Control of network consistency

 

Constants

 

A description of the criteria that exists for some of the controls.

The values described here can if requested be read from an external configuration file. The use of each constant can be seen in the descriptions of the controls below.

 

Exceptions

If there is a service conductor and a calculation length of > 0.9 and < 1.1, and no conductor label exists, then no additional control will be done of the service conductor. The reason is to avoid creating “unnecessary” error-printouts.

 

Constants which are included in the controls below

MAX_PROC_EMTY = 0.1;

MIN_PROC_EMTY = 0.0001;

MAX_PROC_LOADT = 0.1;

MIN_PROC_LOADT = 0.001;

UK_UR_MAXFACT = 40;

MAX_RATED_VOLTFACT = 2;

MIN_RATED_VOLTFACT = 0.5;

MIN_CABLE_LNG = 1.0;

SMALL_CABLE_RX = 0.01;

FACT_CABLE_RX = 40.;

VK1 = 0.00025;

VK2 = 0.03;

LOAD_TEST = 0.6

 

Control description

 

The code: “#_#XX” is a unique “key” for every type of control.

 

Test 1. (#_#1)

Wrong transformer in the sub-station. The transformer is not consistent. A serious error in the transformer-object, for instance only one winding for a two-winding transformer, and other serious formal errors in the transformer-object.

 

Test 2. (#_#2)

A winding relation is missing. There is no winding relation component in the transformer object, with the result that Ur%, Uk% etc. cannot be defined.

 

Test 3. (#_#3)

A faulty winding relation. Concerns object ID for windings. A winding-relation exists, but it’s defined in a wrong way. Either the internal object ID is missing in the winding relation, or the internal object-ID as such is wrong.

 

Test 4. (#_#4)  

Faulty / missing rated voltage for winding with the system voltage for: xx kV. Either rated voltage is missing for a winding, or it has been set to a too low value < 0.05 kV.

 

Test 5. (#_#5)

Too large difference between system voltage for : xx kV and rated voltage for: yy kV. An error will be the result if xx / yy > 1.5 or if xx / yy < 0.75.

 

Test 6. (#_#6)

Rated power = 0 kVA for transformer. Rated power has not been set. The rated power can be searched from both the winding objects  and the winding relation.

 

Test 7. (#_#7)

Too low rated power: xx 0 “kVA for transformer. Rated power exists, but is too low < 5 kVA.

 

Test 8. (#_#8) (Information)

No load losses: xx W > “ + yy % of the rated power. The test is performed according to: no-load-losses / rated power > MAX_PROC_EMTY.

 

Test 9. (#_#9) (Information)

No-load-losses: xx W < “ + yy % of the rated power. The test is performed according to: no-load-losses / rated power < MIN_PROC_EMTY.

 

Test 10. (#_#10) (Information)

Load-losses: xx W < “ + yy % of the rated power. The test is performed according to: load-losses / rated power > MAX_PROC_LOADT.

 

Test 11. (#_#11) (Information)

Load-losses: xx W < “ + yy % of the rated power. The test is performed according to: load-losses / rated power < MIN_PROC_LOADT.

 

Test 12. (#_#12)

Uk% and/or Ur% cannot be obtained for transformer. Uk% or Ur% is missing, or cannot be derived. Comments: If Uk% is missing but Ur% and Ux% exists or can be derived, then Uk% is calculated from Ur% and Ux%. If Ur% cannot be derived from Uk%, and Ux%, then Ur% will be calculated from rated power and load losses if the load losses have been set.

 

Test 13. (#_#13)

Uk% and/or Ur% erroneous for transformer. Uk% and Ur% are set or can be derived from other data, but is wrong. When Ur% >= Uk%.

 

Test 14. (#_#14) (Warning)

Uk% or Ur% can be faulty for transformer. A warning is the result when (Uk% / Ur%) > UK_UR_MAXFACT

 

Test 15. (#_#15)  (Warning

Tap changer or actual setting for the tap changer can be wrong. A warning is the result when:

1.Obtained actual transformer ratio receives a too large or a too small value compared to the documented max and min values for the tap changer.

2.There is a too large deviation between actual transformer ratio and the rated voltage (system voltage / actual rated voltage) > MAX_RATED_VOLTFACT or (system voltage / actual rated voltage) < MIN_RATED_VOLTFACT

 

Test 16. (#_#16)

Both measured length and graphical length = 0

 

Test 17. (#_#17)

Length for calculation is too short xx.xx m

The test is performed according to: Length to the calculation < MIN_CABLE_LNG

 

Test 18. (#_#18)

Resistance and/or inductance = 0.0 Cable

Faulty values in the code-list.

 

Test 19. (#_#19) (Warning)

Small values for the resistance and/or inductance for a conductor

The test is performed according to: resistance < SMALL_CABLE_RX
or inductance < SMALL_CABLE_RX

 

Test 20. (#_#20) (Warning)

To large numeric ratio between resistance and inductance for  Cable.

The test is performed according to: resistance / inductance > FACT_CABLE_RX or inductance / resistance > FACT_CABLE_RX

 

Test 21. (#_#21) (Warning)

A neutral conductor exists but resistance is missing for Cable.

Faulty code list values.

 

Test 22. (#_#22)

Cable label is missing

 

Test 23. (#_#23)

The number of obtained windings does not match the number of anticipated windings.

Faulty transformer.

 

Test 24. (#_#24)

Load calculation performed with load-level: XX %

If the load-calculation could not be performed correctly with normal load-level (100%) the load-level will be lowered in steps of 15% until the load flow calculation converges or that the load level < 5%. A printout is only presented if the load flow calculation was successful with any of the lowered load levels. If the load flow calculation is successful with 100% load level no printout will be presented.

 

Test 25. (#_#25)

Approved Velander record could not be identified

Correct Velander constants could not be identified for delivery point with energy load.

If k1 = 0 then the test will be performed with k1 = VK1.

If k2 = 0 then the test will be performed with k2 = VK2

 

Test 26. (#_#26) (Information)

High Velander power / load current: xxx kW yy A compared to customer fuse: zz A injected energy: wwww kWh

The conditions for test are:
1) approved Velander constants
2) energy load and
3) a customer fuse.

First the power is calculated from energy load and Velander formula. The power is then recalculated to current. The current is reduced with a multiplication of LOAD_TEST. The obtained current is tested against the customer fuse. Information if current > customer fuse.

 

Test 27. (#_#27)

Faulty transformer winding found, parent object is missing. The substation comes from guesswork!

A serious error in the transformer object. A transformer winding is missing a parent object (the substation). The substation identity comes from a guesswork based on the position of the nearest found busbar.

 

Test 28. (#_#28)

Series reactor data is missing

Mandatory data for calculation is missing. At least reactance must be given.

 

 

 

Analysis of meshes and connected stations
The function tries to identify the meshed network parts as well as interconnected stations that are connected in the underlying network.

Parallel network parts with or without joints are not to be considered as meshes.
If a mesh or connected stations are found, the result will only present the common section not the branches to facilitate the analysis. Se example.

 

Example 1

Meshed network with only one circuit.

 

If a mesh is found, a form  is displayed with information about the meshes and its network parts . Press the button Highlight enhanced and all the loops / meshes will be highlighted with the specified tracing color.

 

 

Example 2

Meshed network with meshes inside meshes.

 

First Highlight all meshes

 

As there is a mesh "inside" a larger mesh, a new simulation and analysis is done to removing one mesh at a time and the result can be visualized by select one row at time in the list box and highlight the network which simulates a removal of a network object.

For each row in the list box one internal mesh is removed until all meshes are identified.

 

 

 

Exampel 3.

Two substations are connected in the LV network.

Press the button Highlight enhanced to the connection route between the substations.