Jong-Bo Ahn

Development of Hardware In-the-Loop Simulation System for Testing Operation and Control Functions of Microgrid

This paper proposes a hardware in-the-loop simulation (HILS) system as a new method to develop and test control algorithms and operation strategies for a microgrid. The HILS system is composed of a real-time digital simulator (RTDS) for real-time simulation of the microgrid, a prototype microgrid management system (MMS) under test, and a communication emulator for interface between the prototype MMS and the RTDS. The prototype MMS is designed to operate microsources of microgrid and to control power flow at the point of common coupling (PCC) in the grid-connected mode, and voltages and frequency in the islanded mode of the microgrid. The MMS is tested in the grid-connected mode and in the islanded mode, respectively, to show the validation of the proposed HILS system.

Modeling and Control of a Grid-connected Wind/PV Hybrid Generation System

This paper deals with power control of a wind and solar hybrid generation system for interconnection operation with electric distribution system. The proposed system consists of a variable-speed direct-drive wind generator, wind-side converter, solar array, dc-dc converter and grid interface inverter. Power control strategy is to extract the maximum energy available from varying condition of wind speed and solar irradiance while maintaining power quality at a satisfactory level. In order to capture the maximum power, variable speed control is employed for wind turbine and maximum power point tracking is applied for photovoltaic system. The grid interface inverter transfers the energy drawn from the wind turbine and PV array into the grid by keeping common dc voltage constant. Modeling and simulation study on the entire control scheme is carried out using a power system transient analysis tool, PSCAD/EMTDC. The simulation results show the control performance and dynamic behavior of the wind/PV system

Development of Simulator System for Microgrids with Renewable Energy Sources

This paper deals with the design and testing of a simulator system for microgrids with distributed generations. This system is composed of a Real Time Digital Simulator (RTDS) and a power amplifier. The RTDS parts are operated for real time simulation for the microgrid model and the distributed generation source model. The power amplifiers are operated for amplification of the RTDSs simulated output signal, which is a node voltage of the microgrid and distributed generation source. In this paper, we represent an RTDS system design, specification and test results of a power amplifier and simulation results of a PV (Photovoltaic) system and wind turbine system. The proposed system is applicable for development and performance testing of a PCS (Power Conversion System) for renewable energy sources.

Establishment of a pilot plant for KERI microgrid system based on power IT development program in Korea

This paper introduces a microgrid system having been developed in Korea. Firstly, the Korean Power IT (Information Technology)” development program and its environment are shortly described including the concept of Korean microgrid and characteristics of its components. And then, the microgrid system, the functions of its components and test facilities are explained which are established in KERI (Korea Electrotechnology Research Institute). Finally, some system operation results according to two operational modes are shown.

Characteristic analysis of three-phase four-leg inverter based load unbalance compensator for stand-alone microgrid

This paper analyses a three-phase four-leg voltage sourced inverter (VSI) based load unbalance compensator (LUC) including its control algorithm, which is a component of a microgrid. The purpose of proposed three-phase four-leg VSI based LUC is to improve power quality of the stand-alone microgrid. Power quality of the microgrid which was installed in Mara-island, Korea is analysed using a real operational data. In this work, the microgrid in Mara-island which includes a photovoltaic power generation system, a diesel generator, a battery energy storage system, and a power management system is modelled in PSCAD/EMTDC, and proposed three-phase four-leg VSI based LUC is also modelled and applies to the microgrid. Power flow and stability of the modelled microgrid with the LUC is analysed under variable irradiance and unbalance loads. The results show that the proposed LUC helps to improve stability of the stand-alone microgrid. The proposed three-phase four-leg VSI based LUC and its control algorithm can be effectively utilized to the stand alone microgrid which has large unbalance loads.

Digital Signal Processor-Based Power Management System Implementation for a Stand-Alone Microgrid on a Small Island in Korea

This chapter presents a power management system (PMS) for the control of a stand-alone microgrid that was installed in Mara Island’s microgrid system in Korea. Most stand-alone microgrids can control or confine the start, stop, or output of each distributed generator using the energy management system, but these functions cannot guarantee stability against disturbances that occur transiently and unexpectedly due to their reliance on communications. Therefore, Mara Island’s microgrid system developed and applied a PMS that does not rely on communications to secure the stability of the transient system. The PMS controls controllable active and reactive power, particularly that of energy storage systems, for the controllable active power of a diesel engine. First, we performed a controller hardware-in-the-loop simulation to verify the PMS performance. The microgrid system was modeled in a real-time digital simulator, connecting the PMS designed by a digital signal processor. Second, the PMS was installed in Mara Island’s microgrid system in Korea, which includes a photovoltaic power generation system, a diesel engine, a battery energy storage system, and the PMS. These systems are connected to a 380-V, one-feeder distribution subsystem. The loads of the microgrid usually vary from 40 to 120 kW. The results show that the proposed PMS helps to improve the stability of the stand-alone microgrid. The stability and utilization of the system can be increased by utilizing the PMS in accordance with the purpose of the microgrid system.

Comparative Study of Two Types of Wind Turbine Simulators for Wind Energy Conversion System

Electricity generation using wind energy is becoming the fastest growing source of renewable energy. There are several types of wind turbine simulator (WTS) or emulator for evaluation of wind turbine generators, power electronic converters, and turbine control algorithms. These WTSs have each a different purpose, and have been used to serve the purpose.

PMSG Type Wind Power Generation System Connected with EDLC in DC-Link

Wind power generation system (WPGS) is the fasest increasing renewable enerngy source techology nowadays. However, output ppower fluctuation of the WPGS due to variation of wind speed casues a problem of low or some high frequency oscillation in power system. Electric double layer capacitor (EDLC) is used to overcome power quality problem caused by output power oscillation of wind turbines. A new connection scheme of EDLC to WPGS is proposed in which the EDLC is directly connected to DC-link of WPGS with permanent magnet synchronous generator. The structure of the proposed system is cost-effective and efficient. The proposed system including an EDLC is modeled and analyzed by PSCAD/EMTDC. The simulation results show the effectiveness and major features of the proposed system.

Controller-Hardware-In-The Loop Simulation Based Analysis of Photovoltaic Power Generation System under Variable Conditions of Utility

This paper presents a controller-hardware-in-the loop simulation (CHILS) based test system as a controller for testing phtovotaic (PV) power generation system. The analysis of grid-connected PV power generation system to observe the phenomenon and confirm the stability on the PV power generation system under the variable conditions occured in utility was performed. The utility is stable in the steady state but the utility condition can be changed by unexpected phenomenon. The effect of grid condition should be analyzed to make sure the stability of the grid-connected PV power generation system. The PV power generation system is connected to a utility grid through a inverter and several conditions of grid are modeled by using RTDS. A RTDS is employed to calculate the variable conditions of grid. The voltage source inverter (VSI) is controlled by a digital signal processor connected between gigabit transceiver analogue output card and a gigabit transceiver digital input card in the RTDS interface boards. Experiment results are presented and analyzed to show the effect of a variable conditions to the PV system.

Dynamic Battery Modeling for Microgrid Operation

Operating shceme of a battery enenrgy storage system (BESS) is important for reliability and stability of a microgrid. The state of a battery has to be considred for operating scheme decision of the BESS because dynamic performance of the battery depends on state of charge (SOC), electrolyte temeperature, ambient temperature. In this paper, a lead-acid battery is modeled in PSCAD/EMTDC, and operating scheme of BESS is disscuessed. The parameter of battery is identified by using experimental data. The battery model can effectively be employed to model the microgrid for the operation shceme decision.