Novel Soft-Start Technique for Grid Integration of LCL-filtered Inverters

Abstract

Start-up inrush current is the major threat on the reliability of the power electronic converters which may occur due to even a micro-level mismatch in the grid synchronization of inverters. This paper presents a novel technique to limit the inrush current while simultaneously reducing the synchronizing time. A feedforward voltage loop is introduced along with a current control loop with varying weightage (gain factors). In addition, the current control loop gain is adjusted at the start-up so that it catches up faster to further reduce the inrush current. A detailed investigation of the causes of the inrush current and the effect of the control loop dynamics is carried out. The effectiveness of the proposed technique is compared with various other start-up techniques in the literature. The results are validated through simulation and experimentation.

KEYWORDS:

• Grid-connected inverter
• Soft-start
• LCL filter
• Feedforward control

Additional information

Notes on contributors

R. Parthiban

R Parthiban received his BTech degree in electrical and electronics engineering in 2012 and MTech degree in electrical drives and control in 2014, both from Pondicherry Engineering College. He is currently pursuing PhD degree in the field of electrical engineering, Anna University, Chennai. His areas of interests include design, control and implementation of power converters and grid-connected inverters. Corresponding author. Email: [email protected]

B. Umamaheswari

B Umamaheswari received the BE, ME, and PhD degrees from Anna University, Chennai, India, in 1985, 1988, and 1994, respectively. She is presently a professor at Department of Electrical Engineering, Anna University Chennai, India. She has been the task team member for power for ANUSAT, a first Indian university built micro-satellite. She has expertise in the areas of special electrical machines, power electronics and control systems both in design and implementation. She has many publications in leading journals and held various administrative positions. Dr Umamaheswari was awarded with common wealth fellowship (1995–1996) in Robotics. Email: [email protected]