Stability Analysis and Robust Design of <italic>LCL</italic> With Multituned Traps Filter for Grid-Connected Converters

Abstract

Utilizing high order passive filters for the voltage source converters is becoming attractive in industrial applications due to the excellent attenuation performance, smaller size and lower cost. The LCL, the multituned traps and recently the combined LCL with multituned traps (LCL-mT) are the most popular high order filters. However, the increased number of elements and the inherent resonances complicate both filter parameter design and current control loop stabilization, especially, in presence of parameter uncertainties and wide variations of the grid inductance. Hence, in this paper a straightforward and robust design procedure for the LCL-mT filter is proposed. Compared to the existing methods, the proposed technique is not iterative and satisfies the traditional practical limits on filter parameters, while ensures stability even in presence of wide grid inductance variations and filter parameter uncertainties. The validity and effectiveness of the proposed method is proved by simulation and experimental results. Index Terms-Delay based stabilization, LCL and traps filters, single loop control, voltage source converter.

Control of Grid-Tied Converters for Integration of Renewable Energy Sources into the Weak Grids

“…In weak grid applications where the grid frequency is allowed to vary around 1%, an appropriate KI value can be found by frequency analysis [12], [13]. Moreover, utilizing high-order passive filters for the voltagesource converters has been widely used due to the excellent attenuation performance, smaller size, and lower cost [12], [13]. LCL filter is one of the most popular high-order filters and this type of filter is used in the implemented power converter.…”

LCL-resonance damping strategies for grid-connected inverters with LCL filters: a comprehensive review

“…Besides delay, in practical application the filter parameters may vary from their design values and the grid at the PCC has non-negligible impedance. The studies in [6,[27][28][29][30][31][32], and [64][65][66][67][68] showed that the resonance frequency is significantly reduced when the filter parameters and the grid impedance are varied.…”

“…However, the pulse width modulation (PWM) of the inverter produces many switching harmonics in the grid current. Thus, to limit these current harmonics according to standards such as IEEE Std 929-2000, an L or LCL filter is needed [4][5][6]. Compared with the L filter, the LCL filter with or without a harmonic trap in [5,6] can provide much higher attenuation of switching harmonics with reduced volume and weight so that the power density is increased.…”

Design of LCL ‐filter considering the control impact for grid‐connected inverter with one current feedback only

“…Moreover, f 3 and PM 3 are calculated and checked according to (14) and (15). For the integrator of PI or the resonator of PR, the design in [1,27] can be followed.…”