Jung-Sung Park

Microgrid village design with renewable energy resources and its economic feasibility evaluation

The concept of microgrid village design with the distributed energy resources and its economic feasibility evaluation are depicted in this paper. The engineering flow is comprised of four parts such as natural environment and demand analysis, selection of applicable distributed energy resources and electrical network design, power network analysis, and its economic evaluation. In order to show the effectiveness of the proposed methodology, Changwon Dongjeun village in Kyoungnam province is taken as a test case that has seven districts consisting of single-family houses, commercial buildings, apartment buildings and a public park.

Frequency Control Method of Grid Interconnected Microgrid Operating in Stand Alone Mode

Microgrid is a new electrical energy system that composed of various generators, renewable energy, batteries and loads located near the electrical customers. When Microgrid is interconnected with large power system, Microgrid don`t need to control the frequency. But in case of the outage or faults of power system, Microgrid should control the frequency to prevent the shutdown of Microgrid. This paper presents the frequency control methods using the droop function, being used by synchronous generators and EMS(Energy Management System). Using droop function, two battery systems could share the load based on locally measured signals without any communications between batteries. Also, we suggest that EMS should control the controllable distributed generators as P/Q control modes except batteries to overcome the weakness of droop function. Finally we suggest the two batteries systems to prolong the battery`s life time considering the economical view. The validation of proposed methods is tested using PSCAD/EMTDC simulations and field test sites at the same time.

Automatic Generation Control System for Operation Mode in Microgrid

The microgrid concept assumes a cluster of loads and microsources operating as a single controllable system that provides a new paradigm for defining the operation of distributed generation. This system can be operated as both grid-connected mode and islanded mode. In other words, the microgrid can be operated to meet their special need; such as economics in steady state and local reliability in islanded mode due to the grid fault. This paper presents the AGC (Automatic Generation Control) method for microgrid with EMS (Energy Management System).

Functional Properties of Stand-alone Microgrid EMS Application

For many past years, research in the operation of stand-alone Microgrid, which provides electric power generated from renewable energy sources and energy storage system instead of diesel generators, has been a major issue in order to prepare the exhaustion of fossil fuel and to protect environment, in island grids. Samso Island, known as the world’s first stand-alone Microgrid in Denmark, is connected to the mainland grid through AC system, which has different technical conditions with Korea’s isolated power system. Korea’s first stand-alone Microgrid has been built in Ga-sa island, Chun-la-nam-do, based on Energy Management System (EMS) operation, and other islands are under construction to follow the next step. These stand-alone Microgrid’s has large capacity of Battery Energy Storage System (BESS) and the proportion of the renewable energy sources are large, which makes it necessary to use a Microgrid-Energy Management System (MG-EMS) to operate the grid effectively and economically. However, since the main subject of MG-EMS is different from EMS, specific characteristics and functions must be different as well. In this paper, the necessary characteristics and functions are explained for a general MG-EMS compared to a large power system EMS.

A Study on the Limit Analysis of the LED Lighting Subsidy Program Considering the Perspective of Individual Building Clients

Various DSM (Demand Side Management) programs have been developed and carried out to use the limited energy resources of human-beings reasonably. LED lighting is one of essential DSM programs and the development of technologies is ongoing vigorously. Recently, one-person households have been increased and the electricity consumption pattern is different with conventional households because residents live as a single. On the other hand, owners of the one-person households tend to not prefer to install high efficient appliances due to the cost increasement. Therefore, the existing DSM subsidy programs should be revaluated so that the owners decide to install high efficient appliances.

A Study on Optimal Planning of Microgrid with Actual Loading

AbstractMicroGrids are small power supply system located on-site that can supply both the electricity and the hot-water simultaneously. MicroGrid system that consists of Distributed Energy Resources system, such as wind, solar, fuel-cell and co-generation, has been developed greatly during the last 10 years. Its concept assumes a cluster of loads and microsources operating as a single controllable system that provides a new paradigm for defining the operation of distributed generation. For example this cell could be controlled as a single dispatchable load, which can respond in seconds to meet the needs of the transmission system. It can be also designed to meet their special need; such as, enhance local reliability, reduce feeder losses. This paper introduces the case study of engineering to construct Microgrid with actual loading in KEPRI

Frequency Control of Battery Energy Storage System with a Deadband and Restoration Control in Microgrid

The grid-interconnected microgrid can be able to operate with and without the utility microgrid to supply electricity. when the microgrid operates in grid-connected mode, the frequency of the microgrid synchronizes with the system frequency. In this case, the frequency of the microgrid has small variation which is able to change the output of distributed generation with a droop controller. Thus, the small variation of frequency can make the distributed generation generate unnecessary electricity consistently. In this paper, we propose a frequency droop control with a dead band so as to prevent the distributed generations from generating unnecessary output while in grid-interconnected mode. In addition, a distributed generation can have a restoration control to restore the frequency changed by a droop control as a rated frequency. Also, we state the problem of restoration control with a dead band, and propose its solution when the microgrid operates in stand alone mode. We simulate the proposed droop control using PSCAD/EMTDC to verify the validity of the control.

The Development and Experimental Evaluation of 100kVA Unified Power Quality Conditioner interconnected to the Li-Battery System

This paper propose the advanced topology of UPQC, its DC link is connected with Lithium battery, to compensate the momentary interruptions. The proposed system can be operated as UPS mode using the parallel inverter, which control the charge or discharge of battery, in case of the interruption. We dvelop 100kVA UPQC using the proposed topology to rise the power quality and the reliability of Microgrid. We verify its usefulness through voltage compensation test, UPS operation test and etc. using Microgrid test facility.

An Improvement of Optical Fiber Composite Power Cable On-Line Monitoring System for Underground Distribution Network

Since power system is switching to smart grid, on-line monitoring technology has become necessary for underground distribution power cable. Therefore, the application of DTS(Distributed Temperature Sensing) technology using OFCPC(Optical Fiber Composite Power Cable) capable of monitoring underground distribution power cables has been developed. These can bring about reductions in faults and increases in operating capacity of underground distribution system. To date, the test-bed of optical fiber composite power cable on-line monitoring system has been constructed. Then, matters to be improved have been drawn through verification experiments. This paper presents the improvement and experiment results of the optical fiber composite power cable on-line monitoring system to apply to underground distribution lines in the field.

The Development & Performance Test of 10[kW] Power Conditioning System for Microgrid

PCS(Power Conditioning System) is the necessary component in Microgrid, composed of multiple distributed generators and energy storage system. In this paper, the functions of PCS are defined and 10[kW] PCS for PV and BESS are developed. To apply PCSs to Microgrid, this paper presents a 3-phase inverter with the decoupling current controller, voltage controller and DPLL control system. PCSs were applied to 120[kW] pilot plant and its performance tests were carried out. Test results of PCS at each operation mode show stable in Microgrid.