Consideration of corona discharge in relation to operational dispatch control of power system mode 500 kV

Abstract

Introduction. The article presents the elements and the results of applying the methodology developed by the authors which is intended to determine the parameters of unobservable nodes of the power system. The shortage of a new type of electrical measuring instruments - phasor measurement unit (PMU) - determines a need of the development of an algorithm for computing the electrical parameters of unobservable nodes of the power system, i.e. nodes not equipped with PMU.Goal - using the example of an overhead power transmission line (LEP) with a length of 286 km, to conduct a study of the effect of corona discharge under various weather conditions characteristic of a number of Russian regions on changes in the operating parameters of power lines: voltage losses, phase angle of current and voltage.Materials and methods. Calculations were carried out using two models: with a dynamic corona depending on meteorological conditions (Levitov’s method), and with a static discharge determined by average annual losses.Results and discussion. It was found out that the influence of the dynamic corona on the difference between voltage losses and the expected result (i.e., obtained by means of the traditional model with a static corona) is negligible (no more than 200 V), while the effect on the phase shifts of current and voltage is much more significant and as a rule exceeds the limits of the PMU errors. In the study is noted that the current phase shift is much more sensible to weather changes than other parameters.Conclusion. The authors recommend taking into account effect of a meteorologically dependent corona in the future developments in order to avoid accumulated error (if there are number of power lines equipped with only a few PMU at the beginning or end). It is also important to take into account dynamic corona discharge for system operated by automatic algorithms in order to avoid occurrence of incorrect interpretations of phase shifts caused by weather changes as potentially dangerous electrical processes caused by regime processes of a possible transition of the system to a pre-emergency state.

Keywords

• phasor measurement unit
• operational dispatch control
• corona discharge
• weather conditions
• observability