• Journal of IKEEE
• /
• v.23 no.3
• /
• pp.826-831
• /
• 2019

The stand-alone photovoltaic power systems are widely used for lighting equipment and CCTV. In order for these devices to be competitive, the life of power storage devices such as batteries is very important. The characteristic Hybrid supercapacitor is the high power density and long life. We have proposed a stand-alone photovoltaic power system that uses hybrid supercapacitor. The charge and discharge characteristics and the internal resistance of the hybrid capacitor were measured to configure the power converter. A stable maximum output point tracking control algorithm is proposed even with the change in solar radiation. In order to verify the validity of the proposed system, a prototype was fabricated and tested using a 18W hybrid capacitor and a 10W solar cell.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.10 no.2
• /
• pp.247-252
• /
• 2015

The majority of electric power in the domestic manned islands with off-grid power system is supplied by the diesel generators. However, in the case of off-grid islands the fuel cost is more expensive to inland areas and difficult to transport them to islands. So the development of renewable energy system using natural resource have been recently introduced. But renewable energy that depend on the natural environment, it is necessary to organized the hybrid system with existing diesel engine because the energy is difficult to maintain stable electric power. This paper presents the results of a feasibility study of hybrid system with energy storage system such as wind, solar, battery and diesel engine. The study included off-grid island as the Seogeochado islands located in Jeolanamdo Province. And, the paper proposed a optimal capacity of hybrid system configuration to maintain carbon free with minimum investment cost. the analysis of economic adaptability performed by HOMER program.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.30 no.3
• /
• pp.79-85
• /
• 2016

This paper analyzed the influence of wind power fluctuations in grid frequency of a stand-alone microgrid that is hybrid generation system with diesel generator, wind turbine, and Battery Energy Storage System (BESS). The existing island area power system consists of only diesel generators. So the grid frequency can be controllable from load change. But hybrid generation system with Renewable Energy Sources (RES) such as wind energy that has the intermittent output can bring power quality problems. BESS is one of the ways to improve the intermittent output of the RES. In this paper, we analyzed the role of BESS in a stand-alone microgrid. We designed a modelling of wind power system with squirrel-cage induction generator, diesel power system with synchronous generator, and BESS using transient analysis program PSCAD/EMTDC. And we analyzed the variation of the grid frequency according to the output of BESS.

• 한국신재생에너지학회:학술대회논문집
• /
• 2005.06a
• /
• pp.361-365
• /
• 2005

Since the fuel cell uses the hydrogen for its fuel. it has no emission and higher efficiency than an internal combustion engine. Also fuel cell is much quieter than engine generator and generates heat much less than engine generator. So it has advantage of Army's 'si lent watch' capability and the ability to operate undetected by the enemy. The fuel cell hybrid system combines a fuel cell power system with an ESS. The ESS (e.g., batteries or ultracapacitors) reduces the fuel cell's peak power and transient response requirements. It allows the fuel cell to operate more efficiently and recovery of vehicle energy during deceleration. The battery has high energy density, so it has the advantage regarding driving distance. However, it has a disadvantage considering dynamic characteristic because of low power density. One other hand. the ultracapacitor has higher power density, so it can handle sudden change or discharge of required power. Yet. it has lower energy density. so it will be bigger and heavier than the battery when it has the same energy. This paper proposes the power management strategy for multi-power source fuel cell hybrid system. which is applied with the merits of both battery and ultra capacitor by using both of them simultaneous.

• Progress in Superconductivity
• /
• v.13 no.3
• /
• pp.195-202
• /
• 2012

In this paper, we designed Active Magnetic Bearing (AMB) for large scale Superconductor Flywheel Energy Storage System (SFESS) and PD controller for AMB. And we experimentally evaluated SFESS including hybrid type AMB. The radial AMB was designed to provide force slew rate that was sufficient for the unbalance disturbances at the maximum operating speed. The thrust AMB is a hybrid type where a permanent magnet carries the weight of the flywheel and an electromagnetic actuator generates the dynamic control force. We evaluated the design performance of the manufactured AMB through comparison of FEM analysis and the results of experimental force measurement. In order to obtain gains of PD controller and design a notch filter, the system identification was performed through measuring frequency response including dynamics for the AMBs, a power amp and a sensor using a sine swept test method after levitating the flywheel. Through measuring the current input of the AMBs and the orbit of a flywheel according to rotational speed, we verified excellent control performance of the AMBs with small amount current for the large scale SFESS.

• Journal of Power Electronics
• /
• v.8 no.4
• /
• pp.291-300
• /
• 2008

In this paper power system and drive-train for omni-directional autonomous mobile robots with multiple energy storage units are presented. Because in proposed system, which is implemented in soccer robots, the ability of power flow control from of multiple separated energy storage units and speed control for each motor are combined, these robots can be derived by more than one power source. This capability, allow robot to diversify its energy source by employing hybrid power sources. In this research Lithium ion polymer batteries have been used for main and auxiliary energy storage units because of their high power and energy densities. And to protect them against deep discharge, over current and short circuit, a protection circuit was designed. The other parts of our robot power system are DC-DC converters and kicker circuit. The simulation and experimental results show proposed scheme and extracted equations are valid and energy management and speed control can be achieved properly using this method. The filed experiments show robot mobility functions to perform the requested motion is enough and it has a high maneuverability in the field.

• Proceedings of the KIPE Conference
• /
• 2013.07a
• /
• pp.467-468
• /
• 2013

In this paper, a switching control strategy of bidirectional converter for energy storage system in photovoltaic hybrid modules is proposed. The bidirectional converter for energy storage system (ESS) with battery is connected with DC link in parallel which is located between current source flyback converters(CSFC) and unfolding bridge. Because CSFC generates rectified sinusoidal current, the bidirectional converter requires suitable control strategy. Therefore, a theoretical analysis of the proposed switching control strategy is presented. And, validity is confirmed through simulation results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.26 no.4
• /
• pp.48-56
• /
• 2012

The object of this paper is the controller for supplying stably power in a separate house in which a hybrid electrical storage system with a stand-alone photovoltaic/wind power generation system and a small generator is applied. In the photovoltaic/wind hybrid power system used in the separate house, when only the battery is used in sunless days, the capacity of the battery is become larger. In particular, as in recent days, if cloudy days are frequent due to anomaly climate, it is difficult to estimate the number of sunless days. Accordingly, it is preferable to build the electrical storage system that numbers of sunshineless days are to be controlled and a shortage amount of the power generation capacity is to be handled by a small generator system. In order to supply stably power of new renewable energy such as solar to any separate houses, it is preferable to reduce the capacity of battery by decreasing the number of sunless days when estimating the capacity of battery and to drive the small generator for compensation of the power shortage. Such system needs components including inverters for photovoltaic and wind power generation system, batteries and controllers for automatically driving the small generator, based upon the nature of the stand-alone house, and it is preferable to use the controller having a simpler and higher stability by adopting the all-in-one scheme to facilitate its maintenance.

• Proceedings of the KIPE Conference
• /
• 2012.11a
• /
• pp.147-148
• /
• 2012

Recently, hybrid generation systems combine multiple energy sources or storage components to optimize the characteristics of the individual energy sources. In this paper, a battery integrated PV power optimizer for PV-battery hybrid power generation system is proposed. PV system using proposed topology can easily increase battery capacity and remove high power bidirectional converter to control bulky battery bank.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.30 no.8 s.251
• /
• pp.756-763
• /
• 2006

PEMFC has several technical problems such as water management, long term stability and performance degradation as. PEMFC has been studied not only to solve water management, but also to generate power in stable manner to system by using a hybrid system with auxiliary energy storage device. The purpose of this study is to couple PEMFC with supercapacitor to make a hybrid system and to design and test control strategies for stable power generation in case of changing output power. The polarization curve and dynamic behaviors while changing power were investigated to find out characteristics of PEMFC stack. A DC/DC converter was fabricated in order to increase fuel cell and supercapacitor voltage and to charge supercapacitor. We found that the operation strategy 2 was recommended to the system because of solving water management problem and increasing the dynamic behavior.