Ipsa 2 Load Flow

Features

  • All voltage levels from 415V to 400kV
  • Radial, meshed and islanded networks
  • Model AC and DC systems in the same network

Benefits

  • Fast and accurate results
  • Check voltage levels and power flows
  • Profile analysis for time of day studies
  • Contingency studies up to N-3 outages

Ipsa is routinely used to perform load flow studies on networks ranging from large, fully-meshed distribution and transmission networks through to small islanded systems, such as off-shore platforms, industrial facilities and wind farms.

Analysis Method

Load flow calculations are performed using fast-decoupled Newton-Raphson load flow technique that robustly handles both radial and meshed networks at all voltage levels.

Multiple network areas and complex DC systems can also be modelled.  Slack busbars are automatically identified for each network area.

Feeder load  flow analysis allows the calculation of voltage drops along distribution feeders under varying loading conditions.

Contingency analysis allows rapid analysis of larger networks to identify critical circuits and the resulting overloads and voltage violations. Studies may be performed up to a depth of N-3 across the full network or a user specified selection. Automation analysis extends the capabilities even further by allowing the user to specify individual switching actions, including restoration.

Network Components

Synchronous Generators

PV, PQ and slack generator controls are provided, together with voltage control bandwidth.  Reactive power limits can be added.

Utility Grid Infeed

A grid infeed model can be used to represent external networks based on peak and RMS LLL and LG fault contributions.

Induction Motors

Represented using single or double cage parameters with load torque-speed characteristics.  Doubly-fed machines for wind turbine modelling are provided.

Transformers

Tap-changers with tap limits, relay bandwidth and compound voltage control.  Vector groups can be specified as well as auto-transformers and phase-shifting transformers.

Loads

Static load model represents constant power loads.  These can be grouped and scaled with load transfers due to switching represented

Circuits and Branches

Unlimited rating sets can be added for overload checks.  Zero impedance and zero sequence branches both allowed.  Multi-section branches can be modelled to represent different cable or line types on the same circuit.

Circuit breakers with intertripping schemes and protection devices can be attached at either end of a branch.

Universal Machines

A generic constant power load or generator model that can be extended using a user defined dynamic model.

Harmonic Filters

The most widely used filter types are included, such as single-tuned, double-tuned and C type.

Mechanically-switched Capacitors

Voltage or power factor control methods can be represented.

Enhanced Modelling with Plugins

Load flow plugins provide the ability to represent more complex voltage dependant devices in the load flow calculation, such as generators with voltage droop, or SCADA systems controlling many distributed components such as wind turbines.

Load Flow Features

The fast decoupled load flow engine handles multiple network areas, radial and meshed systems all with rapid convergence.

Options include the ability to lock transformer taps, apply load scaling and flat starts, identify and implement protection relay operation. Convergence and iteration limits are also adjustable.

Results are displayed in tables, reports and on the diagrams.  Selection of the results format is configured by the user.  Components can be coloured by nominal voltage, per-unit voltage, status and power flow.  Limit checking can be applied and animated power flow symbols indicate flow directions and relative magnitudes.

 

Feeder Load Flows

Feeder load flows are particularly useful for investigating voltage regulation and power flows on large distribution networks. Load flow studies can be undertaken on single feeders or substations within a larger network. The voltage drop along the feeder can be displayed graphically allowing the network operator to quickly identify system constraints.