Study on constraints for harmonic source determination using active power direction

Xu, Fangwei; Hong-geng, Yang; Zhao, Jinshuai; Wang, Zhiqi; Liu, Yamei

doi:10.1109/tpwrd.2018.2828034

Cited by 32 publications

(32 citation statements)

References 17 publications

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“…en, we obtain the following function l(θ) based on the principle of Jensen's inequality: 17, the maximum value of the lower bound function can be obtained, so that equation (17) can gradually approach the optimal solution or obtain the local optimal solution as follows:…”

Section: Utility Harmonic Impedance Estimationmentioning

confidence: 99%

“…At present, the mainstream methods for estimating the utility harmonic impedance are noninvasive, which mainly include the linear regression method [8][9][10][11][12][13], fluctuation quantity (FQ) method [14,15], independent random vector (IRV) method [16], and independent component analysis (ICA) method [17][18][19][20][21][22]. e linear regression method uses linear regression to calculate Norton equivalent circuit equation coefficient and obtain the harmonic impedance.…”

Section: Introductionmentioning

confidence: 99%

“…For instance, the harmonic sources caused by renewable energy and power electronic equipment in power grid widely distribute, the harmonic sources among power electronic equipments interact, and harmonics amplify for transmission lines and cables. us, it is obviously unreasonable that the background harmonic is assumed to be very small and stable [17]. Besides, filters or reactive compensation capacitors are usually installed on the customer side, which may cause the harmonic impedances of both sides to be approximately equivalent.…”

Section: Introductionmentioning

confidence: 99%

“…Besides, filters or reactive compensation capacitors are usually installed on the customer side, which may cause the harmonic impedances of both sides to be approximately equivalent. As for, the independence hypothesis of the harmonic sources of both sides is much idealized, and many researchers have pointed out that the assumption may not meet the practice [4,5,17,20,22].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A Harmonic Impedance Estimation Method Based on the Cauchy Mixed Model

Tang

et al. 2020

Mathematical Problems in Engineering

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In this paper, a new method without any tradition assumption to estimate the utility harmonic impedance of a point of common coupling (PCC) is proposed. But, the existing estimation methods usually are built on some assumptions, such as, the background harmonic is stable and small, the harmonic impedance of the customer side is much larger than that of utility side, and the harmonic sources of both sides are independent. However these assumptions are unpractical to modern power grid, which causes very wrong estimation. The proposed method first uses a Cauchy Mixed Model (CMM) to express the Norton equivalent circuit of the PCC because we find that the CMM can right fit the statistical distribution of the measured harmonic data for any PCC, by testing and verifying massive measured harmonic data. Also, the parameters of the CMM are determined by the expectation maximization algorithm (EM), and then the utility harmonic impedance is estimated by means of the CMM’s parameters. Compared to the existing methods, the main advantages of our method are as follows: it can obtain the accurate estimation results, but it is no longer dependent of any assumption and is only related to the measured data distribution. Finally, the effectiveness of the proposed method is verified by simulation and field cases.

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Section: Utility Harmonic Impedance Estimationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Harmonic Impedance Estimation Method Based on the Cauchy Mixed Model

Tang

et al. 2020

Mathematical Problems in Engineering

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“…Harmonic sources in a power system become complex and diverse as more nonlinear customers connected to the power grid [ 1 , 2 ]. For a bus with serious harmonic distortion, evaluating the contribution of each customer is essential to identify the dominant harmonic source and to design the effective scheme for harmonic pollution mitigation [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Harmonic Contributions for Multi Harmonic Sources System Based on Mixed Entropy Screening and an Improved Independent Component Analysis Method

Zhao

Hong-geng

et al. 2020

Entropy

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Evaluating the harmonic contributions of each nonlinear customer is important for harmonic mitigation in a power system with diverse and complex harmonic sources. The existing evaluation methods have two shortcomings: (1) the calculation accuracy is easily affected by background harmonics fluctuation; and (2) they rely on Global Positioning System (GPS) measurements, which is not economic when widely applied. In this paper, based on the properties of asynchronous measurements, we propose a model for evaluating harmonic contributions without GPS technology. In addition, based on the Gaussianity of the measured harmonic data, a mixed entropy screening mechanism is proposed to assess the fluctuation degree of the background harmonics for each data segment. Only the segments with relatively stable background harmonics are chosen for calculation, which reduces the impacts of the background harmonics in a certain degree. Additionally, complex independent component analysis, as a potential method to this field, is improved in this paper. During the calculation process, the sparseness of the mixed matrix in this method is used to reduce the optimization dimension and enhance the evaluation accuracy. The validity and the effectiveness of the proposed methods are verified through simulations and field case studies.

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