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This paper reports the issues and challenges behind the proposal to include interharmonic limits in the next revision of the IEEE Standard 519 as discussed within the interharmonic distortion sub-group formed in the framework of the Harmonics WG (519) of the IEEE PES Transmission & Distribution Committee.

Light emitting diode (LED) lamps are now an established lighting technology, which is becoming prevalent in all load sectors. However, LED lamps are non-linear electrical loads, and their impact on distribution system voltage quality must be evaluated. This paper provides a detailed analysis of time domain and frequency domain approaches for developing and evaluating models suitable for use in large scale steady-state harmonic power flow analysis of the low frequency (LF) emission of LED lamps. The considered approaches are illustrated using four general categories of LED lamps, which have been shown to cover the vast majority of LED lamps currently available on the market. The aim is an in-depth assessment of the ability of commonly applied models to represent the specific design characteristics of different categories of LED lamps. The accuracy of the models is quantitatively evaluated by means of laboratory tests, numerical simulations, and statistical analyses. This provides an example, for each LED lamp category, of comprehensive information about the overall accuracy that can be achieved in the general framework of large scale LF harmonic penetration studies, particularly in the assessment of voltage quality in low voltage networks and their future evolution.

As measurement and communication technology improves algorithms are being developed to get more useful information from the recorded data. One such technique is transient state estimation (TSE) which estimates the node voltages at unmonitored location from current and voltage waveforms measurements recorded during a transient event. This is useful for determining the sources of disturbances. One of the previous limitations was the lumped representation of transmission lines which limited its application to distribution systems. This paper presents a new distributed parameter transmission line model using numerical integrator substitution approach for modelling the travelling wave transmission line model. The accuracy of the model is investigated for different scenarios. To do so, the proposed algorithm is applied to two test transmission systems. The results show that a good estimation is obtained with the proposed algorithm when long transmission lines are present in the system being estimated.

The paper reports an experimental evaluation of LED lamps in terms of admittance Frequency Coupling Matrices (FCM) for harmonic modelling needs. After recalling the FCM approach, a description of the experimental setup used and an LED lamp classification previously proposed by the authors is presented. For each of the four lamp types identified, some harmonic fingerprint plots are shown to introduce the admittance characteristics. More detailed analysis of the characteristics is performed using the tensor representation of the FCM, which compares characteristics between the different lamp types and also between different lamps of the same type. It is shown that this approach can identify characteristics of different types of lamps for modelling purposes.