Assessment of network disturbances d a-ch-cz

Assessment of connecting requests

Manual NEPLAN/D-A-CH AG-1


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



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 1min%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

iistst 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.



Pressing the buttons „Set standard values“ sets the above parameters to their standard values according to the D-A-CH-CZ technical rules.



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:

USaIa = with U=Un/√3

Connection: phase-to-phase:

USaIa

⋅=

3 with U=Un

Connection: 3-phase symmetrical:

USaIa

⋅=

3 with U=Un

If the option “Uc” was activated in the dialog „Connection“ then U=Uc.



Assessment based on voltage changes/flicker The relative voltage change is calculated with:

( )lnSkvSad 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 1min%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:



α α∑=

=n

iistst 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 SS

1d1

23u ⋅

−⋅=

with



• 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 SUu

f21L ⋅⋅

⋅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 SUu

SUu

f21L

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:

( )lnSkvSretd 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



• 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 10pPnESnE ⋅=λ

Non-Wind energy: SnESnE =max

- Voltage rise duA

Wind energy: ( )GWnpSkvPnEduA ϕψ

λ−⋅⋅

⋅= cos1min

Non-Wind energy: ( )GWnSkvSnEduA ϕψ −⋅= cos

- Connection-related voltage change dmax (“start”)

Wind energy: ( )GWnmompSkvPnEd ϕψ

λ−⋅⋅

⋅= cosmax

Non-Wind energy: ( )SnSkvSsd ϕψ −⋅= cosmax

- Connection-related voltage change dzu (“switching”)

Wind energy: ( )GWnaktzu kiSkvPnEd ϕψ

λ−⋅⋅

⋅= cos

Non-Wind energy: ( )znSkvSzdzu ϕψ −⋅= cos

with the input data: • PnE, SnE: active- and apparent power of the generation station



• 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

( )fnVk

Erlt S

ScP 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

2iltlt 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

jVkjjltjkltkVkjVk S

SPP:SS ⋅=p



jjltjkltkVkjVk PP:SS =≥

SkVj: short-circuit power at point of common coupling j SkVk: short-circuit power at point of common coupling k



In case of n identical units the summation is:

Vk

iEriltlt S

ScnPnP ⋅⋅=⋅=

The number n can be entered in the dialog „Connection“.



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



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



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



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”.



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”.

Documents

Assessment of network disturbances d a-ch-cz