Reactive power of capacitors

From Electrical Installation Guide

The current flowing through capacitors is leading the voltage by 90°. The corresponding current vector is then in opposition to the current vector of inductive loads. This why capacitors are commonly used in the electrical systems, in order to compensate the reactive power absorbed by inductive loads such as motors.

Inductive-reactive power is conventionally positive (absorbed by an inductive load), while capacitive-reactive power is negative (supplied by a capacitive load).

As reactive-inductive loads and line reactance are responsible for voltage drops, reactive-capacitive currents have the reverse effect on voltage levels and produce voltage-rises in power systems.