The concept of price elasticity of demand has been widely used for the assessment of the consumers’ behavior in the electricity market. As the residential consumers represent a significant percentage of the total load, price elasticity of their demand may be used to design desirable demand side response programs in order to manage peak load in a power system. The method presented in this study proposes an alternative approach towards price elasticity determination for zonal tariff users, based on comparisons of load profiles of consumers settled according to flat and time-of-use electricity tariffs. A detailed explanation of the proposed method is presented, followed by a case-study of price elasticity determination for residential electricity consumers in Poland. The forecasted values of price elasticity of demand for the Polish households using time-of-use (TOU) tariff vary between −1.7 and −2.3, depending on the consumers’ annual electricity consumption. Moreover, an efficiency study of residential zonal tariff is performed to assess the operation of currently applicable electricity tariffs. Presented analysis is based on load profiles published by Distribution System Operators and statistical data, but the method can be applied to the real-life measurements from the smart metering systems as well when such systems are accessible for residential consumers.

This paper presents novel zero sequence current filter and earth fault protection relay, which utilize cable screens earthing current in protection algorithm. Different problems connected with state of the art of zero sequence current filters and protection relays are presented and compared with the proposed solution. The presented concept is verified in PowerFactory simulation software, experiment concerning modeling the earth fault current flow in medium voltage (MV) cable supplied from the low voltage (LV) network and measurements in the MV network in the Polish distribution system. The proposed solution is characterized by higher sensitivity and reduced number of erroneous trips. The presented solution is suitable for any MV cable lines. Biggest advantages are observed in power output lines from renewable energy sources, which are often operated under no-load conditions.

Demand side response is becoming an increasingly significant issue for reliable power systems’ operation. Therefore, it is desirable to ensure high effectiveness of such programs, including electricity tariffs. The purpose of the study is developing a method for analysing electricity tariff’s effectiveness in terms of demand side response purposes based on statistical data concerning tariffs’ use by the consumers and price elasticity of their electricity demand. A case-study analysis is presented for residential electricity consumers, shifting the settlement and consequently the profile of electricity use from a flat to a time-of-use tariff, based on the comparison of the considered tariff groups. Additionally, a correlation analysis is suggested to verify tariffs’ influence of the power system’s peak load based on residential electricity tariffs in Poland. The presented analysis proves that large residential consumers aggregated by tariff incentives may have a significant impact on the power system’s load and this impact changes substantially for particular hours of a day or season. Such efficiency assessment may be used by both energy suppliers to optimize their market purchases and by distribution system operators in order to ensure adequate generation during peak load periods.

The paper presents the possibility of using cable screen earthing current measurements for MV, single-core cable line monitoring. Cable screen earthing current measurement allows the condition of cable screen connections, degradation of earthing systems, and the earthing system integrity to be observed, which allows a condition based maintenance (CBM) strategy to be introduced for cable screens and earthing systems in MV networks. CBM allows the workload and failure rate to be reduced. Analysis of the condition of the cable screen and earthing system is carried out based on the cable screen earthing current trends and rapid changes of the current. The proposed system is integrated with a state of the art advanced metering infrastructure (AMI) and uses AMI data to calculate currents flowing through cable segments of the analyzed feeder. Additionally, a system which counts thermo-mechanical stresses associated with high current incidents in cable screens is proposed. The stresses are assessed using data from conventional protection relays and the ratio of currents in the cable core and cable screens. The stresses can be used as an indicator of the cable joint condition. The presented phenomena are studied carefully in PowerFactory software. Theoretical considerations are confirmed using measurements taken in the real MV cable line. Finally, the results of a SWOT analysis are presented and future research activities are outlined.

The objective of the presented paper is to verify economically justified levels of reactive energy compensation in the distribution network in the new market conditions, including the extensive use of smart metering systems, new types of load, or distributed generation. The proposed methodology is based on the minimization of annual costs of losses caused by the flow of reactive energy to the supplied loads through the equivalent resistance of the distribution system determined on the basis of statistical energy losses in this network. The costs of losses are compared to the costs of using compensating devices expressed by the levelized costs of reactive energy generation. The results are the relations describing the optimal annual average value of the tgφ factor to be maintained by customers to optimize the cost of loss of the distribution network caused by reactive energy flows. The dependence of the optimal tgφ value on the analyzed load and network parameters is also discussed. The resulting optimal tgφ levels should be considered in the tariffication process of services offered by distribution system operators to improve capacity and limit the costs of power network operation due to reactive energy transmission.

The paper analyzes the utilization of cable screen currents for earth fault identification and location. Attention is paid on cable and mixed feeders—cable and overhead lines. The principle of operation is based on utilization of 3 criterion values: Ratio of cable screen earthing current and zero sequence cable core current—RF_110/15, phase shift between cable screen earthing current and zero sequence cable core current—α and cable screen admittance defined as a ratio of cable screen earthing current and zero sequence voltage—Y_0cs. Earth fault location is possible thanks to discovered relation between RF_110/15 and α, whereas Y_0cs allows for reliable detection of earth faults. Detection and identification are very important because it allows to increase the reliability of supply—reduce downtime and number of consumers affected by the fault. The article presents a phase to ground fault current flow for different power system configurations. At the end solution, which improves location capabilities is proposed. The solution is analyzed in PSCAD software and verified by network experiment.