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This work is devoted to the research of the real-time estimation of 500 kV power transmission lines parameters with PMU based on the solution of the optimization problem of minimizing the root-mean-square deviations of the specific line parameters or the sum of the modules of the correlation coefficients between the specific parameters and the sum of the squares of the voltages or currents measured at the ends of the line. Independent optimization variables are the correction factors of the measuring systems of currents and voltages. Based on an artificially simulated PMU dataset with specified Gaussian noise and systematic errors, it is shown that the use of correlation coefficients in the objective function is more effective than standard deviations. All 5 estimated coefficients turned out to be closer to the reference values. The results of calculations are obtained from the data of real PMUs for an operating 500 kV line with a length of 504.6 km. The deviation of the specific capacitive conductivity from the nominal value is 0.13%, compared with - 0.29% when using the sum of squares of deviations as an objective function.

The article presents the dependences of the active and reactive components of the losses of the idle transformer on the mains voltage. It is proposed to evaluate the no-load losses using an alternative method for identifying the parameters of the transformer based on high-precision synchronous measurements. Within the framework of a pilot project on a real feeder, using the technology of synchronous measurements, the dependences of no-load losses on voltage were identified. For transformers installed in a distribution network, the dependence of losses on voltage is not quadratic, but has a higher order. It was determined that the dependence of losses in a transformer on voltage for active power has a power of 6.35, and for reactive power has a power of 7.4.

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Aim. The aim of this study was to investigate the influence of zinc supplementation on the development of thymic involution during the growth of transplantable tumor in mice. Materials and methods. Inbred C3HA mice after subcutaneous syngeneic hepatoma 22a inoculation received zinc sulfate with drinking water. After 3 weeks of tumor growth animals were killed, and evaluated for zinc content in serum blood samples, thymus status and parameters of tumor growth. Results. At the 21 day of tumor 22a growth weight and cellular content of the thymus were decreased by 3 times and endogenous zinc content in samples of blood serum was decreased by 1,9 times. Oral zinc sulfate supplementation at concentration of 22 mkg/ml in drinking water during 3 weeks, started from the first day after tumor inoculation, increased thymus weight and cellularity as well as serum zinc content. At the same time, it did not influence tumor size and survival rate of mice with hepatoma 22a. As a possible mechanism of zinc action, we studied the influence of zinc supplementation on the activity of two anti-oxidative defense enzymes: Cu,Zn-superoxide dismutase and catalase in the thymus. Zinc supplementation had no influence on these parameters, both remained at a higher level in tumor-bearing mice. Conclusion. Oral zinc supplementation in hepatoma 22a bearing mice induced retards the development of thymic involution with no influence on the tumor growth per se. The study allows to suggest that oral zinc administration may be considered as a prospective strategy for thymus reconstitution in oncology patients.