Resonant current limiting system and control method

Abstract

The invention provides a resonant type current limiting system and a control method thereof. The resonant type current limiting system comprises three phase branches. Every phase branch is composed of a transformer, a PWM (pulse-width modulation) rectification module, a cascade inversion module and a three-phase (temperature coefficient of resistance) branch with (metal oxide varistor) protection, wherein the primary stage of the transformer is connected with a power grid; the PWM rectification module is connected with the secondary stage of the transformer for rectifying the output voltage of the transformer; the input end of the cascade inversion module is connected with the output end of the PWM rectification module; an LCL filter is connected between the output end of the cascade inversion module and a non-linear load, and the output filter is used for filtering the voltage output by the cascade inversion module and outputting the filtered voltage to the non-linear load; the three-phase TCR branch with the MOV protection is connected between the filtering inductor and the filtering capacitor at the inverter outlet of the LCL output filter. The resonant type current limiting system and the control method thereof can provide a multifunctional current limiter to stabilize load voltage, limit fault current and achieve resonant current management during a fault period, thereby enhancing safety of the power grid.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a resonant current limiting system and a control method. Background technique [0002] Electric energy is a basic energy widely used in industry and people's daily life. In recent years, with the rapid development of my country's industrialization, the use of variable speed drives and power electronic equipment in the industry has increased a lot, and the use of power capacitors in power systems has increased, making power quality and harmonic issues more and more concerned. Non-linear and impact loads not only cause voltage fluctuations, reactive power increases, and three-phase imbalances, but also inject a large number of harmonics into the grid, which brings additional burdens to the grid and seriously affects the power supply quality of the power system. . On the one hand, due to poor regulation of reactive power compensation, the grid voltage is too high or too ...

AI Technical Summary

Problems solved by technology

However, the filtering effect of the LC filter is usually greatly affected by the impedance parameters of the grid; while the LCL filter topology is relatively complex, but the filtering effect is very significant.

Images