Abstract
With the increasing proportion of various unbalanced loads in the power grid, power quality is seriously challenged. It is of great significance to effectively detect, analyze, and evaluate the power quality problems. First, this paper introduces the current situation of power quality (PQ) disturbance detection methods. It summarizes that the current PQ disturbance detection methods include Wavelet Transform (WT), Hilbert–Huang Transform (HHT), and Ensemble Empirical Mode Decomposition (EEMD). EEMD has a better detection accuracy, but its running time is longer. Therefore, to reduce the running time of the EEMD algorithm, this paper proposed two improvements: increasing the screening threshold and selecting piecewise cubic Hermite interpolation polynomial fitting. At the same time, the mathematical models of transient power quality disturbance and harmonic were established for comparative verification. The experimental results showed that the improved Ensemble Empirical Mode Decomposition (IEEMD) algorithm greatly reduced the running time of the algorithm on the premise of ensuring the detection accuracy. Hence, the improvement of this paper is of great significance for the industrial application of the EEMD algorithm.
Highlights
In the modern power system, power quality has become very unstable due to the large numbers of nonlinear loads and generators in the grid
By comparing and analyzing the data in the table, we found that the running time difference between the improved Ensemble Empirical Mode Decomposition (EEMD) algorithm and the Wavelet Transform (WT) method was about 0.3s
This paper mainly focuses on the problem that the EEMD algorithm is applied to power quality disturbance detections when the running time is too long
Summary
In the modern power system, power quality has become very unstable due to the large numbers of nonlinear loads and generators in the grid. Power electronic-based systems such as adjustable speed drives, power supplies for IT-equipment, high-efficiency lighting, and inverters in systems generating electricity from distributed renewable energy sources are sources of disturbances [1]. The power quality (PQ) affects the operation of the power system, but it is closely related to the development of the national economy. High-quality power can effectively make all parts of the power system to run efficiently and smoothly, allowing the national economy to develop at high speed. The cost of the power industry will increase significantly and may lead to the deterioration of the stability of the power system, which will seriously affect the national economy.
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