JCM_TH_AM017_ver01.0
Sectoral scope: 02
Joint Crediting Mechanism Approved Methodology TH_AM017“Low-carbon Operation for Power Grid Utilizing Online Voltage-var(Q) Optimal Control
with ICT”

A. Title of the methodology
Low-carbon Operation for Power Grid Utilizing Online Voltage-var(Q) Optimal Control with
ICT, Version 01.0

B. Terms and definitions
Terms
OPENVQ

Definitions
OPENVQ stands for Optimized Performance Enabling
Network for Volt-var (Q).
OPENVQ is a software typically installed in power grid
control rooms that collects data of transmission system
online, forecasts the future system condition, automaticallycalculates optimum voltage control profile, and controls
voltage and reactive power remotely after verifying thestability of the transmission system.

C. Summary of the methodology
Items
GHG

emissionmeasures

Summary
reduction This methodology applies to projects that aim at reducing
transmission loss by introducing OPENVQ and optimizing
voltage and reactive power of transmission system.

Calculation
emissionsofreference Reference emissions are GHG emissions attributed totransmission loss calculated on the basis of historical voltage
profile, historical reactive power profile, and condition oftransmission system after implementation of the project.
Transmission loss is calculated by the calculation formulabased on electric circuit theory, which is adopted by Electricity1

JCM_TH_AM017_ver01.0
Sectoral scope: 02
Generating Authority of Thailand (EGAT). Reference voltage
profile is determined by the mode value calculated from ananalysis of distribution of the historical voltage measured
during a period of at least one year prior to the period not earlier
than 6 months before starting operation of the project.
Reference reactive power is determined based on the reference
voltage profile and active power of transmission line measured
after implementation of the project.
Calculationofproject Project emissions are calculated on the basis of transmission

emissionsloss calculated from the monitored values using the formulabased on electric circuit theory, which is adopted by EGAT.

Monitoring parameters

Active power, reactive power, voltage, resistance, reactance,
susceptance of the transmission line, and the number oftransmission lines in the project area X are measured.
Reference/project transmission line loss, reference reactive
power and reference voltage are calculated and monitored in
OPENVQ system based on the measured parameters.

D. Eligibility criteria
This methodology is applicable to projects that satisfy all of the following criteria.
Criterion 1

The project installs OPENVQ to the control system of transmission network.

Criterion 2

The project transmission network is one of the five regional networks servedby EGAT, in which each network is controlled by respective regional control
center (RCC). The project transmission network has delivery points which areconnected to the regional distribution network corresponding to each of the five
regions managed by Metropolitan Electricity Authority (MEA), and four
Provincial Electricity Authorities (PEA), Northeast, South, North, and Central,
respectively. The project transmission network consists of transmission lines of
500kV, 230kV, and 115kV, and substations.

Criterion 3

The project transmission network is monitored and operated on-line, and thedata of active power, reactive power, voltage, resistance, and susceptance of thetransmission line is collected remotely.

Criterion 4

The difference between reference transmission line loss calculated based on theprocedure described in F.2 and calculated transmission line loss based on thedata measured during sampling period is less than the difference between
measured substation loss and simulated substation loss in the case of installing2

JCM_TH_AM017_ver01.0
Sectoral scope: 02
OPENVQ based on the data measured during sampling period. This isconfirmed by satisfying the following formula:
𝑃𝐿𝑅𝐸,𝑋,𝑙𝑖𝑛𝑒𝑠 − 𝑃𝐿𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑,𝑋,𝑙𝑖𝑛𝑒𝑠< 𝑃𝐿𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑,𝑋,𝑠𝑢𝑏𝑠𝑡𝑎𝑡𝑖𝑜𝑛𝑠 − 𝑃𝐿𝑂𝑃𝐸𝑁𝑉𝑄,𝑋,𝑠𝑢𝑏𝑠𝑡𝑎𝑡𝑖𝑜𝑛𝑠
𝑃𝐿𝑅𝐸,𝑋,𝑙𝑖𝑛𝑒𝑠=

Reference transmission line loss (W)𝑃𝐿𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑,𝑋,𝑙𝑖𝑛𝑒𝑠=

Measured transmission line loss in thesampling period (W)𝑃𝐿𝑚𝑒𝑎𝑠𝑢𝑟𝑒𝑑,𝑋,𝑠𝑢𝑏𝑠𝑡𝑎𝑡𝑖𝑜𝑛𝑠=

Measured substation loss in the sampling
period (W)

𝑃𝐿𝑂𝑃𝐸𝑁𝑉𝑄,𝑋,𝑠𝑢𝑏𝑠𝑡𝑎𝑡𝑖𝑜𝑛𝑠=

Simulated substation loss in the case of
installing OPENVQ (W)The detail steps to confirm validity of calculation method of reference
emissions are described in Additional Information.

E. Emission Sources and GHG types
Reference emissions
Emission sources

GHG types

Transmission loss of transmission line

CO2

Project emissions
Emission sources

GHG types

Transmission loss of transmission line

CO2

F. Establishment and calculation of reference emissions
F.1. Establishment of reference emissions
By introduction of OPENVQ, transmission loss is reduced by optimizing voltage and reactive
power of transmission system. Reference emissions attributed to reference transmission loss
are calculated on the basis of historical voltage profile, historical reactive power profile, andcondition of transmission network after implementation of the project. Transmission loss oftransmission line i (𝑃𝐿𝑙𝑖𝑛𝑒𝑖 ) which connects bus 𝑘 and bus l is calculated by the calculation3

JCM_TH_AM017_ver01.0
Sectoral scope: 02
formula of EGAT:
𝑃𝐿𝑙𝑖𝑛𝑒𝑖 = 𝑃𝑘,𝑖 + 𝑃̃𝑖≡ 𝑓(𝑃𝑘,𝑖 , 𝑄𝑘,𝑖 , 𝑉𝑘,𝑖 , 𝑉𝑙,𝑖 , 𝑅𝑖 , 𝑋𝑖 , 𝐵𝑖 ),and intermediate formula is shown as below:𝑃̃𝑖 = 𝑉̃𝑙2 𝑌𝑖 ⋅ cos 𝜃 − 𝑉𝑘,𝑖 ⋅ 𝑉̃𝑙 𝑌𝑖 ⋅ cos(𝜃 − 𝜃̃ )
𝑉̃𝑙 =
𝑌𝑖 =

2
𝑉𝑘,𝑖
⋅ 𝑌𝑖 ⋅ cos 𝜃 − 𝑃𝑘,𝑖
𝑉𝑘,𝑖 ⋅ 𝑌𝑖 ⋅ cos(𝜃 + 𝜃̃ )1
√𝑅𝑖2 + 𝑋𝑖2

𝜃 = −tan−1

𝑋𝑖
𝑅𝑖
2

2

𝑄𝑘,𝑖 +𝑉𝑘,𝑖 ⋅𝑌𝑖 ⋅sin 𝜃+𝑉𝑘,𝑖 ⋅𝐵𝑖 /2𝜃̃ = −𝜃 + tan−1 ().
𝑉 2 ⋅𝑌 ⋅cos𝜃−𝑃
𝑘,𝑖

𝑖

𝑘,𝑖

Where
𝑃𝐿𝑙𝑖𝑛𝑒𝑖=Transmission loss of transmission line i (W)

Pk,i

=

Active power at the bus k of transmission line i (W)

Qk,i

=

Reactive power at the bus k of transmission line i (var)

Vk,i

=

Voltage measured at the bus k of transmission line i (V)

Vl,i

=

Voltage measured at the bus l of transmission line i (V)Yi=

Admittance of transmission line i (S)Ri=Resistance of transmission line i (Ω)

Xi=

Reactance of transmission line i (Ω)

Bi=

Susceptance of transmission line i (S)Each parameter of transmission line i which connects bus k and bus l shows a value describedin the figure below:

4

JCM_TH_AM017_ver01.0
Sectoral scope: 02

A reference voltage profile is determined by identifying the mode value of the historical voltageof each transmission line. The mode value is calculated through analysis of histogram
representing a distribution of the ratio of historical voltage to the base voltage. The historicalvoltage is measured for at least one year before implementation of the project. Reference
voltage is determined by multiplying the mode value of the ratio by the base voltage of eachtransmission line per transmission capacity.
Reactive power is derived by equation based on a voltage profile, active power and conditionof transmission system, as determined by resistance, reactance and susceptance. Therefore,
reference reactive power is determined based on the reference voltage profile, active power oftransmission line measured after implementation of the project, and condition of transmission
system after implementation of the project.
Ensuring net emission reduction
Through the introduction of OPENVQ, loss at the transmission lines and substations in the
project network is expected to be reduced. The methodology ensures net emission reduction by
not taking into account reduction of electricity consumption attributed to reduction of loss atthe substations in the project network which occurs as a result of introduction of OPENVQ.
F.2. Calculation of reference emissions(1)

𝑅𝐸𝑝 = 𝑃𝐿𝑅𝐸,𝑋,𝑙𝑖𝑛𝑒𝑠,𝑝 × 𝐸𝐹𝐺𝑟𝑖𝑑
Where
𝑅𝐸𝑝
𝑃𝐿𝑅𝐸,𝑋,𝑙𝑖𝑛𝑒𝑠,𝑝𝐸𝐹𝐺𝑟𝑖𝑑＝ Reference emission during the period p (tCO2/p)＝ Reference transmission line loss at transmission lines in the project
area X during the period p (MWh/p)＝ CO2 emission factor for grid (tCO2/MWh)𝑁(2)

𝑃𝐿𝑅𝐸,𝑋,𝑙𝑖𝑛𝑒𝑠,𝑝 = ∑ 𝑃𝐿𝑅𝐸,𝑙𝑖𝑛𝑒𝑖,𝑝
𝑖=1

Where
𝑃𝐿𝑅𝐸,𝑙𝑖𝑛𝑒𝑖,𝑝N＝ Reference transmission line loss at transmission line i during theperiod p (MWh/p)＝ Number of transmission lines in the project area X (-)
𝑝

𝑃𝐿𝑅𝐸,𝑙𝑖𝑛𝑒𝑖,𝑝 = ∑ 𝑃𝐿𝑅𝐸,𝑙𝑖𝑛𝑒𝑖,𝑡 ×𝑡=0

𝑇× 10−660

5(3)

JCM_TH_AM017_ver01.0
Sectoral scope: 02
Where
𝑃𝐿𝑅𝐸,𝑙𝑖𝑛𝑒𝑖,𝑡＝ Reference transmission line loss at transmission line i at the time t(W)
T= Measurement interval (min)𝑃𝐿𝑅𝐸,𝑙𝑖𝑛𝑒𝑖,𝑡 is calculated based on the calculation formula of EGAT, which is described in
Section F.1.
𝑃𝐿𝑅𝐸,𝑙𝑖𝑛𝑒𝑖,𝑡 ＝𝑓(𝑃𝑘,𝑖,𝑡 , 𝑄𝑅𝐸,𝑘,𝑖,𝑡 , 𝑉𝑅𝐸,𝑘,𝑖 , 𝑉𝑅𝐸,𝑙,𝑖,𝑡 , 𝑅𝑖 , 𝑋𝑖 , 𝐵𝑖 )

(4)

Where
Pk,i,t=Active power at the bus k of transmission line i at the time t (W)QRE,k,i,t=Reference reactive power at the bus k of transmission line i at the timet (var)

𝑉𝑅𝐸,𝑘,𝑖=Reference voltage at the bus k of transmission line i (V)𝑉𝑅𝐸,𝑙,𝑖,𝑡=Reference voltage at the bus l of transmission line i at the time t (V)Ri=

Resistance of transmission line i (Ω)

Xi=

Reactance of transmission line i (Ω)

Bi=

Susceptance of transmission line i (S)Since active power will not be affected by the introduction of OPENVQ, active power
measured during the project period Pk,i,t is used to represent reference active power.
Ri, Xi, Bi, are parameters related to the specification of the transmission lines. The values arecalculated based on the configuration characteristics of transmission line i at the time ofvalidation. Reference voltage VRE,k,i, VRE,l,i,t, and reference reactive power QRE,k,i,t are derived
by the following steps:
Step 1: Obtain voltage data Vk,i (V) measured at bus k for each transmission line i whichconnects bus k and bus l in the project area for a certain day of each month for one year set
at regular interval (total at least 12 days) prior to the period not earlier than 6 months before
starting operation of OPENVQ.
Step 2: Calculate the ratio of Vk,i to the base voltage Vbase,i (V) of transmission line i. Thebase voltage Vbase,i is the rated voltage of buses which are connected by transmission line i.
𝑅𝑎𝑡𝑖𝑜𝑘 =𝑉𝑘,𝑖𝑉𝑏𝑎𝑠𝑒,𝑖(5)

Step 3: Plot all obtained values of Ratiok, (-) for all transmission lines in the project areawith an interval of 0.01 which can be demonstrated in the form of a histogram.

6

JCM_TH_AM017_ver01.0
Sectoral scope: 02
Step 4: Select the most frequently observed value of Ratiomode (-).
Step 5: Calculate reference voltage VRE,k,i by multiplying Ratiomode by the base voltage Vbase,iof transmission line i.
(6)

𝑉𝑅𝐸,𝑘,𝑖 = 𝑅𝑎𝑡𝑖𝑜𝑚𝑜𝑑𝑒 ∙ 𝑉𝑏𝑎𝑠𝑒,𝑖Step 6: Reference voltage at bus l is calculated as a function of VRE,k,i.

(7)

𝑉𝑅𝐸,𝑙,𝑖,𝑡 = 𝑉𝑅𝐸,𝑘,𝑖 − 𝑋𝑖 ∙ 𝑄𝑘,𝑖,𝑡
Where
Qk,i,t=Reactive power at the bus k of transmission line i at the time t (var)

Step 7:
Reference reactive power (QRE,k,i,t) is derived by the following equations:2
𝑄𝑅𝐸,𝑘,𝑖,𝑡 = 𝑌𝑖 ∙ 𝑉𝑅𝐸,𝑘,𝑖∙ 𝑠𝑖𝑛 𝜙 − 𝑌𝑖 ∙ 𝑉𝑅𝐸,𝑘,𝑖 ∙ 𝑉𝑅𝐸,𝑙,𝑖,𝑡 ∙ 𝑠𝑖𝑛(𝛿 + 𝜙) −

𝛿 = 𝑠𝑖𝑛−1

𝐵𝑖 2∙𝑉
2 𝑅𝐸,𝑘,𝑖(8)

𝑋𝑖 ∙ 𝑃𝑘,𝑖,𝑡
𝑉𝑅𝐸,𝑘,𝑖 ∙ 𝑉𝑙,𝑖,𝑡

(9)

𝑋𝑖
𝑅𝑖

(10)

𝜙 = tan−1
1

𝑌𝑖 =√𝑅𝑖2 + 𝑋𝑖2

(11)

Where
QRE,k,i,t=Reference reactive power at the bus k of transmission line i at the timet (var)Yi=

Admittance of transmission line i (S)𝑉𝑅𝐸𝑘,𝑖=

Reference voltage at the bus k of transmission line i (V)𝑉𝑅𝐸,𝑙,𝑖,𝑡=Reference voltage at the bus l of transmission line i at the time t (V)𝜙=Impedance angle (rad)𝛿=Phase angle (rad)Vl,i,t=Voltage measured at the bus l of transmission line i at the time t (V)Pk,i,t=Active power at the bus k of transmission line i at the time t (W)

Ri=

Resistance of transmission line i (Ω)

Xi=

Reactance of transmission line i (Ω)

Bi=

Susceptance of transmission line i (S)7

JCM_TH_AM017_ver01.0
Sectoral scope: 02

G. Calculation of project emissions(12)

𝑃𝐸𝑝 = 𝑃𝐿𝑃𝐽,𝑋,𝑙𝑖𝑛𝑒𝑠,𝑝 × 𝐸𝐹𝐺𝑟𝑖𝑑
𝑁(13)

𝑃𝐿𝑃𝐽,𝑋,𝑙𝑖𝑛𝑒𝑠,𝑝 = ∑ 𝑃𝐿𝑃𝐽,𝑙𝑖𝑛𝑒𝑖,𝑝
𝑖=1

Where
𝑃𝐸𝑝
𝑃𝐿𝑃𝐽,𝑋,𝑙𝑖𝑛𝑒𝑠,𝑝＝ Project emission during the period p (tCO2/p)
Project transmission line loss at transmission lines in the project＝
area X during the period p (MWh/p)＝ CO2 emission factor for grid (tCO2/MWh)
Project transmission line loss at transmission line i during the＝period p (MWh/p)＝ Number of transmission lines in the project area X (-)

𝐸𝐹𝐺𝑟𝑖𝑑
𝑃𝐿𝑃𝐽,𝑙𝑖𝑛𝑒𝑖,𝑝N
𝑝

𝑃𝐿𝑃𝐽,𝑙𝑖𝑛𝑒𝑖,𝑝 = ∑ 𝑃𝐿𝑃𝐽,𝑙𝑖𝑛𝑒𝑖,𝑡 ×
𝑡=0

Where
𝑃𝐿𝑃𝐽,𝑙𝑖𝑛𝑒𝑖,𝑡T
𝑃𝐿𝑃𝐽,𝑙𝑖𝑛𝑒𝑖,𝑡𝑇
× 10−660(14)＝ Project transmission line loss at transmission line i at the time t (W)＝ Measurement interval (min)is calculated based on the calculation formula of EGAT as follows:(15)

𝑃𝐿𝑃𝐽,𝑙𝑖𝑛𝑒𝑖,𝑡 ＝𝑓(𝑃𝑘,𝑖,𝑡, 𝑄𝑘,𝑖,𝑡, 𝑉𝑘,𝑖,𝑡, 𝑉𝑙,𝑖,𝑡, 𝑅𝑖, 𝑋𝑖, 𝐵𝑖 )Where
Pk,i,t=Active power at the bus k of transmission line i at the time t (W)Qk,i,t=Reactive power at the bus k of transmission line i at the time t (var)Vk,i,t=Voltage measured at the bus k of transmission line i at the time t (V)Vl,i,t=Voltage measured at the bus l of transmission line i at the time t (V)Ri=

Resistance of transmission line i (Ω)

Xi=

Reactance of transmission line i (Ω)

Bi=

Susceptance of transmission line i (S)H. Calculation of emissions reductions

8

JCM_TH_AM017_ver01.0
Sectoral scope: 02

(16)
Where
𝐸𝑅𝑝
𝑅𝐸𝑝
𝑃𝐸𝑝

＝ Emission reduction during the period p (tCO2/p)＝ Reference emission during the period p (tCO2/p)＝ Project emission during the period p (tCO2/p)

I. Data and parameters fixed ex ante
The source of each data and parameter fixed ex ante is listed as below.
Parameter

Description of data

𝐸𝐹𝐺𝑟𝑖𝑑CO2 emission factor for grid (tCO2/MWh)

Source[Grid electricity]
The most recent value available
at the time of validation isapplied

and

fixed

for

the

monitoring period thereafter. The
data is sourced from “Grid
Emission

Factor(GEF)

ofThailand”, endorsed by Thailand
Greenhouse Gas Management
Organization, unless otherwise
instructed

by

the

Joint

Committee.
𝑅𝑎𝑡𝑖𝑜𝑚𝑜𝑑𝑒
Ri

Mode value of Ratiok of Vk,i to the baseCalculated

based

on

the

voltage Vbase,i. of transmission line i (-)

procedure described in F.2.

Resistance of transmission line i (Ω)
Calculated by electromagnetics
based

on

the

characteristics
geometry,

configuration
like

tower

conductor

types,

number, phasing and groundcondition of circuits of overheadtransmission line i which are
obtained

from

EGAT.

The

calculations are performed using
a general-purpose calculation
program package.
9

JCM_TH_AM017_ver01.0
Sectoral scope: 02
Xi

Reactance of transmission line i (Ω)

Calculated by electromagnetics
based

on

the

characteristics
geometry,

configuration
like

tower

conductor

types,

number, phasing and groundcondition of circuits of overheadtransmission line i which are
obtained

from

EGAT.

The

calculations are performed using
a general-purpose calculation
program package.
Bi

Susceptance of transmission line i (S)Calculated by electromagnetics
based

on

the

characteristics
geometry,

configuration
like

tower

conductor

types,

number, phasing and groundcondition of circuits of overheadtransmission line i which are
obtained

from

EGAT.

The

calculations are performed using
a general-purpose calculation
program package.
T

Measurement interval (min)Predeterminedmeasurement

interval
Vbase,iBase voltage of transmission line i (V)Specification oftransmission

line i
VRE,k,iReference voltage at the bus k of

Calculated

based

transmission line i (V)procedure described in F.2.

History of the document
Version
01.0

Date
17 June 2022

Contents revisedElectronic decision by the Joint Committee
Initial approval.

10

on

the