• Journal of the Korean Society of Systems Engineering
• /
• v.16 no.2
• /
• pp.47-58
• /
• 2020

Most of the reactor trips in Korean NPPs related to core protection systems were caused not because of proximity of boiling crisis and, consequently, a damage in the core, but due to particular miscalculations or component failures related to the core protection system. The most common core protection system applied in Korean NPPs is the Core Protection Calculator System (CPCS), which is installed in OPR1000 and APR1400 plants. It generates a trip signal to scram the reactor in case of low Departure from Nucleate Boiling Ratio (DNBR) or high Local Power Density (LPD). However, is a reactor trip necessary to protect the core? Or could a fast power reduction be enough to recover the DNBR/LPD without a scram? In order to analyze the online calculation of DNBR/LPD, and the use of fast power reduction as trip avoidance methodology, a concept of CPCS with fast power reduction function was developed in Matlab® Simulink using systems engineering approach. The system was validated with maximum of 0.2% deviation from the reference and the dynamic deviation was maximum of 12.65% for DNBR and 6.72% for LPD during a transient of 16,000 seconds.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.6
• /
• pp.2118-2126
• /
• 2017

The large-scale power system blackouts have indicated that conventional protection relays that based on local signals cannot fit for modern power grids with complicated setting or heavily loaded-flow transfer. In order to accurately detect various faulted lines and improve the fault-tolerance of wide-area protection, a novel multi-section weighed fault matching and detecting algorithm is proposed. The real protection vector (RPV) and expected section protection vectors (ESPVs) for five fault sections are constructed respectively. The function of multi-section weighed fault matching is established to calculate the section fault matching degrees between RPV and five ESPVs. Then the fault degree of protected line based on five section fault degrees can be obtained. Two fault detecting criterions are given to support the higher accuracy rate of detecting fault. With the enumerating method, the simulation tests illustrate the correctness and fault-tolerance of proposed algorithm. It can reach the target of 100% accuracy rate under 5 bits error of wide-area protections. The influence factors of fault-tolerance are analyzed, which include the choosing of wide-area protections, as well as the topological structures of power grid and fault threshold.

• ETRI Journal
• /
• v.37 no.1
• /
• pp.97-106
• /
• 2015

In this paper, MOS-triggered silicon-controlled rectifier (SCR)-based electrostatic discharge (ESD) protection circuits for mobile application in 3.3 V I/O and SCR-based ESD protection circuits with floating N+/P+ diffusion regions for inverter and light-emitting diode driver applications in 20 V power clamps were designed. The breakdown voltage is induced by a grounded-gate NMOS (ggNMOS) in the MOS-triggered SCR-based ESD protection circuit for 3.3 V I/O. This lowers the breakdown voltage of the SCR by providing a trigger current to the P-well of the SCR. However, the operation resistance is increased compared to SCR, because additional diffusion regions increase the overall resistance of the protection circuit. To overcome this problem, the number of ggNMOS fingers was increased. The ESD protection circuit for the power clamp application at 20 V had a breakdown voltage of 23 V; the product of a high holding voltage by the N+/P+ floating diffusion region. The trigger voltage was improved by the partial insertion of a P-body to narrow the gap between the trigger and holding voltages. The ESD protection circuits for low- and high-voltage applications were designed using $0.18{\mu}m$ Bipolar-CMOS-DMOS technology, with $100{\mu}m$ width. Electrical characteristics and robustness are analyzed by a transmission line pulse measurement and an ESD pulse generator (ESS-6008).

• The Transactions of the Korean Institute of Electrical Engineers P
• /
• v.61 no.1
• /
• pp.35-40
• /
• 2012

An AC generator is an important component in producing an electric power and so it requires highly reliable protection relays to minimize the possibility of demage occurring under fault conditions. It is a need for research of digital generator protection system(DGPS) for the next-generation ECMS and an efficient operation of protection control system in power station. However, most of protection and control system used in power plants have been still imported as turn-key and operated in domestic. This may cause the lack of the correct understanding on the protection systems and methods, and thus have difficulties in optimal operation. In this paper, presented ratio differential relaying(RDR) is main protective element in generator protection IED. The fault detection technique, operation zone and setting value of the RDR were studied and, compared with two of the fault detection algorithm. For evaluation performance of the RDR, the data obtained from ATPDraw5.7p4 modeling was used. The proposed methods are shown to be able to rapidly identify internal fault and did not operate a miss-operation for all the external fault.

• Fire Science and Engineering
• /
• v.24 no.4
• /
• pp.116-122
• /
• 2010

The fire protection system of nuclear power plants shall be designed, constructed and operated, through a defense-in depth criterion to suppress the leakage of radioactivity to the outside and to allow the safety shutdown function when a fire occurs. In order to achieve these purposes, most of countries abroad operating the nuclear power plants keep up the integrated regulations, however we have two guidelines, the fire protection service act and the nuclear energy act, as mandatory requirements to apply to the fire protection systems in nuclear power plants. It has shown that USA, Canada and Japan which have long experience in operating nuclear power plants have regulations integrated technically for fire protection system of nuclear power plants. It is proposed that the things once verified the risk analysis of the fire hazard by the nuclear law in the design for fire suppression system in plants should be authorized by the fire protection service act as an exception.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.32A no.10
• /
• pp.25-34
• /
• 1995

A new vertical power MOSFET with over-current protection capability is proposed. The MOSFET consists of main power MOSFET cell, sensing MOSFET cell and lateral npn bipolar transistor. The proposed MOSFET may be fabricated by a conventional DMOS process without any additional fabrication step. Overcurrent state is sensed by the newly designed lateral bipolar transistor. Mixed-mode simulations proved that the overcurrent protection is achieved by the proposed MOSFET successfully with a small protection area less than 0.2 % of the total die area.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.545-546
• /
• 2015

Arc flash hazard study is required for the electric power system of industrial plant nowadays. Arc flash incident energy and level are calculated by arc flash hazard study. The arcing fault clearing time is determined by the response time of protection devices. This paper is protection devices coordination study to reduce potential incident energy for industrial electric power system.

• Journal of Electrical Engineering and Technology
• /
• v.2 no.2
• /
• pp.172-177
• /
• 2007

Wavelet transforms provide basis functions for time-frequency analysis and have properties that are particularly useful for the compression of analogue point on wave transient and disturbance power system signals. This paper evaluates the compression properties of the discrete wavelet transform using actual power system data. The results presented in the paper indicate that reduction ratios up to 10:1 with acceptable distortion are achievable. The paper discusses the application of the reduction method for expedient fault analysis and protection assessment.

• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.292-293
• /
• 2011

We proposed a new power system, Superconducting Power System. The SPS consists of superconducting power cables, fault current limiters, and transformers. The basic concept is to replace 154kV conventional cables with 22.9kV superconducting cables and to convert a 154kV substation into a 22.9kV switching station in downtown area. For the application of the SPS to real power system, it is very important to construct the protection system of the SPS. This study presents a protection system for the new Superconducting Power System (SPS).

• Proceedings of the KIEE Conference
• /
• 1998.07c
• /
• pp.880-883
• /
• 1998

In this paper, sensitivity based approach to estimate BITC(bilateral interchange transfer capacity) considering the real power flow control function of FACTS device is presented. The real power flow setting of the FACTS device is adjusted so that it transfer the power flow from the first violation point of transmission capacity to other transmission lines in the power system, thus allowing more power to be transferred from the specified generator bus to the specified load bus. The transfer between the two bus locations is increased from this new operating condition until a violation of transmission capacity limits occurs or until the setting of the FACTS device can no longer be adjusted. The proposed algorithm is illustrated using examples of small and real life power system.