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Improving Reliability and Economic Performance of Microgrids - A short course jointly organized by School of Electrical and Electronic Engineering, NTU and IEEE Singapore Section –

Introduction In recent years, the renewable power generation has been seen as an effective way to resolve

the global energy crisis and reduce the carbon footprint. However, the intermittent

characteristics of renewable energy sources such as wind and solar energy systems give rise

to great challenges on coordination and balancing issues between supply and demand.

Microgrids as a platform to incorporate renewable and alternative energy resources and

advanced energy storage systems can provide intelligence for monitoring and control of

distribution systems to enhance their availability, reliability and efficiency.

With the continuous and advanced development of the microgrid technologies, the basic

theory and energy cooperation management technologies of the microgrids have been

developed and improved. The researchers in both the academic and industrial sectors have

been working hard on promoting the practical applications and commercialization of the

microgrids. They still face many challenges such as improving the reliability, economic

performance, and power quality issues.

Since 2014, our research team has been working on the Economic Development Board (EDB)

funded project entitled “Improving Reliability and Economic Performance of Microgrids”. In this

project, a novel microgrid configuration including the adaptive demand response management

(DRM), advanced solid state transformer (SST) based hybrid energy storage system (HESS)

and unified power quality conditioner (UPQC) is proposed as shown in Figure 1.

Loads

Demand Response

Management

Electricity

pricing

Maximum Demand Control

with Contracted Capacity

Optimization

Local Control Agents

Local Protection Elements

Communication and control network

Electrical Network

Forecasting of

solar and wind

Market OperationsEnergy Management

System

Wind Solar PV

Energy

Management

System for

Economic Dispatch

Hybrid Energy

Storage System

Charge and

Discharge

commands to

HESS

Wind and solar

irradiance data

Grid

Micro

Turbine

HESS Fuel Cell

Power Quality

Improvement with

UPQC

Vdc

UPQC

SST

DC

DC

DC

AC

HFT

Battery

Generation

Scheduling

Power

Quality and

Reliability

Electricity

Bill

Reduction Figure 1. Configuration of the proposed microgrid including the UPQC, HESS and adaptive DRM

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By using the adaptive demand response management (DRM), SST based HESS and UPQC,

the microgrid is expected to mitigate the intermittent nature of renewable energy sources;

improve the power quality of the supply; lower the schedule cost; as well as balance the supply

and demand. This course will reveal the latest research achievements of this EDB funded

project. The following aspects of the project will be taught in the course:

(1) The functionalities of adaptive DRM operating in microgrids is shown in Figure 2.

Compared to DRM applied in upstream grids, DRM applied in microgrids in an interconnected

mode will further improve the market efficiency. With the support of DRM applied in microgrids,

even the small customers are able to respond to real-time market prices. The impact of DRM

can thus be extended to a larger variety of customers. With a higher participation rate of the

customers in DRM, peak demand could be further lowered by incentivized consumers who

respond to a higher real-time price via automated intelligent energy management devices.

Therefore, the total generation cost can be reduced and generation efficiency will be improved.

From an economic benefit viewpoint, an effective DRM system is able to optimize the total

profits of microgrids by taking into account the unique features of the distributed generation

resources in microgrids.

Figure 2. Functionalities of DRM operating in microgrids

(2) The configuration of HESS connected to a microgrid using SST is shown in Figure 3. The

HESS consists of batteries, supercapacitors and power converter systems via SSTs. By

combining the advantages of high energy density capability of batteries, and high power

density capability of supercapacitors, HESS possesses a superb capability for managing

highly fluctuating power demands. Further, HESS is used to improve the reliability, power

quality, dynamic performance, and overall microgrid schedule/operating cost. Through optimal

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power scheduling solutions of HESS, the HESS will be more cost-effective than the single-

type storage system. Since the SST is adopted in the HESS as the grid-connected interface,

the proposed technique enjoys a much reduced weight and size as compared to those

conventional power conversion approaches utilizing the power electronics converters and

regular power transformers. Besides the basic functions of charging/discharging the

batteries/supercapacitors, the SST based HESS possesses the advantages of

voltage/frequency adaption and reactive power compensation.

AL BL CL MicrogridSST

DC

DC

DC

AC

HFT

AL BL CLSST

DC

DC

DC

AC

HFT

Battery

Supercapacitor

Figure 3. SST based HESS

(3) UPQC is connected between the main grid and microgrid as shown in Figure 4. The power

transfer between main grid and the microgrid is bidirectional depending upon the power

generation in the microgrid. UPQC is able to mitigate both voltage and current power quality

problems. It protects the sensitive microgrid loads and power electronic based renewable

power generation systems from the power quality problems in the grid such as voltage

harmonics, unbalanced voltages, voltage sags and voltage swells. In addition, this UPQC

makes the main grid free from the current power quality problems created by the nonlinear

loads in the microgrid by means of supplying the reactive power and suppressing the

harmonics. Hence, this UPQC improves the reliability of the microgrid.

Figure 4. UPQC interconnected between main grid and microgrid

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(4) Short course participants will be introduced to two main development and testing concepts

i.e. rapid control prototyping (RCP) and hardware in the loop (HIL). They will learn how to

adopt the appropriate concepts depending on the user requirement. An illustration of the

development and testing concepts is shown in Figure 5.

Fgiure 5. Development and testing via rapid control prototyping and hardware-in-the-loop

Hardware and Software Demonstration

Demonstration of the abovementioned technologies based on the self-developed DRM

software and the self-built experimental prototypes of the SST based HESS, UPQC and PHIL

in the laboratory.

DRM: Maximum Demand Control (MDC) as a part of DRM reduces the electricity bill of a

microgrid or building consumer/owner; increases load factor; and smoothens the system load

profile. MDC includes three applications namely Short-Term Maximum Demand Control

(STMDC), Real-Time Maximum Demand Control (RTMDC) and Contracted Capacity

Optimization (CCO). In the hardware cum software demonstration, the following features of

MDC will be presented:

(a) Demonstration of CCO software and its modules;

(b) Demonstration of STMDC software and its modules;

(c) Demonstration of MDC software and its module;

(d) Explanation of the real-time test system and load profile;

(e) Explanation of the controllable loads which are used in the test;

(f) Running the system to demonstrate the effect of system parameters and variables; and

(g) Demonstration of its outputs: graphs and numerical results.

SST and HESS: We will perform the following hardware demonstrations:

(a) Introduction of SST and HESS configuration and principle of operation;

(b) Demonstration of charging/discharging of the battery/supercapacitor via SST and HESS;

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(c) Demonstration of parallel operation of SSTs including online switching between single

SST and two SSTs to validate the extensibility, redundancy and re-configurability benefits;

(d) Demonstration of energy management of the battery/supercapacitor;

(e) Demonstration of state of charge (SoC) regulation of the battery, i.e. operating within the

limits of SoC, through a coordinated control with the supercapacitor;

(f) Demonstration of DC bus voltage regulation of HESS;

(g) Demonstration of power sharing between the battery and supercapacitor;

(h) Demonstration of control of power sharing between the grid and HESS w.r.t. load demand.

UPQC: Demonstration of the UPQC is done for verifying its voltage and current mitigation

capabilities. Voltage compensation capability is demonstrated by regulating the microgrid

voltage even with the sag and swell conditions in the main grid. The voltage sag and swell

conditions in the main grid are created by connecting auto transformer to the grid. The current

power quality mitigation capability is demonstrated by maintaining the balanced and sinusoidal

currents from the grid even with the nonlinear load currents in the microgrid. The nonlinear

loads are emulated in the microgrid using the Chroma programmable load.

PHIL: Power hardware in the loop (PHIL) concept will be introduced which is a natural

extension of HIL. Participants will have an opportunity to view a real time demonstration of

PHIL experiments on the microgrid testbed at the Clean Energy Research Lab (S2-B7c-05) in

EEE, NTU. The PHIL experiment is performed using the state-of-art real time digital simulator

from OPAL-RT and a four quadrant power amplifier from Triphase. An overview of the PHIL

architecture is shown in Figure 6.

Figure 6. Proposed testing and architecture of power hardware in the loop (PHIL) concepts

We will perform the following hardware demonstrations

(i) Introduction of PHIL between the real-time simulator, OPAL-RT, and HESS;

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(ii) Demonstration of controlling the charging/discharging phenomenon of the battery to

regulate the grid voltage and frequency by configuring PHIL using OPAL-RT and HESS.

Course Objectives

In this course, four presentations related to the adaptive DRM, the UPQC with DG sources

and the advanced SST based HESS will be conducted. The basic concept, development and

principle of these technologies will be introduced in detail. In the demonstration section, the

function and effectiveness of the adaptive DRM will be validated using the completed DRM

software based on the microgrid in our lab. The hardware configuration, design and

implementation of the self-developed experimental laboratory prototypes of the SST based

HESS and UPQC will be introduced. The various operating modes and pre-set functions of

them will be demonstrated to validate the feasibility and practicability of these proposed

technologies.

It is expected that through this course, the participants are able to understand the principle of

operation, current R&D trend and the challenges of the technologies towards the improvement

of the economic performance and reliability and power quality of the microgrid. This course is

also a good opportunity to showcase and share with the participants our latest research

achievements in terms of improvement in the reliability and economic performance and power

quality of the microgrid. Furthermore, we would share with the participants the design rules

and implementation methodology of the proposed DRM, SST based HESS and UPQC to

promote the commercialization of these technologies.

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Course Outline

The details of the finalized course schedule will be available from the Short Course sub-menu at http://eeeweba.ntu.edu.sg/power_projects/EIRP04/ a couple weeks before the scheduled course date.

Time Activities

8:30-9:00 Registration

9:00-10:00 Lectures delivered by Prof Hoay Beng Gooi

Topic: Overview of Microgrid Management and Latest Development Trend

1. Overview of Microgrid Management System 2. Demand Response Management 3. Some Aspects of Latest Development Trend

10:00-10:30 Tea break

10:30-11:30 Lectures delivered by Prof Fengjiang Wu and Dr Sathish Kumar Kollimalla

Topic: Hybrid Energy Storage System (HESS) and Solid State Transformer

(SST) Advancement in Energy Management System for Smart Grid

1. Overview of HESS and SST 2. Configuration and control algorithms of HESS 3. Concept, configuration and potential application of SST 4. Control algorithm, design and implementation of SST for HESS

11:30-12:30 Lectures delivered by Prof Yi Tang

Topic: Unified Power Quality Conditioner (UPQC)

1. Introduction to power quality.

2. Solutions for power quality problems.

3. Working and control principles of UPQC.

12:30-13:30 Lunch

13:30-14:30 Lectures delivered by Dr Foo Eddy

Topic: Power Hardware-in-the-Loop (PHIL)

1. Overview of Real Time Digital Simulator 2. Rapid Control Prototyping, Hardware in the loop and PHIL concepts 3. PHIL applications 4. Example on NTU microgrid PHIL scenario

14:30-16:00 Hardware and Software Demonstration: DRM, SST based HESS, UPQC

and PHIL in the Clean Energy Research Laboratory (S2-B7c-05).

16:00-16:30 Tea Break

16:30-18:00 Hardware and Software Demonstration: DRM, SST based HESS, UPQC

and PHIL in the Clean Energy Research Laboratory (S2-B7c-05).

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Instructors

H. B. GOOI received his Ph.D. degree from Ohio State University in 1983.

From 1983 to 1985 he was an Assistant Professor in the EE Department

at Lafayette College. From 1985 to 1991 he was a Senior Engineer with

Empros (now Siemens), USA where he was responsible for the design

and testing of energy management system (EMS) projects. In 1991, he

joined School of EEE, NTU as a Senior Lecturer and has been an

Associate Professor since 1999. He is a registered professional engineer

in USA and Singapore. He taught EMS courses for dispatchers at Power

System Control Centre in Singapore, Indonesia and Malaysia. He was Deputy Head of Power

Engineering Division during 2008-2014. He serves as an Editor of IEEE Transactions on

Power Systems. He attracted more than S$10m research grants and serves as PI of EIRP04

and EIRP12 Project. His current research interests include microgrid energy management

systems, energy storage, renewable energy sources, electricity market and spinning reserve.

Fengjiang Wu received the B.S., M.S. and Ph.D. degrees in electrical

engineering from Harbin Institute of Technology (HIT), Harbin, China, in

2002, 2004 and 2007, respectively. Since 2007, he has been with the

Department of Electrical Engineering, HIT, where he is currently an

Associate Professor. Since 2016, he has been with the School of

Electrical and Electronic Engineering, Nanyang Technological University,

Singapore, as a Senior Research Fellow. His research interests include

the area of renewable energy generation, energy storage system,

microgrid, multilevel inverter technology and electric machines drive. He has published more

than 40 international journal and conference papers. He has filed more than 20 patents and

some of them are pending.

Sathish Kumar Kollimalla received the Bachelor’s degree from the

Viswanadha Institute of Technology and Management College of

Engineering, Visakhapatnam, India, in 2003, and the Master degree in

engineering from Andhra University, Visakhapatnam, in 2006. He

received the Ph.D. degree from Indian Institute of Technology Madras,

Chennai, India in 2015. He has worked as senior research fellow in

Central Power Research Institute, Bangalore, India during 2008 to 2010.

Currently he is holding a position of Post-Doctoral Research Fellow in

Nanyang Technological University, Singapore. His research interests include power

electronics applications in power systems, microgrid, renewable energy systems, hybrid

energy storage system and power quality.

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Yi Tang received the B.Eng. degree in electrical engineering from

Wuhan University, Wuhan, China, in 2007 and the M.Sc. and Ph.D.

degrees from the School of Electrical and Electronic Engineering,

Nanyang Technological University, Singapore, in 2008 and 2011,

respectively. From 2011 to 2013, he was a Senior Application Engineer

with Infineon Technologies Asia Pacific, Singapore. From 2013 to 2015,

he was a Postdoctoral Research Fellow with Aalborg University, Aalborg,

Denmark. Since March 2015, he has been with Nanyang Technological University, Singapore

as an Assistant Professor. He is the Cluster Director of the advanced power electronics

research program at the Energy Research Institute. Dr. Tang serves as an Associate Editor

for the IEEE Journal of Emerging and Selected Topics in Power Electronics. He received the

Infineon Top Inventor Award in 2012.

Y. S. Foo. Eddy received his B.Eng. degree in Electrical and Electronic

Engineering from Nanyang Technological University, Singapore, in 2009.

Subsequently, he received his Ph.D. degree in Electrical and Electronic

Engineering from Nanyang Technological University, Singapore, in 2016.

Between 2014 and 2016, he worked as a research engineer under the

Cambridge Centre for Advanced Research in Education in Singapore

(CARES) project which is part of the CREATE program. Between 2012

and 2014, he served as a Teaching Assistant for NTU EEE and REP. He was awarded the

NTU EEE outstanding teaching award in 2013. At present, he is a lecturer in the School of

Electrical and Electronic Engineering at Nanyang Technological University, Singapore. His

research interests are multi-agent systems, microgrid energy management systems, electricity

markets, power hardware in the loop and renewable energy resources.

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Demonstrators

N. K. Swami Naidu received the B. Tech. degree in electrical and

electronics engineering from Jawaharlal Nehru Technological University

(JNTU), Hyderabad, India, in 2007; the M.Tech. degree in power

electronics and drives from the National Institute of Technology,

Kurukshetra, India, in 2009; and the Ph.D. degree from the Electrical

Engineering Department, Indian Institute of Technology Delhi, New Delhi,

India, in 2015. He is currently working as a Research Fellow with

Nanyang Technological University, Singapore. His research interests include power

electronics, wind energy conversion systems, power quality, and microgrid-based power

systems.

Ali Khorasani Ferdavani received the B.Sc. and M.Sc. degrees from

Ferdowsi University of Mashhad, Iran, in 1995 and 1998, respectively,

and Ph.D. degree from the Universiti Teknologi Malaysia (UTM),

Malaysia, in Electrical Engineering in 2013. He is currently a Research

Fellow at Nanyang Technological University since Jan 2015. His previous

job was at UTM under the Post-Doctoral Fellowship Scheme for a

research project from Mar 2013 to Dec 2014. He was also a project

manager in some consultant electrical distribution system projects such as preparation of

comprehensive plans since 2001. Furthermore, he was a lecturer at Isfahan University of

Technology from 2005 to 2008. His research interests include power system analysis and

optimization, micro grid, smart grids, Internet of Things, reliability, and power quality.

For the brief CV of Dr. Fengjiang Wu, Dr. Sathish Kumar Kollimalla and Dr Y. S. Foo. Eddy, please refer

to the Instructor page.

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Who Should Attend?

This course is useful to engineers and managers working in clean energy, renewable energy,

converter design and operation of smart grids, microgrids and intelligent energy systems. It is

beneficial to anyone who wishes to know more about their development in Singapore. The

course will be structured towards experience sharing and knowledge transfer.

Course Information

Date: July 27, 2017 (Thursday)

Time: 8:30 to 18:00

Lecture Venue: Executive Seminar Room (S2.2-B2-53), Block S2.2, Level B2, Room 53,

School of Electrical & Electronic Engineering (EEE), NTU

Demo Venue: Laboratory for Clean Energy Research (S2-B7c-05), School of EEE, NTU

CPD Programme: This course is qualified for 7 PDUs by Professional Engineers Board

(PEB), Singapore. URL: http://www.peb.gov.sg/pe_general_co.aspx

Fee (net amount): S$600 or on site S$700 (subject to space availability)

S$550 for early bird registration by July 10, 2017 or $500 for group

registration (3 or more from the same organization registered at the same time by July 10, 2017)

Fees include refreshments, lunch and course notes. Payment is to be made payable to IEEE

Singapore Section via a Singapore cheque or bank draft in Singapore dollars. Overseas participants

are asked to contact Mrs Jasmine Leong for details of TT transfer at:

IEEE Singapore Section Secretariat

Blk 121 Paya Lebar Way

#03-2801

Singapore 381121

Tel: (65) 6743 2523

Email: sec.singapore@ieee.org

Accommodation is available at Nanyang Executive Center on a first-come, first-served basis.

Details are available at http://www.ntu.edu.sg/nec/Pages/default.aspx

The proposed course contents may be modified where practical and the course is subjected

to a minimum participation before commencement.

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Please complete the form, scan and email to the IEEE Singapore Section Secretariat before

sending the original together with the cheque/bank draft to Mrs Jasmine Leong at:

IEEE Singapore Section Secretariat

Blk 121 Paya Lebar Way

#03-2801

Singapore 381121

Tel: (65) 6743 2523 Email: sec.singapore@ieee.org

Payment by cheque/bank draft is to be made payable to IEEE Singapore Section in Singapore

dollars.