PV Bus

A PV bus (also called a generator bus or voltage-controlled bus) is a bus type in power flow analysis where active power injection (P) and voltage magnitude (V) are specified as known quantities, while reactive power output and voltage angle are calculated by the solution.

Key Aspects of a PV Bus:

• Voltage Regulation: The voltage at a PV bus is maintained at a specified setpoint by automatically adjusting reactive power output through the generator's excitation system, increasing excitation to raise voltage, decreasing it to lower voltage.
• Prevalence: PV buses represent roughly 15% of all buses in a typical power system, corresponding to locations with active voltage control equipment.
• Reactive Power Limits: Every generator has finite reactive capability. If reactive power output reaches its upper (over-excited) or lower (under-excited) limit during the power flow solution, the bus converts to a PQ bus with reactive power fixed at that limit and voltage released from its setpoint.
• PV-to-PQ Switching: This switching behavior is an important aspect of power flow convergence and reflects the physical reality that generators cannot provide unlimited reactive support.
• Beyond Generators: Besides synchronous generators, other voltage control devices such as STATCOMs, SVCs, synchronous condensers, and tap-changing transformers can also create PV bus behavior in the network model.