2-Bus Loadflow

This example shows a model of a two-bus three-phase power system network. The model uses three instances of the Load Flow Source block from Simscape™ Electrical™, one configured to be the swing bus, one configured to be the PV bus, and one configured to be the PQ load. The PV bus regulates its output to be at a voltage of 1.025 times rated voltage and to deliver 80MW active power to the network. The Swing bus regulates voltage at the other end of the transmission line to be one times rated voltage, and it delivers the requisite power to the network so that overall active and reactive powers balance. The Simscape initialization solver determines the required internal initial voltage amplitudes and phases in both the PV bus and the Swing bus so as to start in steady state.

The two busbar blocks are tagged with a summary of the load flow initialization results. These tags are updated immediately following simulation of the model. From the first row of the tags it can be seen that the requested voltages at the terminals of the two sources have been honored. The second rows of the tags show that Busbar2 leads Busbar1 by 2.51 degrees, this reflecting that there is a net power flow from Busbar2 to Busbar1. The third and fourth rows show the active and reactive powers respectively. For example, the third row of the Busbar2 tag indicates that 60MW of active power flows out of the busbar to the transmission line, 80MW of active power is supplied by the PV bus, and that 20MW of active power is delivered to the PQ load.

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Simulation Results from Simscape Logging

The plot below shows the simulation results following the steady state initialization to meet load flow targets. The Equation formulation option on the Solver Configuration block is set to Frequency and time for fast simulation. This model can also be run using the Time option provided that the Start simulation from steady state option is checked on the Solver Configuration block. However, simulating using the Time option does not update the Busbar blocks with loadflow results.