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

Table 11

Comparison of various linear controllers.

Parameter	Feedback	Feedforward
Stability	Can be unstable	Good
Response time	Medium and controllable	Fast and depends on the system
Measures	Load side voltage	Grid side voltage
Transient overshoot	Controllable	Not easy to control
Steady-state error	Can be eliminated	High
Switching harmonics	Penetrate the control	Do not penetrate the control
Compensation of asymmetrical fault	Good	Possible but slow
Compensation of DVR generated voltage	Can be reduced	Difficult to control

Composite controller measures the load side voltage for feedback and grid voltage for feedforward, and the response time of it has a strength of both feedforward and feedback.