It explicitly shows that the grid current
is sinusoidal and in phase with the grid voltage, which implies that only real power is fed to the grid.
SAPF has been used extensively for harmonic suppression, reactive power compensation and grid current
equilibrium in the distribution system , .
where i(h),[i.sub.m](h) is the current harmonic of inverter side and the grid current
harmonic of switch frequency respectively.
However, many of them are based on THD of grid current
, , , which is impossible to calculate for predictive control with variable switching frequency or design is very simplified , .
11 shows the AC/DC Converter switching signals generation, where [V.sub.s,RMS] is the RMS Grid voltage value (V), and [i.sub.s,meas] is the measured Grid current
The research of the inverter shows that angle [[phi].sub.i1] is equal approximately to the phase angle of the modulation voltage of inverter [[phi].sub.m.] The grid current
for fundamental frequency is expressed as follows
The THD of the grid current
is over 10%, compared to only 2.30 % obtained in Case 1.
its advantages over the single H-bridge inverter are lower THDi of the grid current
and THDu of the output voltage, requirements of smaller filters, ability to transfer more power and smaller du/dt stresses.
Fig.11 shows the simulation results of load current, APF current and grid current
and voltage, corresponding to reactive power compensation mode, when the switch denoted by [sw.sub.2] is turned off (Fig.3).
In , a distribution static compensator was designed with neural fuzzy network to reduce the harmonics of grid current
and improve the voltage of DC-link.
[I.sub.a] is the output current of the qZS inverter, [I.sub.g] is grid current
; in which case it is Voltage Source Generator (VSG) current.
Figure 6 shows the harmonic components of the injected grid current
in correspondence to the number of charging cycles; frequency domain data are obtained performing a Fast Fourier Transform (FFT).