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WG C4.45 Measuring techniques and characteristics of fast and very fast transient overvoltages in substations and converter stations

Background :
Recorded electromagnetic transient voltage waveforms appearing on power network plant in substations and converter stations are valuable resources in developing acceptable high-voltage dielectric test methods, economic insulation design schemes, and so on. However, recent years have seen integration of new power equipment and application of new transmission technologies. Hence, fast and very fast transient switching and lightning overvoltage waveforms observed at substations and converter stations are much different from the standard switching and lightning waveforms specified in the existing high-voltage test standards in most cases. Furthermore, there is very little or no information at all on the characteristics of fast and very fast transient overvoltages.
Fast and very fast transient overvoltage waveforms in raw form, prior to grid faults include crucial information and are the key to revealing the causes, and avoiding the same types of faults from happening repeatedly. Unfortunately, performance of the existing voltage recording devices in substations or converter stations are in the majority of cases not able to satisfy the requirements for recording fast and very fast transient overvoltages accurately.

Scope :
It is proposed to establish a working group to produce guidelines on functional specifications, performance requirements and tests of measuring devices for fast and very fast transient overvoltages encountered in substations and converter stations. The main tasks of this WG are as follows:

  1. 1. Review measuring techniques for fast and very fast transient overvoltages around the world, and present the technical features and applicability of the state of the art of measuring techniques.
  2. 2. Carry out research on novel measuring techniques for fast and very fast transient overvoltages so that functional specification for such measurements can be drawn up.
  3. 3. Specify performance requirements for applicable measuring devices along with necessary test methods such that measurements from different devices are comparable. Proposals on the tests will extend to response speed, bandwidth and accuracy of the measuring devices.
  4. 4. Monitor the lightning overvoltages appearing on power equipment in substations and converter stations and collect the lightning overvoltage waveforms.
  5. 5. Measure the fast and very fast transient switching overvoltages in substations with voltage classes from 110 kV to 1000 kV and in converter stations with voltage classes of ±500 kV and ±800 kV.

Convener: Shijun Xie (CN)