Abstract
This paper developed a novel single-phase reactive current detection algorithm based on fast orthogonal signal generator (OSG) and enhanced moving average filter (MAF), overcoming the limitation of conventional schemes in detection speed, computation burden and noise/harmonic immunity. A fast and accurate OSG scheme is introduced first, which can remarkably improve the precision and response speed of the developed detection scheme. In d-q frame, the enhanced MAF is developed and its optimal design principle is also presented, which can sufficiently eliminate the noise and harmonics while achieve the possible shortest response time, particularly in the case of selective harmonics cancellation. Finally, high-performance single-phase STATCOM control is realized utilizing the proposed method. Experiments reveal that the proposed detection scheme exhibits fast speed, high precision as well as noise/harmonics immunity, providing satisfactory control performances.
Highlights
Reactive power transmission in power grids increases energy loss and leads to low network efficiency, reactive power needs to be compensated locally
The introduced orthogonal signal generator (OSG) scheme does not amplify interfering signals, and it maintains high precision of generated orthogonal signal on the condition that computational burden is not increased significantly
Experiments based on a signal generator and a single-phase cascaded STATCOM were carried out to verify the proposed reactive current detection algorithm based on the developed enhanced moving average filter (MAF)
Summary
Reactive power transmission in power grids increases energy loss and leads to low network efficiency, reactive power needs to be compensated locally. Fryze methods are based on the calculation of average power and require reactive current integral in one period; these methods exhibit weak real-time performance [7,8,9,10,11]. Energies 2018, 11, 733 intuitively obtained and must be acquired by some other methods [10,11,12] These algorithms need two FFT processes, causing long detection time and weak real-time feature. The application in single-phase grid requires the construction of virtual phase (a-b-c) signals or virtual orthogonal (α-β) signals, in which the detected load current serves as one signal and the other signals require proper generation algorithms. The cascaded MAF (CMAF) blocks with different time delays can eliminate several harmonics Such CMAF inevitably cause the long-time delay, failing to meet the fast response requirement for STATCOM.
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