LCL (Less Container Load) filter with serially-connected splitting capacitor and damping resistor and design method of LCL filter

Abstract

The invention provides an LCL (Less Container Load) filter with serially-connected splitting capacitor and damping resistor and a design method of the LCL filter which are applied to the technical field of wind power, wherein a grid side electric reactor and a grid-connected inverter side electric reactor are sequentially connected in series, and a first three-phase filter capacitor and a damping resistor are connected in series to a serial-connection node of the two electric reactors; a second three-phase filter capacitor is directly connected to the serial-connection node of the two electric reactors; a three-phase network source is connected to a Lg terminal of the grid side electric reactor; and a three-phase alternating current side of a wholly-controlled rectifier bridge of a grid-connected inverter is connected to terminals of the electric reactors. By using the LCL filter, the stability problem of a voltage type controllable inverter of the LCL filter is solved, the power consumption on the damping resistor can be effectively reduced, the overall efficiency of a grid-connected inverter system can be increased, and thus, the system heat radiation design pressure is relieved.

Description

technical field [0001] The invention relates to the technical field of wind power grid-connected converters, in particular to an LCL filter using a split capacitor connected in series with a damping resistor and a design method thereof. Background technique [0002] The three-phase voltage source type grid-connected inverter has the advantages of low harmonic content of output current, power factor adjustment and bidirectional energy flow, small size and light weight, so it is widely used in active filtering, traditional electric power and renewable energy such as solar energy and wind energy. It has been widely used in grid-connected power generation systems and other fields. [0003] The converter side of the three-phase voltage source grid-connected inverter controlled by PWM modulation technology will generate switching frequency and harmonic frequency current that is an integer multiple of the switching frequency. The harmonic current will pollute the grid voltage and s...

AI Technical Summary

Problems solved by technology

[0008] The traditional passive damping control is to connect resistors in series with the filter capacitor branch of the LCL filter, so as to realize the resonance damping of the LCL filter, but the biggest defect of passive damping control is that the series damping resistor needs to consume a large amount of active power. It brings certain challenges to the heat dissipation design of the system, so for passive damping control, how to reduce the power loss of the damping resistor is a difficult problem

Images