Fuzzification of protection settings — A new method for the evaluation of a nationwide protection system

The analysis and interpretation of the quality of a nationwide protection system is challenging. This paper presents a new method for an automated analysis of the protection system of electrical energy systems. The intent was to find a fast and holistic approach. The holistic requirement is fulfilled by analysing all relays locally and in dependency to the surrounding ones, whereas more than just selectivity of the protection settings is considered. This means a linguistic-like interpretation of the protection settings. A fuzzy system was developed therefore. The use of fuzzy logic enables the possibility of integration in an automated application. Based on expert-knowledge this fuzzy system acts similar but faster compared to a real expert and hence fulfilling the second requirement of being fast. To prove the benefit of this theoretical approach a comparison has been done between the fuzzy system and the commonly proofed method finger-print analysis. This paper demonstrates the capability of the presented method to analyse the settings of a protection system, to find its weak spots, to identify the reasons in detail and to calculate the result very fast.