Dong Hee Yoon

Smart Operation of HVDC Systems for Large Penetration of Wind Energy Resources

The target for South Koreas domestic energy consumption is to increase the proportion of the total energy consumption supplied by renewable energy to 11% by 2030. Increasing renewable energy generation has become a natural trend, thereby making it an essential factor to be considered in research for the development of a smart grid. The power system of Jeju Island is connected to the mainland (the Korean Peninsula) through HVDC #1, with another line, HVDC #2, presently under construction. The purpose of the first HVDC construction was essentially to supply a portion of the power supply to the Jeju area. However, if the construction of HVDC #2 is completed, the role of the Jeju HVDC system in the Jeju power system will be changed significantly. If flexibility through the operation of an HVDC system is increased, more wind farms can be built on Jeju Island. In addition, depending on the operation of HVDC #1 and #2, the stability of the Jeju power system will be changed greatly. In this paper, the operation of the HVDC lines and its impacts are analyzed.

Study on Jeju Island power system considering multiple HVDC

Jeju Island, which is the largest island in Korea, has an electric system which has special characteristics where a portion of the required electricity is being provided from the mainland through HVDC lines controlled by the frequency mode. Also, owing to its abundant wind resources, it is favorable for the installation of large scale wind farms with some already being operating and many under construction. Furthermore, the island which has been selected for the Smart Grid test bed will involve generation and power system infrastructure utilizing various renewable sources being tested at the site. Owing to the increase in the load demand and increase in the stability of the island system, the second HVDC line is under construction. This paper deals with the analysis of the 2013 power system of Jeju Island with the inclusion of the wind farms and multiple HVDC to examine the stability of the island system. Several contingency cases are being simulated to form an optimal operational strategy for the operation of the two HVDC lines.

Flexible Frequency Operation Strategy of Power System With High Renewable Penetration

Growth of renewable penetration will increase the requirement for flexible resources. It may be a simple solution to build more flexible resources, but it is too expensive. Recently, the new construction of power plant or transmission line has faced opposition by the resistance of the local residents. Depending on the needs, new methodologies are required in order to gain the flexibility of the power grids. This paper proposes the flexible frequency operation strategy with significant renewable penetration to achieve the flexibility of the power grids. Flexible frequency operation provides customized frequency through BTB HVDC, and the overall system is operated with relaxed frequency regulation. By reducing the need and role of the frequency ancillary service reserve, an operator does not need to secure additional governor response reserve for renewable energy. In order to model frequency dynamic of high renewable penetrated power system, the swing equation is modified in this paper. The case studies using MATLAB show effectiveness of flexible frequency operation strategy.

Study of the Design of Data Acquisition and Analysis Systems for Multi-purpose Regional Energy Systems

Recently, the smart grid has become a hot issue and interest in related power sources have increased accordingly. The implementation of a smart grid can enable many generation resources to be linked to the power system, including small-scale reactors for the purpose of co-generation. Research on small-scale reactors is being carried out all over the world. Similarly, Korea is also conducting research on multi-purpose regional energy systems using nuclear energy. This paper proposes a real-time data acquisition and analysis system for small-scale reactors, and is known as the REX-10 (Regional Energy rX 10 MVA). This analysis requires real-time simulations for the power system since it needs data communication with a remote REX-10. A RTDS (Real Time Digital Simulator) has been used for the simulation, and a SCADA/HMI system interfaced with the RTDS is proposed for the purpose of monitoring and control of the regional energy system.

Frequency control of converter fed micro-grid for flexible frequency operation

Recently, uncertainty in power system increase rapidly. On the other hand, the new construction of power plant or transmission line runs into opposition by the resistance of the local people. And those makes the power system operation more difficult. Because of those challenges new methodologies are required to gain the flexibility of the power grids. Flexible frequency operation provides customized frequency through BTB HVDC, overall system is operated in relaxed frequency regulation. In this operation, sensitive loads which need high quality electric power are operated as micro-grid by BTB HVDC. This paper presents control of converter which connect micro-grid to power system in flexible frequency operation. In test system, main power system is operated in flexible frequency regulation and micro gird is operated in high quality frequency. Simulation result shows contribution of proposed control strategy for main-grid frequency control in flexible operation.

A Research for Site Detection Scheme for the High Temperature Superconducting Cable from the Electrical Point of View

This paper proposes an algorithm to search the suitable site for the installation of the High temperature Superconducting (HTS) cable. The HTS cable is able to transmit a large amount of electricity without additional power transmission facilities. However, it is not desirable to install the HTS cable anywhere because the HTS cable is the high price facility. The best location for the installation of the HTS cable is the place that congestion of transmission line is occurred in. If the HTS cable is used in congestion area, an additional transmission facility is not necessary for stable operation of power system. The technology level of the HTS cable has been improved consistently so the installation of the HTS is possible to use in the limited part of power system. In this paper, an algorithm is suggested to search the proper place for the HTS cable and verified by case study in the power system.

Design of a generator control system for small nuclear distributed generation

Small-scale reactors have recently attracted attention as a potential power generation source for the future. The Regional Energy Research Institute for Next Generation is currently developing a small-scale reactor called Regional Energy rX 10 MVA (REX-10). The current paper deals with a power system to be used with small-scale reactors for multi-purpose regional energy systems. This small nuclear system can supply electric and thermal energy like a co-generation system. The electrical model of the REX-10 has been developed as a part of the SCADA system. REX-10’s dynamic and electromagnetic performance on the power system is analyzed. Simulations are carried out on a test system based on Ulleung Island’s power system to validate REX-10 availability on a power system. RSCAD/RTDS and PSS/E software tools are used for the simulation.

A Novel Fault Location Scheme on Korean Electric Railway System Using the 9-Conductor Representation

This paper presents a novel fault location scheme on Korean AC electric railway systems. On AC railway system, because of long distance, 40[㎞] or above, between two railway substations, a fault location technique is very important. Since the fault current flows through the catenary system, it must be modeled exactly to analyze the fault current magnitude and fault location. In this paper, suggesting the novel scheme of fault location, a 9-conductor modeling technique including boost wires and impedance bonds is introduced based on the characteristics of Korean AC electric railway. After obtaining a 9-conductor modeling, the railway system is constructed for computer simulation by using PSCAD/EMTDC. By case studies, we can verify superiority of a new fault location scheme and propose a powerful model for fault analysis on electric railway systems.