Software for detection and storage of fault records
An important function of digital protection is to store disturbance records for more accurate analysis of critical events in the grid. As the memory for such records is limited in the relay it has shown convenient to extract them by use of standardized communication and store them on a hard disk on station level for further use. Serial communication of digital protective devices to Substation Control Systems has been standardized and published as IEC standard protocol 60870-5-103. Recently the new standard for power utility communication IEC 61850 has added much more flexibility and performance to data exchange with different IEDs.
SICAM DISTO (disturbance data storage) is a software package, which recognizes the occurrence of new disturbance records in the connected protection relay fetches them by means of substation communication and stores them in preconfigured directories on the hard disk of a PC. For easy analysis with different tools DISTO uses the standardized OMTRADE – format for all disturbance files according to IEC 60255-24). Whereas DISTO has to translate incoming disturbance records from IEC 60870-5-103 into COMTRADE, the transmitted files in IEC 61850 are already in the right format.
Some protection relays send COMTRADE files packed in zip files over IEC 61850. SICAM DISTO recognizes such files and unpacks them into the right directories. Using IEC 61850, SICAM DISTO expects the transmission of fault records per MMS. The option with FTP is not supported. If using IEC 60870-5-103, DISTO prepares in addition an event list with all protection-relevant information, such as fault number, fault distance etc., both with absolute and relative real time (within a storing disturbance).
The stored files contain the time dependent behaviour of currents and voltages before, during and after a disturbance in the grid, plus additional events (e.g. trips). These data can be displayed as graphs on screen using SIGRA or other software tools with analyzing functions.
For accessing the communication to the relays, DISTO makes use of SICAM 230 or 250 SCALA and their integrated communication drivers. Remote access to the stored files is available by use of standard tools of the operating system.