Title :
Admittance Compensation in Current Loop Control for a Grid-Tie LCL Fuel Cell Inverter
Author :
Chen, Chien-Liang ; Park, Sung-Yeul ; Lai, Jih-Sheng ; Moon, SeungRyul
Author_Institution :
Virginia Polytech. Inst. & State Univ., Blacksburg
Abstract :
Current loop transfer function of a single-phase grid-tie inverter has been systematically derived with representations of conventional transfer function format using admittance terms for controller design and loop compensation. The power circuit adopts the LCL type filter to allow universal output that can be operated in both standalone and grid-tie modes. The proposed admittance compensation along with a quasi-proportional-resonant compensator is designed to achieve high gain at the fundamental frequency while maintaining enough stability margin. The proposed current loop controller and admittance compensation have been simulated and tested with a 5-kW fuel cell prototype. Without the admittance path compensation, simulation results indicate that the system cannot start up smoothly and the zero current command cannot be tracked very well. At first simulation cycle, the power flow erratically fed back to the inverter that may cause catastrophe failure. With admittance path compensation, the time-domain current steady-state error can be easily reduced with the loop gain design in frequency-domain. Simulation and experimental results show that the inverter is capable of both standalone and grid-tie connection mode operations and smooth power flow control even with zero current command.
Keywords :
electric current control; fuel cells; invertors; load flow control; power capacitors; power filters; power grids; power inductors; transfer functions; admittance compensation; current loop control; current loop transfer function; grid-tie LCL fuel cell; inductor-capacitor-inductor type filter; power 5 kW; power flow control; quasiproportional-resonant compensator; single-phase grid-tie inverter; time-domain current steady-state error; Admittance; Circuit stability; Control systems; Filters; Frequency; Fuel cells; Inverters; Testing; Transfer functions; Virtual prototyping;
Conference_Titel :
Power Electronics Specialists Conference, 2007. PESC 2007. IEEE
Conference_Location :
Orlando, FL
Print_ISBN :
978-1-4244-0654-8
Electronic_ISBN :
0275-9306
DOI :
10.1109/PESC.2007.4342041