Reactive power compensation related terms

1.Basic principle of reactive power compensation
The basic principle involves connecting a device with capacitive power load in parallel with an inductive power load in the same circuit. When the capacitive load releases energy, the inductive load absorbs it; conversely, when the inductive load releases energy, the capacitive load absorbs it. This exchange of energy between the two types of loads allows the reactive power absorbed by the inductive load to be compensated by the reactive power output by the capacitive load. This is the fundamental principle of reactive power compensation.
2. Power factor penalty
This refers to the additional charge imposed on electricity users as a percentage of their electricity bill when the reactive power consumption of their inductive loads is excessively high, causing the power factor to fall below national standards.
3. Inrush current and overvoltage
Inrush current is the instantaneous current generated when a capacitor is switched on. For example, when a contactor switches on a capacitor without crossing the zero-voltage point, the capacitor behaves like a short circuit at the moment of switching, resulting in a current that can be tens or hundreds of times greater than the capacitor's rated current. This can puncture many weak points in the capacitor's dielectric layer, rendering the capacitor unable to store energy and shortening its service life. Therefore, contactor-based capacitor banks should not be switched frequently.
Overvoltage is the instantaneous voltage generated when a capacitor is switched off. When the capacitor is disconnected, the grid voltage and the capacitor's terminal voltage superimpose, leading to overvoltage.
4. Switching oscillation
Switching oscillation occurs when switching on a capacitor results in overcompensation, while switching it off leads to undercompensation, causing the capacitor to switch on and off frequently and creating oscillations.
5. Overcompensation and undercompensation
Undercompensation refers to a situation in the power consumption system where inductive reactive power exceeds capacitive reactive power.
Overcompensation refers to a situation in the power consumption system where capacitive reactive power exceeds inductive reactive power.
6. Harm of reverse reactive power transmission
Reverse reactive power transmission, like undercompensation, causes a phase difference between voltage and current, resulting in an excessively low power factor.