LOAD FLOW STUDY
Level 1
Mohamad Arifin, ST, IPM
Electrical Engineer
OBJECTION OF LOAD FLOW STUDY
Why Must Do The Load Flow Study:
1. Sizing Capacity of Generator, Transformer,
Busbar & Cable/ Busduct, Capacitor.
2. Transformer Tap Setting
3. Analysis Drop Voltage at Bus Bar/
Switchgear & Load
4. Profile Power Flow, Current Flow, Power
Factor.
CONCLUSION OF LOAD FLOW STUDY
Conclusion of Load Flow Study:
1. Bus Voltages are Within Acceptable Limits
(+/- 10% Vnominal refer to IEC 60038 or
Contract specification)
2. Power & Current Flows Do Not Exceed the
Maximum Ratings (90% rating)
3. System MW & Mvar Losses are Determined
4. Circulating Mvar Flows are Eliminated
ETAP SOFTWARE FLOW
Basic Engineering
Input Data
Output
Etap Software
Etap’s software give facility for engineer to execute the load flow study with many
configuration. For correct Output calculation, we must know what the data input on
Load Flow Study should be inputted.
LOAD CATEGORY ON LOAD FLOW STUDY
• Load Category:
1. Constant Power Load: Induction Motor,
Synchronous Motor, Lump Load (100%
motor), Charger & UPS
2. Constant Impedance Load: Static Load,
Lump Load (100% static), Capacitor &
Harmonic Filter, MOV
3. Constant Current Load: for DC Study
Purpose
LumpLoad : to model load which is various i.e package, city consument loads which
is impossible to make a detail models
LOAD CATEGORY ON LOAD FLOW STUDY
LOAD CATEGORY ON LOAD FLOW STUDY
LOAD CATEGORY ON LOAD FLOW STUDY
LOAD CATEGORY ON LOAD FLOW STUDY
CALCULATION METHODE ON LOAD FLOW
Calculation Methods:
1. Newton Raphson
2. Gauss-Seidel
3. Fast-Decoupled
DATA INPUT REQUIRED ON LOAD FLOW STUDY
A. Switchgear/MCC
1. Nominal kV
2. %V and Angle (when Initial Condition
is set to use Bus Voltages)
3. Load Diversity Factor (when the
Loading option is set to use
Diversity Factor)
DATA INPUT REQUIRED ON LOAD FLOW STUDY
4. Continuous Load
DATA INPUT REQUIRED ON LOAD FLOW STUDY
A. Generator
1. Operating mode (Swing,
Voltage Control, Mvar
Control, PF Control
DATA INPUT REQUIRED ON LOAD FLOW STUDY
Mode Generator
1. Swing/ Isochronous : Any change on the load operation, voltage generator will
maintain on voltage nominal but other parameter of output generator will follow
and change as load server.
2. Droop:
a. Voltage Control
Generator will maintain so that voltage and MW of output generator fixed
even any change on the load operation
b. Mvar Control
Generator will maintain so that MW and Mvar of output generator fixed even
any change on the load operation
c. PF Control
Generator will maintain so that MW and PF of output generator fixed even
any change on the load operation
DATA INPUT REQUIRED ON LOAD FLOW STUDY
2. kW, kV, %PF, % eff
3. Prime mover rating
DATA INPUT REQUIRED ON LOAD FLOW STUDY
4. Generator Capability Curve
DATA INPUT REQUIRED ON LOAD FLOW STUDY
Generator Capability
Curve of Kato
DATA INPUT REQUIRED ON LOAD FLOW STUDY
B. Transformer Data
1.
2.
Voltage rating
Power Rating
Basic Theory:
𝐼=
𝑆
3𝑥𝑉
Where,
I = Service Current (A)
S= Apparent Power (VA)
V= Service Voltage (V)
DATA INPUT REQUIRED ON LOAD FLOW STUDY
3. Impedance (Positive & Zero), X/R.
DATA INPUT REQUIRED ON LOAD FLOW STUDY
Data Trasformer
LOAD CATEGORY ON LOAD FLOW STUDY
C. Induction Motor
1.
2.
kW, kV
PF, Eff at 50%, 75% & 100%
Basic Theory:
𝐼=
𝑃
3𝑥𝑉𝑥𝐶𝑜𝑠∅𝑥𝜂
Where,
𝐼 = Service Current (A)
P= Active Power (W)
V= Service Voltage (V)
DATA INPUT REQUIRED ON LOAD FLOW STUDY
Data motor ABB
DATA INPUT REQUIRED ON LOAD FLOW STUDY
D. Static Load
1. kV, kVA, %PF
Basic Theory:
𝐼=
𝑆
3𝑥𝑉𝑥𝐶𝑜𝑠∅
Where,
I = Service Current (A)
S= Apparent Power (VA)
V= Service Voltage (V)
DATA INPUT REQUIRED ON LOAD FLOW STUDY
E. Lump Load
1. kVA, %PF
LOAD FLOW STUDY CASE
Tools Load Flow
A. Info
LOAD FLOW STUDY CASE
C. Loading
LOAD FLOW STUDY CASE
• Adjusment
LOAD FLOW STUDY CASE
• Alert