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UT Power Engineering Laboratory - "Powering the Future "

Reliability of Power Semiconductors in a STATCOM


Dr. Leon M. Tolbert
Lakshmi GopiReddy


Reliability is a matter of concern in power systems integrated with Smart Grid (SG) technology and there is a need to study the individual reliability of grid-connected devices/systems such as STATCOM, PMU etc. to predict their impact on the grid, also emphasized by North American Electric Reliability Commission (NERC). This research mainly focuses on the reliability of power semiconductor devices, and IGBT devices in particular, used in the power electronics integrated with power systems. Since most of the common failures (wire bond and solder fatigue) are caused by thermo-mechanical stresses, the methodology of lifetime estimation starts with temperature estimation, cycle counting based on rainflow algorithm, and finally degradation calculation based on linear accumulation model.

Temperature of IGBTs in a module is estimated when the STATCOM is operating in power factor correction and harmonic compensation modes. A novel rainflow algorithm with faster execution time is proposed for cycle counting. A universal lifetime model based on dimensions and operating conditions is proposed to estimate lifetime by simplifying Finite Element Analysis (FEA) by basis function quadratic relationships. Finally, the life of IGBT is estimated during STATCOM operation using real-time load profiles for power factor variation.

Related publications and presentations

1. L. GopiReddy, L. Tolbert, B.Ozpineci, Y. Xu, T. Rizy, Impact of Power Factor Correction and Harmonic Compensation by STATCOM on Converter Temperature and Reliability, IEEE Energy Conversion Congress and Exposition, Phoenix, Arizona, Sept.17-22, 2011, pp. 1928 – 1934.

2. L. GopiReddy, L. Tolbert, B.Ozpineci, Y. Xu, T. Rizy Reliability of IGBT in a STATCOM for Harmonic Compensation and Power Factor Correction, 2012 Twenty Seventh Annual IEEE Applied Power Electronics Conference and Exposition, APEC, 2012, Florida, pp. 783-788.

3. L. GopiReddy, L. Tolbert, B.Ozpineci, Lifetime Predicton of IGBT in a STATCOM using Modified Rainflow Counting Algorithm Annual Conference of the IEEE Industrial Society Conference, Oct. 25-28, 2012 (Accepted).

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