A Review of Control Techniques and Energy Storage for Inverter-Based Dynamic Voltage Restorer in Grid-Integrated Renewable Sources

Table 9

Potentials and constraints of various DVR topologies.

Location of filter	Inverter side	Higher-order current harmonics are eliminated before entering the injected transformer. The fundamental component consists of voltage drop and phase shift. Influence the control system in the DVR.
	Line side	The control system in the DVR is not affected.
		Less efficient than inverter side connected filter.
Injection transformer (IT)	Without IT	Minimizing the size, weight, and cost.
		Saturation and inrush current issues are not present.
		Not recommended for high voltage applications.
	With IT	The voltage rating of the inverter is proportional to the turn ratio of the transformer.
		Preferable for high voltage applications.
		Downstream fault current protection of the transformer is difficult.
		Saturation and inrush current issues are present in the transformer.
		Requires high-frequency transformer.
		Efficiency is relatively poor.
Energy storage (ES)	Without ES	Cost-effective.
		Small and modular design.
		Suited for strong electrical grids.
		The burden on the grid is more and hard to control.
	With ES	Better performance.
		Less burden on the grid.
		Easy to control.
		High cost.
		When the energy stored is lost, the capability of compensation reduced.