Determination of the design parameters of passive harmonic filters using nonlinear optimization

Power system harmonics are a menace with disastrous consequences. A number of ways were tried out to tackle the harmonic problem posed by nonlinear electric devices, but by far, the most popular and quite effective one is the use of passive filters. This provides a low impedance path to a harmonic or a group of harmonics. Usually the AC harmonics are odd harmonics. So normally the filter combination selected is such that for the predominant harmonics, one or more single tuned filters are used, and for the rest of the harmonics, a high pass filter is used. An alternate combination is that a damped filter is used for the two predominant harmonics with the filter being tuned at a frequency in between the two harmonics and another damped filter for the higher harmonics. If all the harmonics are not of very high magnitude then usually one high pass filter is sufficient for all the harmonics. Instead of the conventional design of these filters, which is based on experience of the designer, a better way is to use the optimization algorithms to obtain maximum performance from these filters.