Abstract. The paper gives description of customer dissatisfaction index (CDI) that can be used as reliability level characterizing factor. The factor is directly joined with customer satisfaction of power supply and can be used for control of reliability level of power supply for residential customers. CDI relations with other reliability indices are shown. Paper also gives a brief overview of legislation of Latvia in power industry that is the base for CDI introduction. Calculations of CDI improvement costs are performed in the paper too.

The estimation of power supply interruption costs was performed in Latvia in 2012, in the framework of a survey study (the first officially recognized study of interruption costs in Latvia since restoration of Independence in the early 90's). The survey involved ~ 3000 end users, which are classified as the major electrical energy consumers in the country. As a result, the customer damage functions (CDFs) and the functions of cost deviations depending on the interruption occurrence time have been created. The study is unique not only for Latvia, but also for the whole Baltic region. The information obtained is usable for improving the quality of supply regulation (also known as Performance Based Regulation (PBR)) and for planning and running the power networks.

Estimation of Economical Validity of Usage Remote Operated Disconnectors for 110kV Switchgear Schemes From Optimal Reliability Level Point of ViewThe paper gives results of technical and economical calculations performed for estimation of validity of usage remote operated disconnectors for most commonly used 110kV switchgears from optimal reliability level point of view. Paper contains description of performed technical calculations - calculations of 110kV switchgear schemes' reliability level depending on type of disconnectors installed, and economical calculations, that are related with additional costs of Transmission System Operator and changes in total customer costs of power supply interruptions.

The paper presents the main goals and achievements of the SmartGrids ERA-NET project named "Efficient Identification of Opportunities for Distributed Generation Based on the Smart Grid Technology (SmartGen)" during two years of project realization in Latvia.In the paper we proposed the basic principles of optimization of hydro power plant (HPP) working conditions under forecasted electricity prices and probabilistic water inflow values, as well as assessment of the impact of asynchronous generator connection to the existing network taking into account technical limitations.The developed model considers the most important technical parameters of HPP and the network, allowing to make HPP generation forecasts and its impact on the network using time-varying and constant input parameters. The mathematical model of a small scale HPP was developed for simulation of HPP electricity production and transient processes.The paper also includes the description and results of a case study performed to test the proposed mathematical model. The case study was carried out using the real distribution network part with the connected HPP. Different generation and load scenarios have been modelled. Load-generating interaction scenario modelling was implemented in the Matlab environment.The elaborated model can be used for representing a wide range of HPPs in electrical market and assessment analysis of the distribution network, as well as adapted for modelling of other types of power plants that use asynchronous generators.

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