• Proceedings of the KIEE Conference
• /
• 1999.11b
• /
• pp.226-228
• /
• 1999

This paper presents a dynamic simulation algorithm for studying the effect of Unified Power Flow Controller(UPFC) on the low frequency power system oscillations and transient stability studies. The algorithm is a Newton-type one and gives a fast convergence characteristics. The algorithm is applied to inter-area power oscillation damping regulator design of a sample two-area power system. The results show that UPFC is very effective for damping inter-area oscillations.

• KIEE International Transactions on Power Engineering
• /
• v.3A no.3
• /
• pp.161-167
• /
• 2003

This paper presents a study performed to investigate the steady-state operational strategies of UPFCs in the Jeollanam-Do system in Korea. The objective of the study was to determine the UPFC operating points under normal and contingency conditions. The study consists of developing load flow models to simulate different load levels with and without UPFCs in the system, assessing the effectiveness of UPFCs by contingency analysis, and introducing optimal corrective actions for removing voltage problems caused by contingencies. The paper describes analytical tools, models and approach. It also includes analysis and discussion of the study results. The paper contributes to the area of transmission operational studies with FACTS applications.

• Proceedings of the KIEE Conference
• /
• 1998.07c
• /
• pp.887-889
• /
• 1998

This paper focuses on the simulation and ciontrol of the Unified Power Flow Controller (UPFC). This paper gives a brief outline of the initial results of the effect of the UPFC on the damping of the power system oscillations. The nonlinear simulation results show the effectiveness of each UPFC control variable and gives the future research direction.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.7
• /
• pp.824-831
• /
• 1999

This paper presents new methods to resolve the important limits in the decoupled UPFC model for power flow, by which conventional power flow program can be performed with addition of two buses per one UPFC. In order to operate UPFC to the desired value, the series voltage and shunt current of UPFC should be computed. So a method of calculating these by simple equations after power flow is derived. However, the calculated magnitude of series voltage and/or shunt current of UPFC may not be allowed because of the UPFC limit \ulcorner to the ratings of inverters. In this case, the active power and the reactive power (or the voltage magnitude) of UPFC buses should be revised to resolve the limit. This paper proposes the Newton Raphson method to resolve these limits. Particularly, when resolving the series voltage magnitude, three strategies are proposed according to the priority of the active power and the reactive power (or the voltage magnitude).

• KIEE International Transactions on Power Engineering
• /
• v.11A no.4
• /
• pp.21-26
• /
• 2001

As competition is introduced in the electricity supply industry, congestion becomes a more important issue. Congestion in a transmission network occurs due to an operating condition that causes limit violations on the transmission capacities. Congestion leads to inefficient use of the system, or causes additional costs (Congestion cost). One way to reduce this inefficiency or congestion cost is to control the transmission flow through the installation of UPFC (Unified Power Flow Controller). This paper also deals with an optimal siting of the UPFC for reducing congestion cost by using shadow prices. A performance index for an optimal siting is defined as a combination of line flow sensitivities and shadow prices. The proposed algorithm is applied to the sample system with a condition, which is concerning the quadratic cost functions. Test results show that the siting of the UPFC is optimal to minimize the congestion cost by the proposed algorithm.

• Proceedings of the KIEE Conference
• /
• 2008.11a
• /
• pp.217-219
• /
• 2008

Among the Flexible AC Transmission Systems (FACTS) devices, Unified Power Flow Controller (UPFC) is considered as the most powerful and versatile one as it provides simultaneous, real time control of the transmission parameters, voltages, impedances, and phase angles which determine the power flow in AC transmission systems. This paper presents modelling of UPFC and describes its characteristics. The UPFC implemented in this paper is based on Sinusoidal Pulse Width Modulation (SPWM) and Electro-Magnetic Transients Program (EMTP)/ATPDraw is used to model and analyze it. The simulation results confirm advantages of UPFC in operational performance with respect to the steady state Power flow regulation and the transient stability control.

• Proceedings of the KIEE Conference
• /
• 1999.07c
• /
• pp.1023-1025
• /
• 1999

This paper provides the steady-state UPFC model referred as UPFC injection model for power flow control. The application of UPFC for the line overload alleviation is demonstrated through a numerical example. It is shown that UPFC has the capability of regulating the power flow, therefore alleviating the line overload.

• Proceedings of the KIEE Conference
• /
• 1999.07c
• /
• pp.1167-1169
• /
• 1999

This paper presents the new unified power flow controller(UPFC) load flow algorithm using UPFC transmission line constant model. The UPFC transmission line constant model represents a function of transmission line constant(G.B) UPFC's effect in power system. It can easily be incorporated in a load flow program. The algorithm is suited for monitoring the power system state as well as determining the magnitude and Phase angle of UPFC serial voltage source.

• Journal of Electrical Engineering and Technology
• /
• v.4 no.3
• /
• pp.310-314
• /
• 2009

This paper presents the improvement of the voltage profiles of power system networks by the inclusion of Unified Power Flow Controller (UPFC). The mathematical model of the UPFC is incorporated in the load flow algorithm and the L-index is calculated for the different values of the control parameter r $and{\gamma}$. The positioning of the UPFC device is changed to minimize the sum of the squares of the L-indices at all load buses. The test cases considered for the improvement of voltage profile with the WSCC 9-bus and IEEE 30 bus system. With the best position of UPFC along with the control parameters the improvement in voltage profile of the power system networks are obtained. The results obtained are quite encouraging compared with other techniques used to identify the best location of UPFC.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.49 no.6
• /
• pp.272-279
• /
• 2000

This paper describes a controller design and dynamic performance analysis of UPFC based on 3-level inverters. Major attention is focused on the controller design for both shunt and series inverters, including regulator design for the dc link voltage sharing across the dc capacitors. An energy-based approach was investigated for effectively designing the controller. A detailed UPFC model has been developed with EMTP using 24-pulse 3-level inverters to verify this approach. Simulation results about dynamic performance of UPFC confirm effects for increasing transmission capacity and damping low-frequency oscillation. The developed simulation model would be very effective to analyze the dynamic performance of UPFC.