Basically, you can use the ADE7754 to acquire all analog data, also waveform sampling for harmonics measurement up
to 26 kS/s. Measurement methods for harmonics are specified in power quality standards. For a final project, you should
know about these documents. If I remember right, they are suggesting FFT with overlapping windows, synchronized to the
fundamental. Using the ADE7754 as analog frontend involves, that you can measure harmonics for one input channel
at a time. I don't know, if this complies with your project specification.
You also need a processor with some RAM for raw data storage and FFT calculation, and sufficient speed to
acquire the analog data.