Purpose. The development of a universal criterion of determining busbar parameters for operating or calculating values of network power factor, as well as defining parameters of reactive power compensation devices for reducing losses and voltage drops in three-phase systems of power networks. Improvement of the method of preliminary voltage drop estimation in these systems of power networks, which allows taking into account the influence of the skin-effect, the proximity-effect, density and frequency of fundamental and higher current harmonics, depending on the design parameters of steel busbars, short-circuit ratio and operating or calculating values of network power factor. Methodology. For preliminary estimation of voltage drop in AC busbars, the analytical expressions were used which allow taking into account the design parameters of busbars, the skin-effect, the proximity-effect, density and frequency of the first and higher current harmonics. The preliminary estimation of the full or partial voltage drop compensation, caused by at action of the higher current harmonics was performed by the method of comparative analysis. Findings. A dimensionless function is proposed for estimation of the behavior of busbar voltage drop and optimal choice of their design parameters, depending on calculating or operating values of network power factor for active-inductive and active-capacitive loads. At the design or modernization stages of the workshop networks, for needed or operating value of the network power factor, the dimensionless function allows estimating the resistance and reactance ratio of busbars for the purpose of minimizing voltage drop from overflows of reactive power in the shop networks. For the active-capacitive loads, the dimensionless function provides a preliminary estimation of the required rated value of power of the reactive power compensation devices to minimize the voltage drop in the busbars of the networks. By the improved technique of selecting the optimal busbar design parameters, with the influence of the skin-effect, proximity, density and frequency of the fundamental and higher current harmonics voltage drop was evaluated in conditions of non-sinusoidal busbar current. Depending on the short-circuit ratio and the current loads, the value of the voltage drop of busbars would increase by 1,73 - 2,51 times. At the maximum allowable current load value of busbars, the full compensation, and particular overcompensation of the voltage drops, caused by the action of higher current harmonics, is performed at lower values of the short-circuit ratio. In this case, the reactive power compensation devices with a smaller related capacity value can be used. At high values of the short-circuit ratio, the current load of busbars must be reduced. Originality. A universal criterion in the form of a dimensionless function was proposed. For the operating or calculating values of network power factor, it allows choosing the optimal design parameters for steel busbars, as well as defining the parameters of reactive power compensation devices for reducing losses and voltage drops in three-phase networks power systems. The method of preliminary voltage drop estimation in AC three-phase networks power systems, which allows taking into account the influence of the skin-effect, the proximity-effect, density and frequency of the first and higher current harmonics, depending on the design parameters of steel busbars, short-circuit ratio and operating or calculating values of the network power factor was improved.

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