IREMENTS F FOR PEOP PLE AN ND ELECT TR RICA AL EQUIP PMENT IN N SMART T G GRI IDS

With the integration of Smart Grid technologies (intelligent components and decentralized sources) into medium and low voltage grids issues regarding safety requirements for people and electrical equipment emerge. The basic topic for new requirements is that decentralized power generators combined with substation transformers can lead to an indefinite bidirectional fault current flow. Furthermore different initial short-circuit powers of substation transformers and decentralized power generators can cause a change of direction and magnitude of the short-circuit currents. If the initial short-circuit power is not achieved existing protection devices are not sufficient and new requirements concerning the protection system appear. Therefore a significant question arises: Is it possible to maintain personal safety and furthermore the functionality of protection systems in case of a fault? Exemplarily studies on a five-wire installation system including the simulation of characteristic network systems, substation transformers, decentralized power generators and protection systems have to be done. Additional characteristic elements for the experimental test setups are loads (1- and 3-phase), switching elements and electrical protection devices (additional protection, RCDs). Considering changing short-circuit currents (bidirectional current flows) the existing protection concepts have to be examined on functionality and on the advanced requirements in case of decentralized power generators. To avoid endangering the personal safety knowledge of fault voltages and hence touch voltage in dependency of the resistance of the contact current circuit are of interest for further considerations.