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Protection from the high impedance fault (HIF) has been one of the biggest challenges in the power distribution network. HIF typically occurs when the conductors in distribution network break and touch the ground surface; or lean and touch a tree branch. This fault, with current magnitude close to the load current level, is not detectable by over-current relays. This paper aims to review the literature related to the HIF phenomenon. In this work, the HIF detection techniques are categorized, evaluated, and compared with one another. Furthermore, the existing HIF models and HIF location techniques are reviewed. Finally, the shortcoming of the existing perspective toward the HIF phenomenon and the possible road to the future for HIF detection is discussed. [ABSTRACT FROM AUTHOR]

In this article, we introduce a fractional order of rational Bessel functions collocation method (FRBC) for solving the Thomas-Fermi equation. The problem is defined in the semi-infinite domain and has a singularity at x = 0 and its boundary condition occurs at infinity. We solve the problem on the semi-infinite domain without any domain truncation or transformation of the domain of the problem to a finite domain. This approach at first, obtains a sequence of linear differential equations by using the quasilinearization method (QLM), then at each iteration the equation is solves by FRBC method. To illustrate the reliability of this work, we compare the numerical results of the present method with some well-known results, to show that the new method is accurate, efficient and applicable. [ABSTRACT FROM AUTHOR]

This paper studies sub-synchronous resonance (SSR) in doubly-fed induction generator (DFIG)-based wind farms. The paper first briefly reviews the main types of the SSR that may occur in DFIG wind farms, namely: (1) induction generator effect (SSIGE), (2) torsional interactions (SSTI), and (3) control interactions (SSCI). It is shown that the power system is highly unstable due to the SSR mode. Therefore, a supplementary SSR damping controller (SSRDC) is designed for the grid-side converter (GSC) controller of the DFIG. The SSRDC is designed using an observer-based controller tuned through an optimal quadratic technique. Model reduction is applied to the full model of the studied power system in order to obtain a lower order model to make the SSRDC design simpler and more practical. The IEEE first benchmark model, modified to include a 100 MW DFIG-based wind farm, is employed as a case study. In this work, MATLAB/SIMULINK is used for eigenvalue analysis and PSCAD/EMTDC for time-domain simulations, respectively. [ABSTRACT FROM AUTHOR]

A new high-impedance fault (HIF) detection method using time-frequency analysis for feature extraction is proposed. A pattern classifier is trained whose feature set consists of current waveform energy and normalized joint time–frequency moments. The proposed method shows high efficacy in all of the detection criteria defined in this paper. The method is verified using real-world data, acquired from HIF tests on three different materials (concrete, grass, and tree branch) and under two different conditions (wet and dry). Several nonfault events, which often confuse HIF detection systems, were simulated, such as capacitor switching, transformer inrush current, nonlinear loads, and power-electronics sources. A new set of criteria for fault detection is proposed. Using these criteria, the proposed method is evaluated and its performance is compared with the existing methods. These criteria are accuracy, dependability, security, safety, sensibility, cost, objectivity, completeness, and speed. The proposed method is compared with the existing methods, and it is shown to be more reliable and efficient than its existing counterparts. The effect of choice of the pattern classifier on method efficacy is also investigated. [ABSTRACT FROM AUTHOR]

This paper first presents a step‐by‐step tutorial on modal analysis of a doubly‐fed induction generator (DFIG)‐based series compensated wind farm. The model of the system includes a wind turbine aerodynamics, a sixth‐order order induction generator, a second‐order two‐mass shaft system, a fourth‐order order series compensated transmission line, an eighth‐order rotor‐side converter (RSC) and grid‐side converter (GSC) controllers, and a first‐order DC‐link model. Then, using modal analysis and time‐domain simulations, it is shown that a fixed‐series compensated DFIG is highly unstable due to the sub‐synchronous resonance (SSR) mode. In order to damp the SSR mode, the wind farm is interfaced with the gate‐controlled series capacitor (GCSC) ‐ which is a new series flexible AC transmission system (FACTS) device. A SSR damping controller (SSRDC) is designed for the GCSC using residue‐based analysis and root locus diagrams, and an effective input control signal (ICS) to the SSRDC is identified in order to simultaneously increase damping of both the SSR and super‐synchronous (SupSR) modes. The IEEE first benchmark model on SSR is adapted with an integrated DFIG‐based wind farm to perform studies. Matlab/Simulink is used as a tool for designing process, and PSCAD/EMTDC is used for time‐domain simulations. [ABSTRACT FROM AUTHOR]

• Impacts of non-periodic are similar to harmonic current but more difficult to mitigate. • Time-frequency distortion index is most suitable for non-periodic loads. • Hybrid time-frequency method provides temporally distributed current reference. • Temporal distribution of compensation increases efficiency and reduces overall cost. • Fuzzy algorithm based on non-periodic characteristics decreases bandwidth requirements. This paper presents a new technique for the compensation of non-periodic load current. The method provides control references for three co-located devices, each corresponding to one moving calculation window and one decomposed part of the compensated current. They are slow compensator with high power rating, large calculation window, and low switching frequency; fast compensator with lower power rating, shorter calculation window, and higher switching frequency; and the reactive compensator which is an ordinary static VAR compensator (SVC). A fuzzy based adaptive window is proposed for the slow compensator to find the optimum window for different load characteristics. The technique is evaluated using real-world data and controller hardware-in-the-loop (HIL) implementation. [ABSTRACT FROM AUTHOR]

IEEE Standard 1459 defines the power components based on the fast Fourier series. However, Fourier series assumes the signal is periodic in nature, and provides erroneous assessment of the power components in the presence of transient signals. Therefore, a new method is proposed for the evaluation of the IEEE Standard 1459 power components based on the time-frequency distribution (TFD) and the cross time-frequency distribution (XTFD) of transient signals. The TFD and XTFD preserve simultaneous time and variable frequency information of transient signals, and estimate the instantaneous power components according to IEEE Standard 1459. Results of computer simulated and real-world power quality disturbance case studies justify the effectiveness of the proposed method for the assessment of instantaneous power components under transient conditions. [ABSTRACT FROM AUTHOR]