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Unbalanced Load Flow

Model a system with detailed representation of component unsymmetrical characteristics and accurate operating conditions.

For a robust and efficient power flow, the solution method must model distribution systems and their special features with sufficient accuracy. You can easily model your unbalanced system with ETAP’s Unbalanced Load Flow, providing detailed representation of the unsymmetrical characteristics of components. Your system’s unbalanced operating conditions are described accurately and reliably. ETAP’s Unbalanced Load Flow is the most advanced program available today with advanced features such as automatic line constant calculation and automatic alarm / warning.

Key Features

  • Unbalanced power flow
  • Modeling of unbalanced 3-phase and single-phase systems
  • Nonlinear and unbalanced modeling of loads
  • Power, current, phase and sequence voltage
  • Monitors unbalance factors for voltage and current
  • Coupling of transmission lines
  • Device are evaluated automatically

Unbalanced Load Flow Diagram:
Unbalanced Load Flow Diagram


  • 3-phase (3W &4W), 2-phase (2W & 3W), 1-phase
  • Unbalanced branches and loads
  • Specify internal sequence impedances of machines
  • User selectable grounding types for transformers and machines
  • Coupling between phases of multiple or single transmission lines
  • Loads modeled as constant power, constant current and constant impedance
  • Model generic loads
  • Isochronous or droop mode for generator governors
  • AVR or Mvar /PF control for generator exciters
  • Load tap changer capability for transformers (LTC /regulators)
  • Custom Phase-shifting for transformers

Flexible Operations

  • Various operating conditions
  • Up to ten loading categories – user customizable
  • Up to ten generation categories – user customizable
  • Numerous demand factors – user customizable
  • Infinite configurations
  • Varied nameplate data
  • Bus diversity factors can be defined globally or individually

Unique Features

  • Power sources can be: Swing, voltage regulated, and unregulated
  • Voltage regulator settings can be auto-adjusted
  • Infinite configurations
  • Various operating conditions
  • Numerous demand factors – user customizable
  • System of current-injection
  • The automated error checking system has five levels
  • The solution control conditions and parameters can be save for each scenario
  • System studies can be re-run instantly to see the effects of changes on your system
  • The single database with 10,000+ bus capability can perform unlimited “what if” studies

Automatic Result Evaluation

  • Warning and alert limits are user defined
  • Overloading: monitors bus, cable, line, transformer, and reactor overloading
  • Voltage: monitors bus over / under voltage conditions
  • Generator: monitors overload and over / under excitation
  • Unbalanced Level: monitors voltage and current unbalance
  • Negative and zero sequence: monitors voltage and current unbalance

Study Options

  • Convergence conditions are user controlled
  • Different loading conditions
  • Different generation levels
  • Fast convergence can be achieved through advanced solution methods
  • Conditions for temperature and tolerance can be automatically adjusted
  • Initial conditions can be updated


  • Individual power, current, and phase & sequence voltage
  • Voltage and current unbalance factors, power factor, power flow, voltage drops, losses, etc
  • Summaries, input data, and load flows
  • One-line graphical display of results
  • Reports can be exported in multiple formats
  • Device evaluation results are graphically displayed
  • Bus voltage alerts are graphically displayed
  • One-line diagrams can be exported to third party CAD systems including results
  • The alert view can be manually or automatically display critical and marginal alerts

» Download Unbalanced Load Flow Analysis Software PDF

ETAP Balkan, Nispetiye Mahallesi, Gazi Güçnar Sokak, Uygur İş Merkezi, No:4A, Beşiktaş, İstanbul 34340 TURKEY