Synchronization is a crucial problem in the grid-connected inverter’s control and operation.
A phase-locked loop (PLL) is a typical grid synchronization strategy, which ought to have a high
resistance to power system uncertainties since its sensitivity influences the generated reference signal.
The traditional PLL catches the phase and frequency of the input signal via the feedback loop filter
(LF). In general, to enhance the steady-state capability during distorted grid conditions generally,
a filter tuned for nominal frequency is used. This PLL corrects large frequency deviations around
the nominal frequency, which increases the PLL’s locking time. Therefore, this paper presents an
adaptive feed-forward PLL, where the input signal frequency and phase under large frequency
deviations are tracked precisely, which overcomes the above-mentioned limitations. The proposed
adaptive PLL consists of a feedback loop that reduces the phase error. The feed-forward loop
predicts the frequency and phase error, and the frequency adaptive FIR filter reduces the ripples in
output, which is due to input distortions. The adaptive mechanism adjusts the gain of the filter in
accordance with the supply frequency. This reduces the phase and frequency error and also decreases
the locking time under wide frequency deviations. To verify the effectiveness of the proposed
adaptive feed-forward PLL, the system was tested under different grid abnormal conditions. Further,
the stability analysis has been carried out via a developed prototype test platform in the laboratory.
To bring the proposed simulations into real-time implementations and for control strategies, an Altera
Cyclone II field-programmable gate array (FPGA) board has been used. The obtained results of the
proposed PLL via simulations and hardware are compared with conventional techniques, and it
indicates the superiority of the proposed method. The proposed PLL effectively able to tackle the
different grid uncertainties, which can be observed from the results presented in the result section.