Real-Time Hardware-in-the-Loop Tool for a Fuel Cell Hybrid System Emulator Test Rig

The Thermochemical Power Group of the University of Genoa built a complete Hybrid System emulator test rig constituted by a 100 kW recuperated micro gas turbine, an anodic circuit (based on the coupling of a single stage ejector with a stainless steel vessel) and a cathodic modular volume (located between the recuperator outlet and combustor inlet). The system is sized to consider the coupling of the commercial micro turbine, operated at 62 kW load, and a planar Solid Oxide Fuel Cell (SOFC) to reach the overall electrical power output of 450 kW. The emulator test rig has been recently linked with a real-time model of the SOFC block. The model is used to simulate the complete thermodynamic and electrochemical behavior of a high temperature fuel cell based on solid oxide technology. The test rig coupled with the model generates a real-time hardware-in-the-loop (HIL) facility for hybrid systems emulation. The model is constituted by a SOFC module, an anodic circuit with an ejector, a cathodic loop with a blower (for the recirculation) and a turbine module. Temperature, pressure and air mass flow rate at recuperator outlet (downstream of the compressor) and rotational speed of the machine are inputs from the plant to the model. The turbine outlet temperature (TOT) calculated by the model is fed to the machine control system and the turbine electric load is moved to match the model TOT value. In this work different tests were carried out to characterize the interaction between the experimental plant and the real-time model; double step and double ramp tests of current and fuel characterized the dynamic response of the system. The mGT power control system proved to be fast enough, compared to the slow thermal response of the SOFC stack, and reliable. The hybrid systems was operated at 90% of nominal power with about 56% of electrical efficiency based on natural gas LHV.