International Journal of Smart Grid and Clean Energy

Design and development of first MW-level microgrid in

Thailand

Xianwen Zhu a, c

, Suttichai Premrudeepreechacharn a

, Tirapong Kasirawat b

,

Chakphed Madtharad b

a Faculty of Engineering, Chiang Mai University, Chiang Mai, 50200, Thailand b Provincial Electricity Authority (PEA), Chiang Mai, 50200, Thailand

c NR Electric Co.,Ltd, Nanjing, 211102, China

Abstract

This paper presents the design and development of a MW-level Microgrid project at Mae Sariang District Mae Hon

Son province in northern of Thailand. The Microgrid project coverage area get power supply by a 110 km 22kV

distribution line which also pass the forest area. Thus the power supply is not stable, and the power quality is not

good, the weak power system has limited the local society development. To improve the power system in the

mentioned area, the Microgrid project has decided to build which include four local resources: 1.2MW hydro-power

plant, 4MWp solar PV, 5MW diesel generator and 3MW/1.5MWh battery energy storage system (BESS).Moreover,

Power flow study, short circuit study, dynamic study and protection system design based on various combinations of

RE systems are calculated using DIgSILENT PowerFactory software in achieving the most optimal design. The

obtained solution shows that a hybrid combination of solar/ hydro/battery/diesel is cost effective, sustainable, social-

economically and environmentally [1]. Additionally, the result shows that the Microgrid system could significantly

increase the power system stability and reliability in the Microgrid coverage area. Moreover, after lost power supply

from the main grid, by automatically black start function, the Microgrid system can supply power locally to the

customer and can reduce the outage time from at least 20 minutes to within 1 minute.

Keywords: Microgrid, BESS

1. Introduction

Mae Sariang District is about 110 km away from HOT substation.A long(110 km) 22 kV distribution

line which also pass through the forest area is the only link between the main grid and Mae Sariang

District, to reduce the power loss of the long distribution line , a 4MWp solar farm and 1.2MW hydro-

power plant are built to supply power locally, but there are still remain following main issues: The

energy loss from long distribution line is about 19% or about 6.7 million kWh per year; the number of

outage is more than 20 times per year caused by damaged equipment, maintenance, or weather related;

during peak load, diesel generator has to run to support the voltage in the area; solar farm cannot connect

to the grid in some cases caused by voltage sag, over voltage, or unbalance voltage; the operation in this

area still depends on the local operator due to the reliability of controlled equipment in SCADA system

which are sometime low battery or loss of communication. Therefore, when the outage occurs, it will take

about 20 minutes to connect and disconnect equipment before diesel generator is able to supply to the

load.Hence, the Provincial Electricity Authority (PEA) decided to build a smart microgrid by integrating

PV generation, BESS, hydro-power plant and diesel generator to enhance the local power supply, the

stability and resiliency of the power system.

Fig. 1 illustrates the power system single line diagram. It has 11 circuit breaks at substation for all

* Manuscript received August 13, 2020; revised July 7, 2020.

Corresponding author’s Tel.: +8613776540931; E-mail address: Zhuxw0801@gmail.com

doi: 10.12720/sgce.10.2.133-141

feeders which is included incoming feeder from HOA08 and HOA09(22kV source) and 1BVB(future

115kV source) . The feeder from solar farm connect to the same bus with battery in order to use battery in

many operations such as PV smoothing, peak shaving, energy management, etc. 15 load break switches

installed in this project to provide the function of load shedding, load recovery and Fault Location,

Isolation, and Service Restoration(FLISR).

Fig. 1. Power system single line diagram

Fig. 2 has been shown the typical load profile of the microgrid coverage area, the most load is come

from the residential electricity consumption, thus the peak load is happen at 6:30AM when people wake

up and start to cooking and 6:30PM when people start to use lighting and air-conditioner. And during

those peak time, PV already cannot generate power at that time , power supply is not enough, the system

voltage will drop , without microgrid system, PEA has to start Diesel generator to maintain system

voltage despite the cost of diesel oil is quite high, after microgrid system set up, it will use BESS to

discharge during the peak time. The microgrid system also can be used for voltage and frequency

dynamic regulation function when system has some disturbance .In case that there is some internal fault

happen, the Fault Location, Isolation, and Service Restoration(FLISR) function will operate to

locate ,isolate and restore the fault area automatically to reduce the outage duration. In addition, in case

the distribution line is interrupted, the coverage area will be supplied by energy sources from battery,

diesel generator, Solar farm, or hydro power plant to form as islanding area in order to increase the

reliability of the system.

Fig. 2. Typical load profile of Microgrid coverage area

134 International Journal of Smart Grid and Clean Energy, vol. 10, no. 2, April 2021

Zhu Xianwen et al.: Design and development of first MW-level microgrid in Thailand

2. System Components

Microgrid control & protection system adopts the layered and distributed design, which is divided into

local control level, coordinative control level and optimal control level. [2-4]

The topology as shown in Fig. 3:

Fig. 3. Layered Microgrid control and protection system

2.1. Local control level

The Local control level includes DGs, PCS, local controller and protection IEDs. Our automated local

control system with independent communication can provide fast response speed between equipment

during minor disturbances or short-circuit faults, and stabilize power-supply by the self-regulation of

converter or the fast action of protection equipment.

2.2. Coordinative control level

The coordinative control level includes the Microgrid controller, which acquires the information of

DGs, energy storage, diesel generators and important load via the control communication network. When

Microgrid operates in the islanded mode and large disturbance occurs (such as non-scheduled grid outage,

large-capacity DG trip, etc.), the Microgrid controller coordinates the operating modes of energy storage

and diesel generator as well as the output power of DGs to maintain the voltage and frequency within the

allowable ranges and guarantee the stable and safe operation of Microgrid system.

2.3. Optimal control level

The optimal control level includes the Microgrid EMS and depends on the data supplied by SCADA

system, dispatching & schedule system, load forecast system, etc. It realizes the functions of data analysis,

energy prediction, load management, optimal operation, economic dispatching for the specified

applications to maximize the comprehensive utilization rate of the DGs within Microgrid.

3. System Modeling

According to the problems, DIgSILENT PowerFactory software is used to show ability of the MGDP

in any case or scenario studies defined by PEA, the power system study result has also been used for

function design and relay setting calculation.

135

3.1. System modelling

The system modelling as shown in Fig. 4:

Hydro

Diesel

PV System

Battery

DC Batt 0 .000 .000 .00

LV(6)0 .411 .0317.29

22.361 .02

-13.81

22.161 .01

-13.24

22.411 .02

-13.73

22.661 .03

-12.99

LV(4)0 .390 .9819.91

LV(3)0 .390 .9819.91

LV(2)0 .390 .9819.91

LV(1)0 .390 .9819.91

TDiesel0 .000 .000 .00

M SR _ D _ 1 ( 4 )

0 .000 .000 .00

M SR _ D _ 1 ( 2 )

0 .000 .000 .00

M SR _ D _ 1 ( 1 )

0 .000 .000 .00

22.741 .03-3 .90

22.941 .04

-12.26

22.661 .03

-12.99

Terminal LF5(1)22.401.02-13.60

T F1

Terminal LF4(1)22.461.02-13.66

MAA115 .001 .000 .00

HOA0 .000 .000 .00

22.441 .02

-13.6922.451 .02

-13.67

22.421 .02

-13.72

21.010 .96

-12.25

21.650 .98-3 .90

23.061 .05-5 .96

22.761 .03-2 .46

Hydro_13 .301 .000 .00

M SR _ D _ 1

0 .000 .000 .00

MAA Bus 1

22.501.02

-13.60

21.120 .96-5 .95

21.400 .97-2 .45

MAA Bus 222.501 .02

-13.60

23.101 .050 .00

23.101 .050 .00

22.531 .02

-13.25 22.741 .03-3 .90

PowerFactory 15.1.2

Project:

Graphic: Grid

Date: 10/7/2018

Annex:

Load Flow Balanced

Nodes

Line-Line Voltage, Magnitude [kV]

Voltage, Magnitude [p.u.]

Voltage, Angle [deg]

Branches

Active Power [MW]

Reactive Power [Mvar]

Current, Magnitude [kA]

~

BESS PQ Droop Mode

P 1...Q 0...I 1...

V

DC - Batt

BESS VF Mode

LoadHOA08(3)

P 0 .9 ..Q 0.0 ..I 0 .02..

LoadHOA09(3)

P 1 .2 ..Q 0.6 ..I 0 .03..

Lin

eS

WC

ap_

a

SWCap

P 0 .0 ..Q 0.0 ..I 0 .00..

1

LoadHOA09(2)

P 1 .6 ..Q 0.8 ..I 0 .04..

LoadHOA09(1)

P 1 .1 ..Q 0.5 ..I 0 .03..

LoadHOA08(2)

P 1 .3 ..Q -0.0..I 0 .03..

LoadHOA08(1)

P 1 .1 ..Q 0.0 ..I 0 .02..

Lin

eF

4_

en

d

Load LF4(4)

P 0 .3 ..Q 0.2 ..I 0 .00..

Load F5(2)

P 0 .4 ..Q 0.2 ..I 0 .01..

Lin

eF

5_

en

d

Load LF1(3)

P 0 .2 ..Q 0.1 ..I 0 .00..

Load LF1(1)

P 0 .6 ..Q 0.3 ..I 0 .01..

Lin

eF

1_

en

d

Lin

eC

ap

_a

P 0 .0 ..Q -5.0..I 0 .12..

Capacitor MAA1CVB-01

P 0 .0 ..Q -5.0..I 0 .12..

2

Line

HO

A09

_a

Line

HO

A08

_a

PV

_T

R1

P -1 .0 ..Q 0.1 ..I 0 .02..

P 1 .0 ..Q -0.0..I 1 .47..

P 1.0 ..Q -0.0..I 1.47..

2

Load F5(1)

P 0 .5 ..Q 0.3 ..I 0 .01..

Load LF1(2)

P 0 .3 ..Q 0.2 ..I 0 .00..

SW

15Li

neF

1_a

Load LF4(1)

P 0 .6 ..Q 0.3 ..I 0 .01..

SW

14

P 0 .3 ..Q 0.1 ..I 0 .00..

PV04

P 1 .0 ..Q -0.0..I 1 .47..

PV03

P 1 .0 ..Q -0.0..I 1 .47..

PV02

P 1 .0 ..Q -0.0..I 1 .47..

PV01

P 1 .0 ..Q -0.0..I 1 .47..

Lin

eH

OA

08

_0

P -2 .0 ..Q 1.0 ..I 0 .05..

Lin

eH

OA

09

_0

P 0 .3 ..Q 0.1 ..I 0 .00..

Lin

eG

en

_a

Lin

eG

en

_a

Lin

eP

V_

0 P -4 .0 ..Q 0.2 ..I 0 .10..

Lin

eB

ES

S_

0

P -1.0 MWQ -0.4 MvarI 0.028 kA

Lin

eF

5_

0P 1 .0 ..Q 1.4 ..I 0 .04..L

ine

F1

_0

P 1 .4 ..Q 0.6 ..I 0 .03..

Lin

eF

4_

0P 1 .4 ..Q 0.6 ..I 0 .03..

Line

F3_

a

Lin

eF

2_

0

P 1 .3 ..Q 0.6 ..I 0 .03..

LineF3_bP 0 .4 ..Q 0.2 ..I 0 .01..

Line(9)

Lin

eP

V_b

Tie Bus Cable

P -4 .1 ..Q -2.8..I 0 .12..

P 4 .1 ..Q 2.8 ..I 0 .12..

Lin

eG

en

Tr4

Lin

eG

en

Tr4

Lin

eG

en

Tr3

Lin

eG

en

Tr3

Lin

eG

en

Tr2

Lin

eG

en

Tr2

Lin

eG

en

Tr1

Lin

eG

en

Tr1

L Load HOA09

P 0 .3 ..Q 0.2 ..I 0 .00..

L Load HOA08

P 0 .2 ..Q 0.9 ..I 0 .02..

G~

STAMFORD 2

G~

STAMFORD 4

Die

sel_

GS

UT

(4)

P 0 .0 ..Q 0.0 ..I 0 .00..

5

Die

sel_

GS

UT

(4)

P 0 .0 ..Q 0.0 ..I 0 .00..

5

G~

STAMFORD 5

Die

sel_

GS

UT

(2)

P 0 .0 ..Q 0.0 ..I 0 .00..

5

Die

sel_

GS

UT

(2)

P 0 .0 ..Q 0.0 ..I 0 .00..

5

G~

STAMFORD 3

Grid MAA115kV

0 .00 MW0.00 Mvar

1 .00

HOA09Grid

4 .07 MW2.17 Mvar

0 .88

SW13

SW

7

SW

6

SW

11 SW

12

SW

2

SW

1

SW

4

SW

3P 0 .7 ..Q 0.3 ..I 0 .02..

2-W

ind

ing

..

P 0 .0 ..Q 0.0 ..I 0 .00..

P -0 .0 ..Q -0.0..I 0 .00..

P 0.0 ..Q 0.0 ..I 0.00..

8

Lin

e

Grid HOT115kV

Load LF3(3)

P 0 .4 ..Q 0.2 ..I 0 .01..

SW10

SW5

Load LF3(2)

P 0 .5 ..Q 0.3 ..I 0 .01..

SW9P 0 .9 ..Q 0.5 ..I 0 .02..

SW

8Li

neF

2_b

P -0 .5 ..Q -0.3..I 0 .01..

Load LF2(2)

P 0 .5 ..Q 0.3 ..I 0 .01..

Line

F2_

a

Die

sel_

GS

UT

(1)

P 0 .0 ..Q 0.0 ..I 0 .00..

5

Die

sel_

GS

UT

(1)

P 0 .0 ..Q 0.0 ..I 0 .00..

5

Die

sel_

GS

UT

P 0 .0 ..Q 0.0 ..I 0 .00..

5

Die

sel_

GS

UT

P 0 .0 ..Q 0.0 ..I 0 .00..

5

HOA08Grid

6 .27 MW0.98 Mvar

0 .99

Line

BE

SS

_a

Lin

eP

V_a

Lin

e(

5)

Lin

e(

5)

P 0 .0 ..Q -0.0..I 0 .00..

G~

MITSU 1

P 0 .0 ..Q 0.0 ..I 0 .00..

G~

STAMFORD 1

Lin

eF

1_

b

Line

F5_

a

Lin

eF

3_

0

P 1 .7 ..Q 0.8 ..I 0 .04..

Line

F4_

a

PV

_T

R4

P -1 .0 ..Q 0.1 ..I 0 .02..

P 1 .0 ..Q -0.0..I 1 .47..

P 1.0 ..Q -0.0..I 1.47..

2

PV

_T

R3

P -1 .0 ..Q 0.1 ..I 0 .02..

P 1 .0 ..Q -0.0..I 1 .47..

P 1.0 ..Q -0.0..I 1.47..

2PV

_T

R2

P -1 .0 ..Q 0.1 ..I 0 .02..

P 1 .0 ..Q -0.0..I 1 .47..

P 1.0 ..Q -0.0..I 1.47..

2

Hy

dro

_G

SU

T

P -0 .0 ..Q -0.0..I 0 .00..

P 0 .0 ..Q 0.0 ..I 0 .00..

P 0.0 ..Q 0.0 ..I 0.00..

2

HO

A0

9 A

VR

2

P 2 .8 ..Q 1.4 ..I 0 .08..

P -2 .8 ..Q -1.4..I 0 .08..

P 2.8 ..Q 1.4 ..I 0.08..

6

HO

A0

8 A

VR

2

P 4 .8 ..Q 0.4 ..I 0 .13..

P -4 .8 ..Q -0.4..I 0 .12..

P 4.8 ..Q 0.4 ..I 0.13..

8

HO

A0

8 A

VR

1

P 2 .3 ..Q 0.0 ..I 0 .06..

P -2 .3 ..Q -0.0..I 0 .05..

P 2.3 ..Q 0.0 ..I 0.06..

8

HO

A0

9 A

VR

1

P 0 .0 ..Q -0.0..I 0 .00..

P -0 .0 ..Q 0.0 ..I 0 .00..

P 0.0 ..Q -0.0..I 0.00..

5

Load F5(3)

P 0 .1 ..Q 1.0 ..I 0 .02..

Load LF1(4)

P 0 .2 ..Q 0.1 ..I 0 .00..

Load LF2(1)

P 0 .7 ..Q 0.4 ..I 0 .02..

Load LF3(1)

P 0 .7 ..Q 0.4 ..I 0 .02..

Load LF4(2)

P 0 .4 ..Q 0.2 ..I 0 .01..

F in e F1 _ c

Line

F4_

b

2-W

ind

ing

..

P 1.0 ..Q 0.4 ..I 1.53..

0

Ze

qZ

pu

-0

-1

(1

)

P 1 .2 ..Q 0.6 ..I 0 .03..

P -1 .2 ..Q -0.6..I 0 .03..

Ze

qZ

pu

-0

-1

(3

)

P 0 .0 ..Q -0.0..I 0 .00..

P -0 .0 ..Q 0.0 ..I 0 .00..

Zeq

Zp

u-

0-

1

P 3 .0 ..Q 1.6 ..I 0 .08..

Ze

qZ

pu

-0

-1

(7

)

P 2 .3 ..Q 0.0 ..I 0 .05..

P -2 .2 ..Q 0.0 ..I 0 .05..

Ze

qZ

pu

-0

-1

(6

)

Ze

qZ

pu

-0-1

(5)

DIg

SIL

EN

T

Fig. 4. The all power system modelling in DIgSILENT PowerFactory software

3.2. Cases definition

All the case definition as shown in Table 1.

Table 1.Case definition

Case

No.

Grid-connected

Islanding PV BESS Diesel Hydro 115kV HOA08 HOA09

1081 0 1 0 0 1 1 1 1

1082 0 1 0 0 1 1 0 0

1083 0 1 0 0 0 0 1 0

1091 0 0 1 0 1 1 1 1

1092 0 0 1 0 1 1 0 0

1093 0 0 1 0 0 0 1 0

1151 1 0 0 0 1 1 1 1

1152 1 0 0 0 1 1 0 0

1153 1 0 0 0 0 0 1 0

0001 0 0 0 1 1 1 1 1

0002 0 0 0 1 1 1 0 0

0003 0 0 0 1 0 0 1 0

Remark: Status 1: Connected Status 0: Disconnected

For example, Case No. 1081: The power system connect to 22kV system at HOA08 together with

BESS, PV power plant, Diesel generators, and Hydro power plant. The simulation result of case 1081 has

been shown on Fig. 5., Fig. 6. and Fig. 7..

136 International Journal of Smart Grid and Clean Energy, vol. 10, no. 2, April 2021

Zhu Xianwen et al.: Design and development of first MW-level microgrid in Thailand

(a) (b)

Fig.5. Case 1081: (a)Voltage profile and (b) Active power profile

Fig. 6. Dynamic study of case 1081without BESS

In this case without BESS, voltage and frequency deviation may not comply with PEA regulation.

Fig. 7. Dynamic study of case 1081 with BESS

In this case with BESS, the BESS discharge/charge active power (-1.96 or -2.54 MW) and reactive

power (-0.24 or 1.41 Mvar) to regulate the voltage and frequency, can comply with the PEA regulation

without any outage.

4.

System Function Design

The design follows the connection standard IEEE 1547[5]. The Microgrid system is designed to

137

operate in both grid connecting and islanding mode [6] and more detail can be explained as following:

4.1. Scenario definition

Scenario 1 Before islanding

Scenario 1A grid connecting with 115kV incoming; Scenario 1B grid connecting with both HOA08

and HOA09 with tie breaker 0BVB open; Scenario 1C grid connecting with HOA08 with tie breaker

0BVB close; Scenario 1D grid connecting with HOA09 with tie breaker 0BVB close

Scenario 2 Preventive islanding if a supply interruption is planned, or an outage is expected

Intentional switching from grid connecting to islanding

Scenario 3 Automated islanding in case of unplanned grid failure

This project not have scenario 3

Scenario 4 Black start recovery to re-supply loads after grid failure

Automatic black start

Scenario 5 Maintaining the islanding

Islanding status control

Secnario 6 Reconnection to the main grid

Automatic connect back to grid

4.2. System operation mode for only have 22kV incoming:

The system will have 4 operation mode: Grid connecting open loop operation mode 1 (Scenario 1B,

0BVB open), grid connecting close loop opearation mode 2 (Scenario 1D,0BVB close), grid connecting

close loop opearation mode 3 (Scenario 1C, 0BVB close), island operation mode 4 (Scenario 5, 0BVB

close).

4.3. System operation mode for 115kV incoming:

After Mae Sariang substation 115kV incoming finished construction, the bus tie breaker will work as

normally close, 1VB 10VB will work as both feeder and back up power source in case 115kV power

source has been lost, then PCC point will have three which are 115kV incoming, HOA08 and HOA09.

4.4. System operation mode switching for 22kV incoming only

The operation mode switching as shown in Fig. 8.

Mode 2 grid connecting close loop operation

Mode 3 grid connecting close loop operation

Mode 1 grid connecting open loop operation

Trip 1VBclose 0BVB

Trip 0BVBclose 1VB

Trip 0BVBclose 10VB

Trip 10VBClose 0BVB

Mode 4 island close loop operation

Trip 1VB Close 1VBClose 10VB Trip 10VB

Fig. 8. System operation mode switching

138 International Journal of Smart Grid and Clean Energy, vol. 10, no. 2, April 2021

Zhu Xianwen et al.: Design and development of first MW-level microgrid in Thailand

Below Incoming 1 indicate for HOA08, Incoming 2 indicate for HOA09

The operation mode switching:

Logic 1: When system work in mode 1, incoming 1 lost power, bus I lost voltage, trip 1VB, PV and

BESS will stop asthmatically, close 0BVB, bus I lost power short time, go to mode 2; Switching from

Scenario 1B to 1D

Logic 2: When system work in mode 1, Incoming 2 lost power, bus II lost voltage, trip 10VB, close

0BVB, but II lost power short time, go to mode 3; Switching from Scenario 1B to 1C

Logic 3: When system work in mode 2: Incoming 2 supply to load, after that the voltage of incoming 1

has been recovered, it will trip 0BVB, then PV BESS stop automatically, bus I close 1VB, bus I lost

power short time. Switching from 1D to 1B.

Logic 4: When system work in mode 3: incoming 1 supply to load, after that the voltage of incoming 2

has been recovered, it will trip 0VBV, the diesel engine will stop, close 10VB, but II lost power for short

time, Switching from 1C to 1B

Logic 5: In case both incoming lost power, bus I and bus II both lost voltage, it will trip 1VB and

10VB, close 0BVB, go to black start mode, Scenario 4.

4.5. Function of mode 1

The function are: 1, Peak Shaving and Valley Filling, 2, Stabilize Fluctuation,3, frequency regulation,

4, voltage regulation

4.5.1. Peak shaving and valley filling

Because of its fast response and its superior peaking performance of the large-scale battery energy

storage system, in the electricity trough as the load store electrical energy, in the peak period as the power

to release energy, thereby reducing the peak valley load difference, improve the economy and safety of

power grid operation. This function can be set as “Local” or “Remote” mode. In remote mode, according

to the power plan curve transmitted by the main station (EMS), the energy storage charge and discharge

power are controlled. In local mode, the stored charge and discharge power are controlled in accordance

with the planned curve value set by this controller. The local planning curve can be formulated according

to the peak and valley price. [7-8]

4.5.2. Stabilize fluctuation

Photovoltaic output is affected by light intensity and has fluctuation characteristics. Especially in the

grid connected state, it is always in the MPPT control mode, and the change of light intensity has a great

influence on the PV output. The fast charging and discharging characteristics of the energy storage

battery can be used to stabilize the fluctuation of PV output. The fluctuation control is divided into first

order filtering control method and average filter control method according to the algorithm.

4.5.3. Frequency regulation

The Microgrid controller will detect the frequency of power grid, it will based on the offset of the

frequency, and calculate the power output of BESS bessP according to the Droop characteristic equation

and SOC of BESS, and send the power control command to BESS.

4.5.4. Voltage regulation

Voltage regulation use the controller to detect the voltage of power grid, according to the offset of the

voltage, and calculate the reactive power output of BESS bessQ

according to the Droop characteristic

equation , and send the reactive power control command to BESS.

4.6. Black start

Microgrid controller detect the open position of 1VB and 10VB, MGCC trip SW6 and SW7, limit the

139

load within 3MW via load shedding which the trip matrix is provided in the setting, the above process

will finish in 1 minute.

And then start the BESS via VSG mode, after the system voltage has been set up, then start the diesel

generator via parallel mode, after diesel generator start finish , BESS switch to PQ mode，diesel

generator check the voltage and frequency fluctuation and switching to main source mode. Then it will

automatic connect the load which has been shedding by black start.

4.7. Load recovery

In Microgrid controller will have the setting for control prohibit, when manually open or close the LBS,

and not allow Microgrid controller to automatically open and close the LBS, need control in the

Microgrid EMS to prohibit the control for LBS. Local switch at the LBS panel should be one of the input

of prohibit the control for LBS

When FLISR function isolate the fault via trip the LBS will automatically prohibit automatic control

for Microgrid controller, when the fault recover by operator, need cancel the prohibit control command in

the HMI.

Load recovery time will be set in the Microgrid controller, after the time (since it has been shedding)

finish the load will not recover to ensure the safety consideration. The maximum setting of this time will

be consider as 10 minutes.

4.8. Intentional grid connecting to island (Scenario 2)

The control center or Microgrid EMS issues the island instruction. Then the MGCC receives the island

instruction. It will start the diesel generator via parallel mode first to be ready for island mode. it will

limited the tie line power to ensure that the tie line active power and reactive power is restricted in the

allowable range via control the diesel generator and BESS, In case BESS and diesel power output is

lower than the load, need shed some load and send trip command for the LBS and send mode switching

commands to switch the diesel generator to island mode. [9-10]

4.9. Island to grid connecting

In case the island is from the intentional island command, it will not automatically connect back the

grid even the voltage of grid side is normal. In case the island is not from the intentional island command,

after the Microgrid controller detect the voltage of power grid side has recovered, it will control the

voltage and frequency of diesel generator, the voltage and frequency of Microgrid side to synchronize

close the LBS to connect back the power grid. After connect back to grid, change the diesel generator

back to parallel mode.

5. Conclusions

The key issue for access for big scale distributed renewable energy is the voltage stability and power

quality issue due to the unstable of the power generation of distributed renewable energy such as PV or

wind farm. Microgrid is a locally controllable power system composed of distributed generation

(Wind/Solar/Diesel, etc), energy storage and load, which can be connected to bulk power system and

islanding operation and it is also an autonomous system to realize control, protection and management by

itself, further more it is an efficient way to make full use of distributed generation. This paper introduces

the background of Thailand first MW level smart Microgrid project at Mae Sariang, Chiang Mai Thailand.

A typical topology and function design for Microgrid project at rural area also has been proposed in this

paper which is possible to use in other similar Microgrid project. DIgSILENT PowerFactory is used to

simulate the power system study of the area for the purpose of function design and relay setting

calculation. Finally, the microgrid system can increase reliability and stability, reduce SAIDI and SAIFI

and reduce greenhouse gas emission. Consequently, Mae Sariang district becomes green community.

140 International Journal of Smart Grid and Clean Energy, vol. 10, no. 2, April 2021

Zhu Xianwen et al.: Design and development of first MW-level microgrid in Thailand

Conflict of Interest

The authors declare no conflict of interest.

Author Contributions

A, C conducted the research; B analyzed the data; A, C wrote the paper; all authors had approved the

final version.

Acknowledgements

First and foremost, I would like to show my deepest gratitude to my adviser, Dr. Suttichai

Premrudeepreechacharna, a respectable, responsible and resourceful scholar, who has provided me with

valuable guidance in every stage of the writing of this paper. Without his enlightening instruction,

impressive kindness and patience, could not have completed my paper. His keen and vigorous academic

observation enlightens me not only in this paper but also in my future study. Last but not least, I' d like to

thank all my friends for their encouragement and support.

References

[1] Tirapong K, Patompong B, Titti B. PEA Microgrid design for coexistence with local community and environment: Case study

at Khun Pae village Thailand. IEEE Innovative Smart Grid Technologies-Asia (ISGT-Asia), 2017; (1-5).

[2] Suttichai P . Microgrid controller: Control and operation- Thailand IEEE,Session 3.2 13 Sep 2018.

[3] Haobin Z, Guangfu X, Xianwen Z, Qunbing Y, Jun C, Xu L. Microgrid coordinated control system with VSG-CIRED

Workshop - Ljubljana, 7-8 June 2018.

[4] NR Electric Co., Ltd. PCS-9617MG Microgrid controller, 2017.

[5] IEEE Standard for Interconnecting Distributed Resources with Electric Power Systems, IEEE std 1547-2003-2014.

[6] Li FS, Li RS, Zhou FQ. Microgrid Technology and Engineering Application, Academic Press, 2016.

[7] Moghimi M, Leskarac D, Panchal C, Lu J, Stegen S. Energy management system for peak shaving in an experimental

microgrid employing MILP optimization. International Journal of Engineering and Innovative Technology (IJEIT), January

2018.

[8] Estefanía P, Jon A, José IG, Iñigo Martínez de A, Edorta I. AC and DC technology in Microgrids: A review. Renewable and

Sustainable Energy Reviews, Mar, 2015; 43: 726- 749.

[9] Loh PC, Ding L. Chai Y, and Blaabjerg F. Autonomous operation of hybrid microgrid with AC and DC subgrids. IEEE Trans.

Power Electron., May 2013; 28(5): 2214-2223.

[10] Cho C, Jeon JH, Kim JY et al. Active synchronizing control of a microgrid. IEEE Trans. Power Electronics. 2011; 26(12):

3707-3719.

Copyright © 2021 by the authors. This is an open access article distributed under the Creative Commons Attribution License (CC

BY-NC-ND 4.0), which permits use, distribution and reproduction in any medium, provided that the article is properly cited, the use

is non-commercial and no modifications or adaptations are made.

141