Editorial

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2 pages, 142 KiB

Open AccessEditorial

Special Issue on State-of-the-Art Renewable Energy in Korea

by Zong Woo Geem, Junhee Hong and Woohyun Hwang

Appl. Sci. 2021, 11(10), 4401; https://doi.org/10.3390/app11104401 - 12 May 2021

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Abstract

Nowadays, renewable energy plays an important role in nationwide power systems [...] Full article

(This article belongs to the Special Issue State-of-the-Art Renewable Energy in Korea)

Research

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14 pages, 3419 KiB

Open AccessArticle

Implementation of a Demand-Side Management Solution for South Korea’s Demand Response Program

by Wonsuk Ko, Hamsakutty Vettikalladi, Seung-Ho Song and Hyeong-Jin Choi

Appl. Sci. 2020, 10(5), 1751; https://doi.org/10.3390/app10051751 - 04 Mar 2020

Cited by 12 | Viewed by 2937

Abstract

In this paper, we show the development of a demand-side management solution (DSMS) for demand response (DR) aggregator and actual demand response operation cases in South Korea. To show an experience, Korea’s demand response market outline, functions of DSMS, real contracted capacity, and [...] Read more.

In this paper, we show the development of a demand-side management solution (DSMS) for demand response (DR) aggregator and actual demand response operation cases in South Korea. To show an experience, Korea’s demand response market outline, functions of DSMS, real contracted capacity, and payment between consumer and load aggregator and DR operation cases are revealed. The DSMS computes the customer baseline load (CBL), relative root mean squared error (RRMSE), and payments of the customers in real time. The case of 10 MW contracted customers shows 108.03% delivery rate and a benefit of 854,900,394 KRW for two years. The results illustrate that an integrated demand-side management solution contributes by participating in a DR market and gives a benefit and satisfaction to the consumer. Full article

(This article belongs to the Special Issue State-of-the-Art Renewable Energy in Korea)

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25 pages, 4911 KiB

Open AccessArticle

Optimal Operational Scheduling of Distribution Network with Microgrid via Bi-Level Optimization Model with Energy Band

by Ho-Young Kim, Mun-Kyeom Kim and Hyung-Joon Kim

Appl. Sci. 2019, 9(20), 4219; https://doi.org/10.3390/app9204219 - 10 Oct 2019

Cited by 12 | Viewed by 2366

Abstract

An optimal operation of new distributed energy resources can significantly advance the performance of power systems, including distribution network (DN). However, increased penetration of renewable energy may negatively affect the system performance under certain conditions. From a system operator perspective, the tie-line control [...] Read more.

An optimal operation of new distributed energy resources can significantly advance the performance of power systems, including distribution network (DN). However, increased penetration of renewable energy may negatively affect the system performance under certain conditions. From a system operator perspective, the tie-line control strategy may aid in overcoming various problems regarding increased renewable penetration. We propose a bi-level optimization model incorporating an energy band operation scheme to ensure cooperation between DN and microgrid (MG). The bi-level formulation for the cooperation problem consists of the cost minimization of the DN and profit maximization of the MG. The goal of the upper-level is to minimize the operating costs of the DN by accounting for feedback information, including the operating costs of the MG and energy band. The lower-level aims to maximize the MG profit, simultaneously satisfying the reliability and economic targets imposed in the scheduling requirements by the DN system operator. The bi-level optimization model is solved using an advanced method based on the modified non-dominated sorting genetic algorithm II. Based on simulation results using a typical MG and an actual power system, we demonstrate the applicability, effectiveness, and validity of the proposed bi-level optimization model. Full article

(This article belongs to the Special Issue State-of-the-Art Renewable Energy in Korea)

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13 pages, 1501 KiB

Open AccessArticle

Assessing the Benefits of Battery Energy Storage Systems for Frequency Regulation, Based on Electricity Market Price Forecasting

by Eunjung Lee and Jinho Kim

Appl. Sci. 2019, 9(10), 2147; https://doi.org/10.3390/app9102147 - 26 May 2019

Cited by 4 | Viewed by 2978

Abstract

In electricity markets, energy storage systems (ESSs) have been widely used to regulate frequency in power system operations. Frequency regulation (F/R) relates to the short-term reserve power used to balance the real-time mismatch of supply and demand. Every alternating current power system has [...] Read more.

In electricity markets, energy storage systems (ESSs) have been widely used to regulate frequency in power system operations. Frequency regulation (F/R) relates to the short-term reserve power used to balance the real-time mismatch of supply and demand. Every alternating current power system has its own unique standard frequency level, and frequency variation occurs whenever there is a mismatch of supply and demand. To cope with frequency variation, generating units—particularly base-loader generators—reduce their power outputs to a certain level, and the reduced generation outputs are used as a generation reserve whenever frequency variation occurs in the power systems. ESSs have recently been implemented as an innovative means of providing the F/R reserve previously provided by base-loader generators, because they are much faster in responding to frequency variation than conventional generators. We assess the economic benefits of ESSs for F/R, based on a new forecast of long-term electricity market price and real power system operation characteristics. For this purpose, we present case studies with respect to the South Korean electricity market as well as simulation results featuring key variables, along with their implications vis-à-vis electricity market operations. Full article

(This article belongs to the Special Issue State-of-the-Art Renewable Energy in Korea)

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15 pages, 1120 KiB

Open AccessArticle

The Effect of a Renewable Energy Certificate Incentive on Mitigating Wind Power Fluctuations: A Case Study of Jeju Island

by Woong Ko, Jaeho Lee and Jinho Kim

Appl. Sci. 2019, 9(8), 1647; https://doi.org/10.3390/app9081647 - 20 Apr 2019

Cited by 8 | Viewed by 2971

Abstract

As renewable energy penetration in power systems grows, adequate energy policies are needed to support the system’s operations with flexible resources and to adopt more sustainable energies. A peak-biased incentive for energy storage systems (ESS) using the Korean renewable portfolio standard could make [...] Read more.

As renewable energy penetration in power systems grows, adequate energy policies are needed to support the system’s operations with flexible resources and to adopt more sustainable energies. A peak-biased incentive for energy storage systems (ESS) using the Korean renewable portfolio standard could make power system operations more difficult. For the first time in the research, this study evaluates the effect of imposing a renewable energy certificate incentive in off-peak periods on mitigating wind power fluctuations. We design a coordinated model of a wind farm with an ESS to model the behavior of wind farm operators. Optimization problems are formulated as mixed integer linear programming problems to test the implementation of revenue models under Korean policy. These models are designed to consider additional incentives for discharging the ESS during off-peak periods. The effects of imposing the incentives on wind power fluctuations are evaluated using the magnitude of the renewable energy certificate (REC) multiplier. Full article

(This article belongs to the Special Issue State-of-the-Art Renewable Energy in Korea)

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11 pages, 2055 KiB

Open AccessFeature PaperCommunication

Optimal Design of a Residential Photovoltaic Renewable System in South Korea

by Hyunkyung Shin and Zong Woo Geem

Appl. Sci. 2019, 9(6), 1138; https://doi.org/10.3390/app9061138 - 18 Mar 2019

Cited by 13 | Viewed by 2441

Abstract

An optimal design model for residential photovoltaic (PV) systems in South Korea was proposed. In the optimization formulation, the objective function is composed of three costs, including the monthly electricity bill, the PV system construction cost (including the government’s subsidy), and the PV [...] Read more.

An optimal design model for residential photovoltaic (PV) systems in South Korea was proposed. In the optimization formulation, the objective function is composed of three costs, including the monthly electricity bill, the PV system construction cost (including the government’s subsidy), and the PV system maintenance cost. Here, because the monthly electricity bill is not differentiable (it is a stepped piecewise linear function), it cannot be solved by using traditional gradient-based approaches. For details considering the residential electric consumption in a typical Korean household, consumption was broken down into four types (year-round electric appliances, seasonal electric appliances, lighting appliances, and stand-by power). For details considering the degree of PV generation, a monthly generation dataset with different PV tilt angles was analyzed. The optimal design model was able to obtain a global design solution (PV tilt angle and PV size) without being trapped in local optima. We hope that this kind of practical approach will be more frequently applied to real-world designs in residential PV systems in South Korea and other countries. Full article

(This article belongs to the Special Issue State-of-the-Art Renewable Energy in Korea)

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11 pages, 1919 KiB

Open AccessArticle

Designing a Waterless Toilet Prototype for Reusable Energy Using a User-Centered Approach and Interviews

by Hyun-Kyung Lee

Appl. Sci. 2019, 9(5), 919; https://doi.org/10.3390/app9050919 - 04 Mar 2019

Cited by 6 | Viewed by 4100

Abstract

User-oriented community engagement can reveal insights into ways of improving a community and solving complex public issues, such as natural resource scarcity. This study describes the early process of co-designing a novel, waterless toilet to respond to the water scarcity problem in the [...] Read more.

User-oriented community engagement can reveal insights into ways of improving a community and solving complex public issues, such as natural resource scarcity. This study describes the early process of co-designing a novel, waterless toilet to respond to the water scarcity problem in the Republic of Korea. It presents how we designed a toilet focusing on three factors—a sanitization function, an ergonomic posture, and clean aesthetics—by conducting focus group interviews as part of a user engagement approach to understand what community users want from a toilet and ways of improving their toilet experiences. The results not only supported the development of an experiential service design project to raise community awareness of water scarcity but also supported scientists and engineers in experimenting with and developing new technologies by collaborating closely with designers. Full article

(This article belongs to the Special Issue State-of-the-Art Renewable Energy in Korea)

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8 pages, 1653 KiB

Open AccessArticle

Eco-Friendly Education Facilities: The Case of a Public Education Building in South Korea

by Eunil Park and Angel P. Del Pobil

Appl. Sci. 2018, 8(10), 1733; https://doi.org/10.3390/app8101733 - 25 Sep 2018

Cited by 3 | Viewed by 3121

Abstract

Since the importance and effects of national energy policies, plans, and roadmaps were presented in South Korea, the role of renewable energy resources has received great attention. Moreover, as there is significant reasoning for reducing and minimizing nuclear and fossil fuel usage in [...] Read more.

Since the importance and effects of national energy policies, plans, and roadmaps were presented in South Korea, the role of renewable energy resources has received great attention. Moreover, as there is significant reasoning for reducing and minimizing nuclear and fossil fuel usage in South Korean national energy plans, several academic scholars and implementers have expended significant effort to present the potential and feasibility of renewable energy resources in South Korea. This study contributes to these efforts by presenting potential sustainable configurations of renewable energy production facilities for a public building in South Korea. Based on economic, environmental, and technical information as well as the presented simulation results, it proposes an environmentally friendly renewable energy production facility configuration that consists of photovoltaic arrays, battery units, and a converter. Subsidies for installing and renovating such facilities are also considered. The potential configuration indicates $0.464 as the cost of energy, 100% of which is renewable. Potential limitations and future research areas are suggested based on the results of these simulations. Full article

(This article belongs to the Special Issue State-of-the-Art Renewable Energy in Korea)

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22 pages, 4606 KiB

Open AccessArticle

An Optimized Protection Coordination Scheme for the Optimal Coordination of Overcurrent Relays Using a Nature-Inspired Root Tree Algorithm

by Abdul Wadood, Saeid Gholami Farkoush, Tahir Khurshaid, Chang-Hwan Kim, Jiangtao Yu, Zong Woo Geem and Sang-Bong Rhee

Appl. Sci. 2018, 8(9), 1664; https://doi.org/10.3390/app8091664 - 15 Sep 2018

Cited by 54 | Viewed by 4013

Abstract

In electrical engineering problems, bio- and nature-inspired optimization techniques are valuable ways to minimize or maximize an objective function. We use the root tree algorithm (RTO), inspired by the random movement of roots, to search for the global optimum, in order to best [...] Read more.

In electrical engineering problems, bio- and nature-inspired optimization techniques are valuable ways to minimize or maximize an objective function. We use the root tree algorithm (RTO), inspired by the random movement of roots, to search for the global optimum, in order to best solve the problem of overcurrent relays (OCRs). It is a complex and highly linear constrained optimization problem. In this problem, we have one type of design variable, time multiplier settings (TMSs), for each relay in the circuit. The objective function is to minimize the total operating time of all the primary relays to avoid excessive interruptions. In this paper, three case studies have been considered. From the simulation results, it has been observed that the RTO with certain parameter settings operates better compared to the other up-to-date algorithms. Full article

(This article belongs to the Special Issue State-of-the-Art Renewable Energy in Korea)

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