  Power-to-gas (P2G) can be employed to balance renewable generation because of
its feasibility to operate at fluctuating loading power. The fluctuating
operation of low-temperature P2G loads can be achieved by controlling the
electrolysis current alone. However, this method does not apply to
high-temperature P2G (HT-P2G) technology with auxiliary parameters such as
temperature and feed rates: Such parameters need simultaneous coordination with
current due to their great impact on conversion efficiency. To improve the
system performance of HT-P2G while tracking the dynamic power input, this paper
proposes a maximum production point tracking (MPPT) strategy and coordinates
the current, temperature and feed rates together. In addition, a comprehensive
dynamic model of an HT-P2G plant is established to test the performance of the
proposed MPPT strategy, which is absent in previous studies that focused on
steady states. The case study suggests that the MPPT operation responds to the
external load command rapidly even though the internal transition and
stabilization cost a few minutes. Moreover, the conversion efficiency and
available loading capacity are both improved, which is definitely beneficial in
the long run.
