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Reliability calculations are not easy to carry out. Virtually all the available software is based on high voltage networks and is not or is hardly suitable for calculating MV networks. The available software can only be used by specialists. The execution of the calculations is labour-intensive because of the large quantity of data that have to be input. The reliability module calculates the reliability indices of meshed and radially operated MV network configurations. With this module it is possible in a relatively simple and user-friendly way to calculate the reliability of MV networks.
The reliability module calculates the failure effects of:
•single mode failure
•single mode failure plus protection failure
•common cause failure
•maintenance plus single mode failure.
The reliability module is developed on the following specifications:
•The users have a thorough basic knowledge of reliability analysis.
•The module does not compute short circuit currents. Each fault leads to tripping of a protecting device. There is no distinction between one phase and three phase faults.
•Circuit breaker faults and protection malfunction are modelled in a simple way.
•The process is modelled for a MV distribution network.
•For each component a failure rate is specified.
•The module calculates the ENS (Energy Not Served), P (Outage Probability), F (Outage Frequency) and D (Outage Duration) for each component.
•The presence of only one trouble-shooting team is modelled. Calling in two or more trouble-shooting teams is not modelled.
•Common cause failures are modelled. No common cause failures are modelled during maintenance or repair.
•Maintenance in meshed networks is modelled.
•Anticipated outage is not modelled.
•The module calculates with mean values only.
•There is no partial recovery.
Despite the low user threshold, the reliability analysis still is a difficult matter. Therefore we recommend that only specialists should interpret the results.
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