A New Design Method of LCL Filter for Single Phase Grid Connected Power Converter

LCL filter design for grid-connected single-phase flyback microinverter: a step by step guide

“…where V o is the rated output voltage, P o is the rated power in total, and ω o is a grid angular frequency. While, α is the power ratio and αP o is a quantity of reactive power absorbed by the filter which is typically less than 5% [5], [11], [18]. Equation ( 5), it can be seen that the reactive power absorption is directly proportional to the capacitance value, which means that the higher the capacitance, the more power is absorbed by the capacitor.…”

“…The relationship between the resonance frequency and the inductance ratio r is illustrated in Figure 4. The resonance frequency of the LCL filter must comply with the following constraint where it should be in the range between ten times of grid frequency and half of the switching frequency [1], [3], [5], [6], [11], [27], [28]. Figure 5: The impact of a dampening resistor, R d, on the stability of a system…”

“…These variations cause resonance frequency shifting and subsequently resulting in instability to the control system and the filter behavior. A great number of works have been carried out to deal with the resonance and instability such as the passive damping approach [5]- [7], active damping method [8]- [10], and even dampingless method [4], [11] to achieve the stability criterion based on various types of control techniques. Nonetheless, there is very limited literature that elaborates a clear step-by-step guide to choose appropriate passive element values for the filter, especially of the open-loop type.…”