Network concepts and calculations

Higher power densities, competition within the energy industry and the increase of distributed generation in connection with the shift to renewables call for constant network optimisation and expansion. We carry out detailed measurements of your primary and secondary technology and create the network models for our powerful simulation tools. On the basis of load flow and short-circuit calculations, we develop technically and economically optimised concepts for network expansion and protection technology.

Data acquisition and modelling of networks

Creation of network models for the calculation of medium or low-voltage networks with suitable network calculation tools:

1. Re-acquisition of the network data, if required
2. Data entry, configuration and verification of the network using the data provided by the customer
3. Documentation of the implemented network model as a block diagram in PDF format
4. Provision of the adopted or processed network data in Excel spreadsheets

Network calculation (load flow and short-circuit current)

Performance of network calculations on the basis of a network model which has been created. The calculations are made for the operating states defined by the customer or for the normal switching status. The following calculations are normally made / the following parameters are normally determined:

1. Load flow calculation with substitute loads on the low-voltage side
2. Compliance with selective error disconnection / selectivity analysis
3. Examination of cable capacity utilisation
4. Short-circuit current calculation (3-pole short-circuit) for the max. short-circuit current
5. Short-circuit current calculation (1-pole earth fault) for the min. short-circuit current
6. Determination of critical equipment
7. Verification of selectivity

The results of network, load flow and short-circuit calculations and individual parameters, such as selected protection parameters and parameter-time diagrams, are presented in a report.

Model extension or the editing of existing network models

Entry or editing of individual pieces of equipment (network elements), such as cables, circuit breakers, transformers etc in an existing network model.

Creation of network and protection concepts

Development of long-term network concepts (target network) on the basis of the structure and operational concept of the current network in close cooperation with the customer while taking possible future modifications into consideration. Formulation of suitable selective protection concepts including protection settings for the target network or for the individual migration steps. The concepts are described in a report and graphical representation is provided in the form of network plans.

Protection coordination

Assessment of protection concepts for the current and the target network:

1. Verification of the selectivity of the protection devices between the points of common coupling (PCC) and the first protection device on the low-voltage side of the transformers. Selectivity is verified from the PCC through to the largest circuit breaker feeder/l.v. h.b.c. fuse feeder of the first low-voltage bus bar on the secondary side
2. Preparation of suggestions for the setting parameters of network protection
3. Preparation of Z/t diagrams for the relevant protection branches with details of the fault current ranges, the pick-up currents, the tripping times and the relay characteristics
4. Verification of the selectivity of the protection devices installed in series
5. Creation of a report with a summary of the results of all previous reports