Multi-Domain Dynamic Simulation and Round-Trip Efficiency Verification of a 90 kW Solar Photovoltaic Adiabatic – Compressed Air Energy Storage (A–CAES) System Using MATLAB/Simscape

Adequate electricity is critical enabler for agricultural productivity in Zimbabwe and the Chinhoyi University of Technology (CUT) Farm, which has an aggregate demand of 115.63 kW, is frequently subjected to load shedding due to a structural generation gap of about 700 MW. Solar PV generation has an excellent resource base of 5.5 to 6.5 kWh/m2/day but has the constraint of not being able to deliver firm and dispatchable generation without a storage system to absorb day time excess and return it as firm and dispatchable generation during the night. In this paper, a multi-domain dynamic model of a 90 kW Solar PV Adiabatic Compressed Air Energy Storage (PV-A-CAES) hybrid system sized with the CUT Farm load profile is developed and verified using the developed dynamic model before the exergy and techno-economic analysis is carried out. The model includes a PV array and incremental-conductance MPPT boost converter, two-loop Field-Oriented Control (FOC) of the machine-side and grid-side boost converter, two-stage intercooled compression and charging train, and a thermal energy storage (TES) that recovers the heat of compression and feeds it back into a radial inflow turbine during discharge. The transient simulation demonstrates that that discharge delivers a steady 90 kW at the design pressure ratio (β = 69.1), and that the discharge-side current and torque responses are well damped. The coordinated gains in compressor, turbine and TES performance increase the simulated RTE from a diabatic operating point at 49.0% to a validated operating point at 132.7 kW and 90 kW, which is checked here against the compressor and turbine performance of the Huntorf plant, as well as against the performance of the McIntosh plant, and carried forward explicitly to the exergy and Levelized-cost analyses that follow this study.