Calculations

In Vision a number of calculations can be performed. The calculations influence the network on all sheets, not just the active sheet. See:

•Load flow: regular load flow for calculating voltages and currents in any operating situation

•IEC 60909: calculation of short-circuit currents according to the international standard IEC 60909

•Fault analysis: analysis of specific fault situations

•Network load: calculation of load flows with different load/generation settings

•Harmonics: analysis of the behaviour of the currents and voltages at higher frequencies

•Costs: determining the cost of losses and for comparing the cost of different variants

•Reliability: calculation of reliability characteristics of a network

•Protection: analysis of the behaviour of the protection in case of a short circuit

•Voltage dip analysis: function for the analysis of the effects of short circuits on the voltage

•Failure analysis: function for the analysis of faults

•Normal open point optimization: calculation of the optimal location of the normally open points in a distribution network

•Data driven loadfow: load flow based on measurements

•Outage simulation: interactive resolution of a short circuit (available upon request)

•Dynamic analysis: insight into the dynamic behaviour of the currents, voltages and other variables

•Stability analysis: calculate system eigenvalues to determine whether a system is stable in case of deviations (small-signal stability analysis)

•IEC 61363: calculation of short circuit currents for ships

•Arc flash: calculates the arc flash energy

•Remaining capacity: calculation of power still to be connected

•Netcheck: calculating the network load for a new load

•Power generating module: calculate a wind or solar farm

•Switchability: analyzes the restoration of electricity supply during grid failures

•Frequency disconnection: calculating network parts to be switched off when frequency decreases.

Time

The time (year number) can be specified to set the time-dependent loads according to their eventually specified yearly growth. By choosing a year, in the ribbon menu Start | Time, the loads in the network are set to a value corresponding to the growth. All calculations are now performed with these new load values.

The year setting does not function when a variant and/or a scenario is active.

Variant

A variant describes modifications to a network model that will occur on certain specified dates (in the future). Using variants, all stages of the commissioning and decommissioning of network components can be evaluated.

A variant can be activated by using Variants | Set | Variant. The variant can be chosen from a list of existing variants. A variant can be deactivated by choosing: None.

The actions can be activated by specifying the Date. All events until that date will be in effect. In the standard view all objects will be visible according to the variant-list. Before means that the variant is active, but the time has been set before the first date of any event in the variant-list.

Scenario

A scenario describes the settings and changes to objects parameters in the whole network. The changes can be independent of time but also a chronological table of events can be defined. The parameters which can be changed are: switch state, transformer tap setting, real power, reactive power and apparent power.

The network can be set to one scenario on a specific date in the scenario chronological table of events, using Variants | Set.

Parameter changes without a specific date, will be effective any time the scenario has been activated, not dependent on the chosen date.

A scenario can be deactivated by choosing: None.