Before a network analysis can be carried out, the distribution network has to comply to a number of conditions:
•the network must have a sound load flow
•the network must be well protected against all possible short-circuits
•all protections must be correctly set
•all nodes (and possibly cables and connections) must be provided with failure frequency data
The procedure simulates short circuits on all selected nodes, cables and connections. Their failure frequency determines the yearly occurrence rate. Following each short-circuit, the voltage dips in the whole network are calculated. The protection action determines the duration of each corresponding voltage dip.
Start the calculation using: Calculations | Voltage dip analysis.
The calculation may take some time, depending on the network size and the number of short-circuits in branches.
Options
The network analysis options (Application menu | Options | Calculation | Network analysis | Voltage dip analysis and protection analysis) define two options.
Number of cable calculation steps
The number of cable calculation steps determines how many short-circuits have to be simulated in all cables and connections. Default the number of calculation steps is zero. The maximum is 9. An option has been added to simulate short-circuits close to the from and to nodes (1% and 99% of distance).
Fault type share
The fault type share is a range of numbers, defining the weight of all possible fault types in the failure frequency parameter. Next example defines that a single phase to ground fault occurs twice as much as a two phase to ground fault and as a three phase fault. This means that e.g. for a cable failure frequency of 0.02 /km/year, the frequency of a single phase to ground fault is 0.01 /km/year and for the other two fault types 0.005 /km/year.
See also: