Abstract
The necessity and topicality of the problem of improving the efficiency of compensation for power consuming asymmetrical equipment negative influence on the low-voltage mains have been demonstrated. That is why the ways of improvement of the compensation system have been offered on the basis of the analysis of the processes of compensation for currents non-active components in a three-phase power supply system under the conditions of supply voltage unbalance. The analysis was performed in an analytical form in the frequency domain. An instantaneous power cross-vector theory was used to generate active and reactive power instantaneous components and also to determine compensation currents in the analyzed power supply system. Improvement of the method consists in exclusion of voltage asymmetrical components, caused by the mains distortions, from the algorithm of generation of compensation currents. It was realized with the use of the designed blocks of separation and balancing of the supply mains voltage signals. The latter improved the efficiency of operation of power supply systems and the speed of operation of the compensation system. The significance of the presented paper consists in the fact that the offered method provides correct operation of the compensation system under the conditions of unbalance of the supply mains voltages. This makes it possible to improve power indices of the power supply system, to reduce the value of reactive power, voltage drop at the mains resistances, unbalance coefficient and the coefficient of distortion of currents sinusoidality and supply mains voltages. In the future, the presented method will be applied to compensation for currents non-active components in industrial power supply systems to which nonlinear and asymmetric equipment, characterized by a sharply changed operation modes, is connected.
Highlights
Nowadays the share of power-consuming loads of low-voltage power supply systems defined by nonlinearity of their characteristics and unbalance of parameters in phases has greatly increased
According to the papers [1, 2], only the basic harmonic component being of a sinusoidal form and existing in the phase with the mains voltage is understood as active current
It is known that calculations of compensation currents for Active power filters (APF) in three- and four-wire power supply systems are done on the basis of the known theories of instantaneous power (IP) [7, 10]: p-q [4], cross-vector [5] and p-q-r ones [5, 6]
Summary
Nowadays the share of power-consuming loads of low-voltage power supply systems defined by nonlinearity of their characteristics and unbalance of parameters in phases has greatly increased. Such types of loads include welding apparatuses, controlled electric drives, electric-chemical plants, etc. Operation of such equipment results in occurrence of higher harmonics in currents and voltages and in unbalance of voltages and currents in the power supply system. The present economic situation, in particular, the rise of the cost of electric power for industrial enterprises, causes the necessity and topicality of the problem of improvement of the efficiency of compensation for nonlinear and asymmetric power-consuming equipment negative influence on low-voltage supply mains
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