MRN3-3 – Mains decoupling relay

The mains decoupling relay MRN3-3 has been designed for the use under special conditions, especially to be found at wind parks. If power generating systems are due to comply with the GridCodes, i.e. if they shall not immediately disconnect from the grid in case of a mains failure, but support it, instead, the MRN3-3 will be the optimal relay. Its' function is to supervise mains voltage and mains frequency in compliance with the GridCodes, the grid connection rules and the operator guidelines. For this reason, the distinction between short-distance or long-distance errors is an elementary fact. As per the requirements of the e-on grid connection rules (version dd. 20.08.03) and the VDN guideline “EEG power generating plants at high and maximum voltage systems”, in addition to the standard protection functions, the MRN3-3 provides the voltage time characteristics which are necessary to distinguish between short distance and long distance errors. Normal voltage collapse shapes at mains failures are taken into account by these characteristics, that allow selective disconnection of systems only there, where it is absolutely required for operation. If, in the event of a failure, the systems are to be connected to the grid for a longer period, they will support the mains voltage and thus avoid large-area breakdowns that could no more be compensated by the interconnected network's primary control reserve. Thanks to the presence of two independent characteristics, it is possible to distinguish between short-term or permanent interruption, each according to the type of error. In the event of a failure, the fault sequence can be recorded by an oscilloscope. Within this error scenario, the MRN3-3 with its characteristics hat have been applied for the first time in protection technique - is of enormous use for the accurate identification and analysis of the grid state - as demanded by the rules.

FEATURES & FUNCTIONALITY

The mains decoupling relay MRN3-3 has been designed for the use under special conditions, especially to be found at wind parks. If power generating systems are due to comply with the GridCodes, i.e. if they shall not immediately disconnect from the grid in case of a mains failure, but support it, instead, the MRN3-3 will be the optimal relay. Its' function is to supervise mains voltage and mains frequency in compliance with the GridCodes, the grid connection rules and the operator guidelines. For this reason, the distinction between short-distance or long-distance errors is an elementary fact. As per the requirements of the e-on grid connection rules (version dd. 20.08.03) and the VDN guideline “EEG power generating plants at high and maximum voltage systems”, in addition to the standard protection functions, the MRN3-3 provides the voltage time characteristics which are necessary to distinguish between short distance and long distance errors. Normal voltage collapse shapes at mains failures are taken into account by these characteristics, that allow selective disconnection of systems only there, where it is absolutely required for operation. If, in the event of a failure, the systems are to be connected to the grid for a longer period, they will support the mains voltage and thus avoid large-area breakdowns that could no more be compensated by the interconnected network's primary control reserve. Thanks to the presence of two independent characteristics, it is possible to distinguish between short-term or permanent interruption, each according to the type of error. In the event of a failure, the fault sequence can be recorded by an oscilloscope. Within this error scenario, the MRN3-3 with its characteristics hat have been applied for the first time in protection technique - is of enormous use for the accurate identification and analysis of the grid state - as demanded by the rules.