The problem of proper quality of primary and secondary frequency and power flows regulation in IPS of Ukraine is considered in the context of an increase in the share of renewable energy sources in the energy balance of the IPS of Ukraine. An approach and criteria have been developed for determining the optimum value from the technological point of view and the allocation of power reserves in the Ukrainian Interconnected Energy System on reconstructed and non-reconstructed units/aggregates of thermal power plants and hydroelectric power stations. Based on the results of IPS regimes simulation modeling in cases of sudden, likely by criterion N-1, imbalances of active power, a list and the need to attract non-reconstructed units/aggregates of power plants to primary and secondary load-frequency regulation is determined. References 10, table 1.

Purpose. A review of the current literature, regarding the existing approaches used to estimate the lightning perfor-mance of overhead power lines, was performed. A review of available lightning activity data over India was also per-formed. Methodology. The electro-geometrical model was chosen to analyze the lightning performance of overhead power lines. International normative documents and national standard were used to highlight the main parameters that should to be paid main attention to when estimating lightning performance of overhead power lines. Results. Presently, approaches from IEEE and CIGRE guides can be used for analysis of statistical distributions of lightning current pa-rameters. Further studies are required on thunderstorm days, ground flash density and current parameters statistical dis-tributions for different locations, which will be supportive in performing analysis for Indian power lines. Originality. To graphically analyze the shielding failure mechanism with a help of electro-geometric model, the sketch of real 220 kV double-circuit transmission line tower was used. Using electro-geometric model it was graphically shown how downward lightning leader that propagate from thunderstorm cloud toward ground can finish its path on the overhead shield wire, phase conductor or ground plane. Practical value. Available data on lightning activity over different parts of India are still not enough complete. It is of great importance to obtain reliable statistical data on thunderstorm characteristics in the area of the studied power line route. Measurement techniques based on satellites have limitations in obtaining ground flash density values. Thus, for India there is a need in development of modern lightning detection networks and related studies on lightning characteristics. Conclusions. Future efforts should be focused on obtaining not only the positions and number of lightning strikes to the overhead power line, and calculation of lightning flashover rate parameters, but also the statistical distributions of lightning current values and related overvoltage parameters at the overhead wires and different phase conductors. References 21, figures 4.

Purpose. The method for calibrating an experimental installation for studying the patterns of partial discharges aris-ing in samples of paper insulation having low capacitance was developed. Methodology. In order to verify the proposed method, a physical experiment was carried out in a high-voltage laboratory to measure partial discharge parameters using a digital oscilloscope. Free software for circuit simulation was used to create high-pass filter schematics. Results. The task of calibrating the systems for measuring partial discharges of low capacitance insulation samples (for example, ranging from 1 pF to 5 pF) is characterized by high complexity, because the calibration capacitor must have a capacitance an order of magnitude smaller than the capacitance of the test sample (from 0.1 pF to 0.5 pF, accordingly), which sometimes cannot be achieved practically. Moreover, in such case the stray capacitance will obviously be of the same order as the capacitance of calibration capacitor, or even greater. In such cases traditional calibration circuits where calibration generator is connected in parallel with the test object cannot be applied. Originality. Alternate calibration circuit was proposed, implemented and tested in the work, where the calibration generator is connected in series with test object. Practical value. Studies of the proposed calibration method have shown that it can be used quite effectively in cases when test object have low capacitance. The results of recording the calibration pulses showed that they can be reliably recorded and measured with a minimum error (oscilloscope error), and errors associated with parasitic parameters of the recording circuit are automatically taken into account when calibrating by this method and do not require additional adjustments. Conclusions. There is a possibility to increase the sensitivity of the measuring circuit to 0.05 pC/V, primarily by increasing the gain of the oscilloscope at least 100 times without repeating the calibration procedure. This will make it possible to study insulation samples of fairly high quality in which the level of partial discharges is much lower than in those samples used in this work. The experimental installation can be used to analyze different ways of modeling partial discharges on a personal computer and comparing their results with a real experiment. References 15, figures 12.

Purpose. The article discusses new strategies for controlling distribution networks with different, active components using synchronized measurements of voltage and current phase values (magnitude and phase angle) based on the use of high precision micro-synchrophasors (uPMUs), which are adapted to work in distribution networks. Particular attention in the article is focused on the problem of mislabeling of phases and load balancing of distribution network feeders. Methodology. Elements of the optimization theory and matrix calculation were used to develop optimization criteria for initial load balancing problem and minimum switching load balancing problem. Results. The article considers approaches to solving problems arising in distribution power grids under conditions of growth of distributed generation levels. The factors leading to increased uncertainty in forecasting distribution network modes that complicate the tasks of power equipment diagnostics, network topology identification, state assessment and fault location are established. Problems of incorrect phase marking and load symmetry of distribution network feeders are analyzed in detail. Authors proposed an approach to phase identification and feeder load symmetry using micro-synchrophasor data (uPMU) based on the analysis of voltage measurements. The proposed approach is based on comparing the measurements made at the beginning of the feeder with the measurements made in other locations of the feeder considering the constant phase angle shifts of voltage multiples of 30 degrees, which are caused by the phase shift of transformers. The peculiarity of the proposed approach is the ability to solve the problem of phase marking and phase identification using the measuring bodies of uPMUs with accuracy within 1 degree. As a result, based on the information about the actual phase markings, the authors proposed an approach to feeder load symmetry, which is based on solving the optimization problem. The optimization criterion is the minimum by the sum of the norms of the vector of the feeder phase loads for a certain period of time. This article investigates an approach to phase identification in three-phase distribution networks based on the analysis of micro-synchrophasor measurements (uPMU). The proposed approach is based on direct voltage measurements at different feeder locations, taking into account the fact that in an unbalanced three-phase system the time series voltage values at the two ends of one phase should have a much stronger correlation than at the two ends of different phases. This feature makes it possible to solve the problem of marking and identification of phases when using uPMU measuring bodies with accuracy within 1 degree. The proposed approach takes into account, in multiples of 30 degrees, the phase shift due to the presence of D-Y transformers. The proposed approaches will be investigated when creating a monitoring system for electric distribution networks using uPMUs at the pilot site of the Igor Sikorsky KPI campus and elsewhere in cooperation with network operators. Originality. In contrast to the known methods and approaches to the phase identification, proposed method using direct measurements of three phase voltages and thus obtained results do not contain uncertainty. Practical value. Solving the phase marking problem also reduces the number of errors in power equipment diagnostics, network topology identification, condition assessment and fault location. References 11, figures 4.