Active Regeneration is a commonly used method from vehicle manufacturers to avoid the DPF becoming overloaded with soot. By squirting fuel directly onto the DPF (either on the exhaust stroke of the engine or through a fuel injector in the exhaust system), it kick starts DPF regeneration by literally using the extra diesel as lighter fluid to ignore the trapped soot and burn it away. This system is automatically triggered when the ECU in the vehicle detects build up of soot in the DPF.
You may be thinking, in that case, that there is no need for a fuel component cleaning and DPF assist additive as the vehicle just sorts it all out itself. It seems pretty straightforward, but there are actually some negative impacts of this system.
If you often do slower speeds and more urban driving, then the DPF will have to actively regenerate more regularly which will result in more fuel consumption. You might notice a drop in miles per gallon as fuel is effectively being wasted every time the DPF is actively regenerated.
Another potential negative side-effect of this, is where a significant amount of fuel mixes into the engine oil when systems inject fuel on the exhaust stroke of the engine. This could lead to having to change the oil more frequently because the engine is negatively affected by the dilution of engine oil over time.