Analysis of Influence of Frequency Converters with Active Rectifiers on the Power Quality in Internal Power Supply Systems of Industrial Enterprises

2018 ◽  
Author(s):  
A.A. Nikolaev ◽  
I.G. Gilemov ◽  
A.S. Denisevich
Keyword(s):  
Power Quality ◽  
Power Supply ◽  
Frequency Converters ◽  
Industrial Enterprises ◽  
Supply Systems ◽  
Active Rectifiers

scholarly journals Power quality in power supply systems of mining and processing enterprises in Russia

2021 ◽  
Vol 25 (3) ◽  
pp. 356-368
Author(s):  
V. I. Panteleev ◽  
I. S. Kuzmin ◽  
A. A. Zavalov ◽  
A. V. Tikhonov ◽  
E. V. Umetskaia
Keyword(s):  
Power Quality ◽  
Power Supply ◽  
Electrical Power ◽  
Load Factor ◽  
Electric Motors ◽  
Higher Harmonics ◽  
Frequency Converters ◽  
Receiver System ◽  
Thyristor Converters ◽  
Supply Systems

This paper investigates the effect of the load factor of frequency converters and thyristor converters on electrical power quality. Recommendations for reducing the influence of higher harmonics and switching overvoltages on the characteristics of electrical power are provided. Higher harmonics were measured by a PKK57 complex device for controlling electrical parameters and a digital oscilloscope of the Tektronix TDS 2024V type. Impulse switching overvoltages were recorded by an active resistance divider of the DNEK-10 type and the above-mentioned oscilloscope. The obtained data were processed by the Loginom 6.4 software and the methods of mathematical statistics. The lower threshold level of the load factor of frequency converters and thyristor converters was set equal to 0.8, at which the sinusoidal distortion of voltage curves correspond to the RF standard of electrical power quality. The suppression degree of higher harmonics from the 5th to 17th frequency by power transformers with a capacity of 250–6,300 kV. A ranged from 95 to 45%. The use of the ‘transformer–converter–electric receiver’ system as applied to the power supply systems of mining and processing enterprises was substantiated. It was shown that electric motors with a capacity of up to 2,500 kW inclusively require protection against switching overvoltages. Conventional RC-absorbers based on RC-circuits connected to the terminals of electric motors are shown to be highly efficient for protecting electric motors against switching overvoltages. Thus, the quality of electrical power in power supply systems of mining and processing enterprises in Russia can be ensured by frequency converters and thyristor converters with a load factor of 0.8 or greater. Provided that the transformer capacity does not exceed 1,000 kV. A, a more efficient and less expensive ‘transformer–converter–electrical receiver’ system is recommended. Effective protection of electric motors of up to 2,500 kW inclusive can be provided using the proposed conventional RC absorber, which maintains the overvoltage rate at a level not exceeding 1.7.

scholarly journals Calculation of the economy of electric energy in industrial electrical supply systems

2020 ◽  
Vol 22 (2) ◽  
pp. 65-74
Author(s):  
E. I. Gracheva ◽  
A. N. Gorlov ◽  
Z. M. Shakurova
Keyword(s):  
Power Supply ◽  
Energy Savings ◽  
Reactive Power ◽  
Electric Energy ◽  
Electrical Equipment ◽  
Total Power ◽  
Load Factor ◽  
Advantages And Disadvantages ◽  
Industrial Enterprises ◽  
Supply Systems

The article examines the main features of the layout of electrical equipment for shop networks of internal power supply with the definition of indicators for a group of shop customers connected to a single power center, affecting the choice of the structure of schemes for shop network sites. The parameters characterizing the circuit topology are revealed. A study is presented of the influence of the load factor of workshop transformers on their reactive power factor, it is proved by calculation by technical and economic criteria the feasibility of replacing a workshop transformer with two with a lower total power. The calculation of energy savings in the in-plant power supply systems. The type of dependences tgφ of transformers ТМ and ТСЗ with various rated powers in the function of loading transformers is established. The most significant factors of the growth of idle power losses during operation are presented. With determination of losses of active and reactive power and electricity in transformers and losses of active power in a high voltage distribution network A feasibility study was carried out on the options for internal power supply schemes with two transformers of lower power installed instead of one, and the feasibility of such a replacement to increase the efficiency of the equipment was proved and the estimated payback period for the investment capital was determined. A comparative analysis of the studied power supply schemes of industrial enterprises with the identification of their advantages and disadvantages.

scholarly journals Improving of operation stability of frequency converters with active rectifiers in electric steel-making complex electrical equipment switching

Vestnik IGEU ◽  
2019 ◽  
pp. 48-58
Author(s):  
A.A. Nikolaev ◽  
A.S. Denisevich ◽  
V.S. Ivekeev
Keyword(s):  
Control System ◽  
Power Supply ◽  
Electric Arc ◽  
Voltage Sags ◽  
Parallel Operation ◽  
Frequency Converters ◽  
Active Rectifier ◽  
Arc Furnaces ◽  
Operation Stability ◽  
Active Rectifiers

Frequency converters with active rectifiers (FC-AR) are now used in rolling mill electric drives. Modern control systems of ARs are not adapted to voltage sags in power supply systems, which leads to converter tripping. The known methods of ensuring AR operation stability, such as kinetic buffering, correction signals based on negative sequence voltage and others, do not eliminate these emergency trips. As an additional measure the paper proposes the method of voltage sag compensation by using static var compensators (SVC) of electric arc furnaces (EAF) for parallel operation of frequency converters with active rectifiers and electric arc furnaces. However, it remains unknown how disturbances (such as overvoltages of switching of SVC harmonic filters (HF) and voltage sags during furnace transformer switching) affect operation stability of frequency converters with active rectifiers. All this makes it necessary to study the effect of these processes on the operation conditions of FC-AR and to improve the active rectifier control system. The authors used experimental arrays of instantaneous values of voltages and currents of the real-life complex «EAF-SVC» («Electric Arc Furnace – Statistic VAR Compensator») in this study. They also applied mathematical models of FC-AR with different PWM algorithms realized in Matlab-Simulink software. The main assumption of the model consists in using equivalent current sources modelling the operation of autonomous voltage invertors. An improved control system of AR has been developed. The main feature that distinguishes it from the known systems is the fact that it ensures operation stability during SVC harmonic filter and EAF transformer switching by using a signal conditioning unit for setting the active rectifier reactive current component as a function of power supply and AR input voltage difference. Implementation of the improved AR control system improves FC-AR stability during parallel operation with EAFs through reactive power consumption of the supply system. As a result, it reduces the amplitude of inrush current and voltage deviations in the DC-link of the FC-AR to the values lower than the setpoints of the AR protection system.

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