What does the reactive power capability curve show?

The reactive power capability curve is a graphical representation that illustrates the limits of a system's ability to provide or consume reactive power at different levels of active power generation. This curve is essential in understanding how much reactive power can be supplied or absorbed by equipment, such as generators, transformers, or synchronous machines, under varying load conditions.

The reactive power is crucial for maintaining voltage levels within an electrical system and for ensuring the smooth operation of AC power systems. The curve typically shows upper and lower boundaries for reactive power output corresponding to specific levels of active power output. By analyzing this curve, engineers and operators can determine if a power plant or substation can support the required reactive power for a specific operational scenario, ensuring the stability and efficiency of the electrical grid.

Understanding this capability is vital in the planning and operation of power systems, especially in areas with fluctuating loads or where renewable energy sources are integrated.