Control of Power Flow

There are several methods to control power flow in power systems:

1. Prime mover and excitation control of generators
2. Switching of shunt capacitor banks, shunt reactors, and static var systems
3. Control of tap-changing and regulating transformers

A simple generator in the system is represented by its Thevenin equivalent circuit, which represents its model operating under balanced steady-state conditions. The key parameters include the generator terminal voltage V_t, the excitation voltage E_g, the power angle δ, and the positive-sequence synchronous reactance X_g.

The generator current is:

and the complex power delivered is:

A shunt capacitor bank added to a power system bus increases the bus voltage magnitude and compensates for reactive power. This adjustment is modeled by connecting a capacitor, which absorbs negative reactive power, thereby reducing the overall reactive power demand from the system. Additionally, tap-changing transformers are used to regulate bus voltages and manage reactive power flows by adjusting the turns ratio, thereby influencing the voltage and reactive power profile in the network. This adjustment helps maintain system stability and efficiency, accommodating load variations and enhancing power delivery.

Power flow studies often use trial and error to adjust generation levels and control settings. These adjustments ensure the system meets desired equipment loadings and voltage profiles, preparing the network for load growth, new transmissions, transformers, and generation. The control of power flow is a dynamic process involving various methods and adjustments to maintain system stability, efficiency, and reliability.