INTERACTIVE POWER FACTOR COMPENSATION CHART & EXPECTED POWER FACTOR CONTROLLER PERFORMANCE

The following webpage provides expected performance of power factor controllers that utilize proportional control algorithms for the control of single and multi-stage capacitor banks and harmonic filter banks. Required information includes: real power level of loads, the capacitor/filter bank stage rating in kvar, target power factor, and the dead band setting in percent within the controller.

Various parameters are calculated to provide a full understanding of expected controller performance. Uneven inductive and capacitive dead band values can be examined to determine effect on controller performance.

Note:

1. Three-Phase Real Power of load to be compensated in KW.
2. Power Factor of Load to be compensated.
3. Target Power Factor of Load to be compensated. The target power factor is drawn as a linear line on the PQ diagram (see below).
4. Three-Phase capacitor bank reactive power rating in kvar (the smallest step size in a multi-stage capacitor bank using binary step sizes).
5. Inductive dead band width – the inductive level or "neutral zone" where no switching action occurs (the controller will not switch in this zone). The dead band prevents oscillation or repeated activation-deactivation cycles (called "hunting" in proportional control systems). The width of the inductive dead band is defined as a percentage of the capacitor step size.
6. Capacitive dead band width – the capacitive level or "neutral zone" where no switching action occurs (the controller will not switch in this zone).
7. Dead band width - equal to the sum of the capacitive and inductive dead band values. Usually a value near 150% is recommended.
8. Reactive power level before compensation.
9. Inductive switching level - required reactive power level required for a capacitor stage to be switched on (green line in graph below).
10. Target reactive power level (black line in graph below) based on present power factor and real power level.
11. Capacitive switching level - required reactive power level required for a capacitor stage to be switched off (red line in graph below).
12. Expected controller action based on data provided.
13. Reactive power required to meet target power factor – Difference between the present reactive power level and the target reactive power level. A negative value indicates leading vars.
14. Total power of load before power factor correction.
15. Total power of load at target power factor.
16. Total power reduction as a result of applying power factor correction.
17. Power factor at inductive switching level based on present real power level.
18. Power factor at capacitive switching level based on present real power level.
19. Line-to-line system voltage. Value is used to calculate C/K ratio (commonly referred to as response value) for power factor controller setup.
20. CT (current transformer) ratio used to calculate C/K ratio for power factor controller setup.
21. Inductive response value (C/K ratio) defines the inductive switching level in current transformer secondary amps based on the capacitor stage size, CT ratio, dead band width, and system voltage.
22. Capacitive response value (C/K ratio) defines the capacitive switching level in current transformer secondary amps based on the capacitor stage size, CT ratio, dead band width, and system voltage.