Linked from
The 12 pages that link to Reactive power, each with the reason it gives.
Electric power transmissionRelated: Its control helps maintain voltage across transmission networks.
Power inverterRelated: Inverters can regulate reactive power and thereby influence grid voltage.
Power system stabilityRelated: Its availability strongly affects voltage stability.
Ancillary servicesBroader topic: Voltage support depends on controlling this component of AC power.
Power-flow studyRelated: Its injections strongly influence bus-voltage magnitudes in the solution.