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Optimal placement and sizing of shunt capacitors are important issues to improve voltage profile and reduce power losses in distribution networks. In this regard, dealing with stochastic nature of wind farms (WFs), the issue becomes more complex in wind‐integrated radial distribution networks. This study aims at optimal siting and sizing of shunt capacitors considering wind uncertainty. Application of probabilistic approach causes to access more real and extensive information about the network. To do so, Monte Carlo simulation (MCS) is employed to assess stochastic variation of wind farm output. As the salient feature of this research, K‐means‐based data clustering approach is utilised, in which all data‐points of the output power of WFs are bunched into desired clusters to ease the solving of simple MCS. The voltage profile and power losses are analysed to do the optimal siting and sizing of capacitors. In order to assess the effectiveness of the proposed method, results are compared with the simple MCS that proves the efficiency of the proposed method from the viewpoint of computation time. [ABSTRACT FROM AUTHOR]

Technologies such as the integration of distributed generations (DGs) and shunt capacitors (SCs) are key for realising smart distribution systems[AQ ID=Q2]. These technologies may be coordinated together to get better solutions so that distribution systems can achieve optimum performance. This study proposes a long‐term distribution system planning methodology to determine the optimal sizing and siting of SCs and mix of dispatchable and intermittent DGs. More practical formulations are suggested while considering realities of modern distribution systems with reference to the stochastic nature of load demand and power generation among distribution buses on account of diversity, variability and uncertainty. The long‐term costs in the proposed planning model include several techno‐economic and social objectives pertaining to investment, operation and maintenance of these distributed resources and the revenue generated by sale of electricity to customers and the utility grid. The proposed planning model is more practical as it fully considers the system uncertainties and variability in load and power generation which are efficiently handled by introducing deterministic self‐adaptive uncertainty model. The case study on a standard test distribution system being modified by wind turbines, photovoltaic generators and microturbines demonstrates the effectiveness of the proposed methodology. The results of study are investigated and presented. [ABSTRACT FROM AUTHOR]

A two‐layer control method is proposed for voltage and reactive power control in harmonic polluted distribution network with penetration of photovoltaic (PV) systems. Optimal scheduling of load tap changer and shunt capacitors for minimising energy losses and improving the power quality simultaneously are performed using P‐particle swarm optimisation (PSO) optimisation method. Here, the minimising cost of real power losses and improving the power quality criteria have been pursued as the goals of an optimisation problem. Considering load and PVs output forecast, the first‐layer control determines the optimal reactive power and control settings for all mechanical controllers. Hourly errors of load and power forecasts and mechanical control setting of the first layer are used to estimate optimised reactive power of PV in order to achieve maximum voltage regulation, reduce network losses and total harmonic distortion (THD). These data are trained a neural network (NN) to estimate optimised PV reactive power. This NN in the second layer is used to optimise the online reactive power setting based on online PV power. For more practical applications of the proposed method, simulation is carried out in a large distorted 37‐bus distribution system. The algorithm will increase use of renewable energies, reduce voltage fluctuations, THD, and wear and tear of mechanical equipment. [ABSTRACT FROM AUTHOR]

For compensating reactive power, shunt capacitors are often installed in electrical distribution networks. Consequently, in such systems, power loss reduces, voltage profile improves and feeder capacity releases. However, finding optimal size and location of capacitors in distribution networks is a complex combinatorial optimisation problem. In such problem, an objective function which is usually defined based on power losses and capacitor installation costs should be minimised subject to operational limitations. In this study, a newly developed metaheuristic technique, named crow search algorithm (CSA), is proposed for finding the optimal placement of the capacitors in a distribution network. CSA is a population‐based technique inspired by the greedy behaviour of crows in finding better food sources. The main reasons of using CSA are its easy implementation, few parameters to adjust, fast convergence speed and high efficiency. In the case studies, simulated results indicate that the proposed CSA produces more accurate results than the other studied search methods. [ABSTRACT FROM AUTHOR]

Maximum available power (MAP) is an index for analyzing power‐voltage stability in high‐voltage direct current (HVdc) converters. Earlier work on calculating MAP for voltage sourced converters (VSC) was not consistent with the methods used for line commutated converters (LCC). The Thévenin voltage source used in VSC‐HVdc analysis was set to 1.0 pu, but for LCC‐HVdc, it was calculated so as to provide rated conditions at the converter busbar. This study attempts to rationalize the approaches used for VSC‐HVdc and LCC‐HVdc calculations by making them mutually consistent. However, as the VSC can operate at much lower short‐circuit ratio (SCR) than can the LCC, the Thévenin equivalent voltage at low SCRs can be significantly larger than 1.0 pu. This would require an unreasonably large tap changer setting. As an alternative, the paper recommends that for calculating MAP for a VSC, an ac network equivalent be used where some reactive power is locally supplied by shunt capacitors. This renders a Thévenin voltage close to 1.0 pu. This study also considers the impact of the VSC's internal voltage limits on the MAP. The key results are validated using electromagnetic transients simulation. [ABSTRACT FROM AUTHOR]

This study presents a new equivalent circuit modelling methodology for various‐type spiral resonators in printed circuit board environment. The N‐turn spiral resonator can be decomposed into an N Π‐equivalent circuit model, and each Π‐model is comprised of a series inductance, parallel capacitance, two shunt capacitors and the resistances of the conductor and dielectric. Both the inductance and capacitance of the equivalent circuit are calculated by the proposed formulas, which are based on the electromagnetic theory. It has been demonstrated that the proposed equivalent circuit model of the spiral resonator is well matched in S‐parameters, Q‐factor and inductance values as well as in self‐resonance frequency values within 8% tolerance with measurement and full‐wave electromagnetic field solver. [ABSTRACT FROM AUTHOR]

A miniaturised rat‐race coupler capable of suppressing the second and third harmonics is proposed. The coupler is designed with slow‐wave synthesised transmission lines using two π‐networks in cascade. Each π‐network is formed by a parallel LC tank and two shunt capacitors, and is associated with a transmission zero for harmonic attenuation. The two transmission zeros embedded in the synthesised line can be controlled independently. The proposed rat‐race coupler, centred at 2.4 GHz with an operational bandwidth of 18.8%, and at least 21‐dB suppression at the second and third harmonics, features a compact footprint, which is only 12.9% the size of its conventional counterpart. [ABSTRACT FROM AUTHOR]