• Proceedings of the KIEE Conference
• /
• 2000.07a
• /
• pp.259-261
• /
• 2000

UPFC(Unified Power Flow Controller) consists of two voltage sourced converter(VSC)s inserted into AC system through series and parallel coupling transformer, where two VSCs are linked by capacitor at DC-side. Since VSC acts as an AC voltage source behind a reactance, where both magnitude and phase angle of the source are controllable, UPFC can be represented by the equation related to input-output relation of two VSCs. Voltage control of DC-link capacitor provides the path of real power flow between two VSCs. While UPFC is controlled for maintaining the given reference value in steady state, it should be controlled for damping power oscillation in dynamics. For such a control objective, the control strategy based on the energy function was proposed and has been shown to be effect and robust for damping power oscillation of power system. In this paper, UPFC model based on the VSC was analysed and applied to power-flow control and stability analysis. The control strategy based on the energy function is adopted for damping power oscillation of power system. The effectiveness of proposed control strategy was verified by simulation study

• 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.

• Current Photovoltaic Research
• /
• v.4 no.4
• /
• pp.131-139
• /
• 2016

This paper shows the series power device in the massive roof-top PVs and domestic loads. D-UPFC as the series power device controls the distribution voltage during voltage rise (or fall) condition. D-UPFC consists of the bi-directional ac-ac converter and the transformer. In order to verify the D-UPFC voltage control, the distribution model is used in the case study. D-UPFC enables the voltage control in the distribution voltage range. Dynamic voltage control from voltage rise and voltage fall conditions is performed. Scaled-down experimental test of the D-UPFC is verified the voltage control and it is well performed without high voltage spikes in the inductive load.

• Proceedings of the KIEE Conference
• /
• 2006.10d
• /
• pp.152-154
• /
• 2006

This paper presents an electric power control scheme in the transmission line using a UPFC(Unified Power Flow Controller). From the practical application viewpoint, the simultaneous realization of the power response desired. The author propose a new power control algorithm for UPFC. To verify the effectiveness of the proposed algorithm, a protype inverter is built and some experiments are carried out.

• Journal of Electrical Engineering and Technology
• /
• v.4 no.3
• /
• pp.315-322
• /
• 2009

Penetration and installation of a new dynamic technology known as Flexible AC Transmission Systems (FACTS) in a practical and dynamic network requires and force expert engineer to develop robust and flexible strategy for planning and control. Unified Power Flow Controller (UPFC) is one of the recent and effective FACTS devices designed for multi control operation to enhance the power system security. This paper presents a dynamic strategy based on Particle Swarm Optimization (PSO) for optimal parameters setting of UPFC to enhance the system loadability. Firstly, we perform a multi power flow analysis with load incrementation to construct a global database to determine the initial efficient bounds associated to active power and reactive power target vector. Secondly a PSO technique applied to search the new parameters setting of the UPFC within the initial new active power and reactive power target bounds. The proposed approach is implemented with Matlab program and verified with IEEE 30-Bus test network. The results show that the proposed approach can converge to the near optimum solution with accuracy, and confirm that flexible multi-control of this device coordinated with efficient location enhance the system security of power system by eliminating the overloaded lines and the bus voltage violation.

• Proceedings of the KIEE Conference
• /
• 2000.11a
• /
• pp.33-35
• /
• 2000

We propose a intelligent controller for FACTS(Flexible AC Transmission System) device to stabilize a power system. In order to identify the nonlinear characteristics of the power system and to estimate a control signal, an artificial neural network is utilized. The control signal which is provided for FACTS device installed in the network is produced. The proposed controller is applied to Unified Power Flow Controller(UPFC) to verified the effectiveness of the proposed control system. The results show that the proposed nonlinear FACTS controller is able to enhance the transient stability of three machine nine bus power system.

• Journal of Electrical Engineering and Technology
• /
• v.5 no.3
• /
• pp.389-399
• /
• 2010

Available transfer capability (ATC) is a measure of the transfer capability remaining in a transmission system. Application of unified power flow controllers (UPFCs) could have positive impacts on the ATC of some paths while it might have a negative impact on the ATC of other paths. This paper presents an approach to evaluate the impacts of UPFCs on the ATC from a cost/worth point of view. The UPFC application worth is considered as the maximum cost saving in enhancing the ATC of the paths due to the UPFC implementation. The cost saving is considered as the cost of optimal application of other system reinforcement alternatives (except for UPFC) to reach the same ATC level obtained by UPFC application. UPFC application costs include the maximum cost of alleviating the probable negative impact on the ATC of some paths caused by implementing UPFCs. Optimal system reinforcement is used for systems with UPFCs to determine the aforementioned cost. The proposed method is applied to the IEEERTS and the results are evaluated through a sensitivity analysis. The cost/worth of UPFC application is also used to develop an index for optimal UPFC location and the results are compared with those of other indices. A comparison is finally made with the results obtained using an existing ATC allocation profit-based approach to determine UPFC application worth.

• Journal of Electrical Engineering and Technology
• /
• v.11 no.5
• /
• pp.1057-1062
• /
• 2016

• International Journal of Control, Automation, and Systems
• /
• v.6 no.4
• /
• pp.495-505
• /
• 2008

This paper describes modeling Voltage Sourced Inverter (VSI) type Flexible AC Transmission System (FACTS) controllers and control methods for power system dynamic stability studies. The considered FACTS controllers are the Static Compensator (STATCOM), the Static Synchronous Series Compensator (SSSC), and the Unified Power Flow Controller (UPFC). In this paper, these FACTS controllers are derived in the current injection model, and it is applied to the linear and nonlinear analysis algorithm for power system dynamics studies. The parameters of the FACTS controllers are set to damp the inter-area oscillations, and the supplementary damping controllers and its control schemes are proposed to increase damping abilities of the FACTS controllers. For these works, the linear analysis for each FACTS controller with or without damping controller is executed, and the dynamic characteristics of each FACTS controller are analyzed. The results are verified by the nonlinear analysis using the time-domain simulation.

• Proceedings of the KIEE Conference
• /
• 2000.07a
• /
• pp.25-27
• /
• 2000

The unified flow controller(UPFC) is one of the most effective devices among the FACTS device family. In principle the UPFC is capable of controlling active and reactive power as well as the voltage magnitude can. Comparisons are made between the proposed and the existing UPFC models, which demonstrate the improvement in both flexibility and efficiency.