Parameter Design of a Novel Series-Parallel-Resonant <italic>LCL</italic> Filter for Single-Phase Half-Bridge Active Power Filters

Voltage Harmonic Suppression by Means of Grid-Connected Converters Using only Local Measurements

“…Both v g (s) and i ld1 (s) are regarded as external disturbances to the model, and v * inv (s) plays the role of the control action. Here p 1 (s) to p 6 (s) are the plant open-loop transfer functions (refer to (5) for the relation between input and output), which can be derived straightforwardly following a conventional modelling procedure of the grid-connected converter with LCL filter [23], hence their expressions are omitted in this paper.…”

“…Analyzing the plant model in (5) and the controller model in (6), the resultant converter output current and the pcc voltage in the closed-loop system can be expressed as…”

“…Voltage harmonic compensation is mostly fulfilled by placing a converter in series with the distorting voltage source, where the converter generates a voltage to compensate for the voltage harmonics [4]. Current harmonic compensation is achieved by placing a converter in parallel with the harmonic current source, where the converter serves as a current source to compensate for the current harmonics [5]. The focus of this paper is on the harmonic compensation strategy applied in these shunt grid-connected converters.…”

“…The first category is focused on improving its immunity to harmonic disturbances coming from the grid and load and overcoming the non-linearities of the converter itself in order to inject sinusoidal current into the grid [6][7][8]. The second category is devoted to absorbing harmonics caused by polluting loads by acting as an active power filter (APF) [5]. The last category intends to sink harmonics introduced by local loads in addition to (bidirectionally) exchanging active power with the grid [9][10][11][12][13][14][15][16].…”

Resonance Frequency Detection Technique in Gridconnected Inverter Systems Based on Double-order Digitalized Filter

“…Consequently, the fixed resonance frequency assumed in the design process of the LCL filter is no longer fixed anymore but changes whenever the equivalent grid impedance changes. In addition to instability problems, the existence of the resonance frequency can weaken the power quality and damage protection devices [6]. Therefore, appropriate damping techniques must be added to the system in order to suppress or even prevent the resonance effects of the LCL filter.…”