• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.7
• /
• pp.478-485
• /
• 2008

The extreme steam temperature deviation experienced in the superheater of a tangentially fired boiler can seriously affect its economic and safe operation. This temperature deviation is one of the main causes of boiler tube failures. The steam temperature deviation is mainly due to the thermal load deviation in the lateral direction of the superheater. The thermal load deviation consists of several causes. One of the causes is the non-uniform heat flow distribution of burnt gas on the superheater tube system. This distribution is very difficult to measure in situ using direct experimental techniques. So, we need thermal load model to estimate the tube temperature. In this paper, we propose a thermal load distribution model by using CFD analysis and plant data. We successfully predict the tube temperature and the steam flow rate in a final superheater system from the thermal load model and one dimensional heat-flow system analysis. The proposed model and analysis method would be valuable in preventing the frequent tube failure of the final superheater tubes.

• Journal of Power System Engineering
• /
• v.15 no.1
• /
• pp.5-10
• /
• 2011

The spatial fuel vapor distribution of the homogeneous charge by a 6-hole injector was examined in a optically accessed single cylinder direct injection spark ignition(DISI) engine. The effects of in-cylinder charge motion, and fuel injection pressure, and coolant temperature were investigated using a planar LIF (Laser Induced Fluorescence) technique. It was confirmed that the in-cylinder tumble flow played a little more effective role in the spatial fuel vapor distribution than the swirl flow during the compression stroke at 10 mm and 2 mm planes under cylinder head gasket and the increased fuel injection pressure activated spatial distributions of the fuel vapor. In additions, richer mixtures were concentrated around the cylinder wall by the increase of the coolant temperature.

• Journal of Electrical Engineering and Technology
• /
• v.12 no.6
• /
• pp.2208-2218
• /
• 2017

To resolve overload in a distribution system, a distribution system operator (DSO) often performs a load transfer using normally open tie points and switches in the distribution line. During this process, the distribution system is momentarily operated in closed-loop operation. A closed-loop current in the distribution system can cause a power failure due to excess breaking current in the circuit breakers and reclosers. Therefore, it is necessary to calculate the closed-loop current exactly. However, if there are a large number of distributed generation (DG) systems in the distribution system, such as energy storage systems (ESS), they might obstruct the closed-loop operation based on bidirectional power flow. For quick and precise operation of a closed-loop system, the ESS has to regulate the power generation while satisfying closed-loop operation in the worst cases. We propose a strategy for balanced power regulation of an ESS. Simulations were carried out using PSCAD/EMTDC, and the results were compared with calculation results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.13 no.4
• /
• pp.127-133
• /
• 1999

Ths paper deals with the active and reactive power control of Battery Energy Storage System (BESS) during its interconnection operation to power distribution system When an interconnection operation of BESS to power distribution system, it is well suited for peak load shaving and distribution voltage compensation by controlling the real and reactive power. Equivalent mxiel of the distribution system and the BESS is derived and power flow equations are presented to control the real and reactive power of BESS. In this paper, to control the active and reactive power of BESS, $P-\delta$ and Q-V control method and ntJIrerical description is presented. To verify the proposed control method, using PSCAD/EMTDC program simulates the active and reactive power control of BESS.f BESS.

• Proceedings of the KIEE Conference
• /
• 2005.07a
• /
• pp.861-863
• /
• 2005

LMP based congestion management method is suggested as an effective tool, because network congestion can be handled by energy price. It is now being widely used in the North American Electricity Markets. Among them, FGR(Flow-gate rights) is considered to be appropriate for our system, as power flow through the congested line is unidirectional and congestion occurs in the known place. In the CBP market, hedging through transmission right is not necessary even though location pricing system is adopted, because there are no risks in the energy price. Rut, transmission rights should be adopted in the advanced market. Key issue when implementing FGR is how to decide transmission right issuance quantify. This paper deals with a method to decide transmission right issuance quantity by using power. Transfer Distribution Factor(PTDF).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.23 no.2
• /
• pp.53-61
• /
• 2009

This paper presents the improved voltage regulation method in power distribution system with multiple PV systems. At present, Line Drop Compensator (LDC) method has been used as voltage regulation method of power distribution system, which regulates the voltage using Under Load Tap Changer (ULTC), regarding the power flow of distribution system as one way. However, the method may be not able to regulate the voltage in a permissible range when the power flow is two ways. Thus, in this paper, we present the improved voltage regulation method of power distribution system using the voltage data of the point connected PV systems.

• Nuclear Engineering and Technology
• /
• v.54 no.5
• /
• pp.1851-1859
• /
• 2022

Experimental research on flow characteristics of open natural circulation system was performed, to figure out the mechanism of the open natural circulation behaviors. The influence factors, such as the heating power, the inlet subcooled and the level of cooling tank on the flow characteristics of the system were examined. It was shown that within the scope of the experimental conditions, there are five flow types: single-phase stable flow, flash and geyser coexisting unstable flow, flash stable flow, flash unstable flow, and flash and boiling coexisting unstable flow. The geyser flow in flash and geyser coexisting unstable flow is different from classic geysers flow. The flow oscillation period and amplitude of the former are more regular, is a newly discovered flow pattern. By drawing the flow instability boundary diagram and sorting out the flow types, it is found that the two-phase unstable flow is mainly characterized by boiling and flash, which determine the behavior of open natural circulation respectively or jointly. Moreover, compared with full liquid level system, non-full liquid level system is more prone to boiling phenomenon, and the range of heat flux density and undercooling degree corresponding to unstable flow is larger.

• Proceedings of the KIEE Conference
• /
• 1998.11a
• /
• pp.211-213
• /
• 1998

This paper introduces the additional remote monitoring and remote setting functions needed to operate the distribution automation system effectively. we compare the additional functions with the old functions. The remote setting of minimum trip value of fault indicator is an example of additional function. It saves time and line-man's power. Also this paper describes the data transmission flow diagram for operation of distribution automation system using wireless communication method.

• Journal of Power System Engineering
• /
• v.13 no.3
• /
• pp.27-32
• /
• 2009

Numerical analysis information of a complex discharge-passage will be very useful to improve hydrogen compression system. General information about an internal gas flow is presented by numerical analysis approach. Relating with hydrogen compressing system, which have an important role in hydrogen energy utilization, this should be a useful tool to observe the flow quickly and clearly. Flow characteristic analysis, including pressure and turbulence kinetic energy distribution of hydrogen gas from cylinder going to the chamber of a reciprocating compressor are presented in this paper. Discharge-passage model is designed based on real model of hydrogen compressor. Pressure boundary conditions are applied considering the real condition of operating system. The result shows pressure and turbulence kinetic energy are not distributed uniformly along the passage of the hydrogen compressing system. Path line or particles tracks help to demonstrate flow characteristics inside the passage. The existence of vortices and flow direction can be precisely predicted. Based on this result, the design improvement should be done. Consequently, development of the better hydrogen compressing system will be achieved.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.8
• /
• pp.1802-1809
• /
• 2009

Abstract The typical distribution systems have the power flow from distribution substations (sources) to customers (load) only as one direction. However, in the case where distributed generations (DG) such as PV system and wind power systems are connected to distribution systems, the DG output variations to distribution systems, so called reverse power flow, may cause the bi-directional power flow. So, the reverse power flow has severe impacts on typical power system, for example power quality problems, protection coordination problems, and so on. Especially, protection devices (sectionalizer) in primary feeder of distribution system interconnected with distributed generations may cause problems of malfunction, and then many customers could have problems like an interruption. So, this paper presents the bi-directional operation algorithm of protection devices to overcome the problems like mal-function. And, also this paper shows the effectiveness of proposed method by using both PSCAD/EMTDC software and test facility of protection devices to simulate the field distribution systems.