Avoine과 Tchamkerten은 2진 트리를 기반으로 인증을 수행하는 AT-RFID 경계 결정 프로토콜을 제안하였다. 그러나 AT-RFID 프로토콜은 공격자에게 ? 번의 왕복에서 75%의 성공 확률을 제공하여 중계 공격을 완벽히 방어할 수 없다. 본 논문에서는 공격자에게 ?번의 왕복에서 각각 67%와 44%의 성공 확률을 제공하는 SEC-RFID와 EFF-RFID 경계 결정 프로토콜을 제안한다. 제안한 프로토콜은 void 기법을 적용한 트리 기반의 안전한 SEC-RFID 경계 결정 프로토콜과 높은 저장 공간 효율성을 제공하는 EFF-RFID 경계 결정 프로토콜로 구성된다. Recently, many researchers pointed out that contactless smart-card based RFID tags which is used for proximity authentication in RFID system are vulnerable to various location-based relay attacks such as distance fraud, mafia fraud and terrorist fraud attacks. These relay attacks occur by relaying the physical layer signal during an authentication process between the RFID reader and remotely located legitimate the RFID tag. To prevent these relay attacks, many researchers have been proposed various RFID distance bounding protocols that can measure the round-trip time between the reader and the tag. In 2009, Avoine and Tchamkerten proposed an AT-RFID distance bounding protocol based binary tree. In the AT-RFID protocol, the attacking success probability of an adversary is 75%. It means that the AT-RFID protocol cannot completely prevent the above described relay attacks. Therefore, this paper proposes new two RFID distance bounding protocols(SEC-RFID and EFF-RFID) applied ???? technique that can provide 67% and 44% for the adversary’s attacking success probability, respectively. The proposed protocols consist of tree-based secure SEC-RFID distance bounding protocol that can provide strong security and tree-based EFF-RFID distance bounding protocol that can provide highly storage efficiency.

DFT 기반의 개선된 페이저 연산 기법을 적용한 거리계전 알고리즘

이동규(Dong-Gyu Lee),강상희(Sang-Hee Kang) 대한전기학회 2010 전기학회논문지 Vol.59 No.8

In this paper, we propose a distance relaying algorithm using a Discrete Fourier Transform (DFT)-based modified phasor estimation method to eliminate the adverse influence of exponentially decaying DC offsets. Most distance relays are based on estimating phasors of the voltage and current signals. A DFT is generally used to calculate the phasor of the fundamental frequency component in digital protective relays. However, the output of the DFT contains an error due to exponentially decaying DC offsets. For this reason, distance relays have a tendency to over-reach or under-reach in the presence of DC offset components in a fault current. Therefore, the decaying DC components should be taken into consideration when calculating the phasor of the fundamental frequency component of a relaying signal. The error due to DC offsets in a DFT is calculated and eliminated using the outputs of an even-sample-set DFT and an odd-sample-set DFT, so that the phasor of the fundamental component can be accurately estimated. The performance of the proposed algorithm is evaluated for a-phase to ground faults on a 345 kV, 50 km, simple overhead transmission line. The Electromagnetic Transient Program (EMTP) is used to generate fault signals. The evaluation results indicate that adopting the proposed algorithm in distance relays can effectively suppress the adverse influence of DC offsets.

Performance Evaluation of Distance Relay in the Presence of Voltage Source Converters-Based HVDC Systems

M. Mohan,K. Panduranga Vittal 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.1

Voltage source converters (VSC)-based high voltage direct current (HVDC) link is an economical option for the long distance bulk power transmission, and it can be used to interconnect the offshore wind farms with an AC grid. Due to the penetration of VSC-HVDC system into the AC grid, the performance of the distance relay gets affected when a transmission line close to the point of common coupling (PCC) subjected to power system disturbances. In such condition, the PCC voltage is increased due to the VSC-HVDC control action, that causes the Zone-2 fault can be seen as a Zone-3 fault. As a result, the miscoordination of Zone-2 protection can occur in the distance relays. This paper presents both the analytical and simulation studies carried out on a VSC-HVDC system influence on the distance relay performance under fault conditions using PSCAD/EMTDC. Simulation results show that the presence of VSC-HVDC system greatly affects the performance of the Zone-2 and Zone-3 relay in an AC transmission line. Besides, the maloperation of the Zone-2 and Zone-3 relay is mitigated by varying the AC voltage reference input of the decoupled d-q controller of VSC-HVDC. Also, the effect of fault resistance on Zone-1 ground relay performance is analyzed.

Development of Protection Method for Power System interconnected with Distributed Generation using Distance Relay

Ji-Soo Kim,Gyu-Jung Cho,Jin-Sol Song,Jae-Yun Shin,Dong-Hyun Kim,Chul-Hwan Kim 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.6

The conventional power system allowed only downstream power flow. Therefore, even if a fault occurs, only the forward current flow is considered. However, with the interest in distributed generation (DG), DGs such as Photovoltaic (PV), Wind Turbine (WT) are being connected to a power system. DGs have many advantages, but they also have disadvantage such as generation of reverse flow. Reverse flow can severely disrupt existing protection systems that only consider downstream power flow. The major problems that may arise from reverse power flow are blinding protection and sympathetic tripping. In order to solve such problems, the methods of installing a directional relay or a fault current limiter is proposed. However, this method is inconceivable because of the economics shortage. Therefore, in this paper, a distance relay installed in existing power system is used to solve the protection problem. Modeling of distance relay has been carried out using ElectroMagnetic Transients Program (EMTP), and it has been verified through simulations that the above problems can be solved by a distance relay.

Knowledge-Based Approach Using Support Vector Machine for Transmission Line Distance Relay Co-ordination

Ravikumar B.,D. Thukaram,H. P. Khincha 대한전기학회 2008 Journal of Electrical Engineering & Technology Vol.3 No.3

In this paper, knowledge-based approach using Support Vector Machines (SVMs) are used for estimating the coordinated zonal settings of a distance relay. The approach depends on the detailed simulation studies of apparent impedance loci as seen by distance relay during disturbance, considering various operating conditions including fault resistance. In a distance relay, the impedance loci given at the relay location is obtained from extensive transient stability studies. SYMs are used as a pattern classifier for obtaining distance relay co-ordination. The scheme utilizes the apparent impedance values observed during a fault as inputs. An improved performance with the use of SVMs, keeping the reach when faced with different fault conditions as well as system power flow changes, are illustrated with an equivalent 265 bus system of a practical Indian Western Grid.

Power Swing Detection Using rms Current Measurements

Taheri, Behrooz,Razavi, Farzad The Korean Institute of Electrical Engineers 2018 Journal of Electrical Engineering & Technology Vol.13 No.5

During a power swing, distance relays may mistakenly spread fault throughout the power grid, causing a great deal of damage. In some cases, such mistakes can cause global outages. For this reason, it is critical to make a distinction between power swings and faults in distance relays. In this paper, a new method is proposed based on RMS measurement to differentiate between faults and power swings. The proposed method was tested on two standard grids, demonstrating its capability in detecting a power swing and simultaneous fault with power swing. This method required no specific configurations, and was independent of grid type and zoning type of distance relays. This feature in practice allows the relay to be installed on any grid with any kind of coordination. In protective relays, the calculations applied to the microprocessor is of great importance. Distance relays are constantly calculating the current RMS values for protection purposes. This mitigates the computations in the microprocessor to detect power swings. The proposed method was able to differentiate between a fault and a power swing. Furthermore, it managed to detect faults occurring simultaneously with power swings.

송전선로에 UPFC연계시 거리계전기 동작특성에 관한 연구

서정남,정창호,김진오 한국조명전기설비학회 2002 조명·전기설비학회논문지 Vol.16 No.1

본 연구에서는 FACTS 기기 중 가장 우수한 기기로서 활발히 연구가 진행되고 있는 UPFC가 송전계통에 연계되었을 경우 거리계전기가 보는 임피던스 특성을 분석하였다. 최근, 계통 안정도와 전력 전송용랑을 증가시키기 위해 UPFC가 사용됨에 따라 기존의 보호계전기에 어떠한 영향을 줄 것인가를 미리 연구하여 보호계전기가 오동작 및 부동작이 나지 않도록 대책을 강구할 필요성이 있다. UPFC가 연계되어 운전되면 송전계통의 조건이 UPFC의 운전조건에 따라 변하게 되고 송전선로 보호용으로 설치된 거리계전기가 보는 임피던스값도 영향을 받을 것이다. 따라서 UPFC가 설치된 선로에서 사고를 검출하는 거리계전기가 임피던스를 계산시 UPFC기기에 의한 보상전압 크기와 위상을 충분히 고려해서 계산되어져야 한다. 본 연구에서는 UPFC기기가 연계된 송전선로에서 사고 발생시, 거리 계전기의 오동작을 방지하기 위해 보호협조가 필요함을 제시하였으며 PSCAD/EMTDC를 통해 UPFC와 계통을 모델링하여 사고를 모의후 거리계전기가 보는 임피던스 특성을 분석하였다. This paper represents impedance calculation of the distance relay using PSCAD/EMTDC software for transmission line involving the UPFC(Unified Power Flow Controller)device, which is the most vigorous component of FACTS. The presence of the UPFC significantly affects the line parameters of transmission system, which are also influenced by the distance relay setting. Moreover, depending on the UPFC location and its parameters, zones of setting the distance relay will be changed. The presence of the UPFC in the fault loop affects both voltage and current seen by relay. Therefore, the distance relay should be taken into account the variable injected voltage of the UPFC.

Power Swing Detection Using rms Current Measurements

Behrooz Taheri,Farzad Razavi 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.5

During a power swing, distance relays may mistakenly spread fault throughout the power grid, causing a great deal of damage. In some cases, such mistakes can cause global outages. For this reason, it is critical to make a distinction between power swings and faults in distance relays. In this paper, a new method is proposed based on RMS measurement to differentiate between faults and power swings. The proposed method was tested on two standard grids, demonstrating its capability in detecting a power swing and simultaneous fault with power swing. This method required no specific configurations, and was independent of grid type and zoning type of distance relays. This feature in practice allows the relay to be installed on any grid with any kind of coordination. In protective relays, the calculations applied to the microprocessor is of great importance. Distance relays are constantly calculating the current RMS values for protection purposes. This mitigates the computations in the microprocessor to detect power swings. The proposed method was able to differentiate between a fault and a power swing. Furthermore, it managed to detect faults occurring simultaneously with power swings.

Method for Protection of Single‑Line‑Ground Fault of Distribution System with DG Using Distance Relay and Directional Relay

Jung‑Hun Lee,Min‑Su Park,Hong‑Seon Ahn,Kyung‑Won Park,Jun‑Seok Oh,Seung‑Gyu Jeon,Dong‑Kyu Kim,Jae‑Eon Kim 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.4

When large scales DG are connected to the distribution system of unidirectional power currents, bi-directional power currents are formed, making it impossible to use conventional overcurrent protection methods alone to detect and isolate fault sections for ground and short-circuit faults. To solve these problems, this study proposed the method of protection against single-line-ground fault of common neutral line multi-contact local power distribution system using distance relay and directional relay. The proposed protection method was applied to the common neutral multi-ground distribution system to validate the protection against single-line-ground fault through the PSCAD/EMTDC software package and efectively detect and isolate only the zone of single-line-ground fault without malfunctions.

변류기 포화가 거리계전 알고리즘에 미치는 영향 분석

孫天明,姜相熙 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-

Abstract - Distance relays need accurate current and voltage for determining the trip ignition. Therefore we must analyze nonlinear phenomena which cause distortion in signals first of all. This paper presents the effect of current transformer saturation in power system. The saturation of a current transformer distorts the input current of a distance relay. This paper describes modeling methods of a current transformer, simulation results of two distance relay algorithms (discrete fourier transform and modified differential equation methods) and some interesting results of the algorithm by using an CT secondary current compensating technique.