Анастасия Литвинова

The Republic of South Africa still cannot recover from the ramifications of the 2008 economic crisis. The country has lost a million jobs created over the previous four years, while South Africa’s GDP shrank from 296.87 billion dollars to 294.9 billion dollars in 2011-2016. The main blow fell upon the mining industry.

The PRC, as before, plans to send a representative delegation to the City on the Neva to participate in the youth forum, which will be held as part of the BRICS summit in July. And what shall we do about the quarantine?

The balance of electricity consumption a significant part is occupied by the production of compressed air at the mining enterprises. Many compressor stations of enterprises are equipped with automated parameter management systems that allow reliable, uninterrupted and safe operation of the compressor facilities. But the majority of automation systems at compressor stations do not perform the function of monitoring the energy efficiency indicators of the operation of a compressor station.

The paper addresses issues of using the active rectifier in partially loaded variable frequency drive as active filter in the conditions of non-sinusoidal current and voltage disturbances caused by the presence of high-power nonlinear load in the grid. The topology of transformless three-level converter for 6-10 kV suitable for proposed solution has been presented and its mathematical model has been de-rived. Based on the model, the direct power control algorithm with ability to compensate non-linear currents has been designed. The investigation of active rectifier efficiency was performed depending on the relation between linear and non-linear load currents of the grid node, as well as on active power load of the active rectifier. Efficiency analysis was based on the developed computer model of the grid node with connected non-linear load simultaneously with the variable frequency drive with active rectifier.