1) The document discusses grid code compliance testing and certification requirements for renewable energy projects in Vietnam. It outlines Vietnam's grid code requirements related to reactive power capability, fault ride through, frequency and voltage control, harmonics limits, and flicker emission. 2) Testing must be performed by ISO/IEC 17025 accredited laboratories, and test reports submitted to certification bodies for assessment of compliance with the Vietnam grid code. Fault ride through voltage levels must follow the code's profile, with the unit remaining connected during and after two consecutive fault tests. 3) UL provides grid code compliance testing and certification services to help renewable energy projects meet the requirements of countries' grid codes.

1. © 2023 UL LLC. All rights reserved.
UL Renewables
Grid Code Compliance – Importance and
Best Practices
Nivedh BS
Business Manager – Wind TIC, Asia Pacific
ULS22CS458635
Hanoi
Feb 24th 2023

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9. Grid Code Compliance
Testing and Certification
9

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Current Status Worldwide:
International
Standards/Guidelines
National
Procedures/Guidelines
Germany
FGW TR3 (Testing)
FGW TR8 (Certification)
UK
ENA Engineering
Recommendation
G99
Spain
NTS: Standard for
monitoring the
compliance of PGMT
In countries where no
special testing procedure
exists, the general rule is to
use IEC 61400-21-1 ed. 1as
a guide
China
• GB/T 36995-2018
(Voltage Fault Ride
Through)
• GB/T 20320-2013 / IEC
61400-21, 2008 (PQ)
European Commision
European Network Code
for Connection of
Generators (RfG)
US
IEEE 1547.1, IEEE
519
India
Technical Standards for
Connectivity to the Grid
Regulations 2007 /
Amendment Regulations
2013 & 2019

11. 11
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Vietnam Grid Code Requirements:
Areas
Power
Quality
Fault
Ride
Through
Control
Require
ments
Grid
Protection
Reactive Power Capability
 Wind and PV plants must have the capability of
injecting or absorbing reactive power
 If power plant generates an active power capacity
greater or equal to 20% of rated power, then the
power plant must be capable of Continuously
adjust reactive power over a power factor range of
0.95 under-excited to 0.95 over-excited mode.
Fault Ride Through
Wind and PV farms must remain connected to the grid without tripping
of any generating units and withstand voltage dip and swell
 Low Voltage Ride Through (LVRT):
- for Voltage level of 0 p.u.
PGU shall withstand minimum of 0.15 s
- for Voltage level [U] from 0.3 p.u. to 0.9 p.u , the minimum
withstand time (Tmin) will be calculated by
formula (Tmin = 4*U - 0.6) in sec.
- for Voltage between 0.9 p.u. to 1.1 p.u. PGU must maintain
continous power generation
 High Voltage Ride Through (HVRT):
- for Voltage swell of 1.10 p.u. to 1.15 p.u. and fault duration is 3s
- for Voltage swell of 1.15 p.u. to 1.2 p.u. and fault duration is 0.5s
Grid protection
Reliable fault detection

12. 12
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Fault Ride Through Requirements:

13. 13
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Vietnam Grid Code Requirements:
Areas
Power
Quality
Fault
Ride
Through
Control
Require
ments
Grid
Protection
Frequency Range
Wind and PV plants should be able to generate active power in the
frequency range of 49 Hz to 51 Hz as high capacity as possible
according to available energy sources (wind potential or solar
insolation)
 Frequency control
When frequency of electrical system exceeds 51 Hz, Wind
and PV plants should decrease active power as provided by
the following formula,
ΔP = 20 X Pm X
51.0 − 𝑓𝑛
50
where,
ΔP is active power reduction,
Pm is Active power at the time prior to the power reduction
fn is frequency before conducting power decrease (Hz)
The factor 20 is equivalent to the droop of 5% of Pm
Frequency range of the electrical
system
Minimal time for maintaining power
generation
47.5 Hz to 48.0 Hz 10 mins
48 Hz to 49 Hz 30 mins
49 Hz to 51 Hz continuous generation
51 Hz to 51.5 Hz 30 mins
51.1 Hz to 52 Hz 1 min

14. 14
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Vietnam Grid Code Requirements:
Areas
Power
Quality
Fault
Ride
Through
Control
Require
ments
Grid
Protection
Active power control
 Minimum requirement of ramp rate limit is 10% Pn / min
Voltage control
 In case the voltage at PCC falls within the range of ±10% Un
then power plant should be able to adjust the voltage with an
accuracy not more than ± 0.5% nominal voltage within the
permissible working band of generator within 2 minutes of
time.
Harmonics limit
 The requirements of wind and PV farms at connection point
with respect to the harmonics at connections points as
following,
1. THD should not exceed 3% (in % of nominal voltage)
2. THC should not exceed 5% (in % of nominal voltage)
Flicker emission
 During the normal operation, flicker emission at MV and LV
connection points should not exceed the limits as stipulated
below,
1. Pst,95% = 1.0
2. Plt,95% = 0.8

15. 15
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Assessment of compliance with Vietnam Grid code:
1. Testing must be performed by laboratories accredited according to ISO/IEC 17025
2. A full Test Report according to Vietnam Grid code should be submitted for assessment to the Certification
Bodies, including detailed results and graphs
3. FRT voltage levels to follow the profile - the unit shall remain connected during and after the faults for two
consecutive tests

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