Tri-axial Seismic Simulation of Solar Inverter – Productivity Improvement

Often, earthquake is a tri-axial event, as in, it excites the system in all three directions. Evaluation of big systems like high capacity solar inverters for such events through testing is quite expensive. Trend these days is to qualify the system using CAE simulation, in contrast to testing. Simulation of big systems is always a challenge, as it becomes computationally expensive due to high node count and large number of modes in the frequency range of interest. In this work, seismic analysis is performed using commercial FEA software ANSYS. Conventional way of seismic simulation in ANSYS is to first excite the system separately in the orthogonal directions and then compute the tri-axial response by superposition of responses in individual directions. In this paper, based on the response spectrum analysis, a tri-axial seismic analysis methodology is proposed and implemented on complicated high capacity solar inverters. Proposed methodology calculates a resultant mode participation factor from mode participation factors due to excitation in individual directions and then performs the mode combination. It was observed that computational time was reduced to 1/3rd without any compromise in the accuracy of response. Also, proposed simulation methodology doesn’t require separate static analysis to account for the effect of missing mass. This further increases the productivity of a seismic engineer performing a finite element analysis.