Title :
Decentralized Parallel Operation of Inverters Sharing Unbalanced and Nonlinear Loads
Author :
De, Dipankar ; Ramanarayanan, Venkataramanan
Author_Institution :
Dept. of Electr. Eng., Indian Inst. of Sci., Bangalore, India
Abstract :
In this paper, a wireless control strategy for parallel operation of three-phase four-wire inverters is proposed. A generalized situation is considered where the inverters are of unequal power ratings and the loads are nonlinear and unbalanced in nature. The proposed control algorithm exploits the potential of sinusoidal domain proportional+multiresonant controller (in the inner voltage regulation loop) to make the system suitable for nonlinear and unbalanced loads with a simple and generalized structure of virtual output-impedance loop. The decentralized operation is achieved by using three-phase P/Q droop characteristics. The overall control algorithm helps to limit the harmonic contents and the degree of unbalance in the output-voltage waveform and to achieve excellent power-sharing accuracy in spite of mismatch in the inverter output impedances. Moreover, a synchronized turn on with consequent change over to the droop mode is applied for the new incoming unit in order to limit the circulating current completely. The simulation and experimental results from -1 kVA and -0.5 kVA paralleled units validate the effectiveness of the scheme.
Keywords :
decentralised control; distributed power generation; invertors; proportional control; voltage control; decentralized parallel operation; distributed generation; inner voltage regulation loop; microgrid; nonlinear loads; output-impedance loop; proportional+multiresonant controller; three-phase PIQ droop; three-phase four-wire inverters; unbalanced loads; wireless control strategy; Converters; Impedance; Inverters; Phase locked loops; Reactive power; Voltage control; Wire; Microgrid; output impedance; proportional+ multiresonant controller; start-up phase-locked loop (PLL); wireless control;
Journal_Title :
Power Electronics, IEEE Transactions on
DOI :
10.1109/TPEL.2010.2068313