Output amplitude-limiting method for three-phase four-wire system type SVG device

Abstract

The invention provides an output amplitude-limiting method for a three-phase four-wire system type SVG device. The method is characterized in that reactive, negative sequence, zero sequence, and sub harmonic amplitude limiting is carried out to realize an effect of capacity distribution of all compensation capacities. Meanwhile, after compensation value superposition, effective value limiting is carried out on a three-phase four-wire instruction, so that the device carries out reactive, negative-sequence, zero-sequence and harmonic compensation on a power grid in a given mode within a capacity value-limiting range. With the provided method, capacity limiting can be carried out on all compensation capacities effectively; effective value limiting for the three-phase four-wire unit including harmonics is realized by using single sampling period data; and the compensation scheme can be modified in real time. Moreover, no over current is caused by the device at any time, so that the safe and stable operation of the device is guaranteed.

Description

technical field [0001] The invention relates to an output limiting method of a three-phase four-wire system SVG device, which belongs to the technical field of power electronic device control. Background technique [0002] The three-phase four-wire system SVG device is more and more widely used in factories and mines, distribution transformer outlets and other occasions because it can effectively compensate reactive power, three-phase unbalance and harmonics in real time without difference. It has played a very good role in reducing loss and improving the quality of three-phase power supply voltage. However, due to the limitations of power switching devices and main circuit devices, the capacity of the compensation device has a certain limit. Since the three-phase unbalanced compensation amount will cause the output of the compensation device to be unbalanced, it may lead to an overload of one or two phases of the device. line output does not exceed the limit. [0003] Th...

AI Technical Summary

Problems solved by technology

Although the cut-off limit is simple to control and consumes less processor resources, the over-current cut-off introduces harmonic commands, causing the device to output unnecessary harmonic currents, causing harmonic pollution

[0004] Publication No. CN104009486 discloses an asymmetrical compensation current limiting method for three-phase three-wire SVG. The current limiting method mentioned in the patent overcomes the problem of truncated current limiting and introducing harmonics, but uses a quarter of the power frequency cycle The sliding window method to calculate the effective value of the command has a certain time lag, and the dynamic performance needs to be improved

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