Chained SVG module voltage-equalizing control method and circuit

Abstract

The invention discloses a chained SVG module voltage-equalizing control method and circuit. Each phase of power module in a three-phase power module comprises a plurality of H-bridge modules, a central controller, a plurality of sampling controllers and a plurality of voltage-equalizing branch circuits. A direct current side capacitor of each H-bridge module is connected with one voltage-equalizing branch circuit in parallel, a direct current bus of each H-bridge module is connected with one sampling controller, a data output end of each sampling controller is connected with an input end of the central controller, a control input end is connected with an output end of the central controller, and a control output end is connected with a control input end of each voltage-equalizing branch circuit. The central controller is used for collecting voltage values of the direct current buses of all the H-bridge modules in a link through the sampling controllers, carrying out averaging operation and voltage-equalizing control operation on the direct current voltage values, and emitting control pulses of the H-bridge modules through optical fibers. The chained SVG module voltage-equalizing control method can ensure that the H-bridge modules are completely uniform, the process is simple, and mass production is facilitated. The voltage-equalizing effect is irrelevant to the strength of current, so a promising result can be achieved when the current is quite weak.

Description

technical field [0001] The invention relates to a voltage control circuit, in particular to a chained SVG module voltage equalization control method and circuit. Background technique [0002] With the development of power electronics technology, static synchronous compensators (SVG) based on high-power turn-off devices (IGBT, IGCT) have developed rapidly, and direct-mounted devices with different voltage levels such as 6KV, 10KV, and 35KV have been realized in factories Industrialized production, SVG can quickly compensate the reactive power or harmonic current of the load or the power grid, improve the power factor of the power grid and reduce the harmonic content, and gradually expand the market share to replace a large number of old-fashioned reactive power compensation devices, such as SVC, fixed switching capacitors etc. [0003] The main circuit structure of medium and high voltage SVG mainly includes multi-level structures such as multiplexing and chaining. Among the...

AI Technical Summary

Problems solved by technology

[0005] Chinese patents 03142679.4 and 200910238798.2 both proposed a circuit and method for DC-side voltage equalization control of chained SVG power modules. They enable energy exchange between H-bridge cascaded power modules through additional external devices, thereby realizing balanced control of capacitor voltages , but their additional external circuits are very complicated, and at the same time, the cascaded power modules are indirectly connected together through transformers, which cannot achieve true electrical insulation, which puts forward higher requirements on the voltage isolation capabilities of additional equipment, especially transformers

[0006] Chinese patent 200610113547.8 proposes a software control method for DC-side voltage equalization of chained SVG power modules. This method fine-tunes the switching signal of the power module based on the DC voltage, thereby controlling the DC-side voltage by linking the current to charge and discharge the power module. Balanced control, this method cannot achieve the expected voltage equalization effect when the link current is small

Images