Mitigation of ripple control signal amplification with LV harmonic filters

Audio frequency ripple injection systems have been used for many years to control load on distribution networks. However, distribution utilities often experience some practical issues with their audio frequency systems due to harmonic interference and network resonance. Network resonances are generally very difficult to rectify as distribution networks are very dynamic and can change on a daily basis. This paper presents a case study where ripple signal amplification was resolved through the use of a low voltage tuned filter. Filter design was supported by the development of a three-phase model of the distribution network using the Alternative Transients Program. This modelling has demonstrated that distribution feeder resonance can be predicted and that the installation of a tuned filter can attenuate the ripple voltages to acceptable levels on the low voltage network.