Detecting development scenarios of dynamic events in electric power network smart-grids.Part two“Selective Protection”

Abstract

When implementing development concepts in the electric power industry (such as “Smart Grid”, “Digital substation” and “Outsourcing of services”), the task of ensuring stable relay protection operations and automation devices is urgent. The problem is solved according to the developed structural-information (SI) method. A method for selective search of the optimal amount of structured information for automatic decision-making is proposed. The article discusses an algorithm for recognising scenarios for the development of semantic events, which is included in the SP-method. The algorithm is applied uniformly for all hierarchical levels of recognition, based on the goals of decision making at the senior level. Control of the sequence of information events is performed in the dynamics of the passage of events along one path from all relationships according to the structural-information model. Part 1 shows a collaborative structural-information model consisting of a shaping tree in a dynamic object and a recognition tree in devices. A theoretical description of the algorithm is given using the amplitude and time (Ξ,Η) selectivity windows in the general structural scheme of S-detection. The application of the method for different hierarchical levels of recognition is shown. The decision-making results are presented in two forms, by means of a single semantic signal to indicate a group of results and filling in the table of the sequence of occurrence of the recognised elementary information components. Part 2 shows the application of the SPmethod at different hierarchical levels of recognition for the synthesis of a selective relay, which implements an algorithm for finding a damaged network section with single-phase ground faults in 6-35 kV distribution networks with a Petersen’s coil. The reasons for the unstable operation of algorithms of known selective relays are indicated, based on the concepts of scenario recognition. The improvement of the structure of a selective relay operating on the basis of the criterion for monitoring the coincidence of the first half-waves of the mid-frequency components in the signals of transient processes is considered. Examples of the synthesis of elementary detectors of absolute, relative and cumulative actions in relation to a selective relay are given, which make it possible to fill the amount of information for general S-detection. The simulation of the operation of the synthesised S-detector on the signals of real emergency files of the natural development of damage to the isolation of the network phase and simulation of artificial scenarios of events in the mathematical SI-model are carried out.