• 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.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.2
• /
• pp.513-521
• /
• 2017

HVDC protection setting is difficult to be calculated analytically because of its strong nonlinearity. The currently used setting method is based on the empirical setting of previous projects and then verified by digital simulation. It entails a huge workload and low efficiency. To facilitate protection setting, this paper systematically summarizes the HVDC protection characteristics and then presents a classification of HVDC protections according to the protection principles. On the basis of the fault quantities, a novel setting procedure suitable for travelling wave protection, derivative and level protection, and differential protection is proposed. The proposed procedure is illustrated and verified in detail with the example of travelling wave protection. An HVDC protection setting system that has the functions of automatic protection setting and data management is developed utilizing the C# programming language.

• Journal of Advanced Marine Engineering and Technology
• /
• v.33 no.8
• /
• pp.1232-1238
• /
• 2009

As power facilities are getting higher at capacity, the monitoring and diagnosis of generators for fault detection and protection has attracted intensive interest. In case of an after-fault in high capacity rotating machines, the recovering cost is usually very expensive and additional time is necessary for returning in a normal situation. In this paper, we developed the protection program for the generator fault protection system and each module of the digital protective relay H/W for loading the protection program. The protective relay H/W was designed to have EMC characteristics for prohibiting from fault operation in bad power systems.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.56 no.5
• /
• pp.834-840
• /
• 2007

A generator plays an important role in transferring an electric power to power system networks. The generator protection systems in Korea have been imported and operated through a tum-key from overseas entirely. Therefore, a study of the generator protection field has in urgent need for a stable operation of the imported goods, and for preparation of next generation protection system. The paper describes the fault detection algorithm using WT(Wave!et Transform) of currents for a generator protection. The fault current signals after executing a terminal fault modeling collect using a MA TLAB package, and calculate the wavelet coefficients through the process of a multi -level decomposition (MLD). The proposed algorithm for a fault detection using the Daubechies WT (wavelet transform) was executed with a C language for the command line function and for the real time realization after analyzing MATLAB's graphical interface. The advanced technique had complemented the defects of a DFT by applying a Daubechies WT. and had improved faster a speed and more accurate of fault discriminant than a conventional DFR.

• Proceedings of the KIEE Conference
• /
• 2009.07a
• /
• pp.442_443
• /
• 2009

A large wind farm should satisfy the requirements for a grid and accomplish the optimization of the wind farm system. In that point of view, the wind farm intertie protection system, which must consider the Fault Ride-Through (FRT) requirement for more reliable protection, should be improved. This paper proposes a modified distance relay suitable for protection of a wind farm intertie considering a FRT requirement. The frequency change is used to discriminate the intertie fault from a outside zone fault. The performance of the proposed algorithm is verified using a PSCAD/EMTDC simulator.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.736-740
• /
• 2004

In order to overcome the problems of simulation methods, the power system transient stability assessment method using critical fault clearing time functions has been developed. Using the above method, this paper has developed the new method which can assess accurately and efficiently the effects of control and protection systems on transient stability which is the most important characteristic to assess in power systems. At first, critical fault clearing time functions CCT(W:load) are defined by taking notice of the fact that transient stability is mainly controlled by fault clearing time and load. Next, the method to be enable to assess accurately and efficiently the effects of control and protection systems on transient stability has been newly developed by using the above functions. Finally, it has been applied to the effect assessment in the occurrence of a three-phase fault in a model power system. Results of application have been clarified its effectiveness.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.7
• /
• pp.966-973
• /
• 2012

In microgrid demonstration site, distributed generations can make bidirectional power flows on the system. If an accident occurs, the fault current from the inverter based distributed generation is small. However, the conventional protection scheme in distribution network is designed to operate at high fault current. This means that the traditional protection of distribution network is no longer applicable and new protection methods must be developed. In this paper, for two cases, algorithms for protection coordination of demonstration site is proposed and verified through PSCAD/EMTDC simulation. In first case, protection devices are assumed to have the abilities of directional relaying and communication. In second case, protection devices do not have those abilities. Proposed protection coordination algorithms detect the fault locations and protect the microgrid fairly well.

• Proceedings of the KSR Conference
• /
• 2002.10b
• /
• pp.989-994
• /
• 2002

In case the fault occurs in railway high voltage power supply network, protective relaying system must selectively detect 1 wire ground fault of grounding or non-grounding system. And this study presents railway high voltage power supply system model using PSCAD/EMTDC Vet 3.08 for circuit analysis and fault studies. In this paper, we propose protection method of non-grounding system of railway high voltage power supply system. The result shows its usefulness.

• Proceedings of the KIEE Conference
• /
• 2006.07b
• /
• pp.1089-1090
• /
• 2006

This paper analyzes impedance convergence characteristics and harmonics of electric locomotives operation and fault condition. To simulate the various fault and operation condition, AT feeding system and various locomotives are modeled using PSCAD/EMTDC. Analysis shows that impedance are converged into protection area in the case of short fault between catenary and rail or catenary and feeder line but in the case of disconnection fault, impedance is rater bigger so protective relay can't detect the fault. Therefore more analysis of overload and high impedance fault caused disconnection fault is needed.

• KEPCO Journal on Electric Power and Energy
• /
• v.8 no.1
• /
• pp.43-48
• /
• 2022

Although the distribution system has been structured as complicated as a mesh in the past, the connection points for each line are always kept open, so that it is operated as a radial distribution system (RDS). For RDS, the line utilization rate is determined according to the maximum load on the line, and the utilization rate is usually kept low. In addition, when a fault occurs in the RDS, a power outage of about 3 to 5 minutes occurs until the fault section is separated, and the healthy section is transferred to another line. To improve the disadvantages of the RDS, research on the construction of a networked distribution system (NDS) that linking multiple lines is in progress. Compared to the RDS, the NDS has advantages such as increased facility utilization, load leveling, self-healing, increased capacity connected to distributed generator, and resolution of terminal voltage drop. However, when a fault occurs in the network distribution system, fault current can flow in from all connected lines, and the direction of fault current varies depending on the fault point, so a high-precision fault current direction determination method and high-speed communication are required. Therefore, in this paper, we propose an accurate fault current direction determination method by comparing the peak value polarity of the fault current in the event of a fault, and a communication-based protection coordination method using this method.