In power systems there are complex transformer structures, whose accurate analysis is not possible using the techniques available today. This paper presents a systematic data driven analysis method for coupled inductors of arbitrary complexity. The method first establishes a winding matrix N mapping the windings to the limbs of the transformer. A permeance matrix P is created from the reluctance network of the magnetic core. A generalized inductance matrix L mapping currents in the transformer windings to the induced voltages is generated based on the winding (N) and permeance (P) matrices. The inductance matrix representation of a coupled inductor is then transformed to an admittance matrix, which can be integrated to the nodal analysis of the electrical circuit surrounding the coupled inductor. The method presented is validated by simulations with real transformer structures using electromagnetic transient program (EMTP/ATP).

Estimation of the worth of continuity of electricity supply is of interest of industry, authorities and research society. There are numerous methods to calculate the Customer Interruption Costs (CICs). Each method has its advantages and disadvantages. This paper approaches the problem from Distribution System Operators’ (DSOs) point of view and adopts two existing analytical models. One model is used by the Finnish Energy Market Authority and the second one was proposed by the authors at a previous study. The model suggested by the authors as an alternative to the one used by the Finnish Energy Market Authority proposes a simple and straightforward methodology which will provide credible and objective estimations by only utilizing publicly available analytical data. We made use of cost and reliability indices data of 78 DSOs in Finland from the year 2016. In addition to cost estimations, this paper highlights regional differences in CIC estimations in different parts of Finland and critically overviews the existing standard customer compensation scheme in Finland.

Increasing distributed generation and intermittency, along with the increasing frequency of extreme weather events, impose a serious challenge for the electric power supply security. Understanding the costs of interruption is vital in terms of enhancing the power system infrastructure and planning the distribution grid. On the other hand, customer rights and demand response techniques are further reasons to study the worth of power reliability. In this paper, the authors make use of directional distance function and shadow pricing method for a case study from Finland. The aim is to calculate the cost of one minute of power interruption from the distribution network operator perspective. The sample consists of 78 distribution network operators from Finland with cost and network information between 2013 and 2015.