Use these examples to learn how to model power system networks and perform
loadflow and harmonic analysis.
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.
A three-phase cable model comprised of multiple pi-sections. Each phase is enclosed in a conductive sheath. The conductive sheath is connected to ground at either end of the cable through a simple resistance. A high-voltage source provides power to an unbalanced resistive load through the power cable. You can configure the sheath to be either series-bonded or cross-bonded. You can also configure the number of pi-sections. Increasing the number of pi-sections improves the accuracy but slows down the simulation. To facilitate convergence, the voltage source includes an internal impedance.
The effects of three different types of earthing connections on network voltages and currents.
A model of a 9-bus three-phase power system network. This example is based on an IEEE benchmark test case, further details of which can be found in "Power System Control and Stability" by P. M. Anderson and A. A. Fouad (IEEE Press, 2003). Simscape™ initializes two of the generators to the specified powers and terminal voltages, and initializes the remaining swing bus generator to meet just the specified voltage. The resulting load flow solution is appended to each of the busbars post-simulation. The four rows correspond to per-unit voltage, phase, active power, and reactive power respectively. Looking at Bus 1, it can be seen from the annotation that the swing generator delivers 76.4MW of active power and 27.5MVAr or reactive power to the network. Differences to the original benchmark are due to the transmission line models and transformer configurations used.
Initialize a three-phase induction motor as part of a load flow analysis. When initializing an induction machine that is directly connected to an AC network, in steady state there is one degree of freedom which can be set by any one of shaft torque, shaft power, motor speed or electrical power.
Configure your model to use frequency-time equation formulation.
Initialize synchronous machine as part of a load flow analysis. When initializing a synchronous machine there are two degrees of freedom which can be set by any two of rotor angle, active power, reactive power and terminal voltage. The pair of variables that are constrained is set by the source type drop-down menu, this having options of Swing bus, PV bus and PQ bus. Here the machine is configured for a swing bus with a 1.02 per-unit voltage and zero degrees phase.
Model a four-section ladder network that comprises RLC components with mutual coupling between multiple coils. You can use this ladder network representation to model the disc winding of a transformer. The number of sections of a ladder network depends on the number of discs in the winding. Each section can model two or three discs in the winding.
Model a distance relay in an AC microgrid. The relay block comprises impedance relay characteristic and mho relay characteristic. You can use this example to study the performance of impedance relay and mho relay in various fault conditions. Both the relays have two types of relays for ground fault and phase-phase fault.
Model an overcurrent relay in an AC microgrid. You can use this example to study overcurrent relay coordination in a microgrid. The Relay block comprises two protection units, phase protection and earth protection. The phase protection unit protects the microgrid from high phase currents. The earth protection unit protects the microgrid from high earth currents. In this example the relay2 block protects the distribution_line2 block. The relay1 block protects the distribution_line1 block and also acts a back-up for the relay2 block. If a fault occurs on the distribution_line2 block and the relay2 block doesn't operate, the relay1 block operates after a specified time and isolates the system.To avoid tripping of the system, the relay1 and relay2 blocks operate such that only one relay operates at any given time. You can specify either time multiplier setting or the desired operating time of relay2 block.
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