Time coordination of heterogeneous distance protections using a domain specific language

BACKGROUND: Distance protections are widely used in protection of energy transmission lines, but their time coordination is still an important and difficult problem. Inappropriate configuration leads to a hazard event: remote circuit breaker tripping provided the local circuit breaker can be opened, which severely impairs power system operation. OBJECTIVE: To describe a method and provide software tools to alleviate the hazard in power systems. METHODS: A domain specific language (DSL) for representation of a transmission line with its distance protection schema, and a translation algorithm from the DSL to probabilistic fault trees with time dependencies (PFTTDs) are employed. RESULTS: The paper presents software tools that can support power protection experts in time coordination of distance protections. The tools are based upon abstract and concrete syntax of the DSL designed specifically for the purpose of the distance protection time coordination problem. In order to render creation of power line and its protection schema models easier, a DSL-dedicated editor supporting syntax and semantic aspects of the DSL has been developed. Additionally, a translator from the DSL into PFTTD language has been implemented. CONCLUSIONS: Power system experts are enabled to perform hazard probability assessment and sensitivity analysis. LIMITATIONS: Translation supports two types of distance protections, which are: single-system relays with starting elements as well as multi-system relays without starting elements. For the single-system relay, there is one timer per relay. For multi-system relays, there is one timer for each of possibly many protection zones. Other types of protections, e.g. overcurrent are not considered.