EGÚ Brno (Czechia)

The planned phase-out of coal power plants connected to transmission and distribution networks 110 kV is associated with the task of substitution of current active and reactive sources with new ones, based on an innovative technology. The new connected sources are mainly decentralized, renewable and are based on the non-synchronous power modules connected particularly to distribution networks (MV and LV). This influences their capability for reactive power operation. Improvement recommendations for the reactive management in distribution and interface transmission/distribution systems are presented based on wider technical studies in cooperation with TSO and DSOs in the Czech Republic.

The refurbishment of distribution network assets is usually based on long-term strategies which the distribution system operator formulates for particular asset groups. One of the important asset groups (particularly in urban networks) consists of MV/LV distribution transformer stations (DTSs). The strategy of their refurbishment could rely on a simple refurbishment (i.e. on replacement of equipment with a functionally identical unit), but with regard to the smart grid trend, the refurbishment tends to be extended by installing the telecontrol as well as measuring and signalling devices. However, for the complete formulation and evaluation of the strategy, even in the case of the extended refurbishment, there are a number of questions to be answered. The study shows possible refurbishment strategies of DTSs in case of a large urban distribution network, picks up some details of carrying out the strategies by an algorithm and presents the specific approach to related reliability simulation.

This paper deals with a comparison of an optimal solution of equipping a MV distribution network when different financial equivalents of supply interruption are taken into account. The comparison elicits from the optimization studies performed for real feeders of 22kV overhead lines. The reliability of each feeder section is simulated by the non-sequential Monte Carlo method. Statistical distributions used in the simulation are based on a failure database covering a 10-year period. The comparison is carried out for an optimization task whose objective is allocation of telecontrolled switching elements (telecontrolled section switches and reclosers). The results are presented for a single feeder and for a representative set of real feeders. Due to the fact that the selection of the financial equivalent of supply interruptions (the value of supply interruption) is strongly connected to a regulation framework, current regulation of supply continuity in the Czech Republic and its expected evolutions are summarized.