The document discusses parameters and criteria for assessing connecting requests to an electrical network in NEPLAN software. Key parameters include nominal voltage, repeat rate, limits for voltage change, flicker, harmonics, and reactive power. The assessment is based on calculations of short-circuit power, installation current, voltage changes, flicker intensity, harmonic emissions, and more. Results are compared to technical rules to evaluate the connection request.

1. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-1
Assessment of connecting
requests
Parameters
One device/installation to be assessed is defined in the diagram as a common
network element (see Section „Elements-Data input“). The device or installation
data are entered in different dialogs. The user can start the assessment In the
dialog „Connecting request“. The following parameters must be set prior to the
assessment:
Evaluation according to the following criteria
Voltage change The assessment is based on voltage changes.
Voltage rise The assessment is based on the voltage rise. One of the
options „Generation station“ or „Temporary return feed“ in
the tab „Connection“ must be activated.
Flicker The assessment is based on the flicker. The option
„Constant load change “ in the „ Connection“ dialog must be
activated.
Harmonics The assessment is based on the harmonics. The option
„Operation with converter “ in the „Connection“ dialog must
be activated.
Evaluation according to the following criteria
Reactive
compensation
The properties of the reactive power compensation are
calculated. These properties are irrelevant for the
assessment.
Commutation The relevant data for the commutation are calculated. This
data are irrelevant for the assessment.
Measurements If measurements are defined, they will get compared against
the harmonic limit values. The measurements are considered
for the assessment of the harmonics.
Voltage
unbalance
If the connection is not symmetric (3-phase) then the
assessment is based on the voltage unbalance criteria.
Connection

2. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-2
Un Nominal voltage of the supply terminal or point of common
coupling in kV.
Repeat rate The repeat rate that is relevant for the assessment in 1/min
(see under „Repeat rate“ in the „Connection“ dialog or
„Device type-Repeat rate“).
Assessment at If the point of common coupling is different than the supply
terminal (see „Connecting request”> “Connection “ dialog),
then the assessment can be done at the point of common
coupling or at the supply terminal. Usually the supply
terminal is considered since the point of common coupling
and the supply terminal coincide.
Limits for Voltage change/flicker
dLim Limit for the relative voltage change. This limit depends on
the nominal voltage at the point of assessment and on the
number of load changes r.
Form factor Form factor for the conversion of special forms of voltage
change characteristics in flicker-equivalent voltage jumps.
Short-term Flicker
limit Pst
Limit for the short-term flicker.
Long-term Flicker
Limit Plt
Limit for the long-term flicker.
Pst calculation
with analytical
method
If checked, then the flicker intensity is calculated with the
analytical method (R: Frequency factor, F: Form factor)
2.3
1
min%
365.0 −⋅⋅⋅⋅= rdRFPst
Summation
coefficient alpha
The summation coefficient alpha lies usually between 1 and
4 and is used for the superposition (summation) of several
flicker sources Pst i or Plt i.
α
α
∑=
=
n
i
istst PP
1
Limits for Generation units
dLim Limit for the relative voltage rise. This limit depends on the
nominal voltage at the point of assessment.
Delta U Limit for the relative voltage rise for all generation units. The
limit depends on the nominal voltage at the point of
assessment.

3. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-3
Pressing the buttons „Set standard values“ sets the above parameters to their
standard values according to the D-A-CH-CZ technical rules.

4. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-4
Assessment
The assessment is based on certain criteria and technical rules. The theoretical
aspects are beyond the scope of this manual.
Calculation of the short-circuit power SkV
The calculation of the short-circuit power SkV and the network impedance Zn
follows the same concept as the short-circuit calculation based on the
superposition method (not according to the IEC60909), with the difference that
the min. short-circuit power is used for the network feeder.
Calculation of the installation current
The installation current Ia is calculated from the installation apparent power Sa
and the nominal voltage Un at the supply terminal:
Connection: phase-to-neutral:
U
Sa
Ia = with U=Un/√3
Connection: phase-to-phase:
U
Sa
Ia
⋅
=
3
with U=Un
Connection: 3-phase symmetrical:
U
Sa
Ia
⋅
=
3
with U=Un
If the option “Uc” was activated in the dialog „Connection“ then U=Uc.

5. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-5
Assessment based on voltage changes/flicker
The relative voltage change is calculated with:
( )ln
Skv
Sa
d ϕψ −⋅= cos
with the input data:
• Sa: installation power (Dialog „Connection“)
• φl: angle calculated from cos(φ)Load (Input in dialog „Device type”>Load angle)
and the calculated variables:
• Skv: short-circuit power at the supply terminal or point of common coupling
• Ψn: network –impedance angle at the supply terminal or point of common
coupling.
In case of a phase-to-neutral or phase-to-phase connection the corresponding
formulas in the technical rules are used. If the point of common coupling is at the
high-voltage side of a transformer then the transformer vector group will be
considered. The transformer must be entered in the diagram immediately before
the element “Connecting request” or the option “own transformer” must be
activated in the dialog. In the last case the vector group must be entered as well.
Calculation of the flicker intensity with the analytical method
The following equation is used:
2.3
1
min%
365.0 −⋅⋅⋅⋅= rdRFPst
with:
• F: Form factor (dialog „Assessment of connection“)
• R: Frequency factor (dialog „Assessment of connection“)
• r: Repeat rate in 1/min (dialog „Connection“)
and the calculated value:
• d: Relative voltage change in %
Superposition (summation) of several flicker sources
The following equation is used:

6. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-6
α
α
∑=
=
n
i
istst PP
1
with:
• α: Summation coefficient alpha (dialog „Assessment of connection“)
The single flicker sources (components of the installation) can be entered in the
dialog „Connection“ > Button „Sa-Calculation“ > „Single Components“.
Assessment based on harmonics
The parameter „Operation with converter“ in the „Connection“ dialog must be
activated. The assessment is based on the D-A-CH-CZ technical rules. The limits
for the emissions of the harmonic currents are calculated and the harmonic load
content is evaluated:
SOS = 0.5*SGr.1 + SGr.2
SGr.1: Apparent power of the harmonic sources of Group1 (low emission)
SGr.2: Apparent power of the harmonic sources of Group2 (high emission)
The values SGr.1 and SGr.1 are entered in the dialog „Device type“. They can be
calculated if the single components of the installation were defined (see
„Connection“ > „Sa-calculation“ > “Single components”).
Assessment of the measurements
The current and voltage measurements defined in the dialog „Other
Installations/Measurements“ get compared against the emission limits of the
individual harmonic currents and harmonic voltages and then evaluated.
Assessment of the commutation
It is essential to take certain measures in order to keep the depth of the
commutation notches low. The relative short-circuit voltage of the commutation
reactance is calculated:
Vk
Strr
Kom
Komk
S
S
1
d
1
2
3
u ⋅








−⋅=
with

7. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-7
• dkom: relative depth of a commutation notch (LV: 0.1; MV: 0.05)
• SrStr: apparent power Sr of converter
• SkV: short-circuit power at the supply terminal.
The inductance is:
Strr
2
KomkKom
S
U
u
f2
1
L ⋅⋅
⋅π⋅
=
with
• f: network frequency
• U: nominal voltage at the supply terminal
If there is a transformer between the installation (device) and the network, then
the remaining reactance LD is calculated from:








⋅−⋅⋅
⋅π⋅
=
Tr
2
Tk
Strr
2
KomkD
S
U
u
S
U
u
f2
1
L
with
• SrT: nominal power of the transformer
• ukT: short-circuit voltage of the transformer
• U: network nominal voltage at the supply terminal
The transformer can be entered directly in the diagram or in the dialog
“Connection” by activating the option “own transformer”.
Assessment of a temporary return feed
When return feeds are present, as e.g. in brake drives, the assessment will be
based n voltage change:
( )ln
Skv
Sret
d ϕψ −⋅= cos
with the input data:
• Sret: power fed to the network (dialog „Connection“)
• φl: angle from cos(φ)Load (input in dialog „Device-type >Load angle)
and the calculated values:
• Skv: Short-circuit power at the point of common coupling or the supply
terminal

8. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-8
• Ψn: Network-impedance angle at the point of common coupling or the supply
terminal
Assessment of a generating unit
The relative voltage rise and voltage change are calculated as in the following:
- maximum apparent power SnEmax
Wind energy: minmax 10p
PnE
SnE ⋅=
λ
Non-Wind energy: SnESnE =max
- Voltage rise duA
Wind energy: ( )GWnp
Skv
PnE
duA ϕψ
λ
−⋅⋅
⋅
= cos1min
Non-Wind energy: ( )GWn
Skv
SnE
duA ϕψ −⋅= cos
- Connection-related voltage change dmax (“start”)
Wind energy: ( )GWnmomp
Skv
PnE
d ϕψ
λ
−⋅⋅
⋅
= cosmax
Non-Wind energy: ( )Sn
Skv
Ss
d ϕψ −⋅= cosmax
- Connection-related voltage change dzu (“switching”)
Wind energy: ( )GWnaktzu ki
Skv
PnE
d ϕψ
λ
−⋅⋅
⋅
= cos
Non-Wind energy: ( )zn
Skv
Sz
dzu ϕψ −⋅= cos
with the input data:
• PnE, SnE: active- and apparent power of the generation station

9. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-9
• Ss: Power change at start-up of the generation station
• Sz: Power change at switching of the generation station
• λ: power factor at max. power
• p10min, p1min, pmom: maxima of active power (10 min- or 1 min-interval,
instantaneous value)
• kimax: max. switched current factor
• kiakt: system dependent switched current factor
• φGW: angle from cos(φ) of the fundamental wave
• φl: angle from cos(φ)Last (input in dialog „Device-type“ > Load angle)
• φs: angle from cos(φ)start
• φz: angle from cos(φ)switch
and the calculated values:
• Skv: short-circuit power at the point of common coupling
• Ψn: Network impedance angle at the point of common coupling
One flicker-relevant generating unit at one point of common-coupling
( )fn
Vk
Er
lt
S
S
cP ϕψ −⋅⋅= cos
with the input data:
c: the station flicker coefficient
φf: flicker-relevant phase angle
Several One flicker-relevant generating units at one or more points of
common-coupling
In this case the summation is formed:
∑=
=
n
1i
2
iltlt
PP
The individual Plt i-values can be defined in the dialog „Other
installations/Measurements“. Before the summation the short-circuit power at the
different points of common coupling are calculated and considered:
kVk
jVk
jjltjkltkVkjVk
S
S
PP:SS ⋅=p

10. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-10
jjltjkltkVkjVk
PP:SS =≥
SkVj: short-circuit power at point of common coupling j
SkVk: short-circuit power at point of common coupling k

11. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-11
In case of n identical units the summation is:
Vk
iEr
iltlt
S
S
cnPnP ⋅⋅=⋅=
The number n can be entered in the dialog „Connection“.

12. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-12
Results of an assessment
After the assessment a dialog will appear with information on whether the request
was accepted (“Permissible”) or not (“Measures”). The assessment is based on
the criteria selected by the user. Please note that the choice of the relevant
criteria is in the responsibility of the user.
Data sheet
All input data are listed in tables. Explanations and comments on those are found
in the section „Element Data Input (Connecting request)“.
Overall assessment
The results of the assessment are listed. These are:
Assessment
Point of common coupling/Supply
terminal
The network node of connection
(supply node or point of common
coupling).
Nominal voltage Un Nominal voltage in kV at the supply
terminal
Short-circuit power SkV Short-circuit power at the supply
terminal
Maximum power Sa Maximum power change of the
installation in kVA
Installation current Ia Max. current change of the installation
current in A.
Repeat rate Repeat rate in 1/min for load changes.
Connection Overall assessment: “Permissible” or
“Measures”.
Voltage changes
Relative voltage change d (supply
terminal)
Relative voltage change at the supply
terminal.
Relative voltage change d (point of Relative voltage change at the point of

13. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-13
common coupling) common coupling (the assessment
must be at the point of common
coupling)
Relative voltage change d (limit) Limit value for the relative voltage
change at the point of assessment
(supply terminal or point of common
coupling).
Connection Assessment based on voltage
changes: “Permissible” or “Measures”.
Flicker
Relative voltage change d (supply
terminal)
Relative voltage change at the supply
terminal.
Relative voltage change d (point of
common coupling)
Relative voltage change at the point of
common coupling (the assessment
must be at the point of common
coupling)
Relative voltage change d (limit) Limit value for the relative voltage
change at the point of assessment
(supply terminal or point of common
coupling).
Short-time flicker intensity Pst (supply
terminal)
Calculated short-term flicker intensity
Plt at the supply terminal
Short-term flicker intensity Pst (limit) Limit value for the short-term flicker
intensity Plt (supply terminal or point
of common coupling).
Long-term flicker intensity Plt (supply
terminal)
Calculated long-term flicker intensity
Plt at the supply terminal.
Long-term flicker intensity Plt (limit) Limit value for the long-term flicker
intensity Plt (supply terminal or point
of common coupling).
Maximum permissible power Maximum permissible installation
power in kVA based on the value
above (limit value for the relative
voltage change).
Maximum permissible rated motor
current (Ia/Ir: constant)
In case of a connection of a motor the
max. permissible nominal current is
entered. The calculation is based also
on the limit value above (limit for
relative voltage change) and under the
assumption that the ratio start. current

14. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-14
to rated current (Ia/Ir) is constant.
Connection Assessment based on flicker:
“Permissible” or “Measures”.
Voltage unbalance
Voltage unbalance factor Calculated voltage unbalance factor in
case of an unsymmetrical connection
of the device. The limit value for the
voltage unbalance is 0.7%.
Connection Assessment based on voltage
unbalance: “Permissible” or
“Measures”.
Harmonics
Ratio SkV/Sa Ratio of the short-circuit power to the
installation power.
Ratio SkV/Sa (limit) Ratio of the short-circuit power to the
installation power (limit).
Harmonic load of the installation Harmonic load content of the
installation
Harmonic load of the installation (limit) Harmonic load content of the
installation (limit)
Emission limit for the totality of all
harmonic currents THDiA
Permissible total harmonic content of
the installation THDiA
Connection Assessment based on harmonics:
“Permissible” or “Measures”.
Evaluation of harmonics in chart and table form
The following values can be displayed in chart or table form by pressing the
corresponding button:
• Emission limits for harmonic current (table or chart)
• Flicker-limit curve with the relative voltage change of the installation shown
• Chart for the assessment of the harmonic load content (depicted in chart).
Measurements/Harmonics
Critical harmonic current Critical harmonic current in the
entered series of measurements.
Harmonics of the critical harmonic
current
Harmonics of the critical harmonic
current in the entered series of

15. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-15
current measurements.
Emission limit of the critical harmonic
current
Emission limit of the critical harmonic
current in the series of measurements
entered.
Totality of all harmonic currents THDi Totality of all harmonic currents THDi
in the series of measurements
entered.
Critical harmonic voltage Critical harmonic voltage in the series
of measurements entered.
Harmonics of the critical harmonic
voltage
Harmonics of the critical harmonic
voltage in the series of measurements
entered.
Emission limit of the critical harmonic
voltage
Emission limit of the critical harmonic
voltage in the series of measurements
entered.
Totality of all harmonic voltages THDu Totality of all harmonic voltages THDu
for the series of measurements
entered.
Connection Assessment based on measurements:
“Permissible” or “Measures”.
The measurements get compared
against the harmonic limits.
The measurements for harmonic voltages and currents are entered in the dialog
„Other installations/ Measurements“. These measurements get compared against
the calculated harmonic limits for current and THDi or voltage and THDu.
Commutation
Required relative short-circuit voltage uk
com
Required relative short-circuit voltage
uk com
Required inductance L com Required inductance Lk kom
Remaining inductance L D Remaining inductance L D, if the
inductance of the transformer gets
subtracted from the required
inductance Lk kom. The transformer
must be directly connected with the
element “Connecting request” in the
diagram or the option “own
transformer” must be activated in the
dialog “Connection”.

16. Assessment of connecting requests
Manual NEPLAN
/D-A-CH AG-16
Reactive power compensation
Resonance frequency System resonance frequency in Hz
when considering compensation.
Maximum impedance for minimum
absorption effect
Maximum impedance for minimum
absorption effect with detuned
compensation.
Voltage rise
Maximum apparent power of the
generating station
Maximum apparent power of the
generating station.
Relative voltage rise Relative voltage rise.
Relative voltage rise (limit) Relative voltage rise (limit).
Relative voltage rise (maximum) Relative voltage rise (maximum).
Relative voltage rise (switch) Relative voltage rise (switch).
Relative voltage rise (limit) Relative voltage rise (limit).
Connection Assessment based on the voltage
rise: “Permissible” or “Measures”.