Evaluation and control of heating effect due to harmonics in motor loads

Using circuit analysis, it is shown that it is generally not possible to attribute precisely the power contributions from harmonic sources in loads. A harmonic power flow control scheme is proposed instead so as to reduce the harmonic heating effect in motor loads and thus increase the lifetime of the motors. The technique is based on the sensitivity measure of harmonic real power in the motors to the source harmonic current injections. The net benefit in the control strategy is the economic gain resulted from the increase in motor lifetime against the cost incurred in controlling the harmonic power flow. The objective is to arrive at a harmonic power flow strategy to maximize the benefit.