Method for detecting harmonic current of power grid current

Abstract

The invention provides a method for detecting harmonic current of power grid current. The method for detecting the harmonic current of the power grid current relates to a harmonic current detecting part, a harmonic current decomposing part, a harmonic current scale factor calculating part and a harmonic wave content calculating part. The method for detecting the harmonic current of the power grid current is based on the instantaneous reactive power theory and combined with Fourier transform, can rapidly and accurately calculate the harmonic current each time, the harmonic current at a certain time or certain times can be conveniently compensated according to calculated harmonic current values each time, the difficulty for implementing the method for detecting the harmonic current of the power grid current is reduced, the harmonic current can be rapidly detected, therefore, stability and reliability of an active power filter governing device are effectively improved, and then cost of the active power filter governing device is effectively lowered, market competition advantages of the active power filter governing device using the technology is beneficially improved, and power quality of a clean power grid is further beneficially improved.

Description

technical field [0001] The invention belongs to the field of power electronics and relates to a harmonic current detection method, in particular to a harmonic current detection method of grid current. Background technique [0002] With the development of frequency conversion technology, power electronic equipment is widely used in various fields, which brings great convenience to people's life. At the same time, it brings great pollution to the power grid. The ideal power grid voltage should be a single The sine wave with fixed frequency can have a small deviation according to the corresponding national standard. The high-order harmonic current and harmonic voltage generated by the frequency conversion equipment have a great impact on the grid voltage, and in serious cases, it will endanger the normal operation of the equipment. Operation, even the stable operation of the entire power grid, for this reason, filtering equipment came into being. [0003] Passive filters and a...

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Problems solved by technology

[0002] With the development of frequency conversion technology, power electronic equipment is widely used in various fields, which brings great convenience to people's life. At the same time, it brings great pollution to the power grid. The ideal power grid voltage should be a single The sine wave with fixed frequency can have a small deviation according to the corresponding national standard. The high-order harmonic current and harmonic voltage generated by the frequency conversion equipment have a great impact on the grid voltage, and in serious cases, it will endanger the normal operation of the equipment. operation, and even the stable operation of the entire power grid, for this reason, filtering equipment came into being

[0003] Passive filters and active power filters have become the main equipment for harmonic control in power grids. Early passive filters were widely used due to their advantages of simple structure, low cost, and large capacity, but their filtering effects were poor and resonance easily occurred, resulting in It is gradually eliminated; with the development of power electronics technology, the cost of IGBTs mainly used in active power filters is reduced, resulting in active power filters will be widely used, and then replace passive power filters, active power filters It has the advantages of compensating various harmonics, suppressing flicker, automatic tracking, fast compensation, etc., and has received great attention from people.

[0004] One of the main technologies in the active power filter is harmonic current detection, but the harmonic current detection algorithm of the active power filter is generally based on the Fourier transform, the transformation is complex, and the fast tracking effect is poor. According to the "People's Republic of China The technical requirements in the machinery industry standard JB / T11067-2011 require that the response time of the compensation equipment is less than or equal to 40ms, and some industries even require the response time to be less than 10ms. To meet these requirements for the treatment equipment based on Fourier transform, the cost will increase a lot , and some technicians have proposed detection algorithms based on instantaneous reactive power theory, but most of them are theoretical studies, and it is difficult to implement them.

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