JWG C4/B4.38 Network Modelling for Harmonic Studies

Background :

Power system performance issues associated with steady-state harmonic voltage distortion is becoming even more pronounced as connection of nonlinear devices and/or loads increases driven by integration of renewable energy sources and connection of new HVDC converters. Proper harmonic voltage distortion performance specification is therefore crucial as it impacts the subsequent design of harmonic filters. In order to draw up proper specifications or limitations to coordinate the emission of harmonics onto the system, the vast majority of cases require proper modelling of the power system for this purpose. This in turn suggests the need for an appropriate model for each individual electrical plant. For example, the effect of resistive damping provided by certain plants is often ignored and it is important to establish clear guidelines as to how this should be taken into account. Availability of information and guidance for such modelling requirements are either scarce or in scattered form, mostly delegated to appendices of various documents (examples are the short articles in Electra 164 and 167 published in 1996 and the recent TB 553). The source of many of these models has been lost in history, and reference can only be made to publications, some of them by CIGRÉ, which contain formulae for the representation of network components but with little or no proof of derivation. Both Electra articles are authoritative in nature but suffer from the issues outlined above, and are also becoming outdated and inaccessible. There is also a lack of guidance on the way of treating existing nonlinear loads embedded into the network. Loads at low voltages are usually not part of the larger transmission models and hence it is desirable to know the most suitable voltage level these should be connected to as an equivalent and how that equivalent should be represented. Therefore, there is a need for collating all the available information in the literature and formulating a study and modelling guidance document for practising power system engineers while performing harmonic voltage distortion analysis.

Scope :

1. Collate and provide all available information in the literature on modelling individual electrical plant including equivalent loads for harmonic voltage distortion analysis purposes.

2. Evaluate and suggest best practice in the use of available models to modern equipment.

3. Identify any shortfalls with available models and the possible need for further development in this area.

4. Provide clear and concise guidelines on modelling existing nonlinear loads (HVDC converter station, wind farm generation etc) within the system of interest. Approach manufacturers to identify suitable harmonic models for equipment where appropriate.

5. Provide guidelines on general approach to such studies and the availability and choice of tools. Identify any shortfalls with the available analysis tools and suggest possible developments.

The JWG will also work closely with SC B1 and seek two qualified experts from SC B1 as members of this JWG given the fact that high-voltage insulated cables do also have a significant impact on power system performance issues related to harmonics.

Convener:M. Val Escudero (Ireland)


Progress Report 2014 (pptx, 139kB)

Progress Report 2015 (pptx, 140kB)

Progress Report 2016 (pptx, 144kB)