The ultimate fault analysis system should provide results of a detailed system-wide analysis of an event to the system dispatchers and protection engineers within seconds after the event occurred. This may not be feasible with the existing SCADA technology. The main reason is the lack of detailed information about transient waveforms and contact changes that are not readily available through Remote Terminal Units (RTUs) of a SCADA system. On the other hand, such information is available through other Intelligent Electronic Devices (IEDs) including DFRs, Sequence of Event Recorders (SERs) and Digital Relays (DRs). A new concept for fast and accurate fault analysis can be developed using this equipment technology, high-speed data communication infrastructure and advanced software techniques.

Various types of users have different needs regarding the time response and/or extent of information provided by the fault analysis system. The system dispatchers are interested in getting the condensed fault analysis information as soon as possible after the valid fault occurs. Their main interest is determination of accurate fault location and switching equipment status that enables them to make decisions about the system restoration. The protection engineer, on the other hand, is more interested in getting detailed and specific information regarding the operation of the protection system and related equipment during the event. The time factor is not as strict as for the system dispatcher.

In this section we present the concept of an integrated fault analysis system that can be built with existing technology and can satisfy both types of users. The subsequent sections give brief presentations of various research and development projects (see Project I, or Project II) that are an illustration of possible steps towards the final system solution for automated fault analysis.

It is important to note that such an integrated solution is not yet available since the design provisions to implement the synchronized sampling for all substation data acquisition systems are not readily available. In addition, utilities are still researching various options to provide standard communication architecture allowing high-speed substation-wide data acquisition and transfer to the centralized substation and system level location.

An assessment of the existing technology reveals that future developments in the IEDs for substation metering, control and protection are leading to the following expected improvements:

Increased accuracy of the A/D subsystem

Synchronized sampling on all input channels

Multiple communication interfaces for high-speed data transfer

Availability of extensive signal processing for calculation of various measuring quantities

Combined with on-going developments in the utility communication architecture, it is expected that the substation IEDs will provide an impressive level of detail of the data needed to perform automated fault analysis.

In the meantime, some solutions that are less involved can be implemented using the technology that is readily available. In particular, DFR data analysis can be automated using expert system technology. In addition, fault location accuracy can be improved using GPS receivers to synchronize customized data acquisition units located at two ends of a transmission line.