• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.10
• /
• pp.1832-1837
• /
• 2011

The fault current has increased due to the large power demand in power distribution system and network distribution system. To protect the power system effectively from the increased fault current, the superconducting fault current limiter (SFCL) has been notified. However, the conventional SFCL has some problems such as cost, operation, recovery, loss. To solve some problems, the hybrid superconducting fault current limiter using the fast switch was proposed. However, hybrid SFCL also has a problem that is protection coordination in power distribution system with hybrid SFCL. In this paper, the fault current limiting characteristics of hybrid SFCL with first half cycle non-limiting operation according to the fault angle, the resistance of superconducting element, and the magnitude of Current Limit Resistor (CLR) which are the components of hybrid SFCL were analyzed through the experiments.

• Journal of the Korean Society of Industry Convergence
• /
• v.21 no.4
• /
• pp.149-158
• /
• 2018

With the propagation and spread of the new regeneration energy and increase in electricity demand, power systems tend to be decentralized, and accordingly, the use of a power system stabilizer tends to expand for the stabilization of the distribution system. Thus, typical power system stabilizer, Static Var Compensator (SVC) is developed on a variety of topologies. In addition, the trend of technology leads from SVC to Static Synchronous Compensator(STATCOM) technology development. Recently, to overcome STATCOM's conversion losses and economic disadvantages, studies of a hybrid method using STATCOM and SVC in parallel have actively been conducted. This study proposes a new Soft-Step Switching method to limit inrush current problematic in Thyristor Controlled Capacitor (TCC) method in SVC function. In addition, to reduce Statcom's capacity, groups of reactive power compensation reactor and condenser for SVC were designed.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.7 no.4
• /
• pp.313-321
• /
• 2002

A braking algorithm for a PM synchronous motor is presented. The resistance of the stator windings operates as a braking resistors and dissipates the regenerated power from the rotor without any braking components including the electronic power components and control circuits. The proposed braking algorithm maximizes the power dissipation in the stator windings and also generates the maximum braking torque under the limit conditions of DC link capacitor voltage and inverter currents so that it can minimize the braking time.

• Journal of Institute of Control, Robotics and Systems
• /
• v.20 no.8
• /
• pp.849-853
• /
• 2014

In micro-scale electromechanical systems, the power to perform accurate position sensing often greatly exceeds the power needed to generate motion. This paper explores the implications of sampling rate and amplifier noise density selection on the performance of a system identification algorithm using a capacitive sensing circuit. Specific performance objectives are to minimize or limit convergence rate and power consumption to identify the dynamics of a rotary micro-stage. A rearrangement of the conventional recursive least-squares identification algorithm is performed to make operating cost an explicit function of sensor design parameters. It is observed that there is a strong dependence of convergence rate and error on the sampling rate, while energy dependence is driven by error that may be tolerated in the final identified parameters.

• Proceedings of the KIEE Conference
• /
• 2002.07a
• /
• pp.259-261
• /
• 2002

Recently, according to the spread of semiconductor applied technology like motor speed control contrivance, power conversion installation and so on, harmonic ingredients occurred in switching operation flow into a distribution system and increase voltage distortion of distribution system and bring on obstacles like damage, lowering of capability, false operation and so on of various electrical installation. So, in order to consider a countermeasure to limit occurrence quantity of harmonic source, harmonic interception and others, precision measurement and analysis on voltage, current, power, power factor, the each ingredient of harmonic order, the percentage of total harmonic distortion and so forth are needed. In this paper monitoring system to measure and analyze power quality connected with power harmonics was developed and it's performance is verified by measuring and analyzing three-phase voltage and current of R, S, T in the three-phase and four-wire system using the developed measurement system.

• Proceedings of the KIEE Conference
• /
• 2002.07a
• /
• pp.50-52
• /
• 2002

GPSS(Graphic-based Power System Simulator) had been introduced before in an ex-thesis. GPSS is a Power System Simulator that is designed to provide friendly and highly interactive Graphic User Interface (GUI). In this Paper, GPSS was improved not for the education or the test, but as the instrument for a large-scale systematic analysis. To limit the difference between a theory and practical affairs, we reformed and added a lot of functions to the GPSS. And we have verified the real-systematic data.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.03b
• /
• pp.8-8
• /
• 2010

In this paper, the limiting characteristics of the fault current in a power system with a superconducting fault current limiter(SFCL) applied into neutral line of main transformer in a distribution power line were analyzed. The SFCL applied into the neutral line of main transformer power system can limit the unsymmetrical fault current from the single-line ground fault or the double-line ground fault. In addition, it could be decreased a number of SFCL and a load. This method could be expected to reduction of a power loss in the neutral line, because of a neutral line current is zero in ordinary times.

• Proceedings of the KIEE Conference
• /
• 2004.07d
• /
• pp.2260-2262
• /
• 2004

After steam turbines in power plant drives generator and maintains it at rated speed using high temperature and high pressure steam energy, they regulate the output of generator when synchronized in parallel with the power system. By the way, as the steam flow into turbine can not be reduced fast even though the electrical load is lost, the turbine gets into dangerous situation due to the increase of its speed. At this time, the duty of the turbine governor is "how to limit the speed within its overspeed trip setpoint and escape from danger." For the purpose of it, there are various ways known. Some overspeed protection methods for steam turbines now being operating in korea are introduced in this paper.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.1661-1662
• /
• 2008

After steam turbines in power plant drives generator and maintains it at rated speed using high temperature and high pressure steam energy, they regulate the output of generator when synchronized in parallel with the power system. By the way, as the steam flow into turbine can not be reduced fast even though the electrical load is lost, the turbine gets into dangerous situation due to the increase of its speed. At this time, the duty of the turbine governor is "how to limit the speed within its overspeed trip setpoint and escape from danger." In order to implement this purpose, there are various ways different from valve position control. So, in this paper, the various methods for overspeed protection are introduced in comparison with valve position control.

• Proceedings of the KIEE Conference
• /
• 1999.11b
• /
• pp.200-202
• /
• 1999

This paper describes the optimization problem of real power rescheduling and present an algorithm based linear programming for studying the load-shedding and generation reallocation problem when a portion of the transmission system is disabled and at power flow solution cannot be obtained for the overload of some lines. And in case initial is infeasible, solution could not be converge. So this paper gives an algorithm being lie infeasible quantities within limit. The paper describes a LP-based algorithm to obtain the solution in power dispatch related to overload situations in power system and it is easily extened under various objective. The optimization procedures is based in linear programming with bounded variables and use the multi-segment curve method for a objective function and the validity of the algorithm is verified with two examples : 10-bus system and 57-bus system.