Micael Hellquist - regional sales manager
In response to the growing importance of rapid and accurate location for line faults in modern transmission and distribution networks, CIGRE Study Committee B5 has set up a new working group (WG B5.52) to analyse and compare fault location technologies for AC power networks.
The group will, in particular, be considering technologies based on impedance measurement and the travelling wave principle
In addition, approaches based on the use of data relating to network topology and to recorded fault currents and short circuit levels will also be covered.
The background information relating to the formation of the group gives a good indication of the challenges it must address. In particular, it notes that fault locators that use impedance measurement are relatively straightforward and are often integrated with modern line protection devices. However, their accuracy is limited, especially in the case of high resistance faults and in situations that are influenced by mutual coupling. In contrast, fault locators that use the travelling wave principle offer high accuracy, but the propagation velocity for the line under test must be accurately known. The equipment tends to be more costly and this approach can be difficult to apply to hybrid circuits. With this approach, there is also a need for synchronisation and communication between the individual units that make up the fault location system.
The working group, whose convenor Mr Sepehr Sefidpour is a Megger engineer, recently held its inaugural meeting in Stockholm, May 2014. The tasks ahead include assessing the performance of the technologies against criteria that include availability, speed of operation, reliability, accuracy, type of equipment required, ease of implementation, adaptability to grid evolution and maintainability. The group’s work will not be limited to substation equipment, but will also include functions related to the despatch centre and back office systems.
Ultimately, the group will produce comprehensive guidelines for the application of fault location systems in transmission and distribution networks. It is anticipated that the work will take around three years to complete.