1. Distribution Code Public Consultation – DCRP/19/03/PC – Stage 3 Worked Example– Stakeholder Engagement Dissemination Event
Name Forooz Ghassemi (National Grid)
Company Energy Networks Association – Code Administrator – Distribution Code of Great Britain
Date 1st April 2019

2. Content A fictitious test network One connection Harmonic limits
Two concurrent connections at the same node
Two concurrent connection at different nodes
Harmonic limits for second connection
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

3. Test network A five bus network
A 800 MW connection at Node X is assessed
Transfer coefficients from Node X to other nodes are calculated from the harmonic model
Different scenarios, winter peak, summer mean, outages are considered
Transfer coefficients are the highest in all study cases
Background harmonic levels are obtained by measurement
Assume =1.4 for the harmonic order under study and the Planning Level is 2%
From To
Transfer coefficient X Y 2 A
0.8 B 3 C
1.5
Node
Vbg (%) X
0.5 Y
1.0 A
1.5 B
1.2 C
0.25
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

4. First connection-calculate the headrooms
The harmonic headroom at the PCC (Node X):
H X = − =1.79
For Node Y, the headroom is calculated and transferred to Node X:
H Y−X = − =0.71
The same is applied for other nodes
Node
Headroom (%) HX
1.79
HY-X
0.71
HA-X
1.14
HB-X
0.41
HC-X
1.28
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

5. Nominal phase–phase voltage (V)
Calculate the apportionment factor
For an 800 MW connection at 400 kV:
=2000
and k=0.4
From apportionment curve; M=0.532
Nominal phase–phase voltage (V) kV
β value
132 < V < 275
1000
275
1500
400
2000
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

6. Total Harmonic Voltage Emission Limits ( V Limit−Total h )
Limits for the first connection
0.41 is the lowest, thus the limiting node for the incremental limit is Node B
V Limit−inc h =0.532 × 0.41=0.22%
V Limit−Total h = × =1.21%
V h Limit Change =0.532 × 1.79=0.95%
V h Limit Resonant = α V h Limit Change α – V h Inc α = x – =0.86%
Harmonic order h
Pre-existing background harmonic voltage at the PCC prior to connection of the User’s Equipment
(% of fundamental)
Incremental harmonic Voltage Distortion Limits ( V Limit−inc h ) due to harmonic current/voltage emission at the PCC
Total Harmonic Voltage Emission Limits ( V Limit−Total h ) h
0.5
0.22
1.21
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

7. Two concurrent connection at the same PCC
Assume, following the signing of the first connectee of 800 MVA, the second connection of 2000 MVA applies to connect to Node X
For the second connection at Node X
k= =1.0
From the apportionment curve; M=0.66
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

8. Modification of headroom by the first connection
Headrooms are modified by the impact of first connection
Since the first connection is not yet connected, measurement does not show the impact
The background shall be determined by calculation
It is assumed the harmonic levels rise by the limits of the first connection
The background at Node X rises to the total limit:
H X−2 h = α V PL h α − V Limit−Total−1 h α = − =1.23%
The harmonic headrooms of the other nodes transferred to Node X are modified by the incremental harmonic limit of the first connection
E.g. for example for Node B, the modified transferred headroom is:
H B−pcc−2 h = α H B−pcc−1 h α − V Limit−inc−1 h α = − =0.29%
Node B is still the limiting node
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

9. Notes of transfer coefficients
Connection of the first User plant does not change the transfer coefficients from Node X to other nodes
therefore no further re-calculation of the transfer coefficients is necessary, i.e. the original transfer coefficients are still valid
However, the connection of the first User plant does impact the transfer coefficients from other nodes to Node X
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

10. Total Harmonic Voltage Emission Limits ( V Limit−Total h )
Limits for the second User at Node X
The headrooms are apportioned and the incremental and total limits are calculated
V Limit−inc−2 h =0.66× 0.29=0.19%
V Limit−Total−2 h = × =1.66%
V h Limit Change =0.66 × 1.21=0.80%
Harmonic order h
Pre-existing background harmonic voltage at the PCC prior to connection of the User’s Equipment
(% of fundamental)
Incremental harmonic Voltage Distortion Limits ( V Limit−inc h ) due to harmonic current/voltage emission at the PCC
Total Harmonic Voltage Emission Limits ( V Limit−Total h ) h
1.21
0.19
1.66
V h Limit Resonant = α V h Limit Change α – V h Inc α
= x – =0.72%
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

11. Two connection at different nodes
Consider the second connection at Node Y instead of Node X
The harmonic transfer coefficients from Node X to other nodes are the same as before
The harmonic transfer coefficients from Node Y to other nodes, including Node X should also be obtained from the harmonic model
From To
Transfer coefficient Y X
1.6 A 3 B
1.4 C
1.1
From To
Transfer coefficient X Y 2 A
0.8 B 3 C
1.5
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

12. Impact of the first connection on background
The background harmonic levels at all nodes are impacted by the first connection
Therefore, harmonic headroom at all nodes are modified by the first connection
the background at Node X (first PCC) would be the total limit, i.e. after connection the levels rise to the total limit for the first connection
The remote nodes background increase by the incremental limit for the first connection through the transfer coefficient from Node X to others
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

13. Modification of background of Nodes X and Y
Node X new background
V bg−X−2 h =V Limit−Total−1 h =1.21%
For Node Y the background harmonic level increases using the incremental limit for the first connection through the transfer coefficient from X and Y
V bg−Y−2 h = α V bg−Y h α + G X−Y h × V Limit−inc−X−1 h α = × =1.22%
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

14. Other nodes new backgrounds
V bg−A−2 h = × =1.55%
V bg−B−2 h = × =1.55%
V bg−C−2 h = × =0.48%
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

15. Harmonic headrooms Harmonic headroom at Node Y
H Y−2 = − =1.22%
Harmonic headroom at other nodes
H X−Y− − =0.77%
H A−Y− − =0.28% H B−Y− − =0.60% H C−Y− − =1.64%
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

16. Limit for the second connection at Node Y
The limiting remote node is Node A
The multiplier M is 0.66 (for k=1, M=0.66).
V Limit−inc−2 h =0.66 × 0.28=0.18%
V Limit−Total−2 h = × =1.68%
V h Limit Change =0.66 × 1.22=0.81%
V h Limit Resonant = α V h Limit Change α – V h Inc α = x – =0.74%
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

17. Total Harmonic Voltage Emission Limits ( V Limit−Total h )
Harmonic limit table
Harmonic order h
Pre-existing background harmonic voltage at the PCC prior to connection of the User’s Equipment
(% of fundamental)
Incremental harmonic Voltage Distortion Limits ( V Limit−inc h ) due to harmonic current/voltage emission at the PCC
Total Harmonic Voltage Emission Limits ( V Limit−Total h ) h
1.22
0.18
1.68
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event

18. Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Background
Name Forooz Ghassemi/Simon Scarbro
Company National Grid/Western Power Distribution
Date 1st April 2019

19. Closing Second Stakeholder Engagement – Glasgow 10th April 09:30-16:00
Consultation Next Steps
A comprehensive consultation pack with further details can be downloaded from the Distribution Code Website using the following link- consultations/ and opening consultation tab DCRP/19/03/PC.
Responses to this consultation should be sent to the Distribution Code Administrator at by 17:00 on 19 April 2019 on the pro-forma provided in the pack. Responses received after this date may not be considered.
Distribution Code Public Consultation – DCRP/19/03/PC – Engineering Recommendation (EREC) G5 Issue 5 (2019) – Stakeholder Engagement Dissemination Event