Research On Four-Quadrant Current Source Converter Based On Thyristor Control Device

The high-power converter used in the field of transmission is different from the energy storage element.It is usually divided into voltage and current source converter.The voltage source converter has been widely used in engineering.The conversion device based on the half-controlled device satisfies the high voltage High-power demand;the traditional current source converter due to the existence of the exchange side of the energy storage inductor limits its development.With the continuous development of science and technology,based on the traditional twelve pulse rectifier circuit superimposed DC injection unit topology can effectively eliminate the harmonic,while the flexibility to control the active and reactive power,to overcome the thyristorbased conversion device can not achieve full range of power control.It can be run in the rectifier,inverter,STATCOM mode,and realize the four-quadrant operation that it has wide application value in the field of HVDC transmission and flexible AC transmission.Based on the topology of current source converter,the DC-side stacking circuit is adopted to study the realization of four-quadrant operation method.Firstly,according to the traditional 12-pulse rectification topology,the working principle and topology of the four-quadrant current source system are clarified by using the harmonic compensation method,which provides the theoretical basis for the hardware circuit design of the system.Of the distribution branch switch combination to generate multi-step level of the quasi-triangular wave,the use of double-winding inductor current sharing to ensure the continuity of the converter current.The basic operation characteristics of the fourquadrant current source converter system are studied by simulation,and the current flow problem in STATCOM mode is improved.The influence of three kinds of injection circuit driving strategies on the current sharing effect is compared,and the control method of state traversal has the same effect.Finally,the specific design scheme of the system hardware circuit is determined,the power control strategy under the typical working mode,the design and selection of the key components and the design of the transformer are selected.The DSP is used as the controller to realize the hardware circuit and the control cabinet.Four quadrant operation function,while comparing the four quadrant current source converter used in rectification,inverter,STATCOM mode of operating characteristics.