Real-Time Dynamic Simulation of Korean Power Grid for Frequency Regulation Control by MW Battery Energy Storage System

The aim of this study was to develop a real-time dynamic simulator of a power grid with power plant and battery model. The simulator was used to investigate the frequency control characteristics of a megawatt-scale high-capacity energy storage system connected to the electric power grid. In this study, a lithium-ion secondary battery was chosen as one of the batteries for a grid-connected model. The dynamics of the model was analysed in both steady and transient states. The frequency control system of the battery model plays a role in regulating the grid frequency by controlling the power of energy storage systems according to process variables and grid frequencies. The power grid model based on the current power network of South Korea, included power plants, substations and power demands. The power supply is classified by the type of turbine generator as thermal, nuclear, hydro power, pumped power storage, combined power plants and batteries, including high-capacity energy storage systems rated for a maximum of 500 MW. This study deals with an installed capacity of 87.17 GW and peak load of 77.30 GW in the Korean power grid. For 24 hours of operation, the maximum and minimum power outputs were simulated as 61.59 GW and 46.32 GW, respectively. The commercialized real-time dynamic simulation software ProTRAX was used. The simulation was conducted to observe the operation characteristics of the frequency control system during a breakdown of power plants, as well as under governor-free operation, auto generation control operation, and with the battery energy storage system connected. The results show that the model is valid for each power plant breakdown simulation. They also confirm that the output power and frequency controls of the battery operated well during simulations

Review of virtual power plant applications for power system management and vehicle-to-grid market development

The use of renewable energy sources and energy storage systems is increasing due to new policies in the energy industries. However, the increase in distributed generation hinders the reliability of power systems. In order to stabilize power systems, a virtual power plant has been proposed as a novel power grid management system. The virtual power plant plays includes different distributed energy resources and energy storage systems. We define a core virtual power plant technology related to demand response and ancillary service for the cases of Korea, America, and Europe. We also suggest applications of the proposed virtual power plant to the vehicle-to-grid market for restructuring national power industries in Korea

Human Comfort-Based-Home Energy Management for Demand Response Participation

The residential building sector is encouraged to participate in demand response (DR) programs owing to its flexible and effective energy resources during peak hours with the help of a home energy management system (HEMS). Although the HEMS contributes to reducing energy consumption of the building and the participation of occupants in energy saving programs, unwanted interruptions and strict guidance from the system cause inconvenience to the occupants further leading to their limited participation in the DR programs. This paper presents a human comfort-based control approach for home energy management to promote the DR participation of households. Heating and lighting systems were chosen to be controlled by human comfort factors such as thermal comfort and visual comfort. Case studies were conducted to validate the proposed approach. The results showed that the proposed approach could effectively reduce the energy consumption during the DR period and improve the occupants’ comfort

Dynamic Thermal Modeling of Electrical Appliances for Energy Management of Low Energy Buildings

Ce travail propose un modèle thermique dynamique des appareils électriques dans les bâtiments basse consommation. L'objectif de ce travail est d'étudier l'influence des gains thermiques de ces appareils sur le bâtiment. Cette étude insiste sur la nécessité d'établir un modèle thermique dynamique des appareils électriques pour une meilleure gestion de l'énergie du bâtiment et le confort thermique de ses habitants.Comme il existe des interactions thermiques entre le bâtiment et les appareils électriques, sources de chaleur internes au bâtiment, il est nécessaire de modéliser le bâtiment. Le bâtiment basse consommation est modélisé dans un premier temps par un modèle simple reposantl'étude d'une pièce quasi-adiabatique. Ensuite, dans le but d'établir le modèle des appareils électriques, ceux-ci sont classés en quatre catégories selon leurs propriétés thermiques et électriques. A partir de cette classification et du premier principe de la thermodynamique, un modèle physique générique est établi. Le protocole expérimental et la procédure d'identification des paramètres thermiques des appareils sont ensuite présentés. Afin d'analyser la pertinence du modèle générique appliqué à des cas pratiques, plusieurs appareils électriques utilisés fréquemment dans les résidences – un écran, un ordinateur, un réfrigérateur, un radiateur électrique à convection et un micro-onde – sont choisis pour étudier et valider ce modèle ainsi que les protocoles d'expérimentation et d'identification. Enfin, le modèle proposé est intégré dans le modèle d'un bâtiment résidentiel développé et validé par le CSTB. Ce modèle couplé des appareils et du bâtiment est implémenté dans SIMBAD, un outil de simulation du bâtiment. A travers cette simulation, le comportement thermique du bâtiment et la quantité d'énergie nécessaire à son chauffage sur une période hivernale, ainsi que l'inconfort thermique dû aux appareils électriques durant l'été, sont observés.Ce travail fournit des résultats quantitatifs de l'effet thermique de différents appareils électriques caractérisés dans un bâtiment basse consommation et permet d'observer leur dynamique thermique et leurs interactions. Finalement, cette étude apporte une contribution aux études de gestion de l'énergie des bâtiments à basse consommation énergétique et du confort thermique des habitants.This work proposes a dynamic thermal model of electrical appliances within low energy buildings. It aims to evaluate the influence of thermal gains of these appliances on the buildings and persuades the necessity of dynamic thermal modeling of electrical appliances for the energy management of low energy buildings and the thermal comfort of inhabitants.Since electrical appliances are one of the free internal heat sources of a building, the building which thermally interact with the appliances has to be modeled. Accordingly, a test room which represents a small scale laboratory set-up of a low energy building is first modeled based on the first thermodynamics principle and the thermal-electrical analogy. Then, in order to establish the thermal modeling of electrical appliances, the appliances are classified into four categories from thermal and electrical points of view. After that, a generic physically driven thermal model of the appliances is derived. It is established based also on the first thermodynamics principle. Along with this modeling, the used experimental protocol and the used identification procedure are presented to estimate the thermal parameters of the appliances. In order to analyze the relevance of the proposed generic model applied to practical cases, several electrical appliances which are widely used in residential buildings, namely a monitor, a computer, a refrigerator, a portable electric convection heater, and microwave are chosen to study and validate the proposed generic model and the measurement and identification protocols. Finally, the proposed dynamic thermal model of electrical appliances is integrated into a residential building model which was developed and validated by the French Technical Research Center for Building (CSTB) on a real building. This coupled model of the appliances and the building is implemented in a building energy simulation tool SIMBAD, which is a specific toolbox of Matlab/Simulink®. Through the simulation, thermal behavior and heating energy use of the building are observed during a winter period. In addition, thermal discomfort owing to usages of electrical appliances during a summer period is also studied and quantified.This work therefore provides the quantitative results of thermal effect of differently characterized electrical appliances within a low energy building and leads to observe their thermal dynamics and interactions. Consequently, it permits the energy management of low energy buildings and the thermal comfort of inhabitants in accordance with the usages of electrical appliances

Quantitative Assessment of Energy Supply Security: Korea Case Study

Ensuring energy supply security has become one of the most important purposes for many countries. To make the strategies for ensuring the energy supply security of a country, it is essential to quantitatively assess the security. This paper aims to present a methodology to evaluate the energy supply security of a country by using different indices of energy dependence and energy diversity, which have been raised as two main paradigms of energy supply security. This study also proposes two indices reflecting the correlation between a country’s energy diversity and energy import dependence to evaluate its energy supply security based on easily accessible data. The presented methodology and indices were applied to the evaluation of the primary energy supply security of Korea from 1991 to 2018. The results show that a country highly dependent on energy imports is not evaluated as secure enough in terms of energy supply even if it obtains higher energy diversity. This finding supports the importance of the correlation of energy dependence and energy diversity of a country to ensure its energy supply security. This approach could be further adapted to other countries and help them to make their energy policy and strategies

Surface Discharge Mechanism on Epoxy Resin in Electronegative Gases and Its Application

This study presents the surface discharge characteristics of insulating gases, including sulfur hexafluoride (SF6), dry air, and N2, under a non-uniform field. Surface discharge experiments were conducted, with the gas pressure ranging from 0.1 to 0.6 MPa, on samples of epoxy dielectrics under an AC voltage. The experimental results showed that the surface insulation performance significantly improved in insulating gases possessing electronegative gases, such as SF6 and dry air. Surface flashover voltages of SF6 were saturated with an increasing pressure, compared to dry air and N2. The surface discharge mechanism is proposed to explain the improvement and saturation of dielectric characteristics of the electronegative gas in complex dielectric insulations, as well as its influence on the surface flashover voltage. As an application, an insulation design method is discussed with regards to replacing SF6 gas in high-voltage power equipment based on the knowledge of the physics behind gas discharge

Quantitative Assessment of Energy Supply Security: Korea Case Study

Ensuring energy supply security has become one of the most important purposes for many countries. To make the strategies for ensuring the energy supply security of a country, it is essential to quantitatively assess the security. This paper aims to present a methodology to evaluate the energy supply security of a country by using different indices of energy dependence and energy diversity, which have been raised as two main paradigms of energy supply security. This study also proposes two indices reflecting the correlation between a country’s energy diversity and energy import dependence to evaluate its energy supply security based on easily accessible data. The presented methodology and indices were applied to the evaluation of the primary energy supply security of Korea from 1991 to 2018. The results show that a country highly dependent on energy imports is not evaluated as secure enough in terms of energy supply even if it obtains higher energy diversity. This finding supports the importance of the correlation of energy dependence and energy diversity of a country to ensure its energy supply security. This approach could be further adapted to other countries and help them to make their energy policy and strategies

A Novel Application of Fractional Order Derivative Moth Flame Optimization Algorithm for Solving the Problem of Optimal Coordination of Directional Overcurrent Relays

The proper coordination of directional overcurrent relays (DOCRs) is crucial in electrical power systems. The coordination of DOCRs in a multi-loop power system is expressed as an optimization problem. The aim of this study focuses on improving the protection system’s performance by minimizing the total operating time of DOCRs via effective coordination with main and backup DOCRs while keeping the coordination constraints within allowable limits. The coordination problem of DOCRs is solved by developing a new application strategy called Fractional Order Derivative Moth Flame Optimizer (FODMFO). This approach involves incorporating the ideas of fractional calculus (FC) into the mathematical model of the conventional moth flame algorithm to improve the characteristics of the optimizer. The FODMFO approach is then tested on the coordination problem of DOCRs in standard power systems, specifically the IEEE 3, 8, and 15 bus systems as well as in 11 benchmark functions including uni- and multimodal functions. The results obtained from the proposed method, as well as its comparison with other recently developed algorithms, demonstrate that the combination of FOD and MFO improves the overall efficiency of the optimizer by utilizing the individual strengths of these tools and identifying the globally optimal solution and minimize the total operating time of DOCRs up to an optimal value. The reliability, strength, and dependability of FODMFO are supported by a thorough statistics study using the box-plot, histograms, empirical cumulative distribution function demonstrations, and the minimal fitness evolution seen in each distinct simulation. Based on these data, it is evident that FODMFO outperforms other modern nature-inspired and conventional algorithms

IoT-Based Smart Building Environment Service for Occupants’ Thermal Comfort

This paper presents an Internet of Things (IoT) platform for a smart building which provides human care services for occupants. The individual health profiles of the occupants are acquired by the IoT-based smart building, which uses the accumulated knowledge of the occupants to provide better services. To ensure the thermal comfort of the occupants inside the building, we propose a dynamic thermal model of occupants. This model is based on the heat balance equation of human body and thermal characteristics of the occupants. We implement this model in two smart building models with heaters controlled by a temperature and thermal comfort index using MATLAB/Simulink®. The simulation results show that the thermal comfort-based control is more effective to maintaining occupants’ thermal satisfaction and is therefore recommended for use providing human care services using IoT platforms in smart buildings

Residential building energy demand and thermal comfort: Thermal dynamics of electrical appliances and their impact

International audienc