Abstract Transmission expansion planning (TEP) is a vital process of ensuring power systems' reliable and efficient operation. The optimization of TEP is a complex challenge, necessitating the ...application of mathematical programming techniques and meta-heuristics. However, selecting the right optimization algorithm is crucial, as each algorithm has its strengths and limitations. Therefore, testing new optimization algorithms is essential to enhance the toolbox of methods. This paper presents a comprehensive study on the application of ten recent meta-heuristic algorithms for solving the TEP problem across three distinct power networks varying in scale. The ten meta-heuristic algorithms considered in this study include Sinh Cosh Optimizer, Walrus Optimizer, Snow Geese Algorithm, Triangulation Topology Aggregation Optimizer, Electric Eel Foraging Optimization, Kepler Optimization Algorithm (KOA), Dung Beetle Optimizer, Sea-Horse Optimizer, Special Relativity Search, and White Shark Optimizer (WSO). Three TEP models incorporating fault current limiters and thyristor-controlled series compensation devices are utilized to evaluate the performance of the meta-heuristic algorithms, each representing a different scale and complexity level. Factors such as convergence speed, solution quality, and scalability are considered in evaluating the algorithms’ performance. The results demonstrated that KOA achieved the best performance across all tested systems in terms of solution quality. KOA’s average value was 6.8% lower than the second-best algorithm in some case studies. Additionally, the results indicated that WSO required approximately 2–3 times less time than the other algorithms. However, despite WSO’s rapid convergence, its average solution value was comparatively higher than that of some other algorithms. In TEP, prioritizing solution quality is paramount over algorithm speed.
Purpose. There is a trend of transition from a purely centralized power supply to a combined one, the number of local decentralized sources of electricity directly in the distribution networks is ...increasing. Distribution electric networks are transformed into a network with features characteristic of a local electric system, which receives power both from its own distribution electric networks and from a centralized source. Renewable energy has a number of advantages, but there are also disadvantages. Among them - the complication of the operation of electric networks with the growth of the capacities of renewable sources of electricity installed in them and the instability of generation due to their natural dependence on meteorological conditions, if we talk about technical shortcomings, then this refers to the sinusoidal nature of voltages and currents and voltage deviations, ensuring the quality of electricity which directly depends on ensuring the balance of active and reactive power in the electrical system. The purpose of this article is to analyze the effectiveness of reactive power compensation devices as a tool for reducing the threshold of integration of distributed generation sources into the electrical networks of Ukraine. The task is to study the reduction of the integration threshold for distributed generation. Research methods. Mathematical modeling of an electrical system with distributed generation elements and reactive power compensation devices. The influence of the operation of reactive power compensation devices on the parameters of the electric network is studied. Comparative analysis of network parameters and their change when implementing distributed generation together with and without reactive power compensation devices. The results obtained. The obtained results show that the use of reactive power compensation devices makes it possible to increase the carrying capacity of operating power lines and transformers, which is especially important when most of the power system schemes where distributed generation is integrated are of radial type, i.e. it actually lowers the integration threshold for renewable generation in the electric network. A very important factor is that the introduction of reactive power compensation devices together with distributed generation solves the problem of stabilization and voltage loss in electric networks, and also improves the quality of electric energy. Scientific novelty. The method of selecting reactive power compensators for distribution networks has been further developed, which differs from the existing ones by taking into account the presence of renewable energy sources of various types, which allows to increase the efficiency of the interaction of the local electric network with the renewable generation integrated in it. Practical value. It consists in lowering the integration threshold of distributed generation sources into electric networks by introducing reactive power compensation devices together with them, which affects a number of technological parameters in the node - reduction of power and voltage losses, stabilization and control of voltage, improvement of electric power quality indicators.
We demonstrate an apodization technique by tapering the corrugations of spiral Bragg grating waveguides on the silicon-on-insulator platform, for the fundamental transverse magnetic mode. The ...transmission and reflection responses of uniform and apodized spiral Bragg grating waveguides are experimentally compared to show higher sidelobe suppression ratios by the proposed apodization scheme. We also present an apodized, period-chirped spiral Bragg grating waveguide, and the group delay of the proposed device has been measured; the results show an efficient suppression in the ripples of the group delay response.
Decentralized electricity markets and greater integration of renewables demand expansion of the existing transmission infrastructure to accommodate inflected variabilities in power flows. However, ...such expansion is severely limited in many countries because of political and environmental issues. Furthermore, high renewables integration requires additional reactive power support, which forces the transmission system operators to utilize the existing grid creatively, for example, take advantage of new technologies, such as flexible alternating current transmission system (FACTS) devices. We formulate, analyze, and solve the challenging investment planning problem of installation in existing large-scale transmission grid multiple FACTS devices of two types (series capacitors and static var compensators). We account for details of the ac character of power flows, probabilistic modeling of multiple load scenarios, FACTS devices flexibility in terms of their adjustments within the capacity constraints, and long-term practical tradeoffs between capital versus operational expenditures. It is demonstrated that proper installation of the devices allows to do both-extend or improve the feasibility domain for the system and decrease long-term power generation cost (make cheaper generation available). Nonlinear, nonconvex, and multiple-scenario-aware optimization is resolved through an efficient heuristic algorithm consisting of a sequence of quadratic programmings solved by CPLEX combined with exact ac power flow resolution for each scenario for maintaining feasible operational states during iterations. Efficiency and scalability of the approach are illustrated on the IEEE 30-bus model and the 2736-bus Polish model from Matpower.
In this paper, a comprehensive review of recent researches carried out in the area of optimal reactive power dispatch (ORPD) is presented. The literature review consists of a classification of ORPD ...problem, along with a survey on the strengths and weaknesses of different models proposed previously. Also, a stochastic multi-objective ORPD (SMO-ORPD) model is studied under load and wind power generation uncertainties. A two-stage stochastic model is employed for dealing with the uncertainties. The considered objective functions are real power losses (PLs) and operation & maintenance (O&M) cost of wind farms (WFs). The proposed SMO-ORPD problem is solved by considering voltage stability index (i.e. Lmax index). Besides, ɛ-constraint technique and fuzzy satisfying approach are employed to pick up the best compromise solution. Two cases are considered as follows: (i) voltage stability relaxed SMO-ORPD, and (ii) voltage stability constrained (VSC) SMO-ORPD. In this study, reactive power compensation devices are modelled as discrete control variables. Hence, the proposed SMO-ORPD problem is modelled as a mixed-integer non-linear programming optimisation problem. The SMO-ORPD problem is implemented in GAMS environment, and it is examined on the IEEE 30 and 118-bus test systems. The numerical results substantiate that in the case of VSC-SMO-ORPD, active PLs are higher than the other case, whereas O&M cost of WFs is not different considerably.
A photonic-waveguide at real nano-scales based on the concept of hybridization of plasmonic and photonic modes is designed and fabricated. A high-index layer of silicon to control vertical and ...lateral confinement is introduced under the nano-confinement layer of thermally grown SiO 2 , which together with optimized waveguide-width provides low-loss guidance of hybrid-plasmonic-mode. A 11-nm thick SiO 2 on silicon provides us an optical-confinement at real nano-scales with an acceptably low loss of 7 dB/cm. Also, the proposed device exhibits ultra-low dispersion on introducing a grating in the silicon layer. In addition, the dispersion value "crosses zero-dispersion" many times over a broad range of wavelength.
We explore optimization methods for planning the placement, sizing and operations of flexible alternating current transmission system (FACTS) devices installed to relieve transmission grid ...congestion. We limit our selection of FACTS devices to series compensation (SC) devices that can be represented by modification of the inductance of transmission lines. Our master optimization problem minimizes the l1 norm of the inductance modification subject to the usual line thermal-limit constraints. We develop heuristics that reduce this non-convex optimization to a succession of linear programs (LP) that are accelerated further using cutting plane methods. The algorithm solves an instance of the MatPower Polish Grid model (3299 lines and 2746 nodes) in 40 seconds per iteration on a standard laptop-a speed that allows the sizing and placement of a family of SC devices to correct a large set of anticipated congestions. We observe that our algorithm finds feasible solutions that are always sparse, i.e., SC devices are placed on only a few lines. In a companion manuscript, we demonstrate our approach on realistically sized networks that suffer congestion from a range of causes, including generator retirement. In this manuscript, we focus on the development of our approach, investigate its structure on a small test system subject to congestion from uniform load growth, and demonstrate computational efficiency on a realistically sized network.
In this work, a lateral 4H-SiC n-LDMOS transistor, based on the principle of a reduced surface field due to charge compensation, is investigated by numerical simulations, in order to find adequate ...fabrication parameters for a lightly doped p-type epitaxy in combination with a higher doped channel region. The purpose of this work is the integration into an existing technology for a 10 V 4H-SiC-CMOS process. The simulations predict in a blocking voltage of 1.3 kV in combination with an On-resistance of 17 mΩcm2 for a device with a RESURF structure with a total implanted Al concentration of 6∙1016 cm-3 and a depth of 1 μm, a field plate of 5 μm and a drift region of 20 μm. The threshold voltage varies from 5 V to 10 V, depending on the thickness of the gate oxide (50 nm to 100 nm).
This study introduces a techno-economic planning strategy of reactive power (VAr) in power transmission systems. This planning strategy primarily has been focused on reactive power planning (RPP) ...through operating cost minimisation ensuring cost-oriented system security. The objective function (operating cost) is blended with four different components viz. cost due to real power loss, VAr generation cost, additional VAr compensation devices cost and line charging cost. FACTS (flexible AC transmission system) devices are installed at weak positions through different echelons to improve the system voltage stability. The authors also implemented the probabilistic hybridisation of crow search algorithm and JAYA to find out the optimal set of controlling parameters related to VAr. Finally, a sharp and minute analysis of the results has been done to validate the proposed strategy under multi-loading conditions. To understand the efficiency and efficacy the code profiling and simulation has been rendered on IEEE 30 bus and UPSEB 75 bus test system.
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