Abstract
Different kinds of power quality can be sensed in a smart substation. Power quality sensing and analysis are basic functions of a smart substation for situation awareness. The uncertainty principle, which states that the time uncertainty and frequency uncertainty cannot be minimized simultaneously, is a bottleneck problem that undermines the faithfulness of sensing and confines the accuracy of analysis. This paper studies the influence of the uncertainty principle on the power quality monitoring issue in detail and solves the problem by ideal atomic decomposition (IAD). The new method employs a pair of time and frequency bases where the power quality waveform is sensed. Then, both time uncertainty and frequency uncertainty can be minimized simultaneously. The sensing process is realized by orthogonal matching pursuit (OMP). By simulated and field power quality tests with comparisons of developed methods, the new method can give faithful sensing and accurate analysis for various power qualities, and is validated as an effective power quality monitoring method in smart substations.
Highlights
Power substations play a key role in power transmission and distribution
The paper is organized as follows: Section 2 illustrates the influence of the uncertainty principle on Power quality (PQ) sensing and analysis; Section 3 proposes the ideal atomic decomposition (IAD) to obtain both accurate time and frequency features of the PQ; Section 4 shows the performance of the new method by simulated PQ tests; Section 5 gives cases of PQ sensing and analysis in a smart substation; Section 6 summarizes the whole work
Supposing the quantization number of the analog-to-digital converter (ADC) is certain, the uncertainty in PQ sensing includes time uncertainty, which is controlled by sampling frequency (Fs ), and frequency uncertainty (u f ), which is controlled by sampling time (Ts )
Summary
Power substations play a key role in power transmission and distribution. A smart substation is typically implemented with a sophisticated combination of smart primary high-voltage equipment and hierarchically networked secondary devices. Based on the IEC 61850 communication protocol, the functionalities, such as the information sharing and interoperability among smart electric equipment, are realized in smart substations. They are regarded as the basis for the development of the smart grid and represents the future development trend of substation technologies [1]. PQ sensing and analysis cannot only be for PQ evaluation and for smart grid situation awareness. The main challenges of PQ sensing and analysis in the smart substation are: 2. It is unknown how many kinds of PQ can be sensed.
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