Minwon Park

A novel real-time simulation technique of photovoltaic generation systems using RTDS

For the performance test of photovoltaic (PV) generation systems, actual system apparatuses: a solar panel, converter system, and load facilities should be installed. It is also hardly possible to compare a maximum power point tracking (MPPT) control scheme with others under the same weather and load conditions in an actual PV generation system. One of the possible alternatives is to realize a transient simulation scheme for PV generation systems under real weather conditions of insolation and surface temperature of solar cell. The authors propose a novel real-time simulation method for PV generation systems under real weather conditions using a real-time digital simulator (RTDS). V--I curves of a real PV panel are tested using electric load device, and a hypothetical network of the tested PV panel is created on the RTDS by arranging electrical components from the customized component model libraries. The real weather conditions, insolation, and temperature of the PV panel, are interfaced through the analog input ports of the RTDS for real-time simulation. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation technique, and also show that cost-effective verification of availability and stability of PV generation systems is possible using the built-in simulator.

A novel simulation technique of the PV generation system using real weather conditions

The photovoltaic (PV) generation system has been studied and watched with keen interest as a clean energy source. Moreover, the various MPPT control methods are proposed to more efficient utilized. Now, in order to confirm the effectiveness of each control method, simulation or experimental analysis is used. Here, from an economical point of view, simulation analysis is more effective. However, the more detailed model of a solar cell for simulation is necessary. In this paper, a novel simulation analysis method of the PV generation system with VI characteristics equation of a solar cell and real weather condition is proposed. Here, ATP is used as the simulation analysis software. We compared the results from the simulation analysis with the experimental one. Consequently, two values were very matched and the validity of the proposed method is examined. The result shows that the cost effective verification for the efficiency, availability and stability of the PV generation systems. The comparison research of various control methods like MPPT control under the same weather conditions is possible.

A maximum power point tracking for photovoltaic-SPE system using a maximum current controller

Abstract Processes to produce hydrogen from solar photovoltaic (PV)-powered water electrolysis using solid polymer electrolysis (SPE) are reported. An alternative control of maximum power point tracking (MPPT) in the PV-SPE system based on the maximum current searching methods has been designed and implemented. Based on the characteristics of voltage–current and theoretical analysis of SPE, it can be shown that the tracking of the maximum current output of DC–DC converter in SPE side will track the MPPT of photovoltaic panel simultaneously. This method uses a proportional integrator controller to control the duty factor of DC–DC converter with pulse-width modulator (PWM). The MPPT performance and hydrogen production performance of this method have been evaluated and discussed based on the results of the experiment.

A novel simulation method for PV power generation systems using real weather conditions

In PV power generation systems, huge system apparatus are needed in order to verify the effect of system efficiency and stability considering the size of solar panel, the sort of converter and the load condition. Also, under the same weather and load conditions, it is almost impossible to compare a certain MPPT control scheme with another. In order to remedy the above, one must realize the transient simulation of PV power systems using real field weather conditions. In this paper, the authors introduce how to apply real field weather conditions to EMTP and EMTDC, which are the most generalized transient analysis simulators. First of all, a solar cell is simulated with a V-I characteristic equation of the solar cell, and real field data of weather conditions are interfaced to EMTP and EMTDC programs using a Fortran program interface method. As a result, comparing real data of a PV panel and the simulated data, the authors obtained hopeful answers and made the simulation of PV power generation system much closer to reality. As a merit of using this proposed simulation method, stability and efficiency analyses according to various MPPT controls are possible under the same weather conditions.

A novel MPPT control method using optimal voltage of PV with secondary phase-shift PWM control DC-AC converter

In this paper, a novel maximum power point tracking (MPPT) scheme is proposed and simulated using a high-frequency AC link converter with a secondary side PWM control scheme. Considering that the optimal voltage point of a solar cell is proportional to its panel temperature, with operating a power converter whose operating point keeps its input voltage at the maximum power point, the maximum power point becomes tentatively possible to be tracked. As a result, the authors obtained a hopeful application to the practical field; furthermore the secondary phase-shift PWM control DC-AC converter showed a special quality to application to solar generation systems.

Simulation Analysis of Microgrid Using Real Time Digital Simulator

Microgrid is a new type of electric power grid which consists of distributed generation systems, energy storage devices and loads. It can operate either in grid-connected or islanded operation mode. Due to environmental pressure and enhanced demands on quality, security and reliability of electric power energy system, a microgrid has become a subject of special interest. In this paper, microgrid which has permanent magnet synchronous generator type wind power generation system, photovoltaic power genetation system, diesel generator, battery energy storage system (BESS), energy storage system (ESS) with an electric double layer capacitor (EDLC) and load was modeled using real time digital simulator. The modeled microgrid was simulated in both grid-connected and islanded operation mode. Simulation results represent that microgrid can supply high quality electric power to customers through the operation BESS and ESS with an EDLC. The modeled microgrid can be utilized to develop management system for a microgrid.

Design of conduction cooling system for a high current HTS DC reactor

A DC reactor using a high temperature superconducting (HTS) magnet reduces the reactors size, weight, flux leakage, and electrical losses. An HTS magnet needs cryogenic cooling to achieve and maintain its superconducting state. There are two methods for doing this: one is pool boiling and the other is conduction cooling. The conduction cooling method is more effective than the pool boiling method in terms of smaller size and lighter weight. This paper discusses a design of conduction cooling system for a high current, high temperature superconducting DC reactor. Dimensions of the conduction cooling system parts including HTS magnets, bobbin structures, current leads, support bars, and thermal exchangers were calculated and drawn using a 3D CAD program. A finite element method model was built for determining the optimal design parameters and analyzing the thermo-mechanical characteristics. The operating current and inductance of the reactor magnet were 1,500 A, 400 mH, respectively. The thermal load of the HTS DC reactor was analyzed for determining the cooling capacity of the cryo-cooler. The study results can be effectively utilized for the design and fabrication of a commercial HTS DC reactor.

PHLIS-Based Characteristics Analysis of a 2 MW Class Tidal Current Power Generation System

In this paper, characteristics of a tidal current power generation system are analysis using power hardware-in-the-loop simulation (PHILS). A 10 kW motor generator set is connected to the real grid through a fabricated 10 kW back to back converter. A power control scheme is applied to the back to back converter. A 2 MW class tidal current turbine is modeled in real time digital simulator (RTDS). Generating voltage and current from the 10 kW PMSG is applied to a 2 MW class tidal current turbine in the RTDS using PHILS. The PHILS results depict the rotation speed, power coefficient, pitch angle, tip-speed ratio, and output power of tidal current turbine. The PHILS results in this paper can contribute to the increasing reliability and stability of the tidal current turbines connected to the grid using PHILS.

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.