• Proceedings of the Korea Information Processing Society Conference
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• 2017.11a
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• pp.1241-1243
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• 2017

As the era of the fourth industrial revolution, renewable energy has been highlighted instead of fossil energy resource. Solar energy is constantly being developed in renewable energy, but energy gathering methods are not yet effective. In this paper, we study an efficient monitoring module for photovoltaic system for better performance of light sensor based solar tracking photovoltaic system with real time manner.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.143-145
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• 2005

There has been increasing interest in the renewable energies. Wind energy is worldwide number one renewable energy from the installed capacity viewpoint. Most of the power systems utilizing wind energy are connected to other large systems. In such integrated systems, frequency control is not big issue. Rut the situation is different in isolated systems like Korean power system. It is important to assess appropriate capacity of wind power for our system, as it affects the system operation and control strategy. In this paper we made it clear the relationship among generator inertias, governor droop, system damping and wind energy capacity.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.361-366
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• 2013

This paper presents the effect on application of the flywheel energy storage system (FESS) for load frequency control (LFC) of an interconnected 2 area power system. To do this, the control characteristics with the FESS were compared with that of the conventional governor controller. The controller for the FESS control and the governor control used a PID type controller. Both the FESS PID controller and the governor PID controller using genetic algorithm (GA) were designed to optimize the PID parameters. The frequency and generation output characteristics with the only FESS controller and with the only conventional governor controller were compared. To verify robust performance of the FESS controller, the computer simulations were performed under various disturbances. The simulation results showed that the FESS controller provided better dynamic responses in comparison with the conventional governor controller.

• Journal of Energy Engineering
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• v.25 no.4
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• pp.110-123
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• 2016

Since increase in energy consumption and environmental issues started to grab global attention, various countries have had their own supporting policy to promote supply of renewable energy which is a stable and eco-friendly energy source. This study analyses Korean Renewable Portfolio Standard by comparative analysis of current policies in major countries in respect of design components of a pragmatic industrial policy system, such as political leadership, policy coordination and consultative committee discussion, and policy enforcement with responsibility and transparency. This is to identify problems and to present political suggestions for successful management of the standard based on a fundamental concept of the pragmatism industrial policy. It is predicted that the strategic cooperation between a market and a government leads to industry development as the relationships of two parties are regarded not as antagonistic but as complementary.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.6
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• pp.1046-1052
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• 2010

In residential house, photovoltaic (PV) system among various alternatives in renewable energy system is the most efficient and feasible solution for reducing energy consumption and electricity cost. However, relatively high initial cost make people reluctant to install PV system in their houses. Therefore, in the initial state for PV system installation in the house, it is very important to decide proper capacity of the PV system considering the expected energy usage and solar energy supplying condition with the house. This paper proposes a novel optimization model for deciding appropriate capacity of the PV system for residential house. The objective function of the model is to minimize the annual cost including electricity bill, operation and maintenance cost, and annual fixed cost calculated from the initial installation cost based on capital recovery factor (CRF). The model also shows the optimal inclining angle of PV panels of the system. In this paper, we estimate the PV output using PVWATTS (PV simulator of Office of Energy Efficiency and Renewable Energy) and find optimal solutions by Sequential Quadratic Programming (SQP) method using MATLAB software. The proposed approach is finally applied to a residential model house in Gangneung, Gangwon-Do and verified its feasibility for adopting to PV system design for residential houses.

• Journal of Power System Engineering
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• v.11 no.4
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• pp.32-37
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• 2007

Regarding the need of energy in advance and the depletion of fossil fuel energy, all researches around the world now are trying to extract energy from many alternative sources especially the renewable one. Solar, ocean tidal, wind and geothermal energy are renewable energy fields which many researches are focused on. This paper explains about effort to replace electric pump used in solar water heating system by bubble pump. The utilization of bubble pump in this system is very efficient since it needs heat energy for its operation that can be obtained easily. In addition, it can also simplify the construction of the system. Bubble pump also functions as a controller to circulate water inside the system. Before the installation of bubble pump, the special quality and performance of bubble pump should be analyzed. The result got from the analysis could show the fluctuation of water flow rate occurred because it sensitively reacts to the heat quantity. Here the heat quantity is taken from the solar that, as we know, is not stable in a whole day. Problems often occurred are the flow rate in this system is very low moreover it could be stop if the pressure exceeds the limit.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.73-76
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• 2009

Generally, wind or solar power system is operated as a stand-alone power system, the efficiency of which could be higher by designing wind-solar combined system considering average wind speed and solar radiation of the desert region, Mongolia. This system is designed to generate electricity for power users and pumps the ground water for irrigation using deep well pump. The ground water can be used for farming or forestation where there is no or little irrigation system. In connection with this study, a renewable energy park, Green Eco Energy Park, was developed at about 50km east of Ulaanbaatar. 3 sets of 10kW wind power generator and 70 kW of solar power module were installed there. The electricity generated from the system is used to on-site office building and deep well pump for ground water pumping. A 10kW stand-alone solar pumping system, which has no rechargeable battery system, is installed to pump the ground water with the amount of generated power. The ground water is stored in 3 artificial ponds and then it is used for raising nursery tree and farming. The purpose of this study is to provide a possible energy solution to desert regions where there is no or little power system. The system also supply power to ground water pump, and the water can be used for farming and forestation, which will also be a solution of preventing desertification or spreading of desert area.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.165-175
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• 2015

Energy storage system has been widely applied in power distribution sectors as well as in renewable energy sources to ensure uninterruptible power supply. This paper presents a model predictive algorithm to control a bidirectional AC-DC converter, which is used in an energy storage system for power transferring between the three-phase AC voltage supply and energy storage devices. This model predictive control (MPC) algorithm utilizes the discrete behavior of the converter and predicts the future variables of the system by defining cost functions for all possible switching states. Subsequently, the switching state that corresponds to the minimum cost function is selected for the next sampling period for firing the switches of the AC-DC converter. The proposed model predictive control scheme of the AC-DC converter allows bidirectional power flow with instantaneous mode change capability and fast dynamic response. The performance of the MPC controlled bidirectional AC-DC converter is simulated with MATLAB/Simulink(R) and further verified with 3.0kW experimental prototypes. Both the simulation and experimental results show that, the AC-DC converter is operated with unity power factor, acceptable THD (3.3% during rectifier mode and 3.5% during inverter mode) level of AC current and very low DC voltage ripple. Moreover, an efficiency comparison is performed between the proposed MPC and conventional VOC-based PWM controller of the bidirectional AC-DC converter which ensures the effectiveness of MPC controller.

• Journal of Energy Engineering
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• v.24 no.2
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• pp.45-50
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• 2015

In Korea ranking sixth out of The world's greenhouse gas emissions, all Korean public buildings have to implement obligatorily renewable energy systems for energy production to reduce the greenhouse gas emissions from the energy consumed in operation, maintenance and management of buildings. The optimum combination and application rates for each energy source emerge from analyzing the trend of previous studies and the energy consumption is simulated by using a dynamic energy simulation program and the initial investment costs, the energy costs, the maintenance costs, the replacement costs emerge based on the calculated result. The result show that the total life cycle cost of 100% gerthermal is the lowest with \ 2,105,974,344 on the analysis results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.4
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• pp.505-514
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• 2015

This paper proposes a probabilistic generation assessment model of renewable energy generators(REGs) considering uncertainty of resources, mainly focused on Wind Turbine Generator(WTG) and Solar Cell Generator(SCG) which are dispersed widely in South Korea The proposed numerical analysis method assesses the one day-ahead generation by combining equivalent generation characteristics function and probabilistic distribution function of wind speed(WS) and solar radiation(SR) resources. The equivalent generation functions(EGFs) of the wind and solar farms are established by grouping a lot of the farms appropriately centered on Weather Measurement Station(WMS). First, the EGFs are assessed by using regression analysis method based on typical least square method from the recorded actual generation data and historical resources(WS and SR). Second, the generation of the REGs is assessed by adding the one day-ahead resources forecast, announced by WMS, to the EGFs which are formulated as third order degree polynomials using the regression analysis. Third, a Renewable Energy Generation Assessment System(REGAS) including D/B of recorded actual generation data and historical resources is developed using the model and algorithm predicting one day-ahead power output of renewable energy generators.