TABLE OF CONTENTS The electrical power distribution network in the UK is a distributed grid of high power components. The grid is controlled hierarchically with, at the lower level, proximal components being grouped around substations which contain not only protection elements but also sequencing and timing logic. At the next level up the substations feed to a control centre which, for historical reasons, can be viewed in terms of a number of different geographical areas, each area control containing its own regional substations.
When a fault occurs on the transmission network, automatic protection and isolation occurs at a number of substations, opening switches to ensure that power is no longer fed to the faulty line, and that the disturbance on the remainder of the grid is effectively minimised. Details on which of the switches have operated are passed on to the control centre which continually polls round the different substations to see what switchgear information each has.
No direct information is obtained on what type of fault has occurred and where, but rather information is obtained in the control centre which indicates which switches and automatic protection devices have operated in response to the fault.
The switching messages, along with further analogue information, can be regarded as symptoms , whose cause can be inferred from the overall message pattern. Unfortunately interpretation of the messages depends on such variables as network topology, the current network state, and which intertrips are in service. All of these go together to make...
